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respiratory system
- made of all organs that move air in and out of the lungs
- grouped by structure and function
- structures: URT and LRT
- functions: conducting and gas exchange
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upper respiratory tract
nose and throat (pharynx)
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lower respiratory tract
larynx, trachea, bronchial tree, lungs
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conducting division
all tubes that move air in and out of lungs
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gas exchange division
- aka respiratory division
- terminal branch of duct system where O2 and CO2 move between air sacs and blood
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nose
- 2 divisions: internal and external
- 3 functions: modify sound for speech, smell via olfactory receptors, incoming air filtration, warming, moistening
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external nose
- nasal bone and hyline cartilage covered with skin
- lined with hair
- 2 external openings (nostrils)
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internal nose
- 2 nares: internal opening that contact throat
- 4 paranasal sinuses: cavities in bone that make it lighter
- openings for lacrimal ducts
- lateral walls: ethmoid, maxilla, inferior nasal concha
- floor: palatine bone
- septum: divides nose in 2
- posterior septum: vomer bone
- anterior septum: hyline cartilage
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pharynx
- funnel shaped passage
- begins at base of skull
- ends at C6
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nasopharynx
- above soft palate
- passageway for air
- pseudostratified ciliated columnar ET
- 2 openings into nose and 2 openings into Eustachian tube
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Eustachian tube
connects nasopharynx to middle ear
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oropharynx
- behind mouth between soft palate and hyoid
- stratified squamous non-keritinized ET
- passageway for food and air
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laryngopharynx
- between hyoid and larynx
- stratified squamous non-keritinized ET
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larynx
- voice box
- connects pharynx to trachea
- located at C6
- phonation: voice production
- helps keep airway open
- channels food and air into proper tubes
- 6 cartilages: thyroid cartilage, epiglottis, cricoid, arytenoid, corniculate, cuneiform
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thyroid cartilage
- Adam's apple
- front part of larynx
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epiglottis
flexible spoon like structure that covers trachea when food is swallowed
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cricoid
- ring of cartilage that forms inferior larynx
- landmark for trachs
- used to intubate
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arytenoid
paired cartilage that attaches to vocal cords to help them move
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corniculate
paired cartilage that attaches to arytenoid to indirectly move vocal cords
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cuneiform
help support vocal cords and epiglottis
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glottis
space inside larynx
-
vocal cords
- 2 string like structures that run through glottis
- speech is produced as air crosses cords
- tight cords: high sounds
- loose cords: low sounds
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trachea
- windpipe
- 4" long
- kept open by C-shaped rings of hyline cartilage
- lined with pseudostratified ciliated columnar ET w goblet cells
-
carina
inferior trachea before split into bronchial tree
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bronchial tree
- primary bronchus: one per lung
- secondary bronchus: one per lobe (3 R, 2L)
- tertiary bronchus: one per segment (10 per lung)
- all kept open by cartilage
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bronchioles
- hundreds
- first place in tree where cartilage disappears - could collapse
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respiratory bronchioles
- thousands
- tissue changes to simple squamous ET
- gas exchange first begins
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alveoli
- microscopic grape-like structures that form terminal branch of duct system
- simple squamous ET
- major site of gas exchange in the.body
- 3 types of cells: squamous pulmonary ET type 1, alveolar septal cells type 2, alveolar macrophages
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squamous pulmonary ET type 1
- largest cells
- form alveolar wall
- site of gas exchange
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alveolar septal cells type 2
produce surfactant
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alveolar macrophages
phagocytes that remove dust and bac from lungs
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surfactant
- gooey liquid that reduces surface tension in the lungs
- allows alveoli to expand
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left lung
- 2 lobes - superior and inferior
- separated by oblique fissure
- smaller than right
- contains cardiac notch (where heart rests against lung)
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right lung
- 3 lobes - superior, medial, inferior
- horizontal fissure: separates superior and medial lobes
- oblique fissure: separates medial and inferior lobes
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-
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mediastinum
mass of tissue between lungs
-
hilus
where bronchial tree enters lungs
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pressures
- 3 pressures control breathing
- atmospheric pressure
- intrapulmonic pressure
- intrapleural pressure
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atmospheric pressure
760 mmHg at sea level
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intrapulmonic pressure
- pressure inside the lungs
- not breathing:760
- inhale: 757
- exhale: 762
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intrapleural pressure
- pressure inside the pleural space
- must always be less than AP and intrapulmonic
- approximately 756
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atelectasis
any condition that equalizes pressures and causes collapsed lung
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pneumothorax
air in the pleural cavity
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Boyle's law
- explains how air moves in and out of lungs
- pressure of a gas in a closed container is inversely proportional to volume of container at constant temp
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inhalation
- active process involving skeletal muscle contraction
- body needs O2 - phrenic nerve contracts diaphragm down and intercostal nerves contract intercostal muscles up - thoracic cavity enlarges
- lungs expand - pressure drops - pressure gradient causes air to move in
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exhalation
- passive process involving elastic recoil of lung tissue
- as lungs recoil, slightly smaller than original size - intrapulmonic pressure greater than AP - air moves out down gradient
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compliance
- how easily the lungs and thoracic wall expand
- high compliance - easy
- low compliance - difficult
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airway resistance
friction encountered by air as it moves through tube system
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spirometer
device used to measure volumes and capacities
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tidal volume
- amt of air inhaled / exhaled during quiet breathing while resting
- 500 ml
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minute respiratory volume
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dead air volume
- amt of air that remains in tube system and does not participate in gas exchange
- 150 ml
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inspiratory reserve volume
- max amt of air that one can inhale after normal inspiration
- 3100 ml
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expiratory reserve volume
- max amt one can exhale after normal expiration
- 1200 ml
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residual volume
- amt that remains in lungs after ERV
- 1200 ml
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minimal volume
- amt in lungs after collapse
- variable
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vital capacity
- max amt exhaled after max inhale
- = TV + IRV + ERV
- 4800 ml
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inspiratory capacity
- total amt that can be exhaled
- = TV + IRV
- 3600 ml
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functional residual capacity
- amt of air that stays in the lungs after normal exhale
- = ERV + RV
- 2400 ml
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total lung capacity
= TV + IRV + ERV + RV
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gas exchange
- by simple diffusion
- explained by Dalton's Law
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Dalton's Law
- in a mix of gases, each individual gas exists independently
- each gas has its own pressure
- sum of all partial pressures = total pressure of mix
- pO2 = 160 in air (21%)
- p explains diffusion of O2, CO2 between alveoli/DOB and OB/tissues
- gases move from greater to lesser p
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external respiration
- diffusion of O2/CO2 across alveolar capillary membrane
- occurs between alveoli and pulmonary blood capillaries (DOB)
- converts DOB to OB
- inhale pO2 = 160
- alveolar pO2 = 104 / DOB pO2 = 40
- alveolar pCO2 = 40 / DOB pC02 = 45
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external respiration factors
- AC membrane microthin with huge surface area
- millions of pulm capillaries with extensive branches (lots of blood)
- p concentration gradient (easy diffusion)
- gases travel short distance
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TB
- alveolar walls thick and fibrous
- filled with bacteria
- trouble inhaling, exhaling, gas exchange
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emphysema
- alveolar walls erode
- 99% due to smoking
- trouble with exhaling, gas exchange
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internal respiration
- exchange of O2/CO2 between systemic blood capillaries and body tissues
- OB pO2 = 104 / tissue pO2 = 40
- OB pCO2 = 40 / tissue pCO2 = 45
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Henry's Law
- the ability of gas to dissolve in a solution depends on its p and its solubility coefficient
- explains O2/CO2 transport
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solubility coefficient
- determines how easily a gas dissolves
- high SC: dissolves quickly and easily
- low SC: dissolves slowly with difficulty
- O2/CO2 have low SC - do not dissolve well in plasma
- CO2 higher SC than O2
- O2: diffuse into RBC (attaches to heme)
- CO2: floats in plasma as HCO3- ions
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hyperbaria
pressure greater than 1 atm (760 mmHg)
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hyperbaric chamber
- contains O2 at a p greater than 160
- forces more than normal amount of O2 into blood
- used to treat CO poisoning, gangrene, tetanus (anerobic bac)
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scuba diving
- ex. of Henry's Law
- constantly breathing under hyperbaric conditions
- when descending, pressure of all gasses increases
- nitrogen is dangerous b/c SC is 0 - causes bubbles in the blood
- divers must surface slowly so bubbles can release in the lungs
- causes the bends, decompression sickness, nitrogen narcosis
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O2 transport
- 100ml OB contains 20ml O2
- 1.5% dissolves in plasma
- 98.5% diffuses into RBC (attaches to heme)
- forms H-bond with iron
-
alloesteric cooperativity
- O2 attaches one at a time
- each subsequent attachment is easier
-
fully saturated Hgb
- all Hgb bound to O2
- called oxyhemoglobin (HgbO2)
- occurs in lungs and OB
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partially saturated Hgb
- combination of HgbO2 and Hgb
- occurs in DOB and tissues
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deoxyhemoglobin
no Hgb bound to O2
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hemoglobin disassociation curve
- % saturation of O2
- all metabolically active tissues at rest need and use O2 and as a by-product of metabolism, produce CO2, heat, acid, BPG
- normal is homeostasis
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curve shifts right
- tissue more active, requires more O2
- more O2 released from Hgb
- increased CO2, temp, 2-3 BPG, acid
- Bohr effect
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curve shifts left
- tissue less active, requires less O2
- less O2 released from Hgb
- decreased CO2, temp, 2-3 BPG, acid
- Haldane effect
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BPG
produced as RBC breaks down glucose for energy
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CO2 transport
- major role in acid-base balance
- 100ml DOB contains 5ml C02
- carried in blood 3 ways
- 7% dissolves in plasma (diffuses easily in lungs)
- 23% enters RBC (carbaminohemoglobin)
- 70% carried in plasma as HCO3-
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carbaminohemoglobin
- HgbCO2
- CO2 attached to globin
- occurs in tissues and DOB
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chloride shift
- HCO3- enters RBC, immediately diffuses back into plasma
- at same time, Cl- ions move from plasma into RBC
- exchange of negative ions is critical to maintain electrical balance
-
carbonic anhydrase
enzyme that controls initial formation of HCO3- ions
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nervous control of resp
controlled by MO and pons
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medullary rhythmicity area
- in MO
- controls rhythm of breathing
- contains origin of phrenic and intercostal nerves
- 2 sec inhalation, 3 sec exhalation
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pneumotaxic
- in upper pons
- stops inhalation to prevent lung overinflation
- coordinates smooth transition between inhale/exhale
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apneustic
- in lower pons
- coordinates smooth transition between inhale/exhale
- allows for breath holding
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hering-brewer reflex
large group of stretch receptors that prevent lung overinflation
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apnea
temporary stop in breathing
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dyspnea
difficult and painful breathing
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hyperpnea
rapid breathing
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hypoxia
O2 levels in tissues reduced due to clogged blood vessels or breathing issues
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anoxia
no O2 to tissues due to breathing issues or completely clogged vessels
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respiratory acidosis
- blood pH < 7.35 b/c of hypoventilation
- slow, shallow breathing
-
respiratory alkalosis
- blood pH > 7.45 b/c of hyperventilation
- rapid breathing
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