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HSF > HSF 2 - Unit 1 Histology: Circulatory System > Flashcards

HSF 2 - Unit 1 Histology: Circulatory System Flashcards

1
Q

what is the primary function of the circulatory system?

A

transport of O2/CO2 and nutrients/metabolic waste

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2
Q

what are the secondary functions of the circulatory system?

A

thermoregulation, transport of immune cells/hormones

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3
Q

what does the vascular system consist of?

A

heart and blood vessels (=blood vascular system)

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4
Q

what are the 2 components of the circulatory system?

A

pulmonary circulation and systemic circulation

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5
Q

what is the course of pulmonary circulation?

A

RA and RV - pulmonary arteries - lungs - pulmonary veins - LA

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6
Q

what is the course of systemic circulation?

A

LA and LV - aorta - rest of body

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7
Q

what is the lymph vascular system?

A

passive drainage system for returning extravascular fluid (lymph) to blood vascular system; lacks intrinsic pump, relies on muscle contraction, body movement

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8
Q

what are the layers of blood vessels?

A

tunics, have common basic structure with concentric layers

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9
Q

what is the innermost layer of blood vessels?

A

tunica intima; simple squamous endothelial cells lining the lumen, 1-2 cells thick; forms a semi-permeable barrier supported by the basement; specialized discontinuous tight junctions between endothelial cells called fascia occludens, variable amounts of subendothelial connective tissue

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10
Q

what is the internal elastic lamina?

A

separates the tunica intima and tunica media, composed of elastic fibers

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11
Q

what is the tunica media?

A

highly variable middle layer of blood vessels; smooth muscle cells and fibroblastic connective tissue; in arteries it is the thickest layers and may also contain reticulin (type III collagen) and elastic fibers

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12
Q

what is the external elastic lamina?

A

located between tunica media and adventitia, also composed of elastic fibers, but less organized than internal elastic lamina

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13
Q

what is the tunica adventitia?

A

outermost layer in blood vessels, consists of loose fibroblastic CT- fibroblasts, collagen and elastic fibers, smooth muscle cells; thinner in arteries, in veins is the thickest layer and contains the vasa vasorum and autonomic nerves called nervi vasculares

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14
Q

what is the vasa vasorum?

A

small blood vessels that supply the tunica media and adventitia in both large arteries and veins

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15
Q

what are nervi vasculares?

A

control smooth muscle contraction in vessel walls (vasoconstriction and vasodilation)

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16
Q

what is vasoconstriction?

A

contraction of the smooth muscles in the tunica media of the blood vessels due to action of sympathatic, post-ganglionic nerve fibers; overall cause decrease in lumen diameter

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17
Q

what is vasodilation?

A

passive, occurs in absence or inhibition of sympathetic stimulation, accomplished via indirect parasympathetic innervation (Ach causes endothelial cells to release nitrous oxide NO, which secondarily causes smooth muscle cells to relax), in response to low O2 tension, smooth muscle in walls of arterioles relaxes and results in vasodilation and increase in blood flow

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18
Q

what are baroreceptors?

A

located in carotid sinus and aortic arch, detect blood pressure

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19
Q

what are chemoreceptors?

A

located at bifurcation of carotid artery and in aortic bodies in aortic arch, detect changes in O2, CO2 tension and pH

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20
Q

what are the specialized sensory receptors in walls of blood vessels?

A

baroreceptors and chemoreceptors

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21
Q

the arterial system conducts blood _____ _____ the heart, ____ _____ capillary bed

A

away from, to the

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22
Q

the venous system ______ blood from _______ to ______.

A

returns, capillaries, heart

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23
Q

what is pulsatile blood flow due to?

A

cyclical pumping of heart

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24
Q

what is systole?

A

contraction of the ventricles, pressure wave

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25
Q

what is diastole?

A

relaxation of heart, decreases pressure

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26
Q

what is normal blood pressure?

A

120/88 mmHg

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27
Q

how do arteries maintain blood pressure?

A

expansion and recoil of elastic arteries

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28
Q

how do sympathetic nerves control contraction and blood pressure?

A

via smooth muscle, controls via changes in diameter of the blood vessels

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29
Q

arteries contain large amounts of ______ and ______; …

A

elastin and smooth muscle, vessel wall thick relative to lumen diameter

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30
Q

what are the special characteristics of elastic arteries? what are some examples?

A

large conducting vessels, receive blood directly from the heart, have sheets of elastic tissue in the tunica media (thickest layer) to help maintain bp in between systole and diastole, possess both internal and external elastic laminae; aorta, common carotid, subclavian, pulmonary arteries

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31
Q

what are the special characteristics of muscular arteries?

A

medium sized distributing arteries, 2-10 mm in diameter; have more smooth muscle and less elastin in tunica media than elastic arteries; tunica media is the thickest layer; there is a distinct internal elastic lamina, larger muscular arteries may also contain external elastic lamina

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32
Q

what are arterioles? what are their characteristics?

A

terminal branches of the arterial system, supply the capillary beds; 10-100 micrometers in diameter, contain relatively little smooth muscle (tunica media is only 2-3 cells thick) ; elastic lamina is absent, major sites of vasoconstriction and vasodilation to regulate the distribution of blood to capillaries via pre-capillary sphincters, intermittent rings of smooth muscle within walls of arterioles

33
Q

what are metarterioles?

A

small diameter arterioles; intermediate in size between arterioles and capillaries; characterized by discontinuous layer of smooth muscle in the tunica media

34
Q

what is the general rule of thumb regarding smooth muscle amount in relation to the diameter of the vessel?

A

amount of smooth muscle increases with increasing diameter of vessel (and relative amount of CT decreases)

35
Q

what is microcirculation?

A

concerned with exchange of gases, fluids, nutrients, metabolites, and waste products; occurs primarily in capillaries, but also includes arterioles and venules

36
Q

what are capillaries?

A

thin-walled vessels, 8-10 micrometers in diameter that are lined by thin, single layer of endothelial cells, supported by basal lamina and small numbers of pericytes

37
Q

what are pericytes derived from?

A

the same precursor cell as endothelial cells that can differentiate into endothelial cells or smooth muscle cells following injury

38
Q

capillaries lack …

A

outer CT layer / tunica adventitia, and also smooth muscle / tunica media, only possess tunica intima

39
Q

capillaries do not exhibit …

A

vasomotor activity themselves

40
Q

how is vasodilation/constriction accomplished in capillaries?

A

via smooth muscle contraction in arterioles and pre-capillary sphincters,, passive change in capillary diameter

41
Q

what are the types of capillaries?

A

continuous, discontinuous, and fenestrated

42
Q

what are continuous capillaries?

A

endothelium forms continuous lining; most common (e.g. Mm, lung, CNS)

43
Q

what are fenestrated capillaries?

A

endothelial cells possess pores, or fenestrae within cells (e.g. endocrine glands, GI tract)

44
Q

what are discontinuous capillaries?

A

basal lamina not continuous; endothelial cells separated by large gaps between cells; may form sinuoids (large diameter capillaries around 30-40 micrometers in diameter) e.g.: liver, spleen, bone, marrow

45
Q

how does transport across capillaries occur?

A

via fenestrae, transcytosis, or diapedesis

46
Q

what is the venous system’s function?

A

low pressure collecting system for returning blood from capillary beds to the heart

47
Q

how are veins different than arteries?

A

thinner walled vessels with larger relative luminal diameter than corresponding arteries, fewer layers of smooth muscle in tunica media compared to similar sized arteries

48
Q

what is the thickest tunic in veins?

A

tunica adventitia

49
Q

what is a special characteristic of veins and why is it there?

A

valves: prevent backflow, especially in limbs and thorax; if they fail in the legs, varicose veins

50
Q

what are venules?

A

small veinsl lack laminae and smaller venules may lack tunica media

51
Q

what are post-capillary venules?

A

10-50 micrometers in diameter; both tunica media and adventitia absent or reduced, drain into larger collecting venules, then muscular venules

52
Q

what are muscular venules?

A

50-100 micrometers in diameter with thin smooth muscle layer in tunica media with a thicker tunica adventitia; medium and large sized veins considered muscular veins

53
Q

what are vasoactive substances?

A

act on venules (e.g. histamine, serotonine) to enlarge intercellular spaces and increase the permeability of the vessel

54
Q

small muscular veins may or may not contain…

A

internal elastic lamina

55
Q

medium muscular veins contain only…

A

internal elastic lamina

56
Q

large muscular veins contain…

A

internal and external elastic laminae

57
Q

what does the smooth muscle in tunica media control?

A

the luminal diameter of muscular veins and venules

58
Q

what are AV shunts?

A

direct connections between arterial and venous system; bypass capillary bed; type of anastomosis, common in skin and function in thermoregulation

59
Q

what are portal vessels?

A

vein or artery directly connecting two capillary beds (e.g. hepatic portal V, a venous portal system)

60
Q

what is atherosclerosis and what causes it? what can happen if it advances?

A

thickening in the tunica intima of blood vessels due to lipid deposits and formation of foam cells; can be generalized or focal (plaque), most common acquired abnormality of blood vessels; as the plaque enlarges, or if endothelium damaged, exposes underlying collagen which initiates the clotting cascade and a thrombus forms, if a piece of the thrombus breaks off, can get an embolus (thromboembolic disease). a fibrous, connective tissue capsule forms and smooth muscle cells proliferate. as cells within the plaque die, necrosis and secondary calcification/hardening of the arteries; this is often associated with hypertension due to smaller diameter of vessel lumen and higher systolic bp

61
Q

what is a foam cell?

A

intimal cells or macrophages filled with lipid

62
Q

what is ischemic heart disease and what is its cause?

A

gradual narrowing (stenosis) by plaque - thrombosis (occlusion) of vessel; sudden occlusion by embolus causes an acute ischemic event and decrease O2 to heart muscle causing angina (chest pain); most common cause is atherosclerosis

63
Q

what causes a myocardial infarction?

A

untreated portion of muscle in the heart dies, death by ischemia

64
Q

why can’t the heart fully recover from MI?

A

cardiac muscle cells are in Go, can’t regenerate so healing occurs via fibrosis, but this CT is less contractile than muscle so lose some function

65
Q

what is endocarditis?

A

inflammation and thickening of AV valves often associated with valvular incompetence, higher turbulence and regurgitation which can lead to vegetative endocarditis and thromboembolic disease

66
Q

what is a stroke?

A

similar to MI, except affects the brain instead of the heart, similar loss of function because neurons are also terminally differentiated, can result in cerebral infarct; location of clot determines symptoms and severity

67
Q

what is an aneurism?

A

blood vessels can also dilate to form thin-walled, balloon-like regions, called aneurisms; these occasionally burst, common in the aorta or brain

68
Q

how does the lymph vascular system differ from venous system?

A

structurally similar but endothelial cells thinner with greater permeability

69
Q

lymph endothelial cells are highly active in

A

phagocytosis

70
Q

lymph vascular system’s tunic characteristics? any special features?

A

very thin tunica media; valves present; basement membrane and pericytes may be present or absent

71
Q

what is the purpose of the lymph vascular system?

A

drain excess fluid (lymph) from ECS and return it to the bloodstream

72
Q

why is lymph formed?

A

as result of hydrostatic pressure in arterioles; excess colloidal oncotic pressure exerted by plasma proteins which results in a leakage of water, electrolytes, and plasma proteins from capillaries into ECS

73
Q

what is the ECS drained by (lymph)

A

series of interconnected, blind-ending tubules (lymphatics) that converge on the thoracic duct (and R lymphatic duct), these are the largest lymph vessels in the body

74
Q

what tunics are in the lymphatic system?

A

tunica media

75
Q

lymph returns to _______ at…

A

bloodstream; junction of L internal jugular V and L subclavian V

76
Q

lymphatic system lacks a…

A

central pumping mechanism which is a movement of lymph accomplished via skeletal muscle contraction, body movement; immobility may lead to peripheral edema, swollen feet

77
Q

what are lymph nodes?

A

interspersed along lymph vessels, contain lymphoid tissue for antigenic sampling and recognition, activation of immune cells and production of Ab

78
Q

what is important in tumor metastasis?

A

asymmetrical lymph drainage

79
Q

how can we identify lymph vessels in a section?

A

thin walled, lack blood, contain smooth, eosinophilic, proteinaceous fluid (lymph), occasional WBCs; basement membrane rudimentary or absent with or without pericytes

HSF (23 decks)

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