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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
Q

High O2 demands

A

SNS dominates when ventilatory demand is increased
norepinephrine and epinephrine from adrenal medulla -> stimulates B2 receptors on bronchial smooth muscles -> increase airway radii (bronchodilation)

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26
Q

Pulmonary volumes and capacities

A

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)

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27
Q

Tidal volume (TV)

A

volume of air entering or leaving lungs during a single breath 500ml

28
Q

inspiratory reserve volume (IRV)

A

extra volume of air that can be maximally inspired over and above the typical resting tidal volume 3000ml

29
Q

Inspiratory capacity (IC)

A

Maximun volume of air that can be inspired at the end of a normal quiet expiration (IC=IRV + IV) 3500ml

30
Q

Expiratory reserve volume (ERV)

A

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
Q

Residual volume (RV)

A

Minimum volume of air remaining in the lungs even after a maximal expiration 1200ml

32
Q

Functional residual capacity (FRC)

A

volume of air in lungs at end of normal passive expiration (FRC = ERV + RV) 2200ml

33
Q

Vital capacity (VC)

A

Maximum volume of air that can be moved out during a single breath following a maximal inspiration (VC = IRV + TV + ERV) 4500ml

34
Q

Total lung capacity (TLC)

A

Maximum volume of air that the lungs can hold (TLC = VC + RV) 5700ml

35
Q

Forced expiratory volume in one second (FEV1)

A

Percentage of air expired during the first second of expiration >80%

36
Q

Minute (Pulmonary) Ventilation

A

Volume of air breathed in and out in 1 minute
=Tidal volume X respiratory rate
= 500ml/breath X 12 breaths/min
= 6000ml/min

37
Q

Anatomic dead space

A 
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
Q

the two steps in respiration

A

ventilation and perfusion

39
Q

ventilation(V)

A

movement of air into alveoli

40
Q

Perfusion(Q)

A

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
Q

Ventilation-perfusion (V/Q) ratio

A

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
Q

matching of air and blood

A

air in alveoli must patch blood in capillary

alveolar dead space + anatomic dead space = physiological dead space

43
Q

shunts

A

some alveoli are perfused but not ventilated

44
Q

alveolar dead space

A

some alveoli are ventilated but not perfused

small in healthy lungs

45
Q

Step 2

A

exchange of O2 and CO2 between air in alveoli and blood in pulmonary capillaries

46
Q

step 4

A

exchange of O2 and CO2 between cells and blood

47
Q

Exchange in steps 2 and 4 takes place by

A

process of simple diffusion

down the partial pressure gradient

48
Q

Step 3

A

transport of gases by the blood between lungs and cells

49
Q

Diffusion of gases depends on

A

partial pressure of gas across membrane

resistance to diffusion of gas across membrane

50
Q

Factors that affect the rate of gas exchange

A

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
Q

Step 2: gas exchange in lungs

A

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
Q

Step 4 gas exchange at cell level oxygen diffusion

A

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
Q

Step 4 gas exchange at cell level carbon dioxide diffusion

A

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
Q

Step 3 transport in the blood oxygen transport

A
  1. 5% combined with Hgb inside erythrocyte

1. 5% dissolved in plasma

55
Q

Step 3 transport in the blood carbon dioxide combines with water to form carbonic acid

A 
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
Q

Hemoglobin

A

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
Q

Control of respiration

A

Pons and medulla

58
Q

Control of respiration by central receptors

A

generating inspiratory/expiratory rhythm, rate & depth of breathing
modifying respiratory activites

59
Q

medulla respiratory centre

A

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
Q

Two types of peripheral receptors

A

mechanical and chemical

61
Q

Mechanical receptors

A

lung and chest wall receptors that detect changes in pressure, flow, or displacement of a structure

62
Q

Chemical receptors

A

peripheral chemoreceptors signal in aorta and carotid bodies impact medulla respiratory centre
Decreased arterial PO2
increased arterial PCO2
H+

63
Q

peripheral chemoreceptors

A

carotid bodies located in carotid sinus
aortic bodies located in aortic arch
respond to specific changes in chemical content of arterial blood

64
Q

Non-gas exchange factors that influence ventilation

A

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
Q

Tension pneumothorax

A

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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