1. Overview of Function of the Cardiovascular System Flashcards

1
Q

What are the main functions of the cardiovascular system? (5)

A

BULK FLOW SYSTEM

  1. O2 and CO2
  2. nutrients
  3. metabolites
  4. hormones
  5. heat (thermoregulation to periphearies)
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2
Q

How many heart beats are there in 70 years of a human life?

A

over 2.5 billion (incredibly reliable)

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3
Q

Why is the heart so remarkably flexible? (what features show this?)

A
  1. pump can vary output
  2. vessels can redirect blood
  3. vessels can store blood (stored in venules which can be released into circulation when needed)
    Esp. during exercise
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4
Q

What are 2 circulations in the heart?

A
  1. systemic
  2. pulmonary
    Both pumps have reverse functions
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5
Q

What does the right side of the heart pump blood into?

A

into the lungs

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6
Q

What does the left side of the heart pump blood into?

A

into the other body areas

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7
Q

Is output from both sides of the heart equal?

A

yes, it must be equal since pumps are in series and both must deliver same amount of blood to maintain the balance

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8
Q

How are most vascular beds arranged?

A

in PARALLEL fashion

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9
Q

What is an exception for blood not travelling in parallel fashion but in series directly to another location without dilution in parallel circulation?

A

blood travelling from HYPOTHALAMUS to PITUITARY GLAND

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10
Q

What is another exception of blood not travelling in parallel but directly from one location to the next without dilution in circulation?

A

from GUT to LIVER (nutrients absorbed in gut can be directly transported to liver without having to go through parallel circulation)

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11
Q

What is the cardiac output in a normal circulation?

A

5L/min

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12
Q

What does cardiac output correspond to?

A

oxygen consumption (roughly proportional)

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13
Q

Does the brain have more cardiac output or use more oxygen consumption?

A

MORE oxygen consumption (18%)than cardiac output (13%) for complex tasks

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14
Q

Does the heart have more cardiac output or use more oxygen consumption?

A

MORE oxygen consumption (10%) than cardiac output (4%)

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15
Q

Does the skeletal muscle have more cardiac output or use more oxygen consumption?

A

Both cardiac output and oxygen consumption is equal (20%)

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16
Q

Does the skin have more cardiac output or use more oxygen consumption?

A

MORE cardiac output (9%) than oxygen consumption (2%) for flexible thermoregulation

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17
Q

Do the kidneys have more cardiac output or use more oxygen consumption?

A

MORE cardiac output (20%) than oxygen consumption (6%) for metabolic requirement for filtration

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18
Q

Do abdominal organs have more cardiac output or use more oxygen consumption?

A

MORE oxygen consumption (30%) than cardiac output (24%)

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19
Q

Why is heart so susceptible to cardiac diseases in terms of its cardiac output and oxygen consumption?

A

Only receives 4% of its cardiac output but uses 10% of the body’s o2 therefore it can’t always satisfy its oxygen requirements which is why it’s so susceptible to disease

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20
Q

What is the equation for Darcy’s law? (flow of fluid through a porous medium)

A

Flow= pressure difference (MAP-central venous pressure) / resistance

21
Q

What is blood flow and resistance controlled by?

A

controlled by radius of the vessels which selectively redirects flow

22
Q

What are the “taps” in vessels which selectively redirect flow and therefore resistance?

A

ARTERIOLES act as “taps” controlling resistance (and therefore flow) to each vascular bed by redirecting blood (some regions receive more and some less)

23
Q

What smaller vessels do arteries further divide into which give finer control of blood flow?

A

arterioles (and eventually capillaries)

24
Q

What smaller vessels do veins further divide into which give finer control of blood flow?

A

venules (and eventually capillaries)

25
Q

Describe flow of blood from left to right side of the heart and ALL blood vessels involved.

A
L.side of heart 
Aorta 
other arteries
arterioles 
capillaries (gas exchange) 
venules 
veins 
Vena Cava 
R.side of heart
26
Q

What type of artery is aorta?

A

Elastic artery

27
Q

Describe pressure and features of aorta. (3)

A
  • damp pressure variations as lots of energy can be stored in elastic walls
  • has low resistance so blood can easily get through
  • wide lumen and very thick elastic wall
28
Q

What type of artery are other body arteries?

A

Muscular arteries

29
Q

Describe the pressure and features of other body arteries.

A
  • low resistance conduit so blood can easily get through
  • wide lumen and strong non-elastic wall
  • its job is to transport blood from heart to peripheries
30
Q

What are the main resistance vessels? (high resistance)

A

arterioles

31
Q

Describe features of arterioles.

A
  • narrow lumen; high resistance
  • thick contractile wall
  • control resistance and therefore flow
  • allow regional redirection of blood
32
Q

What are the exchange vessels in the body?

A

capillaries

33
Q

Describe features of capillaries.

A
  • narrow lumen
  • very thin wall (one cell thick) for permeability and max. diffusion
  • big SA: volume ratio due to its large numbers
34
Q

What are capacitance vessels in the body? (store large amounts of intravascular blood volume)

A

Venules AND veins

35
Q

Describe features of venules and veins.

A
  • wide lumen and low resistance
  • distensible/stretchable wall
  • smooth wall muscle wall but less than arteries
  • allows fractional distribution of blood between veins and rest of circulation (esp. heart)
  • can expand and become floppy
  • store blood for fractional distribution
36
Q

What does capacitance vessels mean?

A

It means these vessels can STORE blood for when body needs it (e.g. when body needs extra blood from circulation during exercise)

37
Q

What is the name of the heart muscle (cardiac) which contracts?

A

myocardium (top layer of it is epicardium and inner layer is endocardium)

38
Q

What is the role of the atrium?

A

Receives blood and contracts

39
Q

What is the role of the ventricle?

A

Pumps the blood (contracts)

40
Q

What are the 4 valves in the heart and where are they found?

A
  1. Tricusupid valve (r.AV valve) betwen r. atrium and ventricle
  2. Mitral valve (l.AV valve) between l. atrium and ventricle
  3. pulmonary valve (semilunar) between l. ventricle and pul.artery
  4. aortic valve (semilunar) between r. ventricle and aorta
41
Q

What is the function of heart valves?

A

prevent backflow of blood

42
Q

What do papillary muscles and chord tendinae ensure?

A

They ensure valves don’t turn inside out (prevent prolapse and eversion); they connect to valve flaps

43
Q

What are cord tendinae mainly made up of?

A

80% collagen and some elastin fibres

44
Q

What 2 things are cord tendinae attached to?

A
  1. edges of the valve flaps

2. papillary muscles

45
Q

What do papillary muscles do?

A

Provide stability for chord tendinae

46
Q

What causes valves to open and close?

A

Changes in pressure (NOT due to chord tendinae or papillary muscles). Valves open and close PASSIVELY when blood pushes on them

47
Q

What are 2 main septa?

A
  1. interatrial septum

2. interventricular septum

48
Q

What is included in the pulmonary trunk?

A

Originates in the right atrium and branches into r. pulmonary artery and l. pulmonary artery