2.1 Physiology continued

Question 1

How do the following effect stroke volume?

Hypercalceamia
Hypocalcemia
Ischaemia

Answer 1

Hyper- Shifts curve up and left
Hypo- Shifts curve down and right
Ischaemia- Shifts curve down and right

Question 2

What equation governs the work of the heart?

Answer 2

Cardiac output= Heart Rate x Stroke volume

Question 3

Describe the ultrastructure of the capillaries

Answer 3

Continous no clefts or channels (brain) // clefts only (muscle)
Fenestrated clefts and channels e.g. intestine
Discontinous- Clefts and massive channels e.g. liver

Question 4

What are the anti-clotting methods of the endothelium

Answer 4

There is no platelet aggregation
Produces prostacyclin and nitrous oxide
Produces tissue factor pathway inhibitor (TFPI)
Expresses thrombomodulin
Expresses heparin
Secretes tissue plasminogen activator (t-PA)

Question 5

What are the causes of oedema?

Answer 5

Lymphatic obstruction
Raised CVP
Hypoproteinemia
Increased capillary permeability

Question 6

Explain the extrinsic control of arterioles from the neural side.

Answer 6

Sympathetic nerves- Releases norepinerpherine
Binds to alpha 1 receptors
causes arteriolar constrition

Parasympathetic nerves- no effect

Question 7

Explain the extrinsic control of arterioles from the hormonal side?

(Epinephrine/Adrenaline)

Answer 7

Released from adrenal medulla
Binds to alpha 1 receptors
Causes arteriolar constriction

In skeletal and cardiac muscle it activates B2 receptors causing arteriolar dilation

Question 8

Explain the extrinsic control of arterioles from the hormonal side?

(Epinephrine/Adrenaline)

Answer 8

Produced in response to low blood volume
Causes arteriolar constriction
Therefore increased TPR

Question 9

Explain the extrinsic control of arterioles from the hormonal side?

(Vasopressin)

Answer 9

Released in response to low blood volume
Causes arteriolar constriction
Therefore an increase in TPR

Question 10

Explain the extrinsic control of arterioles from the hormonal side?

(Anti natriuretic peptide and brain natriuretic peptide)

Answer 10

Releases in response to low blood volumes
Causes arteriolar dilation
Therefore lowered TPR

Question 11

What is venous pressure?

Answer 11

5-20mmHg

Question 12

What factors contribute to pressure and flow in veins?

Answer 12

Gravity
Skeletal muscle pump
Respiratory pump
Venomotor tone
Systemic filling pressure

Question 13

What factors mediate the control of arterial pressure?

Answer 13

Nerves that enter the heart 
Central chemoreceptors 
Chemoreceptors in muscle
Jointreceptors
Higher centres

Question 14

Explain the valsalva manoeuvre

Answer 14

Thoracic pressure is transmitted trhough to the aorta
Increase in thoracic pressure, decreased MAP
Decreased MAP is detected and cardiac output increased
Thoracic pressure decreased
MAP is restored but reflex not worn off
Normality

Question 15

What three systems control long term blood pressure

Answer 15

Renin-agiotensin aldosterone system
Antidiuretic factor (ADH,vasopressin)
Atrial natriuretic peptide

They do this by lowering plasma volume

Question 16

Why is renin released

It eventually leads to the production of angiotensin II. What does it do?

Answer 16

In response to low MAP

Increased Na reabsorption
Reduces diuresis and increases plasma volume
Increases sense of thirst

Question 17

What causes a release of ADH?

Answer 17

Decrease in blood volume
Increase in osmolarity of interstitial fluid
Circulating angiotensin II

Question 18

What does ADH do?

Answer 18

Increases plasma volume
Causes vasoconstriction

(therefore increasing MAP)

Question 19

What hormones act to lower blood pressure?

Answer 19

Atrial natriuretic peptide-distention of atrium

BNP- distension of ventricles

Question 20

How do ANP and BNP lower blood pressure

Answer 20

Increased excretion of soidum
Inhibits renin release
Acts on medullary CV centres to reduce MAP