Lecture 13: Circulatory System Flashcards

1
Q

3 basic layers of circulatory vessels

A
  1. Tunica intima
  2. Tunica media
  3. Tunica adventitia
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2
Q

Tunica intima

A

Inner epithelium + associated CT. Smooth and non-thrombogenic

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3
Q

Tunica media

A

Between intima and adventitia; vessel-associated muscle and supporting CT (esp. elastic fibers)

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4
Q

Tunica adventitia

A

Adventitial CT

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5
Q

Heart “vessel” layers

A

Inner to outer:
-Endocardium
-Subendocardium
-Myocardium
-Subepicardium
-Epicardium aka visceral layer pericardium
-Parietal pericardium
-Fibrous pericardium

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6
Q

Major artery features

A

Aka elastic arteries: tunica media has lamellar units. Also has internal/external elastic laminae + scattered media elastic fibers

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7
Q

Lamellar units

A

Alternating elastin/sm. muscle lamellae

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8
Q

Arteriole features

A

Similar to elastic arteries but smaller, roughly 1-3 smooth muscle layers. Primary resistance modulator via dilation/constriction

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9
Q

Capillary features

A

No smooth muscle, no tunica media. Always v. small, 1 RBC diameter or less. Can exchange via pinocytosis.

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10
Q

Venules

A

Look the same as capillaries (no tunica media, no sm. muscle), but slightly larger, ~5-6 RBCs across

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11
Q

Veins

A

Usually travel with companion arteries. Have a smaller tunica media and one-way valves

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12
Q

Large veins (vena cava type)

A

Contain longitudinal adventitial smooth muscle, controlling compliance and thus capacitance

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13
Q

Smooth muscle innervation

A

Sympathetic innervation (v. little parasymp.); nervi vascularis contained in tunica adventitia. Main NTs are NE and neuropeptide Y (NPY). Symp. stim. increases Ca++ influx via GPCRs increasing contraction.

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14
Q

Vasa vasorum

A

Vessels supplying outer vessel walls

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15
Q

Compounds mediating vasoconstriction

A

Endothelin, thromboxane, angiotensin II, ADH (vasopressin) are all common vasoconstrictors

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16
Q

Compounds mediating vasodilation

A

NO, ANP via cGMP, adenosine, prostacyclin, β-receptor agonists via cAMP are common vasodilators

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17
Q

Endothelial vasodilator secretion

A

The endothelium itself locally secretes many vasodilators e.g. NO; dysfunction can lead to reduced dilation capacity

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18
Q

Capillary types

A

Based on wall opening width
1. Continuous
2. Fenestrated
3. Sinusoidal

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19
Q

Continuous capillaries

A

No passive transport across endothelium; active transport via caveolae; e.g. lung, placenta, muscle, CNS

20
Q

Fenestrated capillaries

A

Contain openings for free passage of small molecules; e.g. endocrine glands, kidney, gall bladder, intestinal tract

21
Q

Sinusoidal capillaries

A

Contain large openings, sometimes large enough for cells; e.g. liver, spleen, bone marrow

22
Q

Pericytes

A

Cells often associated w/ basal small vessel surfaces; almost 1:1 w/ endothelial cells in brain. Contractile role in slow modulatory blood flow control. Organ specific w/ high plasticity.

23
Q

Lymphatic vessel features

A

Minimal structure/layers. Contain one-way valves and lymph fluid.

24
Q

Vascular compartment

A

Systemic vasculature is separated from CT space. Epithelia especially is avascular and the basement membrane prevents angiogen./migration. Vascular-CT transport is regulated by endothelial cells and usually occurs only in thin-walled vessels; large tunica media limits transport.

25
Q

Lymphatic compartment

A

The lymphatic compartment is largely permeable distally; endothelium acts as one-way valve w/ unrestricted flow from CT to lymphatics while they are at lower P

26
Q

Specialized vasculature cells

A

-Aerocytes (lungs)
-Liver Sinusoidal Endothelial Cells (LSECs, liver)
-Pericytes
-Baroreceptors
-Chemoreceptors

27
Q

Baroreceptors

A

Sensitive stretch receptors that innervate large vessels and signal the brain stem for baroreflexes. Loss of baroreflex -> orthostatic hypotension (standing posture)

28
Q

Chemoreceptors

A

Signal elevated CO2 levels to the brain stem, triggering reflex responses e.g. faster RR

29
Q

Vasculogenesis vs angiogenesis

A

Development vs elaboration of vasculature

30
Q

Start of vasculogenesis

A

First vasculature forms in extraembryonic mesoderm along the yolk sac as blood islands surrounded by endothelial cells

31
Q

Angiogenesis triggers

A

Induced by low tissue oxygen and secreted growth factors e.g. Vascular Endothelial Growth Factor (VEGF)

32
Q

2 divisions of circulation

A
  1. Blood-vascular (CV)
  2. Lymphatic
33
Q

Function of elastic artery lining

A

Elasticity dampens pulsatile flow from heart (flow is more consistent) and also acts as energy/pressure reservoir

34
Q

Thrombus vs embolus

A

Thrombus = clot formed in CV
Embolus = anything moving around in CV; -Arterial = away from heart toward smaller vessels
-Venous = toward heart via larger vessels

35
Q

Anastamosis

A

Joining of 2 vessels

36
Q

Pericardium layers

A

Outer to inner: fibrous pericardium -> parietal serous pericardium -> visceral serous pericardium (epicardium)

37
Q

Cardiac tamponade

A

Bleeding into pericardial space, compresses the heart

38
Q

Coronary arteries

A

Left and right; arteries supplying the heart. First branches off of the aorta. Blood drains through heart wall to coronary sinus (main vein of heart) which returns to right atrium.

39
Q

Cardiac skeleton

A

RIngs around valves which insulate impulse conduction. This enables coordinated, regular contraction. Fibrillation occurs without cardiac skeleton.

40
Q

Aneurysm

A

Local one- or both-sided dilation due to wall weakness; bulge creates turbulent flow.

41
Q

Dissection

A

Extravasation of blood into the tunica media; offsets intima from vessel wall and creates false lumen. Danger of bursting or shutting of flow to branches

42
Q

Leukocyte migration points

A

Post-capillary venules are primary location of diapedesis, which is why large veins are often found near large immune cell depots.

43
Q

Atherosclerosis pathogenesis

A

Endothelial injury increases permeability increasing platelet/monocyte adhesion -> LDLs, monocytes enter subendothelium. LDL oxidation, foam cell development, sm. muscle fibers create fatty streaks which calcify. Plaques may ulcerate to create a thrombus.

44
Q

Grafts vs flaps vs reconstructive flaps

A

Grafts can be partial or full thickness (partial vs full dermis). Flaps contain subQ vascular plexus for perfusion while grafts can perfuse through fluid alone.
Reconstructive flaps can even include tissue + part of original blood supply.

45
Q

Flap perfusion

A

All flaps require adequate arterial inflow and venous outflow (must prevent clotting)