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STRUCTURES - WEEK 3 > LEC 23: Heart I (Vessels, Blood, Microstructure)- Part I - 09.03.14 > Flashcards

LEC 23: Heart I (Vessels, Blood, Microstructure)- Part I - 09.03.14 Flashcards

1
Q

What are the 5 types of arteries and veins

A

Artery <—–> Large Vein

Muscular Artery <—–> Medium (muscular) Vein

Small (muscular) Artery <—–> Small (muscular) Vein

Arteriole <—–> Venule

Capillary <—–> Postcapillary Venule

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2
Q

Walls of arteries and veins are composed of (3) concentric layers (tunics)

A
  1. tunica intima (inner layer)
  2. tunica media (middle layer)
  3. tunica adventitia (outer layer)

NB: 3 tunics show different variations in different types of arteries/veins

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3
Q

Common iliac artery (H&E)

A

A. Tunica intima

B. Tunica media

C. Tunica adventitia

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4
Q

Describe the parts of the wall in this common iliac artery (H&E)

A

A. Tunica intima

  • endothelium and its basement membrane
  • subendoendothelial connective tissue

B. Internal elastic lamina

C. Tunia media

  • elastic fibers
  • collagen fibers
  • ground substance
  • smooth muscle cells
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5
Q

Describe the parts of the wall in this common iliac artery (H&E)

A

A. Tunica media

B. External elastic lamina

C. Tunica adventitia

  • loose connective tissue with collagen, some elastic fibers, fibroblasts
  • vasa vasorum (vessels of the vessel); Nerves
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6
Q

vasa vasorum

A

Latin, “vessels of the vessels”

network of small blood vessels that supply the walls of large blood vessels

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7
Q

Name this structure, found in the tunica media

A

postganglionic sympathetic nerve for vasoconstriction of the vessel wall, mediated by smooth muscles in the tunica media

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8
Q

Name the structure stained black in this slide of an elastic artery (resorcin fuchsin stain)

A
  • elastic fibers are stained black
  • sheets of fenestrated elastic membranes (laminae) = stacks of chicken wire

NB: elastic fibers are blurry pink under H&E stain

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9
Q

laminae

A

fenestrated elastic membranes found in elastic arteries

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10
Q

Describe what is shown in this slide of an elastic artery (e.g. aorta)

A
  • 40-70 sheets of fenestrated elastic membranes (laminae)
  • external and internal elastic lamina are not conspicuous
  • Vasa vasorum; nerves
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11
Q

Describe what is shown in this slide of a large vein (e.g. vena cava)

A

Tunica intima = internal elastic lamina

Tunica media = circular smooth muscle

Tunica adventitia = longitudinal smooth muscle (runs along vessel)

Vasa vasorum; nerves

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12
Q

elastic arteries

A
  • aorta and major branches are elastic arteries
  • elastic tissue in wall allows vessels to become distended when blood surges into them during systole
  • during diastole, elastic recoil of distended arteries forces more blood along the arterial vessels, thus maintaining arterial pressure in the vessels while heart is filling
  • elastic arteries are physiologically conducting vessels
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13
Q

systole

A

contraction of heart muscles

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14
Q

diastole

A

relaxation of the heart muscle

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15
Q

large veins

A
  • venae cavae are large veins
  • pressure in venous system = low
  • pressure continues to drop as veins converge towards the heart
  • walls of veins = thin, easily distensible, compliant
  • compliance of veins allows them to act as reservoir for blood collected from other areas of vascular system
  • physiologically, veins are reservoir vessels or compliance vessels
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16
Q

Describe this slide

A
  • typically occur together (nerve/artery/vein)
  • artery is much more circular
  • vein is collapsible
17
Q

Describe this slide of a muscular artery (Resorcin fuchsin stain for elastic fibers)

A

A. Internal elastic fibers (IEL)

B. Tunica media

C. External elastic fibers (EEL)

D. Tunica adventitia

18
Q

Describe this slide of a medium (muscular) vein (Resorcin fuchsin stain)

A

A. Tunica media

B. Tunica adventitia

NB: Tunica adventitia is much larger

19
Q

muscular arteries

A
  • brachial, femoral, coronary arteries
  • relatively large proportion of muscle in muscular arteries (allows for rapid distribution of blood to tissues)
  • low resistance to flow of blood (allows for rapid distribution)
  • repeated branching, muscular arteries diminish in caliber to form small muscular arteries
  • small muscular arteries feed into arterioles
  • muscular arteries = distributing arteries
20
Q

medium veins (muscular veins)

A
  • companion veins of muscular arteries
  • valves are present in muscular veins
  • physiologically, medium veins are collecting vessels
21
Q

Describe this slide

A
  • small (muscular) artery
    • tunica media = 3-10 smooth muscle layers
    • internal elastic lamina (IEL) is visible
  • small (muscular) vein
    • few smooth muscle layers in wall
22
Q

Describe this slide

A
  • arterioles
    • tunica media = 1-3 layers of smooth muscle
  • venules
    • few smooth muscle in wall, flattened, irregular shape

NB: largest artery is NOT an arteriole but a smooth muscular artery (too many layers of smooth muscle!)

23
Q

Arterioles

A
  • arteriolar diameter can be varied with great precision by contraction of the smooth muscle in response to sympathetic neural and non-neural stimuli
  • contraction increases resistance to blood flow and the pressure in the muscular and elastic arteries rises
  • physiologically, arterioles control systemic blood pressure and are called resistance vessels
24
Q

Microcirculation

A

Artery—arteriole—capillary bed—venule—vein

25
Q

Describe this slide (hint: microvasculature)

A

A. capillary

  • can only accomodate 1 red blood cell; (wall = endothelial cell)

B. Arteriole

C. Postcapillary venule

  • no smooth muscle present in postcapillary venule
26
Q

postcapillary venules

A
  • 10-25um in diameter (3x as large as capillary)
  • endothelium is more perable than capilalry
  • preferred location for emigration of white blood cells from the blood circulation, especially during inflammation
  • postcapillary venules are inflammation vessels
  • pericytes replace smooth muscle cells in postcapillary venules
27
Q

diapedisis

A

the passage of blood cells through the intact walls of the capillaries, typically accompanying inflammation

28
Q

Describe this slide

A
  • capillaries (longitudinal and transverse sections)
  • E = endothelial cell nuclei
  • Pericytes = occasionally embrace the capillary endothelial cells, may have a contractile function
29
Q

pericytes

Shown: EM of a capillary and pericyte

A
  • replace smooth muscle cells in postcapillary venules
  • outside capillaries or postcapillary venules
  • contractile proteins (actin, myosin, tropomyosin)
  • contraction serves to regulate blood flow through capillaries
  • can differetiate into smooth muscle and endothelial cells in response to injury or stimulation by growth factors
30
Q

capillaries

A
  • major site of gas/fluid/nutrient/metabolic waste products exchange between blood and tissue
  • physiologically, capillaries are metabolic exchange vessels
31
Q

classification of capillaries

A
  1. continuous
  2. fenestrated
  3. discontinuous (sinusoids)
32
Q

examples of continuous capillaries

A
  • muscles
  • brain
  • lungs
  • bone
33
Q

examples of fenestrated capillaries

A
  • intestines
  • endocrine glands
  • kidneys
34
Q

examples of discontinuous (sinusoids) capillaries

A
  • liver
  • bone marrow
  • spleen
35
Q

What is noteable about the endothelium lining the sinusoid (discontinuous) capillary

A
  • endothelium lining the sinusoid has fenestrae and lacks a basement membrane
  • allows for bidirectional flow

STRUCTURES - WEEK 3 (4 decks)

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