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Cardiovascular system > Physiology > Flashcards

Physiology Flashcards

(59 cards)

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1
Q

What are the functions of the CVS?

A

Bulk flow
Thermoregulation
Protection
Fluid balance

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2
Q

What are is the arrangement of most vascular bed?

A

Parallel

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3
Q

How is flow calculated?

A

Change in pressure/resistance

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4
Q

What controls pressure?

A

MAP- CVP

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5
Q

What controls resistance?

A

Radius

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6
Q

What are resistance vessels?

A

Restrict and dilate to alter blood flow
Arterioles

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7
Q

What are capacitance vessels?

A

Hold and store blood
Venules and veins

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8
Q

What are exchange vessels?

A

Capillaries

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9
Q

What are the features of excitation- contraction coupling in cardiac muscle?

A

Functional syncytium- intercalated discs
- Gap junctions (electrical connection)
- Desmosomes (physical connection)
Long action potential (250ms)
Pacemaker cells have unstable resting membrane potentials

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10
Q

What are the features of non-pacemaker cell action potential?

A

RMP- high resting PK+
Depolarisation- increased PNa+
Plateau- decreased PK+, Increased PCA2+ (L)
Repolarisation- Increased PK+, Decreased PCa2+ (L)

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11
Q

What are the features of pacemaker cell action potential?

A

Pacemaker potential:
- Decrease in PK+
- Early increase in PNa+
- Late increase in PCa2+ (T)
Action potential:
- Increase in PCa2+ (L)

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12
Q

What are the components of the special conducting system?

A

SA node- pacemaker
Annulus fibrosis- non conducting ring of tissue
AV node- delay box
Bundle of His
Purkinje fibres

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13
Q

What does each part of the ECG mean?

A

P= atrial depolarisation
QRS= ventricular depolarisation
T= ventricular repolarisation

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14
Q

What do standard limb leads show?

A

Events in the frontal pain

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15
Q

What does SLL I show?

A

Left arm wrt right arm

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16
Q

What does SLL II show?

A

Left leg wrt right arm

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17
Q

What does SLL III show?

A

Left leg wrt left arm

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18
Q

What does PR interval show?

A

Time for atrial to ventricular depolarisation
Due to transmission through AV node

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19
Q

What does QRS interval show?

A

Time for whole of ventricle to depolarise

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20
Q

What does QT interval show?

A

Time spent while ventricles are depolarised

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21
Q

Why is R wave biggest in SLL II?

A

Main vector of depolarisation is in line with axis of recording

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22
Q

What are the augmented limb leads?

A

aVR- right arm
aVL- left arm
aVF- foot

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23
Q

What are the precordial chest leads?

A

V1-V6

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24
Q

What are the steps of the cardiac cycle?

Study These Flashcards
A
  1. Late diastole
  2. Atrial systole
  3. Isovolumic ventricular contraction
  4. Ventricular systole
  5. Isovolumic ventricular relaxation
25
What does mitral valve closure indicate?
Start of systole
26
What does aortic valve closure indicate?
Start of diastole
27
What is end diastolic and end systolic volume?
EDV= 140ml ESV= 60ml
28
What is stroke volume?
Volume of blood pumped out with each beat of the heart EDV-ESV= 80ml
29
What is ejection fraction?
Stroke volume as a fraction of the end diastolic volume 80/140= 2/3
30
What is 1st heart sound?
Closure of AV valves (mitral and tricuspid)
31
What is 2nd heart sound?
Closure of semilunar valves (aortic and pulmonary)
32
What are the 2 causes of abnormal heart sounds?
Stenosis Regurgitation
33
What regulates heart rate?
Sympathetic and parasympathetic
34
What regulates stroke volume?
Preload Afterload Contractility
35
What is preload?
Length of muscle fibre before contraction Preload is affected by EDV
36
What is afterload?
Load against which muscle tries to contract Afterload affected by TPR
37
What is contractility?
Strength of contraction Affected by sympathetic nervous system acting on B1 receptors on myocytes
38
What controls cardiac output?
Hr x SV
39
Why does CO increase in exercise?
HR increases (SNS) Contractility increases (SNS) Venous return increases (venoconstriction) TPR falls (arteriolar dilatation)
40
What is the function of elastic arteries?
Dampen down pressure variations Pressure reservoir
41
Why does pressure fall through the vascular tree?
Arteries- 95 to 90mmHg Arterioles 90- 40mmHg Capillaries- low pressure Veins- 20- 5mmHg
42
Where is velocity of blood fastest?
Aort anad vena cava Slowest in capillaries
43
What influences flow in veins?
Gravity Skeletal muscle pump Respiratory pump Venomotor tone Systemic filling pressure
44
What are the parts of the anticlotting mechanism?
Inhibit platelet aggregation - Stop blood contacting collagen - Produce prostacyclin and NO Inhibit thrombin production - Tissue factor inhibitory pathway - Thrombomodulin - Heparin Activate plasmin from plasminogen to digest the clot - Tissue factor plasminogen activator (t-PA)
45
What are the different structures of capillaries?
Continuous- no clefts/pores (brian) Fenestrated- clefts and pores (intestine) Discontinuous- clefts and massive pores (liver)
46
What does MAP =?
MAP= CO X TPR
47
How is MAP controlled?
Local mechanisms Central mechanisms- maintain TPR
48
What are the local mechanisms for controlling MAP?
Active hyperaemia (metabolic activity increases flow) Pressure autoregulation (reduced MAP, decreases flow causing dilatation) Reactive hyperaemia (occlusion of blood supply increases flow) Injury response (delivers WBCs to area)
49
What are the central mechanisms for controlling MAP?
Neural- sympathetic NS Hormonal- adrenaline binds to a1 receptors causing constriction
50
What is the arterial baroreflex?
Stretch receptors in aortic arch and carotid sinus Firing rate of baroreceptors indicates MAP
51
What nerves are involved in arterial baroreflex?
Aortic arch- vagus nerve Carotid sinus- glossopharyngeal nerve
52
What is valsalva manouvre?
Forced expiration against a closed glottis
53
What are the steps to Valsalva manoeuvre?
1. Increased thoracic pressure transmitted through aorta 2. Reduces venous return which reduces MAP 3. Baroreceptors detect MAP 4. Reflex increase in CO and TPR 5. Venous return restored so SV increases
54
What organ mediates long term control of BP?
Kidneys
55
How do the kidneys regulate plasma volume?
Renal counter current system creates high osmolarity outside collecting duct Increase collecting duct permeability = water reabsorption and retained plasma volume Decrease collecting duct permeability= water retained and reduced plasma volume
56
What hormones regulate control of PV?
Renin- angiotensin-aldosterone system Antidiuretic factors Atrial natriuretic peptide and brain natriuretic peptide
57
What is Renin- angiotensin-aldosterone system?
Renin converts angiotensin I into angiotensin II - Stimulates aldosterone release which increases Na+ reabsorption (increased PV) - Stimulates ADH release from pituitary which increases collecting duct permeability - Vasoconstrictor so increases MAP
58
What is antidiuretic hormone?
Synthesised in hypothalamus and released from pituitary Release triggered by decreased blood volume, increased osmolarity and circulating angiotensin II - Increases permeability of collecting duct - Vasoconstrictor so increases MAP
59
What is atrial natriuretic peptide and brain natriuretic peptide?
Produced from myocardial cells in atria and ventricles Released by distention of atria and ventricles - Increase excretion of Na+ - Inhibit renin release - Reduce MAP Therefore, decrease PV and BP

Cardiovascular system (17 decks)

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