Lecture Respiratory System Part 1

1. Pulmonary Ventilation (breathing): movement of air in and out of the lungs

2. External Respiration: O₂ and CO₂ exchange between the lungs and blood.

3. Transport: of O₂ and CO₂ using the blood

4.  Internal Respiration: O₂ and CO₂ exchange between the tissues and the blood.

Site of gas exchange

Respiratory bronchioles, alveolar ducts, and alveoli

Conduits of air

• Nose, nasal cavity, and paranasal sinuses
• Pharynx
• Larynx
• Trachea
• Bronchi and their branches

• 1. provides and airway for respiration
• 2. moistens and warms the entering air
• 3. filters and cleans inspired air
• 4.  Serves as a resoning chamber for speech
• 5. Houses olafactory receptors

• 
• 

Vibrissae

Pseudostratified ciliate columnar with goblet cells

Mucous and serous secretions contain lysozyme and defensins as a natural antibiotic

Cilia move contaminated mucus posteriorly to throact

Inspired air is warmed by plexuses of capillaries and veins

sensory nerve endings trigger sneezing

during inhilation: filter, heat, and moisten air

during exhalation: reclaim heat and moisture

Air passage posterior to nasal cavity

lined with pseudostratified columnar epithelium

soft palate and uvula close the nasopharynx during swallowing

Pharyngeal tonsils (Adenoids when swollen) on posterior wall

Pharyngotympanic (auditoty) tubes open in lateral walls with tubal tonsils

passage for food and air

lined with stratified squamous epithelium

isthmus of tha fauces: opening to the oral cavity

palantine tonsils on the lateral walls of fauces

Lingual tonsils at base of tongue

passage for both air and food

extends to the larynx where it is continuous with esophogus

• 8 hyaline cartilages:
• thyroid, cricoid, paired artynoid, paired cuniform, paired corniculate

• 1 elastic cartilage:
• epiglottis

• tracheal cartilage is also hyaline
• 

• Vestibular folds are superior and are called false vocal cords
• -no part in sound production
• -help close glottis during swallowing

Vocal folds are true vocal cords that vibrate to produce sound

the vocal ligaments are attached to the thyroid cartilage by the arytnoid cartilages and contain elastic fibers

Speech: intermittent release of expired air while opening and closing the glottis

Pitch: determined by the length and tension of vocal cords

Loudness: force of air

chambers of the pharynnx, oral, nasal, and sinus cavities amplify and resonate sound

sound is shaped into language by muscles of the pharynx, tongue, soft palate, and lips

Prevents air passage

• Example: Valsalva's Maneuver
• -glottis closes to prevent exhalation
• -abdominal muscles contract
• -intra-abdominal pressure rises
• -helps to empty the rectym or stabilize trunk during heavy lifting

1. Mucosa: ciliated pseudostratified epithelium with goblet cells

2. Submucosa: connective tissue with seromucous glands that secrete mucus sheets

3. Adventitia: outtermost layer composed of connective tisse that encloses the C shaped rings of hyaline cartilage

The branching of the Bronchi

23 orders of branching, beginning with the primary bronchi at the carina

Lobal (Secondary) bronchi into segmental (tertiary) bronchi

Cartilage rings give way to plates as they get loser to bronchioles

Bronchioles do not have cartilage, but have smooth muscle

Epithelium turns from pseudostratified columnar into cuboidal in bronchioles.  Goblet cells and cilia disappear

about 300 million alveoli

main site of gas exchange

The blood air barrier

alveolar and capillar walls and their basement membrane

Simple squamous epithelium (Type I cells)

Scattered Cuiboidal cells (Type II cells): secretre surfectant and antimicrobioal protetins

surrounded by fine elastic fibers

contain pores: connecting alveoli, allow pressure to be equalized, provide alternative air routes for collapsed or damaged tissue

house alveolar macrophages that keep surfaces sterile

• Right: 3 lobes separated by oblique and horizontal fissure. 10 bronchopulmonary segments
• Left: 2 lobes separated by oblique fissue-has cardiac notch. 8-9 bronchopulmonary segments

outside surface covered by hexagonal lobules that are served by bronchioles and their branches

• Pulmonary circulation: (low pressure, high volume)
• *remember it is opposite of the rest of the body
• -pulmonary arteries deliver systemic venous blood
• -lie anterior to main bronchi
• -pulmonary veins carry 0₂ blood back to heart

• Systemic Circulation (high pressure low volume)
• -bronchial arteries supply blood to lung tissue (run along branching bronchi)
• -arise from the aorta and enter lung at hilum
• -supply all lung tissue EXCEPT alveoli (they get it from the pulmonary circulation)

bronchial veins anastome with pulmonary veins

most venous blood is carried back to the heart by pumonary veins

-

Double layered serosa

Parietal pleura on thoracic wall and superior face of diaphram

visceral pleura on the external lung surface

pleural fluid fills slitlike pleaural cavity

provides lubrication and surface tension

Because of elastic recoil, the lungs always assume the smallest size possible.Surface tension on the alveoli also reduce its size (draws water molecules close together where it meets gas)

this promotes atelectasis! (collapse!)

• Surfectant (Secreted by Type II cells) Saves the day!
• -detergent like lipid protein complex
• -reduces surface tension and discourages alveolar collapse
• -insufficient quantity in premature infants causes infant respiratory distress syndrome (IRDS)

• 
• A meaure of the change in lung volume that occurs with a given change in  traqnspulmonary pressure

• Normally high due to:
• distensibility of lung tissue
• alveolar surface tesnion

*the higher the C_L the easier it is to expand the lungs

• Nonelastic scar tissue (fibrosis)
• reduced production of surfectant
• decreased flexibility in the thoracic cavity

• *homeostatic imbalances
• -deformities of the thorax
• -ossification of the costal cartilages (common in elderly)
• -paralysis of intercostal muscles

Chronic obstructive pulmonary disease

Exemplified by chronic bronchitis (chronic excessive mucus) and emphysema

irreversible decrease in the ability to force air out of the lungs (reduced FEV)

• 80% of patients have a history of smoking
• dyspnea: labored breathing
• coughing and frequent pulmonary infections
• most victims develop respiratory failure (hypoventiliation) accompanies by respiratory acidosis

Emphysema is a permanent enlargement of the alveolar and destruction of alveolar walls

Pink Puffer: works hard to maintain ventilation and is often red in the face

Blue Bloater: right side heart failure has reduced oxygen.  Air trapping frequently cuases bloated chest

characterized by coughing, dyspnea, wheezing, and chest tightness

active inflammation is an immune response caused by release of interleukins, productions of IgE, and recruitment of inflammatory cells

airways thickened with inflammatory exudate magnify the effect of bronchospasms

Infectious disease caused by teh bacterium mycobacterium tuberculosis

symptoms include fever, night sweats, weight loss, a racking cough, and spittig up blood

treatment entails a 12 month course of antibiotics

leading cause of cancer deaths in North America for both men and women

90% of all cases result of smoking

• 3 Most common types
• 1. Squamous cell carcinoma (20-40%) in bronchial epithelium
• 2. Adenocarcinoma (~40%) originates in the peripheal lung areas
• 3. Small cell carcinoma (~20%) contains lymphocyte-like cells that originate in the primary bronchi and subsequently metastasizes

Olfactory placodes invaginate into olfactory pits by 4th week

laryngotracheal buds are present by 5th week

mucosae of the bronchi and lung alveoli are present by the 8th week

by the 28th week, a premature baby can breathe on its own

during fetal life, the lungs are filled with fluid and blood bypasses the lungs

gas exchange takes place via the placenta

At birth, respiratory centers are activated, alveoli inflate, and lungs begin to function

respiratory rate is highest in newborns and slows until adulthood

lungs continue to mature and more alveoli are formed until young adulthood (any addtl alveoli are lost if start smoking young)

respiratory efficiency decreases in old age