ap respiratory system

functions

air passageway, O2/CO2 exchange, detection of odor, sound production, blood pH regulation, protection

external vs internal respiratory

external- respiratory and cardiovascular systems, gas exchange. O2 diffuses from alveoli into blood and co2 from blood into alveoli

internal- oxidative phosphorylation, ATP synthesis (at tissue level, cellular processes) o2 used to produce ATP and CO2 generated as byproduct and diffused in blood

nasal cavity

nostrils provide openings for air to enter/leave. upper portion has olfactory receptors, lined with mucous membrane w goblet cells- traps microorganisms and particles and sweeps towards pharynx via cilia to be swallowed and destroyed

upper vs lower respiratory tract

upper- conducting zone (larynx to lungs), transports air only, thick walls

lower- respiratory zone, site of gas exchange in lungs, thin walls

larynx

passageway for air, prevents ingested material from entering respiratory tract via epiglottis. produces sound as vocal cords vibrate, sneeze and cough reflex which removes irritants

bronchi

main tubes carrying area from trachea into lungs. branch off into smaller

primary- dont collapse, secondary-less cartilage, tertiary-branch, bronchioles- no cartilage, regulate air flow (smooth muscle)

trachea

windpipe, held open via bands of cartilage

effects of cigarette smoking

slow, progressive damage. slows and paralyzes cilia, causes dirt and pathogens to no longer remove from respiratory system- pathogens can then acesss respiratory surfaces and cause infection. irriate/inflame airway

smokers cough occurs when cilia lose function and excess mucus is produced which must be coughed up- can lead to chronic bronchitis

emphysema= chronic lung disease, alveoli damaged and lose elasticity causing reduced SA for gas exchange and traps air in lungs. causes shortness of breath, dec O2, lung damage

differences in parts of respiratory system as you go down

upper respiratory (larynx to lungs) responsible for conduction only. more cartilage, cilia, and goblet cells here

lower respiratory responsible for respiration and gas exchange, thinner walls, no cartilage or cilia or goblet cells as that would make gas exchange hard.

bronchi have less cartilage as they go down- cartilage keeps upper airway open and as it decreases smooth muscle increases which allows bronchioles to constrict/dilate to reg breathing

alveoli

primary site of gas exchange, 300 million in lung. 3 diff cells= thin epithelial cells (1), surficant-producing cells which prevent alveoli from collapsing as surficant reduces surface tension of fluid lining alveoli (ST typically causes them to collapse and stick together). (2) macrophages (3), surrounded by dense capillary network.

how gases are exchanged

diffision- flow from high to low concentration. mainly occurs in respiratory zone/membrane which has thin walls and a large surface

what makes air flow in and out of lungs

breathing is driven by pressure gradient, air moves from high to low pressure, p1p1=p2v2. (as v inc, p dec)

during inhalation, the diaphragm and intercostal muscles contract which increases the volume of the thoracic cavity. as volume inc, pressure in lungs decreases below atmospheric pressure and causes air to flow in

during exhalation, the diaphragm and intercostal muscles relax, decreasing the volume of the thoracic cavity. as volume decreases, pressure in the lungs increases above atmospheric pressure and causes air to flow out of the lungs

vital capacity, residual volume, and total lung capacity

vc- maximum volume of air that can be exhaled after taking the deepest possible breath

rv- volume of air remaining in lungs after max expiratory effect

tlc- total volume of air lungs can hold (VC+RV)

study chart!!

tidal volume, expiratory/inspiratory reserve

tv- volume of air moved in or out of lungs during a respiratory cycle

e/ir- max volume of air exhaled/inhaled in addition to TV

MRV- minute respiratory volume

volume of new air moved into respiratory passages each minute (TV x respiratory rate). reflects how well your respiratory system can meet O2 demands. higher=better O2 delivery to tissues

AVR- alveolar ventilation rate

volume of air reaching alveoli each minute, impacts concentration of O2 and CO2 in alveoli. important in representing actual amount of air reaching alveoli as air can remain in dead space and not be used in gas exchange

how O2 transported in blood

moves between blood and air via diffusion in respiratory membrane, moves from alveoli to blood at the same rate it is consumed by cells.

diffusion is driven by partial pressure which is the pressure exerted by a specific gas per minute. it causes o2 to diffuse from areas of high pressure in alveoli to low pressure in capillary where it binds to hemoglobin

how CO2 transported in blood

moves between blood and alveoli by diffusion which is driven by differences in partial pressure. diffuses from high pressure in blood to low pressure in alveoli.

moves from blood into alveoli at same rate it is produced by cells. in the blood most co2 transported in the form of bicarbonate which are more soluble. before diffusion into alveoli bicarbonate converts back into CO2 which diffuses to be exhaled

importance of HCO3- in blood (bicarbonate)

buffers H+ and keeps the pH at 7.4

how we get rid of too much acid

kidneys, secrete H+ (acid) into urine and reabsorb bicarbonate back into blood to act as base

lungs remove CO2 via increasing breathing rate to lower H+ as CO2 contributes to H+ formation via reaction w h2o

V/Q

described how well airflow matches blood flow in lungs

V= ventilation, air reaching alveoli

Q= perfusion, blood flow reaching alveoli

• these need to be balanced, low=not enough air compared to blood. high=not enough blood flow

gas excahnge in alveoli

gases move from high to low pressre/diffusion which is driven by differences in partial pressure

O2 moves from alveoli into blood as pp of O2 is higher in alveoli than capillary blood. binds to hemoglobin in blood

CO2 moves opposite, pp of CO2 higher in blood than alveoli, so CO2 diffuses from blood into alveoli to be exhaled

O2 dissociation curve for hemoglobin

describes how partial pressure of O2 affects hemoglobins ability to bind and release O2.

at a high PO2 (lungs) hemoglobin has high affinity for o2 and becomes nearly fully saturated (all hemoglobin sites have O2), allowing it to pick up O2

at low PO2 (tissues) hemoglobin’s affinity for O2 decreases, causing it to be released and delivered to cells in need

tissues w low metabolic activity have moderate PO2, so hemoglobin releases some O2 but it remains partially saturated. highly active tissues have very low PO2 so more O2 is released here

why hemoglobin is perfect

can transport 3 substances- O2 attached to iron in heme, CO2 and H+ ions attached to globin.

binding of each O2 causes conformational changes in hemoglobin which makes it easer for each additonal O2 to bind to iron.

delivers O2 exactly where it is needed most based on PO2, PCO2, acidicy, temp

primary stimuli for respiratory center

co2 and H+ ions (pH) if these increase breathing rate and TV increase to get rid of CO2 and increase pH to normal

carbon monoxide

binds to hemoglobin much stronger than O2 does, prevents O2 from binding and being transported. makes it hard for remaining o2 to be released from hemoglobin into tissues. causes oxygen deprivation