BLOOD VESSEL LECTURE Flashcards
1
Q
Describe the circulatory routes of the blood vessels from largest to smallest.
A
the circulatory route travels through the heart –> arteries –> arterioles –> capillaries –> venules –> veins –> back to the heart
2
Q
What are portal systems?
A
portal systems allow blood to flow through two consecutive capillary networks before returning to the heart
3
Q
What is an anastomosis?
A
an anastomosis is a connection between two vessels
4
Q
What is an arteriovenous anastomosis (shunt)?
A
arteriovenous anastomosis is when blood flows from an artery directly into a vein by bypassing the capillaries
5
Q
Where does arteriovenous anastomosis most frequently occur?
A
arteriovenous anastomosis occurs most frequently in the fingers, ears, and toes
6
Q
What is the function of arteriovenous anastomosis occur?
A
arteriovenous anastomosis is responsible for reducing heat loss in cold weather by allowing blood to bypass the exposed surfaces
7
Q
What is arterial anastomosis?
A
arterial anastomosis is when two arteries merge
8
Q
What is the function of arterial anastomosis?
A
arterial anastomosis is responsible for providing alternative routes of blood supply to tissues
9
Q
What is a venous anastomosis?
A
a venous anastomosis is a connection between two veins
10
Q
What is the function of a venous anatomosis?
A
a venous anastomosis is responsible for providing several alternative routes of drainage from and organ
11
Q
What is the most common type of anastomosis?
A
the most common type of anastomosis is the venous anastomosis
12
Q
What is the tunica externa (tunica adventitia)?
A
the tunica externa is the outermost layer of the vessel wall
13
Q
What makes up the tunica externa (tunica adventitia)?
A
the tunica externa is made up of loosely woven collagen fibers that protect and reinforce the vessel
14
Q
What are some of the important component that the tunica externa contains?
A
the tunica externa contains nerve fibers, lymphatic vessels, and in larger vessels vasa vasorum
15
Q
What is the tunica media?
A
the tunica media is the thick, middle layer of the vessel wall
16
Q
What makes up the tunica media?
A
the tunica media is made up of smooth muscle, collagen, and some elastic tissue
17
Q
What regulate the smooth muscle within the vessel wall?
A
the smooth muscle within the vessel wall is regulated by the sympathetic vasomotor neurons and autonomic nervous system which allows vasoconstriction and vasodilation to occur
18
Q
What is the tunica intima?
A
the tunica intima is the smooth inner layer of the vessel wall
19
Q
What makes up the tunica intima?
A
the tunica intima is made up simple squamous epithelium that when exposed to blood in the lumen, repels blood a platelets
20
Q
What percentage of blood do arteries and arterioles contain
A
arteries and arterioles contain about 15% of total blood at rest
21
Q
What are the elastic (conducting) arteries?
A
the elastic arteries are the largest arteries in size; interstate highways
22
Q
What are some examples of elastic arteries?
A
some examples of elastic arteries are the aorta, pulmonary arteries, and carotid arteries
23
Q
What are some of the characteristics of elastic arteries?
A
elastic arteries are thick-walled, close to the heart, and have low resistance; they also expand and recoil during systole and diastole
24
Q
What are muscular (distributing) arteries?
A
muscular distributing arteries are smaller arteries that distribute blood to specific organs
25
What are some examples of muscular (distributing) arteries?
some examples of muscular arteries are the brachial and femoral arteries
26
What are some characteristics of muscular (distributing) arteries?
muscular distributing arteries have a thick tunica media with more smooth muscle, are also more active in vasoconstriction, and are also less capable of stretching
27
What are arterioles?
arterioles are the smallest arteries
28
What is the function of arterioles?
arterioles are responsible for constricting and dilating the amount of blood that flows to and organ/ tissue
29
What is the pathway of metarterioles?
metarterioles continue through the bed and lead directly to the venules
29
What are metarterioles?
metarterioles are short vessels that connect arterioles to capillaries
30
What are capillary beds?
capillary beds are groups of capillaries (10 - 100) that are supplied by a single metarteriole
30
What are capillaries?
capillaries are the smallest vessels where exchange between blood and tissue occurs
30
Describe the capillary wall.
the capillary wall is extremely thin which allows easy movement between vessels and tissue; the lumen is so small that blood cells are forced to move in a single file
31
What is the "lumen" of a blood vessel wall?
the lumen is the most interior part of the vessel wall
31
What is the precapillary sphincter?
the precapillary sphincter are muscle cells that encircle the capillary entrance and control which capillary beds are perfused
32
Describe continuous capillary type.
the continuous capillary type has endothelial cells that have tight junctions with intercellular clefts; the most common capillary type
32
What fraction of capillary beds are open at any given time at rest?
only 1/4 of capillary beds are open at a given time
32
How many types of capillaries are there?
there are three types of capillaries
32
What percentage of blood do capillary beds contain at rest?
capillary beds contain ~5% of total blood at rest
33
What are the three types of capillaries?
the three types of capillaries are continuous, fenestrated, and sinusoids
34
Describe the fenestrated capillary type.
the fenestrated capillary type has endothelial cells that have many pores (fenestrations) that allow the rapid passage of small molecules
35
Where are fenestrated capillaries most likely to be found?
fenestrated capillaries are most likely to be found in organs that require fast absorption or filtration; kidneys/ small intestine
36
Describe the sinusoid capillary type.
sinusoid capillaries are highly modified, leaky, fenestrated capillaries that allow the proteins and blood cells to move
37
In which organs are sinusoid capillaries most likely to appear?
sinusoid capillaries are most likely to appear in the liver, bone marrow, and spleen
38
What percentage of blood do veins and venules contain at rest?
veins and venules contain 55% of total blood at rest
39
Where is the remaining 30% of blood located when the body is at rest?
the rest of the blood (33%) is located in the heart and lungs
39
What is blood flow?
blood flow is the amount of blood flowing though an organ, tissue, or blood vessel at any given time
39
What are venules?
venules are small veins
39
What is the function of perfusion?
perfusion is responsible for governing the speed of oxygen and nutrient delivery to tissue and waste removal
39
What does the term "perfusion" indicate?
the term "perfusion" indicates the flow per given volume or mass of tissue
39
What is the function of venules?
venules are where blood flows after leaving the capillary bed
39
What is hemodynamics?
hemodynamics is the physical principles of blood flow which are based in pressure and resistance
39
Describe the characteristics of veins.
veins have thin walls (not very muscular and have elastic tissue) and are low pressure vessels; they also have large lumens that can easily expand with high capacities
39
What determines blood pressure?
blood pressure is determined by cardiac output, blood volume, and peripheral resistance
40
What is diastolic blood pressure?
diastolic blood pressure is the blood pressure during ventricular diastole (relaxation)
40
What is the formula for measuring hemodynamics?
flow (f) = change in pressure/ resistance
40
What is systolic blood pressure?
systolic blood pressure is the blood pressure during ventricular systole (contraction)
40
Describe the blood pressure characteristics of a young adult?
a healthy young adults blood pressure is typically 120/80 mmHg; rises with age due to arteries losing elasticity
41
Describe the blood pressure characteristics someone with hypertension?
in the case of hypertension, the individual has a chronic resting blood pressure of more than 140/90 mmHg; this can weaken small arteries and cause aneurysms
41
What is the cause of hypotension (low blood pressure)?
hypotension can be caused by blood loss, anemia, and dehydration
41
Describe the blood pressure characteristics of someone with hypotension?
in the case of hypotension, the individual has a chronically low blood pressure level
42
How can you measure pulse pressure?
pulse pressure can be measured by subtracting the diastolic blood pressure from the systolic blood pressure
43
Why is pulse pressure important?
pulse pressure is important because it is an indicator of stress in small vessels
44
What is the mean arterial pressure (map)?
the mean arterial pressure is another method of measuring stress on the blood vessels
45
What is the equation for measuring mean arterial pressure?
mean arterial pressure = diastolic blood pressure + .33 (pulse pressure)
46
What is peripheral resistance?
peripheral resistance is the resistance that blood encounters in the vessel as it travels away from the heart
47
What three things determine peripheral resistance?
peripheral resistance is determined blood viscosity, vessel length, and vessel radius
48
How does blood viscosity contribute to peripheral resistance?
blood viscosity contributes to peripheral resistance because it determines how thick the blood is
49
How does vessel length contribute to peripheral resistance?
vessel length contributes to peripheral resistance because pressure and flow decrease with distance
50
How does vessel diameter contribute to peripheral resistance?
vessel diameter contributes to peripheral resistance because the smooth muscle of the tunica media can contract and relax
51
Which variable of peripheral resistance is most adjustable?
the most adjustable peripheral resistance is the vessel diameter
52
In terms of peripheral resistance, what happens if the radius of a vessel is doubled?
if the radius of a vessel is doubled the resistance is only 1/16 as much and flow increases
53
Which vessel(s) has the fastest blood flow?
the aorta has the fastest blood flow
54
Which vessel(s) has the slowest blood flow?
the capillaries have the slowest blood flow
55
What are three reasons blood flow decreases in the vessels?
three reasons blood decreases in the vessels are that there is a greater distance traveled (more friction), smaller radii of arterioles and capillaries, and the vessel is farther from the heart
56
Is the regulation of blood flow a part of the peripheral or autonomic nervous system?
the regulation of blood flow is a part of the autonomic nervous system
57
What is local control (autoregulation)?
local control is the ability to tissues to regulate their own blood supply
58
Describe happens if a tissue is inadequately perfused.
if a tissue is inadequately perfused it accumulates waste products which stimulate vasodilation; when waste products are removed the vessels constrict
59
What are two examples of short term regulation of blood pressure and flow?
Two examples of short term regulation and flow are the neural and hormonal controls
60
What is a baroreflex?
is a change in blood pressure that is detected by a baroreceptor
61
What is a baroreceptor?
a baroreceptor is a stretch receptor located in the aorta/ carotid above the heart
62
Describe the first step of the autonomic negative feedback response in reference to the cardiovascular system.
the autonomic negative feedback response are when baroreceptors send constant feedback via different fibers to the cardiovascular center of the medulla
63
What is a chemoreflex?
a chemoreflex is when chemical receptors in the aorta (aortic bodies) and carotids (carotid bodies) respond to blood chemistry (pH, co2, o2)
64
What is the primary role of a chemoreflex?
the primary role of a chemoreflex is to adjust respiration
65
Describe the secondary role of a chemoreflex.
if the chemical receptors detect hypoxia and acidity they will stimulate the chemoreceptors and increase action potentials to the cardioacceleratory and vasomotor center; this in turn increases cardiac output which increases blood pressure and increases perfusion and exchange
66
Which hormones can influence blood pressure and flow?
angiotensin II, aldosterone, antidiuretic, epinephrine, and norepinephrine are all hormones that can influence pressure and blood flow
67
How do hormones influence blood pressure and blood flow?
hormones can influence blood pressure and flow by arterial vasoconstriction/ vasodilation or water retention/ excretion
68
Describe the second step of the autonomic negative feedback response in reference to the cardiovascular system.
an increase in blood pressure causes an increased rate of action potentials to be sent to the cardiovascular center which inhibits the vasomotor and cardioaccelerator centers; the cardioinhibitory center in simulated which causes arteriolar and venous dilatation and a decreased cardiac output or decrease in blood flow
69
Describe the third step of the autonomic negative feedback response in reference to the cardiovascular system.
a decrease in blood flow causes the action potential rate to drop and excite the vasomotor and cardioacceleratory center which inhibits cardioinhibitory center; causes vasoconstriction and increased cardiac output and increased blood pressure
70
Describe the last step of the autonomic negative feedback response in reference to the cardiovascular system.
overtime the baroreceptors adapt to chronic high or low pressure and they quit responding; other mechanisms take over (renal)
71
How can the kidneys (renal) directly control the blood pressure?
the kidneys can eliminate or retain fluid to control blood pressure
72
How can the kidneys (renal) indirectly control the blood pressure?
the kidneys can control the renin-angiotensin mechanism which increases blood viscosity/ blood pressure by retaining fluids
73
Describe the routing of blood flow.
localized vasoconstriction of the arterioles enables routing of blood to different organs/ tissues
74
How can arterioles influence peripheral resistance?
arterioles can control peripheral resistance by changing their diameter
75
True or False: Muscular constriction in the capillary bed can determine where blood is sent.
true; muscular constriction on the proximal side of the capillary bed determines where blood is sent
76
What happens to blood flow in the arteries during exercise?
during exercise, arterioles redirect blood from internal (gi tract) to skeletal muscle, lungs, and myocardium
77
What is capillary exchange?
capillary exchange is the passage of substances between the blood and tissue through the capillary wall
78
What are the four types of capillary exchange?
the four types of capillary exchange are diffusion, transcytosis, filtration, and reabsorption
79
What is diffusion?
diffusion is the most important mechanism for exchange
80
Describe the diffusion of lipid-soluble substances.
lipid soluble substances diffuse easily
81
Describe the diffusion of lipid-insoluble substances.
insoluble substances must pass through channels, fenestrations, or intercellular clefts
82
What are two different types of lipid-soluble substances?
two different types of lipid-soluble substances are oxygen and carbon dioxide
83
What are two different types of lipid-insoluble substances?
two different types of lipid-insoluble substances are glucose and electrolytes
84
Which two particles are often held back during diffusion?
Two particles that are held back during diffusion are protein and blood cells
85
Describe the process of transcytosis?
endothelial cells pick up droplets of fluids that contain substances and transport the vesicles across the membrane in order to release the fluid/ substance on the other side of the membrane
86
Which substances use transcytosis to move across the cell membrane?
substances that use transcytosis to move across the membrane are fatty acids, albumin, and insulin
87
What is the function of blood (hydrostatic) pressure?
blood pressure drives fluid out of the capillary with high pressure on the arterial end and low pressure of the venous end
88
What is the function of colloid osmotic pressure?
colloid osmotic pressure draws fluid into the capillary due to more substances in the vessels that attract fluid
89
Where is the process of colloid osmotic pressure most likely to occur?
the process of colloid osmotic pressure is most likely to occur in the venous end of the capillary
90
Describe the pressure gradient.
the pressure in the venules forces blood back into the heart where the pressure in the vena cave is only 4 mmHg
91
How does gravity contribute to venous return of blood?
gravity drains blood from the head and neck
92
What are the four mechanisms of venous return?
four mechanisms of venous return are the pressure gradient, gravity, skeletal muscle pump, and thoracic pump
93
How does the skeletal muscle pump contribute to venous return of blood?
in the limbs that veins are surrounded and squeezed by muscles which move blood along to areas of less compression
94
What are the function of one way valves in the veins?
one way valves ensure the blood only moves in one direction - towards the heart
95
How does the thoracic pump contribute to venous blood flow?
during the process of inhalation the thoracic cavity expands and abdominal pressure increases which forces blood upwards towards the hert
