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Medsci Exam > cardio > Flashcards

cardio Flashcards

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1
Q

What percentage of blood is found in the systemic system?

A

84%

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2
Q

What percentage is found in the pulmonary system?

A

9%

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3
Q

How does an action potential propagate through an atria?

A

through gap junctions in the intercalated discs of atrial muscle fibres

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4
Q

what is the speed of the first stage of the cardiac action potential?

A

slow 0.5 m/s

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5
Q

Why does the rate of ejection slow down during ventricular systole?

A

as the myocytes begin to run out of strength/ ability to shorten in the ventricle

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6
Q

Which blood vessel has the highest compliance?

A

elastic arteries

therefore lowest elastance

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7
Q

what is another name for elastic arteries?

A

conducting arteries

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8
Q

What is the size of an elastic artery?

A

more than 1cm

finger size

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9
Q

What is the function of elastic arteries?

A

store bolus of blood during ejection
SMOOTHEN OUT the pulsatile flow of blood from the ventricle
push blood out into the arterial tree via Elastic Recoil

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10
Q

What distance after the heart do elastic arteries go for?

A

first 15 cm

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11
Q

How many sheets of elastic fibres in tunica media can be found in elastic arteries?

A

up to 50

+ a few smooth muscle fibres

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12
Q

What are the most abundant arteries?

A

muscular arteries

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13
Q

What is the size of muscular arteries?

A

pencil –> pin

10mm –> 1 mm

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14
Q

Where are the tunica’s most distinct?

A

muscular arteries

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15
Q

What is in the tunica externa of muscular arteries?

A

elastic and collagen fibres

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16
Q

What is in the tunica media of muscular arteries?

A

smooth muscular 3-40 sheets
connective tissue
elastic fibres

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17
Q

What is located within the tunica interna / intima?

A 
inner elastic lamina (thin sheet of elastic fibres)
basement membrane (physical support)
endothelium
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18
Q

How many sheets of smooth muscle are in muscular arteries?

A

3-40 sheets

hence 10mm –> 1mm diameter

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19
Q

What is the function of muscular arteries?

A

bulk flow
bulk tuning
distributes blood around the body at high pressure

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20
Q

Where is the site of final fine tuning?

A

arterioles

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21
Q

What is the thickness of arterioles?

A

100 microns - 10 microns

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22
Q

Besides normal what is the function of arterioles?

A

to protect capillaries

impact TPR and mabp

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23
Q

How many sheets of smooth muscle are in arterioles?

A

3-1 of circular smooth muscle

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24
Q

What causes edema?

A

when the rate of filtration is larger than the rate of reabsoprtion
leads to swollen tissue
lower limbs when standing too long

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25
What are capillaries made out of?
single endothelial cell layer External BM NO SM NO CT
26
What is the function of venules?
site where WBC leave during inflammation and infections- leave to attack pathogen in connective tissue alongside them WBC (neutrophils) stick to side of vessel due to slow flow small venules= single layer endothelium and CT (CT + capillary) large venule= single layer of smooth muscle
27
What is a small venule made out of?
single layer endothelium + CT | capillary + CT
28
What is a large venule made out of?
Single layer of Smooth muscle
29
What is the breakdown of blood in the systemic circuit?
``` 84% in total systemic circuit - 64% in systemic veins and venules (reservoir) 13% in systemic arteries and arterioles 7% systemic capillaries + 7% heart 9% pulmonary circulation ```
30
What is the compliance of vein walls?
very compliant
31
What is the structure and function of veins?
similar to muscular arteries but with just a lot less muscle and connective tissue -venous pump aiding venous return back up to the heart
32
What does the left artery do and how many branches?
Two branches | supplies front and left of the heart
33
What does the right artery do and how many branches?
one branch | supplied right and back of the heart
34
What are anastomes?
coronary artery-to artery junctions | between small penetrating branches of main coronary arteries
35
What are the artery to artery junctions between small penetrating branches of main coronary arteries?
anastomes
36
What can ischemia cause?
angina | -due to death of the tissue and pain in breathing
37
What can cause angina?
ischemia
38
What can severe angina cause?
death/infarction of LOCAL area of myocardium
39
What is the advantageous function of anastomes?
they can widen when there is a local ischaemic region, allowing the ischaemic region to recieve blood supply from DISTANT ARTerioles
40
What happens to distant arterioles when there is angina in the coronary arteries?
anastomes widen and this allows areas with ischaemia due to a diseased coronary artery to receive blood from DISTANT ARTIERIES
41
What is a thrombosis?
a broken free blood clot
42
What is a broken free blood clot called?
thrombosis
43
What do you measure to get blood pressure?
brachial (arm) artery
44
What is the units for cardiac output?
The amount of blood that is ejected into the aorta per minute Lmin-1
45
What is venous return?
the quantity of blood returning to the heart from the vasculature per minute Lmin-1
46
What is stroke volume?
the quantity of blood that is pumped into the aorta EACH CONTRACTION mL/beat EDV-ESV
47
What is heart rate?
the number of beats per minute | bpm
48
Why does the kidney receive such a large portion of cardiac output?
20-25% of CO at rest 1L of blood through kidney alone allows the filtering of waste and CO2 out of the blood stream to be rapid
49
What is CO at rest?
75 bpm x 70mL | 5.25L
50
What is CO after exercise?
150 bpm x 130 mL | 19.5
51
What is the relationship between myocardial infarction and cardiac reserve?
decreased cardiac reserve decreased ability to increase CO upon exercise demand of tissues increased, but DECREASED ABILITY TO SUPPLY decreased CO can lead to heart failure
52
What is an average person's cardiac reserve?
4-6x CO at rest
53
What is a fit person's cardiac reserve?
7-8x CO at rest
54
What is the max HR?
180-200 bpm
55
What is the max SV?
150mL
56
What is the key word for preload?
STRETCH stretching myocytes augments/stimulates the AMOUNT OF CROSS BRIDGE FORMATION increased EDV
57
What is the key word for contractility?
forcefulness the forcefullness at which the ventricle squeezes down on the volume of blood starlings law of the heart decreased ESV inotropic agents- positive can increase Ca2+ inflow
58
What are inotropic agents related too?
contractility
59
What does a negative inotropic agent do?
K+ | decreases HR and decreases contractile force
60
What must happen with after load?
aortic/arterial blood pressure must be exceeded
61
What is the intrinsic regulation of the heart?
degree of stretch of the myocardial fibre at the end of diastole
62
What is the extrinsic regulation of the heart?
autonomic nervous system activity | circulating levels of hormones
63
What type or regulation is hormone levels?
extrinsic regulation
64
what type of regulation is the autonomic nervous system?
extrinsic regulation
65
What type of regulation is the length of cardiac muscle fibres at the end of diastole?
intrinsic regulation
66
What does the frank starling law of the heart ensure?
prevents damming of the heart ensures output = input -the energy of contraction is a function of the initial length of the myocardial fibres (sarcomere length causes force generation)
67
How do you count EF?
cardiac echoes
68
What two things determine blood flow?
going --> pressure difference (Gradient) | resistance
69
What is the equation for BP?
CO x TPR
70
Does BP ever fall to zero?
No because of the vasculature
71
What are the three factors affecting resistance?
radius - inverse relationship blood viscosity - directly proportional relationship vessel length - directly proportional relationship
72
What is the law which talks about resistance?
pousille's law; 8nL/pixr^4
73
Is oxygen a vasoconstrictor or a vasodilator?
O2 is a vasoCONSTRICTor
74
Is carbon dioxide a vasodilator or a vasoconstrictor?
vasoDilator
75
What is an example of a hormonal factor that is a vasoconstrictor?
Angiotensin II | -focus of drug therapy to decrease it's levels
76
What are the four factors affecting vascular tone?
sympathetic nerve activity hormonal factors metabolites intrinsic factors (NO)
77
What is Angiotensin II in relation to the heart?
hormonal factor which affects vascular tone vaso constrictor target to reduced angiotensin II levels in high BP patients
78
What is an intrinsic factor which regulates vascular tone?
Nitrous Oxide | vasoDILATOR
79
What are the three higher brain centres?
cerebral cortex limbic system hypothalamus
80
What is the function of chemo receptors?
monitors blood acidity | CO2, O2 and H+
81
What are the two outputs by the sympathetic nervous system?
vasomotor nerves | cardiac accelerator nerves
82
What is the relationship between cardiopulmonary and arterial baroreceptors?
cardio pulmonary receptors are relatively more sensitive to changes in blood volume When there is a 1L loss of blood volume it will be primarily sensed be the cardiopulmonary receptors. But since this is such a significant loss, it will lead to a decent drop in systemic blood PRESSURE which will be sensed by the arterial baroreceptors (hence pressure) they will work together in a symbiotic relationship
83
What is feeling faint/light headed an example of?
decreased blood pressure
84
What is the order of sympathetic nerve and neurotransmitter release to smooth muscle?
cholinergic -> nicotinic receptor (ACh) --> adrenergic --> adrenergic receptor (NE and E) --> smooth muscle, glands, cardiac
85
What is the order of sympathetic nerve and neurotransmitter release to sweat glands?
cholinergic --> nicotinic receptors (ACh) --> muscarinic --> muscarinic receptors (ACh) --> sweat glands
86
What is the order of para sympathetic nerve and neurotransmitter release to smooth muscle?
cholinergic --> nicotinic (ACh) --> muscarinic --> muscarinic receptors (ACh) --> smooth muscle, cardiac, glands
87
What 3x areas of the body does the autonomic nervous system innervate?
smooth cardiac glands
88
What happens after a decrease in blood pressure?
decreased STRETCH of baroreceptors in aortic arch and carotid sinus --> decreased firing of baroreceptors in aortic arch and carotid sinus --> sensory neurons --> cardiovascular centre in the medulla oblongata --> increased stimulation/output of sympathetic nerve (NE and E) and decreased stimulation/output of parasympathetic nerve (ACh)
89
On average what is MABP?
100mmHg

Medsci Exam (4 decks)

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