MCAT Biology Ch8: Respiration Kap Flashcards
lungs
- where gas exchange occurs
- primary function - movement of gas in the lungs
air pathway
enters resp tract through external nares of nose (mouth and nose warm and humid air before into lungs)–> nasal cavity, filtered through mucous membranes and nasal hairs, cilia (so don’t breathe in lungs) –> pharnyx –> larnyx –> cartilaginous trachea –> mainstream bronchi –> bronchioles –> alveoli
external nares
air enters resp tract here first
larynx
- only for air
- opening of it (glottis) is covered by epiglottis during swallowing
pharnyx
between mouth and esphoagus where food travels
epiglottis
covers glottis during swallowing
trachea
-air passes here from larynx, then into bronchi
–ciliated epithelial cells to catch material that pasted nose
bronchi
- one per side
- air comes from trachea
- divided into bronchioles, where air goes
- ciliated epithelial cells to catch material that pasted nose
bronchioles
- smaller structures divided from bronchi, which air comes from
- air goes to alveoli
alveoli
- tiny structures in which gas exchange occurs
- air comes from bronchioles
- each alveolus coats w/ surfactant –> lowers surface tension and prevents alveolus from collapse
- network of caps surrounds each to carry O2 and CO2
- branching and min. size –> large SA for gas exchange (100 m2)
surfactant
detergent that lowers SA and prevents alveolus from collapse
thoracic cavity
- lung are in here
- also contains heart
- separated from organs of digestion by muscle known as diaphragm
diaphragm
- muscle separates thoracic cavity from organs of digestion
- necessary for inspiration
- composed of skeletal muscle –> somatic control
- chest wall forms one side
inspiration
diaphragm is necessary for this
pleurae (sing. pleura)
- membrane surrounds each lung
- closed sac against which lung grows
visceral
- surface against lung
- inner
parietal
- all other parts of sac (pleura)
- outer, assoc w/ chest wall
intrapleural space
- space w/in space (between visceral and parietal)
- contains thin layer of fluid
- helps lubricate two pleural surfaces
- pressure differential between it with lungs –> for proper respiration
stages of ventilation
- pressure –> work
- pressure differentials between lungs and intrapleural space to drive air into lungs
- inhalation and exhalation
inhalation
- active process
- use diaphragm and external intercostal muscles to expand thoracic cavity
- cavity enlarges –> diaphragm flattens down –> chest wall moves out –> intrapleural vol increase (dec pressure) –> lungs (atm) sucks in higher pressure (outside air) –> expand
external intercostal muscles
- used during inhalation to expand thoracic cavity
- layers of muscles between ribs
negative-pressure breathing
- during inhalation
- driving force is lower (relatively neg) pressure in intrapleural space compared w/ lungs (alveoli)
exhalation
- doesn’t have to be active process
- diaphragm and external intercostals relax –> chest cavity dec in size (vol) –> intrapleural space pressure down vol (inc. pressure) –> air pushed out –> exhalation
- surfactant prevents complete collapse of alveoli during exhalation by reducing surface tension at alveolar surface
internal intercostal muscles
-highly active tasks –> speed process using this which opposes externals and pull rib cage down –> actively dec vol of thoracic cavity
control of ventilation
- breathing requires input from nervous control center
- primarily regulated by neurons; primarily sensitive to carbon dioxide conc; CO2 rise –> resp. rate will inc. to counter
-limited extent to control our breathing through cerebrum
-hypoventilation - inc. CO2 levels and override by medulla
-hyperventilation - blow too much CO2 and inhibit ventilation
(low level O2 –> hypoxia drive ventilatory response)
ventilation centers
ventilation primarily regulated by neurons in the medulla oblongata, rhythmically fire to cause regular contraction of respiratory muscles
chemoreceptors
- how CO2 conc are measured
- neurons’ surfaces monitor changes in blood’s pH
total lung capacity (TLC)
–healthy = 6 to 7 liters
-breathe in –> total amount of air in lings at this point
spirometer
- instrument to assess lung capacities
- measure amount of air normally present in lungs and rate which ventilation occurs.
- normal respiration - 12 breaths/min
- higher elevation –> ventilation may inc.
vital capacity (VC)
-breathe out until we cannot breathe out –> total amount forced out
residual volume (RV)
-left over air in lung (expelling all –> lung collapse)
TLC
VC + RV
tidal volume (TV)
air naturally comes out w/ exhalation
expiratory reserve volume (ERV)
-resp. muscles to push air out, the bit of air that exits
inspiratory reserve volume (IRV)
-extra air take in
VC
TV + ERV + IRV
gas exchange
-pulmonary cap. surrounds each alveolus (single-celled layer) –> bring deoxygenated blood from pulmonary arteries
left lung
has small identation => smaller lung, due to position of heart in the cavity
digestive system
also has villi and microvilli
pneumothorax
air in intrapleural space => inc. the pressure => lung collapse => needle to withdraw air
boyle laws
applies neg- pressure breathing
emphysema
destruction of alveolar walls => reduced elastic recoil of lungs
inhalation and exhalation
muscle contraction => neg. pressure in thoracic cavity => forces air in during inspiration => expiration => elastic recoil of lungs and musculature => during more active states => muscle used to force air out => speed ventilation
