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Microanatomy > Blood Vessels > Flashcards

Blood Vessels Flashcards

1
Q

tunica intima

  • components
  • special in artery
  • functions
A

endothelium, basement membrane, subendothelial loose CT

  • arteries have internal elastic lamina bordering media (fenestrated layer of elastin)
  • forms permeable/semi-permeable barrier
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2
Q

tunica media

  • components
  • what makes ECM
  • what do larger vessels have?
  • what replaces it in capillaries and venules?
  • functions
A

smooth muscle, variable elastic fibers and lamellae, reticular fibers, proteoglycans

  • ECM made from smooth muscle cell
  • larger vessels have external elastic lamina
  • pericytes replace media
  • controls diameter, BP, movement
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3
Q

tunica adventitia

  • components
  • what do larger vessels have?
  • functions
A

fibroblasts, longitudinal collagen, elastic fibers

  • larger vessels have vasa vasorum (vessels of vessels to supply with O2)
  • -more extensive in veins b/c low nutrient and O2 content of venous blood
  • provides physical support, attaches vessels to tissue, and carries vessels and nerves
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4
Q

endocardium

-components

A

homologous to intima; lining atria and ventricles

-made of endothelium and subendothelium layer of CT

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5
Q

myocardium

-components

A

homologous to media; thickest layer of the heart wall

-made of cardiac muscle thicker in ventricles than atria

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6
Q

epicardium

-components

A

homologous to adventitia; forms surface of heart and anatomicalloy defined as visceral layer of pericardium
-made of mesothelium and subepicardial layer of loose CT that has nerves, adipose, and coronary blood vessels

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7
Q

large, elastic, conducting arteries location and functions

A

aorta and main branches, common carotid, brachiocephalic, subclavian, and pulmonary arteries are elastic arteries

  • systole distends the elastic arteries, recoil and contract during diastole
  • -produces more uniform flow
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8
Q

intima of elastic arteries

A

150 microns thick in adults (1/6 thick)

  • scattered smooth muscles in subendothelial layer
  • endothelial cells have Weibel-Palade bodies (membrane-bound inclusions) with dense matrix with von Willebrand factor
  • endothelial cells are elongate polycons w/ long axes oriented w/ long axes oriented w/ blood flow and cells are connected by occluding junctions
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9
Q

media for elastic arteries

A

2 mm thick, made of 40-70 layers of fenestrated elastic lamellae with smooth muscle between
-thin external elastic lamina and vasa vasorum of adventitia penetrates outer third to half of it

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10
Q

adventitia of elastic arteries

A

relatively thin layer with nerve fibers, lymphatics, and vasa vasorum in loose CT

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11
Q

mixed musculo-elastic arteries location and functions

A

forms parts of terminal abdominal aorta, the iliac arteries, external carotids, axillary arteries, etc.
-these are transitional segments between large and medium arteries

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12
Q

histology of mixed musculo-elastic arteries

A

tunica media and adventitia are the same thickness

-media has fewer elastic lamellae, and more obvious internal elastic membrane

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13
Q

location and functions of medium muscular, distributing arteries

A

most named arteries (coronary, renal, etc.)

-distribute blood to tissues and organs regulated by ANS control of media

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14
Q

intima of medium, muscular distributing arteries

A

thin and has prominent internal elastic lamina that undulates

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15
Q

media of medium, muscular distributing arteries

A

relatively thick and made of many concentric layers of smooth muscle bound in larger muscular arteries by external elastic lamina that gets thinner and disappears in smaller diameter specimens

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16
Q

aventitia of medium, muscular distributing arteries

A

as thick as the media

-vasa vasorum and lymphatics are poorly developed

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17
Q

arterioles feneral features and functions

A

100 microns or less in diamter, invisible to naked eye

-function to maintain normal blood pressure in arterial system, and reduce pressure of blood entering capillaries

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18
Q

intima of arterioles

A

thin subendothelial layer of reticular fibers and internal elastic membrane is absent in smallest arterioles

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19
Q

media of arterioles

A

composed of one to five layers of smooth muscles

20
Q

adventitia of arterioles

A

moderate to scant

21
Q

metarteriole

A

(also precapillary sphincter)

terminal segment from an arteriole before a capillary bed that regulates blood flow into capillaries

22
Q

structural changes of arteries with age

A

three tunics are compete during 4th month in utero

  • largest arteries grow until age 25
  • aging process involves intima and media
  • after 30 years, media becomes stiffer from increase in elastic lamellae, and deposition of collagen and proteoglycans
23
Q

large elastic artery changes with age

A

change more than muscular arteries

  • in media, elastic tissues develop irregular thickenings and elastic fibers can fragment
  • plaques from in intima due to noncellular lipid material accumulating in subendothelial layer
24
Q

muscular artery changes with age

A

change less than elastic arteries

  • undergo calcification of media
  • form plaques in intima that reduce diameter as early as 25 years
25
Q

dimensions and components of capillaries

A

smallest vascular channels, with average diameter of 5 to 10 microns, 0.05 to 1 mm length

  • 60,000 miles of capillaries in human body
    components: endothelial cells and pericytes
26
Q

capillary endothelial cells

  • components
  • struture
  • life span
  • secretions
A

cytoplasm w/ Golgi, mitochondria, RER, free ribosomes, pinocytotic vesicles

  • structural support from desmin and/or vimentin (intermediate filaments)
  • life span of 150-180 days, slowly renewing
  • secrete basal lamina, joined by tight and gap junctions\; also makes bioactive substances (collagens I, III, IV, V, fibronectin, laminin, anticoagulants)
27
Q

capillary pericytes

  • structure
  • what do they share with endothelial cells?
  • function
A

stellate cells around capillaries and post-capillary venules

  • extensive branching processes with large nuclei rich in heterochromatin, small Golgi, mitochondria, RER, and filaments extending into processes
  • share basal lamina of endothelial cells
  • contract to regulate blood flow, and serve as stem cells for endothelial and smooth muscle cells after injury
28
Q

types of capillaries

A

continuous
fenestrated
sinusoids

29
Q

continuous capillary location and structure/function

A

L: most common, in muscle, nervous, CT, and exocrine pancreas
S/F: endothelial lining and basal lamina are complete (sealed by tight junctions for passage of small molecules)
-cytoplasm has vesicles to transport large molecules

30
Q

fenestrated capillaries location and structure/function

A

L: pancreas, intestines, endocrine glands
-those with no diaphragm are only in renal glomerulus
S/F: continuous (thin) endothelium and basal lamina
-endothelial cells have small pores (60-80 nm) covered by diaphragm
-specialized for rapid interchange of substances between blood and tissue

31
Q

sinusoid capillaries structure/function

A

irregular blood channels that conform to shape of structure they line

  • continuous basal lamina and fenestrae with diaphragms much larger than fenestrated capillaries
  • the discontinuous types have absent/discontinous basal lamina with large gaps between endothelial cells that allows enhanced exchange between blood/tissue
32
Q

three types of sinusoid capillaries and locations

A

sinusoidal capillaries: endocrine glands
discontinuous sinusoids: liver and bone marrow
venous sinusoids: spleen

33
Q

capillary permeability (2 types)

A

small: 9-11 nm; gaps between cell junctions that allow water and small hydrophilic molecules to pass (moreso during inflammation)
large: 50-70 nm; transcytosis by pinocytotic or trans-Golgi derived vesicles

34
Q

traits of veins VS arteries

A
  • greater variation in size and structure
  • larger caliber and more numerous (contain 70% of total blood volume)
  • more extensive vasa vasorum and lymphatics
  • more collagen and less elastic susbstance and smooth muscle
  • most thickness is from adventitia
  • small and medium veins have valves that are formed from infolding of intima with elastic CT core
35
Q

large veins structure

A

intima: continuous endothelium and basal lamina, but no IEL
media: incomplete or absent
adventitia: largest, best developed (95% thickness)
- thick bundles of longitudinally oriented smooth muscle, collagen, and elastic fibers
- well-developed vasa vasorum and lymphatics

36
Q

what kinds of vessels are superior and inferior vena cava and portal vein?

A

large veins

37
Q

small and medium vein structure

A

intima: continuous endothelium and basal lamina
- complete IEL is only in leg, with some valves
media: poorly developed except in limbs; smooth muscle is circumferential
adventitia: thickest tunic and has no smooth muscle
- has collagen, elastic fibers, fibroblasts, lymphatics, and vasa vasorum

38
Q

two classes of venules

A

pericytic and muscular

39
Q

venule function

A

continue exchange of materials that begin in capillaries

  • preferred location for leukocyte emigration
  • become leaky in response to histamine and serotonin
40
Q

pericytic venules

A

post-capillary venules 10-50 microns in diameter

-resemble large capillaries b/c they have a pericyte

41
Q

muscular venules

A

reccieve blood from pericytic venules and accompany arterioles

  • media has 1-2 circular layers of smooth muscle cells
  • thin adventitia of loose CT
42
Q

portal system specializations and examples

A

carry blood from one capillary bed to another

  • hepatic portal vein between intestines and liver
  • hypophyseal portal veins of pituitary
  • efferent arterioles of renal cortex
43
Q

arteriovenous anastomoses and examples

A

direct cross connections between arterioles and venules

-smooth muscle cells form sphinchter that regulates blood flow and allows bypass of a capillary bed

44
Q

characteristics of lymphatic vessels

A

large lumen, thin wall, irregular shape, extensive branching that runs parallel to blood capillaries and veins

45
Q

functions of lymphatic vessels

A

collect lymph from extracellular spaces and return it to blood vascular system
-aid in circulation of lymphocytes

46
Q

structure of lymphatic vessels

A

lymphatic collecting vessels are like veins (endothelium intima, incomplete media, and longitudinal bundles of smooth muscle in adventitia), but more irregular in shape and size
-discontinuous or absent basal lamina, held open by elastic anchoring filaments

Microanatomy (14 decks)

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