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BIOLOGY A LEVEL > TOPIC 3 - A: exchange and transport systems 2 > Flashcards

TOPIC 3 - A: exchange and transport systems 2 Flashcards

(70 cards)

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1
Q

What is a hydrolysis reaction?

A

A reaction that breaks bonds through the addition of water

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2
Q

What type of enzymes are needed to break down lipids?

A

Lipases

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3
Q

Describe how micelles are formed in digestion

A

Once lipids have been broken down by lipase, the monoglycerides and fatty acids stick with the bile salts to form micelles

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4
Q

Describe the action of endopeptidases

A

Hydrolyse peptide bonds within a protein e.g trypsin which is synthesised in the pancreas and secreted in the small intestine

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5
Q

Describe the action of exopeptidases

A

Hydrolyse peptide bonds at the ends of protein molecules - they remove single amino acids from proteins e.g dipeptidases which work specifically on dipeptides to separate the 2 amino acids

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6
Q

Explain how monoglycerides and fatty acids are absorbed across the ileum epithelium

A

The micelles break up, releasing the monoglycerides and fatty acids, which diffuse directly across the membrane because they’re lipid soluble

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7
Q

How are sodium ions involved in the transport of amino acids?

A

Sodium ions are actively transported out of the ileum epithelial cells into the blood. This creates a sodium ion concentration gradient. Sodium ions then diffuse from the lumen of the ileum into the epithelial cells through sodium-dependant transporter proteins, carrying the amino acids with them.

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8
Q

Role of bile salts in the digestion of lipids

A

Bile salts are produced by the liver and emulsify lipids - this means they cause the lipids to form small droplets, giving them a larger surface area for lipases to work

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9
Q

Where is haemoglobin found in humans?

A

Red blood cells

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10
Q

What is the role of haemoglobin?

A

To carry oxygen around the body

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11
Q

How many polypeptide chains does a haemoglobin molecule have?

A

4

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12
Q

Describe what is meant by haemoglobin ‘loading’ and ‘unloading’ oxygen

A

Loading describes oxygen binding with haemoglobin and unloading describes oxygen being released from haemoglobin

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13
Q

What is formed when oxygen is loaded onto haemoglobin?

A

Oxyhaemoglobin

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14
Q

What is shown on an oxygen dissociation curve?

A

How saturated haemoglobin is with oxygen at any given partial pressure of oxygen

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15
Q

Why does the binding of a single oxygen molecule increase haemoglobin’s affinity for oxygen?

A

It changes the shape of haemoglobin in a way that makes it easier for other oxygen molecules to join too

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16
Q

Where in the body would you find cells with high PO2?

A

In the alveoli/ lungs. This is the site where oxygen first enters the blood so it has the highest concentration of oxygen

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17
Q

Why do mammals need a circulatory system?

A

Mammals have low SA:V ratio so they need a specialised mass transport system to carry raw materials from specialised exchange organs to their body cells

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18
Q

Name the two blood vessels that carry blood into the heart

A

Pulmonary vein and vena cava

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19
Q

Which blood vessel carries deoxygenated blood to lungs?

A

Pulmonary artery

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20
Q

Which blood vessel carries blood to the kidneys?

A

Renal artery

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21
Q

Which vessels supply the heart tissue with blood?

A

Coronary arteries

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22
Q

Describe the structure of an artery

A

Thick muscular wall with elastic tissue and a folded endothelium

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23
Q

What is an arteriole?

A

A blood vessel that branches off from an artery

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24
Q

Why do veins have valves?

A

To prevent back flow of blood

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25
Give two ways in which capillaries are adapted for efficient diffusion
The walls are one cell thick, always very near cells in exchange tissues
26
What is tissue fluid?
Fluid that surrounds cells in tissues
27
Explain the movement of fluid at the arteriole end of a capillary bed
The hydrostatic pressure inside the capillaries is higher than in the tissue fluid. This means fluid is forced out of the capillaries and into the space around the cells, forming tissue fluid
28
Explain the movement of water at the venule end of the capillary bed
The water potential is lower in capillary than in the tissue fluid. This means some water re-enters the capillaries from the tissue fluid by osmosis
29
Which side of the heart pumps deoxygenated blood?
Right side
30
Why does the left ventricle of the heart have a thicker, more muscular wall than the right ventricle?
So that it can contract more powerfully, which means the blood can be pumped further and so travel all round the body. The less muscular right ventricle cannot contract as powerfully so cannot pump blood as far
31
Name the valves that link the ventricles to the aorta and pulmonary artery - what is their function?
Semi-lunar valves - they stop blood flowing back into the heart after the ventricles contract
32
What is the cardiac cycle?
An ongoing sequence of contraction and relaxation of the atria and ventricles that keeps blood continuously circulating around the body
33
When the atria contract, describe the pressure and volume changes that take place in the atria
The volume of the atria decreases and the pressure increases
34
What is an atheroma?
Fibrous plaque formed from the build up and hardening of white blood cells, lipids and connective tissue
35
What is an aneurysm
Ballon-like swelling of an artery. It starts with the formation of an atheroma - atheroma plaques damage, weaken and narrow arteries thus increasing blood pressure. When blood travels through it may push the inner layers of the artery through the outer elastic layer to form an aneurysm
36
What is thrombosis?
Formation of a blood clot - starts with the formation of an atheroma. Atheroma plaque can rupture the endothelium of an artery which damages it leaving a rough surface. Platelets and fibrin accumulate at the site of damage and form a blood clot.
37
What is myocardial infarction?
If coronary artery becomes completely blocked an area of the heart muscle receives no oxygen which causes a heart attack. This causes damage and death of the heart muscle.
38
Give 2 effects an atheroma has on the artery it's in
An atheroma partially blocks the lumen of an artery and restricts blood flow
39
Explain how high blood pressure leads to an increased risk of cardiovascular disease
High blood pressure increases the risk of damage to the artery walls. Damaged walls have an increased risk of atheroma formation
40
Give 3 things that could cause an increase of blood pressure
Atheroma formation, being overweight, not exercising, excessive alcohol and high salt diet
41
Give 2 examples of risk factors for cardiovascular disease that can be controlled
Diet high in saturated fat or salt and smoking
42
Give an example of risk factor for cardiovascular disease that can't be controlled
High blood pressure as a result of another condition or genetic predisposition
43
Explain how highest pressure is produced in the left ventricle
Contractions are stronger due to thicker muscle wall
44
How does a whole between ventricles affect someone
Oxygenated and deoxygenated blood are combined so a lower volume of oxygenated blood leaves the heart
45
Explain why semilunar valves open
The pressure behind them in the ventricles is higher than in the vessels
46
Explain the importance of a short delay of the atrioventricular valve
The delay gives time for the chambers to fill with blood before contraction of ventricles
47
What is a stroke volume?
Volume of blood pumped out the ventricles every beat of the heart
48
Why is the resting heart rate of an athlete lower?
Increased size of the heart, increased heart muscle so stronger contractions, increased stroke volume
49
What is the inner lining of an artery
Endothelium
50
What is the importance of elastic fibres in the wall of the aorta?
Allows the vessel to recoil when the heart beats in order to maintain a constant pressure
51
Explain the importance of muscle fibres in the wall of the arteriole
Muscle fibres allows the lumen to narrow as the muscle contracts
52
Why does the rate of blood flow decrease from the aorta to the capillaries?
The total cross sectional area is higher in the capillaries
53
What are the advantages of capillaries being narrow?
Slows blood flow, short diffusion pathway, fast exchange
54
What factor limits the internal diameter of the lumen of a capillary?
Width of the red blood cell
55
Why is the volume of blood leaving the capillary network into the veins less than the volume of blood entering the arteries?
Fluid in tissue fluid
56
Explain why a lack of protein in the blood causes a build up of tissue fluid
Water potential of the capillary is higher than usual, so less water is exchanged into the capillary by osmosis
57
How does smooth muscle affect blood flow?
Muscle can contract, narrowing the lumen of the vessel
58
Why does the hydrostatic pressure decrease from the arteriole end of the capillary to the venue end of the capillary?
Loss of water
59
How does high blood pressure lead to an accumulation of tissue fluid?
Blood is at higher pressure in the capillary resulting in higher hydrostatic pressure which increases outwards pressure from arteriole end of the capillary so more tissue fluid forms.
60
Why is the water potential of the blood plasma more negative at the venue end of the capillary than the arteriole end?
Water has left the capillary and proteins in the blood are too large to leave the capillary which increases the concentration of blood proteins
61
What is partial pressure?
Measure of concentration of a gas
62
What is the advantage of the oxygen dissociation curve shifting to the right?
Haemoglobin has a lower affinity for oxygen so more oxygen can be used in respiration - happens during exercise
63
Give 2 ways in which the total oxygen supplied to muscles during exercise is increased
- Increased pulmonary ventilation - Increased stroke volume
64
How does haemoglobin load and unload in the body
Loading happens at high PO2 in the lungs where haemoglobin has a high affinity for oxygen. Unloading releases oxygen at a low PO2 and is linked to a high CO2 concentration where haemoglobin has a low affinity for oxygen
65
What is the relationship between the SA:V ratio of mammals and the oxygen dissociation curve of their haemoglobin
Smaller mammals have a greater SA:V ratio so more heat is lost as they have a greater rate of metabolism. Oxygen is required for respiration so haemoglobin releases more oxygen (haemoglobin has a low affinity for oxygen). Therefore smaller mammals have an oxygen dissociation curve further to the right
66
Explain why oxygen dissociation curve of a foetus is shifted to the left
Haemoglobin has a higher affinity for oxygen so loads more oxygen. Therefore oxygen moves from mother to foetus
67
What is the advantage of foetal haemoglobin being replaced with adult haemoglobin after birth?
Haemoglobin has a low affinity for oxygen so unloads oxygen for respiring tissues
68
Explain how aerobic respiration in cells leads to a change in the pH of blood plasma
CO2 produced in respiration is acidic, thus decreasing the pH of blood plasma
69
What is the advantage to tissue cells of a reduction in the affinity of haemoglobin for oxygen when the plasma pH decreases?
Oxygen unloads from oxyhaemoglobin more readily to be used in respiration as cells need more O2
70
Why is it beneficial for mice living at high altitudes to have a dissociation curve shifted to the left? Why is it a disadvantage to be too far to the left?
High altitudes have a low PO2 so a high affinity of haemoglobin with O2 therefore sufficient oxygen is provided to cells. Too far to the left makes it difficult to offload oxygen from oxyhaemoglobin

BIOLOGY A LEVEL (7 decks)

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