Urinary System

Question 1

Describe the location of the kidneys

Answer 1

Retroperitoneal, one on each side on posterior abdominal wall high up under diaphragm

Question 2

What protects the kidneys?

Answer 2

Encapsulation and protective layers of fascia and firm renal fat

Question 3

What is the renal cortex?

Answer 3

Outer region of the kidney

Question 4

What do renal pyramids do?

Answer 4

House nephrons with their function of filtration and reabsorption

Question 5

What forms the renal pelvis and where is this found?

Answer 5

Minor calyces that converge on major calyces form the renal pelvis found at the hilum of the kidney

Question 6

What does the renal pelvis do?

Answer 6

Transports urine to the bladder

Question 7

What are the different components of the nephron?

Answer 7

renal corpsucle/glomerulus
proximal convoluted tubule
loop of henle
distal convoluted tubule
collecting duct

Question 8

What are the 2 types of nephron?

Answer 8

Juxtamedullary

Superficial

Question 9

Properties of juxtamedullary nephron

Answer 9

Recieves 10% of renal supply
Concentrates urine
Has glomeruli in inner cortical regions
Has long nephron loops
Associated with vasa recta

Question 10

Properties of superficial nephron

Answer 10

Receives 90% of renal supply
Resorbs large amount of fluid that filters from vasculature
Has glomeruli in outer cortical regions
Has short nephron loops

Question 11

Describe the process of urine entering the bladder from the ureter

Answer 11

Urine is channeled by renal calyces and the renal sinus into the ureter. Peristaltic waves propel urine down ureter which fills the bladder by relaxation of the detrusor muscular wall

Question 12

How is the bladder emptied?

Answer 12

By detrusor muscular contraction which is aided by raised intra-abdominal pressure

Question 13

Are the components of the bladder striated/non-striated and voluntary/involuntary?

Answer 13

Muscle is smooth and involuntary

External sphincter found around urethra is striated and voluntary

Question 14

Explain the process of filtering urine

Answer 14

Beginning of urine production:
blood supply enters through renal artery through a
dense network of capillaries in the glomerulus where filtration can take place
high hydrostatic pressure forces plasma through capillaries and forces out ultrafiltrate
fenestrations allow filtration of unwanted substances such as water out and keeps desired substances in such as plasma proteins
circulation leaves again filtered into Bowman’s capsule through podocytes ready for entry into tubule of nephron

Question 15

What are podocytes?

Answer 15

Make up epithelial lining in Bowman’s capsule

Question 16

What is the kidney’s function as an excretory organ?

Answer 16

Cleanses the blood of metabolic end products/toxins/water that may be surplus to body’s needs

Question 17

What is the kidney’s function as a homeostatic and endocrine organ?

Answer 17

controls blood pressure levels, tissue osmolality and electrolyte levels

Question 18

What is reabsorption?

Answer 18

Transferring water and solutes from the lumen of nephron tubules to the interstitium to come back into circulation

Question 19

Describe the 2 different paths of reabsorption

Answer 19

Paracellular: substances reabsorbed can enter through tight junctions, passive process
Transcellular: through cells of the nephron through channels and transporters, active process requiring energy from Na/K-ATPase

Question 20

Explain how transcellular reabsorption occurs

Answer 20

Na/K-ATPase creates a Na gradient between outside and inside of cell
Ion transport results in voltage gradient between tubule lumen and interstitium
Water follows Na by osmosis entering the basolateral domain carrying solutes

Question 21

What are the components of what is excreted out in urine?

Answer 21

what is filtered out - what is reabsorbed + what is secreted later on
hormonal regulation plays a major role

Question 22

What are the surface modifications of proximal tube of the kidney nephron epithelial cells?

Answer 22

Have apical microvilli that increase the surface area

Have junctions between cells which are leaky and maximise free flow of water and dissolved solutes

Question 23

How is Na reabsorbed by the proximal tube of the kidney nephron?

Answer 23

Driven by basolateral Na/K-ATPase through cotransport with organic solutes in exchange for H+

Question 24

How is Cl- absorbed by the PT of the kidney nephron?

Answer 24

Occurs in the late proximal tube by paracellular route or by a Cl- base exchanger

Question 25

How is water reabsorbed by the PT in the kidney nephron?

Answer 25

Occurs by osmosis, driven by influx Na, Cl and solutes

Question 26

What is the role of the peritubular network?

Answer 26

Returning reabsorbed fluid to the vasculature

Question 27

What occurs during a spinal micturition reflex?

Answer 27

Parasympathetic motor efferents stimulate bladder contraction. Emptying of the bladder is prevented by the CNS until the outer sphincter is relaxed voluntarily

Question 28

What is micturition?

Answer 28

Urinating

Question 29

What triggers a spinal micturition reflex?

Answer 29

The bladder filling stretching its muscular wall