Cardiovascular Physiology I: Excitation, Conduction, and Cardiac Cycle (Exam III) Flashcards
1
Q
The three principal components of the circulatory system are:
A
- the heart
- the blood vessels
- the blood
2
Q
The pump:
The pipes:
The fluid to be moved:
A
Heart
Blood vessels
Blood
3
Q
Cardiovascular function is regulated by ___ & _____ and strongly impacted by _____.
A
endocrine factors & autonomic nerves
renal function
4
Q
Number one cause of death worldwide:
A
cardiovascular disease
5
Q
____ & _____ are the most common cardiovascular diseases
A
atherosclerosis & HTN
6
Q
Cardiovascular disease affects many organs including:
A
brain, eyes, and kidneys
7
Q
Multiple risk factors of cardiovascular disease including:
A
smoking, obesity, DM, genetics
8
Q
A build up of plaque in the wall of a vessel causing the narrowing of the lumen
A
atherosclerosis
9
Q
The heart beats to generate ____ to push blood through the vessels
A
pressure
10
Q
The heart beats to ultimately allow blood to reach the ____.
A
capillary system
11
Q
Exchange at the capillary system occurs between:
A
plasma and interstitial fluid
12
Q
Supplies O2 and nutrients to the tissues and removes waste
A
systemic circulation
13
Q
Adds O2 and removes CO2:
A
pulmonary circulation
14
Q
Blood always enters the heart through the:
A
atria
15
Q
Blood always exits the heart through the:
A
ventricles
16
Q
Blood vessels that return blood to the heart:
A
veins
17
Q
Blood vessels that carry blood away from the heart
A
arteries
18
Q
Blood vessels that are attached to the atria, returning blood to the heart:
A
veins
19
Q
Blood vessels that are attached to the ventricles carrying blood away from the heart:
A
arteries
20
Q
What is the pump for systemic circulation:
A
Left ventricle
21
Q
What is the end goal for systemic circulation:
A
- supply O2 and nutrients to tissues
- removes waste
22
Q
Describe the path of systemic circulation:
A
The left ventricle pumps the blood out into systemic vessels and then into systemic capillaries and then into systemic veins. The systemic veins then bring blood back to the right atrium (end of systemic circulation)
23
Q
What is the pump in pulmonary circulation?
A
Right ventricle
24
Q
Describe the pathway of pulmonary circulation:
A
The right ventrical pumps blood into vessels that will carry it into the pulmonary capillaries, from here, the pulmonary vein will bring it back to the left atrium (this ends pulmonary circulation)
25
What is the end goal for pulmonary circulation?
Add O2 and remove CO2
26
Function is to keep blood flowing in one direction:
heart valves
27
Heart valves open and close due to:
changes in pressure
28
When we see vessels colored in red, what type of vessels are these and describe the blood within them:
Systemic arteries and blood is high in O2 and low in CO2
29
When we see vessels color coated blue, what type of vessels are these and describe the blood within them:
systemic veins and blood is high in CO2 and low in O2
30
What is the one artery that is carrying blood that is low in O2 and high in CO2?
pulmonary artery
31
What is the one vein that is carrying blood high in O2 and low in CO2?
pulmonary vein
32
The blood flow out of the left ventricle into systemic circulation is ____ compared to the blood that is pumped out into the right ventricle into pulmonary circulation:
EQUAL
33
Unequal blood flow between pulmonary and systemic would result in:
blood pooling
34
oxygen is loaded and CO2 is unloaded in the:
pulmonary capillaries
35
oxygen is unloaded and CO2 is loaded in the:
systemic cappilaries
36
Veins attached to the left atrium:
pulmonary vein
37
Large systemic artery attached to the left ventricle:
aorta
38
Large vein attached to the right ventricle
Pulmonary trunk
39
The pulmonary trunk will branch into:
right and left pulmonary arteries
40
Attached to the right atrium (returns blood to the right atrium)
Vena Cava
41
Valves are not _____ but are considered ____.
muscles; passive structures
42
Passive structures that open and close based on pressure gradients and function to keep blood flowing in one direction:
Heart valves
43
Valves found between the atria and respective ventricles:
atrioventricular valves (AV)
44
What are the two AV valves?
1. tricuspid valve
2. mitral vavle (biscuspid)
45
Where is the the tricuspid valve located?
between right atrium and right ventricle
46
Where is the mitral (biscuspid) valve located?
between left atrium and left ventricle
47
Valve located between the right atrium and right ventricle:
triscuspid
48
Valve located between the left atrium and left ventricle:
bicuspid (mitral)
49
If P(A)> P(V)=
open
50
If P(A)
closed
51
Valves located between the ventricles and there respective arteries:
semilunar valves
52
Valve located between right ventricle and pulmonary trunk:
pulmonary valve
53
Valve located between the left ventricle and the aorta
aortic valve
54
Where is the pulmonary valve located?
between the right ventricle and pulmonary trunk
55
Where is the aortic valve located?
between the left ventricle and the aorta
56
If P(V)> P(art) =
open
57
If P(V) < P(art)=
closed
58
When semilunar valves are open, the blood will be:
ejected out into the arteries
59
Prevents the back flow of blood into the ventricles when ventricular pressure falls:
Closing of the semilunar valves
60
Two loops in the cardiovascular system:
systemic loop & pulmonary loop
61
loop that carries oxygen rich blood to the systemic capillaries and oxygen poor blood back to the heart:
systemic loop
62
The systemic loops carriers oxygen rich blood to the _____ and oxygen poor blood ____.
systemic capillaries; back to the heart
63
The systemic loop carries _____ blood to the systemic capillaries and ____ blood back to the heart.
oxygen-rich; oxygen poor
64
Loop that carries oxygen poor blood to the lungs and oxygen rich blood back to the heart:
pulmonary loop
65
The pulmonary loop carries oxygen poor blood to the _____ and oxygen rich blood ____.
lungs; back to the heart
66
The pulmonary loop carries _____ blood to the lungs and ____ blood back to the heart
oxygen-poor; oxygen-rich
67
What occurs between the plasma and interstitial fluid at the capillaries?
exchange
68
Exchange occurs between _____ & ______ at the ____
plasma & interstitial fluid; capillaries
69
How is blood supply to tissue arranged?
Parallel
70
The cardiovascular system is considered a _____ system
closed
71
What is considered "bad" due to the cardiovascular system being a closed system?
leaks
72
A bleeding paper cut would be considered a _____ in the cardiovascular system.
leak
73
What repairs leaks in the cardiovascular system?
hemostasis
74
Vessels and capillary beds have a _____ arrangement
parallel
75
Why is it significant that all capillaries in systemic circulation are arranged in parallel?
Allows the body to selectively change blood flow to a certain tissue without affecting the blood flow to another area
76
There is around _____ of blood moving through the body every minute at rest:
~5 liters
77
Each tissue gets a different amount of blood because you can regulate how much blood flow goes into each tissue and that is due to the:
parallel arrangment
78
During strenuous exercise, where might the body increase blood flow to?
Brain, heart, skeletal muscles, and skin
79
During strenuous exercise, where might the body decrease blood flow to?
kidneys, abdominal organs, etc.
80
List the types of arteries:
1. elastic arteries
2. muscular arteries
3. arterioles
81
The largest arteries that are attached to the heart:
elastic arteries
82
Muscular arteries may also be called:
distribution arteries
83
Type of artery that branches off the aorta and function to distribute blood to and around different organs of the body:
muscular artery (distribution artery)
84
Where arteries come to an end (represent the end of arteries)
arterioles
85
Smallest arteries, connected to the capillaries
arterioles
86
Blood flows out of the arteriole system into the ___ through the ____
capillaries; arterioles
87
Function to carry blood to tissue capillaries from the heart:
arteries
88
What regulates blood pressure?
arterioles
89
What are the three types of veins?
1. large veins
2. medium-sized veins
3. venules
90
large veins are attached to:
the heart
91
What are some examples of large veins?
Vena Cava; Pulmonary vein
92
Medium veins are considered ____ veins
collection
93
Collect blood from different tissues that the muscular arteries delivered it to:
medium-sized veins (collection veins)
94
Smallest of veins, that captures the blood that flows out of the capillaries:
venules
95
Represent the beginning of the venous system:
venules
96
Venules collect into _____
medium-sized veins
97
Carry blood to the heart from tissues capillaries
veins
98
The process of carrying blood to the heart from tissue capillaries:
venous return
99
Veins serve as:
reservoir of blood
100
Veins have a very high compliance and can hold a large volume of blood with very little change in pressure and this can be referred to as:
peripheral venous pool (PVP)
101
Describe what peripheral venous pool means:
The ability of veins to act as a reservoir of blood
102
At rest, how much of our blood volume is contained within the veins:
~60%
103
The aorta is an example of an:
elastic artery
104
The aorta is attached to the:
heart
105
Describe the blood flow through the aorta:
blood is ejected out at a forceful pressure
106
Muscular arteries branch off of the:
aorta
107
Example of muscular arteries:
renal artery and celiac artery
108
Muscular arteries enter into the ____ and get smaller and smaller until they become ____.
organs and arterioles
109
______ will end with capillaries and this is where exchange will occur
arterioles
110
Exchange occurs in the capillaries, and that blood will get picked up by:
venules
111
For every artery we have a ____ component to it
venous
112
The force exerted by a fluid in a tube
pressure (hydrostatic pressure)
113
Pressure is measured in:
mmHg
114
In the cardiovascular system we are measuring what pressure:
pressure of blood in blood vessels
115
The volume of fluid moved in a given amount of time:
flow
116
Flow is measured in:
ml/min
117
How difficult it is for blood to flow between two points at any given pressure difference:
resistance
118
Resistance is a measure of:
friction that impedes flow
119
Ohm's law =
F= (Change in Pressure) / Resistance
120
Flow is directly related to ____; flow is inversely related to ____.
pressure gradient; resistance
121
What is the unit for resistance?
Poiseuille
122
If the change in pressure is constant and resistance increases, flow:
decreases
123
The driving force to move blood through the cardiovascular system
pressure gradient generated by the heart
124
From a mechanistic standpoint, which would be better to alter to change blood flow to specific tissues?
1. Increase in pressure
2. Decrease in resistance
Reduce resistance to flow because the driving pressure is your BP and we don't want to alter that much
125
Flow will be regulated by_____, and NOT _____.
regulating resistance; NOT changing pressure
126
As blood flows through systemic circulation (aorta --> arteries --> arterioles --> capillares --> venules --> veins --> vena cava) What happens to the pressure and why?
Pressure decreases due to friction (resistance) as you move away from the heart
127
Where is pressure CV system the highest?
Immediately outside the left ventricle
128
Where is the biggest pressure drop in systemic circulation?
arterioles
129
The biggest pressure drop occurs in the arterioles due to:
most resistance/friction there
130
What are the three factors that contribute to cardiovascular resistance?
1. blood viscosity (n)
2. total blood vessel length (l)
3. blood vessel radius (r)
131
Resistance is directly related to _____; resistance is indirectly related to _____.
blood viscosity (n) and total blood vessel length (l)
blood vessel radius (r)
132
How thick the blood is =
viscosity
133
Viscosity is determined by:
hematocrit
134
Percentage of red blood cells per unit of whole blood:
Hematocrit
135
The more red blood cells present per unit of whole blood =
higher viscosity
136
How much tubing is needed:
total blood vessel length
137
The longer the blood vessel, the _____ the resistance
greater
138
What determines blood vessel length?
genetics
139
Vasodilated blood vessels increase ____ and decrease _____.
radius; resistance
140
Vasoconstricted vessels decrease ___ and increase ____
radius; resistance
141
What is the main contributor to minute-to-minute control of resistance in the vascular system?
blood vessel radius
142
Small changes in blood vessel radius lead to:
big changes in resistance
143
If we want to increase blood flow to an area we can _____ the blood vessel; but if we want to reduce blood flow to an area we can _____.
dilate; constrict
144
What is poiseuille equation?
Resistance= 8nl / pi(r)^4
n= viscosity
l= length
r= radius
145
By combining poiseuille law and ohm law we get:
Q= P(pi)r^4 / 8nl
Hagen-poiseuille equation
146
When regarding pressure and flow in vessels, its not the ____ of pressure that is important, it is the ____ of the pressure that is important.
absolute values of pressure; differences in pressure
147
Diameter of a vessel is a major determinant of:
flow
148
A two-fold increase in radius will lead to a:
16 fold increase in blood flow
149
Describe the effects the following have on flow:
1. Increased radius
2. Decreased radius
3. Increased tube length
4. Decreased tube length
1. increased flow
2. decreased flow
3. decreased flow
4. increased flow
150
What is the equation for velocity regarding blood flow through vessels?
V = Q/A
V= velocity
Q= blood flow
A= total cross sectional area
151
How something happens:
mechanistic explanation
152
Why something happens:
teleological explanation
153
Velocity of blood flow is slowest through the capillaries, what is the mechanistic explanation for this?
greatest total cross-sectional area leads to the lowest velocity
(1 aorta = low cross sectional area compared to many capillaries= highest cross sectional area)
(V=Q/A)
154
Velocity of blood flow is slowest through the capillaries, what is the teleological explanation for this?
We want velocity to be slow at the capillaries to allow time for maximum exchange to occur
155
Describe the following at the aorta:
1. total cross-sectional area
2. velocity of blood
3. blood pressure
1. low cross-sectional area
2. high velocity of blood flow
3. high blood pressure
156
Describe the following at the capillaries:
1. total cross-sectional area
2. velocity of blood
3. blood pressure
1. large cross-sectional area
2. low velocity of blood flow
3. low blood pressure but higher than in the venules, veins and vena cava
157
Connective tissue cords that are attached to the AV valves on one end and papillary muscles located inside the ventricles on the other end:
chordae tendinae
158
What does the chordae tendinae connect to?
AV valves and papillary muscles
159
The walls of the atria are _____ compared to the walls of the ventricles.
thinner
160
What is the mechanistic explanation the walls of the atria being thinner than the walls of the ventricles:
The walls of the atria are thinner because the atria only have to contract to push blood into the ventricles (not a ton of work)
161
Compare the walls of the right ventricle to the left ventricle:
Wall of left ventricle is much thicker
162
What is the mechanistic explanation of the left ventricle wall being thicker than the right ventricle wall?
Left ventricle is responsible for systemic circulation, it has to forcefully contract to get blood all the way to the toes (a lot of work)
163
Separates the right ventricle from the left ventricle:
Interventricular septum
164
List the AV valves and where they are located:
1. tricuspid valve (RA/RV)
2. Bicuspid (mitral) valve (LA/LV)
165
The AV valves are supported by _______ when closed
Chordae tendinae and papillary muscles
166
When the AV valves are open, the semilunar valves are:
closed
167
When are all valves open at the same time?
NEVER
168
When AV valves are open, blood is flowing into the:
ventricles
169
Describe the chordae tendinae when the AV valves are open?
Lots of slack (not drawn tight)
170
When the AV valves are closed, the semi lunar valves are:
open
171
Describe the chordae tendinae when the AV valves are closed:
chordae tendinae stretched tight and supported by the papillary muscle
172
The function of the chordae tendinae is to:
prevent backflow
173
What would happen if the chordae tendinae were not functioning?
valve prolapse
174
Caused by weakened/stretch chordae tendinae and can be due to HTN:
Valve prolapse
175
Valve dysfunction creates:
heart murmurs
176
Valves open and close due to:
pressure gradients
177
Valves function to:
keep blood flowing in one direction
178
Which valve is considered the tricuspid valve?
Right AV valve
179
Which valve is considered bicuspid valve?
Left AV valve
180
Cardiac myocytes can also be called:
cardiocytes, cardiac muscle cells
181
There are two types of cardiac myocytes in cardiac muscle and these include:
1. conductive muscle fibers (Autorhythmic cells (AR cells), Pacemaker cells)
2. Contractile muscle fibers
182
Conductive muscle fibers may also be called:
autorhythmic cells (AR Cells)
pacemaker cells
183
Makes up 1% of cardiac myocytes:
conductive muscle fibers
184
Spontaneously generate AP that leads to heart beat:
conductive muscle fibers
185
______ stimulus an excitation (AP) which stimulates ______.
conductive muscle fibers; contractile cells
186
Type of cardiac myocyte that contract very weakly:
conductive muscle fibers
187
Conductive muscle fibers are located:
in conduction system of heart
188
99% of myocytes=
contractile muscle fibers
189
contract and generate heart beat:
contractile muscle fibers
190
What are the 2 types of contractile muscle fibers?
1. atrial myocytes
2. ventricular myocytes
191
cardiac muscle cell that contracts in response to the electrical signal that is generated by conductive muscle cells
Contractile muscle fibers
192
Contractile muscle cells located in the atria:
atrial myocytes
193
contractile muscle cells located in the ventricles:
ventricular myocytes
194
What stimulates SKELETAL muscle to contract?
action potentials and somatic motor neurons
195
What are the steps for (simplified) to stimulating a SKELETAL muscle to contract?
1. AP in somatic motor
2. release of Ach
3. Ach binds to nicotinic receptors on motor end plate
4. Excitation leading to calcium entry (for contraction)
196
Compare heart contraction to skeletal muscle contraction:
No outside electrical stimulus is needed for the heart to beat
197
Where does the electrical signal that leads to heart contraction come from?
from WITHIN the heart
198
What enables the heart to beat outside of the body?
internal stimulation from conductive muscle fibers
199
The appearance of cardiocytes can be described as:
striated
200
The functional unit of a cardiocyte:
sarcomere
201
The _____ and _____ of cardiac muscle is similar to skeletal muscle
anatomy and function
202
Cardiac muscle can be described as a _____.
syncytium
203
group of cells that function as one:
syncytium
204
What feature of cardiocytes allows them to function as a syncytium?
intercalated discs
205
specialized connections between one cardiac muscle cell and another
intercalated disc
206
Intercalated discs are composted of:
1. interlocking plasma membrane
2. gap junctions
3. desmosomes
207
Describe the interlocking plasma membrane of intercalated discs in cardiac muscle:
Little hooks locking the plasma membrane together
208
Describe the function of the gap junction found in intercalated discs in cardiac muscle:
allows for rapid movement of ions from one cell to the next
209
Describe the function of desmosomes found in intercalated discs in cardiac muscle:
Structural support cell connections
210
Why is it so important that desmosomes are found in the intercalated discs in cardiac muscle?
Allows the cells to stay together under the extreme pressure of the heart
211
In what ways are cardiac muscle cells linked?
1. mechanically
2. chemically
3. electrically
212
What are the two syncytiums of the heart?
1. atrial
2. ventricular
213
The atrial syncytium and the ventricular syncytium function:
separate of eachother
214
If the atrial syncytium is contracted, the ventricular syncytium is ____.
relaxed
215
The arteries supplying the myocardium are the:
coronary ateries
216
The blood flowing through the coronary arteries:
coronary blood flow
217
Coronary arteries exit from behind the ____.
aortic valve cusps
218
Coronary arteries exit form the behind the aortic valve cusps and lead to a branching network for:
small arteries, arterioles, capillaries, venues and veins
219
Describe the drainage of most of the cardiac veins:
most of the cardiac veins drain into a single large vein- the coronary sinus
220
After the cardiac veins drain into the single coronary sinus, this empties into the:
right atrium
221
Coronary circulation is a part of:
systemic circulation
222
because coronary circulation is part of systemic circulation it functions to:
provide O2 and nutrients to tissues of the body (including the heart)
223
Systemic blood flow to the heart and prices fresh O2 and nutrients to the cells
coronary cirulation
224
What does coronary circulation bypass?
vena cava
225
The coronary sinus dumps directly into the:
Why is this unique?
right atrium; because it bypasses the vena cava
226
The very 1st branch off the aorta is the:
coronary artery
227
The coronary artery branches into:
right and left coronary arteries (which travel around the heart)
228
Lack of blood supply to the left ventricle:
widow maker
229
What is the artery involved in widow maker?
Left anterior descending artery (coronary artery??)
230
What is the only thing that does not use the vena cava to dump blood back into the heart?
coronary sinus
231
Contraction=
systole
232
relaxation=
diastole
233
atrial contraction=
atrial relaxation=
ventricular contraction=
ventricular relaxation=
atrial systole
atrial diastole
ventricular systole
ventricular diastole
234
What is the term for the events occurring in a single heart beat
cardiac cycle
235
The events of the cardiac cycle include:
1. atrial systole
2. ventricular systole/atrial diastole
3. ventricular diastole
236
What must occur before systole can happen? What must occur before diastole can happen?
heart muscle must depolarize before systole can happen and repolarize before diastole can happen
237
What is the order of depolarization in the heart/conduction system?
1. SA Node
2. Internodal pathways
3. AV node
4. Bundle of His
5. Down bundle branches
6. Up purkinje fibers
238
The SA node will generate AP which travel via gap junctions along _______ to the ______
internodal pathways; AV node
239
The action potential is held up for 0.1s in the _____. This is known as the _____.
AV node; AV delay
240
What is the teleological explanation for the AV delay?
The atria needs to contract before the ventricles fill with blood
241
What is the mechanistic explanation for the AV delay?
The conduction velocity through the AV node is slower than elsewhere along the conduction system
242
The AP travels from the AV node ______ the bundle of His, ____ bundle branches, ____ purkinje fibers
Down, down, up
243
The purkinje fiberse also supply the ____
papillary muscles
244
Contracts during ventricular contraction to tighten the chordae tendinae and prevent AV valves from prolapsing into the atria
Papillary muscles
245
When do the papillary muscles contract?
during ventricular contraction
246
The pacemaker cells with the _____ drive the heart
fastest rate of discharge
247
In general, pacemaker cells have high _____.
What is an exception to this?
action potential conduction velocities
exception: AV node (due to AV delay)
248
The reason that the action potential is held up for a fraction of a second at the AV node is because it has ____ which causes the AP to take longer to move through this area.
Very slow conduction velocity
249
The speed at which the action potential moves
conduction velocity
250
the number of APs the pacemaker cells can generate in a given amount of time
rate of discharge
251
Why does the SA node drive the heart?
because it contains the pacemaker cells with the fastest rate of discharge
252
Describe an ectopic focus
abnormal pacemaker cells (hijackers)
253
If contractile cells convert into AR cells like after a long infection these would be considered:
ectopic focus
254
Describe the events that occur when the action potential takes the internodal pathways?
1. depolarization of atria
2. AV delay
3. atrial contractions
255
Describe the events that occur when the AP is sent down the bundle branches and up purkinje fibers:
1. depolarization of ventricle
2. contraction of ventricles
256
Atrial repolarization occurs at the exact same time as _____.
Describe the wave of atrial repolarization on an ECG.
Ventricular depolarization
Because it occurs at the same time as ventricular depolarization (it is dominated since the ventricles are bigger) and therefore is absent on an ECG
257
Name the wave that is characterized by the following actions:
1. atrial depolarization
2. ventricular depolarization/atrial repolarization
3. ventricular repolarization
1. P wave
2. QRS complex
3. T wave
258
The p wave itself does not represent atrial ______ but it represents atrial _____.
contraction; depolarization
259
Does the QRS complex represent atrial repolarization? why?
No- It represents ventricular depolarization although atrial repolarization does occur at this time (just not represented on ECG)
260
AV delay occurs during the PR interval, if AV delay is longer than normal = ________. If AV delay is shorter than normal = ________.
longer PR interval; shorter PR interval
261
When would the Q- wave show up on an ECG?
Not normally, only on someone with previous cardiac event
262
AR cells do not have a:
steady resting membrane potential
263
Describe the resting membrane potential of AR cells:
unsteady
264
depolarization to threshold in AR cells:
pacemaker potential
265
What are the two channels of pacemaker potential?
F-type channels
T-type channels
266
F-type channel=
Voltage gated sodium channel (funny channel)
267
T-type channel=
Transient voltage gated calcium channel
268
What are the two channels of AP?
L channel
K+ channel
269
L Channel=
long-lasting voltage gated calcium channel
270
Once the membrane potential hits the resting potential that will be stimulus for:
opening of F-type channel
271
What happens when the F-type channel opens?
Sodium influx into the cell leading to depolarization to 3/4 of threshold
272
At resting potential, sodium permeability is _____. But as soon as the F-type channel opens, ______.
low; Na+ permeability increases
273
At 3/4 the way up to theshold what occurs?
Transient voltage gated calcium channels open
274
Why doe we call them "transient" voltage gated calcium channels?
because they only open briefly
275
The calcium flowing in due to the transient voltage gated calcium channels allows for:
depolarization to threshold (the final 1/4)
276
What work together to get the cell to threshold?
F-type channel + transient voltage gated calcium channel
277
Once we reach threshold, what occurs?
L-Type calcium channels open, calcium flows in = spike of depolarization
278
Describe the opening of the L-type calcium channel:
Long lasting opening at threshold
279
At the peak of deploarization the L type calcium channel _____, and the permeability of calcium ____.
closes; goes down
280
When the L-type calcium channels close, _____ opens.
voltage gated potassium channels
281
The increased permeability to potassium (opening of K+ channels) leads to:
repolarization to rest
282
As soon as repolarization to rest occurs what happens?
process starts over again (with F channels opening)
283
In skeletal muscle, the depolarizaiton of neurons is due to ______, while in cardiac muscle, the depolarization of AR cells is due to _____.
sodium; calcium
284
Describe what neurotransmitters are involved in sympathetic control of AR cells:
Epi and NE
285
Describe what neurotransmitters are involved in parasympathetic control of AR cells?
acetylcholine
286
What receptors do NE and epi bind to?
beta 1 adrenergic
287
What receptors do acetylcholine bind to?
muscarinic
288
Describe the effects of NE and E binding to beta-1 adrenergic receptors to control AR cells:
- Increase in probability of opening F-type channels and transient calcium channels
- Decrease in time to threshold
- Increase in HR
289
The aspects of sympathetic control on AR cells are considered:
positive chronotropic agens
290
Describe the effects of Ach binding to muscarinic receptors to control AR cells:
- decrease in probability of opening F-type channels
- Increase in probability of opening of K+ channels
- Hyperpolarization of membrane
- Increase in time to threshold
- Decrease in HR
291
The aspects of parasympathetic control on AR cells are considered:
negative chronotropic agents
292
Agents that function to increase HR:
Agents that function to decrease HR:
1. positive chronotropic agents
2. negative chronotropic agents
293
Facilitated diffusion rate of ion= (equation)
(Change in concentration)x (temperature) x (# of channels)
------------------------------------------------------------------------------------
Probability of opening of channels
294
________ we need to be able to change the HR based on the needs of the body
teleologically
295
SA node spontaneous rate =
Normal resting HR=
Meaning the heart is under ______ NS control
100bpm
80bpm
parasympathetic
296
Contractile Cell Depolarization Events:
Phase 4=
Caused by:
resting membrane potential- sodium channels reset gate and are ready for next AP
297
Contractile Cell Depolarization Events:
Phase 0=
Caused by:
spike of depolarization- due to sodium entry through fast voltage gated sodium channel- activation/inactivation gates are open here
298
Contractile Cell Depolarization Events:
Phase 1=
Caused by:
Partial repolarization- fast gated sodium channels close,
299
Contractile Cell Depolarization Events:
Phase 2=
Caused by:
plateau- transient potassium channels close and L-type calcium channels open
300
Contractile Cell Depolarization Events:
Phase 3:
Caused by:
Repolarization- L-type calcium channels close, slow K+ channels open
301
Unlike AR cells, contractile cells have:
resting membrane potential
302
Plateau phase is unique to:
contractile cells (does NOT) occur in NS or skeletal system
303
During this phase of contractile cell AP, the number of positive charges entering the cell is equal to the number of positive charges exiting the cell:
plateau phase
304
Atrial cell contraction corresponds to what wave on an ECG?
P-wave
305
Ventricular depolarization corresponds to what wave on an ECG?
QRS complex
306
Ventricular repolarization corresponds to what wave on an ECG?
T-wave
307
The ____ cells have the AP with the pacemaker potential, while the _____ cells have the AP with the plateau
AR cells; contractile cells
308
What are located in the membrane of T-tubules in contractile cells?
DHP L-type calcium channels
309
What stimulates the DHP L-type calcium channels to open?
Stimulated to open when AP reaches them
310
What are the two ways to reduce cytosolic calcium following contractile cell contraction?
1. calcium ATPase in SR membrane (primary active uniporter)
2. secondary antiporter in PM (sodium in, calcium out)
311
Excitation contraction coupling in cardiac muscle:
Excitation (depolarization of the plasma membrane) leads to:
Opening of plasma membrane L-type Calcium channels in T-tubules
312
Excitation contraction coupling in cardiac muscle:
Following the opening of plasma membrane L-type channels in t-tubules, what occurs?
flow of calcium into the cytosol from the ECF (10%)
313
Excitation contraction coupling in cardiac muscle:
After calcium flows into the cell from the cytosol, what occurs?
calcium binds to calcium ryanodine receptors on the outer membrane of the SR
314
Excitation contraction coupling in cardiac muscle:
After calcium binds to the ryanodine receptors of the SR, what occurs?
Flow of calcium out of the SR and into the cytosol (90%)
315
When calcium from outside the cell causes calcium from inside the SR to be released into the cytosol, this is known as:
calcium-induced-calcium release
316
Excitation contraction coupling in cardiac muscle:
Once the bulk of calcium (90%) flows into the cytosol from the SR with the addition of the other 10% of calcium from the ECF this ultimately causes:
Increase in cytosolic calcium concentration, cross-bridge cycling and contraction
317
In both skeletal muscle and cardiac muscle contraction, _____ is required.
calcium
318
In both skeletal and cardiac muscle contraction, ______ begins once calcium binds to troponin
cross-bridge cycling
319
In both skeletal and cardiac muscle contraction, a _____ pumps calcium back into the _____.
primary active uniporter; SR
320
A difference between cardiac and skeletal muscle contraction is that in addition to the primary active uniporter, cardiac muscle uses a _____ in the membrane to pump calcium into the _____.
secondary active antiporter; ECF
321
In skeletal muscle, all the calcium from contraction comes form the _____ while in cardiac muscle, some calcium comes from ______ and the rest comes from _____
SR; ECF and SR
322
In skeletal muscle, the AP is very quick and over before the contractile event even begins which allows for:
summation and tetanus to occur
323
What aspect of cardiac muscle contractile events causes the AP to be longer?
plateau phase
324
In cardiac muscle contraction, the contractile event occurs simultaneously with the:
Electrical activity in the cell
325
In cardiac muscle contraction, by the time the muscle has returned to its resting state, the ____ is already over
Because of this, _____ and ____ cannot occur
contractile event
summation and tetanus
326
What is the mechanistic explanation of cardiac muscles inability to go into summation and tetanus?
Because the duration of the absolute and relative refractory periods is so long that by the time you can actually generate another AP, the muscle has relaxed
327
What is the teleological explanation of cardiac muscles inability to go into summation and tetanus?
We do not want our heart to go into summation and tetanus, we want our heart to contract and relax in between beats so we can fill the heart with blood and pump it out to the body
328
Where does the electrical signal for skeletal muscle contraction come from? What stimulates contractile cells to contract?
somatic motor neurons; AP from the AR cells
329
In skeletal muscle, contraction response to a single AP is:
All or none
330
Graded potential is the opposite of:
all or none- it may happen differently every time
331
Because skeletal muscle contractile response to a single AP is all or none, the calcium released saturates _____ and contraction strength is _____.
troponin; maximal
332
In cardiac muscle, contractile response to a single AP is:
graded
333
In "resting" state, AP-induced sarcoplasmic release of calcium in cardiac cells does NOT:
saturate troponin sites
334
The strength of contraction in cardiac muscle is dependent on:
the concentration of calcium inside the cell
335
The amount of intracellular calcium is adjusted to:
change or increase the strength of contraction
336
Substances that alter the force of contraction of cardiocytes by changing the cytosolic calcium concentration are termed:
inotropic agents
337
Inotropic agents change the _____ of the heart
contractility
338
Positive inotropic agents _____ the force of contraction
Negative inotropic agents _____ the force of contraction
Increase; decrease
339
Inotropic agents work via:
voltage gated calcium channels
340
Under sympathetic influence, describe what happens to heart contraction?
More forceful contraction and shorter duration of contraction
341
When epinephrine and norepinephrine bind to _______ which are GPCRs, these activate ________.
Beta-1 adrenergic receptors; CAMP
342
When Epinephrine and NE bind to beta-1 adrenergic receptors causing activation of CAMP, this results in what two things:
1. phosphorylation of voltage-gated calcium channels
2. phosphorylation of phospholambin
343
When CAMP causes the phosphorylation of voltage-gated calcium channels, this causes the voltage gated calcium channels to ______ resulting in ______.
stay open longer resulting in increased calcium entry from ECF
344
Because phosphorylation of the voltage gated calcium channels allows them to stay open longer and bring more calcium into the cell from the ECF, This leads to what 3 things?
1. Increased calcium stores in SR
2. Increased calcium release from SR
3. More forceful contraction
345
CAMP phosphorylating phospholamban increased the activity of ______ in the SR
calcium ATPase
346
The increased activity of the calcium ATPase in the SR (caused by phosphorylation via camp on phospholamban) leads to :
1. increased calcium stores in the SR
2. faster calcium removal from cytosol
347
The chain events of phosphorylation of phospholamban that ultimately increase the calcium ATPase activity which increases calcium stores in the SR and causes calcium to be removed faster from cytosol more quickly leads to:
1. increased calcium release from SR leading to a more forceful contraction
2. Shortens Ca-troponin binding time leading to a shorter duration of contraction
348
Ultimately under sympathetic influence on contractile cells, you get:
1. more forceful contraction
2. quicker duration of contraction
349
Pressure Aria < Pressure Veins
Pressure Atria > Pressure Ventricles
Pressure Ventricles < Pressure Arteries
Between Beats
350
Describe the atria and ventricles between beats:
completely relaxed (in diastole)
351
Between beats, the the pressure of the atria is less than the pressure in the veins, therefore:
blood will flow into the atria
352
Between beats, the pressure of the atria is greater than the pressure in the ventricles, therefore:
AV valves are open so blood is flowing into the ventricles
353
Between beats, the pressure of the ventricles is less than the pressure in the arteries, therefore:
The semilunar valves are shut
354
Between beats, the blood returning to the right atrium is from the:
Between beats, the blood returning to the left atrium is from the:
systemic circulation
pulmonary circulation
355
Between beats is the period of _______, meaning:
Period of Passive Filling- 80% of blood for contraction is loaded into the ventricles at this time
356
Pressure of atria is elevated
Pressure atria> Pressure veins
Pressure atria> Pressure ventricles
Pressure ventricles < Pressure arteries
Atrial systole
357
During atrial systole:
1. The pressure of the atria is greater than the pressure of the veins, therefore:
2. The pressure of the atria is greater than the pressure of the ventricles, therefore:
3. The pressure of the ventricles is less than the pressure of the arteries, therefore:
1. potential backflow into the veins may occur
2. AV valves are open
3. Semilunar valves are shut
358
As the atria contracts, blood will travel into the:
ventricles
359
Atrial systole is a period of ______ meaning ______.
Period of active filling; 20% of blood for contraction is loaded into the ventricles at this time
360
Pressure of atria decreased
Pressure of ventricles increased
Pressure atria < Pressure veins
Pressure atria < pressure ventricles
Pressure ventricles < pressure arteries
Atrial diastole/early ventricular systole
361
In atrial diastole/early ventricular systole:
1. The pressure of the atria is decreased because:
2. The pressure of the ventricles is increased because:
3. The pressure of the A < Pressure of veins therefore:
4. The pressure of the atria < pressure of the ventricles therefore:
5. The pressure of the ventricles
1. the atria are relaxed
2. the ventricles contract
3. blood will start flowing back into the atria
4. AV valves will shut
5. Semi lunar valves are shut
362
We've filled the bag with blood and now closed all entrances and exits and then we start to squeeze causing a rapid rise in pressure in ventricles:
What stage of the cardiac cycle does this describe?
Atrial diastole/ early ventricular systole
363
During atrial diastole/early ventricular systole is the period of ____ meaning that:
period of isovolumetric contraction; pressure in ventricles rises rapidly
364
Pressure atria< pressure veins
Pressure atria < pressure ventricles
Pressure ventricles > pressure arteries
Late ventricular systole
365
In late late ventricular systole:
1. The pressure of the atria is less than the pressure of the veins, therefore:
2. The pressure of the atria is less than the pressure in the ventricles, therefore:
3. The pressure in the ventricles is greater than the pressure in the arteries, therefore:
1. blood will be flowing into the atria
2. The AV valves are shut
3. Semilunar valves are open and blood will be ejected into the arteries
366
During late ventricular systole is the ________ meaning ______.
Ejection phase; equal volume of blood ejected into both circulations
367
In the ejection phase where is the blood ejected into?
aorta on the left side and pulmonary trunk on the right side
368
Pressure of ventricles is decreased
Pressure atria < pressure veins
Pressure atria < pressure ventricles
Pressure ventricles < pressure arteries
early ventricular diastole
369
During early ventricular diastole:
1. Pressure of ventricles is decreased because:
2. Pressure of atria is less than the pressure of the veins, therefore:
3. Pressure of atria is less than the pressure of the ventricles, therefore:
4. Pressures of the ventricles is less than the pressure of the arteries, therefore:
1. because ventricles are relaxing
2. so blood will be flowing into atria
3. AV valves will be shut
4. Semilunar valves are shut
370
So we have emptied this bag of atleast half of its volume, closed both entrances and exits, and have allowed it to relax
This describes what stage of the cardiac cycle?
early ventricular diastole
371
During early ventricular diastole is the period of _____ meaning:
Period of isovolumetric relaxation meaning the pressure of the ventricles falls rapidly
372
Pressure atria< pressure veins
Pressure atria> pressure ventricles
Pressure ventricles < pressure arteries
Late ventricular diastole
373
During late ventricular diastole:
1. The pressure pressure of the atria is greater than the pressure of the ventricles, therefore:
2. The pressure in the ventricles is less than the pressure in the arteries, therefore:
1. AV valves are open- we start to fill the ventricles again
2. Semilunar valves are shut
374
During late ventricular diastole, the period of ______ begins.
Period of passing filling (again)
375
Volume of blood in the ventricle before it contracts (at the end of ventricular diastole)
end diastolic volume
376
EDV=
end diastolic volume
377
The average EDV=
135 ml
378
The volume of blood that is in the ventricle at the end of ventricular systole (the minimum amount of blood after contraction)
end systolic volume (ESV)
379
ESV=
end systolic volume
380
What is the average ESV?
65ml
381
Volume of blood ejected per beat:
stroke volume
382
Stroke volume (SV) =
(equation)
EDV- ESV
383
An average stroke volume is around:
70ml/beat
384
Fraction of EDV ejected per beat:
ejection fraction
385
Equation for ejection fraction:
SV/ EDV
386
The average ejection fraction is _____ at rest
52%
387
Heart sounds are due to:
valve closures
388
What causes the 1st heart sound?
Closure of AV valves
389
What causes the 2nd heart sound?
closure of semilunar valves
390
Abnormal heart sounds due to valve dysfunction:
heart murmurs
391
Heart murmur caused by failure of valves to open completely:
stenosis
Lub-shhh-dub
392
Heart murmur caused by failure of valves to close properly:
Insufficiency or prolapse
Lub-dub-shhh
393
Compare pressure changes in pulmonary circulation to the pressure changes in systemic circulation:
Pressure changes in pulmonary circulation are much smaller
394
The amount of blood pumped out of each ventricle in one minute:
cardiac output
395
Equation for cardiac output:
CO= HR x SV
396
Normal resting CO= 70bpm x 70 ml/beat=
5L per minute
397
During intense exercise, CO can:
elevate (30-35 L/min)
398
CO is regulated to match:
demands of tissues
399
What factors can increase CO?
- physical activity
- metabolic status
- drugs
400
What factors can decrease CO?
- blood loss
- heart disease
401
How can we control CO?
by changing HR and SV
402
Factors that increase HR
positive chronotropic agents
403
Factors that decrease HR
negative chronotropic agents
404
HR is mainly controlled by:
input from the nervous system
405
_____ increases the heart rate (AR and contractile cells)
____ decreases heart rate (AR cells only)
SNS; PNS
406
If we want to affect the heart rate we want to change the function of ____ cells, NOT ____ cells
AR cells; contractile cells
407
In order to increase heart rate we need to (2):
1. Increase speed at which APs are generated by SA node
2. Increase speed at which those APs travel through the conduction system
408
Factor that increases the speed at which the action potential moves through the myocardium:
What NTs might do this?
positive dromotropic agent
Epinephrine & NE
409
Factor that reduces the speed at which the AP moves through the myocardium:
What NTs might do this?
negative dromotropic agent
Acetylcholine
410
Equation for stroke volume (SV)
SV= EDV-ESV
411
SV is altered by:
1. change in preload (EDV)
2. change in afterload (BP)
3. change in contractility (force of contraction)
412
At rest, cardiac muscle sits at a length that is:
less than optimum
413
___EDV: ___ stretch of myocardium: moves cardiocyte length toward ____: ____SV
Increase; increased; optimum; increased
414
Starling Law of the heart states:
Increased EDV leads to Increased SV
415
Anything that increased EDV increases what two things?
force of contraction and stroke volume
416
Stroke volume is an index of:
force of contraction
417
EDV is an index of:
resting fiber length
418
EDV is ____ to venous return (VR)
directly related to
419
Rate at which blood is returned to the heart from veins
VR
420
High compliance, flaccid vessels that can hold up to 60% of the total blood volume:
veins
421
Can expand to hold more blood with out a change in pressure:
veins
422
The change in pressure to return blood to the heart from the capillaries is:
very small
423
_____ facilitates blood movement back to the heart (venous return)
one-way valves
424
Factors that increase VR that are dependent on one-way valves in veins:
1. increase in skeletal muscle pump
2. increase in thoracic pump
3. increase in venoconstriction via sympathetic NS
425
The increase in venoconstriction via the sympathetic nervous system increasing venous return is due to what receptors?
alpha-1 adrenergic receptors
426
What is one factors that increases VR that is NOT dependent on one way valves in veins:
Extremely high HR (tachycardia) because this causes a drop in EDV which leads to a drop in CO leading to a lower stroke volume
427
increasing thoracic pressure against a closed glottis, used during defecation reflex:
valsalva maneuver
428
Valsalvas maneuver functions to ____ venous return because it crease a large increase in thoracic pressure, which ____ VR, ____ EDV, ____SV, ___ CO
decrease all of them
429
How is HR related to SV?
indirectly related
430
How is CO related to HR (at a NORMAL HR)
directly related
431
_____ has a greater affect on CO than ____ under normal conditions
HR; SV
432
When you increase HR, you increase CO, however past _____ increasing HR will lead to a decrease in CO and this is because:
200bpm; you do not have enough time to fill the ventricles with blood before they beat, reducing EDV and SV and CO
433
The pressure that the ventricles must overcome to force open the aortic and pulmonary valves
afterload
434
Anything that increases systemic or pulmonary arterial pressure can _____ the afterload
increase (hypertension)
435
Increase in afterload causes a ____ In SV
decrease
436
_____ is not a major factor in healthy subjects
afterload
437
Peak pressure in ventricle:
systolic BP
438
Pressure at which the semilunar valves open and minimum pressure in aorta=
diastolic BP
439
At 130/90 what pressure is needed to open the semilunar valves?
90
440
If the heart has to work harder to open the valves (increased BP for example), the heart will _____ and this will lead to ____.
grow; left ventricular hypertrophy
441
Anything that increases the afterload on the heart will lead to a ____ in SV
reduction
442
The ability of the heart to contract at any given resting fiber length
Contractility
443
The ventricles are never completely empty of blood (ejection fraction), so a more forceful contraction will:
expel more blood with each pump
444
Contractility is varied by controlling the amount of ____ that enters the contractile cell via _____ gated channels
Ca++; L type voltage gated Ca++ channels
445
Because the amount of calcium that enters the cell via the L-type voltage gated ca++ channels determines the contractility of the muscle, this is considered a _____ contration
graded
446
What effects does a positive inotropic agent have on contractility and ejection fraction
Increase in contractility and increase in ejection fraction
447
Give examples of positive inotropic agents:
Sympathetic stimulation and epinephrine
448
What effects does a negative inotropic agent have on contractility and ejection fraction?
Decrease in contractility and decrease in ejection fraction
449
Give examples of negative inotropic agents:
beta 1 blockers and Ca++ Channel blockers
450
Adrenergic effects on cardiac muscle contractility: (2)
1. increase force
2. increase speed
451
Adrenergic effects on cardiac muscle contractility:
The SNS releases Epi and NE which bind to:
Beta1 adrenergic receptors
452
Adrenergic effects on cardiac muscle contractility:
When Epi and NE bind to beta1 adrenergric receptors in the contractile cell membrane, this activates:
The inactive CAMP dependent protein kinase
453
Adrenergic effects on cardiac muscle contractility:
When the CAMP-dependent protein kinase becomes activated, what effects are seen in the contractile cell? (3)
1. VG L-type calcium channel gets phosphorylated
2. Myosin heads get phosphorylated
3. Calcium ATPase activity in SR membrane is increased (indirect through phospholambin)
454
Adrenergic effects on cardiac muscle contractility:
Further explain the effects of the VG L-type calcium channel after it is phosphorylated:
This increases the FDR (the rate that calcium ions come into the cell- bc the probability that the channel is open)
The increased FDR results in more calcium release form SR which leads to a greater calcium spike, more troponin bound to calcium and therefore a MORE FORCEFUL CONTRACTION
455
Adrenergic effects on cardiac muscle contractility:
Further explain what happens when the myosin heads get phosphorylated by CAMP-dependent protein kinase?
When myosin heads get phosphorylated, this will cause the heads to cycle faster which will GENERATE TENSION MORE QUICKLY
456
Adrenergic effects on cardiac muscle contractility:
What aspect of the SNS affects on contractile cells is considered "contractility effect"
Voltage gated calcium channels getting phosphorylated causing a more forceful contraction
457
Adrenergic effects on cardiac muscle contractility:
Further explain what happens to the activity of the calcium ATPase
This occurs indirectly through phosolambin- When the calcium ATPase gets phosphorylated, its activity increases therefore the rate of calcium removal from the cytosol is increased so the cell can relax faster
458
Under the effects of SNS on contractile cells:
1. The overall amount of tension will go up. Why?
2. Speed of tension development will be quicker. Why?
3. Muscle will relax more quickly. Why?
1. Due to increased amount of calcium from SR (contractility effect)
2. Because of myosin heads getting phosphorylated
3. Because of increased calcium ATPase activity
459
Startlings law of the heart states that:
Anything that increases EDV will increase SV
460
Sympathetic motor neurons and epinephrine through B1 receptors act on ______ to do _____
Atria and ventricles to increase BOTH HR and SV
461
Parasympathetic neurons releases Ach that will bind to muscarinic receptors on the ____ that will only effect ____.
atria; HR
462
Describe parasympathetics motor neurons effect on stroke volume:
No effect on SV
463
At rest, the amount of ______> ______ so we know at rest our heart is overall under _____ influence.
Ach> NE; parasympathetic
464
Receptors on the atria are for the influence of ______, while the receptors on the ventricles are for _______.
HR; SV
465
Cardiac output is a function of _____ & _____.
SV and HR
466
What is the functional unit of cardiac muscle? What is the functional unit of skeletal muscle?
Sarcomeres
467
Since sarcomeres are the functional unit of both cardiac skeletal muscle; they both have _____ relationship
length/tension
468
What does having a length/tension relationship mean?
Means that there is a resting fiber length where you will have optimum tension
469
What happens if you move away from the resting fiber length?
You decrease the tension the muscle can generate
470
The stimulus for cardiac muscle is _____; while the stimulus for skeletal muscle is _____.
Intrinsic; extrinsic
471
Describe the calcium release in skeletal muscle:
100% SR
472
Describe the calcium release in cardiac muscle:
90% SR, 10% ECF
473
Contractile response to a single action potential:
muscle twitch
474
Describe the muscle twitch in cardiac muscle:
graded
475
What is the preferred drug of choice for dysrhythmia?
Beta-blockers
476
Describe the effects of each on CO:
1. Increasing Sympathetic activity
2. Increasing parasympathetic activity
3. Increasing movement
4. Decreasing HR
5. Increasing resting sarcomere length
6. Increasing BP`
1. Increase CO
2. Decrease CO
3. Increase CO
4. Decrease CO
5. Increase CO
6. Decrease CO
477
Explain why increasing movement would increase CO:
Due to skeletal muscle pump, which increases venous return, that will increase EDV and therefore increase SV
478
Explain why increasing resting sarcomere length would increase CO. What would happen if we decreased it?
Cardiac muscle sits at a less than optimum length, so by increasing resting sarcomere length, we are getting closer to optimum.
If we decreased it because we are already at a less than optimum length, this would move it further away from optimum.
479
Explain why decreasing BP would increase CO:
Because BP is the afterload on the heart. Anything that will decrease the load that the heart has to contract against will increase SV
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