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Flashcards in Blood Pressure and Hypertension Deck (68):
1

What is blood flow

The movement of blood through the vessels from the arteries to the capillaries and then into the veins

2

How does velocity of blood flow vary

It varies inversely with the (total) cross sectional area of the vessel through which it is flowing. As the total cross-sectional area of the vessel increases, the velocity of flow increases

3

Where is blood flow slowest and why

It is slowest in the capillaries to allow time for exchange of nutrients and gases

4

What is vascular resistance

The resistance offered by blood vessels to the flow of blood. Resistance occurs where the blood vessels away from the heart oppose the flow of blood

5

Which 3 factors accumulate resulting in resistance

Vessel radius, blood viscosity and blood vessel length

6

What is blood pressure a measure of

The force that blood exerts against the vessel walls as it moves the blood through the vessels

7

What does vascular tone mean

Smooth muscle walls have a degree of resting tension

8

What is arterial blood pressure determined by

Total peripheral resistance and cardiac output

9

What does cardiac output equal

CO = SV x HR

10

What is a sphygomomanometer and how does it work

It is a device used to measure blood pressure. It is composed of an inflatable cuff to restrict blood flow and a mercury/ mechanical manometer to measure the pressure

11

Where is blood pressure measured

In the brachial artery

12

What is normal arterial blood pressure in a healthy adult

120/80

13

How is blood pressure written

Systolic pressure over diastolic pressure

14

What is systolic BP

Systole occurs during the contraction and emptying of the heart

15

What is diastolic BP

Diastole occurs during the relaxation and filling of the heart

16

What is the difference in systolic and diastolic BP called

Pulse pressure

17

What happens to normal arterial blood pressure

It falls at night due to patterns in the circadian rhythm

18

What happens to normal arterial blood pressure with age

Systolic BP increases due to a reduction in the elasticity of the arteries

19

What happens to normal arterial blood pressure during pain, fear, anger and sexual arousal

Short term increases in arterial BP

20

What happens to normal arterial blood pressure when you stand up

BP in all vessels below the heart is increased and BP in all above the heart is reduced

21

What is transient postural hypotension

When you change from lying position to standing about 700ml of blood is lost from the thorax resutling in a decreasing in systolic and diastolic pressures

22

What happens during vasoconstriction

Vascular resistance increases

23

What happens during vasodilation

Vascular resistance decreases

24

What is intrinsic control of blood pressure

Autoregulation which is stretch, temperature and locally released factors

25

What is extrinsic control of BP

autonomic nervous system or hormones

26

Which receptors detect pressure during circulatin

Baroreceptors

27

Where are baroreceptors located

In the walls of the aorta (aortic arch) and carotid arteries (carotid sinus)

28

What happens when increased BP is detected

Increased BP detected by the baroreceptors info relayed cardiovascular control centre. Results in increased parasympathetic input and decreased sympathetic output which leads to decreased cardiac output. Decreased sympathetic input also leads to decreased peripheral resistance

29

Where is the cardiovascular control

Located within the medulla oblongata

30

What do sympathetic cardiac nerves do

Stimulates cardiac output by increasing heart rate and contractility (and so BP)

31

What do parasympathetic cardiac nerves do

Inhibits cardiac output by decreasing HR

32

What does the vasomotor centre regulate

Blood vessel diameter

33

What do vasomotor nerves innervate

Smooth muscles in the arterioles throughout the body to maintain vasomotor tone

34

What does hormonal control of blood pressure involve

The long term control of blood pressure involves the control of blood volume/ sodium balance by the kidneys

35

What 5 hormones are involved in the hormonal control of BP

1. Adrenaline 2. Angiotensin 3. Aldosterone 4. Antidiuretic hormone (ADH) 5. Atrial natriuretic peptide/ hormone

36

What does the renin-angiotensin-aldosterone system regulate

Blood volume

37

What does the renin-angiotensin-aldosterone system do in response to falling BP

Juxtaglomerular cells in kidneys secrete renin into blood. Renin converts angiotension to angiotensin I which is in turn converted to angiotensin II by enzymes from the lungs. Angiotensin II activates 2 mechanisms that raise BP

38

What are the two mechanisms activated by angiotensin II which raise BP

Vasoconstriction and stimulation of the adrenal cortex to secrete aldosterone

39

How does vasoconstriction raise BP

Constricted blood vessels reduce the amount of blood delivered to the kidneys, which decreases they kidneys' potential to excrete water (raising BP by increasing blood volume)

40

How does stimulation of the adrenal cortex to secrete aldosterone increase BP

Aldosterone reduces urine output by increasing the retention of water and Na+ by the kidneys (raising BP by increasing blood volume)

41

How do adrenaline and noradrenaline affect BP

They are secreted by the adrenal medulla and raise BP by increasing HR and causing vasocontriction (fight-or-flight response)

42

How does antidiuretic hormone affect BP

It is produced by the hypothalamus and released by the posterior pituitary gland. Raises BP by stimulating kidneys to retain water (raising BP by increasing blood volume)

43

How does atrial natriuretic peptide affect BP

Secreted by the atria of the heart, lowers BP by causing vasodilation and by stimulating the kidneys to secrete more water and Na+ (lowering BP by reducing blood volume)

44

Which hormones raise BP

Adrenaline, Aldosterone, Angiotensin, Antidiuretic hormone

45

Which hormone lowers BP

Atrial natriuretic peptide

46

Which part of the kidney does aldosterone affect

DCT

47

Which part of the kidney does ADH affect

Collecting duct

48

What is hypertension

High blood pressure

49

What does hypertension lead to

Stroke, CHD and chronic renal failure

50

What are risk factors of hypertension

Advancing age, sedentary lifestyle, obesity (BMI greater than 25), salt sensitivity, alcohol, smoking and family history

51

What is normal BP

52

What is pre-hypertention BP

120-139/ 80-89

53

What is hypertension stage 1 BP

140-159/ 90-99

54

What is hypertension stage 2 BP

>160/ >100

55

What is secondary hypertension

When high blood pressure occurs as a result of another condition

56

What percentage of people with high blood pressure have secondary hypertension

20%

57

What conditions result in secondary hypertension

Pregnancy, Endocrine disorders, Renal disease, atherosclerosis

58

How does pregnancy result in secondary hypertension

Pregnancy results in elevated hormone levels which may result in increased responsiveness to Angiotensin II

59

What is an example of an endocrine disease that leads to secondary hypertension and how does it cause high BP

Conn's and Cushing's syndrome results in hyperaldosteronism and cortisol increases resulting in a vasoconstrictive effect

60

What does high BP result in

Increased 'wear and tear' on the heart, vessels and organs

61

What cardiac changes does high BP result in

Heart must work harder with arterial blood pressure increases. Heart muscle hypertrophies to compensate. Diffusion of oxygen from capillaries to enlarged heart becomes less efficient. Left ventricular failure will eventually occur

62

Compare normal heart and heart of someone with high BP

See diagram

63

Describe the vascular effects high BP has

  1. Narrowing of small arteries and arterioles
  2. Myogenic response due to increase in stretch
  3. Hypertrophy
  4. Response to sympathetic stimulation increased
  5. Arterioclerosis- reduction in elasticity/ hardening
  6. Rarefaction: reduction of vessels in tissues
  7. Rarefaction observed in retina and intestines of hypertensive patients

64

What are the complications of hypertension

Atherosclerosis, kidney damage, heart attack, stroke, enlarged heart- heart failure, blindness

65

What is the aim of treating hypertension

To lower cardiac output or to lower peripheral BP

66

What two drugs are used to treat hypertension

Diuretics and vasodilators

67

Give an example of a diuretic and explain how diuretics work

Thiazides. Diuretics reduce blood volume, they work by inhibiting sodium reabsorption at the beginning of the distal convoluted tubule. Water is lost as a result of more sodium reaching the collecting ducts

68

Give an example of a vasodilator and explain how they work

ACE inhibitors. Vasodilators decrease vasodilation and inhibit some renal function activities. ACE block the action of the enzymes from the lungs that convert angiotensin I to angiotensin II