chapter 22 Flashcards
functions of the respiratory system
gas exchange: body tissues must be supplied with O2 and CO2 must be disposed of
4 processes involved on gas exhange
- pulmonary ventilation: breathing
- external respiration: gas exchange occurring in the lungs
- transport of respiratory gases to/from tissues
- internal respiration: gas exchange occurring in the tissues
two zones of the respiratory system
- conducting zone
- respiratory zone
conducting zone
respiratory passages leading from the nose to the respiratory bronchioles
transports air to/from the lungs
no involvement in gas exchange
respiratory zone
actual site of gas exchange
found in respiratory bronchioles, alveolar ducts and alveoli
upper conducting zone
nasal cavity
pharynx
nasal cavity
air is warmed and humidified as it enters the nasal cavity: cold air slows down respiratory rate
mucous membranes of nasal cavity
respiratory mucosa has 2 cells
1. goblet cells: mucus-producing cells
2. seromucous nasal glands: mucous- traps particles and debris
serous- secretes watery fluid containing lysozymes (kills pathogens)
pharynx
divided into 3 regions
1. nasopharynx
2. oropharynx
3. laryngopharynx
nasopharynx
contains pharyngeal and tubal tonsils
closes during swallowing by soft palate and uvula
oropharynx
meets the oral cavity as isthmus of the fauces
contains palatine and lingual tonsils
laryngopharynx
respiratory and digestive passages split
lower conducting zone
splits laryngopharynx from respiratory passages
1. larynx
2 trachea
3. bronchi
epiglottis
cartilage flap that closes off lower conducting zone
when eating pushes over lower conducting zone to prevent food from entering
larynx (voice box)
composed of cartilage
- thyroid cartilage: Adams apple
- cricoid cartilage
keep larynx open
contains vocal cords for sound production
glottis
open passageway surrounded by vocal cords
vocal cords are
ligaments composed of elastic fibers
fibers vibrate as we exhale to produce sound
sound pitch vs sound loudness
chords are tense: higher pitch
air passed across chords w greater force: increase loudness
trachea (windpipe)
composed of elastic fibers and cartilage rings
- elastic fibers: provide flexibility trachea can stretch/relax while breathing
- cartilage rigs: prevents trachea from collapsing on itself
trachealis
smooth muscle tissue of trachea
controls diameter
sympathetic: relax to increase diameter
parasympathetic: contract to decrease diamter
bronchi
allow air to reach the respiratory zone
terminal bronchioles
smallest bronchioles in conducting zone
reach respiratory zone
lungs
organ where external gas exhange occurs
hilum
the point at which the bronchi and any blood/nerve supply leave/enter the lung
blood supply to the lungs
pulmonary circulation
bronchial circulation
pulmonary circulation
pulmonary arteries bring oxygen-poor blood to the lungs
pulmonary veins move oxygenated blood away from the lungs
pulmonary capillary network: immediately surround alveoli
bronchial circulation
bronchial arteries supply lung tissue w oxygenated systemic blood
innervation of lungs
nerve fibers enter the lung at the pulmonary plexus
pleurae
thin double-layer serous membrane
visceral pleura: covers external lung features
parietal pleura: covers the thoracic wall and upper portion of the diaphragm
pleural fluid: fills the cavity between the 2 allows the pleura to stick
benefits of each lung having its own pleura
creates chambers for each lung
1. as organs move and shift while breathing: pleura slide over one another
2. prevents the spread of infection from one organ to another
respiratory bronchioles
Extend from the terminal bronchioles of the respiratory zone
lead into alveolar sacs composed of multiple indivudal alveoli
walls of alveoli
simple squamous epithelia: easy for gas exchange
are covered w capillary beds: gas exchange occurs via diffusion
individual alveoli connected to neighbors via alveolar pores: share air w one another
cell types of alveoli
- type 1 alveolar cells
- type 2 alveolar cells
- alveolar macrophage
type 1 alveolar cells
squamous epithelial cells
create walls of alveoli: where gas exchange occurs
type 2 alveolar cells
cuboidal cells scattered among type 1
secrete: surfactant- detergent-like substance which prevents walls of alveoli from sticking together
antimicrobial proteins: innate immunity
alveolar macrophages
mobile cells
consume pathogens, debris and protect internal alveolar surfaces
2 processes involved in respiratory physiology
- pulmonary ventilation
- gas exchange
pulmonary ventilation
the flow of air into and out of the lungs
air flows according to a pressure gradient
high to low
gas exchange
The exchange of respiratory gases across the alveolar wall
respiratory gases can move from air space in the lungs to blood or vice versa
3 gas laws influences these 2 processes
- Boyles law
- daltons law of partial pressures
- henrys law
boyles law
pressure and volume are inversely related—when one increases, the other decreases
volume of a container increases
pressure decreases
volume of a container decreases
pressure increases
changing the volume of the lungs
changes pressure within the lungs
pressure in lungs is described in relation to
atmospheric pressure (Patm)
at sea level Patm is
760 mm Hg
Intrapulmonary pressure (Ppul)
pressure inside the alveoli
inspiration
initiated by contraction of inspiratory muscles
1. diaphragm: during contraction, diaphragm flattens
thoracic cavity becomes larger
2. intercostal muscles: external intercostal muscles pull ribs up and outward
thoracic cavity becomes larger
volume of lungs increases
intrapulmonary pressure lower than atmospheric pressure
air flows into the lungs along the pressure gradient
volume of lungs decreases
intrapulmonary pressure increases higher than atmospheric pressure
air flows out of the lungs along the pressure gradxient
respiratory volumes
the amount of air that can be pushed into/out of the lungs during ventilation
tidal volume
normal volume of air that moves into and out of lungs during normal breathing
500 ml air
inspiratory reserve volume
amount of air that can be forcibly inspired past a normal tidal volume
2100-3000 ml air
expiratory reserve volume
amount of air that can be forcibly expired past a normal tidal volume expiration
1000-1200 ml air
residual volume
amount of air remaining in the lungs after forced expiration
1200 ml air
respiratory capacities
the sum of two or more respiratory volumes
inspiratory capacity
the total amount of air that can be inspired after a normal tidal volume expiration
IC= TV+IRV
vital capacity
the total amount of exchangeable air
VC= TV+ IRV+ERV
functional residual capacity
amount of air remaining in the lungs after a normal tidal expiration
FRC= RV+ ERV
total lung capacity
the total amount of air the lungs can hold after a maximal inhalation
TLC= IRV+ TV+ ERV+ RV
dead space
air that fills the conducting zone but never contributes to gas exchange
anatomical dead space
for a healthy individual - 150 ml of air
1 ml of air per pound of ideal body weight
alveolar dead space
air reaches the alveoli but no gas exchange occurs
total dead space
anatomical dead space+ alveolar dead space
non useful volumes
