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Block 3 > HRR: special circulatory systems > Flashcards

HRR: special circulatory systems Flashcards

1
Q

What is the Circle of Willis?

A

A circulatory system in the brain composed of internal carotid and vertebral arteries.

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2
Q

What are distribution arteries?

A

Those that penetrate the brain.

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3
Q

What is special about the lymphatic system in the brain?

A

There isn’t one!

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4
Q

The brain is intolerant of…

A

Edema and ischemia.

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5
Q

What is special about capillaries in the brain?

A

They’re very specialized; contain lots of tight junctions and astrocytes that help form the blood-brain barrier.

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6
Q

What is the blood-brain barrier permeable to?

A

O2, CO2, and water.

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7
Q

The blood-brain barrier has special transporters for…

A

Glucose and some drugs.

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8
Q

Describe the plasma colloidal pressure of the blood-brain barrier.

A

Super high.

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9
Q

What is the primary method of flow regulation in the brain?

A

Myogenic aka autoregulation.

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10
Q

After what pressure of CO2 in arterioles does slight pressure increases cause large flow increases?

A

40.

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11
Q

After what pressure of O2 in arterioles does further pressure increase not alter flow?

A

60.

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12
Q

The main vessels are… (heart layer)

A

Epicardial.

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13
Q

How does blood get to the endocardium?

A

Distributing arteries that penetrate the heart muscle.

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14
Q

Is there anastomoses of arteries and veins in the heart?

A

Yes.

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15
Q

What is the density of capillaries like in the heart?

A

Very high density.

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16
Q

In the heart, most venous blood is returned to the __

A

Coronary sinus via the great cardiac vein.

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17
Q

What are thebesian veins?

A

Veins that return venous blood to the left atrium…quirky. Represents a ‘shunt’.

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18
Q

The RCA distributes blood to the __

A

Posterior papillary muscles.

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19
Q

The LAD distributes blood to the ___

A

Front of the heart and apex of left ventricle.

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20
Q

The anterior papillary muscle is supplied by __ and ___

A

LAD and circumflex artery.

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21
Q

What is the major method of flow regulation in the heart?

A

Metabolic!!

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22
Q

How does adenosine impact flow in the heart?

A

Increases flow.

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23
Q

How does increased tissue potassium impact flow in the heart?

A

Increases flow.

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24
Q

Describe tissue contraction as a means of flow regulation in the heart.

A

As myocytes contract, they push against capillaries around them, causing the capillaries to collapse. This decreases blood flow. This decrease will encourage increased flow from larger vessels.

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25
Q

When is the left coronary blood flow at its largest in the cardiac cycle?

A

Isovolumic relaxation.

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26
Q

Most blood flow to the heart itself happens during ___

A

Isovolumic relaxation and filling.

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27
Q

When is blood flow highest in the right coronary artery during the cardiac cycle?

A

Systole.

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28
Q

What layer of the heart has the highest blood flow requirement?

A

The endocardium.

29
Q

How does an increase in heart rate impact blood flow to the heart?

A

It directly increases it! If HR goes up two-fold, blood flow goes up two-fold.

30
Q

What is hyperemia?

A

Increased flow after a brief period of ischemia.

31
Q

What is myocardial stunning?

A

Deficit in myocyte function for a period after perfusion is restored.

32
Q

What is coronary steal?

A

Redirection of blood from an area of higher resistance to another when coronary vessels are dilated. For example, if there is a plaque in an artery, local mechanisms will cause vasodilation in order to allow for flow through the vessel. As a result, general vasodilation preferentially lowers resistance in another part of the vasculature, causing increased flow to the normal area and lowers blood flow in the ischemic area.

33
Q

What are feed arteries?

A

They’re vessels found just outside of skeletal muscle tissue. They have high resistance at rest and are a large contributor to total peripheral resistance.

34
Q

What is a major contributor to total peripheral resistance?

A

Skeletal muscle.

35
Q

How does exercise increase flow to skeletal muscle?

A

Via sympathetic nervous system activation, other vessels get constricted and flow is directed to skeletal muscle.

36
Q

What metabolites cause a local vasodilation?

A

Lactate, potassium, adenosine.

37
Q

Is tissue contraction a factor in blood flow of skeletal muscle?

A

Yes!

38
Q

What is the skeletal muscle pump?

A

Skeletal muscle contraction in lower extremities causes the upper valve of a vein to open more and the lower vein to close slightly, pushing blood upward and toward the heart. When the muscle relaxes, the upper valve closes to prevent backflow and the lower vein opens to accept more blood.

39
Q

How does exercise impact resistance in the vessels of exercising muscles?

A

It drops way down; this is largely due to local metabolites.

40
Q

What is splanchnic circulation?

A

Flow to liver, spleen, stomach, and intestines.

41
Q

How much of blood flow to the liver comes from the portal vein?

A

75%.

42
Q

What is the central lacteal?

A

Structure that seems interwoven with vessels that accepts fats.

43
Q

What kind of capillaries are found in the splanchnic system? What is the significance of this?

A

Fenestrated; allows for more nutrient exchange!

44
Q

What is the major flow regulation mechanism in the splanchnic circulation?

A

Neural (SNS and PSNS).

45
Q

Is tissue contraction a factor in splanchnic circulation?

A

No.

46
Q

How does the liver equalize arterial and venous pressure? What does this do?

A

Dumping blood from both into the sinusoids, where it mixes. This pressure equalization helps prevent reflux.

47
Q

What happens to the liver if pressure in the IVC builds up?

A

It throws off the pressure system and increases congestion in the portal vein; this will lead to ascites.

48
Q

How does increased sympathetic flow impact splanchnic circulation?

A

It decreases blood flow to them; it also causes the liver to put more blood into the circulation.

49
Q

What are the nutritional requirements of cutaneous circulation?

A

They’re pretty low.

50
Q

What is the significance of cutaneous circulation?

A

Plays a huge role in thermoregulation.

51
Q

What are ‘radiators’ in apical skin?

A

a-v anastomoses; opening them allows for more flow distribution to the skin.

52
Q

What is the main method of regulation of flow in cutaneous circulation?

A

Neural.

53
Q

What is a major factor of flow regulation in nonapical skin?

A

Cholinergic sympathetic fibers that cause sweat release.

54
Q

What induces vasodilation in nonapical skin?

A

Bradykinin and actions of vascular smooth muscle.

55
Q

What is reactive hyperemia?

A

When flow resumes following a period of ischemia, the increased flow can cause reddening of the skin.

56
Q

What is cold-induced vasodilation?

A

Alternating vasoconstriction and vasodilation of blood vessels subjected to periods of extreme cold; this is protective against cold damage.

57
Q

What is white reaction?

A

A blanched line appears in the trailing path of a short instrument mildly stroking the skin.

58
Q

What is the triple response?

A

A stronger stimulus causes reddening of the injury and surrounding tissue as well as causing localized edema.

59
Q

What is the foramen ovale?

A

Allows blood to flow from the right to left atrium.

60
Q

What is the ductus venosus?

A

It helps bring blood from the placenta through the fetal liver to get nutrients to it; it combines with the IVC to bring blood to the right atrium.

61
Q

Which side of the fetal heart is the high-pressure side?

A

The right side.

62
Q

Describe pulmonary vascular resistance in a fetus.

A

It is super high; this is because they don’t need to pump much blood to the lungs since they don’t use them to breathe; they really only need to give them enough blood to keep the tissue alive.

63
Q

What is the ductus arteriosus?

A

It shunts blood from the pulmonary artery to the aorta to redirect it; this lets the blood go into the system/brain as opposed to the lungs.

64
Q

What maintains the patency of the ductus arteriosus?

A

PGE2 and hypoxia (don’t need use of lungs).

65
Q

Does fetal hemoglobin have higher or lower affinity for oxygen?

A

Higher.

66
Q

What happens to fetal circulation within the first day of birth?

A
  1. Left heart becomes higher pressure due to lungs transitioning to accepting oxygen; this results in a lowering of the pressure in the right ventricle, making the left side of the heart higher pressure.
  2. Foramen ovale closes.
  3. Ductus arteriosus functionally closes.
67
Q

When is the ductus arteriosus anatomically closed?

A

After about a month due to decreased PGE2.

68
Q

What causes the foramen ovale to close?

A

LA pressure exceeds that of the RA.

Block 3 (29 decks)

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