PHYSIOLOGY + ETHICS Flashcards
1
Q
Highlight the 5 stages of atrial/ventricular depolarisation.
A
PHASE 0
fast Na channels open –> increased gNa+ –> rapid depolarisation
PHASE 1
fast Na channel close –> start of repolarisation
PHASE 2
Ca2+entry via dihydropyridine channels
PHASE 3
increased [Ca2+] –> stimulates K+ channels –> K+ efflux –> rapid repolarisation
+ Ca2+ channels close –> stop of deloparisation
PHASE 4
stable resting membrane potential
2
Q
What is the name of the channels responsible for the gradual drift in membrane potential in SA node depolarisation?
A
F-type Na+ channel
3
Q
What ion is responsible for the pacemaker potential going over the threshold in SA node depolarisation?
A
Ca2+
4
Q
What are the receptors and signal molecules involve in autonomous innervation of the heart?
A
SYMPATHETIC
noradrenaline, beta-1 receptor
PARASYMPATHETIC
acetylcholine, M2 receptor
5
Q
Attribute a chronotropic effect to an autonomic nervous system.
A
Sympathetic –> positive
Parasympathetic –> negative
6
Q
Describe the electrical conduction pathways of the heart.
A
SA node –> internodal tracts –> AV node –> bundle of His –> left/right bundle branches –> Purkinje fibres
7
Q
What is the intrinsic pacemaker of the heart?
A
sinoatrial node
8
Q
Where are the 2 delays in electrical conduction in the heart?
A
- AV node
- penetrating portion
9
Q
How many electrodes would you use in an ECG?
A
4 on the limbs + 6 across the chest
10
Q
What are the respective names of the molecules in cardiac muscles sarcoplamic reticulum and T-tubules tasked with storing calcium?
A
SR –> calsequestrin
T-tubule –> mucopolysaccharides
11
Q
What is the name of the process allowing release of calcium from the sarcoplasmic reticulum in cardiac contraction?
A
calcium-induced calcium-release
12
Q
Which electrical event is not shown/is masked on an ECG?
A
atrial repolarisation
13
Q
What are the two reasons why early premature cardiac contraction is very risky?
A
- no time for ventricle to fill up
- muscle hasn’t finished to relax –> diminished efficiency of contraction
14
Q
What percentage of the blood ejected during ventricular systole is ejected during the final 2/3 of the period of systole?
A
30%
15
Q
Give the average pulmonary BP value?
A
systolic = 30mmHg diastolic = 12mmHg
16
Q
What is the average stroke volume?
A
5L/min
17
Q
Define chronotropy, dromotropy, bathmotropy, inotropy, and lusitropy.
A
CHRONOTROPY rate of firing of SA node
DROMOTROPY conduction velocity of AV node
BATHMOTROPY degree of excitability of myocardium
INOTROPY degree of contractility of myocardium
LUSITROPY degree of relaxation of myocardium
18
Q
What percentage of the population has right coronary dominance?
A
80%
19
Q
Obstruction of which artery causes posterior infarct?
A
right coronary artery
20
Q
Give 3 other names to the ‘widow maker’ artery?
A
- artery of sudden death
- anterior interventricular branch
- left anterior descending artery
21
Q
Which type of infarct causes ventricular fibrillation?
A
anterior infarcts
22
Q
On which artery relies the principle of coronary dominance?
A
posterior interventricular artery
23
Q
Which two vessels are most commonly used in a CABG?
A
- internal thoracic artery
- saphenous vein
24
Q
Which cardiac vein accompanies the posterior interventricular artery?
A
middle cardiac vein
25
What percentage of coronary blood drains into the coronary sinus?
60%
26
When does the foetus' heart start beating?
day 21
27
List the 4 components of the cardiac conduction system.
- SA node
- AV node
- Bundle of His
- Purkinje fibres
28
Give the root values of presynaptic sympathetic fibers that are involved in innervation of the heart?
T1-T5/6
29
What are the root values of the vagus nerve?
T1-T4/5
30
At rest, how much of the blood in the coronary artery is 'used' by the heart?
>80%
31
Give the equation to calculate cardiac output. Give normal range values for adults for each of the components.
CARDIAC OUTPUT = STROKE VOLUME x HEART RATE
```
CO= 5-30L/min
SV= 70-140mL/min
HR= 70-200bpm
```
32
Which of the preload or the afterload of the stroke volume is respectively controlled by the Frank-Starling mechanism or the sympathetic system.
preload - Frank-Starling mechanism
| afterload- sympathetics
33
Describe the Frank-Starkling mechanism.
automatic balancing between cardiac output from the left side of the heart to the volume returning to the right side, that allows for automatic adjustment for small imbalances between the left and right ventricles
34
What is inotropic stimulation?
It is stimulation of the heart muscle cells by the ANS to increase or decrease tension i function of muscle length
35
Give one example of a compliant vessel, and one of a non-compliant vessel.
COMPLIANT
vein
NON-COMPLIANT
arteriole
36
How do you calculate mean arterial blood pressure?
MABP = diastolic pressure + 1/3(pulse pressure)
= diastolic pressure + 1/3 (systolic pressure - diastolic pressure)
= (2 diastolic pressure - systolic pressure)/3
37
What are the three factors influencing the magnitude of pulse pressure?
- stroke volume
- speed of ejection of stroke volume)
- arterial compliance
38
What is flow respectively directly and indirectly proportional to?
DIRECTLY
- pressure gradient in vessel
- radius of the vessel
INDIRECTLY
- viscosity of fluid
- length of the vessel
39
What are the three components of resistance, and which is the most important?
- viscosity of blood
- length of vessel
- radius of vessel --> most important (power of 4)
40
In a laminar flow, why is the velocity profile parabolic?
flow faster in middle most layers, because less friction than layers that touch the wall
41
When does Poiseuille's law not hold true?
turbulent flow
42
How do you know mathematically whether a flow is laminar or turbulent?
Reynold's number:
| Re= velocity of flow x radius of vessel/viscosity
43
What 4 factors make turbulence likely?
- high velocity flow
- large diameter vessels
- low blood viscosity
- abnormal vessel wall
44
What is the main feature of thixotropic fluids? Give two examples?
flow affects viscosity
- blood
- ketchup
45
In what instance would you like to artificially generate turbulence in the blood flow?
to take BP measurement
46
Give LaPlace's law.
Tension in vessel wall = distending pressure x radius of vessel
47
Give 2 good practical outcomes of LaPlace's law.
- arterioles can regulate blood flow
| - capillaries can be extremely thin (necessary for function) and still withstand the pressure
48
Give three actors in downstream regulation of blood flow.
- arterioles
- metarterioles
- precapillary sphincters
49
Give 4 examples of blood flow regulation types.
- hyperaemia (response to metabolic needs of tissues)
- flow autoregulation (response to changes in arterial pressure)
- vasomotion
- response to injury
50
What is released by endothelial cells in response to injury and what is its action?
endothelin-1 --> potent vasoconstriction
51
What are the two types of hyperaemia?
- active
| - reactive
52
How does the parasympathetic nervous system act on radius of vessels?
release of nitric oxide
53
What is the solution for long-term regulation of local blood flow?
angiogenesis
54
What are the names of the three types of capillaries?
- continuous
- fenestrated
- sinusoid/discontinuous
55
Differentiate between interstitium and interstitial fluid.
INTERSTITIUM
collagen and proteoglycan filaments
INTERSTITIAL FLUID
gel/fluid trapped amongst interstitium
56
What are colloids and crystalloids?
COLLOIDS
plasma proteins
CRYSTALLOIDS
low molecular weight molecules
57
Give the colloid and interstitial oncotic pressures. What direction does fluid flow in?
colloid oncotic pressure --> 28mmHg
interstitial oncotic pressure --> 5-8mmHg
direction: interstitial fluid --> capillaries
58
Give the hydrostatic pressures at the arterial end and the venous end of a capillary. What direction does fluid flow in?
ARTERIAL END
30-40mmHg
VENOUS END
10-15mmHg
direction: capillaries --> interstitial fluid
59
What are the Starling forces?
hydrostatic and oncotic pressures
60
What are the controlling functions of the lymphatic system?
- concentration of proteins in interstitial fluids
- control of volume of interstitial fluid
- control of interstitial fluid pressure
- immune response
61
Give the venous pressure range.
3-18mmHg
62
When standing, what is the MABP at level of the heart and at the level of the feet?
Heart --> 100mmHg
| Feet --> 190mmHg
63
Describe the mechanism behind orthostatic hypotension.
decreased venous return --> decreased cardiac output --> decreased BP
64
What are the 4 principles of medical ethics?
- autonomy
- beneficence
- non-maleficence
- justice
65
What are the 4 quadrants of medical ethics?
- medical indications
- patient preferences
- quality of life
- contextual features
66
Highlight the structure of a structured case analysis.
- summarize the case/problem
- state the moral dilemma
- state the assumptions that are being made
- analyze the case
- acknowledges other approaches and state the preferred approach with explanation
67
Why is integration and control of the heart and blood vessels necessary?
- to keep a relatively constant arterial BP
| - to control distribution of the total cardiac output
68
What are the 6 fundamental components of a reflex control system?
- internal variable
- receptors
- afferent pathways
- integrating center
- efferent pathways
- target effectors
69
Which of the aortic or carotid baroreceptors is more sensitive to drops in BP?
carotid
70
What nerves are associated with each of the baroreceptors?
aortic --> Xth cranial nerve
| carotid --> IXth cranial nerve
71
What is the primary purpose of baroreceptor reflex?
to reduce the minute-by-minute variations of arterial pulse
72
Where would you find cardiopulmonary receptors?
atria, ventricles, veins, pulmonary vessels
73
What is the Bainbridge reflex?
sympathetic-mediated reflex in response to increased blood in atria, causing increased heart rate and increased contractility
74
Give an example of when the Bainbridge reflex would happen.
tachycardia during childbirth
75
What are the three regions of the medullary cardiovascular control center?
- sensory area
- lateral portion (sympathetic source)
- medial portion (parasympathetic source)
76
Describe the CNS ischaemic response.
- increase in peripheral vasoconstriction
- sympathetic stimulation of the heart (increase in rate and stroke volume)
- large increase in systemic arterial pressure
77
Give 6 reasons why basic errors in medicine happen.
- stress
- fatigue
- covering for colleagues
- professional culture
- feeling that decisions must be made alone
- unable to admit to uncertainty
78
What is the duty of candour?
a statuory obligation on doctors and nurses so they are open with patients about mistakes
79
What are the 4 things you should do according to the GMC's guidance on duty of candour when a mistake is made?
- tell the patient
- apologize
- offer appropriate remedy/support
- explain the short and long-term effects
80
What are the three possible negative outcomes in response to errors or inadequate care?
- negligence
- NHS complaints procedure
- GMC review
81
What must the claimant establish in a negligence legal case?
- they are owed a duty of care by defendant
- the defendant breached that duty by failing to provide reasonable care
- causation and proximity
82
What are the two tests that describe reasonable care?
Bolam and Bolitho tests
83
Give 6 ways in which failures of the current system are being addressed.
- dedicated centers
- requirement to retrain
- data collection of incidents
- improved instrument design
- protocols and guidelines
- checklists
84
What are the two primary determinants of long-term regulation of BP?
- renal output curve for salt and water
| - level of salt and water intake
85
What is the physiological factor that influences the set-point of arterial pressure?
water and salt intake
86
What is ADH released in response to?
- increase in osmotic pressure
- hypovolaemia
- hypotension
- angiotensin II
87
What is renin released in response to?
- sympathetic nerve activation
- renal artery hypotension
- decreased sodium in kidney distal tubule
88
What are the respective roles of angiotensin II and aldosterone?
ANGIOTENSIN II
increases totale peripheral resistance + constricts renal arteries
ALDOSTERONE
increases sodium and water reabsorption
89
When is atrial-natriuretic hormone release? What does it do?
response to stretch of the atria
counteracts the effects of the RAAS system
90
Classify shock.
```
class 1 - 10-15% blood loss
class 2 - 15-30% blood loss
class 3 - 30-40% blood loss
class 4 - >40% blood loss
```
91
What is the immediate response to hypovolaemia (class 1 shock)?
- decrease in stroke volume counteracted by stroke volume
- increase in heart rate
- drop in cardiac output counteracted by stroke volume and heart rate reactions
- increase in total peripheral resistance
- sudden drop in MABP counteracted by increase in cardiac output and total peripheral resistance
92
What does the later response to hypovolaemia involve?
- arteriolar constriction (for temporary redistribution of flow)
- decreased renal blood flow
- thirst
93
Give two example of resuscitation fluids
- colloids
- Hartmann's
- blood
94
Give the Fick principle.
cardiac output = rate of O2 consumption (mL/min) / arteriovenous O2 difference (mL/L)
95
What determines the window of coronary flow?
aortic pressure > ventricular pressure
96
What are the respective effects of adrenaline and noradrenaline on skeletal muscle arterioles?
ADRENALINE
vasodilation
NORADRENALINE
vasoconstriction
97
What triggers the contraction of pre-capillary sphincters during the white reaction?
myogenic contraction, induced by stretch activated calcium channels
98
Why does the white reaction fade after a few minutes?
local factors cause vasodilation
99
What is the relation between the triple response and anaphylaxis
anaphylaxis is a widespread triple response equivalent
100
What are the steps of the triple response?
- flush within 30s on area of contact
- irregular diffuse flare in surrounding area
- wheal
101
Describe the Vasalva maneuver.
deep breath, then exhale out moderately forcefully against a closed airway
102
What is the New York Association classification of Heart failure based on?
severity
103
In which type of heart failure is the ejection fraction impaired?
systolic ventricular heart failure
104
Give 4 reasons for diastolic ventricular dysfunction.
- impedance of ventricular expansion
- increased wall thickness
- delayed diastolic relaxation
- increased heart rate
105
Give 3 conditions that can cause left ventricular dysfunction.
- hypertension
- acute MI
- aortic or mitral valve stenosis or regurgitation
106
What are the 4 compensatory mechanisms that are not adapted to cope with heart failure?
- sympathetic inotropy
- RAAS system
- Frank-Starling mechanism
- fluid movement (Starling forces)
107
Which adrenoreceptors do not get desensitised in heart failure and make the situation worse?
alpha receptors
| increase total peripheral resistance --> stronger afterload --> heart has to beat harder
108
How are aldosterone and angiotensin II involved in heart failure?
inflammatory response --> deposition of fibroblasts and collagen in the ventricles --> increase in stiffness and decrease in contractility of heart --> myocardial remodelling + progressing dysfunction
109
What are the 4 strategies of treatment?
- increase cardiac contractility
- decrease preload and/or afterload
- inhibit RAAS
- prevent inappropriate increase in heart rate
