Chapter 21 - Cardiovascular System: Blood Vessels and Hemodynamics Flashcards
(159 cards)
1
Q
What is hemodynamics?
A
The forces involved in circulating blood throughout the body
2
Q
What are the 5 main blood vessels?
A
- Arteries
- Aterioles
- Capillaries
- Venules
- Veins
3
Q
How do arteries carry blood?
A
Away from the heart to other organs
4
Q
How do veins carry blood?
A
Away from the tissues and back to the heart
5
Q
What are the three basic layers of a blood vessel?
A
- Tunica interna (intima)
- Tunica media
- Tunica externa (adventia)
6
Q
What is the lumen?
A
The interior opening of the blood vessel
- in direct contact with the blood as it flows
7
Q
What is the tunica interna (intima)?
A
The innermost lining of a blood vessel
- in direct contact with blood as it flows
8
Q
What is the tunica media?
A
The middle layer of a blood vessel
- muscular and connective tissue layer
9
Q
What is the tunica externa (adventia)?
A
The outermost layer of a blood vessel
10
Q
What is vasoconstriction?
A
A decrease in the diameter of the lumen of a blood vessel
- when the smooth muscle in the tunica media contract
11
Q
What is vasodilation?
A
An increase in lumen diameter in a blood vessel
12
Q
What are elastic arteries?
A
The largest arteries in the body (largest diameter)
- includes the aorta and pulmonary trunk
- as well as the aorta’s initial branches
13
Q
What is the function of elastic arteries?
A
Help propel blood onward while the ventricles are relaxing
- also called conducting arteries
14
Q
What are muscular arteries?
A
Medium-sized arteries
- capable of great vasocontriction and vasodialation
- able to contract and maintain a partial contraction (vascular tone)
- also called distributing arteries
15
Q
What is the function of arterioles?
A
Regulate the flow of blood into the capillary networks of the body’s tissues
16
Q
What is the metarteriole?
A
The terminal end of the arteriole
- tapers towards the capillary junction
17
Q
What is the function of the precapillary sphincter?
A
Monitors the blood flow into the capillary
18
Q
What is resistance?
A
The opposition to blood flow
- arterioles play a key role in regulating blood flow into capillaries
19
Q
How does vasodilation and vasoconstriction affect blood pressure?
A
Vasoconstriction = increases blood pressure
Vasodilation =decreases blood pressure
20
Q
What are capillaries?
A
The smallest blood vessel
- connect arterial outflow to the venus return
21
Q
What is microcirculation?
A
The flow of blood from a metarteriole through capillaries and into a postcapillary venule (venule that receives blood from a capillary)
22
Q
What is the primary function of capillaries?
A
The exchange of substances between the blood and interstitial fluid
23
Q
What is a capillary bed?
A
A network of 10-100 capillaries that arises from a single metarteriole
24
Q
What is the thoroughfare channel?
A
Provides a direct route for blood from an arteriole to a venule, thus by-passing capillaries
25
What are the three kinds of capillaries?
1. Continuous capillaries
2. Fenestrated capillaries
3. Sinusoids
26
Describe continuous capillaries.Where are they found?
The plasma membranes of endothelial cells form a continuous tube that is interrupted only by intercellular clefts (gaps between neighbouring endothelial cells)
- found in CNS, lungs, skin, muscle tissue
27
Describe fenestrated capillaries.Where are they found?
Plasma membranes of the endothelial cells have many small pores (fenestrations)
- found in kidneys, villi of small intestine, choroid plexuses of the ventricles of the brain, ciliary processes of the eyes and most endocrine glands
28
Describe sinusoids.Where are they found?
Wider and more winding than other capillaries
| - liver, spleen, anterior pituitary, parathyroid, adrenal glands
29
How does blood circulate in a portal system?
Blood passes from one capillary network into another through a vein (portal vein)
30
What is the function of venules?
Drain the capillary blood and begin the return flow back towards the heart
31
Describe the major structural differences between veins and arteries.
Vein
| - thin walls relative to diameter, blood pressure is lower in veins, lumen is larger in veins
32
What do veins contain that arteries do not?
Valves!
33
What is the function of venus valves?
Valves aid in venus return by preventing the backflow of blood
- low blood pressure in veins allows blood returning to the heart to slow and even back up
34
What is a vascular (venous) sinus?
A vein with a thin endothelial wall that has no smooth muscle
- dense connective tissue replaces the tunica media & tunica externa in providing support
35
What is an anastomosis?
The union of the branches of two or more arteries supplying the same body region
36
What is collateral circulation?
The alternative route of blood flow to a body part through an anastomosis
- may also occur between veins/arterioles/venules
37
How is your blood distributed when your body is at rest?
```
64% in systemic veins and venules
13% in systemic arteries
7% in systemic capillaries
9% in pulmonary blood vessels
7% in the heart
```
38
What function as blood reservoirs of the body?
Systemic veins and venules
| - contain a larger percentage of the blood volume
39
Name the 5 types of blood vessels in order as the leave the heart.
1. Arteries
2. Arterioles
3. Capillaries
4. Venules
5. Veins
40
What is capillary exchange?
The movement of substances between blood and interstitial fluid
41
What are the three basic mechanisms for capillary exchange?
1. Diffusion
2. Transcytosis
3. Bulk flow
42
What is the most important method of capillary exchange?
Diffusion
| - important for SOLUTE exchange
43
What are some examples of substances that enter and leave capillaries by simple diffusion?
- oxygen
- carbon dioxide
- glucose
- amino acids
- hormones
44
What is transcytosis?
Method of capillary exchange
- substances in blood plasma become enclosed within tiny pinocytic vesicles that first enter endothetlial cells by endocytosis, then move across the cell and exit on the other side by exocytosis
45
What is transcytosis important for?
Important for movement of large, lipid in
| -soluble molecules that cannot cross capillary walls in any other way
46
What is bulk flow?
Method of capillary exchange
- passive process in which LARGE numbers of ions, molecules or particles in a fluid move together in the same direction
- move faster than diffusion
47
When does bulk flow occur?
Occurs from an area of higher pressure to an area of lower pressure
48
What is bulk flow important for?
Regulation of the relative volumes of blood and interstitial fluid
49
What is filtration?
Pressure-driven movement of fluid and solutes FROM blood capillaries INTO intersitial fluid
50
What is reabsorption?
Pressure-driven movement FROM interstitial fluid INTO blood capillaries
51
What two pressures promote filtration?
1. Blood hydrostatic pressure
| 2. Interstitial fluid osmotic pressure
52
What two pressures promote reabsorption?
1. Blood colloid osmotic pressure
| 2. Interstitial fluid hydrostatic pressure
53
What is the net filtration pressure (NFP)?
Balance of filtration and reabsorption
| - determines whether the volume of blood and interstitial fluid remains steady or changes
54
What does blood hydrostatic pressure do (BHP)?
"Pushes" fluid out of capillaries into interstitial fluid
55
What does interstitial fluid osmotic pressure do (IFOP)?
"Pulls fluid from capillaries into interstitial fluid
| - approx. 1 mmHg
56
What does blood colloid osmotic pressure do (BCOP)?
"Pulls" fluid from interstitial spaces into capillaries
57
What does interstitial fluid hydrostatic pressure do (IFHP)?
"Pushes" fluid from interstitial spaces into capillaries
| - approx. 0 mmHg
58
What is the equation for determining net filtration pressure (NFP)?
NFP = (BHP+IFOP) - (BCOP+IFHP)
59
What force opposes BHP?
IFHP (interstitial fluid hydrostatic pressure)
60
What force opposes BCOP?
IFOP (interstitial colloid osmotic pressure)
61
When will filtration occur?
If pressure that pushes fluid into capillaries >pressure that pulls fluid into capillaries--> fluid will move from capillaries into interstitial spaces
62
When will reabsorption occur?
If pressure that pushes fluid out of interstitial spaces >pressure that pulls fluid out of capillaries--> fluid will move from interstitial spaces into capillaries
63
What is an edema?
An abnormal increase in interstitial fluid volume
| - caused if filtration greatly exceeds reabsorption
64
What is blood flow?
Volume of blood that flows through any tissue in a given time period (in mL/min)
65
What is blood pressure?
Hydrostatic pressure exerted by blood on the walls of a blood vessel
- highest in aorta
66
What is systolic blood pressure?
Highest pressure attained in arteries during systole
67
What is diastolic blood pressure?
Lowest arterial pressure during diastole
68
What happens to blood pressure the farther away you get from the left ventricle?
Continues to fall, until 0 when it reaches the right ventricle
69
What is the mean arterial pressure (MAP)?
Average blood pressure in arteriesMAP = diastolic BP + 1/3(systolic BP - diastoltic BP)
70
What is vascular resistance?
Opposition to blood flow due to friction between blood and the walls of blood vessels
71
What three things does vascular resistance depend on?
1. Size of blood vessel lumen
2. Blood viscosity
3. Total blood vessel length
72
How does the size of a blood vessel lumen affect vascular resistance?
Smaller the lumen of a blood vessel, the greater its resistance
- if arteries dilate = resistance decreases, pressure falls
- if arteries constrict = resistance increases, pressure rises
73
How does blood viscosity affect vascular resistance?
Higher the blood's viscosity, the higher the resistance
74
How does total blood vessel length affect vascular resistance?
Longer the blood vessel, the greater the resistance
75
What is systemic vascular resistance (SVR)?(total peripheral resistance, TPR)
All the vascular resistances offered by systemic blood vessels(size of lumen, blood viscosity, blood vessel length)
76
What is venous return?
The volume of blood flowing back to the heart through the systemic veins
- occurs due to the pressure generated by contractions of the heart's left ventricle
77
Besides the heart, what are the other two mechanisms that "pump" blood from the lower body back to the heart?
1. Skeletal muscle pump
| 2. Respiratory pump
78
How does the skeletal muscle pump operate?
1. When you stand at rest, both the proximal and distal valves (venous return) are open and blood flows upwards towards the heart
2. Contractions of leg muscles, compresses the vein
- pushes blood through the proximal valve, distal valve is pushed closed
3. Just after muscle relaxation, pressure falls in the previously compressed section of the vein, causes the proximal valve to close
- distal valve now opens, vein fills with blood from the foot
79
What happens during inhalation to the respiratory pump?
During inhalation
- the diaphragm moves downward, causes a decrease in pressure in the thoracic cavity and an increase in pressure in the abdominal cavity
- abdominal veins are compressed
- greater volume of blood moves from compressed abdominal veins to decompressed thoracic veins and then into the right atrium
80
What happens during exhalation to the respiratory pump?
During exhalation
- pressure reverses during exhalation, increase in thoracic cavity pressure and a decrease in pressure in abdominal cavity
- valves in the veins prevent backflow of blood from the thoracic veins to the abdominal veins
81
What is the velocity of blood flow?
The speed of blood flow
- inversely related to the cross-sectional area
- velocity is slowest when cross-sectional area is greatest (capillaries)
82
How does the velocity of blood flow aid in capillary exchange?
Slow rate of flow through capillaries aids the exchange of materials (more time for diffusion)
83
What is circulation time?
Time required for a drop of blood to pass from the RIGHT ATRIUM, through pulmonary circulation, into LEFT ATRIUM, through systemic circulation and back again to the right atrium.
- resting adult, approx. 1 minute.
84
What are the cardiac output factors that increase blood pressure?
- increased stroke volume (increased venous return: increased blood volume, skeletal and respiratory pumps, venoconstriction; increased sympathetic impulses and hormones)
- increased heart rate (decreased sympathetic impulses and increased sympathetic impu
85
What are the systemic vascular resistance factors that increase blood pressure?
- increased blood viscosity (increase # of red blood cells)
- increased blood vessel length (increased body size)
- decreased blood vessel radius (vasoconstriction)
86
What is the function of the cardiovascular center?
Helps regulate heart rate and stroke volume
- also neural, hormonal, and local negative feedback systems that regulate blood pressure and blood flow to specific tissues
87
What are the 4 main inputs that provide information to the cardiovascular center (nerve impulses)?
1. From higher brain centers (cerebral cortex, limbic system, hypothalamus)
2. Proprioceptors (monitor joint movements)
3. Barorecptors (monitor blood pressure)
4. Chemoreceptors (monitor blood acidity)
88
What are the 3 main outputs that provide information from the cardiovascular center?
1. Vagus nerves (decreased heart rate)
2. Cardiac accelerator (increase heart rate and contractility)
3. Vasomotor nerves (blood vessels: vasoconstriction)
89
What happens along the cardiac accelerator nerves?
Sympathetic impulses reach the heart
| - increases heart rate and contractility
90
What is conveyed along the vagus (X) nerves?
Parasympathetic stimulation
| - decreases heart rate
91
What is conveyed along the vasomotor nerves?
Impulses to smooth muscle in blood vessels
| - sympathetic nerves
92
What is vasomotor tone?
Moderate state of tonic contraction or vasoconstriction
| - sets the resting level of systemic vascular resistance
93
What are the 2 negative feedback loops that occur as two types of reflexes?
1. Baroreceptor reflexes
| 2. Chemoreceptor reflexes
94
What are baroreceptors and where are they located?
Pressure-sensitive receptors- located in the aorta, internal carotid arteries and other large arteries (neck and chest)
95
What is the important function of baroreceptors?
Send impulses to the cardiovascular center to help regulate blood pressure
96
What are the 2 important baroreceptor reflexes called?
1. Carotid Sinus Reflex
| 2. Aortic Reflex
97
What does the carotid sinus reflex regulate?
Regulates blood pressure in the brain
98
What does the aortic reflex regulate?
Regulates systemic blood pressure
99
What do baroreceptors do when blood pressure falls?
Receptors are stretched less
Send nerve impulses at a slower rate
Cardiovascular center slows parasympathetic stimulation, increases sympathetic stimulation
Heart beats faster
Systemic vascular resistance increases, cardiac output increases, blood pressure returns to normal.
100
What are the 2 chemoreceptor reflexes?
Carotid bodiesAortic bodies
101
What do carotid and aortic bodies detect?
Changes in blood levels of oxygen, carbon dioixide and hydrogen
102
What is hypoxia?
Low oxygen levels available
103
What is acidosis?
Increase in H+ concentration in the blood
104
What is hypercapnia?
Excess carbon dioxide in the blood
105
Describe the renin-angiotensin-aldosterone (RAA) system.
Blood volume falls or blood flow to the kidneys decreases
- kidneys secrete renin- renin is converted to angiotensin II, which raises blood pressure in two ways (vasoconstrictor and secretion of aldosterone)
- aldosterone increases reabsorption of Na+ and water by the kidneys
- water reabsorption increases total blood volume, which raises blood pressure
106
What effect does epinephrine and norepinephrine have blood pressure?
Increase cardiac output by increasing the rate & force of heart contraction; increase blood pressure
- also cause vasoconstrictionof arterioles & veins in the skin and vasodilation of arterioles in cardiac & skeletal muscles.
Increase blood flow to muscles during exercise
107
What effect does ADH (antidiuretic hormone) have on blood pressure?
Causes vasoconstriction, increases blood pressure
- also promotes movement of water from the lumen of kidney tubules into the bloodstream, increases blood volume, decreases urine output
108
What effect does ANP (atrial natriuretic peptide) have on blood pressure?
Lower blood pressure by causing vasodilation
| - promoting loss of salt and water in the urine, which reduces blood volume
109
What is auto-regulation?
Ability of a tissue to automatically adjust its blood flow to match its metabolic demands
110
What are the two general types of stimuli that cause auto-regulation in blood flow?
1. Physical changes (warming = vasodilation, cooling = vasoconstriction)
2. Vasodilating and vasoconstricting chemicals
111
What is the myogenic response?
- contract more forcefully when it is stretched
| - relaxes when stretching lessons
112
What happens to PULMONARY circulation when exposed to low levels of oxygen?
VASOCONSTRICTION!
113
What is the pulse?
Alternate expansion & recoil of elastic arteries after each systole of the LEFT ventricle
- creates a traveling pressure wave (pulse)
- normally 70-80 beats/min
114
What is tachycardia?
A rapid resting heart or pulse rate
| - over 100 beats/min
115
What is bradycardia?
Slow resting heart or pulse rate
| - under 50 beats/min
116
What does a sphygmomanometer measure?
Blood pressure
117
What does the term blood pressure refer to?
Pressure in arteries generated by the LEFT ventricle during systole and the pressure remaining in the arteries when the ventricle is in diastole
118
What is systolic blood pressure (SBP)?
Sound corresponds to the force of blood pressure on arterial walls just after ventricular contraction
119
What is diastolic blood pressure (DBP)?
Sound becomes too faint to be heard through the stethoscope
| - represents the force exerted by the blood remaining in arteries during ventricular relaxation
120
What are Korotkoff sounds?
Various sounds that are heard while taking blood pressure
121
What is pulse pressure?
The difference between systolic and diastolic pressure
| - normally about 40 mmHg
122
What is shock?
A failure of the cardiovascular system to deliver enough oxygen and nutrients to meet cellular metabolic needs- cells switch from aerobic to anaerobic production of ATP
123
What are the 4 different kinds of shock?
1. Hypovolemic shock
2. Cardiogenic shock
3. Vascular shock
4. Obstructive shock
124
What is hypovolemic shock and what is a common cause?
Decreased blood volume
- acute (sudden) hemorrhage- blood loss may be external or internal
- sweating, diarrhea, vomiting, not enough fluid intake
125
What is cardiogenic shock and what is a common cause?
Poor heart function
| - due to a heart attack (myocardial infarction)
126
What is vascular shock and what is a common cause?
Inappropriate vasodilation- severe allergic reaction
127
What is obstructive shock and what is a common cause?
Due to an obstruction of blood flow
| - pulmonary embolism (blood clot in the lungs)
128
What are 4 homeostatic responses to shock?
1. Activation of the renin-angiotensin-aldosterone system
2. Secretion of antidiuretic hormone
3. Activation of the sympathetic division of ANS
4. Release of local vasodilators
129
What are some signs/symptoms of shock?
- systolic blood pressure lower than 90 mmHg
- rapid resting heart rate (sympathetic stimulation)
- pulse is weak and rapid (reduced cardiac output)
- skin is cool, pale and clammy (constriction to skin vessels)
- mental state is altered (reduce O2 to brain)
130
What are the subdivisions of the systemic circulation system?
1. Coronary (cardiac) circulation
2. Cerebral circulation
3. Hepatic portal circulation
131
What does the coronary (cardiac) circulation supply?
Supplies the myocardium of the heart
132
What does the cerebral circulation supply?
Supplies the brain
133
What does the hepatic portal circulation supply?
Extends from gastrointestinal tract to the liver
134
What does systemic circulation do?
Carries oxygen and nutrients to body tissues and removes wastes
135
Where does blood flow to from the left ventricle?
Pumped into Ascending Aorta
136
From the Ascending Aorta, where does blood flow?
1. Right and left coronary arteries (serve the heart)
| 2. Arch of the aorta
137
What branches off of the Arch of the Aorta?
1. Brachiocephalic trunk
2. Left common carotid artery
3. Left subclavian artery
4. Descending artery
138
What happens to blood as it flows through the brachiocephalic trunk?
Right subclavian artery and right common carotid artery (internal and external right carotid arteries)
139
What happens to blood as it flows through the left common carotid artery?
Flows into internal and external left carotid arteries
140
What happens to blood as it flows through the left subclavian artery?
Axillary artery --> Brachial artery --> Radial and ulnar arteries
141
What region does the external iliac arteries supply?
Lower abdominal wall, lower limb, uterus in females
142
Where does the right atrium receive blood from?
1. Coronary sinus
2. Superior Vena cava
3. Inferior vena cava
143
What does the coronary sinus receive blood from?
Cardiac veins
144
What does the superior vena cava receive blood from?
Right and left brachiocephalic veins
145
What does the right and left brachiocephalic veins receive blood from?
Internal jugular vein
External jugular vein
Subclavian vein
146
What does the inferior vena cava receive blood from?
Hepatic veins, right and left renal veins, gonadal veins and common iliac veins
147
What does the common iliac veins receive blood from?
Internal and external iliac veins
148
What does the external iliac veins receive blood from?
Femoral veins
149
What does the femoral veins receive blood from?
Great Saphenous vein
| Anterior and Posterior tibial vein
150
Describe hepatic portal circulation.
Nutrient-rich blood from the digestive system is carried to the liver by the hepatic portal vein
151
Describe pulmonary circulation.
Right ventricle (de-oxygenated blood) --> pulmonary trunk --> right and left pulmonary arteries --> alveoli of lungs --> return by 4 pulmonary veins --> left atrium
152
What is hypertension?
Persistently high blood pressure
153
What is an aneurysm?
A thin, weakened section of the wall of an artery or a vein that bulges outward, forming a balloon-like sac
154
What is deep vein thrombosis (DVT)?
Presence of a thrombus (blood clot) in a deep vein of the lower limbs
155
What is hypotension?
Low blood pressure
| - during excessive blood loss
156
What is occlusion?
Closure or obstruction of the lumen of a structure such as a blood vessel
157
What is phlebitis?
Inflammation of a vein, often in a leg
158
What is thrombophlebitis?
Inflammation of a vein involving clot formation
159
What is white coat (office) hypertension?
Stress-induced syndrome found in patients who have elevated blood pressure when being examined by health-care personnel but otherwise have normal blood pressure
