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Biology Unit 2 > Circulatory System > Flashcards

Circulatory System Flashcards

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1
Q

Why do large organisms, like mammals, require a circulatory or transport system?

A

Larger organisms have smaller surface area to volume ratios, so a transport system is needed to supply oxygen and glucose to every metabolically active cell in their large volume

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2
Q
  1. Why does the right ventricle not need to generate much pressure?
A

The pulmonary circuit to the lungs is only a short circuit

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2
Q
  1. Why is the wall of the left ventricle much more muscley?
A

The blood in the systemic circuit must be under large enough pressure to deliver glucose and oxygen quickly to our organs and tissues as well as take wastes away quickly

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2
Q
  1. What does “Double Circulatory System” mean?
A

It means that the blood passes through the heart twice for each complete circuit of the body, once in the pulmonary circuit to the lung and once in the systemic circuit to the rest of the body tissues

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3
Q
  1. What is the advantage of the low pressure in the pulmonary circuit?
A

There is more time for gas exchange between the alveoli and the capillaries of the lungs

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4
Q
  1. What is the advantage to mammals of having a 4 chambered heart and double circulation?
A
  • Oxygenated blood can be delivered quicker and at a greater pressure to all the cells * This allows mammals to be larger and lead active lives with high energy demands
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5
Q
  1. What is the disadvantage of a single circulatory system, as seen in fish?
A

As there is only a single circuit, once blood has passed through the gill capillaries, its pressure is reduced which means less pressure behind the blood flow to other body organs

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6
Q
  1. What is the role of the elastic tissue in the thick walls of arteries?
A

Elastic tissue allows arteries to 1. Stretch/distend to withstand the high pressure and 2. recoil between heart beats to maintain pressure and push blood along

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7
Q
  1. What is the role of smooth muscle in the thick walls of arteries?
A

Smooth muscle 1. controls blood flow to organs via vasoconstriction (narrowing of lumen when smooth muscle contracts) and vasodilation (widening of lumen) 2. Helps to maintain blood pressure via vasoconstriction

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8
Q
  1. What is the role of the inner squamous endothelium layer of both arteries and veins?
A

It provides a smooth surface for reducing friction to blood flow

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9
Q
  1. What is the role of the thin outer fibrous layer of arteries and veins?
A

Protection

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10
Q
  1. What is the significance of having less smooth muscle and elastic tissue, a larger lumen and the presence of valves in veins when compared to arteries
A
  • The blood is under much lower pressure in veins, therefore less elastic tissue and smooth muscle is needed * The large lumen means that there is little resistance to blood flow * The valves prevent backflow of blood
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11
Q
  1. How are capillaries adapted for exchange?
A

Thin permeable walls to reduce diffusion distance * Narrow lumen reduces diffusion distance and allows RBCs to squeeze through slowly * The huge networks of capillaries increase surface area for diffusion

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11
Q
  1. What is the only tissue layer that arteries, veins and capillaries have in common
A

Squamous endothelium

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11
Q
  1. What happens in the capillaries?
A

The exchange of gases, solutes and wastes between the blood and the tissue fluid surrounding cells and tissues

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12
Q
  1. Why does both blood pressure and velocity drop when blood reaches the capillaries?
A

The arterioles branch into millions of capillaries in huge capillary networks (now further away from the heart) which causes a large increase in surface area

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13
Q
  1. How is the heart muscle “myogenic”?
A

Myogenic means that it can generate its own electrical impulses to cause contraction

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14
Q
  1. How is the heart supplied with the oxygen and glucose it needs to maintain its high metabolic rate?
A

The coronary arteries supply the cardiac muscle with oxygen and glucose

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15
Q
  1. How are cardiac muscle cells adapted to their function?
A

They are branched and have bridges to enable conduction of electrical impulses through walls of atria and ventricles

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16
Q
  1. Why are the atria only thin-walled?
A

They need less cardiac muscle as they only receive blood (from the body or the lungs)

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17
Q
  1. Why do the ventricles have thicker walls?
A

They have more cardiac muscle to enable them to generate the pressure needed to pump the blood all around the body (left ventricle) and to the lungs (right ventricle)

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18
Q
  1. What is the job of the atrioventricular or AV valves (tricuspid and bicuspid)?
A

They prevent backflow into the atria when the ventricles contract

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18
Q
  1. What is the job of the semilunar or pocket valves? (pulmonary and aortic)?
A

They prevent backflow from the pulmonary artery and the aorta into the ventricles during diastole

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19
Q
  1. Why do the AV valves have chordae tendinae attaching them onto papillary muscles on the ventricle walls?
A

The chordae tendinae are tough, flexible structures needed to prevent the AV valves from turning inside out during ventricular contraction

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20
Q
  1. The semilunar valves are pocket valves. What does this mean?
A

They close when the pressure in the arteries leaving the heart is greater than in the ventricles but are pushed flat against the artery walls during systole so they don’t impede flow out of the heart

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21
Q
  1. What are the valves made from?
A

Connective tissue

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22
Q
  1. What is the cardiac cycle?
A

The sequence of events that occur during one heart-beat

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23
Q
  1. In the cardiac cycle, what causes the AV valves to open initially?
A

The refilling of the atria during diastole increases the pressure in the atria to above that in the ventricles

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24
Q
  1. What causes the AV valves to then shut?
A

Ventricular systole begins which increases the pressure in the ventricles to above the pressure in the atria

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25
Q
  1. Where does the electrical signal which causes the atria to contract originate?
A

The sino-atrial node or SAN, found in the wall of the right atrium

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25
Q
  1. What causes the semi-lunar valves (pulmonary and aortic) to open?
A

During ventricular systole, when the pressure in the ventricles becomes greater than in the arteries, the semi-lunar valves are forced open

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26
Q
  1. What causes the semi-lunar valves (pulmonary and aortic) to slam shut?
A

The blood has left the ventricles and entered the arteries and ventricle walls relax making the pressure in the arteries greater than the pressure in the ventricles

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27
Q
  1. What causes the 2 heart sounds
A
  1. The AV valves shutting 2. The semi-lunar valves shutting found
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28
Q
  1. Where does the electrical signal that causes the ventricles to contract originate from?
A

The atrio-ventricular node or AVN, found in the right atrium, closer to the AV valves

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29
Q
  1. How does the electrical signal from the AVN reach the ventricular walls?
A

The impulse travels down the septum, in the BUNDLE OF HIS to the apex of the heart and then up the ventricle walls in PURKINJE FIBRES

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30
Q
  1. Why is it important that ventricular systole is initiated from the bottom of the chambers (apex of heart) upwards?
A

This ensures that blood is pumped upwards and into the arteries leaving the heart

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31
Q
  1. What is an electrocardiogram (ECG)?
A

An ECG is a graphical representation of the electrical activity in the heart during the cardiac cycle

32
Q
  1. What is atherosclerosis?
A

Atherosclerosis is the disease caused by thickening of the artery wall which reduces the size of the lumen and increases the blood pressure

33
Q
  1. What is an atheroma?
A

An atheroma is a build-up of fatty deposits that form within an artery wall

34
Q
  1. How do atheromas and hardened plaques affect structure and function of the artery?
A
  1. The atheromas/plaques narrow the lumen, which restricts bloodflow and raises blood pressure 2. The build-up of fibrous material reduces elasticity reducing ability to carry out vasoconstriction and vasodilation
35
Q
  1. How does the atheroma grow and form a hardened plaque?
A

Within the artery wall, macrophages, cholesterol, dead smooth muscle cells, salts and fibrous tissue build up to form a hardened plaque

36
Q
  1. What is a thrombosis?
A

Thrombosis is the formation of blood clots within the blood vessels

37
Q
  1. What is a coronary thrombosis?
A

Coronary thrombosis occurs when the blood clots are found in the coronary arteries

38
Q
  1. What might cause the coronary thrombosis?
A

Damage caused by atherosclerosis and plaques rupturing

39
Q
  1. What is an angiogram?
A

An angiogram is a special x-ray image produced which shows the journey of a contrast dye through the blood vessels

40
Q
  1. What is an angiogram used for?
A

It shows up narrowing or damage to blood vessels

41
Q
  1. How are RBCs adapted for their function of transporting oxygen?
A
  • They contain the pigment haemoglobin for carrying oxygen * They have no nucleus or organelles, to give more room for haemoglobin * Their biconcave shape gives them a large surface area to volume ratio for 02 transport and gas exchange
42
Q
  1. What treatment may be used to treat narrowing of a coronary blood vessel?
A

Angioplasty, which uses a stent to dilate the relevant area

43
Q
  1. What is plasma?
A

The liquid component of blood which transports RBCs, amino acids and glucose, ions, CO2, urea, fibrinogen, prothrombin and clotting factors

44
Q
  1. What do polymorphs do?
A

Carry out phagocytosis: They engulf foreign material eg bacteria, encase it in a phagosome and digest it intracellularly using enzymes

44
Q
  1. Describe polymorphs (microphages)
A

Small white blood cells with * Multi-lobed nucleus * Granular cytoplasm

45
Q
  1. Describe lymphocytes
A

White blood cells with * A large, round nucleus and little cytoplasm

45
Q
  1. Describe monocytes (macrophages)?
A

Larger white blood cells with: * A bean-shaped nucleus NON-GRANULAR cytoplasm

46
Q
  1. What do monocytes do?
A

Carry out Phagocytosis (for example, at the site of a wound)

47
Q
  1. What do lymphocytes do?
A

B- lymphocytes produce antibodies that attack foreign antigens T-lymphocytes attack and kill foreign antigens or infected cells

48
Q
  1. What are platelets?
A

Cell fragments involved in blood clotting and repairing minor damage to blood vessels

49
Q
  1. What is the importance of clotting?
A
  1. It prevents entry of pathogens by sealing wounds 2. It prevents too much loss of essential body fluid/plasma
50
Q
  1. What name is given to the type of reactions involved in blood clotting?
A

A cascade of reactions (meaning that certain compounds catalyse reactions which are on further down the chain)

51
Q
  1. When platelets are activated by damage, what does this cause the release of and what must also be present for the cascade reactions to begin?
A

Clotting factors including tromboplastin are released. Calcium ions and Vitamin K must be present.

52
Q
  1. What are thromboplastin, the clotting factors, calcium ions and vitamin K needed for?
A

Converting prothrombin to thrombin

53
Q
  1. What does thrombin do?
A

Catalyses the conversion of soluble fibrinogen to insoluble fibrin

54
Q
  1. What does fibrin form?
A

The fibrous strands of fibrin form a mesh that traps the RBCs, forming an insoluble clot

55
Q
  1. What is tissue fluid?
A

Tissue fluid is the fluid that surrounds capillaries and the cells of our tissues

56
Q
  1. What is tissue fluid made up of?
A

Plasma minus RBCs and proteins (i.e. it consists of water, ions, amino acids, glucose, cO2, urea)

57
Q
  1. What is the main force driving the formation of tissue fluid?
A

A hydrostatic pressure, Yp, due to the narrowing of blood vessels pushes tissue fluid out through the capillary walls

58
Q
  1. What force draws tissue fluid back into the capillaries?
A

A lower Y or more negative Ys, in other words, an osmotic pressure, due to the presence of plasma proteins draws tissue fluid back into the capillaries

59
Q
  1. Why is tissue fluid formed at the arterial end of the blood capillaries?
A

At the arterial end, the hydrostatic pressure is greater than the osmotic pressure due to the lower Y in the capillaries

60
Q
  1. Why is tissue fluid drawn back in at the venous end of the capillaries?
A

At the venous end, the osmotic pressure due to the lower Y in the capillaries, is greater than the hydrostatic pressure

61
Q
  1. How is haemoglobin (Hb) a quaternary protein?
A

It consists of 4 polypeptide chains, 2 a-chains and 2 b-chains

62
Q
  1. What happens if there is excess tissue fluid?
A

It is drained into the lymphatic system and becomes lymph

63
Q
  1. How is haemoglobin a conjugated protein?
A

At the centre of each polypeptide chain is a non-protein, iron-containing haem group (the prosthetic group)

64
Q
  1. How many 02 molecules can each haemoglobin molecule carry?
A

Each haem group binds to one oxygen molecule, so therefore 4 oxygen molecules can be carried per haemoglobin molecule (one per polypeptide chain)

65
Q
  1. What does haemoglobin (Hb) become when it has oxygen bound to it?
A

Oxyhaemoglobin

66
Q
  1. What is cooperative loading?
A

When one molecule of oxygen binds to a haem group, a conformational change takes place (change in structure and shape) which facilitates the binding of a second oxygen molecule, which again leads to a structural change making it easier for the 3rd one to bind and so on until all 4 are bound

67
Q
  1. What do we mean by the partial pressure of a gas?
A

Partial pressure of a gas is the proportion of the total air pressure that is due to that gas. It is often expressed as kPa

68
Q
  1. What do we mean by “oxygen dissociation curve” for haemoglobin
A

The oxygen dissociation curve is a graph that shows us the % saturation of Hb with oxygen at different partial pressures of oxygen

69
Q
  1. What does the oxygen dissociation curve tell us about what happens in the lungs?
A

In the lungs, where there is a higher partial pressure of oxygen, Hb has a higher affinity for oxygen, meaning it picks it up and becomes fully saturated

70
Q
  1. What is loading tension?
A

The partial pressure at which the haemoglobin is 95% saturated with 02

71
Q
  1. What does the oxygen dissociation curve tell us about what happens in exercising muscles?
A

In exercising muscles, where there is a very low partial pressure of oxygen, Hb has a much lower affinity for oxygen, meaning it releases its oxygen to the tissues and therefore has a low % saturation of oxygen itself

72
Q
  1. What is unloading tension?
A

The partial pressure at which the haemoglobin is 50% saturated with 02

73
Q
  1. What is the Bohr Effect?
A

The BOHR EFFECT describes the shifting of the oxygen dissociation curve to the right in higher carbon dioxide levels/high partial pressures of CO2 (high pCO2).

74
Q
  1. What is the advantage of the Bohr Shift?
A

During strenuous activity, the increased CO2 produced by muscles shifts the oxygen dissociation curve to the right, meaning that Hb releases its oxygen to the muscle cells (which require it to maintain their higher rate of respiration), more readily.

75
Q
  1. What is myoglobin?
A

Myoglobin is a storage pigment for oxygen, found in our “red” or skeletal muscles

76
Q
  1. Describe the structure of myoglobin
A

Myoglobin consists of one polypeptide chain with a haem group in its centre. The haem group carries one oxygen molecule

77
Q
  1. What is the significance of the shape of the myoglobin dissociation curve?
A

Myoglobin only releases its oxygen when oxygen partial pressures are very low, otherwise it remains fully saturated

78
Q
  1. What is the advantage to us of having myoglobin?
A

When our respiring muscles have run out of oxygen, myoglobin releases its oxygen store, enabling muscular contraction to continue aerobically, delaying the onset of anaerobic respiration

79
Q
  1. What happens to the oxygen in the atmosphere at high altitudes?
A

There is less oxygen available (P02 drops) in the atmosphere as height above sea level increases

80
Q
  1. How does the low oxygen availability affect us?
A

When PO2 decreases at high altitudes, it decreases the ability of our haemoglobin to fully saturate. This will cause altitude sickness and lack of energy.

81
Q
  1. How do high altitude dwellers like Llamas cope with the problem of low PO2?
A

High altitude dwellers have specialised haemoglobin which becomes fully saturated at much lower PO2 values. In other words, Hb’s affinity for oxygen increases. This means that their oxygen dissociation curve for haemoglobin would sit to the LEFT of low level dwellers, such as ourselves

82
Q
  1. If someone moves from a low altitude to a high altitude, how do they ACCLIMATISE?
A
  • The number of RBCs increases to increase the capacity for transporting as much of the available oxygen as possible to the cells * Ventilation rate (breathing depth and rate) increases to maximise the amount of oxygen diffusing from the alveoli into the capillaries during gas exchange
83
Q
  1. How have communities who have lived at high altitude for generations evolved?
A

Over many generations a special type of haemoglobin evolves that saturates at a lower P02 level

Biology Unit 2 (5 decks)

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