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sem 2 CVS > Intro to CVS > Flashcards

Intro to CVS Flashcards

1
Q

Why do we need a CVS?

A
  1. Temperature regulation- for warm blooded organisms, only operate within a small temperature range. Vasodilation and vasoconstriction accordingly.
  2. Pump blood through lungs and carry oxygen
  3. Transport nutrients to muscles and organs, as well as transport waste away
  4. Circulates hormones and immune mediators- CVS is used as a mean of signalling, where receptors may be far away from where hormone is produced
  5. Connection to the lymphatic system, returning fluid to the blood, consists of immune cells
  6. Human reproduction, blood flow for erection and also hormonal signalling for reproduction
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2
Q

define passive diffusion, and what is it good for?

A

the random undirected thermal movement of molecules from an area of high conc to an area of low conc

it is a good way of moving substances over short distances

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3
Q

the time needed to diffuse a given distance is proportional to what?

A

the square of the distance

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4
Q

what distance is diffusion greater over, short or long?

A

short. Diffusion is fast in um but very time consuming over distances >1mm, and inappropriate for transport throughout the body.

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5
Q

Does the nervous system operate slowly?

A

No, it operates very quickly- distance across synapse of 0.1 um, with a time of 0.005ms.

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6
Q

what about oxygen and glucose transport

A

o2 and glucose go from a small capillary into an adjacent cell, 10um distance and time it takes is 50ms

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7
Q

larger sizes?

A

diffusion takes too long

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8
Q

oxygen and glucose around cartilage?

A

8 mins for 1mm

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9
Q

the CVS uses convection, what does this provide?

A

fast and directional transport

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10
Q

what is the CVS transport determined by and how is it driven?

A

CVS determined by a pressure gradient, and the heart uses metabolic energy to create a pressure difference, so fluid moves from an area of high pressure to low -pressure

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11
Q

what is diffusion critical for?

A

transport over short distances

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12
Q

what does the output of blood at high pressure create? (with stats)

A

a pressure difference with distant blood vessels

  • aorta> 100mmHg
  • large veins 5-10 mmHg
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13
Q

what are systole and diastole?

A

systole- contraction

diastole- relaxation

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14
Q

the heart is a four chambered what?

A

four chambered muscle

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15
Q

direction of pumping?

A

RHS of heart –> pulmonary arteries –> lungs –> pulmonary veins –> LHS of heart

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16
Q

name the only artery that carries deoxygenated blood?

A

the pulmonary artery

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17
Q

why is pressure created in the left ventricle?

A

pressure is created for pumping blood everywhere, with the aorta leaving the heart

18
Q

pressure of the blood leaving the heart via the aorta and pressure of the blood entering the heart via the superior and inferior vena cava (ie. the pressure differential)

A

leaving- 100mmHg

entering- 5mmHG

19
Q

1- what is the valve located between the left atrium and left ventricle?

2- what is the valve located between right atrium and right ventricle?

A

1- the mitral valve

2- tricuspid valve

20
Q

Cardiac output?

A

Kidneys- 20%. Filter blood and get rid of waste, and so need to perfuse kidneys very well.

Muscle- 20%. For muscle contraction.

Brain- 13%. Needs o2 and glucose all the time.

Liver and GI- 25%. Needs to absorb from food and detoxify.

Myocardium- 4%

Other- 18%

21
Q

Cardiac output in terms of what the heart needs?

A

needs oxygen and glucose itself, to create a pressure gradient to transport blood from different regions.

22
Q

the myocardium and the brain are relatively under perfused- how do they overcome this?

A

the brain has special mechanisms to ensure it is always working, as does the myocardium.

23
Q

what potential clinical problems does being under perfused cause? and what do you have to carefully control as a result?

A

Angina, MI, stroke triggered by relatively moderate fall in perfusion. As a result you need to carefully control cardiac output.

24
Q

oxygen consumption %

A

Kidneys- 10%

Muscle- 20%

Brain- 18%

Liver and GI- 30%

Myocardium- 10%

Other- 12%

25
Q

what is cardiac output? (and equation)

what is cardiac output at rest vs during exercise?

A

the volume of blood ejected from the heart per minute
cardiac output= heart rate x stroke volume
at rest 5 litres/min
exercise 20 litres/min

26
Q

does the blood go to organs in a series?

A

no, it goes in a parallel

27
Q

define stroke volume

A

the amount of blood expelled each time the heart/ventricle contracts ie. each heartbeat

28
Q

what is starlings law?

A

filling pressure- occurs as the left ventricle gets filled from the left atrium from the lungs, there is some stretch on the heart wall. When the heart is stretched it contracts harder, meaning more blood comes back to the heart.

29
Q

does parasympathetic or sympathetic innovate the heart, and what does it cause? how does it work?

A

sympathetic, and it causes contraction of heart harder.

Adrenaline released from adrenal glands in circulation binds to β1 receptors on heart, causing contraction.

30
Q

why are blood flow and BP critical, give an example. What controls them?

A

Blood flow and BP is critical for correct bodily functioning (e.g. poor perfusion of kidneys causes renal failure and death). Blood flow is proportional to pressure across the blood vessel and inversely proportional to resistance of the blood vessel.

31
Q

what do an increase in resistance and an increase in pressure difference do?

A

an increase in resistance decreases blood flow by constricting the blood vessel

an increase in pressure difference increases blood flow.

32
Q

pulmonary is at low pressure, why is this efficient?

A

blood travels slower, allowing better gas exchange, also good because the lungs have a very delicate lining.

33
Q

what are capillaries made up of and what is the velocity like in capillaries?

A
  • capillaries are made up of millions of small vessels giving a v large c.s.a.
  • velocity is much slower in capillaries allowing nutrient exchange to occur
34
Q

what is the aorta? what does an increase in c.s.a. cause?

A

a large vessel with a low c.s.a. Increase in c.s.a. causes the blood to slow down.

35
Q

there are 2 types of circulation, series and parallel. Explain the difference.

A

Series involves the same blood supply between organs, and its medically significant if the first organ is under perfused. Arteries to intestines and then liver, which removes toxins from blood.

Parallel means the cardiac output is split up, and this safeguards oxygen supply in organs. Most organs are supplied this way.

36
Q

structure of blood vessel walls

A

Tri-laminar system (3 layers)

Inside- endothelial layer with some connective tissue behind
Middle- smooth muscle layer

37
Q

arteries vs veins smooth muscle:

A

Arterioles:

  • have much stronger smooth muscle
  • elastic fibres which are orientated longitudinally, makes arteries much springier and elastic
  • smooth muscles organised in a circular way meaning contraction can close the vessel.

Veins:

  • open up when filled with blood, but aren’t as contractile compared to arteries
  • expand a lot, can hold a lot of the blood
38
Q

how are arteries constricted and dilated, why is it important its controlled?

A
  • constricted using noradrenaline and alpha 1 receptors
  • endothelial cells produce NO which acts as a smooth muscle dilator
  • important as you want control over vessels
39
Q

what are elastic vessels?

A

arteries

40
Q

what are resistance vessels?

A

arterioles, constricting these changes resistance to flow and blood flow going through them
-control arterial BP and regulate blood flow

41
Q

what are exchange vessels?

A

capillaries

  • nutrient delivery to cells, tissues
  • water and lymph formation removal of metabolic waste
42
Q

what are capacitance vessels?

A

venules and veins

  • low pressure, can fill up with blood, big capacity to expand
  • control the filling pressure
  • most of the time blood is in veins, and if more blood is needed veins constrict and send more blood to the heart.
  • systemic veins and venues serve as a reservoir holding 65% of volume.

sem 2 CVS (17 decks)

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