EXAM 2 Starts: Circulatory System Flashcards
1
Q
what is the primary function of the circulatory system
A
transport of O2, CO2 and nutrients/ metabolic waste
2
Q
what are the secondary functions of the circulatory system
A
thermoregulation, transport of immune cells/hormones
3
Q
what does the blood vascular system consist of
A
heart and blood vessels
4
Q
what are the two components of the circulatory system
A
pulmonary circulation and systemic circulation
5
Q
what is pulmonary circulation
A
RA -> RV ->pulmonary artery -> lungs -> pulmonary veins -> LA
6
Q
what is the systemic circulation
A
LA -> LV -> aorta -> rest of body
7
Q
what is the lymph vascular system
A
passive drainage system for returning extravascular fluid (lymph) to blood vascular system
8
Q
what does the lymph vascular system rely on and why
A
muscle contractions and body movement because it lacks an intrinsic pump
9
Q
what are vascular tunics
A
blood vessels of the circulatory system have common basic structure with 3 concentric layers
10
Q
what are the 3 vascular tunics from innermost to outermost
A
- tunia intimia
-tunica media - tunia adeventitia
11
Q
what is the tunica intima, what type of epithelia, and how thick
A
innermost layer of simple squamous endothelial cells lining the lumen. very thin 1-2 cells thick
12
Q
what is the function of the tunica intima
A
forms a semi-permeable barrier supported by the basement membrane
13
Q
what are the tight junctions between endothelial cells in the tunica intima called
A
fascia occludens
14
Q
what supports the tunica intima
A
subendothelial connective tissue
15
Q
where is the internal elastic lamina
A
separates the tunica intima from the tunica media
16
Q
what is the internal elastic lamina made of
A
elastic fibers arranged in an sin wave pattern
17
Q
what is the tunica media
A
middle layer made of smooth muscle and fibroblastic connective tissue
18
Q
what is the thickest layer in arteries and what do arteries contain
A
tunica media
- may contain reticulin (type 3 collagen) and elastic fibers
19
Q
where is the external elastic lamina located
A
between tunica media and adventitia
20
Q
what is the external elastic lamina composed of
A
elastic fibers but less organized than internal elastic lamina
21
Q
what is the tunica adventitia and what does it contain
A
outermost layer made of loose fibroblastic CT, fibroblasts, collagen, elastic fibers and smooth muscle cells
22
Q
what is the thinner layer in the arteries
A
tunica adventitia
23
Q
what is the thickest layer in veins
A
tunica adventitia
24
Q
what are vasa vasorum and where are they located
A
they are small blood vessels that supply the tunica media and adventitia in both large arteries and veins
25
what are nervi vasculares and where are they found
autonomic nerves that control smooth muscle contraction in vessel walls in the tunica media
26
what is vasoconstriction due to
action of sympathetic, post-ganglionic nerve fibers
27
what happens in vasoconstriction
acts on smooth muscle of tunica media to cause vasoconstriction and decrease lumen diameter
28
what are the different mechanisms of vasodilation
- passive; occurs in absence or inhibition of sympathetic stimulation
-accomplished via indirect parasympathetic innervation (Ach causes endothelial cells to release NO which causes smooth muscle cells to relax
- in response to low O2 tension, smooth muscle in walls of arterioles relaxes
29
where are baroreceptors and chemoreceptors found
in walls of blood vessels
30
what do baroreceptors do and where are they located
detect BP located in carotid sinus and aortic arch
31
what do chemoreceptors do and where are they located
they detect changes in O2, CO2, tension and pH and are located at bifurcation of carotid arteries and in aortic bodies in aortic arch
32
what are the functions of the arterial system
-conducts blood away from heart to capillary bed
- venous system returns blood from capillaries to heart
33
what is pulsatile blood flow
cyclical pumping of heart
34
what is systole
contraction of ventricles
35
what is diastole
decrease in pressure
36
what do the expansion and recoil of elastic arteries do
maintain BP
37
what controls the diameter of blood vessels
sympathetic control of smooth muscle in vessel walls
38
what do arteries contain and describe their wall
large amounts of elastin and smooth muscle, thick wall relative to lumen diameter
39
describe elastic arteries and give examples
-large, conducting vessels that receive blood directly from the heart (ex:aorta, common carotid, subclavian, pulmonary artery)
- sheets of elastic tissue in tunica media to maintain BP
-thickest layer
40
what layers do elastic arteries have
tunica intima, media, and adventitia and internal and external elastic lamina
41
describe muscular arteries
medium sized
- have more smooth muscle and less elastin in tunica media than elastic arteries
42
what layers do muscular arteries have and what layer is the thickest
tunica media, intima, and adventitia and distinct internal elastic lamina. larger muscular arteries may also contain external elastic lamina
- thickest: tunica media
43
describe arterioles
-smallest
- little smooth muscle
-elastic laminae are absent
44
what are arterioles
terminal branches of arterial system that supply capillary beds
- major sites of vasoconstriction and vasodilation
45
what is the function of arterioles
regulate distribution of blood to capillaries via pre-capillary sphincters
46
how do arterioles regulate distribution of blood to capillaries
pre-capillary sphincters
47
what are pre-capillary sphincters
intermittent rings of smooth muscle within walls of arterioles
48
what are metarterioles
small diameter arterioles; intermediate in size between arterioles and capillaries
49
what are metarterioles characterized by
discontinuous layer of smooth muscle in tunica media
50
what accompanies an increased amount of smooth muscle
increased diameter of vessel and decreased amount of CT
51
what does microcirculation do
exchange of gases, fluids, nutrients, metabolites, and waste products
52
where does microcirculation occur
within capillaries but also includes arterioles and venules
53
what are capillaries
thin walled vessels 8-10 micrometers in diameter
54
what are capillaries lined with
a thin single layer of endothelial cells supported by basal lamina and small number of pericytes
55
what are pericytes
contractile, precursor for endothelial cells and can become smooth muscle cells
56
what are pericytes derived from
the same precursor as endothelial cells
57
what do capillaries lack
tunica adventitia (no outer CT layer), tunica media (no smooth muscle)
58
how do vasodilation and vasoconstriction occur in capillaries
smooth muscle contraction in arterioles and pre-capillary sphincters which result in passive changes in capillary diameter
59
what are continuous capillaries and where are they found
endothelium forms continuous lining. found in muscle, lung CNS
60
what are fenestrated capillaries and where are they found
endothelial cells possess pores or fenestrae within cells. found in endocrine glands and GI tract
61
what are discontinuous capillaries and where are they found
basal lamina not continuous; endothelial cells separated by large gaps between cells. can form sinusoids. found in liver, spleen, bone marrow
62
how does transport across capillaries occur
via fenestrae, transcytosis or diapedesis
63
what does the venous system function as
low pressure collecting systtem returning blood from capillary beds to the heart
64
describe veins
thinner walled vessels with larger lumen than arteries
65
describe the tunica media in veins compared to arteries
fewer layers of smooth muscle in tunica media than arteries
66
what is the thickest tunic in veins
tunica adventitia
67
where are valves located and what do they do
in veins they prevent backflow, especially in limbs and thorax
68
what are varicose veins
valve failure in legs
69
what are venules and describe them
small veins, lack elastic laminae and smaller venules may lack tunica media
70
what are post capillary venules and where are they located
located after capillaries and tunica media and adventitia are reduced or absent
71
what do post capillary venules do
-site for diapedesis
- drain into large collecting venules then muscular venules
72
describe muscular venules
thin smooth muscle layer in tunica media, thicker tunia adventitia
73
what are examples of vasoactive substances and what do they do
histamine or serotonin and they act on venules to enlarge intercellular spaces and increase the permeability of the vessel
74
what are muscular veins
large and medium sized veins
75
describe small muscular veins
may or may not contain internal elastic laminal and does not have external elastic lamina
76
describe medium muscular veins
contain internal elastic lamina only
77
describe large muscular veins
contain internal and external elastic laminae
78
what controls the lumen diameter of muscular veins and venules
smooth muscle in tunica media
79
what do AV shunts do
direct connections between arterial and venous system to bypass a capillary bed
80
what are AV shunts and where are they located
type of anastomosis; common in skin, function in thermoregulation
81
what are portal vessels and give examples
vein or artery directly connecting two capillary beds
ex: hepatic portal vein, venous portal system
82
what is atherosclerosis
when endothelium of vessel damaged, cholesterol adheres to exposed proteins
83
what are the steps in atherosclerosis
-when endothelium of vessel is damaged, cholesterol adheres to exposed proteins
- once endothelium heals, cholesterol patch reabsorbed
- phagocytosis by macrophages and later by foam cells
- if inflammatory response becomes chronic -> atherosclerosis and plaque formation
84
what are foam cells
endothelial and subintimal cells
85
what is atherosclerosis later accompanied by
smooth muscle cells and formation of fibrous CT capsule
86
what happens when cells within the atherosclerotic plaque die
necrosis and calcification
87
why is atherosclerosis often associated with hypertension
from decrease in lumen diameter and increase in systolic BP
88
what is the most common cause of ischemic heart disease
atherosclerosis
89
what happens with coronary artery in ischemic heart disease
coronary artery lumen may be decreased by 90%
90
what is stenosis
gradual narrowing by plaque
91
what is thrombosis
occlusion of vessel
92
what happens as plaque enlarges or if endothelium is damaged in atherosclerosis
underlying collagen is exposed
93
what is the series of events of atherosclerosis
-plaque formation
- initiates clotting cascade which forms a thrombus
- if a piece of thrombus breaks off it becomes an embolus
- occlusion by an embolus is an acute ischemic event
94
what does sudden occlusion of an artery cause
decrease in O2 to the heart and thus chest pain
95
what happens in myocardial infarction
portion of muscle dies in heart as a result of occlusion
96
how does healing occur in the heart
fibrosis
97
why does the repair of heart muscle after ischemic attack still result in decreased or partial loss of function
because CT is less contractile than muscle
98
what is endocarditis
inflammation and thickening of AV valves often associated with valvular incompetence
99
what is valvular incompetence
increased turbulence, regurgitation which results in vegetative endocarditis and thromboembolic disease
100
what is a stroke
blood clot in the brain
101
what does a cerebral infarct result in
cell death and loss of function
102
what determines the symptoms and severity of a stroke
the location of the clot
103
what are aneurisms
blood vessels dilate to form thin-walled, balloon like regions that commonly burst
104
where are aneurisms common
aorta or brain
105
describe the lymph vascular system
structurally similar to veins, but endothelial cells are thinner and have greater permeability
- thin tunica media
- valves present
- BM and pericytes may or may not be present
106
what do lymph endothelial cells do
active in phagocytosis
107
what is the function of the lymph vascular system
drain excess fluid from ECS and return it to the blood stream
108
what is lymph formed as a result of
high hydrostatic pressure in arterioles;exceeds colloidal oncotic pressure exterted by plasma proteins which results in the leakage of water, electrolytes, and plasma proteins from capillaries into ECS
109
what is lymph high in
proteins
110
where do lymphatic vessels converge
thoracic duct and right lymphatic ducts
111
where does lymph return to the bloodstream
at the junction of the left internal jugular vein and left subclavian vein
112
how is lymph moved
skeletal muscle contraction and body movement
113
what can immobility lead to
peripheral edema
114
where are lymph nodes located
interspersed along lymph vessels
115
what tunics do lymph vessels contain
tunica media
116
what do lymph nodes contain
lymphoid tissue for antigenic sampling and recognition, activation of immune cells and production of anitbodies
117
how do tumors metastasize
asymmetrical lymph drainage
118
how do you identify lymph vessels
thin walled, lack blood, contain smooth eosinophilic, proteinaceous fluid, occasional WBCs
119
what happens in elephantiasis
pericytes set up in lymphatics to restrict lymph flow from peripheral tissues
