Carriages of gases

Question 1

Where is oxygen in the body found?

Answer 1

1-In alveolar gas in the lungs
2-In solution in the plasma
3-Bound to Haemoglobin (oxyhaemoglobin)
4-Bound to myoglobin in muscle (Oxymyoglobin)

Question 2

Describe the oxygen cascade

Answer 2

the physiological steps that brings atmospheroc oxygen into the body where it is delievered and consumed by metabolically active tissue

Question 3

List the order of partial pressure of O2 in Kpa during the oxygen cascade

Answer 3

highest

-ambient air
-alveolar gas
-areterial blood
-average systemic cappilary blood
-mitochondria

Question 4

What is the equation of oxygen in solution?

Answer 4

Oxygen in solution = partial pressure oxygen x solubility

Question 5

what is the total amount of oxygen in arterial blood?

Answer 5

200ml/litre
only 3ml/litre is in solution

Question 6

What is the oxygen requirement at rest?

Answer 6

• 250ml/min
  -can increase up to 4000ml/min on excersise

Question 7

what is the oxygen requirement in the blood?

Answer 7

-200ml/litre total in bloof
3ml/litre in solution and 197ml/litre bound to Hb
-cardiac output is 5L/min

Question 8

describe the structure of erythrocytes

Answer 8

-biconcave disk-increases SA for O2 uptake
-no nucleum
-7 micrometer diameter
-flexible
each RBC has approx 280 mil Hb

Question 9

what is the structure of adult haemoglobin?

Answer 9

-2 alpha globin chains
-2 beta globin chains

each haem group has an iron atom that can bind to an oxygen molecule

Question 10

What is haemoglobin that releases oxygen known as?

Answer 10

deoxyhaemoglobin (HHb)

Question 11

what is the equation linking Hb02 and HHb?

Answer 11

HHb = O2 -> Hb02 +H+

deoxyhaemoglobin +oxygen -> oxyhaemoglboin + hydrogen ion

Question 12

Describe the association/loading of oxygen and haemoglobin

Answer 12

as O2 binds Hb molecules change shape increasing it affinity for O2

Question 13

What does the oxygen-haemoglobin dissociation curve describe?

Answer 13

the affinity of Hb for O2 at different partial pressures of O2

Question 14

what shape is the oxygen haemoglobin dissociation curve?

Answer 14

sigmoid shape due to cooperative binding

Question 15

When the oxygen haemoglobin dissociation curve shifts right what does it show?

Answer 15

a reduced affinity for haemoglobin for oxygen at a give PO2

Question 16

What are the factors that cause the oxygen haemoglobin dissociation curve to shift right?

Answer 16

-increased temp
-increased PCO2
-Decreased pH (increased acidity)
-increased 2,3- DPG

decreased affinity

Question 17

If haemoglobin is less saturated what happens to the oxygen?

Answer 17

more oxygen is released to the tissues

Question 18

what happens to the blood when there is an increase of CO2?

Answer 18

-increased hydrogen ion conc in the blood- reduced PH

Question 19

Why is there an increased dissociation of oxygen when co2 is increased?

Answer 19

increasing CO2 or reducing the PH weakens the bonds betweeen oxygen and haemoglobin and results in increased dissociation of oxygen to tissue.

Question 20

Describe the Bohr Effect

Answer 20

increased dissociation of oxygen causing a shift in the oxyhaemoglobin disociation curve to the right.

-oxygen will dissociate from haemoglobin at a lower pO2 than normal.

Question 21

what are the three forms of CO2 transport in the blood?

Answer 21

10%- dissolved in plasma as dissolved gas, this determines the PCO2 of the blood

15%-bound to plasma proteins and haemoglobin to for carbamino compouds (carbaminohaemoglobin)

75%- transported as carbonic acid and bicarbonate ions

Question 22

describe the events that occur when CO2 buffers to Bicarbonate ions

Answer 22

-CO2 reactes with H20 to form carbonic acid
-reaction occurs slowly in plasma
-in RBC reaction is catalysed by carbonic anhydrase
-carbonic acid then dissociates to release bocarbonate and hydrogen ions
-Ph is determined by hydrogen ion conc, increased hydrogen ion conc decrases the PH of the blood.

Question 23

Write the symbol equation for CO2 buffering to Bicarbonate ions.

Answer 23

CO2 +H2O <—> H2CO3 <—>HCO3- + H+

Question 24

formula for carbonic acid

Answer 24

H2CO3

Question 25

How are carbamino compounds formed?

Answer 25

-Co2 binds with Amino groups of plasma proteins and haemoglobin
-CO2 combines with haemoglobin to form carboaminohaemoglobin.

Question 26

What is a buffer?

Answer 26

a solution that resists PH changes

Question 27

Define the Haldane effect

Answer 27

binding of oxygen to haemoglobin promoting the release of carbon dioxide and hydrogen ions

o2 and cO2 bind to Hb but at different sites

Question 28

What are the two ways the Haldane effect is achieved?

Answer 28

1-binding of O2 to Hb reduced affinity for CO2 resulting in the dissociation of CO2 in the lungs

2- increased H+ release pushes the reversible equilibrium between bicarbonate and CO2 in the direction of CO2- can be released in the lungs