Respiratory physiology - ventilation and perfusion

Question 1

Does there have to be a pressure gradient for air to be drawn into the lungs

Answer 1

yes

Question 2

how is respiratory Air flow determined

Answer 2

by the pressure difference between the mouth and the alveoli ( in the lungs)
has to be a difference either increase p1 or decrease p2

flow results from either an upstream rise ( positive pressure breathing) or a downstream fall in pressure ( negative pressure breathing)

Question 3

what is positive pressure breathing

Answer 3

increase P1 at the mouth - creating positive pressure in relation to the lungs therefore forcing air in

assisted breathing

Question 4

what is negative pressure breathing

Answer 4

Decrease P2 relative to the atmosphere so you create gradient drawing air in

Question 5

what is normal ATM

Answer 5

750mmHg

Question 6

when you increase the pressure inside the lungs to create gradient and force air out
what is happening

Answer 6

expiration

Question 7

Pip

Answer 7

inter pleural pressure ( intrathoracic pressure)

Question 8

Palv

Answer 8

Alveolar pressure - pressure inside the alveoli

Question 9

Ptp

Answer 9

transpulmoanry pressure (Palv-Pip=Ptp)

Question 10

Patm

Answer 10

atmospheric pressure - pressure around us

Question 11

what happens in the mechanism of inspiration

Answer 11

inspiratory muscles contract
diaphragm goes flat
ribs up and out increasing thoracic cavity size

Question 12

what process
alveolar vol increase
Palv decrease
difference in pressure between alveolar and atm

inspriaotry muscles contract sp Pip more negative so increase difference

Answer 12

Inspiration

Question 13

what happens in the mechanism of expiration

what happens to Ptp

Answer 13

inspiratory muscles relax , chest wall decreases and goes down so the space between the two membranes decrease so Pip less negative so decrease ptp

Question 14

what to fibres are used in expiration in elastic recoils

Answer 14

elastin - twice its size

collagen fibres - 2/3 and retain

Question 15

As we know outer alveoli are affected by the change in inter pleural pressure - this in turn effects the next alveoli along the chain until it reaches the inner depth - what is this called

Answer 15

alveolar interdependence

Question 16

In a pneumothorax the pleural seal is broken - what does this mean

Answer 16

negative pressure cannot be generated as ventilation is ineffective , lung collapses - alveoli recoil layers can’t hold

Question 17

Resistance

Answer 17

resistance of respiratory tract to airflow during inspiration and expiration( predominantly expiration)

Affected by diameter of airways

Question 18

compliance

Answer 18

Measure of ability of the lungs to stretch and expand ( distensibility of elastic tissue)

Question 19

what is an obstructive disorder

Answer 19

increasing resistance going from a large entry point to small entry point - reduced diameter

Question 20

what is a restrictive disease

Answer 20

when the ability of expansion s reduced such as fibrosis as thicker lung tissue so have a lower compliance

Question 21

what is the conduction zone

Answer 21

conducts air breathed in that is filtered warmed and moistened by the lungs

Question 22

if radius is reduced by half what would the resistance be - knowing that r^4

Answer 22

16

Question 23

is resistance predominately an expiratory problem

Answer 23

yes

Question 24

what happens in emphysema

Answer 24

Destruction of the alveolar walls → large air spaces that are not cleared of air on exhalation ( air trapping)
Reduced elastic fibres as a result of destruction which then leads to a reduced elastic recoil
Characteristic “barrel chest”
Decreased gas exchange leads to reduced oxygen diffusion so reduced oxygen levels in the blood - blood vessels also destroyed with destruction of alveolar walls
Even mild exercise can cause breathlessness

Question 25

what can cause emphysema

Answer 25

farmers lungs | consistent exposure of irritants - smoke, dust chemicals and irritants and that roofs

Question 26

what causes the genetic version of emphysema

Answer 26

alpha 1 antitrypsin deficiency

Question 27

Principle Causes of COPD

Answer 27

emphysema and chronic bronchitis

Question 28

what cells secrete surfactant

Answer 28

type 2 alveolar cells - lipoprotein

Question 29

what does surfactant do

Answer 29

Lowers surface tension - increases compliance - less forces trying to bring the alveoli in making breathing easier Improves work of breathing

Question 30

ventilation of alveoli is

Answer 30

4-6L/min

Question 31

pulmonary blood flow of alveoli

Answer 31

Co= 4-6L/min Hr - beats per min SV is volume of blood ejected duringg each ventricular contraction CO- amount of blood pumped through circulatory system in one minute

Question 32

where is the greater ventilation and perfusion occur

Answer 32

at the bottom of the lung

Question 33

does regional V/Q vary and does it have a high impact on gas exchange

Answer 33

yes and no

Question 34

what is it called when no ventilation can reach area but pulmonary arterial blood can

Answer 34

shunt breathe in something

Question 35

when a pulmonary embolism occurs ( travels from somewhere else) and gets lodged you still have ventilation but no perfusion what is this called

Answer 35

alveolar dead space

Question 36

Stages involved in supply of oxygen and removal of carbon dioxide

Answer 36

Ventilation - gas exchange between atmosphere and alveoli External respiration - oxygen and carbon dioxide transfer between alveoli and blood Internal respiration - oxygen and carbon dioxide transfer between blood and tissue Gas transport - oxygen and carbon dioxide carried in blood between alveoli and tissues Cellular respiration - oxygen utilization and carbon dioxide production by tissues

Question 37

what is external respiration

Answer 37

oxygen and Co2 transfer occurs between alveoli and the blood

Question 38

what is internal respiration

Answer 38

oxygen and CO2 transfer is between the blood and the tissues

Question 39

In the upper division of the respiratory tree tidal flow is generated by what 1-16 ( conducting airways)

Answer 39

respiratory muscles

Question 40

in alveoli where respiratory exchange occurs and lower division of the respiratory tree 17-32 how is air moved

Answer 40

passive diffusion driven by partial pressure gradients

Question 41

daltons law

Answer 41

how gases move down their conc gradient by diffusion

Question 42

henrys law

Answer 42

how the solubility of a gas relates to its diffusion

Question 43

in daltons law gases move from a higher partial pressure to a lower partial pressure ATM 750mmHg PO2 is 157mmHg where does this occur

Answer 43

between alveoli and capillaries then later on between blood and tissue cells also atmosphere and lungs

Question 44

partial pressure in solution =

Answer 44

partial pressure in gas phase

Question 45

in external respiration - deoxygenated blood goes to oxygenated blood and the diffusion of gas is an independent process Alveolar air is P02 105mmHg PCO2 = 40mmHg what is the partial pressure of oxygen and carbon dioxide in deoxygenated blood coming towards alveoli

Answer 45

``` PO2 = 40mmHg PCO2 = 45mmHg ```

Question 46

in internal respiration exchange occurs between systemic capillaries and tissue cells - Oxygen-deoxy As we know oxygenated blood is PO2=100mmHg PCO2 = 40mmHg coming from the alveoli what is its levels in tissue cells

Answer 46

PO2=40mmHg | PCO2 = 45mmHg

Question 47

solubility of oxygen in plasma is low only 1.5% what carries oxygen to form Hb-O2

Answer 47

oxyhemoglobin

Question 48

How do we measure the partial pressure of oxygen

Answer 48

measure the oxygen dissolved in plasma - not carried by Hb

Question 49

Hb is a globin protein made of 4 polypeptides - 2 alpha and 2 beta - it has 4 haemolytic groups which has a porphyrin ring what ion is at the centre attached by 2 bonds ( 1st bond joins with oxygen molecule )

Answer 49

Fe2+ binding is reversible

Question 50

when fully saturated how many oxygen molecule does Hb carry

Answer 50

4

Question 51

on a O2 -Hb saturation curve which - Indicates that the saturation of Hb depends on the PO2 High PO2 → high saturation of HB from oxyhB Low PO2 → low saturation of Hb ( Hb + O2) this sigmoidal curve shows that the initial binding is difficult due to finding it but after a conformational change the next 2 can join - why is binding of the last oxygen so hard

Answer 51

full saturation is hard as oxygen has to find the last group

Question 52

how much oxygen can 1g of Hb hold

Answer 52

1.34ml

Question 53

At level of pulmonary capillaries what is the level of the partial pressure of O2

Answer 53

02 high partial pressur e of oxygen - most bound to HB

Question 54

At level of peripheral capillaries Is partial pressure of O2 low or high and why is this beneficial to the tissue?

Answer 54

partial pressure of oxygen is low, saturation of Hb flals rapidly - beneficial for tissue as allows cells to tke up unload O2

Question 55

in tissues that need more O2 the local environment moves the Hb-O2 curve to the right aidning unloading of O2 true or false

Answer 55

true

Question 56

what two products increase as a result of tissue metabolism

Answer 56

lactic acid and carbon dioxide

Question 57

carbonic acid is the product of water and carbon dioxide | produces what

Answer 57

proton and HCO3- decerases O2 carrying capacity

Question 58

what side does the curve shift to in Bohr effect as tissue environment

Answer 58

right | so Hb is less saturated and gives up oxygen more easily

Question 59

what side does the Bohr effect curve shift in the lungs and why

Answer 59

left | Hb can more easily bind to molecules of oxygen so more saturated - low Co2 conc environment

Question 60

In the foetus at the level of the umbilical vein which way does the Hb-O2 curve shift and why

Answer 60

Up and to the left oxygen saturation in the placenta is very low compared to maternal blood Fetus has more Hb than adult and fatal Hb has a higher affinity for oxygen

Question 61

How Is fatal blood more adapted to get oxygen

Answer 61

higher affinity for oxygen | More Hb than adult

Question 62

in anaemia what happens to the saturation( PO2 ) and content of the blood

Answer 62

the saturation is not affected so the Hb present will still be effectively saturated content of Hb in blood is halved

Question 63

what does PO2 measure

Answer 63

dissolved oxygen

Question 64

Co2 is 25x more soluble than O2 in plasma - but still needs transport systems Carried in 3 forms

Answer 64

Dissolved in plasma Bicarbonate -generated in RBC Carbamino compounds - generated in RBC as Co2 content increases the PCO2 increases

Question 65

In RBC water and CO2 form bicarbonate and move out the cell to maintain electrochemical balance how do chloride ions move into the cell and HCO3- out

Answer 65

chloride shift buffer effect

Question 66

what is the purpose of the chloride shift

Answer 66

exchange of ions that takes place in RBC in order to ensure that no build up of electric change takes place during gas exchange

Question 67

Co2 can also bind to amino groups to from carbamino compound to take up more Co2 from the tissues what is produced from both this and bicarbonate process that needs to be buffered

Answer 67

protons

Question 68

what is the Haldane effect

Answer 68

the lower the amount of oxyHb the higher capacity of blood to carry Co2

Question 69

In peripheral tissues Hb give up O2 so increases affinity for CO2 increases so has a greater Co2 carriage However in the lungs Hb binds to O2 so affinity for Co2 decreases so allows removal of it from blood as Hb given up CO2 true or false

Answer 69

true

Question 70

frequency of ventilation is controlled by rthymic activity of autonomic neurones in respiratory centre found where

Answer 70

medulla

Question 71

what nerves are involved

Answer 71

phrenic and intercostal nerves

Question 72

central chemoreceptors respond to PCO2and mechanoreceptors in muscles and joints all stimulate respiration in response to exercise. what to peripheral chemoreceptors and baroreceptors do what cranial nerves control motor autonomic function of peripheral chemoreceptors

Answer 72

Baroreceptors stimulate respiration in response to hypotension Peripheral chemoreceptors ( in aortic and carotid bodies) respond to decreased PO2 , metabolic acidosis 9,10

Question 73

CO2 is the main controller of ventilation - how does this work

Answer 73

central chemoreceptors respond to this. The higher the partial pressure of CO2 in blood the more acidic CSF becomes ( BBB) driving up ventilation lowing the partial pressure

Question 74

dependent variable

Answer 74

the effect - the one you are measuring on Y axis

Question 75

independent variable

Answer 75

the one you change

Question 76

Hyperventilation leads to lower levels of CO2 also called ?

Answer 76

Hypocapnia

Question 77

Hypoventilation increases level of Co2 also called what

Answer 77

Hypercapnia

Question 78

pleural reflection

Answer 78

where the pleura changes direction

Question 79

visceral pleura( around lungs) is continuation of parietal pleura true or false

Answer 79

true

Question 80

medial mediastinum contains the heart true or false

Answer 80

true

Question 81

function of intercostal muscles

Answer 81

hold ribs in place and assist In inspiration

Question 82

An 8 year old boy comes into the GP with his mother. His mother explains that he gets SOB quite often and sometimes when he breathes out he makes a strange sound. What is the most likely dx?

Answer 82

asthma obstructive wheeze tests vital-graph and peak flow

Question 83

24. You’re on ward and a really educated patient comes in and tells you that he has an alpha 1 anti trypsin deficiency. What on earth does this mean? 1. He’s got an autoimmune condition 2. Gas exchange can’t take place in the alveoli 3. He has a neurotransmitter problem 4. He is suffering from hyperinflation of the lungs 5. He will have peripheral neuropathy

Answer 83

4 Alpha 1 antitrypsin usually stops elastin in the lungs being broken down by proteases. Therefore a deficiency means elastin is broken down and so lungs can’t inflate and come down and stuff –hyperinflation!