Physiology part 3 Flashcards

1
Q

Define blood pressure?

A

the outwards (hydrostatic) pressure exerted by the blood on blood vessel walls

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2
Q

Define systemic systolic arterial blood pressure?

A

pressure exerted by the blood on the walls of the aorta and systemic arteries when the heart contracts

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3
Q

Define systemic diastolic arterial blood pressure?

A

pressure exerted by the blood on the walls of the aorta and systemic arteries when the heart relaxes

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4
Q

Define hypertension?

A

Clinic blood pressure of 140/90 mmHg or higher and day time average of 135/85 mmHg or higher

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5
Q

Define pulse pressure?

A

Is the difference between systolic and diastolic blood pressures

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6
Q

What is the normal range of pulse pressure?

A

30 and 50 mmHg

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7
Q

What is MAP?

A

the average arterial blood pressure during a single cardiac cycle, which involves contraction and relaxation of the heart

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8
Q

Why is MAP not the average of systolic and diastolic?

A

Diastolic portion of the cardiac cycle is about twice as long as the Systolic portion of the cardiac cycle

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9
Q

How is MAP calculated?

A

[(2x Diastolic) + Systolic] divided by 3

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10
Q

What is the normal range of MAP?

A

70-105mmHg

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11
Q

What MAP is required to perfuse the brain, heart and kidneys?

A

60mmHg

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12
Q

What is the sensor for negative feedback MAP system?

A

Baroreceptors

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13
Q

What is the control centre for negative feedback MAP system?

A

Medulla

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14
Q

What is the effector for negative feedback MAP system?

A

Heart and blood vessels

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15
Q

What is the response of the heart to change in MAP?

A

Change in HR, SV

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16
Q

What is the response of the blood vessels to change in MAP?

A

Varying systemic vascular resistance

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17
Q

Where are the baroreceptors?

A

Carotid sinus

Aortic

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18
Q

How do the baroreceptor signals reach the medulla?

A

Carotid- IXth CN

Aortic Xth CN

19
Q

Define baroreceptors?

A

Mechanoreceptors sensitive to stretch

20
Q

What happens to firing rate in baroreceptor afferent neurones in response to increased MAP?

21
Q

What happens to firing rate in baroreceptor afferent neurones in response to decreased MAP?

22
Q

What is the nucleus tractus solitairius?

A

Site of 1st synapse for all CVS afferents in the medulla

23
Q

What does the medulla do?

A
  1. receives CVS afferent information
  2. Relays information to other regions in the brain e.g. medulla, hypothalamus, cerebellum
  3. Generates vagal (parasympathetic) outflow to the heart- relay to the nucleus ambiguus in the medulla
  4. regulates spinal sympathetic neurones
24
Q

What is systemic vascular resistance?

A

Sum of resistance of all vasculature in the systemic circulation

25
How can MAP be regulated?
HR SV SVR
26
Define | autorhythmicity
Hearts ability to beat in the absence of external stimuli
27
What is the role of the sympathetic division in HR?
Accelerates HR
28
What is the role of the parasympathetic division in HR?
stimulation of the vagus nerve (10th cranial nerve) slows the heart rate (bradycardia)
29
What acts on B1 receptors?
Noradrenaline
30
What acts on muscarinic receptors?
Acetylcholine
31
When does SV increase?
If the contractile strength of the heart is increased
32
What regulates the SV?
ANS
33
What nerves innervate the myocardium?
Sympathetic nerves
34
What is the intrinsic control of SV?
Frank-Starling Mechanism or the Starling’s Law of the Heart
35
What are the Major Resistance Vessels?
Arterioles
36
What regulates SVR?
vascular smooth muscles
37
What does contraction of vascular smooth muscle cause?
vasoconstriction and increases SVR and MAP (i.e. pressure upstream)
38
What does relaxation of vascular smooth muscle cause?
vasodilatation and decreases SVR and MAP
39
What supplies VSM and what is the neurotransmitter?
SYMPATHETIC nerve fibers. The neurotransmitter is NORADRENALINE acting on alpha receptors
40
Define vasomotor tone?
Vascular smooth muscles are partially constricted at rest.
41
What causes vasomotor tone?
tonic discharge of sympathetic nerves resulting in continuous release of noradrenaline
42
What increases vasomotor tone?
Increased sympathetic discharge will increase the vasomotor tone
43
When does baroreceptor firing decrease?
if high arterial blood pressure is sustained