CS: Blood Pressure Flashcards Preview

Year 2: Human Anatomy and Physiology > CS: Blood Pressure > Flashcards

Flashcards in CS: Blood Pressure Deck (27)
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1
Q

What is stroke volume?

A

Stroke volume is the volume of blood pumped from the left ventricle per beat

2
Q

How can stroke volume be increased?

A

Ventricles never fully empty following ventricle contraction, therefore, stroke volume can be increased by increased contraction by sympathetic (adrenergic) input or increased ventricular filling due to increased blood in ventricles prior to contraction.

The volume of blood that flows into the atria during atria diastole is known as the venous return. Increased venous returns will increase ventricular filling, and ultimately stroke volume, and greater ventricular filling will also increase ventricular muscle stretch.

3
Q

What is the venous return?

A

The volume of blood that flows into the atria during atria diastole

4
Q

What is Starlings law?

A

Increase in preload causes an increase in muscle fibre stretch, leading to increased force of ventricular contraction, resulting in a greater stroke volume. Decrease in preload causes a decrease in muscle fibre stretch, leading to decreased force of ventricular contraction, resulting in a reduced stroke volume.

5
Q

What are baroreceptors?

A

Pressure sensitive mechanoreceptors that respond to changes in arterial pressure and stretch

6
Q

Where are baroreceptors located?

A

Located in the aortic arch and the carotid sinus, and are connected to centres in the medulla oblongata by afferent neurons.

7
Q

How is blood pressure regulated by the medulla oblongata?

A

Cardiac feedback in response to information from baroreceptors via the sympathetic and parasympathetic afferent neurons of the ANS.

8
Q

What is the short-term regulation of rising blood pressure?

A
  1. Rising blood pressure
  2. Stretching of arterial walls
  3. Stimulation of baroreceptors in the carotid sinus and aortic arch
  4. Increased impulses to the medulla oblongata of the brain
  5. Increased activity of the vagus nerve (parasympathetic) and decreased activity of sympathetic cardiac nerves.
  6. Decreased cardiac output.
  7. Increased arterial diameter
  8. Lower blood pressure.
9
Q

What is the short-term response to falling blood pressure?

A
  1. Falling blood pressure
  2. Baroreceptors inhibited
  3. Decreased impulses to the medulla oblongata of the brain
  4. Decreased parasympathetic activity and increased sympathetic activity
  5. Blood vessels constrict
  6. Adrenal glands stimulated to release adrenaline and noradrenaline into the blood which causes an increase in heart rate, contractility and vasoconstriction.
  7. Increased blood pressure
10
Q

How is long-term regulation of blood pressure accomplished?

A

Long term regulation of blood pressure is primarily accomplished by altering blood volume. Long term regulatory processes promote the conservation of body fluid via renal mechanisms and stimulate intake of water to normalise blood volume and pressure.

11
Q

What incidents can cause a fall in blood pressure?

A

Loss of blood through haemorrhage, accident, or donation will lower the blood pressure and trigger processes to restore blood volume and pressure back to normal.

12
Q

Describe the renin-angiotensin pathway?

A

Juxtaglomerular cells, found in the afferent arterioles of the glomerulus of the kidneys, are specialised smooth muscle cells with b1 receptors that respond to (Nora)adrenaline. They release renin into the blood which binds to angiotensinogen and converts it to angiotensin I. Angiotensin I is converted to angiotensin II by angiotensin converting enzyme (ACE) in the lung capillaries.

13
Q

What cells release renin?

A

Juxtaglomerular Cells in the afferent arterioles of the glomerulus of the kidney nephrons

14
Q

What cells release ACE?

A

Lung capillary cells

15
Q

What is ACE?

A

Angiotensin Converting Enzyme

16
Q

What are the actions of angiotensin II?

A
  1. Potent vasoconstrictor that causes blood pressure to rise in the body’s arterioles.
  2. Stimulates release of aldosterone from the adrenal cortex that targets cells of the distal convoluted tubules.
17
Q

What is the role of aldosterone?

A

Promotes the retention of sodium ions and water, in exchange for potassium ions. Movement of sodium ions back into the blood creates an osmotic gradient which forces the reabsorption of water, from the urine, to increase blood volume.

18
Q

What is osmolarity?

A

Osmolarity is the total concentration of all solutes in a solution

19
Q

What causes dehydration?

A

Dehydration can be due to sweating, diarrhoea, or excessive urine flow

20
Q

What are the short-term effects of increased osmolarity?

A

Increased osmolarity excites the ‘thirst centres’ in the hypothalamus and triggers the individual to drink more water to rehydrate the blood and extracellular fluid; blood pressure and volume restored.

21
Q

What is the action of the hypothalamic thirst centres?

A

Send signals to the posterior pituitary gland to release ADH which stimulates the kidneys to reabsorb water through aquaporin water channels in the distal convoluted tubule and the collecting ducts.

22
Q

What is ADH?

A

Anti diuretic hormone

23
Q

What is the role of aquaporins?

A

Aquaporins aid in the movement of water from the urine to the bloodto decrease osmolarity and increase blood pressure and volume.

24
Q

What is the effect of caffeine and alcohol on ADH levels?

A

Decreased levels of ADH resulting in less water reabsorption and more dilute urine; excessive urination is seen.

25
Q

What happens when a RBC is placed in a isotonic solution?

A

Remains normal. No net flow of solutes.

26
Q

What happens when a RBC is placed in a hypertonic solution?

A

Water will leave the RBC and enter the hypertonic solution; will result in RBC crenation

27
Q

What happens when an RBC is placed in a hypotonic solution?

A

What will enter the RBC from the hypotonic solution; will cause RBC s to swell with water and eventually lyse.