Set 5 (Part II) Flashcards
1
Q
Differentiate arteries and veins.
A
- Arteries: carry blood away from the heart
- Veins: return blood to the heart
2
Q
What ensures that blood flows in a single direction?
A
A system of valves in the heart and veins
3
Q
What is the septum?
A
Central wall that divides the heart into left and right halves
4
Q
Differentiate the overall function of the atrium and the ventricle.
A
- Atrium: receives blood returning to the heart into the blood vessels
- Ventricle: pumps blood out into the blood vessels
5
Q
Differentiate the overall function of the left and right sides of the heart.
A
- Right: receives blood from the tissues and sends it to the lungs for oxygenation
- Left: receives newly oxygenated blood from the lungs and pumps it to tissues throughout the body
6
Q
Describe pulmonary circulation.
A
1) Right atrium (tricuspid valve)
2) Right ventricle (pulmonary semi-lunar valve)
3) Pulmonary arteries
4) Lungs
5) Pulmonary veins
6) Left atrium
7
Q
Describe systemic circulation.
A
1) Left atrium (mitral valve)
2) Left ventricle (aortic semilunar valve)
3) Aorta
4) Capillaries deliver oxygen
5) Superior and inferior vena cava veins
6) Right atrium
8
Q
What is the function of coronary arteries?
A
Nourish the heart muscle itself
9
Q
What is the function of the hepatic portal vein?
A
Blood leaving the digestive tract goes directly to the liver
10
Q
A cardiovascular system has what three major components?
A
- Tubes (vessels)
- Fluid (blood)
- Pump (heart)
11
Q
Differentiate pulmonary and systemic circulations.
A
- Pulmonary circulation takes blood to and from the lungs
- Systemic circulation takes blood to and from the rest of the body
12
Q
Differentiate an atrium and a ventricle.
A
- Atrium: upper heart chamber that receives blood entering the heart
- Ventricle: lower heart chamber that pumps blood out of the heart
13
Q
How do pulmonary and systemic circulation differ in terms of resistance and pressure?
A
- Pulmonary: low pressure, low resistance
- Systemic: high pressure, high resistance
14
Q
What is pressure?
A
The force exerted on the vessel walls
15
Q
What is resistance?
A
The opposition to blood flow
16
Q
Why does blood flow (mechanistic)?
A
Liquids and gases flow down pressure gradients from regions of HIGHER pressure to regions of LOWER pressure
17
Q
Where is the highest pressure in vessels of the cardiovascular system?
A
In the aorta and systemic arteries (as they receive blood from the left ventricle)
18
Q
Where is the lowest pressure in vessels of the cardiovascular system?
A
Venae cavae, just before they empty into the right atrium
19
Q
What is peripheral resistance?
A
Resistance to blood flow imposed by the force of friction between blood and the walls of its vessels
20
Q
What are factors that influence peripheral resistance?
A
- Blood viscosity (thickness as a fluid)
- Diameter of arterioles
- Vasomotor mechanism
21
Q
What is the effect of plasma protein concentration on blood viscosity?
A
High plasma protein concentration increases blood viscosity
22
Q
What is the effect of hematocrit on blood viscosity?
A
High hematocrit (%RBCs) can increase blood viscosity
23
Q
What conditions may alter blood viscosity?
A
- Anemia
- Hemorrhage
- Other abnormal conditions
24
Q
What is a vasomotor mechanism?
A
- Muscles in walls of arterioles may constrict (vasoconstriction) or dilate (vasodilation)
- Changes the diameter of the arteriole
25
What mechanism is ideal for regulate blood pressure and flow? Why?
- Vasomotor mechanism
| - Because small changes in blood vessel diameter cause large changes in resistance
26
What characteristic of arterioles allows them to constrict or dilate to change the amount of resistance to blood flow?
Their muscular coat
27
How does peripheral resistance help determine arterial pressure?
By controlling the amount of blood that runs from the arteries to the arterioles
28
What are the effects of increase peripheral resistance?
- Decreased arteriole runoff
| - Leads to higher arterial pressure
29
Where can an increase in peripheral resistance occur?
- Locally (i.e. in one organ)
| - Or the total peripheral resistance may increase (raising systemic arterial pressure)
30
Which side of the blood performs more work? Why?
- The left side
| - Because it pumps into a longer high resistance system
31
What controls blood flow? How many are there?
- Pressure operated heart valves
| - There are four one-way heart valves
32
What is the heart encased in? What is inside?
- Tough membranous sac
- Pericardium
- Pericardial fluid is inside
33
What is the function of pericardial fluid?
Lubricates the external surface of the heart as it beats within the sac
34
What is the heart itself mostly composed of? What is it covered with?
- Myocardium (cardiac muscle)
| - Thin outer and inner layers of epithelium and connective tissue
35
What does the right atrium receive blood from and send blood to?
- Venae cavae
| - Right ventricle
36
What does the right ventricle receive blood from and send blood to?
- Right atrium
| - Lungs
37
What does the left atrium receive blood from and send blood to?
- Pulmonary veins
| - Left ventricle
38
What does the left ventricle receive blood from and send blood to?
- Left atrium
| - Body except for lungs
39
What does the venae cavae receive blood from and send blood to?
- Systemic veins
| - Right atrium
40
What does the pulmonary trunk (artery) receive blood from and send blood to?
- Right ventricle
| - Lungs
41
What does the pulmonary veins receive blood from and send blood to?
- Veins of the lungs
| - Left atrium
42
What does the aorta receive blood from and send blood to?
- Left ventricle
| - Systemic arteries
43
What are the two sets of valves called?
- Atrioventricular valves
| - Semilunar valves
44
What happens to the AV valve when a ventricle contracts?
Blood pushes against the bottom side of its AV valve, and forces it upwards in a closed position
45
What is the valve that separates the right atrium and ventricle called?
Tricuspid valve
46
What is the valve that separates the left atrium and ventricle called?
Bicuspid valve (mitral valve)
47
What does the aortic valve separate?
The left ventricle and the aorta
48
What does the pulmonary valve separate?
The right ventricle and the pulmonary trunk
49
Where are the semilunar valves located?
At the junction where the major arteries leave the ventricles
50
What are the chordae tendinae?
Collagenous cords that prevent the AV valves from being pushed back into the atria during ventricular contraction
51
What is the function of the papillary muscles?
Provide stability for the chordae, but they cannot actively open and close the AV valves
52
When do the AV valves let blood flow from the atria to the ventricles?
During ventricle fillings when atrial pressure exceeds ventricular pressure
53
Which AV valve is bicuspid? Which is tricuspid?
- Left: bicuspid
| - Right: tricuspid
54
How many cusps do semilunar valves have?
3
55
When are semilunar valves forced open?
- When the left and right ventricular pressure exceeds the pressure in the aorta and the pulmonary trunk
- During ventricular contraction and emptying
56
When do semilunar valves close?
When pressure in the ventricle falls below the aortic and pulmonary pressure
57
What are the three layers to the heart wall?
- Endocardium: inner
- Myocardium: middle
- Epicardium: external
58
Which cell type makes up the majority of cardiac muscle cells?
- Contractile cells (99%)
- They do the PUMPING
- They do not initiate their own action potential
59
Where does the signal for contraction originate from?
- Autorhythmic cells
- They do NOT contract
- They are responsible for initiating and conduction AP responsible for contraction of the working cells
60
Name the four major structures that compose the conduction system of the heart and contain specialized cells for conduction of action potential but NOT contraction.
- Sinoatrial node (SA node)
- Atrioventricular node (AV node)
- AV bundle (bundle of His)
- Purkinje system
61
Where do action potentials originate from the heart?
| Where is it?
- Sinoatrial node (SA node)
- In the right atrial wall
- Specialized pacemaker cells in the node possess an intrinsic rhythm
62
Which section of the heart sets the pace of the heartbeat? What happens if it malfunctions?
- SA node
| - Other autorhythmic cells in the AV node or ventricles take control of heart rate
63
What three criteria must be satisfied to assure coordinated and efficient pumping by the spread of the action potential?
1. Atrial excitation and contraction must be COMPLETE before ventricle contraction
2. Excitation of cardiac muscle fibers must be coordinated
3. The pair of atria and ventricles must contract together
64
What allows for complete ventricle filling?
Atrial excitation and contraction must be COMPLETE before ventricle contraction
65
What does the coordinated excitation of cardiac muscle fibers ensure?
That each heart chamber contracts as a unit to pump all the blood out
66
Why must the pair of atria and ventricles contract together?
To permit synchronized pumping of blood into the pulmonary and systemic circulation
67
What does the AV node allow?
Slows the action potential from the SA node to allow complete contraction of both atrial chambers before the impulse reaches the ventricles
68
What happens to conduction velocity after the AV node?
Velocity increases as the impulse is relayed through the AV bundle into the ventricles
69
What structures conduct the impulses throughout the muscles of both ventricles, stimulating them to contract almost simultaneously?
- Right and left branches of the bundle fibers
| - Purkinje fibers
70
Describe the mechanism of electrical conduction in the heart. This mechanism is IMPORTANT to know.
1. SA node depolarizes
2. Electrical activity goes rapidly to AV node via internodal pathways
3. Depolarization spreads more slowly across the atria (conduction slows through the AV node)
4. Depolarization moves rapidly through ventricular conducting system to the apex of the heart
5. Depolarization wave spreads upward from the apex
71
How do cardiac autorhythmic cells differ from nerve and skeletal muscle cells?
- Nerve and skeletal muscle: the membrane remains at constant RMP unless the cell is stimulated
- Cardiac ARC: do NOT have a resting membrane potential; they display pacemaker activity
72
How do cardiac autorhythmic cells initiate action potentials? How do nerve and skeletal muscle cells initiate action potentials?
- Cardiac ARC: repeated cycles of drift and fire (either contracts or not)
- Nerve and skeletal muscle: each motor unit contracts independently
73
What is the function of the septum?
To separate low oxygen blood (right) from high oxygen blood (left)
74
Which ventricle is larger?
The left since it pumps blood throughout the rest of the body (systemic circulation)
75
What are the three areas in the body that contain portal vein systems?
- Hepatic portal vein
- Kidneys
- Hypothalamus to the anterior pituitary
76
Describe the circulatory system components in terms of high to low blood pressure.
- Aorta
- Arteries
- Arterioles
- Capillaries
- Venules
- Veins
- Venae cavae
77
Explain how a runner could have a stroke or a heart attack.
- If you are extremely dehydrated, you increase the thickness of the blood
- Increases peripheral resistance
78
What muscle controls blood pressure and rate of flow?
Smooth muscle lining arteries
79
What does the body do to compensate for low blood pressure?
Increases the number of beats per minute
80
What does the chordae tendinae prevent?
Prevents the valves from being everted
81
Describe the movement of the depolarization.
1) SA node
2) AV node
3) Purkinje fibers (ventricles) down the AV bundle (also called bundle of His)
82
Why is it necessary to direct the electrical signal through the AV node?
- If electrical signals from the atria were conducted directly into the ventricles, they would start contracting at the top
- The blood would be squeezed downward and would become trapped in the bottom of the ventricles
- Also, slows down the transmission of action potential, which allows the atria to complete their contraction before ventricular contraction begins
83
What is the function of the AV node delay?
Allows the atria to complete their contraction before ventricular contraction begins
84
What happens if the SA node can no longer drive the heart rate? What can cause this to happen?
- The AV node drives the heart rate instead
| - Tissue death from myocardial infarction, inadequate blood supply, ectopic focus (overconsumption of caffeine)
85
What happens during ectopic focus?
- The heart rate is driven by Purkinje fibers, which are going much faster than the SA node
- Caused by caffeine, anxiety, lack of sleep
86
What do the intercalated discs couple?
The ARC cells and the contractile cells
87
Which cells do not display a resting potential?
Cardiac ARC cells
88
What do cardiac ARC cells display instead of a RMP?
Pacemaker activity
89
What is pacemaker activity?
- The membrane potential of cardiac ARC cells slowly depolarizes or can be thought to drift between action potentials until threshold is reached
- Through repeated cycles of drift and fire, these cells cyclically initiate action potentials
90
Do skeletal or cardiac muscles contract independently?
- Skeletal: independent motor units
| - Cardiac: the HEART either contracts or not
91
What is the membrane potential's slow drift to threshold caused by? What is it PRIMARILY driven by?
- By a cyclical DECREASE in passive outward flux of K+
- By a constant inward leak of Na+ and Ca2+
- PRIMARILY driven by changing the permeability of potassium
92
What does the peak of membrane potential signal cardiac muscle cells to do?
Opening of the K+ channel, allowing K+ to escape the inside of the cells and reduce the action potential
93
Gap junctions are areas of ___ electrical resistance.
low
94
Can cardiac cells generate electrical pulses without any nervous stimulation?
Yes, some
95
Name three differences between cardiac and skeletal muscle.
- Cardiac: not-multinucleated
- Cardiac: has intercalated discs
- Skeletal: triad, Cardiac: diad
96
Which components of the heart form separate functional syncytium?
The atria and ventricles
97
Which cells initiate the action potential of cardiac CONTRACTILE cells? How do they differ from ARC cells?
- Nodal pacemaker cells
| - Differs in ionic mechanisms
98
Which cells exhibit a plateau phase of action potential? Why?
- Nodal pacemaker cells
| - To allow for the blood to fully empty and fill into the chambers
99
What is the RMP of cardiac contractile cells? What is the threshold?
- -90 mV
| - -70mV
100
Describe how cardiac contractile cells initiate an action potential.
1) Cells are stimulated by ion movement from the ARC cells
2) Increase in permeability of sodium (moves VERY quickly)
3) Gates of sodium closes, and calcium moves in
4) Calcium gates close and potassium gates out (K+ out fast)
101
What allows for the prolonged plateau phase of action potential?
- Calcium gates opening, allowing calcium to move in slowly
| - Decrease in K+ permeability
102
What is the long refractory period of cardiac muscle cells due to?
Due to Na+ channels that are inactivated until the membrane has repolarized
103
What does the long refractory period of cardiac muscle cells allow?
To avoid tetanus
104
The heart is innervated by what divisions of the nervous system?
- Sympathetic
- Parasympathetic
- Both are from the autonomic nervous system
105
How does the nervous system relate to heart rate?
- Nervous stimulation is NOT required to initiate contraction
- But, it can modify heart rate
106
How does the parasympathetic and sympathetic nervous system bring about their effects on the heart?
By altering the activity of the cAMP second messenger system
107
What is the parasympathetic nerve to the heart? What does it primarily affect?
- Vagus nerve
| - Atrium and the SA and AV nodes
108
What is the effect of the parasympathetic nervous system on the heart?
Decrease heart rate (inhibitory)
109
How does the parasympathetic nervous system decrease heart rate?
- Releases acetylcholine, which increases the permeability of the K+ channels (more K+ out of the cells)
- Hyperpolarizing effect
110
What is the effect of the parasympathetic nervous system on blood vessels?
Vasodilatation
111
What is the effect of the sympathetic nervous system? When is it needed?
- When there is a need for greater blood flow
| - Stimulatory effect (increases heart rate)
112
How does the sympathetic nervous system increase heart rate?
- Releases norepinephrine and stimulates the SA node
| - Accelerates inactivation of K+ channels (less able to leave cells)
113
What is the effect of the sympathetic nervous system on blood vessels?
Vasoconstriction
114
Where are the baroreceptors located in the heart?
- Carotid (carotid sinus)
| - Aortic
115
What is the function of cardiac baroreceptors?
- Send nerve fibers to the cardiac control center (medulla oblongata)
- Oppose changes in blood pressure by adjusting the HEART RATE
116
Describe what happens when your heart rate increases cause you are scared.
1) Increase in blood pressure
2) Baroreceptors feed information via cranial nerves to the medulla oblongata
3) Correction signal via cranial nerve; releases acetylcholine on SA node
4) Decreases the heart rate
5) Negative feedback loop
117
What does the cranial nerve send out when there is an increase in heart rate? What does that affect?
- Acetylcholine
| - SA node
118
How do calcium channels in autorhythmic cells differ from contractile cells?
- ARC cell channels open rapidly when the membrane potential reaches -50mV and close when it reaches +20mV
- Contractile cell Ca2+ channels are slower and do not open until the membrane has depolarized fully
119
What happens to the action potential of a myocardial autorhythmic cell if tetrodotoxin (blocks voltage-gated Na+ channels) is applied to the cell?
Nothing will happen, because there are no voltage-gated Na+ channels in the cell
120
During atrial filling, is pressure in the atrium higher or lower than pressure in the venae cavae?
The atrium has lower pressure than the venae cavae
121
Which is NOT a function of the cardiovascular system?
A) transport oxygen absorbed in the lungs to cells of the body
B) remove wastes from the body
C) facilitate movement of materials from cell to cell
D) transport nutrients absorbed from the gastrointestinal tract to cells of the body
B) remove wastes from the body
122
The effect of parasympathetic input to the heart is to __________.
A) open additional potassium channels in pacemaker cells
B) do nothing
C) promote calcium entry in pacemaker and contractile cells
D) decrease force of ventricular contraction
A) open additional potassium channels in pacemaker cells
123
When threshold is reached at the SA node (an autorhythmic cell), what channels open, causing further depolarization of the membrane?
A) Sodium
B) Potassium
C) Slow calcium
D) Fast calcium
D) Fast calcium
124
The myocardium is composed of
A) an outer fibrous layer and an inner serous layer
B) cardiac muscle tissue
C) a simple squamous epithelium and a layer of areolar connective tissue
D) both b and c
B) cardiac muscle tissue
125
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An ECG produces a composite tracing of all ____________ generated by myocardial cells.
A) muscle impulses
B) nerve impulses
C) muscle contractions
D) metabolic activity
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A) muscle impulses
