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BDS1 Cardiovascular System > Arteries, veins and control of PVR > Flashcards

Arteries, veins and control of PVR Flashcards

1
Q

What are the different types of blood vessel in the CVS?

A
  • Large arteries
  • Arterioles
  • Capillaries
  • Venules
  • Veins
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2
Q

What are endothelial cells?

A

The thin layer of cells that line the interior surface of all blood vessels
- They line ALL vessels and the inside of the heart chambers

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3
Q

What are the functions of endothelial cells?

A
  • Important for local blood pressure control
  • Prevent platelet aggression and blood clot formation
  • Angiogenesis and vessel remodelling
  • Permeability barrier for nutrients/fluid between plasma and interstitial fluid
  • Release constrictors
  • Can influence proliferative state of smooth muscle cells - hypertension (can get changes in structure of blood)
  • Can release free radicals which can oxidise LDL
  • Can express molecules which tether inflammatory cells
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4
Q

What is platelet aggression?

A

The clumping together of platelets in the blood

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5
Q

What is angiogenesis?

A

The development of new blood vessels

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6
Q

Where is vascular smooth muscle present?

A

In all vessels with the exception of the smallest capillaries

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7
Q

What does vascular smooth muscle determine?

A

Determine vessels radius by contracting and relaxing

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8
Q

What does vascular smooth muscle secrete which gives the vessels their elastic properties?

A

An Extracellular matrix

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9
Q

Is which disease can vascular smooth muscle multiply?

A

Hypertension

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10
Q

What is arterial elasticity?

A

When heart ejects stroke volume of blood artery has to expand - pressure goes up to systolic blood pressure - if did not have elasticity then systolic blood pressure would be much higher

  • Compliance is important to allow large arteries to act as a pressure reservoir (allows it to expand then the vessel can recoil after blood has passed through)
  • This prevents the pressure falling to 0 as blood leaves the arteries during diastole
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11
Q

What is calcification in human arteries caused by and what can this cause?

A
  • Caused by a healing response to the presence of ‘dead cells’
  • Some cells are replaces regularly - smooth muscle cells last a long time but when they do start to die they can be replaces with calcified tissue which reduces elasticity
  • Reduces the elasticity of the vessel - BP affected
  • Increases the risk of coronary events
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12
Q

What is the basis of blood pressure?

A
  • ‘Circulation of fluid contained within a space of definite volume’ (can change the volume by opening up capillary beds - increasing the volume for blood to flow in)
  • Pressure falls as blood circulates from the left ventricle to the right ventricle (systemic circulation) and right ventricle to left ventricle (pulmonary circulation)
  • Require a certain volume per minute to satisfy metabolic demands
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13
Q

What is the ‘normal’ blood pressure?

A

120/80 but varies with age, environment etc

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14
Q

What is mean arterial pressure?

A

The average pressure pushing blood round the system

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15
Q

How can you calculate the mean arterial pressure?

A

MAP = diastolic BP + 1/3 pulse pressure

*pulse pressure is the difference between systolic and diastolic pressure

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16
Q

What are the 2 ways of calculating MAP?

A

MAP = diastolic BP + 1/3 pulse pressure

MAP = CO x TPR

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17
Q

What is arterial blood pressure?

A
  • Blood forcefully ejected into the arteries from the ventricles
  • Blood leaves the aorta (or pulmonary artery) continuously through other branches, then arterioles etc
18
Q

What is special about arteries that allows them to be able to withstand raised pressure?

A
  • They have elastic muscular walls
19
Q

What is the structure of major arteries and why?

A
  • They have very thick walls which are elastic as they contain a small amount of blood at high pressure
20
Q

What is the structure of arterioles and why?

A
  • A variable resistance system which distributes the blood - dissipate most of the pressure
  • They are much smaller in terms of diameter compared to arteries but still have a thick muscular wall
21
Q

What is the structure of capillaries and why?

A
  • walls are as little as one cell thick

- Have a vast surface area where the interchange of substances with the extracellular fluid of the tissues occurs

22
Q

What is the structure of venules and veins and why?

A
  • Very distensible
  • They are a collecting reservoir system which contains most of the blood at low pressure
  • They can expand to accommodate a lot of the blood
23
Q

What is an erythrocyte?

A

A red blood cell

24
Q

How much of the total blood volume is contained within capillaries?

A

About 5%

25
Q

How long are all of the capillaries in the body in total?

A

About 25000 miles

26
Q

What is the function of capillaries?

A

Exchange nutrients/waste products

27
Q

How wide are capillaries?

A

Just wide enough for an erythrocyte to squeeze through

28
Q

How thick are capillaries?

A

One cell thick to allow rapid exchange with tissues

29
Q

What is hydrostatic pressure?

A

The pressure blood is under when it enters the capillary

  • The blood in the capillaries exerts a pressure on the capillary wall
  • This tends to favour movement of fluid out of the capillary
30
Q

What is colloid pressure?

A

Caused by the presence of plasma proteins in the blood - plasma proteins usually too big to leave the capillary - pressure causes fluid to draw fluid back into the capillary due to osmotic effect
*This tends to favour movement of fluid into the capillary

31
Q

What would induce pulmonary oedema?

A

Heart failure

32
Q

In heart failure, what happens to hydrostatic pressure?

A
  • Will increase, particularly in extremities
33
Q

What is the net filtration of tissue fluid per day NOT including the kidneys?

A

Approximately 4 litres per day

34
Q

What does a build up of tissue fluid lead to?

A
  • Oedema

- The body must move this fluid from the tissues back into the blood

35
Q

What is the system used to move tissue fluid from the tissues back into the blood?

A
  • The lymphatic system
  • The lymph vessels, like veins, can contract to aid the movement of fluid
  • This system is also responsible for moving absorbed fat into the circulation
36
Q

What is the function of alpha-1 adrenoreceptors?

A
  • Decrease vasoconstrictor tone

- No direct change in HR or CO

37
Q

What is the function of non-selective adrenoreceptors?

A
  • Decreased vasoconstrictor tone

- Not used therapeutically

38
Q

What is active hyperaemia?

A

Changes in O2/CO2/cellular metabolites can dilate arterioles

39
Q

What is reactive hyperaemia?

A

Blocking blood temporarily

- ,A brief increase in blood flow following restoration of the blood supply

40
Q

What is flow regulation?

A

The intrinsic capacity of arterioles to respond to changes in the arterial pressure by a change in the diameter of the vessel so as to maintain constancy of the blood flow

BDS1 Cardiovascular System (6 decks)

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