11.3 Kidney (HL)

Question 1

What is the excretory system in insects?

Answer 1

Malpighian tubules

Question 2

How do Malpighian tubules work?

Answer 2

Directly branches of the intestinal tract and uptakes nitrogenous waste which is combined later with digested food and excreted via the anus

Question 3

Describe the structure of the kidney

Answer 3

Oxygenated blood brought by the renal artery and deoxygenated removed via the renal vein
The ureter leads into the renal pelvis which branches into medulla surrounded by a cortex

Question 4

What molecule in the kidney filter blood?

Answer 4

Nephrons

Question 5

What do nephrons produce?

Answer 5

Urine

Question 6

How will blood in the renal vein differ from that in the renal artery?

Answer 6

Less urea
Less water and solutes
Less glucose and O2
More CO2

Question 7

Describe the components of a nephron

Answer 7

Bowman’s capsule
Proximal convoluted tubule
Loop of Henle
Distal convoluted tubule

Question 8

What is the function of the Bowman’s capsule (kidney)?

Answer 8

First part of the nephron where blood is initially filtered to form filtrate

Question 9

What is the function of the proximal convoluted tubule (kidney)?

Answer 9

Folded structure connected to the Bowman’s capsule where selective reabsorption occurs

Question 10

What is the function of the loop of Henle (kidney)?

Answer 10

Selectively permeable loop that descends into the medulla and establishes a salt gradient

Question 11

What is the function of the Distal convoluted tubule (kidney)?

Answer 11

Folded structure connected to the loop of Henle where further selective reabsorption occurs

Question 12

What are the functions of nephrons?

Answer 12

Ultrafiltration
Selective reabsorption
Osmoregularion

Question 13

Where in the nephron does ultrafiltration occur?

Answer 13

The glomerulus at the Bowman’s capsule

Question 14

Where in the nephron does selective reabsorption happen?

Answer 14

In the convuluted tubules (proximal and distal)

Question 15

Where in the nephron does osmoregulation happen?

Answer 15

In the loop of Henle a salt gradient draws water out of the collective duct

Question 16

Describe the glomerulus

Answer 16

A knot-like capillary tuft encapsulated by the Bowman’s capsule and comprised of surface cells called podocytes
Between the podocytes and glomerulus is a basement membrane which filters blood

Question 17

Describe the structure of podocytes

Answer 17

Cells with cellular extensions (pedicles) that wrap around the blood vessel of the glomerulus

Question 18

Describe the process of blood filtration in nephrons

Answer 18

Blood is filtered by a mesh called the basement membrane
The glomerular blood vessels are fenestrated to allow blood to flow freely

Question 19

How is the basement membrane selective?

Answer 19

It is size-selective

Question 20

What cannot be found in the filtrate of the nephron?

Answer 20

Blood cells, platelets and plasma proteins

Question 21

How does hydrostatic pressure aid in ultrafiltration?

Answer 21

Blood is forced at high pressure against the basement membrane

Question 22

How is high hydrostatic pressure achieved in the glomerulus?

Answer 22

Wider afferent arteriole that leads into a narrow efferent arteriole

Question 23

Describe selective reabsorption (kidney)

Answer 23

Reuptake of useful substances mostly in the proximal convoluted tubule

Question 24

What feature of the proximal convoluted tubules makes it good for reabsorption?

Answer 24

Microvilli with tight junctions and many mitochondria

Question 25

What is reabsorbed into the blood stream?

Answer 25

Glucose, amino acids, vitamins, hormones, (~80%) mineral ions and water

Question 26

How are mineral ions reabsorbed by the proximal convoluted tubule?

Answer 26

Actively via protein pumps

Question 27

How are vitamins reabsorbed by the proximal convoluted tubule?

Answer 27

Actively via carrier proteins

Question 28

How are glucose and amino acids reabsorbed by the proximal convoluted tubule?

Answer 28

Co-transported across the apical membrane with sodium

Question 29

How is water reabsorbed by the proximal convoluted tubule?

Answer 29

Follows the movement of mineral ions passively via osmosis

Question 30

Which two key features in the kidney are involved in osmoregulation?

Answer 30

Loop of Henle ADH

Question 31

Where is the salt gradient in the kidney?

Answer 31

In the medulla in the loop of Henle (nephrons)

Question 32

What is the descending limb of the loop of Henle permeable to?

Answer 32

Water but not salt

Question 33

What is the ascending limb of the loop of Henle permeable to?

Answer 33

Salt but not water

Question 34

How does the salt gradient change throughout the loop of Henle?

Answer 34

As the loop descends to the medulla it becomes more salty and hypertonic

Question 35

In which way does the vasa recta blood network flow and what does this cause?

Answer 35

In the opposite direction to the loop of Henle which means salts released from the ascending limb are drawn down into the medulla further establishing the gradient

Question 36

What effect does ADH have?

Answer 36

Increases water reabsorption by the kidney

Question 37

How does ADH increase water absorption?

Answer 37

It increases the permeability of the collecting duct to water and so less water remains in the filtrate

Question 38

What effect does dehydration have on blood pressure?

Answer 38

Decreases

Question 39

What effect does overhydration have on blood pressure?

Answer 39

Increases

Question 40

What urinary analysis could signal of disease?

Answer 40

Glucose (diabetes) Proteins (may indicate disease or hormonal conditions) Blood cells (variety of diseases including cancer) Drugs/ toxins (PEDs)

Question 41

Describe haemodialysis

Answer 41

Blood is removed and pumped through a dialyser which restricts the passage of certain molecules and produces fresh dialysis fluids and removes waste

Question 42

What is the best treatment for long-term kidney faliure?

Answer 42

Kidney transplant