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CARDIOVASCULAR > Physiology > Flashcards

Physiology Flashcards

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1
Q

What is meant by autorhythmicity?

A

The capability of the heart to beat rhythmically in the absence of external stimuli as the electoral signals are generated within the heart itself

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2
Q

What are the three layers of a blood vessel?

A

Tunica intima, tunica media, tunica adventitia

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3
Q

Describe the composition of the tunica intima

A

Squamous epithelial cells
basal lamina
connective tissue

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4
Q

Describe the composition of the tunica media

A

Smooth muscle

Elastic tissue

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5
Q

Describe the composition of the tunica adventitia

A

Connective tissue

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6
Q

Which germ layer is the heart derived from?

A

The mesoderm

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7
Q

During embryology how many branches of the aorta are there initially?

A

6 main branches

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8
Q

What is the purpose of the vitelline ducts?

A

Drain the yolk sac during development

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9
Q

Do umbilical veins carry oxygenated or deoxygenated blood?

A

Oxygenated

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10
Q

Describe some of the special features of the coronary circulation which make it so efficient

A

High capillary density
High basal blood flow
High oxygen extraction (75%)

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11
Q

Where do the coronary arteries drain into?

A

The RA via the coronary sinus

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12
Q

When does peak flow in the coronary circulation occur?

A

During diastole because when the heart is relaxing the vessels are not compressed

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13
Q

What anastamoses allows cerebral perfusion to be maintained even if one of the arteries is obstructed?

A

The anastomoses of the internal carotids and vertebral arteries, forming the Circle of Willis

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14
Q

What effect does hypoxia have in the pulmonary circulation?

A

Hypoxia causes vasoconstriction which diverts blood away from poorly ventilated areas of the lung

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15
Q

What feature of the pulmonary circulation protects against oedema?

A

Absorptive forces exceed filtration

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16
Q

What makes resting blood flow low in skeletal muscles?

A

Vasoconstrictor tone

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17
Q

What effect does adrenaline have on skeletal muscle circulation?

A

Adrenaline causes vasodilation of blood vessels in skeletal muscle which increases blood flow

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18
Q

Does decreased blood pressure cause increased of decreased baroreceptor discharge?

A

Decreased blood pressure causes decreased baroceptor discharge

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19
Q

What effect does decreased baroreceptor discharge due to decreased BP have on sympathetic activity and constrictor tone?

A

Decreased baroreceptor discharge causes increased sympathetic activity and increased sympathetic tone

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20
Q

What effect does decreased baroreceptor discharge have on vagal activity?

A

Decreased baroreceptor discharge causes decreased vagal activity which has a similar effect as increasing sympathetic activity (it increases heart rate and cardiac output)

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21
Q

What effect does decreased blood volume have on filtration and reabsorption?

A

Decreased blood volume causes decreased filtration and increased reabsorption

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22
Q

What properties of lipids mean they require alternative transport mechanisms?

A

Lipids are not very soluble

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23
Q

What is the role of HDL and LDL?

A

HDL removes excess cholesterol from the body by transporting it to the liver
LDL is involved in the process of fat build up in vasculature

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24
Q

What is the role of VLDL and where is it formed?

A

Transports triglycerides to adipose tissue for storage and energy.
It is formed in the liver.

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25
Where in the body are chylomicrons formed?
Formed in interstitial cells
26
What is meant by haemeostasis?
The arrest of blood loss from a damaged vessel
27
Describe the process of haemostasis
Damage to a vessel exposes collagen and glycoprotein of the sub endothelial matrix PRIMARY HAEMOSTASIS: Local vasoconstriction occurs Platelets aggregate Platelets bind fibrinogen to form a soft plug SECONDARY HAEMOSTASIS; 1) Prothrombin - prothrombinase 2) Prothrombinase - thrombin (11a) 3) Thrombin cleaves fibrinogen to form fibrin (solid clot)
28
After birth the foramen ovale becomes covered up. What is the depressed region of the RA now referred to as?
The foramen ovalis
29
What promotes the release of endothelin? - a vasoconstrictor and bronchoconstrictor
Mechanical shearing force ADH Angiotensin II Hypoxia
30
What inhibits the release of endothelin?
Prostacyclin
31
From the right atrium working down the right border of the heart to the bottom then up the left side, name the limb leads used for the ECG then do the same for the chest leads
VR, III, VF, II, I, VL V1, V2, V3, V4, V5, V6
32
How do you work out the heart rate from an ECG if the rate is regular? How do you do it if the rate is irregular?
300 divided by the number of large boxes between R-R intervals Number of QRS complexes in 30 large squares multiplied by 10
33
What causes RV axis deviation?
RV hypertrophy
34
What causes LV axis deviation?
LV hypertrophy
35
What is meant by depolarisation?
The electrical change which causes the inside of a cell to become less negative - this causes an upstroke in the action potential
36
What is meant by repolarisation?
The electrical change which causes the membrane potential to return to a negative value - this causes the downstroke return to normal in an action potential
37
In a SA node cell, describe the 3 main stages in the action potential
1 - K+ and Na+ influx (funny current) and transient Ca2+ influx 2 - Ca 2+ influx through L-type channels 3- K+ efflux
38
In a cardiac myocyte, describe the 4 stages in the action potential
``` 0 - Na+ influx 1 - Transient K+ efflux 2 - Ca2+ influx through L-type channels 3 - K+ efflux 4 - Return to the resting membrane potential ```
39
What is meant by preload?
The degree of stretch at the start of systole - Relates to EDV and the volume of blood in the ventricles at the end of diastole which determines the venous return to the heart
40
What is meant by afterload?
Ventricular pressure at the end of systole
41
What is Frank Starling's Law?
The more the ventricles are filled with blood (thus the greater the EDV), the greater the systolic contractions (SV)
42
Diastole refers to which stage of the cardiac cycle? What are the valves like in this stage?
Passive filling = DIASTOLE | - the AV valves are open to allow blood to flow into the heart
43
Atrial systole refers to which stage of the cardiac cycle? What are the valves like in this stage?
Active filling = ATRIAL SYSTOLE - The atria contract and the ventricles relax - The AV valves are open
44
What occurs in ventricular systole? Describe the changes with reference to the heart valves
Isovolumetric ventricular contraction is followed by isovolumetric ventricular ejection The AV valves close, SL valves open, then SL valves close
45
Which neurotransmitter is involved in sympathetic control of the heart and which receptors does it act on?
Noradrenaline acts on B1 adrenoceptors
46
Which neurotransmitter is involved in parasympathetic control of the heart and which receptors does it act on?
Acetylcholine acts on M2 receptors
47
Which heart sound coincides with the carotid pulse?
S1 (lub)
48
When do the heart sounds occur?
S1 (LUB) - at the start of systole when the SL valves close and the AV valves open S2 (DUB) - at the start of diastole when the AV valves close and the SL valves open
49
What equation does MABP = ?
MABP = diastole + 1/3 (systolic - diastolic)
50
A Pressure Gradient between the Aorta (AO) | and the Right Atrium (RA) drives the blood around the systemic circulation - how is this pressure gradient worked out?
Pressure gradient = Mean Arterial Pressure (MAP) – Central Venous (right atrial) Pressure (CVP)
51
What is resistance of blood flow inversely proportional to?
Resistance to blood flow is inversely proportional to the radius of a blood vessel to the power of 4
52
What causes a third heart sound (S3)?
Due to turbulent blood flow during passive filing of the ventricles
53
What causes a fourth heart sound (S4)?
Turbulent blood flow from atrial contraction into a less compliant ventricle during active filling
54
How do vagal manoeuvres increase parasympathetic output?
By activating baroreceptors - this slows HR and suppresses conduction through the AV node. Can be used for AF / atrial tachycardia/ flutter
55
Which baroreceptors are activated by the valsava manoeuvre and the which are activated by massaging the bifurcation of the carotid artery?
Valsava manoeuvre - aortic baroreceptors (CN X signals to the medulla) Massaging the bifurcation of the carotid artery - baroreceptors in the carotid sinus (CN IX signals to the medulla)
56
How does calcium cause contractions?
Calcium binds to troponin causing a conformational change which moves the protein away and frees the binding site to allow for interaction between actin and myosin
57
Where is calcium stored and explain its release
Calcium is stored in the sarcoplasmic reticulum. Its release is dependent on the influx of extracellular calcium ( calcium induced calcium release CICR)
58
What effect does calcium have in the SA node action potential and the myocyte action potential?
In the SA node cell, influx of calcium causes the upstroke (depolarisation) In a myocyte cells, influx of calcium causes the downstroke (2) (repolarisation)
59
What is the role of the RAAS system.. what does RAAS stand for?
RAAS (renin angiotensin aldosterone system) | - Regulates plasma volume, TPR and therefore MAP
60
Which enzyme is responsible for the conversion of angiotensin 1 to angiontensin II?
ACE (angiotensin converting enzyme)
61
What effect does angiotensin II have?
Causes the release of aldosterone from the adrenal cortex
62
What effects does aldosterone have?
Systemic vasoconstriction Increased TPR Increased sodium and water retention Increases plasma volume (BP)
63
What does the RAAS system cause the release of from the juxtaglomerular apparatus in the kidney?
Release of renin
64
What does contraction of vascular smooth muscle cause?
Vasoconstriction - increased TPR and MAP
65
What does relaxation of vascular smooth muscle cause?
Vasodilation - decreased TPR and MAP
66
Adrenaline has different effects on vascular depending on which receptors it acts on. Adrenaline acting on a-receptors in the skin, gut and kidneys has what effect? Adrenaline acting on B2 receptors in cardiac and skeletal muscle arterioles has what effect?
Adrenaline acting on a-receptors in the skin, gut and kidneys - VASOCONSTRICTION Adrenaline acting on B2 receptors in cardiac and skeletal muscle arterioles - VASODILATION
67
What effect do angiotensin II and antidiuretic hormone both have on vasculature?
VASOCONSTRICTION
68
What is resistance to blood flow directly proportional to?
Blood viscosity and the length go the blood vessel
69
Vascular smooth muscles are partially constricted at rest, what is this referred to as?
Vasomotor tone
70
What factors favour filtration at capillaries?
Cappillary hydrostatic pressure | Interstitial fluid osmotic pressure
71
What factors oppose filtration at capillaries?
Interstitial fluid hydrostatic pressure | Capillary osmotic pressure
72
Describe the baroreceptor response to decreased MAP
``` Increased sympathetic activity of the heart Increased TPR Increased SV Decreased vagal activity Arteriolar vasoconstriction ```
73
What effect does heat exposure have on muscle tone?
Heat exposure decreases muscle tone
74
What is the best measurement for determining total body fat?
Tricep skin-fold thickness

CARDIOVASCULAR (11 decks)

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