Urinary System

Question 1

What are the 3 main functions of kidneys?

Answer 1

1) . Kidneys maintain blood/water homeostasis via the production of urine
2) . Kidneys monitor and affect the acid/base balance (by excreting hydrogen ions during acidosis or bicarbonate ions during alkalosis

3). Kidneys secrete;
Renin - which raises blood pressure

Erythropoietin - which accelerates red blood cell production

Question 2

What is the function of the ureters?

Answer 2

They conduct urine from. kidneys to the bladder, where it is stored

Question 3

What is the function of the urethra?

Answer 3

The urethra is the passage out of the body (bladder and out)

Question 4

Where are the kidneys located?

Answer 4

The kidneys lie, one on each side, on the posterior abdominal wall, high up, under the diaphragm

Question 5

How are the kidneys protected?

Answer 5

They are retroperitoneal - encapsulated and protected by layers of fascia and fairly. firm renal fat

Question 6

Describe the function of the contents of a kidney and label one?

Answer 6

Cortex (outer portion)

Medulla (inner portion)
- Has renal pyramids which house the nephrons with their function of filtration and reabsorption, projecting into the minor calyces of the collecting system

-The cortex extends between the medullary pyramids as a renal column

The pyramids in medulla open into minor calyces which converge together to form the major calyx, into the renal sinus merging form the renal pelvis at the hilum of the kidney.

The pelvis then becomes the ureter that transports urine to the bladder

Question 7

What is the functional unit within the kidney and what is its role?

Answer 7

The nephron - it’s where urine production takes place

Question 8

What are the regions in a nephron and their functions?

• Draw

Answer 8

1) . Renal corpuscle (glomerulus) - Where the blood supply comes in and filtration takes place
2) . Proximal convoluted tubule (PCT)
3) . Loop of Henle - has a descending and ascending limb with a thick and thin part
4) .Distal convoluted tubule (DCT)
5) . Collecting dust - where a number of different nephrons all merge together

Question 9

What are the 2 types of Nephron and their functions?

Answer 9

1) . Juxtamedullary Superficial;
- Designed to concentrate urine
- Receives 10% of urine supply
- Situated deeper in the kidney
- Glomeruli in inner cortical regions; long nephron loops that go deep down into the medulla

2) . Superficial;
- Reduce the filtering volume
- Receives 90% of renal supply
- Reabsorbs a large percentage of fluid that filters from vasculature
- Located superficially
- Glomeruli in outer cortical regions; short nephron loops

Question 10

What is the urine passage in females and males?

Answer 10

Females;
- Ureter brings urine down, passes it posteriorly to ovary, lateral to cervix and vagina and into the bladder
(females have a very short urethra)

Males;
- Ureter comes down from above into the bladder then into the urethra passing through the prostate and into the penis

Question 11

What muscle relaxes when the bladder fills?

Answer 11

The detrusor muscle

Question 12

What kinds of waves propels urine down the ureter?

Answer 12

Peristalsis

Question 13

What kind of epithelium lines the bladder and what does this allow for?

Answer 13

Transitional epithelium (urothelium) lines the bladder as it is urine proof.

Question 14

What is the glomerulus made up of?

Answer 14

The glomerulus is a ball of many capillaries

Question 15

Where does the filtrate collect?

Answer 15

The filtrate comes out of the capillaries and into the Bowman capsule where it collects, ready to enter the tubule of the nephron

Question 16

How is the filtrate removed from the capillaries?

Answer 16

The high pressure in the capillaries forces the plasma through the capillaries and forces out the ultra-filtrate (start of urine production), separating the plasma from cells and proteins.

Question 17

How is reabsorption done in the kidneys?

Answer 17

Water and solutes are transferred from the lumen of the nephron tubules into the. interstitial so they can come back into circulation again.

Question 18

What are the 2 reabsorption paths?

Answer 18

Paracellular reabsorption - where the substance being reabsorbed back out of the lumen of the nephron can come through tight junctions back into into interstitial and blood vessels

Transcellular reabsorption - Reabsorption through the cells of a nephron, across the apical membrane then from the cell across the basolateral membrane. For this to occur there are various channels. and transporters. to allow for the transport of many substances across the cell.

Question 19

What provides energy for the majority of reabsorption ?

Answer 19

NAATPase

Question 20

How is ion transport powered?

Answer 20

Ion transport creates a voltage gradient between tubule lumen and interstitium, which allows for more. movement of substance across

Question 21

How are solutes transported across?

Answer 21

Solutes are carried along the water flow by solvent drag

Question 22

What happens later on in the nephron?

Answer 22

Other substances are secreted back into/ what is remaining of the ultra-filtrate to get rid of that from the body.

Question 23

What happens in reabsorption?

Answer 23

The ultra-filtrate that has previously been removed from the blood comes back into circulation again

Question 24

What is the countercurrent multiplication mechanism?

Answer 24

The countercurrent multiplication mechanism makes use of the different tissue gradients of osmolarity that the loop of Henle passes through in order to concentrate the filtrate.

Question 25

Where about are the high osmalarities and pressure in the loop?

Answer 25

High osmolarity - DTL (descending thin limb) and around the loop

Water exits the tubule driver by the osmotic pressure gradient

Question 26

How does the Ascending thick limb of the loop prevent water from re-entering and diluting its contents?

Answer 26

It is impermeable so water cannot dilute its contents

Question 27

Where in the kidney are high and low osmolarities found?

Answer 27

High osmolarity - in the medulla

Low osmolarity - in the cortex

Question 28

What occurs after the DCT?

Answer 28

Sodium is removed as there is a very high concentration

Question 29

What. 2 features does the Proximal tubules have, making it better suited to its function?

Answer 29

PT epithelial cells have apical microvilli that increases the surface area + junctions between cells that are leaky. to maximise the free flow of water and solutes

Question 30

How is reabsorbed fluid returned to the vasculature?

Answer 30

Via the peritubular network

Question 31

What is micturition?

Answer 31

Getting rid of the urine formed

Question 32

How is the urine modified after leaving the kidneys?

Answer 32

Urine is not modified after it leaves the kidneys

Question 33

What is present in an empty bladder?

Answer 33

Rugae (folds) on the walls

Question 34

What lines ureters and what does this allow?

Answer 34

Ureters are lined with smooth muscle and transitional epithelium that stretches to allow for urine flow

Question 35

What controls the outflow via the urethra?

Answer 35

The inner and outer sphincters.

Question 36

How does the body detect when the bladder is full and release urine?

Answer 36

When the bladder wall is stretching mechanoreceptors send signals to the pontine micturition (gets rid of urine) but also sends signals via the spinal chord to initiate micturition reflex which causes the Detrusor muscle to contract and increase luminal pressure

Question 37

If we can’t go to the bathroom at that moment what happens?

Answer 37

The micturition reflex is. inhibited but the bladder carries on filling

Question 38

How much can we control. holding in the toilet?

Answer 38

We have a conscious role in when micturition takes. place however, one the bladder reaches. its maximum capacity we don’t