Module 2 Pulmonary Flashcards
rate and depth
ventilation
define ventilation
mechanical process where air is brought into and out of lungs
define respiration
gas exchange in lungs at alveolar/capilaries
ventilation rate
12 breaths per min
minute ventilation
volume of air inspired/expired per min in L
6L per min at rest
minute ventilation = (alveolar ventilation + dead space ventilation
)*RR
alveolar ventilation
volume of air that reaches the alveoli per min
dead space ventilation
volume of air that does not reach alveoli per min
how many seconds for inspiration? expiration?
2 / 3
respiratory center in brainstem
controls contraction and relaxation of respiratory muscles DRG and VRG in medulla and pneumotaxic and apneustic centers in pons
dorsal respiratory group
in medulla-
primary inspiratory- tells diaphragm to contract
sets automatic rhythm of breathing
gets infput from respiratory receptors (peripheral and central chemoreceptors, lung receptors etc) - this is a mechanism for blood co2 and o2 levels to influence rate of ventilation
example of respiratory receptors that influence DRG
peripheral and central chemoreceptors and lung receptors
co2 and o2 can influence the rate of ventilation
ventral respiratory group (VRG)
inspiratory and expiratory actions when ventilation is required- otherwise the lazy brother during rest
pheumotaxic and apneustic centers
in pons
modify DGR and VGR depth and rate inspired
what can override automatic ventilation control?
other parts of cns! ex. motor cortex (voluntary movement), hypothalamus and limbic system (stress/emotion)
3 types of lung receptors
irritant, stretch, j-receptors
what do lung receptors do?
send impulse to DRG to influence rate of ventilation
irritant receptors
rapidly adapting
in epithelium of conducting airway (usually larger airway)
stimulated by noxious gas, particles etc
cause cough reflex, gasping, initiate bronchoconstriction of air way and increased ventilation rate/depth (hyperpnea = increase breathing)
stretch receptors
slowly adapting receptors
in smooth muscle of conducting airways
“hering-breuer reflex inflation reflex” - prevents over inflation of lung
stimulated by stretch (adults extreme tidal volume in exercise, or copd) or (new borns to maintain ventilation)
sends a signal via CN 10 to b brain stem to inhibit inspiration by prolonging expiration time and decreasing volume of ventilation
Juxtapulmonary capillary receptors (J-receptor)
near alveolar septum of capillaries
stimulated by elevated pulmonary capillary pressure (edema, pul embolism etc)
acts on DRG to stimulate inspiration (rapid shallow breathing), also will decrease HR, and decrease BP
(extreme situation can cause opposite effect: apnea-slow breathing)
name the chemoreceptors and locations
central chemoreceptors in brainstem near respiratory centers
peripheral chemoreceptors in carotid and aortic bodies (carotid a. and aortic arch)
central chemoreceptors
indirectly monitor co2 of arteres by monitorying the pH of CSF (h+)
receptors detect changes in pH levels - co2 can cross bbb but h+ can not, so co2 bibnds with h20 to get h2co3 which breaks into h+ and hco3…. so if co2 rises in CSF, then H+levels increase (causing pH to decrease) which increases ventilation! (to blow off co2)
peripheral chemoreceptors
monitor o2- if o2 is less then 60mmHg = hypoxmia= causes an increase in ventilation via DRG
sensitive to changes in o2 mainly
must be less then 60 otherwise central chemoreceptor will kick in first
peripheral vs central chemoreceptor - their important roles
peripheral - acclimatization in altitude (chronic hypoemia)
central - acid base balance
describe the relationship between central and peripheral chemoreceptors
co2 and ph levels are primary influence on ventilation in health condition. ex) decrease o2 by hypoventilation increases co2 which decreases ph =increase in ventilation
(central is more sensitive then peripheral)
peripheral would kick in if o2 fell below 60 mmHg
if unhealthy: chronic hypoventilation makes central chemoreceptors less sensitive so the peripheral takes over and regulates ventilation
