Respiratory System Anatomy and Physiology

B) T2-T10

The breastbone is synonymous with sternum.

C) It articulates with the first rib.

The angle of Louis, otherwise known as the sternal angle, articulates with the second rib.

C) It is larger than the thoracic outlet.

The thoracic inlet is smaller than the thoracic outlet.

D) Trachea

The trachea, bronchi, bronchioles, and alveoli comprise the lower respiratory tract.

C) None of these

• The conducting zone consists of:
•    1. nose
•    2. pharynx
•    3. larynx
•    4. trachea
•    5. primary, secondary, and tertiary bronchi
•    6. terminal bronchioles

• The respiratory zone consists of:
•    1. respiratory bronchioles
•    2. alveolar ducts
•    3. alveolar sacs
•    4. alveoli

D) Alveolar ducts

The alveolar ducts, alveolar sacs, and alveoli are not lined with cilia.

B) Alveoli

A) Pharynx

The trachea, lobar bronchi, segmental bronchi, and subsegmental bronchi are classified as cartilaginous airways, whereas, the bronchioles and the terminal bronchioles are classified as noncartilaginous airways.

D) Only the first statement is true.

After this, there is an exchange of gases between the lungs and the blood, a process known as external respiration.

B) Only the first statement is true.

Muscular breathing movements and recoil of elastic tissues create the changes in pressure that result in ventilation.

C) Intraabdominal pressure

Intraalveolar pressure is also known as intrapulmonary presusre.

C) Inspiration

Expiration mainly occurs via relaxation of the diaphragm and passive recoil of the elastic tissues.

B) Early adulthood

D) Only the first statement is true.

Two small nasal bones and extensions of the maxillae form the bridge of the nose.

C) Parietal

Paranasal sinuses are air-filled cavities in the frontal, maxillary, ethmoid, and sphenoid bones.

B) All of these

C) Laryngopharynx

D) C6

C) Hyoid bone to the lower margin of the larynx

C) Laryngeal tonsils

Waldeyer's ring is a ring of lymphoid tissue that consists of adenoid (nasopharyngeal), tubal, palatine, and lingual tonsils.

D) It is formed by ten cartilages that are connected to each other by muscles and ligaments.

The larynx is formed by nine cartilages that are connected to each other by muscles and ligaments.

C) Both statements are true.

B) Trachea

Trachea is also known as windpipe.

C) Thyroid cartilage

A) Epiglottis

A) T5

C) Only the second statement is true.

The hyaline cartilage in the tracheal wall provides support and prevents the trachea from collapsing.

A) Only the first statement is true.

This type of mucosa is also seen in the nasal cavity and nasopharynx.

B) Both statements are true.

D) Only the second statement is true.

In the mediastinum, at the level of the fifth thoracic vertebra, the trachea divides into the right and left primary bronchi.

C) Only the first statement is true.

As the branching continues through the bronchial tree, the amount of hyaline cartilage in the walls decreases, whereas the amount of the smooth muscle increases.

D) Both statements are false.

The alveolar ducts and alveoli consist primarily of simple squamous epithelium, which permits rapid diffusion of oxygen and carbon dioxide.

C) Only the first statement is true.

The lungs are soft and spongy because they are mostly air spaces surrounded by the alveolar cells and elastic connective tissue.

B) Mediastinum

The two lungs are separated from each other by the mediastinum, which contains the heart.

B) Hilum

The only point of attachment for each lung is at the hilum, or root, on the medial side. This is also where the bronchi, blood vessels, lymphatics, and nerves enter the lungs.

B) Each lobe is supplied by one of the tertiary bronchi.

Each lobe is supplied by one of the secondary bronchi.

A) Has a cardiac notch on its medial side for the apex of the heart

The left lung is longer and narrower than the right lung. It has only two lobes.

C) Hilum

The visceral pleura is double-layered serous membrane that is firmly attached to the surface of the lungs. Meanwhile, the parietal pleura lines the wall of the thorax.

A) Both of these

D) Trachea

Airway generation	Structure
0	Trachea
1	Main bronchi
2	Lobar bronchi
3-4	Segmental bronchi
5-11	Subsegmental bronchi
12-15	Bronchioles
16	Terminal bronchioles
17-19	Respiratory bronchioles
20-22	Alveolar ducts
23	Alveolar sacs

D) 17th generation

D) Trachea

The first to seventh airway generations are responsible for the cough reflex.

D) Both statements are true.

D) Only the first statement is true.

The nasopharynx connects to the middle ear through the Eustachian tubes, which equalize the pressure between the ear and the nasal cavity.

A) Oropharynx

A) Adenoid tonsils

The adenoid tonsils are found in the nasopharynx.

B) Cricoid

The thyroid, cricoid, and epiglottis are unpaired cartilages.

D) Cricoid

D) Cricoid

A) Cricoid

The cricoid cartilage is prone to obstruction due to its circular shape.

B) Thyroid cartilage

C) Thyroid

The thyroid cartilage acquires its shield-like shape from the embryologic midline fusion of the two distinct quadrilateral laminae.

The laminae join at an angle of 120° in females and at 90° in males. The smaller thyroid angle explains the greater laryngeal prominence (“Adam's apple”), longer vocal cords, and lower-pitched voice in males.

C) Only the second statement is true.

The mucosa above the vocal cords is classified as nonkeratinized, stratified, squamous epithelium. This is to allow for smooth passage of food.

B) Pharynx

The mucus propelled towards the pharynx is either swallowed or expelled.

A) It consists of 18 to 20 C-shaped rings, which are made up of hyaline cartilage.

The trachea consists of 16 to 20 C-shaped rings, which are made up of hyaline cartilage.

D) Inferior border of cricoid cartilage

C) Thyroid

D) Thyroid

D) Both statements are true.

The lamina is much wider than the arch.

A) Only the first statement is true.

The epiglottis is attached to the internal surface of the thyroid cartilage and projects over the pharynx, allowing the passage of air into the larynx, trachea, and lungs.

B) Hyoid

C) Arytenoid

D) Corniculate

The corniculate cartilages are small, elastic, cone-shaped cartilages that articulate with the apices of the arytenoid cartilages.

D) Cuneiform

The cuneiform cartilages, also known as the Wrisberg cartilages, are two elongated fibrous pieces of yellow cartilage placed one on either side of the aryepiglottic fold.

A) The cricothyroid joint connects the inferior horn of the thyroid cartilage to the lamina of the cricoid cartilage.

The cricothyroid joint connects the inferior horn of the thyroid cartilage to the arch of the cricoid cartilage.

B) Cricothyroid joints

Rotational movements of the arytenoid cartilages at the cricoarytenoid joints can separate (abduct) the vocal folds, widening the rima glottidis or appose (adduct) the vocal folds, narrowing the rima glottidis.

B) Larynx

B) Both statements are true.

B) Its narrow anterior arch has a midline ridge that serves as a surface of attachment for the esophagus.

The cricoid cartilage has a narrow anterior arch (band portion) and a wider posterior lamina (signet portion) with a midline ridge that serves as a surface of attachment for the esophagus.

B) Only the second statement is true.

During swallowing, as the larynx moves upward and forward, the epiglottis swings downward to close off the laryngeal inlet.

C) Only the first statement is true.

The epiglottis is attached by its stalk to the inner aspect of the angle formed by the laminae of the thyroid cartilage via the thyroepiglottic ligament in the midline.

C) Both

B) Both statements are true.

C) Only the first statement is true.

This is possible because their larynx sits higher, and with further elevation during swallowing, the epiglottis slides up behind the soft palate, locking the larynx into the nasopharynx.

This anatomical arrangement which allows babies to feed and breathe at the same time is lost between 2 to 6 years of age, as the larynx gradually descends into the adult location.

D) Oropharynx

B) Laryngopharynx

C) Nasopharynx and oropharynx

A) Levator veli palatini

D) Palatine tonsil

A) Superior pharyngeal constrictor

A) Oropharynx

C) Superior and middle pharyngeal constrictors

D) Uvula

B) Auditory tube

B) Pharyngeal tonsil

C) Soft palate

A) Nasopharynx

A) Nasopharynx

C) Terminal bronchiole

B) Type I pneumocytes

D) Pulmonary artery

B) Endothelium and type I pneumocyte

C) Mast cells

B) Alveolar macrophages

A) Exocrine bronchiolar cells

C) Simple ciliated columnar epithelium

B) Type II pneumocytes

A) Bronchiole

B) Respiratory bronchiole

D) Ciliated pseudostratified columnar epithelium with Goblet cells

B) Ciliated cells

B) Lobar bronchi

C) Tracheal gland and Goblet cells

B) Elastic cartilage

A) Dense irregular connective tissue

D) Respiratory epithelium and lamina propria

C)  Ciliated cells and Goblet cells

D) Goblet cells

A) Dense connective tissue

D) Cartilage

D) Submucosa

C) Submucosa

C) Lamina propria and submucosa

A) Ciliated cells

C) Cilia

B) Cilia

B) Basement membrane

D) Elastic cartilage

C) Only the first statement is true.

Continual suction of excess pleural fluid into the lymphatic channels maintains slight suction between parietal and visceral pleurae.

B) Pain

Meanwhile, visceral pleura is sensitive to stretch.

A) Both statements are true.

A) Only the second statement is true.

All pulmonary volumes and capacities are usually about 20% to 25% less in women than in men.

B) 55 mmHg

The normal partial pressure of oxygen in the arterial blood ranges between 80 to 100 mmHg.

B) 88%

Normal oxygen saturation is 95% to 100%.

D) Dorsal respiratory group of neurons

The pneumotaxic and apneustic centers in the pons regulates the rate of respiration. The ventral respiratory group of neurons in the medulla controls voluntary expiration and acts to increase the force of inspiration.

B) Zone III

In zone I, the ventilation occurs in excess of perfusion. In zone II, the perfusion and ventilation are fairly equal.

D) Wheezes

Crackles or rales is discontinuous bubbling sound secondary to the presence of secretions. Rhonchi is a snoring sound secondary to mild narrowing of the airway.

C) Decreased or no breath sounds

Soft, rustling sound on inhalation are vesicular breath sounds which are normally heard in a healthy lung. Crackles are heard due to increased mucus production, whereas wheezes are heard because of airway narrowing. In pneumothorax, there is decreased or absent breath sounds because the presence of air in the pleural space increases the distance between the lungs and the thoracic wall, making the breath sounds difficult to hear.

A) None of these

C) Only the first statement is true.

Compliance is inversely related to the elastic recoil of the lungs, so thickening of the lung tissue will decrease lung compliance.

B) Decreases; increases

This scenario describes the Bohr effect. It describes hemoglobin's lower affinity to oxygen secondary to increases in partial pressure of carbon dioxide and/or decreased blood pH. This lower affinity, in turn, enhances the unloading of oxygen into the tissues to meet their oxygen demands.

C) The right main bronchus gives off the superior lobar bronchus after entering the hilum of the lung.

The right main bronchus gives off the superior lobar bronchus before entering the hilum of the lung, whereas the left main bronchus gives off the superior lobar bronchus after entering.

C) The cardiac notch lies in the lower lobe of the left lung.

The cardiac notch lies in the upper lobe of the left lung.

B) H+ activation of chemosensitive area of medulla

CO2 is the major controller of respiration as a result of direct effect of H+ on the chemosensitive area of medulla. H+ do not cross the blood-brain barrier; thus, the CO2 diffuses across the said barrier and is then converted into H+, which acts on the chemosensitive area of medulla. CO2 and H+ activation of carotid bodies are minimal under normal conditions.

B) Only the second statement is true.

The pneumotaxic center transmits signals to the dorsal respiratory group of neurons to "switch off" the inspiratory signals, thus controlling the duration of the filling phase of the lung cycle.

B) Ventral medulla

The basic rhythm of respiration is generated in the dorsal group of respiratory neurons, which is located almost entirely within the nucleus of tractus solitarius. When the respiratory drive for increased pulmonary ventilation becomes greater than normal, respiratory signals spill over into the ventral group, causing this group to also contribute to the respiratory drive. However, the ventral group of respiratory neurons remain almost totally inactive during normal quiet breathing.

C) Bronchi and bronchioles

The Hering-Breuer reflex mechanoreceptors are located in the bronchi and bronchioles and respond to increased stretch to limit respiration.

A) Right lung

Horizontal fissure is seen on right lung, whereas oblique fissure is seen on both lungs.

B) Both statements are false.

Bronchiectasis is a progressive form of obstructive lung disease characterized by irreversible destruction and dilation of airways generally associated with chronic bacterial infections. The most immediate symptom of this condition is persistent coughing with large amounts of purulent sputum, which is worse in the morning.

D) Only the first statement is true.

The symptoms develop suddenly, usually with a sharp, sticking chest pain that is worse on inspiration, coughing, and sneezing. The visceral pleura is insensitive to pain, so pain associated with pleurisy most likely comes from the inflammation of parietal pleura.

A) Only the first statement is true.

At the beginning of an attack, there is a sensation of chest constriction, inspiratory and expiratory wheezing, nonproductive coughing, prolonged expiration, tachycardia, and tachypnea.

B) Pancreas

Approximately 90% of patients with cystic fibrosis have pancreatic insufficiency with thick secretions blocking the pancreatic ducts, causing dilation of the small lobes of the pancreas, degeneration, and eventual progressive fibrosis throughout.

D) Rales

Wheezes are continuous breath sounds heard during exhalation and are comparable to a musical tone or a whistling sound. A pleural friction rub is a raspy breath sound caused by inflammation of the pleura.

B) Metabolic alkalosis

Metabolic and respiratory acidosis would result in decreased deep tendon reflexes. Respiratory alkalosis results in tachypnea.

A) Inspiration, closing of glottis, tightening of vocal cords, abdominal contraction, opening of glottis, expiration

A) Only the first statement is true.

Vibration is usually applied at the end of deep inspiration and is maintained throughout the end of expiration.

C) Vocal cords

The respiratory tract is divided into two sections at the level of the vocal cords; the upper and lower respiratory tract.

B) Only the first statement is true.

The lungs contain the respiratory bronchioles, alveolar ducts, alveolar sacs and alveoli.

D) It lies above the thyroid cartilage and vocal cords.

The upper respiratory tract lies above the cricoid cartilage and vocal cords.

D) Nasal conchae

The nasal conchae are bony projections found at the lateral walls of the nasal cavity.

D) Non-keratinized squamous epithelium

C) Laryngopharynx

Anteriorly, the laryngopharynx continues into the larynx, whereas posteriorly it continues as the esophagus.

D) Traches

A) Both statements are true.

D) Somatic plexus

Each hilum of the lung contains the following structures: principal bronchi, pulmonary artery, pulmonary veins, pulmonary autonomic plexus, bronchial vessels, and lymph nodes and vessels.

A) Club cells

Club cells, which are formerly known as Clara cells, are non-ciliated cuboidal cells that contribute to the production of surfactant.

A) Both statements are true.

D) Common cold

The common cold is a viral infection that usually involves the nose and the throat.

A) In the context of low PaO2, a raised PaCO2 suggests the patient has type 1 respiratory failure.

Type I respiratory failure (hypoxemic) involves low arterial oxygen pressure (PaO2) and normal or low arterial carbon dioxide pressure (PaCO2). Meanwhile, type II respiratory failure (hypercapnic) involves low PaO2 and high PaCO2.

	Normal Values
pH	7.35-7.45
PaO2	11-13 kPa or 82.5-97.5 mmHg
PCO2	4.7-6.0 kPa or 35.2-45 mmHg
HCO3-	22-26 mEq/L
Base excess	-2 to +2

D) Weak pulse

It should be bounding pulse.

C) Acute bronchitis

• The following are possible causes of type 2 respiratory failure
•    1. Increased airways resistance (e.g. emphysema, asthma)
•    2. Reduced breathing effort (e.g. opiate use, brain stem lesion, extreme obesity)
•    3. Decrease in the area of the lung available for gas exchange (e.g. chronic bronchitis)
•    4. Neuromuscular problems (e.g. Guillain-Barré syndrome, motor neuron disease)
•    5. Deformity (e.g. ankylosing spondylitis, flail chest)

B) Respiratory alkalosis

	Normal Values
pH	7.35-7.45
PaO2	11-13 kPa or 82.5-97.5 mmHg
PCO2	4.7-6.0 kPa or 35.2-45 mmHg
HCO3-	22-26 mEq/L
Base excess	-2 to +2

C) The bicarbonate is on the low end of normal, representing compensation to the acid-base imbalance.

The bicarbonate is on the low end of normal, but this does not represent compensation. Compensation would involve a much more significant reduction in HCO3–.

	Normal Values
pH	7.35-7.45
PaO2	11-13 kPa or 82.5-97.5 mmHg
PCO2	4.7-6.0 kPa or 35.2-45 mmHg
HCO3-	22-26 mEq/L
Base excess	-2 to +2

C) Insufficient mechanical ventilation

• The following are possible causes of respiratory alkalosis:
•    1. Anxiety (e.g. panic attack)
•    2. Pain (causes increased respiratory rate)
•    3. Hypoxia (often seen in ascent to altitude)
•    4. Pulmonary embolism
•    5. Pneumothorax
•    6. Iatrogenic (e.g. excessive mechanical ventilation)

D) As blood plasma becomes alkalotic, the concentration of biologically active component of blood calcium increases.

As blood plasma becomes more alkalotic, the concentration of freely ionized calcium, the biologically active component of blood calcium, decreases. This hypocalcemia is responsible for the paraesthesia often seen with hyperventilation.

D) The respiratory system can attempt to compensate for a metabolic alkalosis by increasing ventilation.

The respiratory system can attempt to compensate for a metabolic alkalosis by increasing PaCO2 or by decreasing ventilation. However, in the short term, the respiratory system will likely maintain PaCO2 within the normal range.

	Normal Values
pH	7.35-7.45
PaO2	11-13 kPa or 82.5-97.5 mmHg
PCO2	4.7-6.0 kPa or 35.2-45 mmHg
HCO3-	22-26 mEq/L
Base excess	-2 to +2

B) History of profuse vomiting


As a result of this patient’s profuse vomiting, he has lost significant amounts of HCL, a stomach acid. This results in a net loss of H+ ions, meaning less H+ to bind to HCO3– and therefore more free HCO3– in the system.

In addition, as a result of vomiting, the patient is volume depleted, which results in the release of aldosterone and other mineralocorticoids which in turn increase HCO3– reabsorption by the kidneys, further increasing the amount of free HCO3– in the serum.

	Normal Values
pH	7.35-7.45
PaO2	11-13 kPa or 82.5-97.5 mmHg
PCO2	4.7-6.0 kPa or 35.2-45 mmHg
HCO3-	22-26 mEq/L
Base excess	-2 to +2

A) An oxygen flow rate of 3L via nasal cannulae would be expected to deliver an inspired concentration (FiO2) of around 32%, therefore you would expect that the PaO2 would be approximately 20 kPa less than this.

• An oxygen flow rate of 3L via nasal cannulae would be expected to deliver an inspired concentration (FiO2) of around 32%, therefore you would expect that the PaO2 would be approximately 10 kPa less than this (e.g. 22 kPa). Therefore, 
• a PaO2 of 9.1 kPa is therefore grossly abnormal and indicates significant hypoxia.

	Normal Values
pH	7.35-7.45
PaO2	11-13 kPa or 82.5-97.5 mmHg
PCO2	4.7-6.0 kPa or 35.2-45 mmHg
HCO3-	22-26 mEq/L
Base excess	-2 to +2

A) If this derangement in CO2 was acute, there would have been time for a compensatory response from the metabolic system.

If this derangement in CO2 was acute, there would not have been time for a compensatory response from the metabolic system.

	Normal Values
pH	7.35-7.45
PaO2	11-13 kPa or 82.5-97.5 mmHg
PCO2	4.7-6.0 kPa or 35.2-45 mmHg
HCO3-	22-26 mEq/L
Base excess	-2 to +2

B) There is an evidence of respiratory compensation for the metabolic acidosis.

The PaCO2 is normal, so there is no evidence of respiratory compensation for the metabolic acidosis. A lower than normal PaCO2 suggest respiratory compression.

	Normal Values
pH	7.35-7.45
PaO2	11-13 kPa or 82.5-97.5 mmHg
PCO2	4.7-6.0 kPa or 35.2-45 mmHg
HCO3-	22-26 mEq/L
Base excess	-2 to +2

A) Urosepsis

Urosepsis is the most likely diagnosis given the clinical presentation and history of recent catheter change.

A) Anaerobic respiration produces uric acid as a byproduct, which has resulted in the addition of acid to the patient’s serum causing uremic acidosis.

Anaerobic respiration produces lactic acid as a byproduct, which has resulted in the addition of acid to the patient’s serum causing lactic acidosis.

C) There is no evidence of respiratory compensation.

There is an evidence of respiratory compensation as the value of PaCO2 is lower than normal.

	Normal Values
pH	7.35-7.45
PaO2	11-13 kPa or 82.5-97.5 mmHg
PCO2	4.7-6.0 kPa or 35.2-45 mmHg
HCO3-	22-26 mEq/L
Base excess	-2 to +2

A) The body attempts to compensate for the metabolic acidosis by hyperventilating to blow off CO2 and thereby decrease pH.

• The body attempts to compensate for the metabolic acidosis by hyperventilating to blow off CO2 and thereby increase pH. 
• This hyperventilation, in its extreme form, may be observed as Kussmaul respiration.

A) Base excess is lower than the normal range.

Base excess is within the normal range, indicating the absence of metabolic compensation.

	Normal Values
pH	7.35-7.45
PaO2	11-13 kPa or 82.5-97.5 mmHg
PCO2	4.7-6.0 kPa or 35.2-45 mmHg
HCO3-	22-26 mEq/L
Base excess	-2 to +2

B) Opiate 

The history suggests this man has taken an overdose of opioids given the reduced level of consciousness, respiratory depression and pinpoint pupils. The respiratory depression has led to hypoxia, hypercapnia, and ultimately respiratory acidosis.

	Normal Values
pH	7.35-7.45
PaO2	11-13 kPa or 82.5-97.5 mmHg
PCO2	4.7-6.0 kPa or 35.2-45 mmHg
HCO3-	22-26 mEq/L
Base excess	-2 to +2

A) The patient has respiratory alkalosis and type II respiratory failure.

The patient has respiratory alkalosis and type I respiratory failure, as evidenced by her low PaO2 and PaCO2.

	Normal Values
pH	7.35-7.45
PaO2	11-13 kPa or 82.5-97.5 mmHg
PCO2	4.7-6.0 kPa or 35.2-45 mmHg
HCO3-	22-26 mEq/L
Base excess	-2 to +2

B) Pulmonary embolus

From the clinical history, this patient may have a deep vein thrombosis and a secondary pulmonary embolus. This has resulted in an increased oxygen requirement.

The patient is likely hyperventilating to maintain her oxygenation level, but as a result is exhaling excessive amounts of CO2, leading to alkalosis.

	Normal Values
pH	7.35-7.45
PaO2	11-13 kPa or 82.5-97.5 mmHg
PCO2	4.7-6.0 kPa or 35.2-45 mmHg
HCO3-	22-26 mEq/L
Base excess	-2 to +2

C) Metabolic acidosis with respiratory compensation

A pH of 7.32 is low, suggesting acidosis. The HCO3- and the base excess are low, so the metabolic system most likely contributes to the acidosis. The PaCO2 is low, therefore the respiratory system is not contributing to the acidosis; however, a low PaCO2 indicates that the respiratory system is compensating for the acidosis.

	Normal Values
pH	7.35-7.45
PaO2	11-13 kPa or 82.5-97.5 mmHg
PCO2	4.7-6.0 kPa or 35.2-45 mmHg
HCO3-	22-26 mEq/L
Base excess	-2 to +2

B) This patient had a cardiac arrest which meant there was no period of impaired ventilation and end-organ perfusion.

• This patient had a cardiac arrest which meant there was a period of impaired ventilation and end-organ perfusion.
•  
• The hypercapnia caused respiratory acidosis, whereas the accumulation of products of anaerobic respiration (as a result of hypoxia and reduced end-organ perfusion) caused metabolic acidosis.

False

When swallowing, the soft palate would have to move upward in order to prevent food from entering the nose.

False

The elastic tissues within the vocal cords allow them to change their tension for vocalization.

False

The trachea contains rings of cartilage that surround the windpipe to keep it semirigid.

False

The tracheobronchial tree contains a ciliated mucous lining that helps remove foreign particles from them.

False

The respiratory membrane is comprised of an alveolar wall, a capillary wall, and their basement membranes.

B) Internal respiration

Internal respiration is also known as tissue respiration.

A) Serves as the site for initial gas exchange between blood and air

Gas exchange only occurs in the alveoli.

D) Cricoid

The cricoid cartilage is approximately at the level of C6.

C) Inferior to the false vocal cords

The false vocal folds are located at the inferior edge of the vestibule just above the true vocal folds. The space or gap between the two vocal cords is known as the rima glottidis.

C) Intralobular bronchioles

B) Alveolar sacs

B) Atmospheric pressure

D) Surfactant

C) Elastic recoil of thoracic muscles

B) Residual volume

C) Vital capacity

C) Dorsal respiratory group of the medullary rhythmicity center

D) Alveolar cell membrane, capillary membrane, and fused basement membranes

B) The partial pressure of oxygen in the lungs and in the blood

A) As oxyhemoglobin; as bicarbonate ions

C) Pharynx

Pharynx is also known as the throat.

B) Conchae

The nasal conchae or turbinates are long, narrow curled shelves of bone that protrude into the nasal cavity. The superior, middle and inferior conchae divide the nasal cavity into four groove-like air passages.

C) Nasopharynx

D) Mastoid

It should be maxillary.

C) Nasopharynx

The nasopharynx contains the pharyngeal (adenoid) tonsils, whereas the oropharynx contains the lingual and palatine (faucial) tonsils.

D) Oropharynx

D) Glottis

A) Bronchioles

A) Alveoli

D) Secretion of surfactant

B) Mediastinum

C) Low pH; high CO2

False

In the chloride shift, Cl- ions are exchanged for HCO3- in order to maintain a state of electrical balance (electrophysiologic homeostasis).

True

Oxygen is used in many metabolic steps to result in energy, including the citric acid cycle. Only a small amount of energy can be obtained anaerobically by human cells.

False

In swallowing, the epiglottis moves downward and the laryngeal muscles close the glottis to prevent food from entering the trachea.

False

The capillaries are found outside of the alveoli and do not come into direct contact with the air.

False

The diaphragm is comprised of skeletal muscle which is under voluntary and involuntary control mechanisms.

True

The surface tension between the pleura allow the lungs to fully expand while the surface tension within the alveoli could cause their collapse.

False

Respiratory distress syndrome, which is otherwise known as hyaline membrane disease, results from an inability to produce a surfactant from type II alveolar cells.

False

During inspiration, the diaphragm contracts and moves downward, causing the thorax to increase and the abdomen to decrease in size.

True

When the diaphragm contracts the pressure within the thoracic cavity falls because of the larger space, and is now below the atmospheric.

False

The compliance of the lung decreases as the lungs expand.

False

The anatomical dead space represents the amount of air that does not come in contact with the alveoli but remains in the passages.

True

The alveolar dead space is the amount of air that cannot functionally cross the alveoli for exchange because of changes such as poor capillary blood flow.

False

Bronchogenic carcinoma begins in the epithelial lining of the bronchial tree.

True

The alveolar ventilation rate is the breathing rate per minute times the tidal volume minus the physiologic dead space. In a male, this is around 4,200cc per minute in comparison to 6,000 cc per minute which is an average minute respiratory volume.

False

Oxygen is a vital gas required for cells but the body is least able to detect it directly, but instead relies on reflexes associated with pH or carbon dioxide. The direct response to low oxygen levels is weak.

False

Studies have now indicated that the stretch reflexes mediated by proprioceptors in the joints and muscles may have a greater effect on increasing heart rate than blood parameters.

False

Hyperventilation causes the excess elimination of carbon dioxide and H+ ions, therefore raising the pH. Alkalosis then causes CNS changes such as dizziness.

False

The respiratory membrane is the combination of the alveolar membrane and capillary membrane in contact with it.

True

The alveolar macrophages are able to move through the pores in the alveoli and are part of the reticuloendothelial system.

True

The movement of gases depends upon simple laws of diffusion; the capillary PCO2 is usually 45 mm Hg so there would be no net movement in this case.

True

The alveolar PO2 is 104 mm Hg while the pulmonary blood that leaves the lung, in the pulmonary veins, has a PO2 of 100 mm Hg.

False

Retrolental fibroplasia may develop and cause blindness in infants who have been exposed to excess oxygen or hyperoxia conditions, because of retinal capillary damage from the oxygen.

False

Atelectasis can occur in the infant respiratory distress syndrome. ARDS is the adult respiratory distress syndrome.

False

At high altitudes, the percent of oxygen may remain the same but there is a lower effective pressure because the atmospheric pressure and therefore the partial pressure is less than 160 mm Hg.

True

Hemoglobin releases its oxygen faster under conditions of acidity such as those generated during skeletal muscle contraction. The purpose is to increase muscle oxygen.

False

Carbon dioxide is transported on the NH2 of the globin as carbaminohemoglobin and oxygen is independently carried on the iron.

B) Cell respiration

During cell (tissue) respiration, oxygen enters the cell and carbon dioxide is eliminated. During this same exchange, intercellular metabolic reactions are also using oxygen to produce energy.

A) Pharynx

The lower respiratory tract includes the respiratory organs within the thorax and the upper respiratory tract includes those outside the thorax such as the nasal cavity.

B) Nasal pharynx

The external nares are the nostrils that open into the vestibule of the nasal cavity and the internal nares are the exit of the nasal cavity into the pharynx.

D) Cribriform plate

The olfactory nerves for smell pass through the foramina of the cribriform plate of the ethmoid bone on the superior nasal surface.

C) Pseudostratified epithelium

The entrance into the system is covered with stratified squamous epithelium which is followed by pseudostratified columnar epithelium.

C) Contains microvilli

Microvilli are cell extensions found in the gastrointestinal tract. Cilia move in a wavelike manner to remove foreign particles in the respiratory tract.

A) Zygomatic

The zygomatic bone is the solid cheek bone, whereas the frontal, ethmoid, sphenoid, and maxillary bones have mucus filled sinus cavities.

B) Pharynx

The pharynx is the throat which opens into the larynx or voicebox.

A) Oral pharynx

The palatine tonsils are within the fauces of the soft palate of the oral pharynx. The adenoids (pharyngeal tonsils) are in the nasal pharynx.

C) Larynx

The epiglottis is comprised of a mucous membrane-lined piece of cartilage that acts as a cover over the glottis of the larynx to prevent food from entering the trachea.

D) Arytenoid

The largest piece of cartilage is the thyroid.

D) Trachea

The trachea, which is also known as windpipe, contains C-shaped pieces of cartilage which allow the soft trachea to remain open.

C) Primary bronchi

The carina is an area of cartilage which separates the openings of the two primary bronchi.

D) 5

There are two secondary bronchi on the left and three on the right.

C) Lobules

The bronchioles enter the basic subdivision areas called the lobules. The respiratory bronchioles enter the alveoli.

B) Alveoli

The terminal sacs called the alveoli are the only areas specialized for capillary gas exchanges.

C) Bronchioles

The bronchioles have lost their cartilage and become mainly comprised of smooth muscle which causes them to collapse during the spasms of asthma.

C) Simple squamous

The respiratory bronchioles are lined with cuboidal cells which changes to simple squamous epithelium in the alveoli for diffusion.

C) 300,000,000

The average lung has around 300 million alveoli that represent a surface of about 70-80 square meters.

A) Simple diffusion

The main force that governs the movement of gases is the rate of diffusion which results from concentration differences.

A) Hilus

The hilus is the region that represents the door into the lung, whereas the apex is the narrowed superior surface.

B) Parietal pleura

The pleural cavity is the serous fluid-filled potential space between the two layers of the pleural membranes, namely the visceral and parietal pleurae.

B) Reduce friction

The pleural membranes are serous and slippery and allow the lungs to slide during breathing without damage from friction rubs.

A) 760

Atmospheric pressure at sea level is 760 mmHg or 1 atmosphere or 760 torr.

A) Ventilation

Ventilation is the movement of air throughout a duct system, while respiration is the exchange of gases. Breathing includes the mechanical events involved.

B) Phospholipids

Surfactant is a phospholipid. Surface tension, acting alone, would cause collapse.

D) Elastic recoil

Normal exhalation is said to be passive because muscles are not contracting. The elastic tissue in the lungs should be sufficient to compress the lungs.

D) 758

During inspiration, the thorax expands and the intra-pulmonary pressure falls below atmospheric. This negative pressure causes air to enter the lungs.

A) 760

A pneumothorax occurs whenever the pleural pressure reaches atmospheric, causing the lung to collapse. This may result from injury or disease.

C) Internal intercostal

The internal intercostal muscles between the ribs cause the cage to move downward and inward during forced exhalation.

C) Tidal volume

The tidal volume is around 500cc in an adult male and somewhat less in a female.

C) Residual volume

The residual volume is around 1,000cc and cannot be removed without collapsing the lungs.

D) Vital capacity

The vital capacity represents the deepest possible breath a person could take.

C) Physiologic dead space

The physiologic dead space is the sum of the anatomic and alveolar dead space volumes.

D) Emphysema

Emphysema involves loss of the elastic recoil capabilities of the lungs due to the replacement of normal alveolar tissue with fibrous scar tissue. Smoke is a major precipitating factor.

A) Bronchial asthma

Some persons develop an allergic reaction to foreign particles that results in severe episodes of bronchial smooth muscle spasms causing a restriction in airway flow.

D) Larynx

The distal parts of the lower respiratory tract lack the type of nerve supply that can act as a stimulus pathway to elicit a cough.

C) Hiccup

A hiccup is the sudden spastic contraction of the diaphragm and results in a sound of air striking the vocal cords. Reflexes such as these are associated with neurological and blood gas alterations.

D) Yawn

The yawn is a deep inhalation which is a reflex attempt to correct high carbon dioxide or low oxygen levels in the blood. The cause of hiccups is unknown.

B) Medulla oblongata

The medulla oblongata in the brain stem contains the rhythmicity areas that coordinate the incoming stimuli with outgoing responses (breathing).

B) Pneumotaxic area of pons

The most primary or vital centers for breathing are located within the medulla. The pons acts as an accessory center to modify the rate of medullary breathing impulses.

B) Increased carbon dioxide in the blood

The factors that stimulate breathing are high carbon dioxide, low pH, high acidity, and low oxygen levels in the blood.

A) Low oxygen in the blood

The brain does not normally respond to levels of oxygen directly but must rely on distal receptors in the aortic and carotid bodies. It is assumed that spinal fluid and blood pH levels should be closely similar.

C) Lung cancer

COPD is characterized by some impairment in the ability of the respiratory tree to deliver sufficient air to the sites of exchange. Lung cancer may or might not be obstructive.

A) Hering-Breuer reflex

There are stretch receptors in the pleural membranes and lungs that respond to excess inflation by causing reflex exhalation via the brain stain centers. One is the inflation or Hering-Breuer reflex.

B) Anxiety

Although an abnormal increase in breathing rate may be caused by a brain tumor or drugs, the most common cause is psychological in origin (anxiety).

C) Nitrogen

The air is 78% nitrogen, 21% oxygen, and 0.04% carbon dioxide. There is less than 0.05% argon and other gases present.

B) 160 mmHg

The partial pressure is the percent times total pressure or 21% times 760 mm Hg or 160 mm Hg. 0.3 mm Hg is the partial pressure of CO2.

A) 45 mmHg

The partial pressure of capillary carbon dioxide is 45 mm Hg which is greater than the 40 mm Hg in the alveolar air, allowing CO2 to leave the blood.

C) 104 mmHg

The PO2 of the alveolar air is 104mm Hg, while the capillary blood is 40 mm Hg, allowing oxygen to diffuse into the blood.

C) Arteries entering the lung

The pulmonary arteries carry the carbon dioxide rich blood from the tissues of the body to the site of exchange in the alveoli. Recall that CO2 is an end product of metabolism.

B) Pneumonia

Pneumonia is an inflammation of the lung alveoli that usually is caused by a bacterium such as Streptococcus. Tuberculosis is an infection that does not necessarily involve the alveoli.

D) Hemoglobin

Oxygen can only dissolve in water to a maximum of 3%. Most oxygen, 98%, is bound in the oxyhemoglobin of the erythrocytes.

A) Oxyhemoglobin

The ability of the heme of the hemoglobin to transport oxygen is based on physical laws of pressure and attraction. The plasma holds only 1.5 to 3% of the total oxygen.

C) Decreased pH

Hemoglobin will release its oxygen faster under conditions of increased acidity, higher temperatures, and carbon dioxide. It is most saturated when the blood is more alkaline.

C) CO

Carbon monoxide competes with oxygen causing carboxyhemoglobin to form. Nitrogen does not bind to hemoglobin.

B) As bicarbonate

Since CO2 readily reacts with water, bicarbonate ions are formed and represent the most common method of transporting carbon dioxide.

C) Carbonic anhydrase

Carbonic anhydrase is an enzyme found in erythrocytes that increases the chemical conversion of carbon dioxide into bicarbonate.

E) Squamous cells, make up 95% cell volume and allow gas exchange

Type I cells are thin and flat and form the structure of the alveoli. Type I alveolar cells are squamous (giving more surface area to each cell) and cover approximately 90–95% of the alveolar surface. Type I cells are involved in the process of gas exchange between the alveoli and blood. These cells are extremely thin (sometimes only 25 nm) – the electron microscope was needed to prove that all alveoli are covered with an epithelial lining. These cells need to be so thin to be readily permeable for enabling an easy gas exchange between the alveoli and the blood.

D) Being a male

Male sex is associated with a higher lung diffusing capacity, even after correcting for age and body size. On average, DLCO in males is about 10% greater than females.

A smaller body size results in decreased lung diffusing capacity. This is because smaller people have smaller lungs, with a lower alveolar surface area.

Older people have lower lung diffusing capacities. The diffusing capacity decreases by 2% per year after the age of 20.

The diffusing capacity is higher in a supine position. This is due to the increased volume of blood flowing through alveolar capillaries in the supine position, when compared to standing.

B) Increased arterial carbon dioxide tension

Increased arterial carbon dioxide tension stimulates respiration by activating central chemoreceptors. In fact, it is the only stimulus to which central chemoreceptors stimulate respiration in response, whereas peripheral chemoreceptors stimulate respiration in response to reduced arterial oxygen tension, increased arterial carbon dioxide tension and increased arterial hydrogen ion concentration.

However, in conditions where the arterial carbon dioxide tension is chronically increased, such as chronic obstructive pulmonary disease, the central chemoreceptors no longer stimulate respiration in response to increased carbon dioxide tension because they adapt to the new set point of increased arterial carbon dioxide tension. In this case, the person's respiratory drive solely depends on the peripheral chemoreceptors stimulating respiration in response to reduced arterial oxygen tension.

This explains why people with chronic obstructive pulmonary disease have a reduced percentage oxygen saturation compared to those without it and why this reduced saturation is maintained if they are given oxygen therapy. If this oxygen saturation was increased by oxygen therapy, it would remove the sole remaining stimulus to breathe (the reduced arterial oxygen tension to which the peripheral chemoreceptors respond) and lead to apnoea

B) Type 2 pneumocyte

Type 2 pneumocytes are small cuboidal cells found in alveoli that are able to reproduce and regenerate alveolar epithelium after injury. Type 2 pneumocytes also produce surfactant that lines the alveolus.

Type 1 pneumocytes are cells of the alveoli that facilitate gas diffusion. They are not capable to reproducing, but type 2 pneumocytes can differentiate into type 1 pneumocytes after injury.

Pseudostratified ciliated columnar epithelium and goblet cells together comprise the respiratory epithelium which lines the airways. These are not involved in the regeneration of alveolar epithelium post-injury

A) Type 2 pneumocyte

Type 2 pneumocystis secrete surfactant, which lowers surface tension.  Surface tension is, simply put, the propensity for H+ cations at the surface of a liquid to be drawn together - thus surface tension can be thought of as a collapsing force of airways. From week 25 (roughly), sufficient surfactant is secreted to decrease surface tension commensurate with viable respiration - babies born prior to this point require ventilatory support and corticosteroids.

Type 1 pneumocytes are extremely thin simple squamous epithelia lining the vast majority of the alveoli. They function to provide the media through which gaseous exchange occurs between airway and red blood cell.

Type 3 pneumocytes is an often used term to describe fixed macrophages that reside within the terminal airways, including alveoli, due to the constant risk of inhaling various pathogens.

Type 4 pneumocytes do not exist.

E) Bicarbonate ions

Carbon dioxide, produced by metabolizing tissues, diffuses out of cells and into blood plasma, where it is dissolved. Some of this carbon dioxide remains in the plasma however only a small proportion of the overall amount, therefore this is not the correct answer.

Most diffuses into red blood cells, where it is converted into bicarbonate ions by the enzyme carbonic anhydrase in the following reaction: CO2 + H2O <- -=""> HCO3- + H+. These bicarbonate ions are then transported to the lungs and reconverted back into carbon dioxide that is ready to be exhaled. Therefore this is the correct answer.

A small amount of carbon dioxide combines with hemoglobin to form carbaminohemoglobin and carboxyhemoglobin is a compound of carbon monoxide and hemoglobin. These are therefore not the correct answer.

A) J receptor

J receptors are sensory receptors that respond to chemical and mechanical stimuli. When the lung parenchyma is irritated, stimulation of J-receptors can reflexively induce tachypnea, mucus hypersecretion and bronchoconstriction.

Parasympathetic stimulation of bronchiolar smooth smooth muscle causes bronchoconstriction, while adrenergic stimulation results in bronchodilation due to relaxation of smooth muscle.

The main type of parasympathetic receptor in the lung is the muscarinic receptor (the nicotinic receptor is found at the neuromuscular junction of skeletal muscle).

Stimulation of the adrenergic B2 receptor causes bronchodilation and relaxation of the smooth muscles.

Slow adapting pulmonary stretch receptors sense changes in lung volume, and they do not directly affect changes in airway calibre.

C) The partial pressure of oxygen in alveoli is low compared to that in the external environment.

The partial pressure of oxygen in alveoli is low compared to that in the external environment. This is the case because carbon dioxide is simultaneously diluting the alveolar atmosphere and oxygen diffusion into capillaries is continuously occurring. 

The partial pressure of oxygen in alveoli is high compared to that in capillaries which allows an overall diffusion of oxygen into the blood down a concentration gradient. Oxygen then combines with haemoglobin, after crossing alveolar and capillary membranes, to form oxyhaemoglobin. It is in this form that enables oxygen to be transported around the body.

C) Cuboidal cells which secrete pulmonary surfactant

Type II cells secrete pulmonary surfactant to lower the surface tension of water and allows the membrane to separate, therefore increasing its capability to exchange gases. The surfactant is continuously released by exocytosis.

Type II alveolar cells cover a small fraction of the alveolar surface area. Type II cells are also capable of cellular division, giving rise to more type I and II alveolar cells when the lung tissue is damaged. These cells are granular and roughly cuboidal.

Type II alveolar cells are typically found at the blood-air barrier. They make up <5% of the alveolar surface.

A) Descending aorta

The lung has a dual blood supply, receiving deoxygenated blood from the right ventricle via the pulmonary artery and oxygenated blood via the bronchial circulation.

The pulmonary artery divides to accompany the bronchi.

The arterioles accompanying the respiratory bronchioles are thin-walled and contain little smooth muscle.

The bronchial circulation arises from the descending aorta.

These bronchial arteries supply tissues down to the level of the respiratory bronchiole.

The bronchial veins drain into the pulmonary vein, forming part of the normal physiological shunt.

D) Trachea

From the trachea to the periphery, the airways become smaller in size (although greater in number).

The cross-sectional area available for airflow increases as the total number of airways increases.

The flow of air is greatest in the trachea and slows progressively towards the periphery (as the velocity of airflow depends on the ratio of flow to the cross-sectional area).

In the terminal airways, gas flow occurs solely by diffusion.

D) 150 ml

The anatomical dead space refers to the air that resides in the conducting zone (from the nose or mouth down to the level of the terminal bronchioles) that does not participate in gas exchange. There is approximately 150ml in the anatomical dead space at any one time.

The significance of this dead space is that not all the air in each breath is available for the exchange of oxygen and carbon dioxide.

500ml is the approximate volume of air inspired at one time. Inspiration pushes the 150ml of "dead space" air from the conducting zone into the alveoli. In this way, 150ml of "old air" enter the alveoli along with 350ml of fresh inspired air and 150ml of the newly inspired air remains in the conducting zone.

D) Hypocalcemia

As blood plasma becomes more alkalotic, the concentration of freely ionised calcium, the biologically active component of blood calcium, decreases (hypocalcemia).

Because a portion of both hydrogen ions and calcium are bound to serum albumin, when blood becomes alkalotic, the bound hydrogen ions dissociate from albumin, freeing up the albumin to bind with more calcium and thereby decreasing the freely ionized portion of total serum calcium leading to hypocalcemia.

This hypocalcemia related to alkalosis is responsible for the paresthesia often seen with hyperventilation.

C) The volume in the lungs at maximal inflation.

The average total lung capacity of an adult human male is about 6 litres of air.

Tidal breathing is normal refers to normal breathing at rest. Tidal volume is the volume of air that is inhaled or exhaled in a single breath.

The average human respiratory rate is 30-60 breaths per minute at birth, decreasing to 12-20 breaths per minute in adults.

C) CSF [H+]

The central chemoreceptors of the central nervous system, located on the ventrolateral medullary surface, respond directly to CSF [H+]. They provide 80% of the respiratory drive.

CSF[H+] is derived via PaCO2 and is, therefore, an indirect response to PaCO2.

Circulating [H+] cannot cross the blood-brain barrier.

D) Simple cuboidal epithelium

Pseudostratified ciliated columnar epithelial cells predominate the mucous layer of the respiratory tract, and are termed "respiratory epithelia".

Stratified squamous epithelium lines the vocal ligaments (folds of mucosa lining the cricovocal ligament superiorly) due to constant abrasion, many thousands of times daily.

Goblet cells, secreting mucus, are present throughout the respiratory tract.

F) Primary Mycobacterium tuberculosis infection

The Ghon complex is the most frequent pathologic form of primary pulmonary tuberculosis. Mycobacterium tuberculosis first localizes in the lung parenchyma, then in the hilar lymph nodes. In both of these locations, a granulomatous reaction takes place. These lesions usually heal by fibrosis, leaving only small scars at the sites of remote tuberculous infection.

In some cases, owing to immunosuppression (e.g. AIDS, immunosuppressant treatment, and lymphomas), reactivation of dormant bacilli in old lesions or additional re-exposure leads to secondary tuberculosis, with the progression of lesions.

Sometimes, active lesions of the Ghon complex are discovered by chance at autopsy.

Disseminated infection is a sign of secondary tuberculosis due to lymphohematogenous dissemination and subsequent seeding of tubercle bacilli throughout the body, with myriad small granulomas forming in the lungs, spleen, liver, bone marrow, retina and adrenals.

Reactivation disease occurs when immunosuppression or immunocompromise results in the activation of bacilli in old lesions with progression to more severe disease. Cavitary disease and miliary tuberculosis may result.

Re-exposure disease may result in secondary tuberculosis and progression of lesions.

Scars due to remote healed tuberculosis are frequently found postmortem and listed in autopsy reports as incidental findings.

D) Vocal cord abduction

The posterior cricoarytenoid muscles are the sole abductors of the vocal cords in the larynx.

B) Sinuses

The pneumatic sinuses are the parts of the respiratory system that are normally sterile and free of pathogens.

A sinus is simply a cavity within the osseous skull that contains air. There a number of sinuses within the skull, including the maxillary, frontal and sphenoidal sinuses, as well as the mastoid and ethmoidal air cells. It is thought they reduce the density (and thus, mass) of the skull without compromising structural integrity. Another speculated reason for the development of sinuses is their secretions, described below, that distinctly separate the bone adjacent to the central nervous system from the outside, non-sterile environment of the naso-, oro- and laryngopharynx, and nasal cavity. Having a physical and immunological barrier has significant benefits if viewed in this light.

The sinuses contain mucous-secreting glandular epithelial cells. This mucous typically drains into the nasal cavity, and the retrograde movement of bacteria through these drainage foramen can lead to infection.

There are also B lymphocytes present here, which promote the secretion of IgA as a constituent of the mucous. It is this IgA that helps to prevent both bacterial infection and proliferation of bacteria if they do enter the sinuses. Infection in the sinuses is referred to as sinusitis, and this can be life-threatening if the surrounding bone becomes infected.

The other options - the laryngopharynx, alveoli, Eustachian tube and oral cavity - all contain bacteria or are more susceptible to pathogen invasion if there is disruption of the normal flora of that region. An infection of each of these can be a combined laryngitis and pharyngitis, pneumonia, acute otitis media due to bacterial invasion and migration into the Eustachian tube, and oral candidiasis.

D) Vocal cords

The arytenoid cartilages are attached to the superior aspect of the cricoid cartilage and to the inferior-posterior-medial aspect of the thyroid by the vocal cords. The arytenoid cartilages function as 'control levers' to either tense or relax the vocal cords to produce sound.

E) Ligament of Berry

The ligament of Berry is the structure connecting the thyroid gland to the thyroid and cricoid cartilages. Its other name is the suspensory ligament of the thyroid gland.

While conventionally described as being attached to both the thyroid and cricoid cartilages, it is usually only attached to the cricoid cartilage. In a minority of cases, it can extend up to the thyroid cartilage. The ligament of Berry is responsible for the superior and inferior displacement of the thyroid gland during swallowing.

The ligament of Treitz helps suspend the small intestine at the duodenojejunal flexure. It connects this portion of the small intestine to the connective tissue surrounding the superior mesenteric artery and the coeliac trunk.

The investing layer of the deep cervical fascia of the neck is a fascial layer that helps to separate the neck into different layers. It encloses the entire neck, and contains the trapezius and sternocleidomastoid muscles.

The triangle of Calot is a triangular space in the abdominal cavity formed by the inferior free edge of the liver, the common hepatic duct and the cystic duct. This space contains the cystic artery.

The internal spermatic fascia is found within the spermatic cord.

A) Cricothyroid muscle

The cricothyroid muscle receives motor innervation via the superior laryngeal nerve.

The recurrent laryngeal nerve supplies motor innervation to the vast majority of the internal muscles of the larynx (except the cricothyroid muscle).

C) Opening between the true vocal cords and the arytenoid cartilages

The rima glottidis can be defined as the opening between the true vocal cords and the arytenoid cartilages.

This space is closed by the lateral cricoarytenoid muscles and the arytenoid muscles and is opened by the posterior cricoarytenoid muscles.