Heart Flashcards
1
Q
How much of blood is dropped through the AV valves?
A
70%
2
Q
Where are valves?
A
Veins & lymphatic system
3
Q
Which side of heart must contract against higher pressure?
A
Venous side
4
Q
What keeps the AV valves from blowing back open into the atria?
A
Papillary muscles & chordae tendineae
5
Q
Why do AV valves open?
A
Pressure in atria larger than pressure in ventricle
6
Q
pH of above 7.45 is considered?
A
Alkalosis
7
Q
pH below 7.35 is considered
A
acidosis
8
Q
Cardiac muscle
A
Branched myofiber
Uninucleated
Intercalated disc w/ gap junctions
Functional syncytia
9
Q
Primary pace maker of heart?
A
Sinoatrial node
10
Q
Secondary pace maker
A
Atrioventricular node
11
Q
Where do nerve impulses travel after atrioventricular node
A
Bundle of Hiss –>Purkinje fibers
12
Q
Where does contraction of the heart start?
A
Apex
13
Q
What causes automaticity of the sinoatrial node?
A
Unstable resting potential
14
Q
What causes opening of Na+ channels?
A
Rapid repolarization of potassium channels
15
Q
HCN channels
A
cause unstable resting potential
16
Q
What are HCN channels sensitive to?
A
Cyclic nucleotides (cAMP ) causes by epi/norepi Increases chronotropic effect)
17
Q
What causes rapid depolarization of membrane?
A
Fast Ca2+ channels opening
18
Q
What is a normal heart rate?
A
72 bpm
19
Q
Where does pacemaker potential start (mV)?
A
-50 mV
20
Q
What is the effect of sympathetic innervation of the heart?
A
Greater opening of HCN channels
Increase heart rate
21
Q
What is the effect of parasympathetic innervation on heart?
A
ACh promotes opening of K+ channels
Causes resting membrane slope to be flatter & decrease heart rate
22
Q
What does endurance training do to heart rate?
A
Increase parasympathetic innervation
23
Q
Where is the cardiac control center
A
Medulla
24
Q
Cardiac muscle action potential
A
Stable around -80 mV
Up to +20 mV
25
What causes myocardial action potential to stay refractory?
Calcium plateau
| Keeps potential up in positive range, no repolarization
26
How long is the cardiac action potential?
250 milliseconds
27
Contraction time of myocardial cells
300 ms
28
Action potential & contraction of skeletal muscle
1-2 msecs
| 10-50 msecs
29
Extraparaventricular contraction
Contract quickly, but then long compensatory pause before 2nd contraction
Needed to decrease blood pressure & need another heart beat
30
Depolarization of atria
P wave
31
QRS wave
repolarization of atria & depolarization of ventricle
32
T wave
Repolarization of ventricle
33
U wave
Repolarization of bundle of Hiss
34
What does a depressed ST segment indicate?
Lack of blood flow to ventricular muscle (lack of O2 delivery)
35
Ventricular fibrillation
Random action potentials, could be result of ectopic foci- lose coordination
36
What kind of action potential does the EKG show?
Compound action potential
37
What are the waves of the atria called?
a, c, v
38
What causes the first heart sound?
AV valves
39
What is the time period in between mitral valve closure & semilunar valve opening?
Isovolumic contraction
40
What causes the dichrotic notch?
Semilunar valves closes & aortic volume can't flow back into the heart & pressure builds to flow back to systemic circulation
41
How long does the isovolumic relaxation last?
Until pressure in the ventricle falls below that in the atia
42
What is cardiac output
Cardiac rate x Stroke volume
43
Total average blood voume
5.5 L
44
Cause of v wave (in atria)
venous return to the atria
45
Where does ventricular pressure end at?
0 mmHg
46
Where would you measure pressure of 120/80?
Aorta?
47
What do pressure curves look like on the right side of the heart?
Much less pressure, but exactly the same
48
When does the heart receive blood from the coronary arteries?
During diastole
49
What shortens during a high heart rate?
Diastole time period
| Less blood getting back to heart
50
What would the right side of the heart pressure look like?
25/8 mmHg
51
What kind of effect on the heart is sympathetic innvervation?
Chronotropic & Inotropic bc of synapses en passant
52
What effect does temperature have on heart rate?
Increased with increased temperature
53
Hyperkalemia causes what in the heart?
Decreased force & rate
54
Hypokalemia causes what in the heat?
Cardiac arrhythmias
55
Increased calcium effect on heart?
Increase mechanical action, but slow down bc of divalent cation
56
What do cardiac glycoside sugar steroids do to the heart?
Increase strength
57
Cardiac output
Volume of blood pumped per minute by each contraction
| CO =SV + CR
58
Strove volume
amount of blood pumped out in a contraction
59
How much blood is in resting stroke volume?
70 mL
60
What is resting cardiac output?
5 L/min
| 70 mL x 72 bpm
61
What drives cardiac output?
Mean Arterial pressure= 100 mmHg
62
How long does it take each ventricle to pump the total amount of blood?
1 minute
63
How much blood is left in the ventricle after systole?
65 mL
64
What affects end diastolic volume?
Venous filling pressure- increase
Ventricular filling time- increase
Ventricular wall distensibility-increase
Pressure of atrial contraction--Increase
65
What affects systolic volume?
```
Ventricular contraction- decrease ESV
Lower pulmonary pressure-
Increase
Higher arterial pressure-
Increase (takes more pressure to pump to higher pressure)
```
66
Increasing cardiac out put increases
Blood pressure
67
As end diastolic volume increases, what also increases?
Stroke volume
68
As sympathetic innervation increases on heart, what also increases?
Stroke volume due increased contractility
| Inotrooic effect due to more Ca2+ available
69
What happens to end diastolic volume when you lay down?
It goes up, decreased drag down from skeletal muscle pumps
70
What happens to end diastolic volume when you stand up?
It goes down
71
Where are the baroreceptors
Bifuraction of carotid artery
72
What do baroreceptors detect?
Blood pressure
73
Mean arterial pressure
Diastolic pressure + 1/3 pulse pressure
74
Pulse pressure
Systolic- diastolic
75
Length-tension in myocardial muscle
Frank-starling mechaings
76
What causes the increase in stroke volume to increase EDV?
Optimal length of sarcomere strucutre as the myocardial cells are stretched out
77
What causes aortic diastole pressure to go up?
Atherosclerosis of the arteries
78
What causes aortic systole pressure to increase?
Arterio/Atherosclerosis of the arteries
79
Why can't pulse be taken from veins?
Capillaries dampen any feel of ventricle pressure out into the aorta
80
Why can you use Kortocoff sounds?
Only hear noise when there is not smooth, laminar flow (caused by increased pressure)
81
Which vessels are the primary resistance vessels?
Arterioles
82
What would polycythemia do to blood pressure?
Increase viscosity, increase blood pressure
83
What is used to measure antagonistic relations on heart?
RR variation
84
How much blood volume is in the veins?
2/3 blood volume
85
What kind of vessels are the veins?
Capacitance vessles
86
What does breathing affect?
Increase pressure on veins so that venous return is increased
87
When standing, the skeletal muscle does what?
Increases venous return
88
What affect does sympathetic nerve stimulation have to venoconstrict?
Venoconstriction drives blood to more high pressure arteriole side -->increased venous pressure increases EDV
89
What receptors cause sympathetic vasoconstriction of smooth muscle/skin
Norepi & Alpha adrenergic
90
What causes sympathetic vasodilation is skeletal muscles?
Epinephrine & B adrenergic receptors
91
What causes release of ADH
High blood osmolarity
92
What other affect does Angiotensin II have besides aldosterone?
Increase vasoconstriction to increase blood pressure
93
What is the pressure on the arterial side of capillary bed?
37 mmHg
94
What is the pressure on the venous side of capillary bed?
17 mmHg
95
Where does blood pressure drop the most?
Arterioles
96
Why does pressure go back up in the veins?
Capacitance vessels
97
Where is blood flow the slowest?
Capillaries
98
Poisuelle's Law
Q= pi(P)r^4/8nl
99
Why is the valsalva maneuver dangerous?
Increases mean arterial pressure while compressing vena cava (no venous return)
100
Arterioles are controlled mainly by what autonomic control?
Sympathetic control
101
What happens during low concentration of epinephrine in arterioles?
Vasodilation
102
What happen during high concentration of epinephrine in arterioles?
Alpha receptors to cause vasoconstriction
103
What happens during increased mechanical stretch on the arteriole?
Harder contraction more forcefully
104
What metabolites result in vasodilation?
Decreased O2
Increased CO2
Increased H+
Inc in K+
105
What are vasodilators
Endothelial Relaxing factor
NO
Histamine
106
How much of blood is in skeletal muscle during exercise?
80-85%
107
What happens to blood during exercise?
Stealing phenomenon
108
What governs fluid movement?
Starling Forces
109
Starling forces equation
Pc +(pi)i - Pi + (pi)p
110
Force in capillaries of starling forces?
```
Pi= hyrdostatic pressure of interstitial forces= 1
(pi)p= colloid osmotic pressure of blood plasma = 25
```
111
Forces out in capillaries of Starling forces?
```
P(c)= hydrostatic pressure of capillary (37 or 17)
pi(i)= colloid osmotic pressure of interstitial fluids (0)
```
112
How much net filtration on arteriole side
11 mmHg
113
How much net absorption on venous side
-9 mmHg
114
What starling force increases during a sprain?
(pi)I =colloid osmotic pressure out
115
Active hyperemia
During active contractions during exercise
116
Reactive hyperemia
Taking off tourniquet & reaction- reaction to low blood flow
117
Heart rate less than 60 bpm
Bradycardia
118
Heart rate greater than 100 bmp
Tachycardia
119
Hyperemia
Increased tissue blood flow
