urinary system

Question 1

organs of the urinary system

Answer 1

• 2 kidneys
• 2 ureters
• urinary bladder
• urethra

Question 2

ureter function

Answer 2

passageway for urine
From renal pelvis to urinary bladder
Lined with transitional epithelium which can change shape and flatten depending on volume of urine
Ureters on an angle to prevent back flow of urine, back flow of urine leads to urinary tract infections

Question 3

urinary bladder function

Answer 3

hollow muscular container located in pelvic cavity posterior to symphysis pubis
Transitional epithelium lines the bladder
In an empty bladder there is 5-6 layers but as the bladder expands the epithelium stretches and decreases to 1-2 layers

Question 4

urethra function

Answer 4

transports urine from the urinary bladder to the outside of the body

Question 5

male vs female urethra

Answer 5

Male urethra: a lot longer then females, extends from the inferior part of the unitary bladder to the tip of the penis
Female urethra: shorter, this is why females are more prone to urinary tract infections then males

Question 6

Describe the main functions of the kidneys.

Answer 6

Excretion - get rid of waste products
Eliminating wastes from the body eg urea and creatinine
Regulating the concentration of solute in the blood
Regulating blood volume and blood pressure
Contributing to synthesis of red blood cells and vitamin D

Question 7

location of the bladder

Answer 7

pelvic cavity

Question 8

location of the kidneys

Answer 8

Left kidney is in left lumbar region
Bladder when it is empty lies in the pelvic cavity

Question 9

3 coverings on the kidney

Answer 9

1. Renal capsule - immediate lining covering the renal tissue
2. Adipose tissue - surrounds the outside of the renal capsule for protection
3. Renal fascia - thin layer of connective tissue surrounds the adipose tissue, anchors kidneys to the abdominal wall

Question 10

what is the nephron

Answer 10

functional unit of kidney which produces urine

Question 11

structure of the nephron

Answer 11

4 regions
1. Renal corpuscle
2. Proximal convoluted tubule
3. Loop of henle
4. Distal convoluted tubule

Question 12

1. Renal corpuscle

Answer 12

filtration portion of the nephron
consists of glomerulus and bowman capsule
Glomerulus - network/ball of capillaries
blood enters glomerulus through afferent arteriole
Filtered blood exists through efferent arteriole becoming filtrate
Bowman capsule - enlarged end of the nephron, double walled chamber, filters blood/fluid which then enters the proximal convoluted tubule

Question 13

Proximal convoluted tubule

Answer 13

main area for reabsorption of water
- many microvilli, mitochondria and active reabsorption

Question 14

loop of henle

Answer 14

has a descending and an ascending limb
- reabsorbs ions and water

Question 15

Distal convoluted tubule

Answer 15

controlled secretion of wastes, toxin, excess ions
alters concentration of urine by varying water reabsorption

Question 16

urine flow

Answer 16

nephron - papillary ducts - minor calyces - major calyces - renal pelvis - ureter

Question 17

2 types of nephrons

Answer 17

Juxtamedullary nephron :
renal capsule is deep in the cortex near the medulla
Long loop of henle extending deep into the medulla
15% of nephrons
2. Cortical nephrons
renal capsule located near the periphery/ cortex
Shorter loop of henle
85% of nephrons

Question 18

Diuretics

Answer 18

eg alcohol and coffee
Make you pass more urine by affecting the amount of water reabsorbed by the kidneys
Drinking to much coffee or alcohol can make you dehydrated because you lose more water in urine then you take in

Question 19

three processes needed for urine formation

Answer 19

1. filtration
2. tubular reabsorption
3. tubular secretion

Question 20

filtration step of urine formation

Answer 20

occurs in the renal corpuscle
Blood enters the glomerulus, the fluid and solutes in the blood are pushed through try glomerular capillary wall and enter the Bowmans capsule, solution is filtrate
Average urine production is 1-2L a day

Question 21

tubular reabsorption step urine formation

Answer 21

return of water, small molecules and ions back into the blood
Filtrate flows through the proximal convoluted tubules, loop and henle, distal convoluted tubules and then to the collecting ducts
Reabsorbed to the blood via diffusion, facilitated diffusion, active transport, symport and osmosis
Solutes that are reabsorbed include amino acids, glucose, fructose and ions
As solutes are reabsorbed water follows via osmosis

Question 22

tubular secretion step of urine formation

Answer 22

Substances secreted into the filtrate from the blood
Active or passive

Question 23

Describe the components that make up the filtration membrane.

Answer 23

Fenestrae: holes in the endothelial cells of the glomerular capillaries
glomerular capillaries are highly permeable
2. Basement membrane: sandwiched between the endothelial cells of the glomerular capillaries and the podocytes
3. Filtration slits: gaps between the cell processes of the podocytes
the filtration membrane needs to be intact to prevent large particles like red and white blood cells passing through
If any of these are present in the urine this suggests there is damage to the renal corpuscle

Question 24

Explain how substances are able to move across the cell membranes of the nephron.

Answer 24

Sodium potassium exchange pump
active transport
Moves against concentration gradient
Na+ is pumped out of the cell, K+ is pumped into the cell
Antiport / Counter transport: moving in opposite direction to Na+
Facilitated diffusion:
sugars eg glucose, amino acids and K+ all exit the nephron this way
Down the concentration gradient from high to low
Passive (doesn’t require ATP)
Molecules can move in or out it just depends on the concentration gradient

Question 25

9. Describe the specific movement of glucose across the cell membranes of the nephron.

Answer 25

Co transport - symport
how glucose moves from the filtrate into the nephron cells by piggybacking in with Na+ which is passively entering
Glucose moving against their concentration gradient
Facilitated diffusion: glucose moves out of the nephron cell using proteins into the blood
glucose is in high concentration within the nephron cell (came into the cell with the Na+ via symport)
Glucose is moving from the filtrate to the blood, it is being reabsorbed into the body where it will be used by cell to make ATP

Question 26

10. List the waste products excreted in urine.

Answer 26

95% water
Urea
Amino acids eg ammonia, sulphate