231 Physiology Term 2 Learning Objectives 1 & 2 Flashcards
Autonomic Nervous System and Cardiovascular System
1
Q
What are the two divisions of the autonomic nervous system?
A
Sympathetic and parasympathetic systems
2
Q
Define the parasympathetic sy.stem.
A
This is the “rest and digest” system within the ANS. It is involved in the normal daily activities.
3
Q
Define the sympathetic system.
A
This is the “fight or flight” system within the ANS. It involves thing like heart rate, sweat, pulse, etc.
4
Q
True or False: Human can control their autonomic nervous system
A
False. The autonomic nervous system, along with the parasympathetic and sympathetic components, are involuntary.
5
Q
True or False. The parasympathetic system is more complex than the sympathetic system.
A
False. The sympathetic system is more complex.
6
Q
Name some functions that are affected by the sympathetic and parasympathetic systems.
A
Think of the parasympathetic division as the D division [digestion, defecation, and diuresis (urination)], and the sympathetic division as the E division (exercise, excitement, emergency, embarrassment)
7
Q
Where does the parasympathetic system arise from?
A
Most come from the cranial nerves with a few from the sacral section of the spinal cord.
8
Q
Which cranial nerves are involved with the parasympathetic system?
A
III - oculomotor nerves
VII - facial nerves
IX - glossopharyngeal nerves
X - vagus nerves
9
Q
Which nerve account for most of the preganglionic parasympathetic fibers in the body?
A
The vagus nerves; the two nerves account for about 90%
10
Q
What section of the sacral region is involved with the parasympathetic nervous system?
A
S2 - S4
11
Q
True or False. The sacral part of the parasympathetic division serves the pelvic organs and the distal half of the large intestine.
A
True
12
Q
In general what does the ANS innervate (what are the effectors)?
A
The ANS innervates cardiac and smooth muscle and glands.
13
Q
At the second synapse in the parasympathetic, what is the neurotransmitter?
A
Acetylcholine
14
Q
At the second synapse in the parasympathetic, what is the receptor?
A
The muscarinic acetylcholine receptor
15
Q
What nerves are involved in the sympathetic system?
A
Spinal nerves including all thoracic nerves and L1 and L2
16
Q
In what systems is smooth muscle commonly found?
A
Reproductive, respiratory, digestive and urinary
17
Q
What system controls skeletal muscle?
A
Somatic nervous system
18
Q
What is the location of the ganglia in the parasympathetic nervous system?
A
Terminal ganglia are within the visceral organ (intramural) or close to the organ served.
19
Q
Define nerve.
A
A bundle of axons.
20
Q
How many synapses are there in the pathway for the parasympathetic system?
A
2
21
Q
What neurotransmitter is released at the synapses of the parasympathetic system?
A
acetylcholine
22
Q
Define ganglion.
A
Collection of nerve cell fibers.
23
Q
What is the importance of the second synapse ?
A
Produces the action potential that can be excitatory (contracts the muscle) or inhibitory (relaxes the muscle).
24
Q
T or F: The action (inhibitory or excitatory) can change at a location.
A
False. It is always one or the other and it stays constant.
25
What is the receptor on skeletal muscle?
Nicotinic.
26
What neurotransmitter is the nicotinic receptor specific for?
acetylcholine
27
Name the receptor that is present at the 1st synapse in the parasympathetic system.
nicotinic receptor
28
Name the receptor that is at the 2nd synapse of the parasympathetic system.
muscarinic receptor
29
True or False: The sympathetic system is is identical to the parasympathetic system at the 1st synapse.
True
30
What is the neurotransmitter at the 2nd synapse in the sympathetic division.
norepinephrine
31
What is the receptor at the 1st synapse in the sympathetic division?
Nicotinic
32
List three different receptors that can be found at the 2nd synapse in the sympathetic division.
Alpha 1 receptor, Beta 1 receptor, Beta 2 receptor
33
List 3 differences between the parasympathetic and sympathetic divisions.
- 1 Sites of origin. Parasympathetic fibers are craniosacral—they originate in the brain (cranium) and sacral spinal cord. Sympathetic fibers are thoracolumbar—they originate in the thoracic and lumbar regions of the spinal cord.
2 Relative lengths of their fibers. The parasympathetic division has long preganglionic and short postganglionic fibers. The sympathetic division has the opposite condition—the preganglionic fibers are short and the postganglionic fibers are long.
3 Location of their ganglia. Most parasympathetic ganglia are located in or near the visceral effector organs. Sympathetic ganglia lie close to the spinal cord.
4 Fight or flight versus rest and digest.
34
Which structures are only innervated by the sympathetic nervous system?
- Sweat glands (both eccrine and apocrine)
- The hair-raising arrector pili muscles of the skin
- Smooth muscle in the walls of all arteries and veins, both deep and superficial (This will be a key point for you to remember when you study the cardiovascular system.)
35
In the case of the sympathetic system being stimulated which neurotransmitter is involved at the second synapse on the heart?
Norepinephrine -often abbreviated as NE
36
In the case of the sympathetic system being stimulated what receptor is involved at the second synapse on the heart?
Beta 1
37
In the case of the sympathetic system being stimulated what will the effect be on the heart?
An increased heart rate and strength of contraction.
38
Define cholinergic fibers.
Those that release ACh—include (1) all ANS preganglionic axons and (2) all parasympathetic postganglionic axons at synapses with their effectors.
39
Define adrenergic fibers.
Those that release norepinephrine—include the majority of sympathetic postganglionic axons. An exception is sympathetic postganglionic fibers that secrete ACh onto sweat glands.
40
Describe the parasympathetic effects on the eye.
- parasympathetic cholinergic excitatory effect
- contracts smooth, circular muscle in the iris
- acetylcholine
- constricts pupil
- bright light would cause this, letting less light in
41
Describe the parasympathetic effect on the bronchioles.
- parasympathetic cholinergic excitatory effect
- goes to the smooth muscle in the bronchioles
- acetylcholine
- muscarinic receptor
- will contract the muscle
- enacted when there is less metabolic demand
42
Describe the parasympathetic effect on the GI tract.
- parasympathetic cholinergic excitatory effect
- goes to the smooth muscle (circular smooth muscle)
- contracts the muscle
- acetylcholine
- muscarinic receptor
- increases peristalsis (motility of food or churning of food)
43
Describe the parasympathetic effect on the bladder.
- parasympathetic cholinergic excitatory effect
- smooth muscle
- acetylcholine
muscarinic receptor
- causes muscle to contract
- causes urination/pushes urine out
44
Describe the parasympathetic effect on the GI sphincter.
- parasympathetic cholinergic inhibitory effect
- circular muscle
- acetylcholine
- muscarinic receptor
- relaxes the muscle
- allows food to move through the GI tract
45
Describe the parasympathetic effect on the bladder sphincter.
- located between the bladder and the urethra
- acetylcholine
- muscarinic receptor
- relaxes the sphincter
- use when urinating
46
Ninety percent of all the preganglionic parasympathetic fibers are found in the __________
Vagus nerves. The two vagus nerves account for 90% of the preganglionic parasympathetic fibers in the body.
47
Why is the effect of acetylcholine and norepinephrine NOT consistently excitatory or inhibitory to a given target tissue?
The action of any neurotransmitter depends on the receptor to which it binds. Each autonomic neurotransmitter binds with two or more kinds of receptors, which allows it to exert different effects at different body targets.
48
The sacral part of the parasympathetic division serves which of the following organs?
a) the pancreas
b) the gallbladder
c) the distal half of the large intestine
d) the stomach
e) the kidney
c) the distal half of the large intestine
49
What are the two Ach receptors?
nicotinic and muscarinic
50
When ACh binds to a nicotinic receptor, what kind of effects always results?
Stimulatory/excitatory
51
What are the two major classes of andrenergic receptors?
Alpha and beta
52
What neurotransmitter binds with alpha and beta receptors?
norepinephrine (or epinephrine)
53
Would you find nicotinic receptors on skeletal muscle? Smooth muscle? Eccrine sweat glands? The adrenal medulla? CNS neurons?
You would find nicotinic receptors on skeletal muscle and the hormone-producing cells of the adrenal medulla, but not on smooth muscle or glands. Virtually all types of receptors (including nicotinic receptors) are also found in the CNS.
54
What is the parasympathetic effect on the iris?
Stimulates sphincter pupillae muscles; constricts pupils
55
What is the sympathetic effect on the iris?
Stimulates dilator pupillae muscles; dilates pupils
56
What is the parasympathetic effect on sweat glands?
None; there is no innervation to the parapsympathetic
57
What is the sympathetic effect on sweat glands?
Stimulates copious sweating
58
Describe the parasympathetic, inhibitory response in the heart.
- ACh
- Muscarinic receptor
- causes cardiac muscle to relax and slows the heart rate down
- takes longer for the cardiac muscle to create an action potential
59
Describe the sympathetic adrenergic alpha 1 excitatory effect on the iris.
- norepinephrine attaches to the alpha 1 receptor
- radial smooth muscle will contract
- pupil will dilate
- fight or flight/allows more light in
60
Describe the sympathetic adrenergic alpha 1 excitatory effect on the GI tract sphincter.
- norepinephrine attaches to alpha 1 receptor on smooth muscle
- muscle contracts
- sphincter constricts (no food passes through - "flight")
61
Describe the sympathetic adrenergic alpha 1 excitatory effect on the bladder sphincter.
- circular smooth muscle of sphincter
- norepinephrine
- smooth muscle contracts
- sphincter closes
- result is no urination
BUT: there is another sphincter with skeletal muscle; can't prevent peeing forever!
62
List three examples of organs that don't have dual innervation.
- blood vessels
- arrector pili muscles
- kidney
- adrenal medulla
- sweat glands
63
Describe the sympathetic adrenergic beta 1 excitatory effect on the heart.
- norepinephrine binds to Beta 1 receptor
- cardiac muscle
- contracts cardiac muscle
- increases heart rate (contracts more often)
- also increases the strength of the contraction
- high energy, stressful situations
64
Describe the sympathetic adrenergic beta 2 inhibitory effect on the digestive tract.
- beta 2 receptor
- norepinephrine
- circular, smooth muscle
- causes it to relax
- won't be digesting; no peristalsis
65
Describe the sympathetic adrenergic beta 2 inhibitory effect on the lungs.
- norepinephrine
- smooth muscle will relax
- bronchioles are dilated
- allows more oxygen in for high energy situations
66
What is an example of a cooperative effect on the autonomic nervous system?
In the external male genitalia. A cooperative effect means both systems are working to achieve the same result.
Parasympathetic stimulation dilates blood vessels in the external genitalia, producing the erection of the male penis. Ach, muscarinic, inhibitory effect,
Sympathetic stimulation then causes ejaculation of semen by the penis. Smooth muscle, NE, alpha 1 receptor, excitatory.
67
Besides the external genitalia, what other organ has the sympathetic/parasympathetic cooperative influences?
Salivary glands
68
Explain how the sympathetic division mediates reflexes that regulate body temperature.
Applying heat to the skin causes blood vessels in that area to dilate reflexively. When systemic body temperature rises, sympathetic nerves (1) dilate the skin’s blood vessels, allowing heat to escape from skin flushed with warm blood, and (2) activate the sweat glands to help cool the body. When body temperature falls, skin blood vessels constrict, preventing heat loss from the skin.
69
What roles does the sympathetic system have with the kidneys?
Sympathetic impulses stimulate the kidneys to release renin, an enzyme that causes the formation of potent blood pressure–increasing hormones.
70
Which system exerts short-lived, highly localized control over its effectors?
the parasympathetic system
71
Which system creates longer effects?
the sympathetic nervous system
72
What system is the adrenal gland controlled by?
sympathetic
73
How many synapses are there with the adrenal gland?
one - no second neuron/2nd synapse; spinal nerve goes directly to the adrenal gland
74
What does the adrenal gland produce?
epinephrine (80%) and norepinephrine (20%). These are hormones when coming from the gland and are released into the bloodstream. It will therefore be slower and the effect lasts longer and is less specific as to location.
75
Define a cooperative effect.
When both systems are trying to achieve the same result,
76
What system is used to raise and lower blood pressure?
Sympathetic system is the only one that affects the smooth muscle in the blood vessels. To increase blood pressure, blood vessels in the whole body would constrict. Alpha 1 receptor and NE. Would need to turn off the sympathetic effect to make the blood vessels relax.
77
What system of the ANS controls the uterus?
The sympathetic system. Can cause both contraction and relaxation.
78
What largely influences the contraction of the uterus?
hormones
79
What 2 actions can medications have on the effects found in the ANS systems?
1. Block the receptor
| 2. bind to the receptor and mimic the neurotransmitter
80
Describe what happens with the ANS in the case of asthma and your medication choices. Which one is the optimal choice?
Parasympathetic: ACh, muscarinic, smooth muscle in bronchioles contracts
Sympathetic: NE, Beta 2, smooth muscle relaxes
We want the sympathetic effect.
Choices:
1. block ACh at muscarinic receptor
2. Mimic NE at the receptor
#2 is the better answer
81
How does the sympathetic nervous system factor in to high blood pressure?
- Alpha 1, smooth muscle of the blood vessels, NE
| - Beta 1, cardiac muscle, NE
82
What medication options would apply to treating high blood pressure based on the two main ways that medication work on the ANS (block receptor or mimic neurotransmitter)? Which one is best?
1) Block NE at alpha 1 receptor. Smooth muscle in blood vessels would relax and lower blood pressure.
2) Block Beta 1 receptor, NE can't bind, affects cardiac muscle, decreased heart rate and decreased strength of contraction. (BEST WAY)
3) Attach to muscarinic receptor and mimic ACh; slows down the heart rate.
83
What is the main function of the cardiovascular system?
Transport/circulate blood throughout the body.
84
Why do you need heart valves to close before ventricle relax?
Prevent backflow
85
List the four main valves in the heart.
- Tricuspid
- Mitral
- Aortic
- Pulmonary
86
What are the two circuits of the body called with regards to the cardiovascular system?
systemic circuit
| pulmonary circuit
87
Name the valve that has just two cusps.
Mitral valve or bicuspid valve
88
Which side of the heart acts as the pulmonary pump? The systemic pump?
The right side of the heart acts as the pulmonary pump, whereas the left acts as the systemic pump.
89
Which of the following statements are true? (a) The left ventricle wall is thicker than the right ventricle wall.
(b) The left ventricle pumps blood at a higher pressure than the right ventricle.
(c) The left ventricle pumps more blood with each beat than the right ventricle. Explain.
(a) True. The left ventricle wall is thicker than the right. (b) True. The left ventricle pumps blood at much higher pressure than the right ventricle because the left ventricle supplies the whole body, whereas the right ventricle supplies only the lungs.
(c) False. Each ventricle pumps the same amount of blood with each beat. If this were not true, blood would back up in either the systemic or pulmonary circulation (because the two ventricles are in series).
90
Where is the sinoatrial (SA) node located?
The crescent-shaped sinoatrial node is located in the right atrial wall, just inferior to the entrance of the superior vena cava.
91
How many impulses does the SA node generate per minute?
about 75
92
Why does the SA node set the rate for the heart?
SA node sets the pace for the heart as a whole because no other region of the conduction system or the myocardium has a faster depolarization rate. For this reason, it is the heart’s pacemaker, and its characteristic rhythm, called sinus rhythm, determines heart rate.
93
Where does the impulse pause in the heart? Why?
At the AV node, the impulse is delayed for about 0.1 second, allowing the atria to respond and complete their contraction before the ventricles contract. Ensures that atria and ventricles don't contract at the same time.
94
What is the SA node known as? What is it known to do?
It is called the pacemaker component and it sets the basic rhythm of the heart.
95
In the septum, what transmits the message?
AV bundle
96
What do the AV bundles branch into?
bundle branches and then further into subendocardial conducting network
97
What is happening to the atria when message is in the network?
atria are relaxing and the ventricles will be ready to contract
98
How would heart rate change if controlled by SA node, or AV node, or the subendocardial conducting network.
The SA node normally drives the heart at a rate of 75 beats per minute. Without SA node input, the AV node would depolarize only about 50 times per minute. Without input from the AV node, the atypical pacemakers of the AV bundle and the subendocardial conducting network would depolarize only about 30 times per minute. Note that these slower pacemakers cannot dominate the heart unless faster pacemakers stop functioning.
99
Which nerve primarily affects the SA node?
the vagus nerve
100
Cardiac muscle needs an ______________ to contract.
an action potential
101
In an action potential in the SA node, what causes depolarization?
Ca2+ influx through CA2+ channels. This is different than the typical.
102
What is unusual about the cardiac action potential?
It has a much longer duration caused by the plateau effect
103
What unusual ion causes this effect?
Calcium. Calcium ions move into the cell as potassium ions move out
104
What is the advantage of a long action potential in the heart?
It causes a very powerful muscle contraction with resulting huge tension.
105
Define systole.
Refers to these periods of contraction
106
Define diastole.
Refers to periods of relaxation.
107
Define cardiac cycle.
includes all events associated with the blood flow through the heart during one complete heartbeat—atrial systole and diastole followed by ventricular systole and diastole.
108
What are heart sounds often described as?
often described as lub-dup, are associated with the heart valves closing.
109
The second heart sound is associated with the closing of which valve(s)?
The second heart sound is associated with the closing of the semilunar valves.
110
Why does it have a pacemaker potential?
Neurons in the pacemaker need to continue generating action potentials -rhythmic firing- that causes the heart to beat even if they receive no external input
111
What causes gradual depolarization in the AP in the SA node?
Potassium channels are closing, just a few Na+ channels start to open and Ca2+ also starts to open.
112
How is the heart rate affected by the parasympathetic division?
It goes to the SA node, releases ACh which binds to muscarinic receptors. This has an inhibitory effect and causes the heart rate to slow down.
113
How can we influence heart rate at SA node.
Can influence the pacemaker potential
114
How would you slow down the pacemaker potential?
We want it to take longer. Open some potassium channels. Potassium would leave the cell and make it more negative, which will cause it to take longer to hit threshold.
115
What happens at each phase of the action potential in the SA node?
1 - Pacemaker potential
Slow depolarization is because of the opening of sodium channels and the closing of K + channels. The membrane potential is never a flat line.
2 - Depolarization
The action potential begins when the pacemaker potential reaches threshold (-40MV)
Depolarization is due to calcium influx through voltage gated calcium channels
3 - Repolarization
Repolarization is due to CA 2+ channels inactivating and potassium channels opening. This allows for potassium to rush out, which brings the membrane potential back to its negative voltage.
116
Q6. Which division of the ANS controls the diameter of blood vessels? What does it do to blood vessel diameter, give the neurotransmitter and receptor and how would you achieve the opposite effect? [2]
The sympathetic division controls the diameter of blood vessels. It reduces blood vessel diameter. It releases norepinephrine which binds to an Alpha 1 receptor. To achieve the opposite effect you would need to turn off the sympathetic response.
117
A patient is having a difficult time defecating (is unable to defecate). When developing a drug to help solve this problem which receptors would you target and why?
Depending upon the issue (poor peristalsis within the GI tract versus GI sphincter malfunction), you can look at affecting receptors within the GI tract or the GI tract sphincters as follows:
GI tract sphincter
Target the muscarinic receptors and mimic ACh to have the smooth muscle of the sphincters relax, allowing for defecation
Target the Alpha 1 receptor to block the NE to prevent/reduce the contraction of smooth muscle and the constriction of the GI sphincter
GI tract
Target the muscarinic receptor and mimic ACh to stimulate more muscle contraction and peristalsis
Target the Beta 2 receptor and prevent NE from binding; this will prevent/reduce the relaxing of smooth muscle and its inhibition of peristalsis
118
Compare (2 similarities) and contrast (2 differences) the effects of the two divisions of the ANS at the second synapse in terms of the lungs.
2 similarities
Both the sympathetic and parasympathetic divisions affect the smooth muscle in the bronchioles
Both divisions affect the flow of oxygen through the bronchioles that address the activity demands of the body.
2 differences
The parasympathetic division uses a muscarinic receptor and the sympathetic division uses an Beta 2 receptor
The parasympathetic division causes the smooth muscle to contract and the bronchioles to constrict, restricting air flow, while the sympathetic causes the smooth muscle to relax and the bronchioles to dilate, allowing more oxygen in.
119
Define SA node.
Specialized myocardial cells located in the right atrium, the SA node acts as the pacemaker and sets the basic rhythm of the heart. If the SA node is in control, the heart rate will be on average about 75 beats per minute.
120
Define AV node
Specialized cardiac cells in the right atrium. transmits message to AV bundle. Connected to the ventricles cia specialized cells in the septum.
121
How does the sympathetic system influence the SA node?
- use NE at the Beta 1 receptor
- excitatory response
- we want the pacemaker potential to happen faster and more quickly hit threshold
- open more sodium channels and more sodium comes in
122
List some differences between the SA node action potential and the ventricular muscle cell action potential.
- Depolarization is more rapid in the ventricular muscle cell AP
- The ventricular muscle cell has a plateau effect, representing a longer absolute refractory period. The SA node AP does not have this.
- The SA node AP does not get as negative at the membrane potential at its most negative as the ventricular cell membrane potential. This is due to the pacemaker potential effect, that the ventricular muscle cell does not have.
123
Why do we think the ventricular muscle cell has a resting membrane potential of -90 mV?
Due to leaky potassium.
124
What do muscles need in order to contract?
calcium
125
Why would we want a long absolute refractory period in a ventricle contractile cell?
Need to ensure that the APs can't summate, resulting in long, powerful contractions. It would completely mess up the flow of blood. The ventricle needs to relax in order to fill with blood.
126
In cardiac muscle, how does calcium come in?
through the extracellular fluid
127
Name the waves of the ECG.
P wave, QRS complex, T wave
128
What is happening during the P wave?
Atrial depolarization. The first, the small P wave, lasts about 0.08 s and results from movement of the depolarization wave from the SA node through the atria. Approximately 0.1 s after the P wave begins, the atria contract.
129
What is happening during the QRS complex?
Ventricles are depolarizing. Average duration of the QRS complex is 0.08 s.
130
What is happening during the T wave?
Ventricle repolarization. The T wave, caused by ventricular repolarization, typically lasts about 0.16 s. Repolarization is slower than depolarization, so the T wave is more spread out and has a lower amplitude (height) than the QRS complex.
131
T or F: Atrial repolarization is clearly marked on ECG.
False. Atrial repolarization is hidden by the QRS complex.
132
Describe the sequence of depolarization and repolarization of the heart related to the ECG waves.
1. Atrial depolarization, initiated by the SA node, causes the P wave.
2. Atria contract.
3. With atrial depolarization complete, the impulse is delayed at the AV node.
4. Ventricular depolarization begins at the apex, causing the QRS complex. Atrial repolarization occurs.
5. Ventricular depolarization complete and ventricles contract.
6. Ventricular repolarization begins at apex, causing the T wave.
7. Ventricular repolarization is complete.
133
Describe what would an ECG would look like if the SA node were non functional.
In a junctional rhythm, the SA node is non functional. As a result:
- P waves are absent
- The AV node paces the heart at 40-60 beats per minute.
134
What happens when there is a second degree heart block?
The AV node fails to conduct some SA node impulses.
- As a result, there are more P waves than QRS waves
- In this case, there are usually two P waves for each QRS wave
135
What would you expect to see on an ECG during ventricular fibrillation?
Electrical activity is disorganized. Action potentials occur randomly throughout the ventricles. Results in chaotic, grossly abnormal ECG deflections.
136
When would you see ventricular fibrillation on a ECG>
In acute heart attack or after an electrical shock.
137
Cardiac muscle cannot go into tetany. Why?
Cardiac muscle cannot go into tetany because the absolute refractory period is almost as long as the contraction.
138
Describe the electrical event in the heart that occurs during each of the following: (a) the QRS complex of the ECG; (b) the T wave of the ECG; (c) the P-R interval of the ECG.
(a) The QRS wave occurs during ventricular depolarization. (b) The T wave of the ECG occurs during ventricular repolarization. (c) The P-R interval of the ECG occurs during atrial depolarization and the conduction of the action potential through the rest of the intrinsic conduction system.
139
Define cardiac output.
Amount of blood pumped out by each ventricle in one minute (mL/minute)
140
Define heart rate.
of time a heart contracts per minute.
141
Define stroke volume.
Amount of blood pumped out by a ventricle for one contraction.
142
Where are the aortic valve sounds heard best?
2nd intercostal space at right sternal amrgin
143
Where are the pulmonary valve sounds best heart?
2nd intercostal space at left sternal margin
144
Where are the mitral valve sounds heard?
Over heart apex (in 5th intercostal space) in line with middle clavicle.
145
Where are the tricuspid valve sounds heard?
In right sternal margin of 5th intercostal space.
146
An ECG provides information about (a) cardiac output, (b) movement of the excitation wave across the heart, (c) coronary circulation, (d) valve impairment.
B
147
The sequence of contraction of the heart chambers is (a) random,
(b) left chambers followed by right chambers,
(c) both atria followed by both ventricles,
(d) right atrium, right ventricle, left atrium, left ventricle.
C
148
The fact that the left ventricular wall is thicker than the right reveals that it
(a) pumps a greater volume of blood,
(b) pumps blood against greater resistance,
(c) expands the thoracic cage,
(d) pumps blood through a smaller valve.
B
149
In the heart, which of the following apply?
(1) Action potentials are conducted from cell to cell across the myocardium via gap junctions,
(2) the SA node sets the pace for the heart as a whole, (3) spontaneous depolarization of cardiac cells can occur in the absence of nerve stimulation,
(4) cardiac muscle can continue to contract for long periods in the absence of oxygen.
(a) all of the above,
(b) 1, 3, 4,
(c) 1, 2, 3,
(d) 2, 3.
C
150
Which 2 parameters affect cardiac output?
heart rate and stroke volume
151
If you increase End Diastolic Ventricular Volume you will ... Stroke volume
Increase
152
Give two ways that exercise, such as running, will increase End Diastolic Volume.
1: Contraction of skeletal muscle in your legs will force more blood back to the heart. 2: An increase in inspiration will allow more blood to return to the heart.
153
What is the cardiac output if heart rate is 75 beats per minute and stroke volume is 70 mL?
75 x 70 = 5.25 L/min (typical cardiac output)
154
What is the volume of blood for the average adult?
5L (every minute, your entire volume of blood travels through your heart)
155
What are some things you could do to increase the stroke volume?
1. Increase the strength of contraction
| 2. Increase venous return
156
How do you increase the strength of contraction?
1. Using the sympathetic nervous system. NE binds to Beta 1 receptor, more calcium channels open.
2. Also, hormone epinephrine would act in much the same way and increase contraction.
157
Define blood flow.
Blood flow is the volume of blood flowing through a vessel, an organ, or the entire circulation in a given period (ml/min).
158
Define blood pressure.
Force exerted by blood against a unit area of the blood vessel walls; differences in blood pressure between different areas of the circulation provide the driving force for blood circulation.
159
What does EDV refer to?
End of diastole. The amount of blood in the ventricle at the end of relaxation. This is when the ventricle is relaxing and filling up with blood.
160
List three factors that determine resistance in a vessel. Which of these factors is physiologically most important?
The three factors that determine resistance are blood viscosity, vessel length, and vessel diameter. Vessel diameter is physiologically most important.
161
What is the driving force that keeps blood moving?
The hydrostatic pressure gradient—the differences in blood pressure within the vascular system—provides the driving force that keeps blood moving, always from an area of higher pressure to an area of lower pressure, through the body.
162
When we decrease our heart rate using the _________ nervous system, it's going to ________ cardiac output and __________ blood pressure.
parasympathetic, decrease, decrease
163
List three ways that you can affect heart rate.
1) Use the parasympathetic system to decrease heart rate. ACh, muscarinic receptors, cardiac muscle.
2) Sympathetic system increases the heart rate. NE, Beta 1 receptor, cardiac muscle.
3) Activate the adrenal gland to produce the hormone epinephrine, which will increase your heart rate.
164
List three ways to alter your end diastolic volume.
1) Constrict veins using the sympathetic system, Alpha 1 receptor, NE, contract, squeeze more blood back).
2) Contract skeletal muscle (increase activity of the skeletal muscles). This will also squeeze veins.
3) Inspiration. Increase inspiration returns more blood.
165
How does inspiration work to increase end diastolic volume (EDV)?
When you breathe in, your diaphragm contracts and the volume, the space inside your thorax, increases and there is actually less pressure on the vein as it runs through your thoracic cavity. So you are going to lower pressure there. Your abdominal cavity has a higher pressure. And therefore the higher pressure in the abdominal cavity will push the blood back through your thoracic cavity and more blood will return to your heart.
166
What is a long-term way to increase venous return?
Increase blood volume
167
Which three hormones influence blood volume?
ADH, Aldosterone and ANP (atrial naturetic peptide)
168
Only 2 of these hormones will increase blood volume. Which 2?
ADH and Aldosterone
169
What kind of hormone is aldosterone and where is it produced?
A steroid hormone and it is produced in the adrenal glands
170
Explain how aldosterone works to affect blood volume.
Initially, blood pressure goes down > stimulates the sympathetic nervous system > stimulates the kidneys to produce renin > renin from the kidneys end up producing angiotensin II in the bloodstream > angiotensin II goes to the adrenal cortex > adrenal cortex produces aldosterone > aldosterone goes to the kidneys > causes the kidneys to reabsorb sodium > by osmosis, a reabsorption of water will follow > serves to increasing blood pressure
171
Which hormone causes blood volume to decrease? Provide a brief explanation of how it works to decrease blood volume.
ANP (atrial naturetic peptide) decreases blood volume. It comes from the heart. It goes to the kidneys, and it causes your kidneys to secrete more sodium, to excrete more sodium, so they lose more sodium and water will follow and blood volume will go down and then blood pressure will follow. Effectively does the opposite of aldosterone.
172
Do hormones act fast or slow relative to blood volume?
Slow
173
Define resistance.
Resistance is opposition to flow and is a measure of the amount of friction blood encounters as it passes through the vessels. Because most friction is encountered in the peripheral (systemic) circulation, well away from the heart, we generally use the term total peripheral resistance (TPR).
174
Define blood viscosity.
The internal resistance to flow that exists in all fluids is viscosity and is related to the thickness or “stickiness” of a fluid. The greater the viscosity, the less easily molecules slide past one another and the more difficult it is to get and keep the fluid moving.
175
What could change the viscosity of the blood?
Conditions such as polycythemia (excessive numbers of red blood cells) can increase blood viscosity and so resistance increases. On the other hand, if the red blood cell count is low, as in some anemias, blood is less viscous and total peripheral resistance declines. Can also change when you become dehydrated.
176
As adults, what is the main way of altering resistance?
Blood vessel diameter.
177
Which neurotransmitter is the main way of causing vasoconstriction? What receptor does it act on?
Norepinephrine. Alpha 1 receptor.
178
True or False: The pumping action of the heart generates blood flow. Pressure results when flow is opposed by resistance.
True
179
The _____________ offer the greatest resistance to blood flow.
Arterioles
180
True or false. Angiotensin II is a hormone.
False. It is an enzyme.
181
True or false. Aldosterone is a vasoconstrictor.
False. Angiotensin II, which activates the adrenal cortex to produce aldosterone, is the vasoconstrictor.
182
Where is blood pressure highest in the body?
Where the aorta comes out of the heart; the aortic arch.
183
Define baroreceptors.
They are nerve endings, like dendrites and are embedded in the smooth muscle. These stretch receptors are located in the carotid sinuses (dilations in the internal carotid arteries, which provide the major blood supply to the brain), in the aortic arch, and in the walls of nearly every large artery of the neck and thorax.
184
How do baroreceptors work to decrease blood pressure?
When stretched, baroreceptors send a rapid stream of impulses (action potentials) to the cardiovascular center, inhibiting the vasomotor and cardio-acceleratory centers and stimulating the cardioinhibitory center. Communicate with the ANS and tells it to turn off the sympathetic system. The result is a decrease in blood pressure (due to decreased heart rate, decreased contractility, and decreased cardiac output). Could also turn on parasympathetic system to slow down heart rate.
185
What are the two most important locations for baroreceptors?
aortic arch and carotid sinus
186
True or false: baroreceptors are primarily focused on regulating sustained, long term pressure changes.
False; Rapidly responding baroreceptors protect the circulation against short-term (acute) changes in blood pressure.
187
Describe the baroreceptor reflex changes that occur to maintain blood pressure when you rise from a lying-down to a standing position.
When you first stand up, mean arterial pressure (MAP) temporarily decreases and this is sensed by aortic and carotid baroreceptors. Medullary cardiac and vasomotor center reflexes increase sympathetic and decrease parasympathetic outflow to the heart. Heart rate and contractility increase, increasing cardiac output and therefore MAP. Further, sympathetic constriction of arterioles increases total peripheral resistance, also increasing MAP. In addition, increased constriction of veins increases venous return, which increases end diastolic volume, increasing stroke volume, and therefore cardiac output and MAP.
188
The kidneys play an important role in maintaining MAP by influencing which variable?
The kidneys help maintain MAP by influencing blood volume.
189
True or false. I am suffering from high blood pressure therefore I would produce the hormone aldosterone.
False, Aldosterone would serve to increase blood volume and therefore increase blood pressure.
190
What is the effect of dehydration on blood viscosity?
It increases blood viscosity, increases resistance, therefore increases blood pressure.
191
Give 2 physiological mechanisms to alter resistance. For each one say if it increases or decreases blood pressure.
- Alter blood vessel diameter. If you constrict the blood vessel, it will increase blood pressure. If you dilate the blood vessel, it will decrease blood pressure.
- Alter the viscosity of blood. If you increase viscosity (rbcs increase), viscosity will increase, resistance will increase and therefore blood pressure will increase. If you decrease viscosity (anemia), resistance will decrease and blood pressure will decrease.
192
You are suffering from low blood pressure. List 2 ways you will correct this using stroke volume.
- Increase strength of contraction - this will push more blood out of the ventricle and increase stroke volume. To increase strength of contraction you could activate the sympathetic system.
- Increase venous return and your end diastolic volume (EDV) - this will return more blood to the heart and therefore increase stroke volume. One way to do this is by increasing skeletal muscle activity.
193
List (don’t go into detail just make a list!) all the ways to increase EDV.
Increase use of skeletal muscle
Increase number of inspirations
Increase blood volume
194
I want to decrease my cardiac output. Explain in detail 2 physiological mechanisms which will do this.
Cardiac output = heart rate x stroke volume.
So, to decrease cardiac output, you can decrease the heart rate or decrease stroke volume (or both the same time). To decrease heart rate, you can activate the parasympathetic system. This will have ACh bind to muscarinic receptors in the cardiac muscle and result in a decrease heart rate. To decrease stroke volume, you can reduce the use of skeletal muscles (don’t move) or lower your rate of inspiration. Or you can decrease the force of contraction in the heart by turning off the sympathetic system.
195
True or false. In cardiac muscle, the action potentials differ from region to region within the heart, and they have different shapes and look a bit different.
True
196
Define venous return.
Amount of blood returning to the heart @ any one moment in time.
197
True or false. Baroreceptors have voltage-gated receptors that result in actions potentials when stretched.
False. Baroreceptors have receptors that respond to pressure. They stretch and this allows sodium to enter, which will lead to an action potential.
