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BIOL 112 > Lecture 3 CVS: Blood Vessels > Flashcards

Lecture 3 CVS: Blood Vessels Flashcards

1
Q

what are blood vessels

A

-a delivery system of dynamic structures that begins nad ends at the heart

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2
Q

what system do blood vessels work with

A

it works with the lymphatic system to circulate fluids

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3
Q

what are arteries

A

they carry blood away from the heart; oxygenated blood, except for the pulmonary circulation and umbilical vessels of a fetus

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4
Q

what are capillaries

A

they have direct contact with tissue cells; directly serve cellular needs
-one cell thick good for transfer of oxygen and nutrients and removal of used goods

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5
Q

what are veins

A

carry blood toward the heart; deoxygenated, except for the pulmonary circulation and umbilical vessels of a fetus

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6
Q

what is the structure of blood vessel walls

A

all consist of a lumen, central blood-containing space, surrounded by a wall

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7
Q

what are the layers of the walls in all blood vessels except for capillaries

A

there are three layers or tunica
1. tunica intima/ interna
2. tunica media
3. tunica externa

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8
Q

what are the walls in the capillaries

A

endothelium with sparse basal lamina

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9
Q

describe the tunica intima

A

-innermost layer, “intimate”
there are three layers of the tunica intima: endothelium, subendothelial layer, and internal elastic membrane

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10
Q

what is the endothelium of the tunica intima

A

-simple squamous epithelium lines the lumen of all vessels
-continuous with the endocardium
-slick surface reduces friction (reduces friction between blood & walls)

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11
Q

what is the subendothelial layer of the tunica intima

A

-connective tissue basement membrane
-found only in vessels > 1mm

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12
Q

what is the internal elastic membrane of the tunica intima

A

elastic fibers in outer margin of arteries (divides tunica intima and media)

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13
Q

what is the tunica media

A

the middle layer is composed mostly of smooth muscle and sheets of elastin
-innervated by SYMPATHETIC VASOMOTOR NERVE FIBERS which controls:
vasoconstriction: decreased lumen diameter
vasodilation: increased lumen diameter
-bulkiest layer responsible for maintaining blood flow and BP
has the external elastic membrane

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14
Q

what are the sympathetic vasomotor nerve fibers responsible for

A

changes size of lumen, adjust diameter of lumen
-vasoconstriction: decreased lumen diameter
-vasodilation: increased lumen diameter

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15
Q

what is the external elastic membrane of the tunica media

A

it seperates the tunica media from the externa

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16
Q

what is the tunica externa (adventitia)

A

the outermost layer of the wall
-composed mostly of loose collagen fibers that protect and reinforce wall and anchor it to surrounding structures
-infiltrated with nerve fibers and lymphatic vessels
large veins also contain elastic fibers in this layer

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17
Q

describe vasa vasorum and its function

A

a system of tiny blood vessels found in larger vessels
-functions to nourish outermost external layer

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18
Q

what are the three types of vessels

A

arteries, capillaries, and veins

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19
Q

what are the three types of arteries

A
  1. elastic artery (conducting artery)
  2. muscular artery (distributing artery)
  3. arterioles
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20
Q

explain the elastic/ conducting arteries

A

thick-walled, low resistence lumen, lots of elastin in all tunics, have pressure resevoirs

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21
Q

explain the muscular/ distributing arteries

A

account for most arteries, thickest tunica media, less elastic, has a lot more smooth muscles (tunica media)

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22
Q

explain arterioles

A

smallest of the arteries, vasodilation and constriction-> blood flow into capillary beds resistance arteries

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23
Q

describe capillaries

A

-smallest vessels (microscopic networks), with thin walls
-single-walled; absence of tunica media and externa
-supply almost every cell, except for cartilage, epithelia, cornea, and lens of the eye

24
Q

what are the functions of the capillaries

A

exchange of gases, nutrients, wastes, hormones, etc., between blood nad interstitial fluid

25
Q

what are pericytes and where are they found

A

they are stem cells that stabilize capillary walls, control permeability, and vessel repair
they are found on capillaries

26
Q

why are capillaries single cell walled

A

due to an abscence of tunica media and externa

27
Q

what type of junctions do all capillaries have

A

all capillary endothelial cells are joined by tight junctions wuth gaps called intercellular clefts, which allow for passage of fluids and small solutes

28
Q

what are the three types of capillaries

A

continuous, fenestrated, and sinusoid capillaries

29
Q

describe the continuous capillaries

A

-the least permeable and most common
-abundant in SKIN, muscles, lungs, and CNS
-pinocytotic vesicles (bulk transport/ endocytosis “cell drinking”) ferry fluid across the endothelial cell
-most continuous capillaries have INTERCELLULAR CLEFTS BETWEEN ENDOTHELIAL CELLS. however brain capillary endothelial cells lack intercellular clefts and have tight junctions around thier entire perimeter

30
Q

describe fenestrated capillaries

A

-have large fenestrations (pores) that increase permeability
-occur in active areas of filtration (ex. kidney) or absorption (ex. intestines) and areas of endocrine hormone secrection
-fenestrations are swiss-cheese like holes that tunnel through enodthelial cells
-fenestrations are usually covered by a very thin layer of condensed extracellular glycoproteins. this layer has little effect on solute and fluid movement
-in some digestive tract organs, the number of fenestrations in capillaries increase during active absorption of nutrients

31
Q

describe sinusoid capillaries

A

-the most permeable and occur in limited locations
-occur in liver, bone marrow, spleen, and adrenal medulla
-have LARGE INTERCELLULAR CLEFTS as well as fenestrations
-have few gap junctions
-have an incomplete basement membrane
-are irregularly shaped and have larger lumens than other capillaries
-allow large molecules and even cells to pass across thier walls
-blood flows slowly through their walls
-macrophages may extend processes through the clefts to catch “prey” or in liver, form part of the sinusoid wall

32
Q

describe capillary beds

A

-interwoven network of capillaries between artioles and venules
-microcirculation: flow of blood through bed from arteriole to venule
-terminal arteriole: branch of atriole that further branches into 10-20 capillaries (exchange vessels) that form capillary beds
-capillaries then drain into postcapillary venule
-flow through bed controlled byy diameter of terminal arteriole and upstream arterioles

33
Q

what is microcirculation

A

flow of blood through bed from arteriole to venulea

34
Q

what is terminal arteriole

A

branch of arteriole that further branches into 10-20 capillaries (exchange vessels) that form capillary bed

35
Q

explain capillaries in serous membranes of intestinal mesentaries

A

they have two additional features that form a special arrangement of capillaries which are the 1. vascular shunt and 2. precapillary sphincter

36
Q

describe the vascular shunt

A

capillaries in serous membranes of intestinal mesentaries that channel directly connects arteriole with venule (bypasses true capillaries/ capillary bed)
-consists of metarteriole (micro vessels that link) and thoroughfare channel (connects metarteriole to venule)

37
Q

describe precapillary sphincters

A

capillaries in serous membranes of intestinal mesentaries that cuff off smooth muscle surrounding each true capillary that branches off mertarteriole
-acts as valve regulating blood flow into capillary bed
-controlled by local chemical conditions (not innervated)

38
Q

what are veins

A

-carry blood toward the heart; formed from convergence of venules

39
Q

describe venules

A

-capillaries unite to form postcapillary venules-» veins
-consists of endothelium and a few pericytes
-very porous; allow fluids and white blood cells into tissues
-larger venules have on or two layers of smooth muscle cells

40
Q

explain the tunica components of veins

A

-have all 3 tunics but thinner wall and larger lumens
-the tunica media is thin, but tunica externa is thick
-large lumen and thin walls make veins good storage vessels (called capacitance vessels/ blood reservoirs-> contain up to 65% of blood supply

41
Q

what is the distribution of blood in the cardiovascular system

A

-pulmonary vessels= 9%
-heart= 7%
-systemic arteries and arterioles= 13%
-systemic capillaries= 7%
-systemic veins and venules (blood reservoirs)= 64%

42
Q

what are systemic veins

A

-supply all of the body except the lungs
-are distensible (able to stretch and expand)
-contain a large proportion of blood volume and so are called capacitance vessles or blood reservoirs

43
Q

explain the three types of veins

A
  1. Large vein
  2. medium-sixed vein
  3. venule
44
Q

why are there venous adaptations

A

since blood pressure is in the veins there has to be adaptations to ensure return of blood to the heart

45
Q

what are the three types of venous adaptations

A
  1. large-diameter lumens
  2. venous valves
  3. venous sinuses
46
Q

describe how large-diameter lumens are a venous adaptation

A

this offers little resistence

47
Q

describe how venous valves are a venous adaptation

A

they are fold of tunica intima
-they prevent backflow of blood
-most abundant in veins of limbs
-compression pushes blood toward heart

48
Q

describe how venous sinuses are a venous adaptation

A

they are flattened veins with extremely thin walls
-composed of only endothelium
ex. coronary sinus of the heart and dural sinuses of the brain

49
Q

what is angiogenesis

A

formation of new blood vessels from preexisting ones
-promoted by pro-angiogenic factos (proteins)= VEGF, FGF, EGF, PDGF, HGF, TGF
-inhibitied by antiangiogenic factors (proteins)= angiostatin, endostatin, thrombospondins, interferons, vasostatin
-implicated in several conditions: tumorgenesis, diabetic retinopathy, age-related blindness, skin diseasem CVDs, stroke, etc.

50
Q

what are the proteins that promote angiogenesis

A

-VEGF= vascular endothelial growth factor
-FGF= fibroblast growth factor
-EGF= epidermal growth factor
-PDGF= platelet derived growth factor
-HGF= hepatocyte growth facotr
-TGF= transformin growth factor

51
Q

what is angiogenesis- based medicine

A

used in the prevention of blood vessel formation-> inhibit diseases

52
Q

what are varicose veins and how do they form

A

-abnormally twisted and enlarged veins
-due to weakening of valves-> incompetent vein valves
-most significant in limbs rather than upper parts of body (neck, head)

53
Q

what is arteriosclerosis

A

arterial walls become thickened

54
Q

what is atherosclerosis

A

formation of plaque (fatty deposits) within tunica media

55
Q

what is focal calcification

A

deposition of calcium salts
smooth muscle cells within tunica media eroded

BIOL 112 (21 decks)

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