Lecture 2: Blood pressure Flashcards

1
Q

What is a portal system?

A

When a capillary bed reassembles into a blood vessel that splits again into another capillary bed

Allows transport of chemicals from one tissue to another without being diluted by mixing with blood at the heart

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2
Q

What is the equation for mean pulse pressure?

A

Pmean = Pdiastolic + (Psystolic-Pdiastolic / 3)

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3
Q

What is normal SV?

A

70ml

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4
Q

What is normal HR?

A

70bpm

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5
Q

What is normal RR interval?

A

0.86s

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6
Q

What is normal CO?

A

4.9L/min

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7
Q

What is normal EDV?

A

120ml

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8
Q

What is normal ESV?

A

50ml

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9
Q

What is normal EF?

A

58% (55-70)

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10
Q

What is the effect of radius on flow?

A

Flow increases to the power of 4

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11
Q

What are the causes of dilation and constriction of individual blood vessels?

A

Central: CNS, autonomic, endocrine

Local: blood vessels have own control

Immune: flow of immune cells

Haemostasis

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12
Q

What controls systemic blood pressure?

A

Local: endothelial cells, NO

Neurological: SNS

Humoral: renal, pituitary, adrenal

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13
Q

What are the effects of increased SNS on blood vessels?

A

Increased PR, increased pressure, increased HR, increased CO

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14
Q

Where are baroreceptors located?

A

Transverse aortic arch and carotid sinuses of the left and right carotid arteries

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15
Q

Where are chemoreceptors located?

A

Carotid bodies and aortic bodies

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16
Q

What is volume overload?

A

When preload is too large and the heart is no longer able to respond appropriately

17
Q

What factors increase preload?

A

Increased ventricular compliance

Increased atrial contractility

Decreased HR

Increased aortic pressure

Increased venous pressure (Increased blood volume and/or decreased venous compliance)

18
Q

What causes increased after load?

A

Increased back pressure from aorta or pulmonary arteries

If the exit valve fails to open completely

19
Q

What causes pressure overload?

A

When the after load is elevated

20
Q

Describe the thoracic pump.

A

During inspiration, intrathoracic pressure is negative, abdominal pressure is positive (compression of the abdominal organs by diaphragm), creates pressure gradient that pulls blood to right atrium

21
Q

Describe muscle pump.

A

Contraction of limb muscles, squeezes blood out of nearby veins, valves assure one way flow to heart

22
Q

When does most blood flow occur?

A

Diastole

23
Q

What conditions result fro hypertension?

A
Aneurysm
Stroke
MI
Kidney failure
Heart failure 
Cardiac hypertrophy
24
Q

What is orthostatic hypertension?

A

Low BP on standing
(decreased venous return)

Dizziness/syncope

Causes: drugs, hypovolaemia, age