module 3.2

Question 1

what protein do erythrocytes contain

Answer 1

haemoglobin

Question 2

haemoglobin + oxygen–>

Answer 2

haemoglobin + oxygen–>oxyhaemoglobin

Question 3

what dos each haem group of haemoglobin contain

Answer 3

a single iron ion (Fe2+)

Question 4

what can iron ions do in haemoglobin

Answer 4

attract and hold an oxygen molecule

Question 5

what does affinity mean

Answer 5

attraction

Question 6

what does dissociation mean in terms of haemoglobin

Answer 6

releasing the oxygen from oxyhaemoglobin

Question 7

what is foetal haemoglobin

Answer 7

the type of haemoglobin usually only found in the foetus

Question 8

what does haemoglobin have a HIGH affinity for

Answer 8

oxygen

Question 9

state the process of the transport of oxygen

Answer 9

oxygen is absorbed in the blood as it passes the alveoli in the lungs . o2 molecules diffusing into the blood plasma enter the red blood cells. here they become associated with the haemoglobin (it binds reversibly ). this takes oxygen out of solution so maintains a steep conc gradient, allowing more o2 to enter the blood from the lungs and diffuse into cells.
the blood carries oxygen from the lungs back to the heart, before travelling around the body to supply the tissues. in body tissues, cells need o2 for aerobic respiration. thus haemoglobin must eb able to release oxygen (dissociate)!

Question 10

what does the ability of haemoglobin to associate and release oxygen depend on

Answer 10

the conc of o2 in the surrounding tissues

Question 11

what is the conc of o2 measured by

Answer 11

by the relative pressure that it contributes to a mixture of gasses. this is called the partial pressure of o2 or pO2, its also called the oxygen tension and measured in kPa

Question 12

what sort of curve does the association of oxygen with haemoglobin create and what is this curve called

Answer 12

S-shaped curve- this is called the haemoglobin dissociation curve.

Question 13

describe the haemoglobin dissociation curve and why its shaped like this (bottom of the curve)

Answer 13

at low oxygen tension, the haemoglobin does not readily associate with o2 molecules. This is because haem groups that attract oxygen are in the centre of the haemoglobin molecule. This makes it difficult for the o2 molecule to reach the haem group and associate with it. this difficulty in combining with 1st o2 molecule accounts for the low saturation level of haemoglobin at low o2 tensions.

Question 14

describe the haemoglobin dissociation curve and why its shaped like this (middle of the curve)

Answer 14

as o2 tension rises, diffusion grad into haemoglobin increases. eventually, 1 o2 molecule enters haemoglobin and associates with one of the haem groups causing a conformational change allowing o2 molecules to enter haemoglobin and associate with other haem groups relatively easy.- this accounts for the steepness as the o2 tension rises

Question 15

describe the haemoglobin dissociation curve and why its shaped like this (top of the curve)

Answer 15

as haemoglobin reaches 100% saturation, the curve levels off.

Question 16

talk about the oxygen tension in the lungs and the oxygen tension in the respiring body tissues

Answer 16

o2 tension in the lungs is sufficient to produce close to 100% saturation. The o2 tension in respiring body cells is sufficiently low to cause oxygen to dissociate readily from the oxyhaemoglobin.

Question 17

how is fetal hemoglobin different to adult hemoglobin- talk about curve too

Answer 17

it has a higher affinity for oxygen thus the hemoglobin dissociation curve is to the left of the adult curve.

Question 18

why does fetal hemoglobin have a higher affinity than adult hemoglobin

Answer 18

because fetal hemoglobin must be able to associate with o2 in an environment where o2 tension is low enough to make adult hemoglobin release o2

Question 19

in the placenta, is o2 tension low or high

Answer 19

low

Question 20

what does the fetal hemoglobin do and what dos this do to the o2 tension. what does it do to the mothers blood

Answer 20

in the placenta where o2 tension is low, fetal hemoglobin will absorb o2 from the surrounding fluid, this reduces o2 tension even further, as a result oxygen diffuses from the mothers blood into the placenta- this reduces o2 tension within the mothers blood which makes the maternal hemoglobin release more o2 (dissociation)

Question 21

what are the 3 ways co2 is transported

Answer 21

• dissolved directly in placenta (5%)
  -combined with hemoglobin to form a compound called carbaminhaemoglobin (10%)
  -transported in the form of hydrogen carbonate ions (HCO3-)

Question 22

Describe the formation of hydrogen carbonate ions (4 STEPS) (6)

Answer 22

-co2 in the blood plasma diffuses into red blood cells, here it combines with a weak acid called carbonic acid. this reaction is catalyzed by carbonic anhydrase.
CO2+H20–>H2CO3
-This carbonic acid dissociates to release H+ ions and hydrogen carbonate ions(HCO3-)
-The hydrogen carbonate ions diffuse out of the red blood cells into the plasma. the charge inside the red blood cell is maintained by the movement of cl- ions from the plasma into the red blood cell-this is the chloride shift.
-the hydrogen ions building up in the red blood cell could cause contents of red blood cell to become v acidic. to prevent this, H+ ions are taken out of solution by associating with hemoglobin to produce hemoglobinic acid. the hemoglobin is acting as a buffer

Question 23

whats a buffer

Answer 23

a compound that maintains constant pH

Question 24

whats hemoglobinic acid

Answer 24

the compound formed by the buffering action of hemoglobin as it combines with excess H+ ions

Question 25

in the tissues, the partial pressure of o2 is lower thus oxyhemoglobin begins to dissociate and release o2 to the tissues, what dos this mean that hemoglobin is available to take and what does this mean...

Answer 25

the hemoglobin is available to take up H+ ions forming hemoglobinic acid, where tissues are very active, more co2 is released.

Question 26

what does the bohr effect describe (1)

Answer 26

describes the effect that an increasing conc of co2 has on the haemoglobin

Question 27

4 steps covering the bohr effect...

Answer 27

- co2 enters the red blood cells forming carbonic acid, which dissociates to release H+ ions. - these H+ ions affect the pH of the cytoplasm, making it more acidic. -as with any protein, changes in pH can affect tertiary structure of the hemoglobin and reduces the affinity of the hemoglobin for o2 -the hemoglobin is unable to hold as much o2 and o2 is released from the oxyhaemoglobin to the tissues

Question 28

where tissues are respiring more, there will be more co2- will there be more or less hydrogen ions produced in the red blood cell and what does this make oxyhemoglobin do

Answer 28

more H+ ions produced in the red blood cell making the oxyhemoglobin release more oxygen.

Question 29

overall, what does the bohr effect lead to

Answer 29

results in more o2 being released

Question 30

what happens to the hemoglobin dissociation curve in result to the bohr effect

Answer 30

shifts downwards and to the right

Question 31

what are the two main pumping chambers

Answer 31

the ventricles and the atrium

Question 32

what is situated above the ventricles

Answer 32

the atrium

Question 33

what are the atrio-ventricular valves

Answer 33

valves between the atria and ventricles which ensures that blood flows in the right direction

Question 34

whats cardiac muscle

Answer 34

specialised muscle found in the walls of the heart chambers

Question 35

semilunar valves

Answer 35

valves that prevent blood from re-entering the heart from the arteries

Question 36

what type of blood does the right side pump

Answer 36

deoxygenated blood to the lungs to get oxygenated

Question 37

what type of blood does the left side pump

Answer 37

oxygenated blood to the rest of the body

Question 38

what lie over the surface of the heart and what do they supply

Answer 38

coronary arteries that supply oxygenated blood to the heart muscle.

Question 39

what can restricted blood flow to the heart muscle cause

Answer 39

angina or heart attack.

Question 40

what do the atria receive

Answer 40

blood from major veins

Question 41

what are the two main veins leading into the atrium

Answer 41

the vena cava and the pulmonary vein

Question 42

in the vena cava what is the type of blood and where does it move

Answer 42

deoxygenated blood from the body which moves into the right atrium

Question 43

in the pulmonary vein what is the type of blood and where does it move

Answer 43

oxygenated blood from the lungs which moves into the right atrium

Question 44

what are attached to the valves and what do they do

Answer 44

tendinous chords which prevent the valves from turning inside out when the ventricle walls contract

Question 45

what does the wall of muscle called the septum do

Answer 45

separates the ventricles from each other- ensures that oxygenated blood keeps to the left side and deoxygenated blood sticks to the right side

Question 46

what type of vessel does blood leaving the heart go into

Answer 46

arteries

Question 47

where does deoxygenated blood leave and what does it go into

Answer 47

the right ventricle into the pulmonary artery

Question 48

where does oxygenated blood leave and what does it go into

Answer 48

the left ventricle into the aorta

Question 49

whats the structure and function of the atria

Answer 49

- thin walls - function= receive blood from the veins and push it into the ventricles

Question 50

whats the structure and function of the right ventricle

Answer 50

-thicker than the walls of the atria -pumps deoxygenated blood to the lungs

Question 51

whats the structure and function of the aorta

Answer 51

connected to the left of the ventricle -carries blood away from the heart to the body

Question 52

whats the structure and function of the left ventricle

Answer 52

- 2 or 3 times thicker than the right ventricle as a lot more pressure -the blood from the left ventricle is pumped out the aorta

Question 53

what does the atrioventricular valves prevent

Answer 53

prevent backflow of blood from the arteries

Question 54

what do the pulmonary veins carry

Answer 54

oxygenated blood from the lungs

Question 55

what do the pulmonary arteries carry

Answer 55

deoxygenated blood from the heart

Question 56

describe the cardiac muscle structure

Answer 56

-consists of fibres that branch making cross bridges- these help spread stimulus across the heart and the muscle can produce a squeezing action. -numerous mitochondria between muscle fibres to supply energy for contraction. -muscles are separated by intercalated discs which facilitate synchronised contraction, each cell has a nucleus and is divided into contractile units called sarcomeres