chapter 23: respiratory system Flashcards
the respiratory system
used to acquire oxygen and remove carbon dioxide from the blood
anatomy of the respiratory system
seven structures: external nose, nasal cavity, pharynx, larynx, trachea, bronchi, lungs
external nose
air inspiration
nasal cavity
cleans, warms, and humidifies air (air passageway); contains olfactory epithelium for sense of smell; resonating chambers for speech with paranasal sinuses
how does the nasal cavity clean air?
with hairs in the vestibule and cilia in the nasal conchae
conchae
create turbulence and increase surface area
how does the nasal cavity warm and humidify air?
with pseudostratified ciliated columnar epithelium that have goblet cells and tears the drain from the nasolacrimal duct
paranasal sinuses
formed by the frontal, sphenoid, ethmoid and maxillary bones; lighten the skull
help warm and moisten air moving through the upper respiratory tract
sinusitis
inflammation (of paranasal sinuses) that can lead to a headache
pharynx
common passageway for food and air; common opening for digestive and respiratory systems
three regions of the pharynx
nasopharynx, oropharynx, laryngopharynx
nasopharynx
pseudostratified columnar epithelium with goblet cells; openings of eustachian (auditory) tubes; floor is soft palate and uvula
mucus and debris swallowed; posterior wall houses pharyngeal tonsils
oropharynx
lined with moist stratified squamous epithelium
shared with the digestive system; contains palatine and lingual tonsils
laryngopharynx
lined with moist stratified squamous epithelium
epiglottis to esophagus
larynx
voice box that houses ligaments used for speech; keeps airway patent
ligaments extend from arytenoids to thyroid cartilage
functions of the larynx
maintain an open passageway for air movement (thyroid and cricoid cartilages)
epiglottis and vestibular folds prevents swallowed material from moving into the larynx
vocal folds are the primary source of sound production
pseudostratified ciliated columnar epithelium traps and prevents debris from entering the lower respiratory tract
cartilages of the larynx
thyroid, cricoid, epiglottis, arytenoid, corniculate, cuneiform
thyroid cartilage
largest; adam’s apple (laryngeal prominence)
cricoid cartilage
most inferior; base of the larynx
epiglottis
attached to the thyroid cartilage; has a flap near the base of the tongue (elastic)
arytenoid cartilage
attached to the cricoid cartilage
corniculate cartilage
attached to the arytenoid cartilage
cuneiform cartilage
contained in a mucous membrane anterior to the corniculate cartilage
vestibular folds
false vocal cords
vocal folds
true vocal cords; produce sound
glottis
opening between vocal folds
trachea
air cleaning tube that goes into the lungs (membranous tube of dense regular connective tissue and smooth muscle)
supported by 15 to 20 hyaline cartilage c-shaped rings
trachealis muscle
posterior surface of trachea that contracts when coughing
note: esophagus is posterior
epithelium of trachea
lumen is lined with pseudostratified ciliated columnar epithelium that contain goblet cells
note: goblet cells secrete mucus that traps debris, while cilia push it toward the larynx and pharynx
the trachea divides to form left and right _____ (bronchus)
primary bronchi
carina
cartilage at bifurcation that initiates a cough reflex when irritated with debris
bronchi and bronchioles
tubes that direct air into the lungs
tracheobronchial tree
the trachea and a network of air tubes in the lungs that are ciliated for removal of debris
cartilage holds tubes open and smooth muscle controls diameter
as tubes (bronchi) become smaller the amount of cartilage _____ and the amount of smooth muscle _____
decreases; increases
passage of bronchi from largest to smallest
primary bronchi, secondary (lobar) bronchioles, tertiary (segmental) bronchioles, bronchioles, terminal bronchioles
secondary (lobar) bronchioles
each serve a lobe of the lungs; contain cartilage plates lined with pseudostratified ciliated columnar epithelium
tertiary (segmental) bronchioles
supply bronchopulmonary segments
bronchioles
less than one millimeter in diameter
terminal bronchioles
have no cartilage; prominent smooth muscle lined with ciliated simple cuboidal epithelium
bronchodilation
smooth muscle relaxes causing a decrease in resistance to airflow, which leads to an increase in airflow
bronchoconstriction
smooth muscle contracts causing an increase in resistance to airflow, which leads to a decrease in airflow
example: asthma attack
asthma attack
severe bronchoconstriction due to inflammation
alveoli
site of pulmonary gas exchange; respiratory bronchioles branch from terminal bronchioles and have very few alveoli
300 million alveoli between two lungs
alveoli have no cilia so how is debris removed within this structure?
by macrophages that move into nearby lymphatics or into terminal bronchioles
alveolar ducts
alveoli open from ducts from respiratory bronchioles
alveolar sacs
chambers connected to two or more alveoli at the end of an alveolar duct
type I pneumocytes (alveolar wall)
thin squamous epithelial cells; 90% of surface of alveolus
function in gas exchange
type II pneumocytes (alveolar wall)
round or cube-shaped secretory cells
function in producing surfactant that allows alveoli to expand during inspiration
what is the location of pulmonary gas exchange
the respiratory membrane
respiratory membrane
membrane that is very thin and composed of an alveolar cell layer, capillary endothelial layer and interstitial space (air-blood barrier)
layers of the respiratory membrane
1) thin layer of fluid that lines alveolus, 2) alveolar epithelium (simple squamous), 3) basement membrane of alveolar epithelium, 4) thin interstitial space, 5) basement membrane of capillary endothelium, and 6) capillary endothelium (simple squamous epithelium) - lumen (blood)
pleura
thin double-layered serosal membrane that divides the thoracic cavity into pleural compartments and mediastinum
pleural cavity
surrounds each lung; is formed by pleural membranes from the thoracic cavity
filled with pleural fluid
pleural fluid
lubricated and assists in expansion and recoil of the lungs (friction decreases)
visceral pleura
adheres to the lungs
simple squamous epithelium
parietal pleura
adheres to the internal thoracic wall, superior diaphragm, and heart
pleurisy
inflammation of the pleura (often from pneumonia)
lungs
network of alveoli and capillaries for gas exchange
three lobes on the right; two lobes on the left
base (of lungs)
sits on the diaphragm
apex (of lungs)
above the clavicle (superior portion)
hilum (of lungs)
where bronchi and blood vessels enter (medial surface)
right lung
three lobes separated by fissures
left lung
two lobes and the cardiac notch
pulmonary arteries
bring poorly oxygenated blood to the lungs from the right side of the heart for oxygenation
pulmonary veins
return oxygenated blood to the left side of the heart
superficial and deep lymphatic vessels exit from the _____
hilum
divisions of the respiratory tract
conducting zone and respiratory zone
conducting zone
everything from the nose to the small air tubes in the lungs; strictly for pulmonary ventilation
respiratory zone
specialized, small tubes and alveoli; where gas exchange occurs
primary functions of the respiratory system
pulmonary ventilation, external respiration, transport of respiratory gases, internal respiration
pulmonary ventilation
breathing
external respiration
gas exchange between blood and lungs (specifically alveoli)
transport of respiratory gases
blood carries gases throughout the body
internal respiration
gas exchange between blood and tissue cells (cellular respiration)
additional functions of the respiratory system
1) regulation of blood pH (altered by changing blood carbon dioxide levels)
2) production of chemical mediators (ACE involved in blood pressure regulation)
3) voice production (movement of air past vocal folds makes sound and speech)
4) olfaction (smell occurs when airborne molecules drawn into nasal cavity
5) protection (preventing entry of microorganisms and removing them from the respiratory surfaces
boyle’s law
as volume of a container increases (thoracic cavity during inspiration), pressure inside said container decreases
gas pressure (P) = constant at a given temperature (K) / volume (V)
note: pressure and volume are inversely proportional
true or false: air flows down its pressure gradient
true
inspiration
air flows into the lungs
expiration
air flows out of the lungs
air flow in tubes is due to the _____ between areas
change in pressure
F =delta(P) / R
atmospheric pressure (P atm)
760 mmHg at sea level = nitrogen + oxygen + carbon dioxide + water vapor
respiratory pressures relative to atmospheric pressure
1) negative respiratory pressure is less than atmospheric pressures, 2) positive respiratory pressure is greater than atmospheric pressure, and 3) zero respiratory pressure is equal to atmospheric pressure
intrapulmonary pressure (P pul)
pressure in alveoli (P alv); fluctuates with breathing and always eventually equalizes with atmospheric pressure
what forces promote the lung to collapse?
elasticity of lungs and surface tension of the alveolar surfactant
what forces promote lung expansion?
elasticity of the chest wall and low intrapleural pressure (meaning pressure in pleural space is lower than the pressure in the lungs)
pleural space
acts like a vacuum by sucking the lungs open
pneumothorax
atelectasis; a collapsed lung due to the removal of a change in pressure
partial pressure
pressure exerted by each gas in a mixture
partial pressure of a gas = % of gas x the total pressure
dalton’s law
total pressure = the sum of the individual pressure of each gas
solubility coefficient
measure of how soluble a gas is in a liquid
henry’s law
concentration of a gas in a liquid is determined by its partial pressure and its solubility coefficient at a given temperature
concentrate of dissolved gas = pressure of gas x solubility coefficient
diffusion coefficient
rate at which gas diffuses into and out of a liquid or tissue
factors contributing to diffusion coefficient
solubility coefficient and molecular weight of a gas
diffusion of gases through the respiratory membrane depends on what?
membrane thickness, diffusion coefficient, surface area, and partial pressure differences
how does membrane thickness affect the diffusion of gases through the respiratory membrane?
increased thickness = decreased diffusion rate
mechanisms of alveolar pulmonary ventilation
atmospheric air pressure and intrapulmonary pressure
mechanisms of alveolar pulmonary ventilation at rest
1) intrapulmonary pressure = atmospheric pressure, meaning there is no air movement at the end of expiration
2) intrapulmonary pressure is less than atmospheric pressure (increase in thoracic volume), meaning air is moved into the lungs
3) intrapulmonary pressure = atmospheric pressure, meaning there is no air movement at the ned of inspiration
4) intrapulmonary pressure is greater than atmospheric pressure (decrease in thoracic volume), meaning air is moved out of the lungs
what affects alveolar ventilation?
lung recoil, alveolar elastic recoil, surface tension
lung recoil
tendency for the lungs to decrease in size after being stretched
alveolar elastic recoil
alveolar walls return to their original shape after being stretched
surface tension
film of fluid lining alveoli tends to make the alveoli collapse due to water molecule polarity
surfactant
reduces surface tension; produced by type II pneumocytes
infant respiratory distress syndrome
inadequate surfactant in premature babies
diffusion through the respiratory membrane depends on what?
diffusion coefficient of gas, partial pressure gradients, membrane thickness, surface area
partial pressure gradients (diffusion through respiratory membrane)
alveolar pressure of oxygen is greater than blood pressure of oxygen (opposite is true for pressure of carbon dioxide)
membrane thickness (diffusion through respiratory membrane)
a thicker respiratory membrane = a lower diffusion rate
tuberculosis or pneumonia can increase membrane thickness
surface area (diffusion through respiratory membrane)
decrease in surface area = decrease in diffusion rate
emphysema or lung cancer decreases available surface area
external respiration and internal respiration is driven by _____
pressure gradients
ventilation
amount of gas reaching the alveoli
perfusion
amount of blood flow circulating by the alveoli
ventilation-perfusion coupling is tightly regulated by _____
external respiration
transport of oxygen
98.5% of oxygen transport is done by hemoglobin (Hb) and about 1.5% of oxygen is dissolved in plasma
note: hemoglobin has cooperative binding for oxygen
factors affecting hemoglobin’s affinity for oxygen
1) partial pressure of oxygen - more oxygen is released if partial pressure of oxygen decreases in the tissues
2) temperature - more oxygen is released when temperature increases
3) blood pH - more oxygen is released when pH decreases
4) partial pressure of carbon dioxide - more oxygen is released when partial pressure of carbon dioxide increases
5) 2,3-bisphosphoglycerate (BPG) - more oxygen is released when BPG increases
transport of carbon dioxide
about 7% of carbon dioxide is dissolved in plasma, about 23% of carbon dioxide is bound to the globin of hemoglobin, and about 70% of carbon dioxide is transported as bicarbonate ion (HCO3-)
haldane effect
as hemoglobin binds to carbon dioxide, its affinity for oxygen decreases
less oxygen bound to hemoglobin means carbon dioxide can _____ (and vice versa)
bind
bicarbonate ion transport of carbon dioxide
either in the cytoplasm of red blood cells or in blood plasma
CO2 + H2O <> H2CO3 (carbonic acid) <> H+ + HCO3- (catalyzed by carbonic anhydrase - CA)
what occurs when carbon dioxide levels are high in the tissues?
HCO3- and Cl- antiporter removes HCO3- from red blood cells via the chloride shift, promoting HCO3- formation in the red blood cells
transport of carbon dioxide in the lungs
1) HCO3- moves into the red blood cells and binds with H+ to produce H2CO3-
2) H2CO3 becomes CO2 + H2O
3) CO2 diffuses from the blood into the alveoli
venous reserve
arterial blood oxygen saturation is about 98%, capillaries receive about 25% of oxygen, and about 75% of venous blood is saturated
most oxygen still bound to hemoglobin (_____) for low partial pressure of oxygen in high altitudes or heavy exercises
venous reserve
local control of pulmonary ventilation
1) pulmonary capillary perfusion
2) pulmonary ventilation-perfusion coupling: is disrupted by insufficient blood flow or air flow to the alveoli
3) regional distribution of blood flow is partially determined by alveolar partial pressure of oxygen (primarily by gravity)
4) low partial pressure of oxygen results in arterioles constricting, so blood is shunted to the region of the lung where alveoli are better ventilated
5) in other body tissues, low partial pressure of oxygen results in arterioles dilating to deliver more blood to tissues
neural control of pulmonary ventilation
under voluntary control when eating or speaking
under involuntary control during sleep or when focused on other tasks
medullary respiratory center (respiratory areas in the brainstem)
ventral respiratory groups (VRG) and dorsal respiratory groups (DRG)
ventral respiratory groups (VRG)
produces normal involuntary rhythm of breathing (eupnea)
dorsal respiratory groups (DRG)
receives input from chemoreceptors, mechanoreceptors and other sources to modify respiratory rhythm; stimulates diaphragm (phrenic nerve)
pontine respiratory center (respiratory areas in the brainstem)
pontine (pneumotaxic) respiratory group (PRG)
pontine respiratory group (PRG)
modulates pulmonary ventilation rate
some neurons operate only in inspiration and others only in expiration (some in both)
connects to medullary respiratory center and appears to play a role in switching between inspiration and expiration
effects of partial pressure of carbon dioxide and pH on respiratory rate
carbon dioxide is a major regulator of pulmonary gas exchange during rest of exercise
a small increase in blood carbon dioxide concentration triggers a large increase in rate and depth of ventilation, also known as hyperventilation
_____ in blood pH triggers hyperventilation
decrease
hypercapnia
partial pressure of carbon dioxide is greater than normal
hypocapnia
partial pressure of carbon dioxide is less than normal
_____ chemoreceptors are more important for the regulation of partial pressure of carbon dioxide and pH
medulla oblongata
_____ respond rapidly to change in blood pH due to exercise
carotid bodies
hering-breuer reflex and respiratory rate
sensed by mechanoreceptors; limits depth of inspiration and prevents overinflation of lungs
how does the hering-breuer reflex limit depth of inspiration and prevent overinflation of lungs?
stretch receptors in the walls of the bronchi and bronchioles; action potentials are initiated with stretch and inhibit the respiratory center, resulting in expiration
cerebral and limbic system control of respiratory rate
rate and depth of respiration are controlled voluntarily and involuntarily by the cerebral cortex
during exercise, respiratory rate changes are controlled by inputs to the respiratory center
emotions affect respiratory center (example: hyperventilation or gasps when crying)
anaerobic threshold
highest level of exercise without significant change in blood pH
beyond this, pH decreases and pulmonary ventilation increases
apnea
absence of breathing (voluntary or involuntary)
tissues producing more ATP than at rest release more _____ which lowers _____
carbon dioxide; pH
increased activity raises _____ in tissues
temperature
right shift (shifting the oxygen-hemoglobin dissociation curve)
benefits the tissues: oxygen is needed to support an increase in ATP production
left shift (shifting the oxygen-hemoglobin dissociation curve)
benefits the lungs: hemoglobin attracts oxygen with stronger affinity so more oxygen enters the blood
effects of aging on the respiratory system
1) vital capacity, maximum pulmonary ventilation, maximum minute volume, and gas exchange decreases
2) residual volume and dead space increases
3) ability to remove mucus from respiratory passageways decreases
4) lung compliance increases due to lost alveoli
5) gas exchange across the respiratory membrane decreases
