Flashcards in Lecture Notes Deck (114):
1
What is systolic BP?
Pressure when heart contracts
2
What is diastolic BP?
Pressure when heart relaxes
3
Which portion of the cardiac cycle is longer and by how much?
Diastolic is 2x as long as the systolic
4
Formulas for MAP?
MAP=COxTPR
MAP= 2xdiastolic pressure + systolic pressure/3
5
Forumla for CO?
CO=SVxHR
6
What is the cardiac output?
Volume pumped by each ventricle per minute
7
What is stroke volume?
Volume pumped by each ventricle per heart beat
8
When is the 1st korotkoff sound heard?
At peak systolic pressure
9
What sound signifies diastolic pressure?
5th korotkoff sound
10
What is the total peripheral resistance?
Sum of resistance of all peripheral vasculature
11
Where are the baroreceptors?
Aortic arch and carotid sinus
12
What are the major resistance vessels?
Arterioles
13
What responds to acute changes in blood pressure?
Baroreceptors
14
What nerves transmit signals from the baroreceptors?
Carotid IXth CN
Aortic Xth CN
15
What do baroreceptors do when you stand up and MAP decreases?
Rate of firing decreases
16
What effect does a decrease in the rate of firing of baroreceptors have on the heart?
Vagal tone decreases
Sympathetic tone increases
17
What changes do the baroreceptors bring about to increase MAP?
increase HR, increase SV, increase TPR
18
Which 3 hormone systems regulate ECF fluid volume?
Rennin-Angiotensin-Aldosterone System
Atrial natriuretic Peptide
Anti diuretic hormone
19
Where is angiotensinogen released from?
Liver
20
Where is rennin relaxed from?
Kidney
21
What does rennin convert?
Angiotensinogen to angiotensin 1
22
What converts to angiotensin 1 to 2?
Angiotensin converting enzyme (ACE)
23
What does angiotensin II act on and what does this cause?
Adrenal cortex which releases aldosterone
24
What effect does aldosterone have?
Increase sodium and water reabsorption
Increased PV
Increased Blood pressure
25
What effect foes angiotensin II have?
Increase TPR
Increase ADH release
Increase thirst
26
What is the rate limiting step in the RAAS?
Rennin secretion
27
What is ANP released in response to?
Atrial distension
28
What does ANP cause?
Causes excretion of salt and water in the kidneys
29
What effect does ANP have on blood volume and BP?
Decreases them
30
What effect does ANP have on rennin release?
Decreases it
31
Where is ADH synthesised?
Hypothalamus
32
What stimulates the secretion of ADH?
Decreased ECF volume
Increased ECF osmolarity
33
What effect does AHD have?
Increases reabsorption of water
Increases ECF and Plasma Volume
Increases CO and BP
34
What is it called when the heat if able to beat in the absence of external stimuli?
Auto rhythmicity
35
Where does excitation of the heart originate?
In the sino atrial node
36
Where is the SA node located?
In the upper right atrium
37
How is the action potential generated in the SA cells?
Pace maker potential take the membrane potential to a threshold
38
What causes the pacemaker potential?
Reduction in K efflux
Slow Na influx
39
What causes the rising phase of the action potential?
Activation of voltage gated Ca channels
Resulting in Ca influx
40
What causes the falling phase of the action potential?
Activation of K channels
K efflux
41
How is excitation spread in atrium and ventricular muscle?
Via gap junctions
42
How does excitation in the heart spread?
SA node - AV node - Bundle of His - Left and right branches - Purkinje fibres
43
Where is the AV node located?
Base of right atrium
44
What is the only point of electrical contact between atrium and ventricles?
AV node
45
Where is conduction delayed?
AV node
46
What causes the rising phase of the ventricular muscle potential?
Na influx
47
What causes the plateau phase of the ventricular muscle potential?
Ca influx
48
What causes the falling phase of the ventricular muscle potential?
K efflux
49
What effect does sympathetic stimulation have on HR?
Increases it
50
What is the nerve supply to SA and AV nodes?
Vagus nerve
51
When is atropine used?
In bradycardia
52
What effect does vagal stimulation have on the slope of the pacemaker potential?
Decrease it
53
What effect does parasympathetic stimulation have on HR?
Slows it
54
What is the parasympathetic transmitter?
Acetylcholine
55
What is the sympathetic transmitter?
Noradrenaline
56
What are the 5 phases of the cardiac cycle?
1 - Passive filling
2- Atrial contraction
3 - Isovolumetric ventricular contraction
4 - Ventricular ejection
5- Isovolumetric ventricular relaxation
57
What % of ventricles fill by passive filling?
80%
58
What does P wave in ECG signal?
Atrial depolarisation
59
When does atria contact in relation to ECG?
Between the P wave and the QRS complex
60
When does ventricular contraction start in relation to the ECG?
After the QRS complex
61
What does T wave signal in ECG?
Ventricular depolarisation
62
What causes the first heart sound?
The closure of the mitral and tricuspid valves
63
What does S1 herald?
Beginning of systole
64
What causes the 2nd heart sound?
Closure of the aortic and pulmonary valves
65
What does S2 herald?
End of systole and beginning of diastole
66
What type of muscle is cardiac muscle?
Striated
67
How is muscle tension produced?
Sliding of actin filaments on myocin
68
What is the refractory period?
A period following an AP in which is it not possible to produce another AP
69
What does SV =?
EDV-ESV
70
What is a positive inotropic effect?
Increase in force of contraction
71
What determines end diastolic volume?
Venous return
72
What is a positive chronotropic effect?
Increase in HR
73
What does the starling law state?
The more the ventricle is filled with blood the greater the volume of ejected blood will be during systolic contraction
74
Will increase sympathetic discharge cause vasoconstriction or vasodilation?
Constriction
75
What are the capacitance vessels?
Veins - hold most volume during rest
76
Does angiotensin II cause vasoconstriction or vasodilation?
Vasoconstriction
77
How does sympathetics stimulation increase the HR?
Increases rate of firing by the SA node
Decreasing AV nodal delay
Increases force of contraction
78
4 chronic responses to exercise?
Decrease in sympathetic tone
Increase in parasympathetic tone
Cardiac remodelling
Decreased aterial stiffness
79
3 effects of nitrates on the vasculature?
Venorelaxation, arteriolar dilatation, increased coronary blood flow
80
Two examples of organic nitrates?
Glyceryltrinitrate and isosorbide mononitrate
81
2 unwanted effects of nitrates?
Repeated administration may cause diminished effect
Headaches
82
How do ACE inhibitors work?
Block the conversion of angiotensin 1 to angiotensin II
83
How do AT1 receptor antagonists work?
Block the agonist action of angiotensin II at AT1 receptors in a competitive manner
84
What effect does an ACE inhibitor have?
Causes venous and arterial dilatation - Decreasing TPR and so BP
85
2 adverse effects of ACE inhibitors?
May initially cause hypotension
Dry cough
86
What type of drugs would you prescribe if patient cannot tolerate cough of ACE inhibitor?
AT1 receptor antagonist
87
Contraindications of ACE inhibitors and AT1 receptor antagonists?
Pregnancy and bilateral renal artery stenosis
88
3 indications for ACE inhibitors and AT1 receptor antagonists?
Hypertension, cardiac failure, post MI
89
What does stimulation of beta 1 receptors cause?
Increase HR, Force and AV node condition velocity
90
What does stimulation of beta 2 receptors cause?
Bronchiole and blood vessel relaxation
91
How do Beta blockers treat angina?
Decrease myocardial O2 requirement
92
How do Beta blockers treat hypertension?
Reduce cardiac output, reducing rennin release from kidney
93
How do calcium antagonists work?
Prevents opening of L type channels and so limit calcium influx
94
Name 3 calcium antagonists?
Verapamil, amlodipine, diltiazem
95
Calcium antagonist in atrial fibrillation?
Verapamil
96
Uses of thiazide diuretics?
Mild heart failure, hypertension,
97
Uses of loop diuretics?
Acute pulmonary oedema
98
1 Example of thiazide diuretic?
Bendroflumethiazide
99
1 example of a loop diuretic?
Furosemide
100
1 example of an ACE inhibitor?
Lisinopril
101
1 example of an AT1 receptor antagonist?
Losartan - 'sartans'
102
2 examples of Beta blockers?
Atenolol, bisoprolol
103
How does Ivabradine work?
Selective blocker of HCN channels, used to slow heart rate
104
Effect of beta adrenoreceptor agonists on the heart?
Increase force, rate, CO and O2 consumption
Decrease cardiac efficiency
105
Name 2 beta adrenoreceptor agonists?
Adrenaline and dobutamine
106
Is propanolol a selective beta blocker or not?
Not selective
107
Name 2 selective Beta 1 blockers?
Metoprolol and atenolol
108
6 adverse effects of Beta blockers?
Bronchospasm, Aggravation of cardiac failure, bradycardia, hypoglycaemia, fatigue, cold extremities
109
Name one non selective muscarinic receptor antagonist?
Atropine
110
Clinical uses of atropine?
To reverse bradycardia following an MI,
111
Is digoxin positively or negatively inotropic?
Positively
112
What type of drug is digoxin?
Cardiac glycoside
113
What effects does digoxin have on the heart?
Slows SA node discharge, Slow AV node conduction, increases refractory period
114