Pulmonary Mod. 2 Ventilation Flashcards
Ventilation
MECHANICAL PROCESS by which ambient air is brought into and exchanged with air in the lungs
Respiration
GAS EXCHANGE. That occurs in lungs (alveolar/capillaries) and throughout the body
Ventilation rate
of breaths per minute
Alveolar Ventilation
volume of air that reaches alveoli per minute
Dead Space Ventilation
volume of air that DOES NOT reach alveoli per/min
Respiratory Center in Brain stem
Dorsal Respiratory group in medulla (DRG)
ventral respiratory group in medulla (VRG)
Pneumotaxic & Apneustic Centers Centers in Pons
DRG
Action–inspiratory
Function: autonomic rhythm of breathing
receives input from respiratory centes (periphral, chemo, central, lung receptors)
mechanism for blood CO2 and O2 levels to influence rate of ventilation
VRG
Action– inspiratory & expiratory
Function: active when increased ventilation is required (not acitve during rest)
Pneumotaxic & Apneustic Center in Pons
modify depth and rate of resp.
What can override autonomic control?
motor cortex, hypothalmus & limbic system (stress/emotion)
4 Lung Receptors
1) send impulse to DRG to influence Ventilation
2) Irritant Receptors
3) Stretch receptors
4) J-receptors
Irritant Receptors In Lung
located in epithelium of conducting airway
stimulated by noxious gas, particles,
action–cough reflux, bronchioconstriction, increased ventilation rate
Stretch Receptor In Lung
located in smooth muscle of cunducting
Stimulus–prevents over inhaling esp newborns (hering-breuer expiratory reflux)
Action–decrease ventilation
J-Receptors of Lung
located near alveolar septum of capillaries
Stimulus–elevated pulmonary capillary pressure
Action–rapid shallow breathing, decrease HR & BP
Chemoreceptors
central&peripheral chemoreceptors monitor pH,PaCO2, PaO2
Central Chemoreceptors
located in brainstem close to respiratory centers.
monitor physiology majority of the time (healthy conditions)
Stimulus for Central Chemoreceptors
detect changes in pH levels of CSF
CO2 diffuses into CSF, CO2 binds w/ H20=H2CO3 which disassociates into H+ and HCO3, and H+ in CSF decreases pH which is recognized
Action of Central Chemoreceptor
if PaCO2 increases, stimulates respiratory center to increase ventilation
Peripheral Chemoreceptor
located in Carotid (at birfurcation of ICA&ECA) and aortic bodies (aortic arch)
Stimulus & Action of peripheral Chemoreceptor
Stimulus–changes in PaO2
Action–increased ventiltion via DRG
Which chemoreceptors are more sensitive?
the CENTRAL CHEMORECEPTORS are more sensitive to increased PaCO2 than the peripheral will be to decreased PO2
Muscles involved in Inspiration
Rest: diaphragm+external intercostals
Exercise/Disease state–accessory, SCM, scalenes
Muscles involved in Expiration
Rest: none, elastic recoil
Exercise/Disease-acessory muscles, abd and internal intercostals
Surfactant’s role in the mechanics of breathing
lowers surface tension (allows alveoli to expand)
What pressure gradients drive gas exchange
higher O2 pp in alveoli vs pulmonary capillaries (promotes O2 diffusion into blood)
Higher blood stream CO2 pp in pulmonary capillaries vs alveoli (promotes CO2 diffusion into alveoli)
Tidal Volume (TV)
500ml
volume of air inspired/expired w/normal breath
Inspiratory Reserve Volume (IRV)
3,000-3,300ml
volume of air that can be inspired over/above TV (used w/exercise)
Expiratory Reserve Volume (ERV)
1,000-1,2000ml
volume that can be expired after expiration at tidal volume
Reserve Volume (RV)
1,200ml
Volume of air that remains in the lungs after maximal expiratrion
(cant be measured by spirometry)
Forced Vital Capacity FVC
4,500-5,000ml
TV+IRV+ERV+=VC (maxing out inspiration/expiration)
Total Lunch Capacity (TLC)
5,700-6,200
sum of all 4 lung volumes
Normal FEV1/FVC
70%-90%
Abnormal FEV1/FVC
less than 70
greater than 90
What kind of pathology would make the FEV1/FVC less than 70%
obstructive disease
What kind of pathology would make the FEV1/FVC more than 90%
restrictive disease, fibrotic pathology, alveoli cant stretch as much, so it actually pushes the air out qucker
Minute Ventilation (Ve)
RRxTV
(respiratory rate x tidal volume)
at rest approx 6L
(12respX500mL)=6L
Max Ve (maximum minute ventilation)
max volume of air moved in/out of lungs during exercise
healthy: 60-70% of MVV
can be as high as: 100-200L
FEV1 to FVC Ratio
percentage of FVC that can be expired in one second
Percentage of O2 in Trachea
20.9%
Partial Pressure of CO2 in Trachea
.03%
Partial Pressure of O2 in Alveoli
14.5%
Partial Pressure of CO2 in Alveoli
5.5%
