The Renal System

Question 1

What is the functions of the kidneys?

Answer 1

• Fluid balance
• Electrolyte balance
• Acid base balance
• Excretion of waste products
• Regulation of blood pressure
• Maintenance of calcium

Question 2

What is the nephron often referred to as?

Answer 2

The functional unit of the kidneys.

Question 3

What happens in the nephron?

Answer 3

Blood is filtered and urine is formed.
There are 3 processes involved:
- Filtration (occurs in the bowman’s capsule)
- Selective reabsorption (PCT)
- Secretion (secreted into tubules by peritubular capillaries)

Question 4

What are the 4 hormones impacting blood pressure?

Answer 4

• Renin angiotensin
• Aldosterone
• Antidiuretic Hormone (ADH)
• Atrial Natriuretic Peptide (ANP)

Question 5

What is Aldosterone?

Answer 5

Aldosterone is a hormone that increases the reabsorption of sodium and water, and the excretion of potassium.

Question 6

Where is Aldosterone secreted?

Answer 6

The adrenal cortex (outside of the adrenal gland, on top of the kidneys).

Question 7

How does Aldosterone increase blood pressure?

Answer 7

It increases the reabsorption from the tubules and back into the blood therefore, increasing blood pressure.

Question 8

What is Atrial Natriuretic Peptide (ANP)?

Answer 8

ANP is a hormone secreted by the atria of the heart in response to stretching of the atrial wall when blood volume is increased (recognised by baroreceptors).

Question 9

What does ANP decrease?

Answer 9

ANP decreases the reabsorption of sodium and water out of the proximal convoluted tubules and collecting ducts to promote excretion.

Question 10

What does Atrial Natriuretic Peptide ultimately do?

Answer 10

It increasers urinary volume and decreases blood volume. Which ultimately reduces blood pressure.

Question 11

What is Atrial Natriuretic Peptides “job”?

Answer 11

To reduce blood pressure.

Question 12

What is Antidiuretic Hormone (ADH)?

Answer 12

ADH is a hormone which is secreted by the posterior pituitary.

Question 13

What are the main roles of the Antidiuretic Hormone (ADH)?

Answer 13

• To increase blood pressure by reabsorbing water from the nephron back into blood rather than in urine.
• Contributes to negative feedback to maintain blood pressure.
• It increases water reabsorption.

Question 14

What is diabetes insipidus?

Answer 14

Diabetes insipidus is a rare condition where there is a hypo-secretion of ADH.

Question 15

What occurs in diabetes insipidus?

Answer 15

• Water reabsorption is impaired leading to excessive polyurisis. (Often more than 10 litres a day).
• Life threatening dehydration occurs.

Question 16

Is diabetes insipidus a primary or secondary cause?

Answer 16

Secondary cause of the hypothalamus.

Question 17

What does RAAS stand for?

Answer 17

Renin Angiotensin Aldosterone Systen (RAAS).

Question 18

What is Aldosterone’s effect on blood pressure?

Answer 18

Increases blood pressure.

Question 19

What is Atrial Natriuretic Peptide (ANP) effect on blood pressure?

Answer 19

Decreases blood pressure.

Question 20

What is Antidiuretic Hormone (ADH) effect on blood pressure?

Answer 20

Increases blood pressure.

Question 21

What is Renin Angiotensin effect on blood pressure?

Answer 21

Increases blood pressure.

Question 22

What is Aldosterone’s role?

Answer 22

• Increases the reabsorption of sodium and water.
• Excretion of potassium.

Question 23

What is Atrial Natriuretic Peptide (ANP) role?

Answer 23

• Decreases the reabsorption of sodium and water from PCT and collecting ducts.
• Increases water absorption.

Question 24

What is Antidiuretic Hormone (ADH) role?

Answer 24

• Increases the permeability of DCT and collecting ducts.
• Increases water absorption.

Question 25

What is Renin Angiotensin Role?

Answer 25

• Long term blood pressure control.
• Process of RAAS kicks in.

Question 26

Explain the process of RAAS?

Answer 26

• When there is a drop in blood pressure Renin is released into the blood.
• Renin converts plasma protein Angiotensinogen into Angiotensinogen 1. This happens in the liver.
• Angiotensinogen 1 is converted into Angiotensinogen 2 by the Angiotensin Converting Enzyme (ACE). This is produced in the lungs and in the kidneys.
• Angiotensin 2 is a hormone, which stimulates vasoconstriction of systemic arterioles.
• Angiotensin 2 stimulates the adrenal cortex to secrete aldosterone.
• This promotes the reabsorption of sodium in PCT; it acts on the nervous system to:
• Increase thirst via the hypothalamus.
• Release ADH in posterior pituitary (water retention).
• Reduces baroreflex sensitivity so it cannot counteract the RAAS effect.
• All of this helps to increase blood pressure.

Question 27

What are the 5 different types of Renal Replacement Therapy?

Answer 27

• Continuous Renal Replacement Therapy (CRRT).
• Continuous Veno-venous Haemofiltration (CVVH).
• Continuous Veno-venous Haemodialysis (CVVHD).
• Continuous Veno-venous HaemoDiaFiltration (CVVHDF).
• Slow continuous Ultrafiltration.