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Physiology 150 > Unit 8 - Respiratory Physiology > Flashcards

Unit 8 - Respiratory Physiology Flashcards

1
Q

Respiration

A

obtain O2 for use by body’s cells and to eliminate CO2

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2
Q

Two separate but related processes

A 
Internal respiration(cellular respiration, intracellular metabolic processes)
external respiration
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3
Q

External respiration

A

Breathing
Exchange of O2 and CO2 between air in alveoli and blood within the pulmonary capillaries
Transport of gases by the blood between lungs and tissue exchange of O2 and CO2 between tissues and blood

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4
Q

Getting smaller and smaller

A

tubes carry air between the atmosphere and alveoli
nasal passages -> pharynx -> trachea -> right and left bronchi to lungs-> lobar branches-> 2 respiratory bronchioles -> several alveoli for gas exchange

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5
Q

Structures of the pulmonary system

A

trachea, segmental bronchi, bronchioles, alveolar ducts

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6
Q

Trachea windpipe and larger bronchi

A

Non-muscular tubes with rings of cartilage preventing collapse

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7
Q

Bronchioles

A

no cartilage to hold them open

walls contain smooth muscle innervated by autonomic nervous system

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8
Q

alveoli

A

thin-walled inflatable sacs that function in gas exchange
walls consist of a single layer type I alveolar cells
pulmonary capillaries encircle each alveolus
epithelium contains type II alveolar cells (secrete pulmonary surfactant phospholipid)
lowers alveolar surface tension (increases pulmonary compliance, allows alveoli of different sizes to exist and remain open)

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9
Q

alveoli

A

alveolar macrophages guard lumen

pores of kohn permot airflow between adjacent alveoli collateral ventilation

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10
Q

the chest wall

A

outer chest wall thorax
12 pairs of ribs join sternum anteriorly and thoracic vertebrae posteriorly
protects lungs and heart
contains muscles that generate the pressure that causes airflow

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11
Q

pleural space

A

double-walled, closed sac separates each lung from thoracic wall
visceral(inner) layer covers lungs
parietal(outer) layer attached to chest wall
pleural cavity - interior of pleural sac
intrapleural fluid - secreted by surfaces of the pleura, lubricates pleural surfaces

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12
Q

respiratory mechanics

A

relationships among pressures inside and outside lungs important in ventilation
4 pressures

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13
Q

atmospheric/barometric pressure(Pb)

A

760mmHg

pressure exerted by weight of air in atmosphere on earths objects

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14
Q

Alveolar or intra-alveolar pressure(Palv)

A

pressure inside the alveolus
760mmHg when not breathing
negative (less than atmospheric) during inspiration and positive during expiration

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15
Q

Pleural or Intrapleural pressure (Pip)

A

pressure in pleural space

intra-pleural pressure= 756 (-4)

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16
Q

Transpulmonary/recoil pressure (Ptp=Palv-Pip)

A

pressure difference between alveolar pressure and pleural pressure
negative due to properties of lung and chest wall
lungs want to collapse
chest wall wants to expand
positive so keeps lungs and alveoli open

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17
Q

Step 1. Pulmonary ventilation main inspiratory muscles

A

external intercostal muscles(innervated by intercostal nerves)
diaphragm (dome-shaped sheet of skeletal muscle separates thoracic cavity from abdominal, innervated by phrenic nerve
accessory muscles

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18
Q

Expiratory muscles

A

expiration begins with relaxation of inspiratory muscles
relaxation of diaphragm and muscles of chest wall, plus the elastic recoil of the alveoli, decrease the size of the chest cavity
lungs are compressed intra-alveolar pressure increases
when pressure increases to level above atmospheric pressure, air is driven out - expiration occurs

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19
Q

factors influencing ventilation elastic recoil

A

how readily the lungs rebound after having been stretched

responsible for lungs returning to their pre-inspiratory volume when inspiratory muscles relax at end of inspiration

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20
Q

Factors influencing ventilation elastic recoil depends on two factors

A

Highly elastic connective tissue in the lungs
alveolar surface tension (thin liquid film lines each alveolus, reduces tendency of alveoli to recoil)
pulmonary surfactant(lipoprotein molecules secreted by type II alveolar cells, lowers alveolar surface tension)
(increases pulmonary compliance, reduces recoil presure of smaller alveoli, small and larger alveoli can co-exist, helps maintain lung stability)

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21
Q

factors influencing ventilation compliance

A

ability of lungs to stretch and expand
the less compliant the lungs are, more work required to produce a given degree of inflation
when compliance is high, lung is pliable and low elastic recoil
when compliance is low, lung is stiff and high elastic recoil

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22
Q

Air flow rate (F) depends on

A

difference between atmospheric and intra-alveolar pressure and the resistance of airways to airflow(R)
F = DeltaP/R

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23
Q

Controls contraction of smooth muscle in walls of bronchioles

A

ANS

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24
Q

During low O2 demands

A

PNS dominates when ventilatory demands are low

vagus nerve secretes Ach -> stimulates bronchiolar smooth -> decreases airways radii (bronchoconstriction)

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25
High O2 demands
SNS dominates when ventilatory demand is increased norepinephrine and epinephrine from adrenal medulla -> stimulates B2 receptors on bronchial smooth muscles -> increase airway radii (bronchodilation)
26
Pulmonary volumes and capacities
lung volume changes with different respiratory efforts recorded by spirometer forced expiratory volume in one second (volume of air that can be expired during 1st second of expiration)
27
Tidal volume (TV)
volume of air entering or leaving lungs during a single breath 500ml
28
inspiratory reserve volume (IRV)
extra volume of air that can be maximally inspired over and above the typical resting tidal volume 3000ml
29
Inspiratory capacity (IC)
Maximun volume of air that can be inspired at the end of a normal quiet expiration (IC=IRV + IV) 3500ml
30
Expiratory reserve volume (ERV)
Extra volume of air that can be actively expired by maximal contraction beyond the normal volume of air after a resting tidal volume 1000ml
31
Residual volume (RV)
Minimum volume of air remaining in the lungs even after a maximal expiration 1200ml
32
Functional residual capacity (FRC)
volume of air in lungs at end of normal passive expiration (FRC = ERV + RV) 2200ml
33
Vital capacity (VC)
Maximum volume of air that can be moved out during a single breath following a maximal inspiration (VC = IRV + TV + ERV) 4500ml
34
Total lung capacity (TLC)
Maximum volume of air that the lungs can hold (TLC = VC + RV) 5700ml
35
Forced expiratory volume in one second (FEV1)
Percentage of air expired during the first second of expiration >80%
36
Minute (Pulmonary) Ventilation
Volume of air breathed in and out in 1 minute =Tidal volume X respiratory rate = 500ml/breath X 12 breaths/min = 6000ml/min
37
Anatomic dead space
``` not all lung tissues used for gas exchange not all air gets to alveoli; remains in conducting airways TV = 500ml but only 350 ml reach alveoli Alveolar ventilation = (TV - DPV) X respiratory rate = (500 - 150) X 12 breaths/min = 350 X 12 = 4200ml/min ```
38
the two steps in respiration
ventilation and perfusion
39
ventilation(V)
movement of air into alveoli
40
Perfusion(Q)
exchange of O2 and CO2 affected by body position due to gravity minimal blood flow in apices of upright lung maximal infusion into lung bases (25% of vessels perfused)
41
Ventilation-perfusion (V/Q) ratio
for adequate gas exchange between air in alveoli and blood in pulmonary capillaries need V and Q to match. ensure air is delivered to lung regions where blood is going and vice versa. Normal ratio of V/Q is 0.8 (4/5L) affected by disorders in ventilation, perfusion or both
42
matching of air and blood
air in alveoli must patch blood in capillary | alveolar dead space + anatomic dead space = physiological dead space
43
shunts
some alveoli are perfused but not ventilated
44
alveolar dead space
some alveoli are ventilated but not perfused | small in healthy lungs
45
Step 2
exchange of O2 and CO2 between air in alveoli and blood in pulmonary capillaries
46
step 4
exchange of O2 and CO2 between cells and blood
47
Exchange in steps 2 and 4 takes place by
process of simple diffusion | down the partial pressure gradient
48
Step 3
transport of gases by the blood between lungs and cells
49
Diffusion of gases depends on
partial pressure of gas across membrane | resistance to diffusion of gas across membrane
50
Factors that affect the rate of gas exchange
as partial pressure gradient increases, rate of diffusion increases as surface area increases, the rate of diffusion increases increases in thickness of barrier separating air and blood decreases rate of gas exchange
51
Step 2: gas exchange in lungs
oxygen diffusion PO2 in alveoli = 100mmHg PO2 in pulmonary capillary = 40mmHg O2 diffuses from area of high alveoli to low partial pressure(pulmonary capillaries) until PO2 blood equilibrates with PO2 alveoli Carbon dioxide diffusion PCO2 in pulmonary capillary = 46mmHg PCO2 in alveoli = 40mmHg CO2 diffuses from area of high (pulmonary capillary) to low (alveoli) until PCO2 blood equilibrates with PCO2 alveoli
52
Step 4 gas exchange at cell level oxygen diffusion
PO2 in systemic capillary = 100mmHg PO2 in cell = 40mmHg O2 diffuses from area of high (capillary to low partial pressure (cell) until PO2 blood equilibrates with PO2 cell
53
Step 4 gas exchange at cell level carbon dioxide diffusion
CO2 partial pressure in systemic capillary = 40mmHg CO2 partial pressure in cell = 46 mmHg CO2 diffuses from area of high (cell) to low (alveoli) until PCO2 blood equilibrates with PCO2 cell
54
Step 3 transport in the blood oxygen transport
98. 5% combined with Hgb inside erythrocyte | 1. 5% dissolved in plasma
55
Step 3 transport in the blood carbon dioxide combines with water to form carbonic acid
``` dissociates into hydrogen ions and bicarbonate ion (the enzyme carboninc anhydrase) 80-90% bound to hemoglobin as bicarbonate (HCO3-) The reverse (bicarbonate ions forming CO2) in lungs ```
56
Hemoglobin
Binds with oxygen in blood fully saturated - all 4 Hg binding sites bound to oxygen & no sites available Partially saturated - some binding sites bound to oxygen and some sites available Unsaturated - no sites bound to oxygen and all sites available
57
Control of respiration
Pons and medulla
58
Control of respiration by central receptors
generating inspiratory/expiratory rhythm, rate & depth of breathing modifying respiratory activites
59
medulla respiratory centre
Dorsal respiratory group DRG inspiratory neurons fire-> cell bodies and axons in spinal cord dire->inspiration stop firing->expiration Ventral respiratory group VRG for active inspiration and expiration project directly onto and activate other muscles (tongue, upper airway)
60
Two types of peripheral receptors
mechanical and chemical
61
Mechanical receptors
lung and chest wall receptors that detect changes in pressure, flow, or displacement of a structure
62
Chemical receptors
peripheral chemoreceptors signal in aorta and carotid bodies impact medulla respiratory centre Decreased arterial PO2 increased arterial PCO2 H+
63
peripheral chemoreceptors
carotid bodies located in carotid sinus aortic bodies located in aortic arch respond to specific changes in chemical content of arterial blood
64
Non-gas exchange factors that influence ventilation
sneezing/coughing inhaling noxious agents may trigger cessation of breathing pain reflex stimulates respiratory centre various emotional states respiratory centre reflex inhibited during swallowing
65
Tension pneumothorax
traumatic origin from penetrating (stab wounds, GSW) or non-penetrating injury (rib fractures) also from iatrogenic causes CPR air enters pleural space during inspiration but cannot escape during exhalation air builds up in pleural space lung on ipsilateral same side collapses and forces mediastinum toward contralateral opposire side decreses venous return and cardiac output

Physiology 150 (11 decks)

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