1
Q
Pumps and directs the blood cells and substances carried in blood to all tissues of the body
A
Circulatory system
2
Q
Circulatory system includes both?
A
blood and lymphatic system
3
Q
range of circulatory system in adult
A
100,000 - 150,000 km
4
Q
propels blood through the system.
A
heart
5
Q
it is a series of vessels efferent from the heart that become smaller as they branch into the various organs
A
arteries
6
Q
- carry blood to the tissues.
A
arteries
7
Q
the smallest vessels
A
Capillaries
8
Q
are the sites of Oxygen, Carbon dioxide, nutrient, and waste product exchange between blood and tissues.
A
Capillaries
9
Q
result from the convergence of venules into a system of larger channels which continue enlarging as they approach the heart
A
veins
10
Q
where blood is oxygenated in the lungs
A
Pulmonary Circulation
11
Q
where blood brings nutrients and removes wastes in tissues throughout the body
A
Systemic Circulation
12
Q
three major layers of the heart
A
- endocardium
- myocardium
- epicardium
13
Q
thin inner layer
A
Endocardium
14
Q
Surrounding modified cardiac muscle fibers → heart’s impulse conducting system
A
Endocardium
15
Q
deeper layer of connective tissue beneath the endocardium
A
subendocardial layer
16
Q
(muscular middle layer)
A
Myocardium
17
Q
Mainly contractile cardiac muscle fibers arranged spirally
A
Myocardium
18
Q
what part of the heart has a thicker myocardium, it needs strong force to pump blood
A
left ventricles
19
Q
(outer protective layer)
A
Epicardium
20
Q
Corresponds to visceral layer of pericardium
A
Epicardium
21
Q
Reflected back as parietal layer at large vessels
A
Epicardium
22
Q
specific subtype of epicardium
A
Simple squamous mesothelium with loose connective tissue (blood vessels and nerves)
23
Q
this cushions structures
A
adipose tissue
24
Q
it prevents friction
A
lubricant fluid
25
Dense irregular connective tissue separating atria from ventricles
cardiac skeleton
26
The heart’s fibrous skeleton supports and anchors the valves
Cardiac Skeleton
27
Provides attachment for cardiac muscle
cardiac skeleton
28
Acts as electrical insulation to coordinate the heartbeat.
cardiac skeleton
29
2 Conducting system of the heart
1. SA node
2. AV node
30
Specialized myocardial tissue in right atrial wall near superior vena cava; less well-stained cardiac muscle cells with fewer myofibrils and intercalated disks.
SA node (pacemaker)
31
Specialized myocardial tissue in right atrial wall; gives rise to the AV bundle (bundle of His).
AV node
32
Subendocardial conducting network of cardiac muscle fibers usually called?
Purkinje Fibers
33
Pale-staining fibers, larger than adjacent contractile fibers, with sparse peripheral myofibrils and much glycogen
Purkinje Fibers
34
it mingle distally with contractile muscle fibers of each ventricle and trigger waves of contraction through both ventricles simultaneously
Purkinje Fibers
35
this innervate the heart
Parasympathetic and sympathetic neural components
36
The walls of all blood vessels, except capillaries, have smooth muscle and connective tissue along with an?
endothelial lining
37
activity of tissues of the vascular wall is affected by?
mechanical and metabolic factors
38
A specialized epithelium that acts as a semipermeable barrier between blood and tissue fluid.
Endothelium
39
Made of squamous, polygonal, and elongated cells aligned with blood flow.
Endothelium
40
Endothelium controls two-way exchange of molecules through?
diffusion, endocytosis, and transcytosis.
41
The endothelium prevents blood clotting and releases substances that control local clot formation.
Nonthrombogenic Surface
42
it release factors that cause smooth muscles to contract or relax, helping regulate blood flow.
Endothelial cells
43
it helps white blood cells stop and pass through vessel walls at injury or infection sites.
endothelium
44
___________ from Weibel-Palade bodies helps white blood cells stick to the endothelium, and ________ are released to control their activity in that area.
P- selectin, interleukins
45
Endothelial cells secrete ________ promoting proliferation of white blood cell lineages and vascular wall cells
proteins
46
Promotes blood vessel formation in embryos, maintains vessels in adults, and supports new vessel growth during repair, regeneration, and tumor formation.
VEGF (vascular endothelial growth factor)
47
Stimulate endothelial cells to recruit smooth muscle cells and fibroblasts to form other tissues of the vascular wall
Angiopoietins
48
this occur in the walls of all vessels larger than capillaries and are arranged helically, in layers.
Smooth muscle fibers
49
in ________, the smooth muscle cells are connected by many more gap junctions and permit vasoconstriction and vasodilation that are the key importance in regulating the overall blood pressure.
ARTERIOLES AND SMALL ARTERIES
50
this are present in vascular walls in variable amounts and proportions based on local functional requirement.
Connective tissue components
51
are found in the subendothelial layer, between the smooth muscle layers, and in the outer covering.
Collagen fibers
52
it provide the resiliency required for the vascular wall to expand under pressure.
Elastic fibers
53
All of these larger vessels have walls with three concentric layers, or tunics:
1. tunica intima
2. tunica media
3. tunica adventitia
54
innermost layer: endothelium + subendothelial connective tissue.
Tunica intima
55
middle layer: smooth muscle + elastic fibers.
Tunica media
56
outermost layer: connective tissue with collagen and elastic fibers.
Tunica adventitia (externa)
57
consists of the endothelium and a thin subendothelial layer of loose connective tissue sometimes containing smooth muscle fibers.
Tunica intima
58
In arteries the intima includes a thin layer, the __________, composed of elastin, with holes allowing better diffusion of substances from blood deeper into the wall.
internal elastic lamina
59
the middle layer, consists chiefly of concentric layers of helically arranged smooth muscle cells alternating with layers of elastic lamellae, reticular fibers, and proteoglycans.
tunica media
60
In larger arteries the media may also have an ________ separating it from the adventitia.
external elastic lamina
61
is connective tissue consisting principally of type I collagen and elastic fibers.
outer adventitia, or tunica externa
62
The adventitia is continuous with and bound to the ____ of the organ through which the blood vessel runs
stroma
63
Large vessels usually have _________ (“vessels of the vessel”).
vasa vasorum
64
are the aorta, the pulmonary artery, and their largest branches
Elastic arteries
65
these large vessels are also called _________ because their major role is to carry blood to smaller arteries.
conducting arteries
66
The key feature of elastic arteries is the thick _________ in which elastic lamellae alternate with layers of smooth muscle fibers.
tunica media
67
are slight dilations of the bilateral internal carotid arteries where they branch from the (elastic) common carotid arteries
Carotid sinuses
68
they act as **important baroreceptors** monitoring arterial blood pressure
Carotid sinuses
69
Located in the walls of the carotid sinuses and aortic arch are complex __________ which monitors blood CO₂ and O₂ levels, as well as its pH
chemoreceptors
70
These structures are parts of the autonomic nervous system called _______ with rich capillary networks
paraganglia
71
are closely surrounded by large, neural crest-derived glomus cells filled with dense-core vesicles containing dopamine, acetylcholine, and other neurotransmitters
capillaries
72
Ion channels in the glomus cell membranes respond to stimuli in the arterial blood, primarily hypoxia (low O₂), hypercapnia (excess CO₂), or acidosis, by activating release of ??????
neurotransmitters
73
_______ branching from the glossopharyngeal nerve form synapses with the glomus cells and signal brain centers to initiate cardiovascular and respiratory adjustments that correct the condition
Sensory fibers
74
this distribute blood to the organs and help regulate blood pressure by contracting or relaxing the smooth muscle in the media.
muscular arteries (distributing arteries)
75
it has a thin subendothelial layer and a prominent internal elastic lamina. The media may contain up to 40 layers of large smooth muscle cells
intima
76
branch repeatedly into smaller and smaller arteries, until reaching a size with three or four layers of medial smooth muscle.
Muscular arteries
77
The smallest arteries branch as _______, which have only one or two smooth muscle layers.
arterioles
78
conduct blood from heart and with elastic recoil help move blood forward under steady pressure
elastic arteries
79
distribute blood to all organs and maintain steady blood pressure and flow with vasodilation and constriction
muscular arteries
80
distribute blood to arterioles adjusting flow with vasodilation and constriction
small arteries
81
resist and control blood flow to capillaries; major determinant of systemic blood pressure
arterioles
82
exchange metabolites by diffusion to and from cells
capillaries
83
(postcapillary, collecting, and muscular) drain capillary beds; site of leukocyte exit from vasculature
venules
84
collect blood from venules
small veins
85
carrry blood to larger veins, with no backflow
medium veins
86
return blood to heart
large veins
87
The smallest arteries branch as ________, which have only one or two smooth muscle layers; these indicate the **beginning of an organ’s microvasculature** where exchanges between blood and tissue fluid occur.
arterioles
88
In almost every organ, _______ takes place between blood and the interstitial fluid of the surrounding tissues.
molecular exchange
89
But not all ________ formed at capillary beds is drained into venules
interstitial fluid
90
the excess is called ______ and collects in thin walled, irregularly shaped lymphatic vessels.
lymph
91
is where arterioles deviate from this simple path to accommodate various specialized functions in certain organs and are richly innervated by sympathetic and parasympathetic nerve fibers.
Arteriovenous shunts (or arteriovenous anastomoses)
92
control the degree of vasoconstriction at the shunts, regulating blood flow through the capillary beds.
autonomic fibers
93
high capillary blood flow in the skin allows more _________ from the body
heat dissipation
94
while reduced capillary blood flow
conserves heat
95
is where blood flows through two successive capillary beds separated by a portal vein.
Portal system
96
This arrangement allows for hormones or nutrients picked up by the blood in the first capillary network to be delivered most efficiently to cells around the second capillary bed before the blood is returned to the heart for general distribution.
Microvascular Pathways
97
it permit and regulate metabolic exchange between blood and surrounding tissues
Capillaries
98
These smallest blood vessels always function in networks called????
capillary beds
99
are composed of the simple layer of endothelial cells rolled up as a tube surrounded by basement membrane.
Capillaries
100
Capillary beds are supplied preferentially by one or more terminal arteriole branches called?
metarterioles.
101
The metarteriole muscle cells act as ___________ that control blood flow into the capillaries
precapillary sphincters
102
These precapillary sphincters contract and relax cyclically, with_________, causing blood to pass through.
5-10 cycles per minute
103
When the sphincters are closed, blood flows directly from the ______ and thoroughfare channels into _________
metarterioles, postcapillary venules.
104
have many features specialized for molecular transfer by mechanisms ranging from simple diffusion to transcytosis.
Capillary cells
105
The average thickness of the capillary cells is only ____ and their nuclei are often distinctively curved to accommodate the very small tubular structure.
0.25 μm
106
Capillaries are generally grouped into three histologic types:
1. Continuous capillaries
2. Fenestrated capillaries
3. Discontinuous capillaries (sinusoids)
107
many tight, well-developed occluding junctions between slightly overlapping endothelial cells. This is the most common type of capillary and is found in muscle, connective tissue, lungs, exocrine glands, and nervous tissue.
Continuous capillaries
108
have a sieve like structure that allows more extensive molecular exchange across the endothelium. Found in organs with rapid interchange of substances between tissues and the blood, such as the kidneys, intestine, choroid plexus, and endocrine glands.
Fenestrated capillaries
109
permit maximal exchange of macromolecules as well as allow easier movement of cells between tissues and blood. The endothelium here has large perforations without diaphragms and irregular intercellular clefts. This type are found in the liver, spleen, some endocrine organs, and bone marrow.
Discontinuous capillaries (sinusoids)
110
At various locations along continuous capillaries and postcapillary venules are mesenchymal cells called _________, with long cytoplasmic processes partly surrounding the endothelial layer.
pericytes
111
they secrete many ECM components and form their own basal lamina, which fuses with the basement membrane of the endothelial cells.
pericytes
112
Within the ____, pericytes are important for maintaining the endothelial blood-brain barrier. After injuries, pericytes proliferate and differentiate to form smooth muscle and other cells in new vessels as the microvasculature is reestablished.
CNS
113
are blood vessels that carry blood back to the heart. They usually travel alongside arteries but have thinner walls and larger lumens.
veins
114
Veins return blood to the heart under?
low pressure
115
The wall of veins is thinner than arteries and divided into three tunics:
1. Tunica intima
2. Tunica media
3. Tunica adventitia
116
Thin endothelium, may form valves.
Tunica intima
117
Thin layer of smooth muscle and elastic fibers.
Tunica media
118
Thick outer layer with collagen and elastic tissue.
Tunica adventitia
119
Have relatively large lumens compared to small arteries.
- The wall is very thin, containing only 2–3 layers of smooth muscle.
Small Veins
120
in small veins what is thicker than the media
adventitia
121
- More developed than small veins.
- Have valves made from folds of the tunica intima.
- The media and adventitia are both more distinct.
- Found in limbs where they prevent blood backflow.
MEDIUM Veins
122
- Formed by paired folds of tunica intima lined with endothelium.
- Reinforced by elastic fibers.
- Function: Prevent backflow of blood, especially in lower limbs.
- Important in maintaining venous return to the heart
Vein Valves
123
- Occur when valves weaken or fail, causing blood pooling.
- Vein walls become distended and tortuous.
- Common in legs due to gravity and prolonged standing.
Varicose Veins
124
A network of thin-walled vessels that collects excess interstitial fluid (lymph) from tissues and returns it to blood circulation.
Lymphatic Vascular system
125
Closely linked with immune defense, nutrient absorption, and tissue fluid balance.
Lymphatic Vascular system
126
Structures of Lymphatic vascular System
1. Lymphatic Capillaries
2. Lymphatic Vessels
3. Lymphatic Ducts
4. Lymph
127
collect excess interstitial fluid from the tissue spaces as lymph and return it to the blood.
Lymphatic Capillaries
128
- Formed by convergence of capillaries.
- Walls: thin, with smooth muscle + connective tissue (but not well-defined tunics).
Lymphatic Vessels
129
- Have valves (like veins) made of intimal folds → keep flow unidirectional.
- Lymph nodes interposed along pathway → immune filtration.
- Flow assisted by skeletal muscle contraction & external pressure.
Lymphatic Vessels
130
two ducts of lymphatic ducts
1. Thoracic duct
2. Right lymphatic duct
131
drains most of body
Thoracic duct
132
thoracic duct - Enters venous system at junction of?
left internal jugular vein + left subclavian vein
133
- drains right upper body
- Structure similar to small veins, but adventitia underdeveloped
Right lymphatic duct
134
Right lymphatic duct- Enters venous system at junction of ?
right internal jugular vein + right subclavian vein
135
- Clear, protein-rich fluid
- Normally no RBCs
- Contains lymphocytes & WBCs
- Acts as a transport medium for immune components
lymph
136
Returns interstitial fluid & plasma proteins to blood
Lymphatic System
137
Lymphatic System is the major pathway for?
lymphocytes & antibodies
138
- Supports immune defense → lymph filtered in nodes
- Distributes immune cells through organs & tissues
Lymphatic System
139
are generally less than 0.1 mm in diameter, with lumens approximately as wide as the wall is thick.
arterioles
140
it is very thin, elastic laminae are absent, and the media consists of the circularly arranged smooth muscle cells.
subendothelial layer
141
In both small arteries and arterioles the _______ is very thin and inconspicuous.
adventitia
142
Arterioles almost always branch to form anastomosing networks of ______ that
surround the parenchymal cells of the organ.
capillaries
143
At the ends of arterioles the ________ act as sphincters and produce periodic blood flow into capillaries.
smooth muscle fibers
144
it normally keeps arterioles partially closed, resisting blood flow, which makes these vessels the major determinants of systemic blood pressure.
Muscle tone
145
they are similar to capillaries with pericytes but larger, ranging in diameter from 15 to 20 um
Postcapillary venules
146
the primary site at which white blood cells adhere to endothelium and leave the circulation at sites of infection or tissue damage.
Postcapillary venules
147
With increasing size venules become surrounded by a recognizable tunica media with two or three smooth muscle layers and are called?
muscular venules.
148
A characteristic feature of all venules is the large diameter of the ______ compared to the overall thinness of the wall.
lumen
Histology
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