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Human Biology Unit 2 > KA7 & 8 > Flashcards

KA7 & 8 Flashcards

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1
Q

What is atherosclerosis?

A

Atherosclerosis is the accumulation of fatty material (consisting mainly of cholesterol, fibrous material and calcium) forming an atheroma or plaque beneath the endothelium

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2
Q

What happens as the atheroma grows?

A

The artery thickens and loses its elasticity. The diameter of the lumen becomes reduced and blood flow becomes restricted resulting in increased blood pressure

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3
Q

Explain the formation of a thrombus

A

Atheromas may rupture damaging the endothelium. The damage to the endothelium releases clotting factors that activate a cascade of reactions resulting in the conversion of the enzyme prothrombin to its active form thrombin, causing a blood clot called a thrombus

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4
Q

What is the formation of a thrombus referee to as?

A

Thrombosis

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5
Q

What does thrombin cause molecules of the plasma protein fibrinogen to do?

A

Thrombin causes molecules of the plasma protein fibrinogen to form threads of fibrin. The fibrin threads form a mesh work that clots the blood, seals the wound and provides a scaffold for the formation of scar tissue

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6
Q

What is clotting?

A

Clotting is the mechanism that prevents blood loss from broken blood vessels

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7
Q

Explain clotting

A
  1. Platelets or damaged cells release a group of proteins called clotting factors. These clotting factors are released into the plasma at a wound site.
  2. Clotting factors activity the enzyme thrombin from its inactive form prothrombin.
  3. Thrombin turns the soluble plasma protein fibrinogen into its insoluble fibrous form fibrin.
  4. The fibrin threads form a mesh work that clots the blood by binding platelets and blood cells to form a plug to seal the wound and provide a scaffold for the formation of scar tissue.
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8
Q

What might a thrombosis in a coronary artery lead to?

A

A myocardial infarction, commonly known as a heart attack

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9
Q

What might a thrombosis in an artery in the brain lead to?

A

A stroke

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10
Q

What leads to the death of tissues?

A

Cells are deprived of oxygen

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11
Q

In some cases, a thrombus may break loose to form what?

A

An embolus

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12
Q

What is an embolus?

A

An embolus travels through the blood stream until it blocks a blood vessel

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13
Q

What is a stroke?

A

A stroke means that the blood supply to a part of the brain is suddenly cut of. Soon after the blood supply is cut off, the cells in the affected area of the brain become damaged or die.

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14
Q

What is a heart attack/myocardial infarction?

A

Death of part of the heart muscle following a blockage in its blood supply

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15
Q

What causes peripheral vascular disease?

A

Peripheral vascular disease is caused by narrowing of the arteries due to atherosclerosis other than those of the heart or brain

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16
Q

What is most commonly affected by peripheral vascular disease?

A

The arteries to the legs

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17
Q

What is peripheral vascular disease?

A

Pain is experienced in the leg muscles due to a limited supply of oxygen

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18
Q

What is deep vein thrombosis?

A

A deep vein thrombosis is a blood clot that forms in a deep vein most commonly in the leg.

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19
Q

What may deep vein thrombosis result in?

A

A pulmonary embolism

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20
Q

What is a pulmonary embolism?

A

A pulmonary embolism is caused when an embolus blocks the pulmonary artery. This results in chest pain and breathing difficulties.

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21
Q

What is cholesterol?

A

A fatty substance known as a lipid found in the cell membrane. It is necessary for normal functioning of the body.

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22
Q

What is cholesterol used to make?

A

The sex hormones - testosterone, oestrogen, and progesterone

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23
Q

Where is cholesterol made?

A

Cholesterol is synthesised by all cells, but 25% of total production takes place in the liver

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24
Q

What causes an increase in cholesterol levels in the blood?

A

At diet high in saturated fats or cholesterol

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25
Q

What transports cholesterol?

A

Cholesterol is carried in the blood by proteins

26
Q

What happens when cholesterol and proteins combine?

A

They form lipoproteins

27
Q

What are the 2 main types of lipoproteins?

A

HDL - high density lipoprotein which is the good cholesterol

LDL - the low density lipoprotein which is the bad cholesterol

28
Q

What does HDL transport?

A

Excess cholesterol from the body cells to the liver for elimination which prevents the accumulation of cholesterol in the blood.

29
Q

What does LDL transport?

A

Cholesterol to body cells

30
Q

What may result in the formation of atheromas?

A

Most cells have LDL receptors that take LDL into the cells where it releases cholesterol. Once a cell has sufficient cholesterol, a negative feedback system inhibits the synthesis of new LDL receptors and LDL circulates in the blood where it may deposit cholesterol in the arteries forming atheromas

31
Q

What will result in lower cholesterol and reduced chance or atherosclerosis?

A

A higher ratio of HDL to LDL

32
Q

What tends to raise HDL levels?

A

Regular physical activity

33
Q

What do dietary changes tend to do?

A

Reduce total levels of fat in the diet and to replace saturated with unsaturated fats

34
Q

How do drugs such as statins reduce blood cholesterol?

A

By inhibiting the synthesis of cholesterol by liver cells

35
Q

What are blood glucose levels measured in?

A

millimoles per litre

36
Q

What is chronic elevated blood glucose levels?

A

Chronic elevated blood glucose levels causes the endothelium cells lining the blood vessels to take in more glucose than normal.

37
Q

What are the 2 ways that chronic elevated blood glucose levels can damage the blood vessels?

A

Macro vascular disease

Micro vascular disease

38
Q

What is macro vascular disease?

A

Macro vascular disease refers to damage to larger blood vessels. In larger blood vessels, elevated blood glucose levels may cause atherosclerosis which can lead to cardiovascular disease (including heart attacks and stroke) and peripheral vascular disease (reduced blood flow to limbs)

39
Q

What is micro vascular disease?

A

Micro vascular disease refers to damage to small blood vessels. In smaller blood vessels, elevated blood glucose levels may lead to haemorrhage of blood vessels in the retina, renal failure, and peripheral nerve dysfunction(numbness and slow down or stop the healing of injuries in the hands and feet)

40
Q

We need our blood sugar levels to remain constant. This is achieved using negative feedback control which involves what hormones?

A

Insulin

Glucagon

41
Q

Explain what happens when there is an increase in blood glucose

A

An increase is blood glucose levels is detected by the pancreatic receptors.

The pancreas respond by increasing the secretion of insulin.

Insulin activates the conversion of glucose to glycogen in the liver decreasing blood glucose concentration.

42
Q

Explain what happens when there is a decrease in blood glucose

A

A decrease in blood glucose levels is detected by the pancreatic receptors.

The pancreas responds by increasing secretion of glucagon.

Glucagon activates the conversion of glycogen to glucose in the liver increasing blood glucose concentration.

43
Q

What is adrenaline?

A

Adrenaline is released from the adrenal glands which are located above the kidneys

44
Q

What does adrenaline do?

A

Adrenaline stimulates glucagon secretion and inhibits insulin secretion. This stimulates the liver to breakdown glycogen into glucose and release the glucose into the bloodstream.

45
Q

What are glucose concentrations raised by?

A

During exercise and fight or flight responses, glucose concentrations in the blood are raised by the hormone adrenaline

46
Q

What is diabetes?

A

Diabetes is failure to control blood glucose levels and an impaired ability to restore glucose

47
Q

When does type 1 diabetes usually occur?

A

In childhood

48
Q

What is type 1 diabetes?

A

A person with type 1 diabetes is unable to produce insulin and can be treated with regular doses of insulin

49
Q

When does type 2 diabetes typically occur?

A

Typically develops in later life

50
Q

What is type 2 diabetes?

A

In type 2 diabetes, individuals produce insulin but their cells are less sensitive to it. The insulin resistance is linked to a decrease in the number of insulin receptors in the liver, leading to a failure to convert glucose to glycogen.

51
Q

Why is testing urine for glucose used as an indicator of diabetes?

A

In both types of diabetes, an individuals blood glucose concentrations will rise rapidly after a meal. The kidneys will remove some of this glucose, resulting in glucose appearing in urine

52
Q

When is a glucose tolerance test used to diagnose diabetes?

A

If your urine tests positive for glucose then a glucose tolerance test is used to diagnose diabetes

53
Q

When are blood glucose concentration of the individual measured?

A

After fasting

54
Q

What effect does the glucose solution have on the blood glucose concentration of a diabetic person?

A

During the test a diabetics blood glucose concentration increases to a much higher level than that of a non diabetic and takes much longer to return to its starting concentration

55
Q

What is obesity a major risk factor for?

A

Cardiovascular disease and type 2 diabetes

56
Q

What is obesity characterised by?

A

Excess body fat in relation to lean body tissue such as muscle

57
Q

What is obesity linked to?

A

High fat diets and a decrease in physical activity

58
Q

What is body mass index(BMI)

A

BMI is commonly used to measure obesity but can wrongly classify muscular individuals as obese

59
Q

What is the formula for calculating BMI?

A

BMI=body mass(kg) / height(2) in metres

60
Q

What BMI indicates obesity?

A

A BMI greater than 30

61
Q

How is obesity reduced?

A

Exercise increases energy expenditure and preserves lean tissue. Excersise can help to reduce risk factors of CVD.

62
Q

How can exercise help reduce CVD risk factors?

A

Keeping weight under control
Minimising stress
Reducing hypertension
Improving blood lipid profiles

Human Biology Unit 2 (7 decks)

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