Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

BS - Cardiovascular System > Coronary Circulation & Tissue Perfusion > Flashcards

Coronary Circulation & Tissue Perfusion Flashcards

1
Q

When does the heart perfuse itself and why?

A

During diastole

There is more time for it to perfuse itself during diastole

During systole it is perfusing the rest of the body

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is the heart’s main source of energy?

A

Fat as it carries more ATP per gram

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What is used if a coronary artery is blocked?

A

A coronary artery bypass

This involves taking a vessel from the leg to work as a graft to bypass the blockage

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What are the two types of graft?

Which lasts longer and why?

A

Arterial and venous

Arterial grafts last longer as arteries have thicker walls

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

How long does an arterial graft work?

A

12-15 years

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is the main function both upstream and downstream of the capillary?

A

Conduction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is the blood pressure like upstream of the capillary?

Why?

A

Higher blood pressure is being delivered by the arterial system

The arteries have more muscle in their tunica media

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is the purpose of elastic tissue in the arteries?

A

It stores energy during systole and then recoils to propel the blood along

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

How is the elastic recoil of the arteries damaged in an aneurysm?

A

There is damage to the elastic tissue

The arterial lumen is dilated

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

How does the composition of the arteries change as you get closer to the capillaries?

A

The proportion of muscle in the artery increases

They change from being elastic arteries to muscular arteries

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What is the role of resistance vessels in blood distribution?

A

They decide how much blood different parts of the body require

They supply the correct amount of blood for maximum efficiency

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What is blood flow like in a capillary?

A

There is a single-file line of RBCs

It is a continuous flow of blood that is not pulsatile

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What is the role of counter-pulsation?

A

It helps to smooth the flow of blood so that the blood is moving at all times

This gives the maximum amount of time to exchange substances across the capillary

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Where are capillaries positioned in relation to cardiac myocytes and why?

A

The capillaries are in close proximity to the cells

Cardiac myocytes need a lot of perfusion as the heart is working all the time

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What happens to capillaries in the myocardium during systole?

A

Contraction of the heart compresses the capillaries

It is difficult for blood to flow through them

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

If there are plaques present in the capillaries in the myocardium, how does this affect relative pressures?

A

The pressure must be higher in the arterioles than in the capillaries

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

How does the heart compensate for plaques in the myocardium capillaries?

A

It dilates the blood vessels or increases the force of contraction

This increases the pressure of the blood

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

From the aorta to the capillary venules, what is the branching pattern of blood vessels?

A
  1. aorta
  2. pre-arterioles (200-500 micrometres)
  3. arterioles (40-100 micrometres)
  4. smaller arterioles (<40 micrometres)
  5. capillary venules
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

In relation to the epicardium and endocardium, where are the capillary venules found?

A

Closer to the endocardium

The pre-arterioles are closer to the epicardium

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

When does perfusion of the heart occur and why?

A

During diastole

During systole, blood cannot flow through the smaller vessels due to the increased pressure in the heart

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

How does the amount of blood needed vary in hypertrophy?

A

More blood is needed to perfuse all of the muscle

There is more muscle in the ventricle walls

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

When is the main flow through the aorta and right coronary artery?

A

During systole

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

When is the main flow through the left coronary artery?

A

During diastole

There is little flow in the left coronary artery during systole

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

How does a myocardial infarction affect the amount of perfusion to the ventricle?

A

Myocytes in a particular region have died and become scar tissue

Scar tissue does not need perfusion as it is not contracting

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

How can compromised blood flow (e.g. blocked coronary artery) be improved?

A

Through a stent

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

As blood flow increases, what happens to the rate of metabolism in the heart?

A

The rate of metabolism also increases

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

What happens to metabolism of the heart during exercise?

A

The heart metabolises more and uses more oxygen and nutrients

It also produces more metabolites (waste products)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

How do metabolites (waste products) alter blood flow to the heart?

A

Blood vessels can sense waste products such as CO2 and lactic acid

They send a message to increase blood flow to the heart

29
Q

What is the process by which producing more metabolites leads to increased blood flow to the heart?

A

Autoregulation

30
Q

What metabolites will stimulate relaxation?

How does this affect blood flow to the heart?

A

Adenosine, CO2, H+ and K+

These cause blood vessels to dilate and increase blood flow to the heart

31
Q

How is coronary blood flow affected by different blood pressures?

A

Coronary blood flow decreases when blood pressure is lower

It increases when blood pressure is higher

32
Q

What is involved in autoregulation?

A

Adjusting resistance and dilation of the arteries to smooth out the perfusion to the heart

33
Q

What does autoregulation allow for?

A

Providing maintained coronary blood flow to the heart

34
Q

How does normal cardiac output vary from during rest and during exercise?

A

Normal cardiac output is 5L per minute

This can increase to 20L during exercise

35
Q

What 2 factors work to increase the cardiac output during exercise?

A
  1. increasing the heart rate

2. increasing the volume of blood pumped out of the heart with each beat (stroke volume)

36
Q

What is required in order for the heart to maintain a high cardiac output?

A

A lot of adaptation

37
Q

Where is nitric oxide produced?

A

Endothelium

38
Q

How does blood flow affect nitric oxide production by the endothelium?

A

Increased blood flow means that more nitric oxide is produced

39
Q

What is the effect of nitric oxide on blood vessels?

A

It causes the blood vessels to dilate more

40
Q

How is the endothelium stimulated to produce nitric oxide?

A

The endothelium senses the blood flow and experiences sheer stress due to the blood flowing past it

Blood flow stimulates it to produce nitric oxide

41
Q

What is produced by the parasympathetic nervous system that affects blood vessels?

What is its effect?

A

Acetylcholine

It causes the blood vessels to relax (dilate)

42
Q

What is produced by the sympathetic nervous system that affects blood vessels?

What is its effect?

A

Noradrenaline

It causes blood vessels to contract through action on alpha receptors

43
Q

How does adrenaline affect blood vessels?

A

It causes blood vessels to dilate

44
Q

What are ‘endo-en paracrine’ influences on blood vessels?

A

They are locally produced hormones

  1. angiotensin II
  2. bradykinin
  3. histamine
45
Q

How does histamine affect blood vessels?

A

It is a vasodilator which is released in response to inflammation

46
Q

How does bradykinin affect blood vessels?

A

It is produced by the endothelium during exercise

It causes dilation of blood vessels

47
Q

What are the metabolic influences on blood vessels?

A
  1. pCO2, H+, K+
  2. adenosine
  3. pO2
48
Q

What are extravascular influences on blood vessels?

A

compression

49
Q

What is the effect of adenosine on blood vessels?

A

It causes blood vessels to dilate (coronary and all over the body)

This increases blood supply to the heart

50
Q

What is the diameter and length of a capillary?

A

diameter: 5 - 10 micrometres
length: 0.5 - 1 mm

51
Q

What are capillaries made from?

A

A single layer of endothelial cells

This is surrounded by a basal lamina

52
Q

what is the blood cell viscosity of capillaries?

A

They have a slow blood cell velocity of approximately 0.3 - 1.0 mm/sec

53
Q

What is the diffusion distance like between each capillary and the cell it serves?

A

There is a short distance between each capillary and the cell it serves

54
Q

What are intercellular junctions like between cells?

A

Junctions between capillary cells are “tight”

55
Q

What are the 2 exceptions to capillary cell junctions being “tight”?

A

In the liver and bone marrow there are large clefts between cells

56
Q

Why are there large clefts between capillary cells in the liver and bone marrow?

A

Cells are leaving and entering the circulation at this point

The holes allow larger blood cells to enter or exit the circulation

57
Q

What would happen if there were large clefts between capillary cells all over the body?

A

There would be swellings as too much fluid would leak out of the capillary

58
Q

What are the capillaries like in the central nervous system?

A

The “blood-brain barrier” in the CNS has capillaries which are very tightly bound together

59
Q

Why are the capillaries tightly bound together in the brain?

A

To prevent swelling in the brain

This causes headache due to a pressure on the nervous system

60
Q

What are the types of blood vessels which lead to the capillary beds?

A
  1. collateral arteries
  2. arterioles
  3. metarterioles
  4. capillary
61
Q

What is a metarteriole?

A

a short microvessel in the microcirculation that links arterioles and capillaries

62
Q

What is a precapillary sphincter?

A

a band of smooth muscle that adjusts blood flow into the capillaries

63
Q

Where is a precapillary sphincter found?

A

at a point where the capillary originates from the metarteriole

64
Q

What is an arteriovenous anastomosis?

A

a connection between an artery and a vein

blood flows from an artery to a vein without passing through a capillary network

65
Q

What are the 2 different types of capillary?

A
  1. continuous capillary

2. fenestrated capillary

66
Q

What is a continuous capillary and what is its composition like?

A

the endothelial cells provide an uninterrupted lining

only small molecules, such as water and ions, can pass through intercellular clefts

67
Q

where are continuous capillaries found?

A

blood-brain barrier

68
Q

What is a fenestrated capillary and what is its composition like?

A

they contain fenestrations or pores which allow larger cells to pass through

69
Q

How is blood flow to the capillaries controlled?

A

By resistance vessels

These are arterioles that determine how much blood enters the capillaries and perfuses an organ/tissue

BS - Cardiovascular System (20 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions