7.Mass Transport

Question 1

What is the structure of haemoglobin

Answer 1

Primary-sequence of amino acids in the four polypeptides
Second-each polypeptide coiled into a helix
Tertiary-each polypeptide folded into precise shape -important
Quarte-all 4 linked together to form spherical molecule, each polypeptide associated with haem group contains a ferrous ion

Question 2

What does the ferrous ion in the haem group do

Answer 2

Each one can combine with single oxygen molecule, so 4 oxygen molecules carried by one haemoglobin molecule in humans

Question 3

What is unloading and loading oxygen

Answer 3

Process by which haemoglobin binds with oxygen is loading or associating.

Process by which haemoglobin releases its oxygen is unloading or dissociating

Haemolglon with a high affinity for oxygen, take up more easily but release less easily and haemoglobin with low affinity for oxygen, take up oxygen ,es easily but release more easily

Question 4

To be efficient at transporting oxygen haemglobin must:

Answer 4

Readily associate with oxygen at surface of gas exchange

Readily dissociate from oxygen at tissues requiring it

Question 5

How does haemoglobin achieve both properties

Answer 5

• changes affinity under different conditions
• shape changes in presence of certain substances eg carbon dioxide
• new shape haemoglobin molecule binds more loosely to oxygen as result it releases it oxygen

Question 6

What’s the oxygen dissociation curve

Answer 6

Graph showing the relationship between the saturation of haemoglobin with oxygen and the partial pressure of oxygen

Question 7

How to understand different oxygen dissociation curves on the graph

Answer 7

Further to the left-greater the affinity of haemoglobin (loads readily but unloads less easily)

Further to right-lower affinity of haemoglobin (loads less readily )

Question 8

Explanation of the oxygen dissociation curve

Answer 8

1-shape of haemoglobin means hard for first oxygen to bind, low oxygen conc little oxygen binds, gradient of curve is shallow
2-binding of first oxygen changes shape of haemoglobin, easier for next two oxygen molecules to bind to other subunits
3-therefore smaller increase in partial pressure needed to bind second oxygen than first one, positive cooperativity gradient steepens
4-after binding of 3rd harder to bind fourth as probability of finding empty subunit is less likely, gradient levels off

Question 9

What’s the Bohr effect

Answer 9

The greater the conc of carbon dioxide the more readily haemoglobin releases its oxygen.

Question 10

Why does the conc of carbon dioxide change shape of haemoglobin

Answer 10

Dissolved carbon dioxide is acidic and the low pH causes haemoglobin to change shape

Question 11

What are features of transport systems

Answer 11

• suitable medium for carrying materials, liquid base on water as dissolves substances and can be breathed as gas
• form of mass transport, moved around in bulk more rapid than diffusion
• closed system of tubular vessels, branching network throughout organism
• mechanism for moving transport medium, requires pressure difference between one part and another

Question 12

How is mechanism of mass transport achieved

Answer 12

1-use muscular contraction of body muscle or of a specialised pumping organ eg heart

2-rely on natural passive processes eg evaporation of water

Question 13

What is a double closed circulatory system

Answer 13

Blood is confined to vessels and passes twice through the heart in each complete circuit of the body

Because when passed through lungs pressure reduced

Question 14

What are the two sections of the heart and the differences between them

Answer 14

Atrium - thin walled and elastic and stretches as collect blood

Ventricle - thicker muscular wall as it has to contract strongly to pump blood some distance

Question 15

Where does blood from left and right ventricle go to?

Answer 15

Left- goes to body

Right - goes to lungs (thinner muscular wall)

Question 16

Where are the bicuspid valves

Answer 16

Between atrium and ventricles

Called atrioventricular valves

Question 17

Where does the aorta connect to

Answer 17

Left ventricle and carries oxygenated blood around body

Question 18

Where is ve a cava connected to

Answer 18

Right atrium and brings in deoxygenated blood from tissues

Question 19

Where is pulmonary artery connected to

Answer 19

Right ventricle and carries deoxygenated blood to lungs

Question 20

Where is pulmonary vein connected too

Answer 20

Left atrium and brings oxygenated blood back from lungs

Question 21

What are coronary arteries

Answer 21

Blood vessels that supply the heart
Branches off aorta

Blockage of these can cause myocardial infarction (heart attack)

Question 22

What is diastole

Answer 22

Relaxation of the heart

Question 23

What happens during diastole

Answer 23

• Blood return to atria via vena cava and pulmonary vein
• Atria fill-pressure increases
• once pressures exceeds that of ventricles atrioventricular valves open
• aided by gravity
• muscles of walls relaxed, ventricle walls recoil which reduces pressure
• pressure in ventricle lower than in aorta and pulmonary artery, semi lunar valves shut
• dub sound

Question 24

What’s atrial systole

Answer 24

Contraction of atria

Question 25

What happens in atria systole

Answer 25

Contraction of aria walls along with recoil of ventricles fro es remaining blood in atria into ventricles, ventricle walls still relaxed

Question 26

What is ventricle systole

Answer 26

Contraction of ventricles

Question 27

What happens during ventricle systole

Answer 27

Short delay after atria contraction
Allows ventricles to fill, then walls contract simultaneously
Increase blood pressure, forces shut A.V valves prevents backflow
Lub is sound of av shutting
Increased pressure
Pressure exceeds that of aorta and pulmonary artery
Blood forced into them

Question 28

What’s the function of valves

Atrioventricular
Semi lunar
Pocket valves

Answer 28

All prevent backflow and ensure blood moves “forward”

Question 29

What’s the equation for cardiac output

Answer 29

Heart rate x stroke volume

Question 30

What are arteries

Answer 30

Carry blood away from heart and into arterioles

Question 31

What are arterioles

Answer 31

Smaller arteries that control blood flow from arteries to capillaries

Question 32

What are capillaries

Answer 32

Tiny vessels linking arterioles to veins

Question 33

What are veins

Answer 33

Vessels carry blood from capillaries back to heart

Question 34

What basic structures do arteries arterioles and veins have in common

Answer 34

Tough fibrous outer layer
Muscles layer 
Elastic layer
Thin inner lining (endothelium)
Lumen

Question 35

Artery structure related to function

Answer 35

• Thick muscle layer-can be constricted and dilated control volume of water through
• thick elastic-maintain high blood pressure, stretches and recoils, pressure surges
• great thickness of wall-resists vessel bursting under pressure
• no valves-constant pressure due to heart pumping

Question 36

Arterioles structure related to function

Answer 36

Muscle layer thicker than arteries-restrict lumen, resist blood flow controls movement into capillaries
Elastic layer thinner than arteries-blood pressure is lower

Question 37

Vein structure related to function

Answer 37

Muscle layer thin-blood away from tissue so can’t control flow of blood to tissue
Elastic layer thin- too low blood pressure to cause recoil action
Overall thickness is small-pressure within is so low no risk of bursting
Valves through out-no backflow as low pressure, ensures when muscles contract blood flow in one direction

Question 38

Capillary structure related to function

Answer 38

Walls mainly lining layer-extremely thin, rapid diffusion
Numerous and highly branched-large surface area for exchange
Narrow lumen-red blood cells squeezed against side of capillary
Spaces between endothelial cells-allow white blood cells to escape and dal with with infections in tissues

Question 39

What is tissue fluid made of

Answer 39

Water liquid
Contain glucose amino acids fatty acids oxygen and ions in solution
The means by which materials exchanged between blood and cells
Immediate environment of cells
Formed from blood plasma

Question 40

How is tissue fluid formed

Answer 40

• Pumping of heart creates hydrostatic pressure at arteirole end
• Hydrostatic pressure causes tissue fluid to move out of blood -plasma
• pressure is enough to force small molecules out of cappliaries, ultrafiltration

-opposing outward pressure is:Hydrostatic pressure of tissue fluid in capillaries resist outward movement and lower water potential of blood due to blood plasma proteins causes water to move back into blood in cappliaries

Question 41

How does tissue fluid return to circulatory system

Answer 41

• loss of fluid from cappliaries reduces hydrostatic pressure
• when blood reaches venous end hydrostatic pressure considerably lower than that of tissue fluid
• tissue fluid forced back into capillaries
• plasma lost water and stilll contain proteins, lower W.P than tissue fluid
• water leaves tissues via osmosis down w.p gradient
• not all returns to capillaries, remainder carried in lymphatic system

Question 42

What’s the lymphatic system

Answer 42

System of vessels that begin in tissues
Resemble capillaries except have dead ends. Gradually merge into larger vessels that from networks throughout body, larger vessels drain contents back into bloodstream via two ducts that join veins close to heart

Question 43

How are the contents of lymphatic system moved?

Answer 43

Hydrostatic pressure of tissue fluid that left capillaries

Contraction of body muscles that squeeze lymph vessels-have valves to maintain one directional flow

Question 44

Give two reasons why phoneyer does not truly measure rate of transpiration

Answer 44

You assume that all water is lost by evaporation but some molecules will be used in photosynthesis or to make plant turgid