WEEK 8

Question 1

what does V stand for

Answer 1

alveolar ventilation/ pulmonary ventilation/ pulmonary minute ventilation (V)

Question 2

what does Ve stand for

Answer 2

frequency x tidal volume

Question 3

describe the law of diffusion

Answer 3

the rate of gas transfer (ventilation gas) is proportional to 1) tissue areas, 2) diffusion co efficient of gas, 3) difference in partial pressure of the gas on the two sides of the tissue and 4) inversely proportional to the thickness.

Question 4

what is the equation fir ventilation gas

Answer 4

tissue area divided by tissue thickness x diffusion coefficient of gas x ( difference in partial pressure P1-P2)

Question 5

describe partial pressure in gaseous exchange

Answer 5

a diffusive drive eg net diffusion is high to low

Question 6

what is the equation of Pair (mmHg)

Answer 6

PO2 + PCO2 +PN2

Question 7

describe the oxygen haemoglobin dissociation curve (x8)

Answer 7

• according to the graph, the oxygen carried in the blood in combination with haemoglobin mainly on partial pressure.
• normal arterial pressure of oxygen= 95mmHg.
• sigmoidal shape
• % of Hb saturated increases up to Po2 = 40mmHg
• 40+mmHg is slower to rise
• plataeus at 90 to 100mmHg
• at rest only 25% unloaded, 75% remains loaded
• where it is 0 to 0 on the graph= intense exercise

Question 8

what is the oxygen haemoglobin In males and females equation

Answer 8

males= 15 grams Hb/dL blood x 1.34mlo2/hgHb= 20ml o2/dL blood

females= 13 grams Hb/dL x 1.34ml o2/Hb= 17ml

Question 9

describe the relationship between oxygen uptake and gas tension during exercise ( arterial blood, venous blood and alveolar air).

Answer 9

• oxygen and carbon dioxide partial pressure in the alveolar air (PA), arterial blood (Pa) and mixed venous blood (Pv) during rest and graded exercise.
• as relative effort increases the partial pressure of oxygen in arterial blood remains constant or falls onto slightly
• due to the shape if the oxyhemoglobin dissociation curve, arterial oxygen content remains close to resting levels of approx 95-98% saturation

Question 10

describe the oxyhemoglobin curve (x3)

Answer 10

• flat top portion permits arterial PO2 to fluctuate between 90 to 100mmHg without big changes in %Hbo2
• flat top protects %Hb02 against decreases in PO2 in altitude, pollution and with aging/ disease
• at 0 to 40mmHg steep shape allows small changes in PO2 to unload large amounts of O2 from haemoglobin thus increasing oxygen availability for metabolism

Question 11

describe oxygen transport In the muscle (x4)

Answer 11

• myoglobin= Mb
• shuttles oxygen from the cell membrane to the mitochondria
• Mb has a higher affinity for oxygen than haemoglobin
• oxygen reserve for a muscle

Question 12

describe what happens in the majority of carbon dioxide in the tissues

Answer 12

1) CO2 + H2O > H2CO3 > H + + HCO3

2) carbon dioxide is converted to carbonic acid

3) carbonic acid dissociates into bicarbonate

4) at the lungs, the REVERSE happens.

Question 13

describe carbon dioxide exhalation (x3)

Answer 13

• this graph is the effect of oxygenated haemoglobin on carbon dioxide transport in the blood
• as blood moves from tissues ( where carbon dioxide is relatively high and oxygen is low ) to the lungs ( where oxygen is high and carbon dioxide is low) he carbon dioxide dissociation curve in effects shifts from A to B.
• this Haldane effect causes carbon dioxide to be unloaded at the lungs

Question 14

what are the 5 factors respiration also depends on

Answer 14

1) ventilation - air flow to blood flow

2) adequate blood flow required for alveoli to be ventilated

3) inadequate blood flow required for alveoli to be ventilated

4) inadequate perfusion can result from haemorrhage or blockage pulmonary circulation

5) inadequate ventilation= asthma

Question 15

describe the VE/Q ratio (x2)

Answer 15

• more ventilation than blood flow at apex= poor gas exchange
• ve/q <1 = greater blood flow than ventilation

Question 16

what are the two types of pulmonary ventilation

Answer 16

1) neural= central nervous system respiratory control centre

2) humoral= blood borne chemical factors

Question 17

describe the control of pulmonary ventilation ( x6) including “at rest, sub max ex and max ex”

Answer 17

1) during light to moderate exercise ventilation increases linearly with oxygen consumption and co2 production

2) average of 20-25 litres of every oxygen consumed

3) ventilation increases mainly from increases in tidal volume

4) at rest= humeral factors exert greater control of PCO2, temp

5) sub max ex= neural mechanism from higher brain centres exert greatest control

6) max ex= humoral factors may exert greatest effect on hypernea

Question 18

describe central chemoreceptors ( x2)

Answer 18

1- located in the medulla

2) affected by changes in the cerebrospinal fluid concentrations of PCO2 and H+

Question 19

describe peripheral chemoreceptors ( x2)

Answer 19

• respond to increases in co2 and h +
• decreases in po2= disease or altitude

Question 20

what are the PCO2 effects on ventilation (x4)

Answer 20

• 1mmHg= 2 litres per min increase in ventilation
• crated and central chemoreceptors
• changes in arterial PO2 at sea level generally has no effect \
• high altitude

Question 21

what are the 4 neural inputs to the respiratory centre

Answer 21

• motor cortex
• muscle spindles
• muscle chemoreceptors
• right ventricle + lung stretch receptor