Renal Tubules& Ub & Ureter

Question 1

Talk about proximal tubules

Answer 1

1- it is lined with 4-8 simple cubical
2- highly convuleted
3- the luminal surface has brush borders with long microvilli to incresase the absorptive surface so the lumen is narrow
4- the basal part is rich in mitochondria and basal infoldings
5- acidophilic cytoplasm
6- the cells are tigtly connected together meaning the reabsorbtion is trans cellular

7-function
* active reabsorption to Na (85%)
* passive reabsorption to water (85%)
So it forms an isotonic solution
* reabsorption of glucose, aa and plasma proteins

Question 2

Talk about loops of henle

Answer 2

1- u shape
2- it is formed of 4 parts
• Thick desending part lined with simple cuboidel cells resembling Proximal
2. Thin descending part lined with simple squamous cells
3. Thin assending part lined with simple squamous cells.
( they are permable to water but not permeable to Na they form hypertonic solution)
4. Thick assending part lined with simple cuboidal cells resembling the distal
( it is permabeale to Na but not permeable to water so it forms hypotonic solution)

Isotonic ~> hypertonic~> hypotonic

Question 3

Talk about the distal tubules

Answer 3

1- lined with 6-10 cubical cells
2- acidophilic cytoplasm
3- the luminal surface has less brush borders due to few microvilli so the lumen is wide
4- the basal parts have mitochondria and basal infoldings also
5- function
* reabsorption of water (15%) and na (15%)
By the effect of ADH AND ALDO
* it has macula densa cells that act as ismoreceptors to Na level

Question 4

Talk about collecting tubules

Answer 4

1- lined with simple cubical and end by columner cells
2- the lumen is wide
3- unlike the rest, no microvilli or infoldings or junctions
4- it ends by ducts of bellini
5- function
* conduct and concentrate urine through reabsorption of water and secretion of K by effect of ADH

Question 5

Talk about the ureter

Answer 5

1- 3 layers
• mucosa : Transitional epithelium resting on C.I.corium.( Lamina ProPeria)

-musclosa :Smooth muscles arranged in the upper 2/3 as inner longitudinal and outer circular. In the
lower 1/3 of ureter the smooth muscles are arranged as inner longitudinal, middle circular
and an outer longitudinal.

3. Adventitia:
   - It is formed of elastic C.T. rich in B.V. nerves and lymphatics.

Question 6

Talk about the ub

Answer 6

1- 3 layers
Mucosa: Transitional epithelium resting on a corium of C.T.

Musculosa: Formed of smooth muscles , inner & outer longitudinal and middle circuler ,its fibres run in different directions.
3. Adventitia: Formed of fibro-elastic C.T.

Question 7

Talk about male and female urethra

Answer 7

Male urethra

It is 15-20 cm long.
• It is divided into 3 regions:

A Prostatic part:
• Passes through prostate.
• Lined by transitional epithelium.

B. Membranous part:

• Lined by stratified or pseudostratified columnar epithelium.
• Surrounded by skeletal muscle forming external urethral sphincter.

C. Penile part
• Lined by Stratified columnar that changes to non keratinized stratified squamous

Female urethra
1- 4 :5 cm
2- start with transitional then ends with non keratinized stratified squamous
3- it starts in internal orifice of ub
And ends in external orifice above the vagina