Anatomy and Histology

Storage of urine until it can be discarded

1) Three layer:

1. 1)  Mucosa with distensible transitional epithelium and lamina propria. Mucosal lining highly folded-- rugae: stretch and distend

2. 2)  Thick muscularis = detrusor muscle
   Loosely arranged layers of smooth muscle and elastic fibres that contract during micturition: inner longitudinal + outer circular + outermost longitudinal

3. Adventitia: fibrous layer, rich in blood and lymphatic vessesl 

1. 1)  In females, it extends 3‐5 cm from the (external) urethral sphincter muscle at the neck of the urinary bladder to the external urethral orifice, anterior to the vaginal orifice

2. 2)  In males, it extends 18‐20 cm from the neck to the tip of the penis, with three portions with functional differences

   1. 1)  Prostatic urethra passes through the prostate gland

   2. 2)  Membranous urethra penetrates the urogenital diaphragm

   3. 3)  Spongy urethra extends from the base to the tip of the penis 

1. 1)  Initially transitional cells as it exits the bladderthen there are pseudostratified columnar and stratified columnar epitheliathen stratified squamous cells near the external urethral orifice.

2. 2)  There are small mucus‐secreting urethral glands, that help protect the epithelium from the corrosive urine.

3. 3)  Lamina propria is thick and elastic, well vascularised

4. 4)  Surrounded by concentric layers of smooth muscle: muscularis 

•  Endocrine glands

•  Ca. 7.5g, yellow-ish, sit atop the kidneys, i.e. also retroperitoneal

•  Function: Production of adrenaline, aldosterone and cortisol

•  Dense fibrous capsule

•  Highly vascularised

•  Secretes over 24 different hormones (adrenocortical steroids/corticosteroids)

•  Affect metabolic operations primarily by influencing gene transcription