Chapter 18 Flashcards
Cardiovascular System - The Blood Vessels (77 cards)
1
Q
what is your vasculature
A
your billions of blood vessels that transport blood to the tissues
2
Q
what are the functions of your vasculature
A
- transport blood to tissues
- transport waste back to heart
- regulate blood flow to tissues
- control blood pressure
- secrete chemicals
3
Q
collectively, your vasculature measures over how long
A
over 96 000 km long
4
Q
what are arteries
A
- Carry blood away from the heart
- Transport blood under high pressure
- Are thick-walled
5
Q
what are capillaries
A
- Exchange solutes and water with cells of the body
- Are microscopic
6
Q
what are veins
A
- Return blood to the heart
- Are thin-walled
7
Q
what is the distribution system of the vasculature
A
arteries
8
Q
what is the exchange system of the vasculature
A
capillaries
9
Q
arteries are the __________ system of the vasculature
A
distribution
10
Q
what is the collection system of the vasculature
A
veins
11
Q
capillaries are the __________ system of the vasculature
A
exchange
12
Q
what are arterioles
A
Smallest arteries, all contain smooth muscle
13
Q
arteries are comprised of what kind of tissue
A
elastic
14
Q
what is the function of veins
A
Drain blood from capillary beds and return it to the heart; Small veins merge with others to become progressively larger
In the pulmonary circuit, veins transport oxygenated blood; In the systemic circuit, veins transport deoxygenated blood
15
Q
veins are the __________ system of the vasculature
A
collection
16
Q
what is the function of arteries
A
Travel away from the heart, branching into vessels of progressively smaller diameter
Arteries in the pulmonary circuit carry deoxygenated blood, while those in the systemic circuit carry oxygenated blood
17
Q
what is the function of capillaries
A
Smallest diameter; Form branching networks of Capillary Beds
Gases, nutrients, wastes, and other substances are exchanged between the cells and the blood through the capillary walls
18
Q
are there more veins or arteries
A
veins
19
Q
what are the smallest veins
A
venules
20
Q
what are venules
A
Smallest veins; Drain blood from capillary beds
21
Q
what is vasodilation
A
the dilatation of blood vessels, which decreases blood pressure.
precapillary sphincters are relaxed
22
Q
what is vasoconstriction
A
the constriction of blood vessels, which increases blood pressure.
precapillary sphincters are constricted
23
Q
what are venous valves
A
Endothelial flaps. Prevent backflow in the veins; Numerous in the legs
24
Q
pump composed entirely of …
A
living cells and cellular materials
25
output of heart is
5 to 25 litres of blood per minute
26
what is normal heart rate at rest
75 bpm
27
how fast can heart rate accelerate to
over 200 bpm
28
the heart can beat on its own, yet heart rate can be modified by ...
the nervous system
29
blood pressure in the pulmonary circuit is much ___________ than in the systemic circuit
lower
30
how is blood pressure measured (units)
mm Hg
31
what is the blood pressure in the pulmonary circuit
15 mm Hg in arteries
5 mm Hg in veins
32
what is the blood pressure in the systemic circuit
120 mmHg - arteries (systolic)
80 mmHg - arteries (diastolic)
80-35 mmHg - arterioles
35-15 mmHg - capillaries
15-5 mmHg - venules
5-0 mmHg - veins
33
what is cardiac output
how much blood is being ejected from the ventricles
34
what is systemic arterial pressure
aka blood pressure
35
what is systolic pressure
pressure during ventricular systole
avg 110-120 mmHg
36
what is diastolic pressure
pressure during ventricular diastole
avg 70-80 mmHg
37
what is mean arterial pressure
Average pressure in the systemic arteries during an entire cardiac cycle; Generally measures around 95 m m H g (ensuring effective organ perfusion and tissue oxygenation.)
38
what is pulse pressure
Difference between pressures; About 40 m m H g (this reflects the force the heart generates with each contraction).
39
*What is the equation to calculate the MAP
MAP = diastolic pressure + 1/3(systolic pressure - diastolic pressure)
40
how is systemic arterial blood pressure measured
Typically measured in the arm using a Sphygmomanometer and a Stethoscope
41
what is a sphygmomanometer
an instrument for measuring blood pressure, typically consisting of an inflatable rubber cuff which is applied to the arm and connected to a column of mercury next to a graduated scale, enabling the determination of systolic and diastolic blood pressure by increasing and gradually releasing the pressure in the cuff.
42
what is a stethoscope
a medical instrument for listening to the action of someone's heart or breathing, typically having a small disk-shaped resonator that is placed against the chest, and two tubes connected to earpieces.
43
when are the sounds first heard when listening for blood pressure
systolic pressure
44
how do you know systolic pressure while measuring blood pressure
when the sounds are first heard
45
when do the sounds almost stop when listening for blood pressure
diastolic pressure
46
how do you know diastolic pressure while measuring blood pressure
when the sounds almost stop
47
what is systemic capillary pressure
- Pressure continues to decline throughout the remainder of the systemic circuit
- At the arterial end of a capillary bed, the pressure is about 35 m m H g
- At the venular end of the capillary bed, the pressure has decreased to about 15 m m H g
- This decrease is largely due to the reduction in blood volume that takes place in capillaries
48
what is systemic venous pressure
- Pressure declines further in the venules and veins, dropping to only about 4 m m H g in the inferior vena cava and as low as 0 m m H g in the right atrium
- Due largely to the high compliance of veins and declining resistance as these vessels merge and become larger
49
what are the mechanisms of venous return
- venous valves
- smooth muscles in the walls of veins
- skeletal muscle pump
- respiratory pump
50
how are venous valves a mechanism in venous return
Prevent backflow in the veins
51
how is smooth muscle in the walls of veins a mechanism of venous return
May contract under sympathetic nervous system stimulation to increase the rate of venous return
52
how is the skeletal muscle pump a mechanism of venous return
Skeletal muscles surrounding the deeper veins of the upper and lower limbs squeeze the blood in the veins and propel it toward the heart as they contract and relax
53
how is the respiratory pump a mechanism of venous return
Similar mechanism for veins of the thoracic and abdominopelvic cavities; Driven by the rhythmic changes in pressure in the cavities that occur with ventilation; During inspiration, high pressure in the abdominopelvic cavity pushes blood in the abdominal veins upward
54
what is hypertension
An abnormally high blood pressure; May be acute (short-term) or chronic (long-term)
55
what is hypotension
Abnormally low blood pressure; May be chronic, but most cases are acute; Defined as a systolic pressure lower than 90 m m H g and/or a diastolic pressure lower than 60 m m H g, but is generally diagnosed if an individual shows symptoms
56
what is circulatory shock
severe hypotension
results in loss of consciousness and organ failure; Insufficient blood pressure to deliver oxygen and nutrients to cells, which can rapidly be fatal
57
What are the stages of hypertension and their blood pressures
- normal (120/80 or less)
- prehypertension (120 - 139 / 80 - 89)
- stage 1 hypertension (140 - 159 / 90 - 99)
stage 2 hypertension (160/100 or more)
58
what are treatments for hypertension
Two key areas in treatment are lifestyle modifications, including smoking cessation, weight loss if needed, limited alcohol intake, increased physical activity, dietary modifications including decreased salt, cholesterol, and saturated fat intake
59
what is tissue perfusion
Blood flow to a tissue through a capillary bed; Occurs in most tissues except cartilage, the sclera and cornea of the eye, and epithelial tissue
60
what are pericytes
Contractile fibers around some capillaries. Pericytes can contract and relax, which allows them to regulate the diameter of capillaries and control blood flow at the microvascular level. This is particularly important for matching blood supply with the metabolic needs of tissues.
61
what are the mechanisms for capillary exchange to take place
- diffusion through the membranes of endothelial cells
- diffusion and osmosis through gaps and fenstrations
- transcytosis through endothelial cells
62
what are fenestrations
tiny pores in capillaries
63
explain transcytosis through endothelial cells as a mechanism of capillary exchange
Larger substances are taken into the cell by endocytosis and then leave the other side of the cell by exocytosis
64
what is a perfusion pattern
the pattern of the passage of fluid through the circulatory system or lymphatic system to an organ or a tissue
65
what is the perfusion pattern of the heart
Perfusion pattern is opposite the rest of the systemic circuit; Heart perfusion decreases during systole because it actually squeezes its own arteries during ventricular systole; Perfusion increases during diastole
66
explain diffusion through the membranes of endothelial cells as a mechanism of capillary exchange
Lipid-soluble substances including oxygen, carbon dioxide, and some lipids move easily through the cells
67
explain diffusion and osmosis through gaps and fenestrations as a mechanism of capillary exchange
Many capillaries have small gaps between endothelial cells and some have Fenestrations, or pores, within their cells; Water and small solutes, such as amino acids, can move through these pores
68
what are the types of capillaries from tightest to loosest
- continuous capillaries
- fenestrated capillaries
- sinusoidal capillaries
69
how much of total cardiac output does the heart give to itself and what is its relative mass
recieves 5% of total cardiac output, despite being less than 0.5% of body mass
70
how much of total cardiac output does the heart give to the brain and what is its relative mass
receives 15% of total cardiac output despite being 2% of total body mass
71
what is blood flow in the brain like
Blood flow within the brain to different areas varies; Areas with higher activity require more oxygen; Certain neurotransmitters are direct vasodilators, whereas others act on astrocytes that are in contact with arterioles and they induce vasodilation to increase perfusion to active areas
72
How much can blood flow to skeletal muscles increase during exercise
as much as 50-fold
73
What is hyperemia
the extreme increase in blood flow to skeletal muscle during exercise
74
How do skeletal muscles get blood
- Feed Arteries enter a skeletal muscle, branch into multiple arterioles and end in Terminal Arterioles that supply a capillary bed
- During resting conditions, resistance in feed arteries is high and many terminal arterioles are constricted
- During exercise, conditions around the skeletal muscle fiber dilate the terminal arterioles, which begins to increase tissue perfusion; As exercise continues, other arterioles also dilate; Continued exercise dilates the feed artery
75
what are continuous capillaries
Majority in the body; Located in muscles, skin, and most nervous and connective tissues; Least “leaky” with tight junctions; Most substances diffuse through the endothelial cells or move by transcytosis; Modified continuous capillaries in the brain form the blood brain barrier and have specialized tight junctions
76
what are fenestrated capillaries
Endothelial cells contain fenestrations; Located in endocrine glands, small intestine, and kidneys; Much leakier than continuous capillaries; Pores allow for faster diffusion
77
what are sinusoidal capillaries
Endothelial cells are a discontinuous sheet with an irregular basal lamina and very large pores; Three to four times larger in diameter than other capillaries; Located in liver, spleen, lymphoid organs, and bone marrow; Transfer large substances such as blood cells and larger proteins
