Circulatory physiology and specialist circulations

Question 1

Where is the cardivascular centre?

Answer 1

Located in the medulla oblongata; integrates input from baroreceptors, chemoreceptors, and stretch receptors to regulate cardiac output and vascular tone.

Question 2

What is baroreceptor reflex?

Answer 2

Stretch receptors in carotid sinus/aortic arch detect pressure changes.
High BP: Increases parasympathetic output, decreases HR.
Low BP: Increases sympathetic output, raises HR and vasoconstriction.

Question 3

What is the orthostatic reflex?

Answer 3

Sudden standing → blood pools in legs → baroreceptor reflex restores BP.

Question 4

what are atrial and pulmonary stretch receptors?

Answer 4

Respond to increased blood volume → reduce sympathetic tone, enhance diuresis.

Question 5

What do chemoreceptor reflexes do?

Answer 5

Detect blood pH, O₂, and CO₂ levels; adjust respiratory and cardiovascular output.

Question 6

What is the hormonal regulation of blood pressure ?

Answer 6

Renin-Angiotensin-Aldosterone System (RAAS): Increases BP via vasoconstriction and fluid retention.
ADH: Promotes water retention, increasing blood volume.
ANP: Reduces BP by promoting vasodilation and diuresis.

Question 7

what appens to organ blood flow ar rest and exercise?

Answer 7

Rest: Prioritises vital organs (e.g., brain, kidneys).
Exercise: Increases flow to skeletal muscles; reduced flow to non-essential organs (e.g., GI tract).

Question 8

What is coronary circulation?(during exercise)

Answer 8

Supplies oxygen to heart muscle.
Specialised Function: High oxygen demand, flow peaks during diastole.
Vulnerability: Pathological interruptions (e.g., atherosclerosis) cause ischaemia.

Question 9

What is skeletal muscle circulation during exerise?

Answer 9

Vasodilation increases blood flow.
Skeletal Muscle Pump: Muscle contractions compress veins, aiding venous return and heart filling.

Question 10

describe cerebral circulation?

Answer 10

High perfusion priority, tightly regulated.
Local Mechanisms:
Autoregulation: Maintains constant flow despite BP changes.
Metabolic Control: CO₂ and pH influence vasodilation.

Question 11

describe cutaneous circulation

Answer 11

Regulates body temperature via blood flow adjustments.
Vasodilation: Heat dissipation.
Vasoconstriction: Conserves heat.

Question 12

describe capillary exchange and lymphatics

Answer 12

Exchange driven by hydrostatic and oncotic pressures.
Lymphatic system returns interstitial fluid to circulation.

Question 13

What are oedema causes?

Answer 13

Increased capillary hydrostatic pressure, reduced oncotic pressure, or lymphatic obstruction.