2.6 KIDNEYS AND HOMOSTATIS

Question 1

WHAT ARE THE FUNCTIONS OF THE KIDNEY?

Answer 1

1. regulate water content of the blood
2. remove waste products from the blood.

Question 2

DESCRIBE THE PATHWAY TAKEN BY SUBSTANCES THROUGH THE EXCRETORY SYSTEM

Answer 2

Renal artery -> Kidney -> Renal vein (blood) -> Ureter (water, sugar and salt) -> Bladder -> Urethra

Question 3

DESCRIBE THE STRUCTURE OF THE KIDNEY

Answer 3

Within is the nephron, medulla, cortex, pelvis and ureter

Question 4

EXPLAIN WHERE URINE IS MADE

Answer 4

The nephron consists of a cup-shaped Bowman’s capsule and a capillary knot, which are connected by the renal artery. The rest of the nephron consists of a coiled tubule, leading to a loop shape, and collecting duct, which then pass to the bladder and renal vein.

Question 5

WHAT IS THE PROCESS OF ULTRAFILTRATION?

Answer 5

The arteriole in the blood vessels creates a high pressure, forcing small molecules like water, salts, urea and glucose out of the capillary and into the Bowmans capsule.

Question 6

WHAT IS THE PROCESS OF SELECTIVE REABSORPTION?

Answer 6

The filtrate, a solution of glucose, salts and urea is reabsorbed into blood through selective reabsorption. The remaining fluid, urine, is collected and stored in the bladder.

Question 7

HOW DO THE KIDEYS REGULATE WATER CONTENT IN BLOOD?

Answer 7

By producing dilute urine if there’s too much water in blood or concentrated urine if there isn’t enough.

Question 8

WHAT IS ADH?

Answer 8

A hormone that allows the brain to monitor blood water concentration.

Question 9

HOW DOES ADH WORK?

Answer 9

• Decreases water = increased secretion of ADH so kidney absorbs more water
• Increased water = decreased secretion of ADH so kidney absorbs less water

Question 10

WHAT ARE THE REASONS FOR KIDNEY FAILURE?

Answer 10

• Infection
• A bad case of poisoning
• An injury with severe loss of blood
• Very high blood pressure

Question 11

WHAT IS KIDNEY DIALYSIS?

Answer 11

Kidney dialysis uses a machine to replicate kidney functions, pumping blood through thin, selectively permeable membrane tubes. The machine maintains blood glucose levels and salt balance by containing the correct glucose and water concentrations. Dialysis is performed at frequent intervals, typically for individuals with kidney disease.

Question 12

WHAT IS A KIDNEY TRANSPLANT?

Answer 12

Kidney transplants are a long-term solution for kidney failure, requiring careful matching and tissue typing. Patients take immunosuppressant drugs to reduce rejection risk, but are more susceptible to infectious diseases. Long-term costs are cheaper than dialysis.

Question 13

WHAT ARE THE ETHICAL ISSUES OF A KIDNEY TRANSPLANT?

Answer 13

• Kidneys for transplants primarily come from sudden deaths from road accidents, strokes, and heart attacks.
• There is a shortage of kidney donors due to lack of registration.
• Wales’ ‘deemed consent’ legislation allows individuals without registration to donate without objection.
• Kidney dialysis is a common issue, with many people never receiving a transplant.
• In developing countries, kidneys are sold to fund food, medicine, or education.
• UK kidney transplants improve quality of life and save NHS money annually.