respiratory system

Question 1

what are some non-respiratory functions of the respiratory system?

Answer 1

defense against microbes
formation of sound
trapping and dissolving of blood clots
ventilation of the airways contributes to body heat and body water loss

Question 2

parietal vs visceral pleura

Answer 2

parietal- lining of chest wall
visceral- lines the surface of the lungs

Question 3

conducting vs respiratory zone?

Answer 3

conducting zone- dead air space, where the movement of air in and out of the lungs occurs
respiratory zone- where has exchange takes place

Question 4

what are the opposing forces between the lungs and the chest wall in breathing?

Answer 4

lungs have elastic elements- inwards recoil
chest wall has inherent elasticity- recoils outwards
= generation of negative pressure within pleural space called intrapleural pressure

Question 5

what pressures are occuring during inspiration?

Answer 5

1- inspiratory intercostal muscles contract
2- thorax expands
3- intrapleural pressure gets more negative
4- transpulmonary pressure increases from 4 to 7, lungs expand
5- alveolar pressure changes from 0 to -1 at mid inspiration
6- pressure in the alveoli lower then the atmosphere so air wants to flow into the lungs
7- end of inspiration alveolar pressure= 0, no more movement occurs.

Question 6

what pressure changes occur during expiration?

Answer 6

expiration is a passive process and requires no muscle contraction
forced expiration uses expiratory muscles
1-inspiratory muscles relax
2- thorax shrinks, pulled by elastic recoil of lungs
3- intrapleural pressure rises -7 to -4 (less pull out on the lungs, transpulmonary pressure decreases
4- alveolar pressure increases
5- pressure in alveolar greater then in atmosphere so the air wants to move out of the lungs
6- alveolar pressure at the end is 0

Question 7

what is the alveolar volume equation?

Answer 7

alveolar volume= tidal volume- anatomical dead space

Question 8

minute ventilation equation
dead space ventilation equation
alveolar ventilation equation

Answer 8

tidal volume x frequency of breathing
dead space x frequency of breathing
(tidal volume- dead space) x frequency of breathing

Question 9

how does deep slow breathing alter alveolar ventilation?

Answer 9

increased tidal volume, decreasing frequency of breathing rate which decreases dead space ventilation therefore increasing alveolar ventilation

Question 10

high lung compliance=

Answer 10

large volume change

Question 11

pro and con of high lung compliance
give an example of a disease that has high compliance

Answer 11

con- elastic recoil of the lung is reduced
pro- easy to inflate the lungs (little activity of respiratory muscles required)
emphysema- destruction of alveoli, lungs tend to remain inflated and expiratory muscle activity required to deflate the lungs

Question 12

pro and con of low lung compliance
example of disease that has low compliance

Answer 12

pro- high elastic recoil, passive recoil of lungs not a problem
con- diffucult to inflate the lungs (strong inspiratory muscle activity required)
pulmonary fibrosis- fibrotic material, low compliance, lung volume decreased, patient will breath shallowly and rapidly

Question 13

what are the determinants of lung compliance and which has more impact?

Answer 13

1- elastic elements in the alveolar interstitium
2- surface tension between air and a layer of fluid on the wall of the alveolis **this one plays more of an impact on lung compliance

Question 14

what is surfactant and what produces it?

Answer 14

surfactant is a secretion that reduces surface tension
secreted by type II alveolar cells
increases lung compliance

Question 15

what are the determinants of airway resistance?

Answer 15

1- viscosity of the air (low because of low density gas)
2- length of the airways (fixed)
3- diametre/radius of the vessel

Question 16

what does changing the radius of the airways do to airway resistance

Answer 16

increased radius- reduced airways resistance
decreased radius- increases airway resistance

Question 17

how does asthma (chemical factor) impact radius of the airways?

Answer 17

1- blockage my mucus decreases the radius of the airways- increasing airway resistance
2- local inflammatory chemical mediators (ie histamine) cause smooth muscle to contract (bronchoconstriction)
increase restriction, decrease alveolar ventilation, reduced gas exchange

Question 18

what does stimulation of the parasympathetic nerves do the the smooth muscle of airways>

Answer 18

causes bronchoconstriction

Question 19

at steady state the volume of oxygen consumed by the cells is ____ the volume of oxygen entering the pulmonary capillaries from the alveoli

Answer 19

equal to the
same for CO2, rate of CO2 production by tissue cells equals the rate at which carbon dioxide enters the alveoli and is expired

Question 20

where is the highest value of O2 and Co2 in the blood circulation?

Answer 20

oxygen concentration highest in the arterial blood
carbondioxide concentration highest in the venous blood

Question 21

what is the respiratory quotent, what is a typical value for it
what can change RQ

Answer 21

rq= carbon dioxide produced/ oxygen consumed
0.8- typical value for a normal mixed diet
fat primary fuel= 0.7
protein cellular fuel =0.8

Question 22

partial pressure of gas is _________ ________ to its concentration of fractional content

Answer 22

directly proportional

Question 23

what value is atmospheric pressure and what makes up this value?

Answer 23

760mmHg
sum of partial pressures in the atmosphere= atmospheric pressure

Question 24

what are the three factors that affect partial alveolar pressure for oxygen?

Answer 24

1- how much oxygen are we breathing in
2- alveolar ventilation- how much fresh air is getting into the alveoli
3- volume of oxygen consumed- how much oxygen is being used by the body

Question 25

if you use more oxygen (VO2 up) PAO2 ____

Answer 25

decreases if you use more oxygen then the amount of oxygen in the alveoli decreases

Question 26

if you increase your breathing (increased alveolar ventilation) PAO2 ____

Answer 26

increases more ventilation of the lungs= more oxygen in the alveoli

Question 27

what is the 4 parametres that rapid diffusion of O2 and Co2 rely on?

Answer 27

1- diffusion properties of O2 and CO2 2- thin walls of the alveoli 3- large alveolar surface area for gas exchange to occur over 4- partial pressure difference for O2 and CO2

Question 28

true or false: CO2 has a larger diffusion constant then O2 as CO2 is much more soluble in plasma then O2

Answer 28

true

Question 29

why is there overall not much difference in the overall rate of diffusion between oxygen and carbon dioxide?

Answer 29

although carbon dioxide has a much larger diffusion constant compared to oxygen- carbon dioxide has a much lower partial pressure gradient which balances them out and not much difference in overall diffusion rate

Question 30

what effect does pulmonary oedema have on diffusion

Answer 30

increases diffusion distance= reduced rate of oxygen diffusion

Question 31

what effect does interstitial fibrosis have on diffusion

Answer 31

increased diffusion distance- thickening of alveolar wall reduces rate of oxygen diffusion

Question 32

what impact does emphysema have on diffusion?

Answer 32

destruction of the alveolar walls, decreased surface area for diffusion and reduced number of pulmonary capillaries

Question 33

what occurs to the airflow with decreased blood flow to a region of the lung in ventilation perfusion mismatching?

Answer 33

decreased partial pressure of carbon dioxide in the alveoli bronchioles will constrict decreased airflow - diverting airflow away from the area of lung with disease to healthy area of lungs to increase perfusion ventilation matching

Question 34

what occurs to the blood flow with decreased airflow to a region of the lungs?

Answer 34

decreased partial pressure of oxygen in the pulmonary blood vasoconstriction of pulmonary vessels decreased blood flow (to match decreased airflow) diversion of blood flow away from local area of disease and towards a healthy area of the lungs

Question 35

what are the two transport mechanisms for oxygen in the blood? what form is it mostly found in?

Answer 35

dissoloved in plasma bound to haemglobin **note only the oxygen dissolved in plasma is responsible for the partial pressure of oxygen in the blood

Question 36

how does oxygen bind to hb?

Answer 36

oxygen binds to the haem part- 4 oxygen molecules per hb molecule. oxygen binds through cooperative binding, the more oxygen that is bound makes it easier for the next oxygen to attatch

Question 37

what is the oxygen saturation of arterial vs venous blood?

Answer 37

arterial= 98% venous= 75%

Question 38

what occurs to blood oxygen in an anemic patient?

Answer 38

they have lower hb concentrations which means they have a decreased capacity to carry oxygen they can still have 100% saturation but they amount of oxygen they carry is less because they have less hb in the blood

Question 39

in a oxygen HB dissociation curve what does the steep slope favour?

Answer 39

favours offloading of oxygen in areas of the body that have a low partial pressure of oxygen

Question 40

in a oxygen HB dissociation curve what does the flat portion favour?

Answer 40

flat slope favours the loading of oxygen onto HB in high partial pressures of oxygen helps to maintain oxygen saturation at high altitude or for someone with lung disease

Question 41

factors that cause an increased affinity for HB cause a ____ in p50 and a _____ shift of the curve which favours the _____ of oxygen and HB

Answer 41

decrease leftwards loading "increased oxygen attraction"

Question 42

any factor that causes a decreased affinity of HB for oxygen causes an ____ in p50 which causes the curve to shift to the ____, this favours the _____ of oxygen and HB

Answer 42

increased right relased of oxygen from hb "lower oxygen attraction"

Question 43

describe how the bohr effect impacts the efficient hb function

Answer 43

the affinity of oxygen is dependent on carbon dioxide and hydrogen concentrations ie in the lungs where there is low carbon dioxide levels it favours the loading of oxygen in metabolising tissues where there is high concentrations of carbon dioxide it favours the offloading of oxygen

Question 44

what are the three forms that carbon dioxide is transported through the blood in what what form does it mostly travel in?

Answer 44

1- dissolved in the plasma 2- bound to hb in the erythrocytes forming carboamino compounds (co2 binds to the globin part of the haemoglobin) 3- in the form of bicarbonate ion *mostly travels in the form of bicarbonate ion (60%) **only co2 dissolved in plasma is responsible for the partial pressure of co2 in the blood

Question 45

where does the conversion of carbon dioxide to bicarbonate occur and through what enzyme is this?

Answer 45

carbon dioxide conversion occurs in the erthrocytes through a enzyme called carbonic anhydrase

Question 46

when a bicarb moves out of the rbc down its concentration gradient a ___ ion moves ____ the rbc to maintian electroneutrality ___ moves ___ rbc to maintain osmolarity

Answer 46

cl- moves into the rbc to maintain electroneutrality h20 moves into rbc to maintain osmolarity

Question 47

In the haldane effect what occurs to the curve when the partial pressure of oxygen is low

Answer 47

the co2 curve is shifted up and to the left (reduced p50) this effect is for the removal of carbon dioxide from tissues

Question 48

in the haldane effect what occurs to the curve when the partial pressure of oxygen is high?

Answer 48

the co2 curve is shifted down and to the right this means carbon dioxide binds less readily to globin promotes the release of carbon dioxide from haemoglobin ( ie in the lungs to get rid of the carbon dioxide through respiration)

Question 49

haldane vs bohr effect

Answer 49

bohr effect =the effect that carbon doxide has on oxygen carriage haldane effect= the effect oxygen has on carbon dioxide binding to haemoglobin

Question 50

how does haemoglobin buffer hydrogen ions

Answer 50

deoxyg hb has greater affinity for H+ then oxyhb does so it binds H+ ions that are produced by metabolism then the blood passes through the lungs these reactions are reversed

Question 51

hypoventilation leads to respiratory ______ this causes retention of _____ in the blood this increase drives the reaction to the _____ and an increase in ____ causes a ____ in pH

Answer 51

hypoventilation where you are breathing less- means you breath less carbon dioxide out causing... acidosis co2 right H+ drop (more acidic)

Question 52

hyperventilation will lead to respiratory _____ this causes increased ___ of ___ from the blood reduced ___ drives the reaction to the ____ the ___ levels in the blood will fall and an ____ ph will occur

Answer 52

alkalosis increased loss of CO2 from the blood less co2 drives reaction to the left the hydrogen levels in the blood will fall and increased ph will occur (alkalosis)

Question 53

neurons in the inspiratory centre _____ discharge vs neurons in the expiratory centre _____ discharge

Answer 53

inspiratory neurons- spontaneously discharge to induce muscle contraction of inspiratory muscles expiratory neurons don't discharge spontaneously, expiration is a passive process and doesnt typically require muscle activity

Question 54

involuntary control of breathing vs voluntary control of breathing?

Answer 54

involuntary control occuring through the medulla oblongata containing the expiratory and inspiratory centres voluntary control of breathing bypasses the medulla and the cerebral cortex directhly sends information to the spinal cord

Question 55

what is the role of nucleus tractus solitarius in breathing>

Answer 55

recieves sensory information from mechano&chemoreceptors these cause reflex adjustment in breathing response to things such as exercise, airway irritants or environmental changes

Question 56

where are the peripheral chemoreceptors located?

Answer 56

aoritc arch and body - signal through the vagus nerve carotid bodies signalling via the glossopharyngeal nerve

Question 57

an increase in firing of peripheral chemoreceptors causes an ___ in ventilation

Answer 57

increased

Question 58

what conditions of Po2, Pco2 or H+ concentration cause increased firing from peripheral chemoreceptors?

Answer 58

decreased oxygen= hypoxia increased carbon dioxide= hypercapnia increase in arterial H+ concentration= acidosis

Question 59

where are the central chemoreceptors located what are they senstive and what are they insensitive to?

Answer 59

located in the medulla oblongata insensitive to- hypoxia, arterial acidosis (as H+ cannot cross blood brain barrier) sensitive to concentration of H+ in the brain extracellular fluid this is because co2 converted to H+ ions this detection increases ventilation

Question 60

ventilation response only occurs when arterial Po2 falls below ____

Answer 60

60mmHg this is because up until this level haemoglobin is still mostly fully saturated

Question 61

are central or peripheral chemoreceptors more prominant when it comes to hypercapnia ventilation response?

Answer 61

central chemoreceptors play a bigger role due to more carbon dioxide in fluid around the brain small increases to pco2= large increases in ventilation

Question 62

how does ventilation change in response to metabolic acidosis?

Answer 62

increased H+ production detected by chemoreceptors response through hyperventilation co2 is blown off reducing arterial concentration of co2.

Question 63

how does ventilation change in response to metabolic alkalosis?

Answer 63

loss of H+ ions through vomiting low H+ levels detected by peripheral chemorecptors = reduced ventilation hypoventilation increases Pco2 which leads to formation of H+ ions