T3 L2 Intro to kidney & renal function

Question 1

What are the 2 functions of the urinary system?

Answer 1

Excretion - removal of organic waste products from body fluids
Elimination - discharge of waste products in the environment

Question 2

What are the 3 essential renal functions?

Answer 2

Excretion of endogenous waste products, drugs & their metabolites
Homeostasis - water & electrolyte balance, acid-base balance
Regulation - production of hormones such as erythropoietin and renin

Question 3

What is renal dysfunction?

Answer 3

Reduction in renal excretory function
Inability to maintain salt & water balance & acid-base balance
Compromised hormone function - anaemia, hypertension

Question 4

What happens if renal failure is severe & untreated?

Answer 4

Can lead to death

Question 5

What happens if renal failure is rapid?

Answer 5

Acute kidney injury
10% of renal failure
If you remove the problem the kidneys tend to recover

Question 6

What happens if renal failure develops over months/years?

Answer 6

Chronic kidney disease

90% of renal failure

Question 7

Where are the kidneys situated?

Answer 7

Posterior wall of abdomen
Behind peritoneum
On either side of vertebral column

Joined at medial side to renal artery, vein, nerves & ureter

Question 8

What is the size of a kidney?

Answer 8

120-170g in adults

11cm x 6cm x 3cm

Question 9

What is the cortex?

Answer 9

Outer layer

Composed of around 1.25million nephrons

Question 10

What is the medulla?

Answer 10

Inner layer

Has pyramids which drain into pelvis which drains to ureter

Question 11

What is the nephron?

Answer 11

Basic functional unit of the kidney responsible for urine formation & composition

Question 12

How many nephrons per kidney?

Answer 12

1.25million

Number & renal function declines with age

Question 13

What are the 5 distinct sections of the nephron?

Answer 13

Glomerulus
Proximal tubule
Loop of Henle
Distal tubule
Collecting duct

Question 14

What are the 2 types of nephron?

Answer 14

Cortical nephron

Juxtamedullary nephron

Question 15

Describe the cortical nephron

Answer 15

70-80% of nephrons in the human kidney
Located in cortex
Short look of Henle into medulla

Question 16

Describe the juxtamedullary nephron

Answer 16

20-30% of all nephrons in human kidneys
Situated closer to medulla
Loop of Henle extends deep into renal pyamids

Question 17

What are the functions of the nephron?

Answer 17

Filtration of blood to produce a filtrate
Reabsorption of water, ions & organic nutrients from filtrate
Secretion of waste products into tubular fluid
Transcellular transport
Paracellular transport

Question 18

What is transcellular transport?

Answer 18

Movement through cells

Question 19

What is paracellular transport?

Answer 19

Movement between cells

Question 20

How are the cells in the cortex adapted to provide energy for reabsorption & filtration?

Answer 20

Full of mitochondria

Question 21

Describe the pathway of blood flow from the renal artery to the nephrons

Answer 21

Renal artery –> segmental arteries –> interlobar arteries –> accurate arteries –> interlobular arteries –> afferent arterioles –> nephrons

Question 22

Describe the pathway of blood flow from the nephron to the renal vein

Answer 22

Nephrons –> venules –> interlobular veins –> arcurate veins –> interlobar veins –> renal vein

Question 23

What do the sympathetic postganglionic fibres from the sympathetic chain & fibres from coeliac ganglion supply?

Answer 23

The arteries
Afferent & efferent arterioles
Granular cells
Reduces blood supply to kidney during stress

Question 24

What does the parasympathetic supply from the vagus nerve supply?

Answer 24

May control tone of efferent arteries

May modify glomerular filtration rate & renal blood flow

Question 25

What is glomerular filtration?

Answer 25

Initial step in urine formation

All small molecules are filtered

Question 26

What small molecules are filtered in glomerular filtration?

Answer 26

Electrolytes
Amino acids
Glucose
Metabolic waste
Some drugs, metabolites

Question 27

What molecules remain in the blood after glomerular filtration?

Answer 27

Red blood cells
Lipids
Proteins
Most drugs, metabolites

Question 28

Describe tubular reabsorption

Answer 28

More than 99% of filtered water, electrolytes & nutrients are reabsorbed into the blood
Some solutes such as Na+ are reabsorbed down concentration and/or electrochemical gradient
Other molecules can undergo co-transport
Water follows passively along osmotic gradient created by solute reuptake via aquaporins
Reabsorption of solutes requires energy in form of ATP

Question 29

Describe tubular secretion

Answer 29

Some endogenous substances & drugs can’t be filtered a glomerulus
Specialised pumps in proximal tubule can transport compounds from plasma into nephron for excretin

Question 30

What are the 2 kinds of pumps used in tubular secretion?

Answer 30

Organic acids or drugs - uric acid, diuretics, antibiotics

Organic bases or drugs - creatinine, procainamide