Ch 21 The Cardiovascular System: Blood Vessels and Hemodynamics Flashcards
(151 cards)
1
Q
What do arteries do?
A
Arteries carry blood away from the heart.
2
Q
What are arterioles?
A
Small arteries that regulate blood flow into capillaries and control resistance.
3
Q
What are capillaries?
A
The smallest blood vessels where exchange of nutrients and wastes occurs.
4
Q
What are venules?
A
Small veins that collect blood from capillaries and begin the return to the heart.
5
Q
What are veins?
A
Vessels that return blood to the heart, often containing valves to prevent backflow.
6
Q
What is the tunica interna (intima)?
A
The inner layer of a blood vessel in contact with blood, made of endothelium and basement membrane.
7
Q
What is the endothelium?
A
A thin, smooth lining of flattened cells that reduces blood flow friction and controls vessel function.
8
Q
What is the basement membrane?
A
A structural layer providing support, tensile strength, and guiding repair.
9
Q
What is the internal elastic lamina?
A
A layer of elastic fibers that allows material diffusion between the tunica interna and tunica media.
10
Q
What is the tunica media?
A
The middle layer of smooth muscle and elastic fibers that control vessel diameter.
11
Q
What is vasoconstriction?
A
Narrowing of blood vessels due to smooth muscle contraction.
12
Q
What is vasodilation?
A
Widening of blood vessels due to smooth muscle relaxation.
13
Q
What is the external elastic lamina?
A
A layer of elastic fibers separating the tunica media from the tunica externa.
14
Q
What is the tunica externa?
A
The outer connective tissue layer that anchors vessels to surrounding structures.
15
Q
What is the vasa vasorum?
A
Small blood vessels that supply the walls of large blood vessels.
16
Q
What does high compliance in arteries mean?
A
Arteries stretch easily with small pressure increases.
17
Q
What are elastic arteries?
A
The largest arteries, acting as pressure reservoirs.
18
Q
What are elastic lamellae?
A
Layers of elastic fibers in elastic arteries.
19
Q
What does ‘pressure reservoir’ mean?
A
Elastic arteries store mechanical energy and propel blood forward during heart relaxation.
20
Q
What are conducting arteries?
A
Elastic arteries that move blood from the heart to muscular arteries.
21
Q
What are muscular arteries?
A
Medium-sized arteries with a thick muscular wall, controlling blood flow.
22
Q
What are distributing arteries?
A
Muscular arteries that deliver blood to specific organs.
23
Q
What is vascular tone?
A
Partial contraction of smooth muscle that stiffens vessel walls and maintains pressure.
24
Q
What is an anastomosis?
A
A connection between arteries providing alternate blood flow routes.
25
What is collateral circulation?
Alternate blood flow through an anastomosis.
26
What are end arteries?
Arteries that lack anastomoses; blockage causes tissue death.
27
What is a metarteriole?
The end of an arteriole leading to capillary beds.
28
What is a precapillary sphincter?
A band of smooth muscle controlling blood flow into capillaries.
29
Why are arterioles called resistance vessels?
They regulate blood flow and resistance by changing diameter.
30
What is microcirculation?
Blood flow from arterioles to venules through capillaries.
31
Why are capillaries called exchange vessels?
They are the primary sites for nutrient and waste exchange.
32
What are capillary beds?
Networks of 10–100 capillaries branching from one metarteriole.
33
What is vasomotion?
Intermittent blood flow through capillaries due to sphincter contraction cycles.
34
What is the capillary route?
The pathway from arteriole → capillaries → venule.
35
What is a thoroughfare channel?
A direct connection from arteriole to venule, bypassing capillaries.
36
What are continuous capillaries?
Capillaries with uninterrupted endothelial cells and small intercellular clefts.
37
What are intercellular clefts?
Small gaps between endothelial cells in continuous capillaries.
38
What are fenestrated capillaries?
Capillaries with pores for rapid exchange.
39
What are sinusoids?
Large, winding capillaries with wide gaps allowing cells and proteins to pass.
40
What is a portal system?
Blood flow through two capillary beds connected by a portal vein.
41
What are postcapillary venules?
Small venules that allow exchange and WBC migration.
42
What are muscular venules?
Venules with smooth muscle layers that store blood but do not support exchange.
43
What structural feature helps prevent backflow in veins?
Valves.
44
What are vascular (venous) sinuses?
Thin-walled veins without smooth muscle, like the dural and coronary sinuses.
45
What are anastomotic veins?
Veins that connect superficial and deep venous pathways.
46
What are superficial veins?
Veins located in the subcutaneous layer, not paired with arteries.
47
What are deep veins?
Veins that travel alongside arteries and are primary return pathways.
48
Why are veins called blood reservoirs?
They store a large volume of blood that can be quickly mobilized.
49
What is venoconstriction?
Contraction of venous smooth muscle to move blood into active circulation.
50
What is the primary function of capillaries in the cardiovascular system?
Capillaries allow the exchange of substances between blood and interstitial fluid through diffusion, transcytosis, and bulk flow.
51
What is transcytosis in capillary exchange?
Transcytosis is the process where substances cross capillary walls by being enclosed in pinocytic vesicles that move through endothelial cells via endocytosis and exocytosis.
52
What is bulk flow in capillary exchange?
Bulk flow is the passive, pressure-driven movement of large numbers of ions, molecules, or particles together in one direction, regulating blood and interstitial fluid volumes.
53
What is filtration in capillary exchange?
Filtration is the pressure-driven movement of fluid and solutes from blood capillaries into interstitial fluid.
54
What is reabsorption in capillary exchange?
Reabsorption is the pressure-driven movement of fluid and solutes from interstitial fluid back into blood capillaries.
55
What is blood hydrostatic pressure?
Blood hydrostatic pressure is the pressure exerted by blood against capillary walls, primarily from the heart’s pumping, which drives filtration.
56
What is interstitial fluid osmotic pressure?
Interstitial fluid osmotic pressure is the force exerted by solutes in interstitial fluid that draws water out of capillaries, contributing to filtration.
57
What is blood colloid osmotic pressure?
Blood colloid osmotic pressure is the force generated by plasma proteins in the blood that pulls fluid back into the capillaries, driving reabsorption.
58
What is net filtration pressure?
Net filtration pressure is the balance between filtration and reabsorption pressures that determines the direction of fluid movement across capillary walls.
59
What does inward pressure in capillary exchange refer to?
Inward pressure refers to the net movement of fluid back into capillaries, mainly at the venous end, driven by blood colloid osmotic pressure.
60
What is hemodynamics?
Hemodynamics refers to the forces involved in circulating blood throughout the body.
61
What is blood flow?
Blood flow is the volume of blood moving through a tissue per minute; total blood flow equals cardiac output (CO = HR × SV).
62
What is systolic blood pressure?
Systolic blood pressure is the peak pressure in arteries during ventricular contraction.
63
What is diastolic blood pressure?
Diastolic blood pressure is the lowest arterial pressure during ventricular relaxation.
64
What is mean arterial pressure and how is it calculated?
MAP is the average arterial pressure and is calculated as MAP = DBP + 1/3 (SBP − DBP).
65
What is vascular resistance?
Vascular resistance is the opposition to blood flow due to friction between blood and vessel walls.
66
How does the size of the blood vessel lumen affect resistance?
The smaller the lumen, the greater the resistance to blood flow; resistance increases significantly as the lumen narrows.
67
What is blood viscosity and how does it affect blood pressure?
Blood viscosity is the thickness of blood, influenced by the ratio of RBCs to plasma and plasma proteins. Higher viscosity increases resistance and blood pressure.
68
How does total blood vessel length affect vascular resistance?
The longer the blood vessel, the greater the resistance. Obesity increases total vessel length, raising blood pressure.
69
What is systemic vascular resistance?
It is the total resistance from all systemic blood vessels, mainly regulated by arterioles through vasoconstriction and vasodilation.
70
What is venous return?
Venous return is the volume of blood flowing back to the heart, driven by the pressure difference from venules to the right ventricle.
71
What is the skeletal muscle pump?
It helps venous return by using muscle contractions to compress veins, pushing blood toward the heart through one-way valves.
72
What is the respiratory pump?
It assists venous return by creating pressure changes during breathing. Inhalation draws blood toward the heart, while valves prevent backflow during exhalation.
73
What is circulation time?
Circulation time is the time it takes for blood to travel through the entire cardiovascular system, about one minute in a resting person.
74
What is the cardiovascular center and where is it located?
It is located in the medulla oblongata and regulates heart rate, stroke volume, blood vessel diameter, blood pressure, and blood flow through neural, hormonal, and local feedback systems.
75
What do proprioceptors detect?
They detect joint and muscle movements and increase heart rate at the start of physical activity.
76
What do chemoreceptors monitor?
They monitor blood levels of oxygen, carbon dioxide, and hydrogen ions.
77
What is the function of cardiac accelerator nerves?
They increase heart rate and contractility through sympathetic stimulation.
78
What is the function of the vagus X nerves?
They decrease heart rate through parasympathetic stimulation.
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What is the function of vasomotor nerves?
They control blood vessel diameter by regulating vasoconstriction and vasodilation.
80
What is vasomotor tone?
It is the continuous low-level sympathetic stimulation of blood vessel walls, maintaining resting blood pressure.
81
What do baroreceptors detect?
They detect changes in blood pressure.
82
What is the carotid sinus reflex?
A baroreceptor reflex that regulates blood pressure in the brain via signals through the glossopharyngeal (IX) nerves.
83
Where are carotid sinuses located?
They are located in the internal carotid arteries and help regulate brain blood pressure.
84
What is the aortic reflex?
A baroreceptor reflex that regulates systemic blood pressure via the vagus (X) nerves.
85
Where are carotid bodies located?
Near the carotid sinuses, they contain chemoreceptors that detect oxygen, carbon dioxide, and pH levels.
86
Where are aortic bodies located?
Near the aortic arch, they contain chemoreceptors that monitor blood chemistry.
87
What is the RAAS?
A hormonal system that raises blood pressure by vasoconstriction and increasing blood volume through sodium and water reabsorption.
88
What does angiotensin II do?
It causes vasoconstriction and stimulates aldosterone secretion, raising blood pressure.
89
What is the role of aldosterone in blood pressure regulation?
It increases sodium and water reabsorption in the kidneys, raising blood volume and blood pressure.
90
What effect does epinephrine have on blood pressure?
It increases heart rate and contractility, constricts skin and abdominal vessels, and dilates heart and skeletal muscle vessels.
91
What effect does norepinephrine have on blood pressure?
It works with epinephrine to increase cardiac output and vascular resistance.
92
How does ADH affect blood pressure?
It causes vasoconstriction and increases water reabsorption in the kidneys, raising blood volume and reducing urine output.
93
What is the role of ANP in blood pressure regulation?
It lowers blood pressure by causing vasodilation and promoting salt and water excretion in urine.
94
What is autoregulation of blood flow?
The ability of tissues to adjust their blood flow to meet their own metabolic needs.
95
How do physical changes affect autoregulation?
Warming causes vasodilation, cooling causes vasoconstriction, and the myogenic response adjusts vessel diameter based on stretch.
96
What is the myogenic response?
A reflex where arteriolar smooth muscle contracts when stretched and relaxes when stretch decreases.
97
What chemical signals influence autoregulation?
Vasodilators and vasoconstrictors.
98
What are vasodilators?
Substances that relax blood vessels, increasing blood flow (e.g., nitric oxide, histamine, adenosine).
99
What are vasoconstrictors?
Substances that narrow blood vessels, reducing blood flow (e.g., thromboxane A2, serotonin, endothelins).
100
What is a pulse?
It is a traveling pressure wave caused by the expansion and recoil of elastic arteries after each left ventricular systole.
101
What is tachycardia?
It is a resting heart or pulse rate over 100 beats per minute.
102
What is bradycardia?
It is a resting heart or pulse rate under 50 beats per minute, commonly seen in endurance-trained athletes.
103
What is blood pressure?
It is the pressure in arteries during left ventricular systole and the pressure remaining during diastole.
104
What is a sphygmomanometer?
It is a device used to measure blood pressure, consisting of a cuff, a bulb for inflation, and a pressure gauge.
105
What are Korotkoff sounds?
They are the sounds heard when using a stethoscope to determine blood pressure as the cuff deflates.
106
What is systolic blood pressure?
It is the pressure in arteries during ventricular contraction, identified by the first Korotkoff sound heard as the cuff deflates.
107
What is diastolic blood pressure?
It is the pressure in arteries during ventricular relaxation, identified when Korotkoff sounds disappear.
108
What is pulse pressure?
It is the difference between systolic and diastolic pressures, normally about 40 mmHg, and provides information about cardiovascular health.
109
What is shock?
It is the failure of the cardiovascular system to supply enough oxygen and nutrients to meet the body's cellular needs.
110
What is hypovolemic shock?
Shock caused by acute blood or fluid loss, leading to reduced blood volume, lower venous return, decreased cardiac output, and low BP.
111
What is cardiogenic shock?
Shock caused by heart problems like myocardial infarction, poor perfusion, valve issues, impaired contractility, or arrhythmias.
112
What is vascular shock?
Shock caused by excessive vasodilation that reduces systemic vascular resistance and lowers BP despite normal blood volume.
113
What is anaphylactic shock?
A type of vascular shock from severe allergic reactions causing histamine release, vasodilation, and dangerously low BP.
114
What is neurogenic shock?
A type of vascular shock caused by head trauma that disrupts cardiovascular regulation.
115
What is septic shock?
A type of vascular shock caused by bacterial toxins that induce widespread vasodilation; common in critical care.
116
What is obstructive shock?
Shock caused by blockages in circulation, commonly from a pulmonary embolism.
117
How does the renin–angiotensin–aldosterone system help during shock?
It increases BP through vasoconstriction (angiotensin II) and raises blood volume by promoting sodium and water retention (aldosterone).
118
How does ADH help during shock?
ADH is released in response to low BP, promotes kidney water retention, and causes vasoconstriction to raise BP.
119
How does the sympathetic nervous system respond to shock?
It increases HR, contractility, and vasoconstriction in the skin, kidneys, and abdominal organs to raise BP and venous return.
120
What is the role of local vasodilators during shock?
Hypoxic cells release vasodilators like potassium, hydrogen ions, lactic acid, adenosine, and nitric oxide to improve local oxygen delivery.
121
What are circulatory routes?
They are organized pathways through arteries, arterioles, capillaries, venules, and veins that direct blood flow separately to each organ.
## Footnote
None
122
What is systemic circulation?
It carries oxygenated blood from the left ventricle to the body and returns deoxygenated blood to the right atrium.
## Footnote
None
123
What is pulmonary circulation?
It carries deoxygenated blood from the right ventricle to the lungs for gas exchange and returns oxygenated blood to the left atrium.
## Footnote
None
124
What is coronary circulation?
A subdivision of systemic circulation that supplies oxygenated blood to the heart muscle itself.
## Footnote
None
125
What is cerebral circulation?
A subdivision of systemic circulation that supplies oxygenated blood to the brain.
## Footnote
None
126
What is hepatic portal circulation?
A subdivision of systemic circulation that carries blood from the gastrointestinal tract to the liver for processing.
## Footnote
None
127
What is fetal circulation?
A unique circulatory system in the fetus that facilitates the exchange of materials with the mother.
## Footnote
None
128
What is the function of the superior vena cava?
It returns deoxygenated blood from the upper body to the right atrium of the heart.
## Footnote
None
129
What is the function of the inferior vena cava?
It returns deoxygenated blood from the lower body to the right atrium of the heart.
## Footnote
None
130
What is the coronary sinus?
It collects deoxygenated blood from the heart muscle (coronary circulation) and returns it to the right atrium.
## Footnote
None
131
What is the aorta?
The aorta is the largest artery in the body and carries oxygenated blood from the heart to the systemic circulation.
132
What is the ascending aorta?
It originates from the left ventricle, lies behind the pulmonary trunk, contains the aortic valve, and gives rise to the coronary arteries that supply the heart muscle.
133
What is the arch of the aorta?
It curves to the left, continuing downward to the thoracic region and ending around the 4th or 5th thoracic vertebra.
134
What is the thoracic aorta?
It extends along the thoracic vertebrae and continues until it passes through the diaphragm.
135
What is the abdominal aorta?
It is the continuation of the aorta below the diaphragm and runs to the fourth lumbar vertebra, where it divides into the common iliac arteries.
136
What are the right and left common iliac arteries?
They are the terminal branches of the abdominal aorta that supply blood to the pelvis and lower limbs.
137
Where does the ascending aorta begin?
It begins at the aortic valve
## Footnote
The ascending aorta extends upward, slightly forward, and to the right.
138
Where does the ascending aorta end?
It ends at the sternal angle
## Footnote
This is where it transitions into the arch of the aorta.
139
What structures surround the ascending aorta?
It lies behind the pulmonary trunk and right auricle
## Footnote
The right pulmonary artery is positioned behind the ascending aorta.
140
What are the aortic sinuses?
They are three dilations at the origin of the ascending aorta
## Footnote
Located just above the aortic valve.
141
Where do the coronary arteries originate?
From the right and left aortic sinuses
## Footnote
They form a crown-like ring around the heart.
142
What is the function of the coronary arteries?
They supply blood to the atrial and ventricular myocardium.
143
What is the arch of the aorta and where does it extend?
It is the continuation of the ascending aorta, curving upward, backward, and to the left before turning downward to become the thoracic aorta at the level of the 4th-5th thoracic vertebrae.
144
What is the brachiocephalic trunk?
It is the first and largest branch of the aortic arch, which extends upward and to the right, dividing into the right subclavian artery and right common carotid artery at the right sternoclavicular joint.
145
Where does the right subclavian artery come from and what does it supply?
It branches from the brachiocephalic trunk and supplies blood to the right upper limb and associated structures.
146
What is the left common carotid artery?
It is the second branch of the aortic arch and it supplies the same areas as the right common carotid artery, including parts of the head and neck.
147
What is the left subclavian artery and what does it supply?
It is the third branch of the aortic arch, supplying blood to the left vertebral artery and the arteries of the left upper limb.
148
What is the thoracic aorta?
The thoracic aorta is the continuation of the arch of the aorta that extends downward through the thorax.
## Footnote
The thoracic aorta is a major blood vessel in the body supplying oxygenated blood to the thorax and lower parts of the body.
149
Where does the thoracic aorta begin?
It begins at the intervertebral (IV) disc between the 4th and 5th thoracic vertebrae.
## Footnote
The starting point is significant for understanding the aorta's anatomical relationships.
150
Where does the thoracic aorta lie in relation to the vertebral column?
It lies to the left of the vertebral column but moves closer to the midline as it descends.
## Footnote
This positioning is important for surgical approaches and understanding potential sources of thoracic pain.
151
How does the thoracic aorta pass through the diaphragm?
It passes through the aortic hiatus of the diaphragm, located in front of the vertebral column at the IV disc between the 12th thoracic and 1st lumbar vertebrae.
## Footnote
The aortic hiatus is a critical anatomical landmark for the passage of the aorta into the abdominal cavity.
