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BRS Y1 > Week 8- Control of Heart Function > Flashcards

Week 8- Control of Heart Function Flashcards

1
Q

What is the medical term for increased heart rate?

A

Chronotrophy

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2
Q

What is the medical term for increased force of contraction?

A

Inotrophy

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3
Q

What nervous system affects the kidneys?

A

Sympathetic

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4
Q

What happens when theres reduced baroreceptor firing?

A

Increases sympathetic nerve activity

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5
Q

What happens when theres increased baroreceptor firing?

A

Reduced SNS activity

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6
Q

What makes up the arterial circuit

A

Aortic arch
Carotid sinus
Afferent arterioles of the kidneys

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7
Q

What receptors are associated with changes in sympathetic nervous system activity?

A

Baroreceptors

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8
Q

What 2 locations does parasympathetic stimulation arise from?

A

Cranial part of spinal chord

Sacral part of spinal chord

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9
Q

What 2 locations does sympathetic stimulation arise from?

A

Thoracic vertebra

Lumbar vertebra

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10
Q

What pre and post ganglionic neurotransmitters does the parasympathetic nervous system use?

A

Pre: Ach
Post: Ach

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11
Q

What pre and post ganglionic neurotransmitters does the sympathetic nervous system use?

A

Pre: Ach
Post: NA

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12
Q

In controlling the heart function, what role does the parasympathetic nervous system play?

A

Controlling the heart rate

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13
Q

In controlling the heart function, what role does the sympathetic nervous system play?

A

Controlling circulation

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14
Q

What receptors does the sympathetic nervous system activate?

A

Beta 1

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15
Q

What does the activation of beta 1 receptors in the heart do?

A

Activates cyclic AMP which increases heart rate

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16
Q

Where does nervous stimulation go to in the heart?

A

SAN

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17
Q

Under tonic (restful) conditions which branch of the nervous system is more active?

A

Parasympathetic

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18
Q

How do sympathetic nerves increase blood volume in the kidney?

A

They decrease glomerular filtration, decreasing sodium secretion increasing blood vol

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19
Q

In the renal system what do sympathetic nerve fibers innervate?

A

Afferent and efferent arterioles of the glomerulus

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20
Q

What is the primary sight of sympathetic activity in the kidneys?

A

Afferent arterioles

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21
Q

What receptors do sympathetic nerves act on in the kidneys? What effect does this have?

A

Alpha 1 receptors, causes vasoconstriction, reduces glomerular filtration rate and reduces sodium filtered

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22
Q

What cells are the site of synthesis, storage and release of renin?

A

Juxtaglomerular cells

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23
Q

What receptor allows renin secretion?

A

Beta 1 adrenoreceptor

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24
Q

What local mediators cause vasodilation?

A

Nitric oxide

Prostacyclin

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25
Q

What local mediators cause vasoconstriction?

A

Thromboxane A2

Endothelins

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26
Q

What systemic mediators cause vasoconstriction?

A

Vasopressin
Noradrenaline/adrenaline
Angiotensin II

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27
Q

What systemic mediators cause vasodilation?

A

Kinin

Atrial natriuretic peptide (ANPs)

28
Q

What 4 factors affect venous pressure?

A

Blood vol
SNS activation of veins
Skeletal muscle pumping
Respiratory movement

29
Q

What affects atrial pressure?

A

Venous return

30
Q

What effects venous return?

A

Venous pressure

31
Q

Whats the main pacemaker of the heart?

A

SAN

32
Q

What is the nerve involved with the parasympathetic control of the heart?

A

Vagus

33
Q

What does the parasympathetic nervous system do to the heart? What phase does it specifically affect and how?

A

Slows down the heart rate and decreases the slope of phase 4

34
Q

What does the sympathetic nervous system do to the heart? What phase does it specifically affect and how?

A

Increases the heart rate and increases the slope of phase 4

35
Q

What receptors detect blood volume?

A

Venous volume receptors

36
Q

How do venous volume receptors increase blood pressure?

A

They increases renin secretion, which increases angiotensin II production, leading to vasoconstriction and increased blood pressure

37
Q

What sensors are present in the cardiopulmonary circuit?

A

Volume sensors

38
Q

What sensors are present in the arterial circuit?

A

Pressure sensors

39
Q

Where is the vasomotor centre located?

A

Bilaterally in the reticular substance of the medulla and lower third of the pons

40
Q

What comprises the vasomotor centre?

A 
Vasoconstrictor area (pressor)
Vasodilator area (depressor)
Cardio-regulatory inhibitory area
41
Q

What does the lateral portion of the VMC do to heart activity?

A

Influences heart rate and contractility

42
Q

What does the medial portion of the VMC do to heart activity?

A

Signals via vagus nerve to decrease heart rate

43
Q

How is the VMC influenced?

A

By higher centres in the brain which have excitatory or inhibitory effects on it

44
Q

How does the VMC transmit impulses and to where?

A

Distally through the spinal chord to almost all blood vessels

45
Q

How is blood pressure detected in the kidneys?

A

By arterial baroreceptors

46
Q

What is venous volume distribution affected by?

A

Peripheral venous tone, gravity, skeletal muscle pump and breathing

47
Q

What determines the amount of blood flowing back to the heart?

A

Central venous pressure (mean pressure in the right atrium)

48
Q

How does venous constriction affect compliance and venous return?

A

Decreases compliance

Reduces venous return

49
Q

In arterioles what does constriction determine?

A

Bloodflow to downstream organs
Mean arterial blood pressure
The pattern of blood flow to organs

50
Q

How do local and systemic mechanisms of regulating blood flow differ in terms of their relation to smooth muscle?

A

Local mechanisms are intrinsic to smooth muscle

Systemic mechanisms are extrinsic to smooth muscle

51
Q

How do local and systemic mechanisms of regulating blood flow differ in terms of their mediators?

A

Local mechanisms use endothelium derived mediators

Systemic mechanisms use non endothelium derived mediators

52
Q

What are local mechanisms important for in the regulation of blood flow?

A

Reflex local blood flow regulation

53
Q

Describe action potentials of the AVN

A

They are slow and calcium mediated

54
Q

What is found at the base of the right atrium?

A

Triangle of Koch

55
Q

How long is the cardiac action potential compared to normal action potentials?

A

200-300 ms compared to the usual 2-3ms

56
Q

What are the 5 phases of the cardiac action potential?

A 
Phase 0: upstroke
Phase 1: early repolarisation
Phase 2: plateau
Phase 3: repolarisation
Phase 4: resting membrane potential
57
Q

What is the absolute refractory period?

A

The time period where no action potential can be initiated

58
Q

What is the relative refractory period?

A

The time period where an action potential can be generated but only with strong stimulus

59
Q

What is the resting membrane potential determined by?

A

K+ efflux

60
Q

What is the upstroke determined by?

A

A large increase in the membrane permeability to sodium

61
Q

Why do different parts of the heart have different action potential shapes?

A

They have different ion currents flowing and different ion channel expression

62
Q

What phases are missed out of the SAN action potential?

A

Phase 1 and 2 (early repolarisation and plateau)

63
Q

What type of calcium channels does the SAN have?

A

T type (T= transient aka faster)

64
Q

What does the L in L type channels stand for?

A

Latent (slow)

65
Q

What is the funny current of the SAN?

A

Flow of sodium current that causes phase 4

66
Q

What activates phase 4 of the SAN?

A

Cyclic AMP

BRS Y1 (52 decks)

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