Week 11 The Renal system

Question 1

Urinary system consists of:

Answer 1

Kidneys
Ureters
Bladder
Urethra

Question 2

Kidney consists of:

Answer 2

Capsule
Cortex
Medulla
Hilum
Pelvis
Lots of blood vessels

Question 3

The Urinary system

Answer 3

Anatomy:
– Kidneys: contain nephrons (microscopic filters)
– Ureters: tubes from kidneys to bladder.
– Bladder: urine storage tank.
– Urethra: tube by which urine leaves body.

• Physiology:
– Conservation of water/salts
– Some glucose supply – used during prolonged fasting.
– Excretion of wastes (creatinine, urea etc.)
– Hormone production – erythropoietin (stim. RBC production)
– Enzyme production – renin (regulates blood pressure)
– Vitamin activation - Vitamin D3

Question 4

The internal structure of a kidney

Answer 4

Outer Cortex:
– site of filtration
– light-coloured, granular appearance

• Inner Medulla:
– site of re-absorption/excretion
– dark, reddish-brown colour
– arranged into series of “pyramids”.
– point of each pyramid = the papilla
– papilla points inwards, towards
calyces

• Pelvis:
– funnel shaped tube
– calyces collect urine
– walls contain smooth muscles

Question 5

The Nephron

Answer 5

Renal Corpuscle
• Capillaries (Glomerulus)
• Cup-shaped hollow
structure (Glomerular
capsule)

Renal Tubule
• Proximal convoluted
tubule
• Nephron loop
• Distal convoluted tubule

Question 6

Renal Corpuscle

Answer 6

Glomerulus
– Endothelium of glomerular
capillaries is fenestrated
(has pores).
– Fluid passes from blood to
glomerular capsule

Glomerular (Bowman’s)
Capsule
– Parietal layer contributes to
structure.
– Visceral layer has branching epithelial cells called podocytes
(foot cells).
– Podocytes terminate in foot processes which have openings
called filtration slits.
– Filtrate enters through the filtration slits.

Question 7

Urine Formation (Check slide for diagram and more detail)

Answer 7

Glomerular filtration
•Produces a cell and
protein free filtrate

Tubular reabsorption
•Reclaims that which the
body needs to keep

Tubular secretion
•Adding to the waste
container

Question 8

Antidiuretic hormone (ADH)

Answer 8

Released by posterior
pituitary gland
2. Regulates water permeability
within the collecting ducts
3. Water re-absorbed into the
blood
4. Urine becomes more
concentrated

Question 9

Aldosterone

Answer 9

1. Released by adrenal glands(mineralocorticoid)
2. Enhances Na+ reabsorption in distal convoluted tubules
   and collecting ducts
3. Water follows Na+ ions back into the blood (↑ in BP)
4. Na+ reabsorption is coupled to K+ secretion into the urine
5. Urine becomes more concentrated

Question 10

Tubular Secretion

Answer 10

Occurs:
– proximal convoluted tubule (MAIN SITE)
– collecting duct
Tubular Secretion

Importance:
– disposal of certain substances
• e.g. drugs - penicillin
– controlling blood pH
– ridding body of excess potassium (K+)
– ridding body of undesirable/toxic end-products
• e.g. urea, uric acid (wastes from protein metabolism)

Question 11

Ureters

Answer 11

Continuation of the
renal pelvis
• Convey urine from the
kidneys to the bladder
• Two muscle sheets
• Internal longitudinal layer
• External circular layer
• External surface is fibrous connective
tissue