Anatomy of Renal system

Function of urinary system

• Filter blood, form urine & excretion of waste products

• Regulate water, electrolyte & acid base balance

• Produce some hormone & participate in metabolism of others

• Rest; estimated 20% of cardiac output (~1000ml/min) flows through kidney where it's filtered & reconditioned

Kidney anatomical position

• Lie on posterior abdominal wall, one on each side of vertebral column, behind peritoneum & below diaphragm

• Located retroperitoneal of abdominal cavity

• Partially protected by 11&12 pairs of rib

• Right is slightly lower than left kidney (space occupied by liver)

Kidney gross anatomy

• Shaped: bean-shaped, with medial concavity & lateral convecity

• Weight: male,150-200g & female 120-135g

• Size Adult: (12 × 6 × 2.5)cm long x wide x width

• Near concave border is deep fissure called renal hilus

• Blood vessel, lymphatic vessel & nerve enter & exit kidney through hilus

Kidney function

• Urine formation by filtration & selective reabsorption processes

• Receives 1.2 liter/min of blood

Anatomical position of Ureter

• Starts at renal pelvis, located at hilum of kidney.

• Runs down retroperitoneum, anterior to psoas major muscle & crosses under gonadal vein

• Ureter then curves laterally into pelvis, crosses iliac vessels & enter base of bladder

Gross anatomy of Ureter

• Length: muscular tube; 25-30 cm long & 0.3 cm wide in adults

• Shape: S-shaped; travel from kidney to bladder

• Segments: 3 segments - proximal, distal & intramural

Function of Ureter

• Propel urine from kidney into bladder by peristaltic contraction of smooth muscle layer

• Intrinsic property of smooth muscle & not under autonomic nerve control

• Waves of contraction originate in pacemaker in minor calcyes

• Peristaltic waves occur several times per minute, increasing in frequency with volume of urine produced & send little spurts of urine in bladder

Anatomical position of Urinary Bladder

• Located in the pelvis, behind the pubic bones, and extends into the abdomen when full.

• Located in the lower abdomen and pelvic cavity, and its position changes depending on how full it is

• When empty: The bladder is in the lesser pelvis.

• When full: The bladder extends into the abdominal cavity.

• In children: The bladder is in the abdomen until puberty.

Gross anatomy of Urinary Bladder

• Urinary bladder is a sac that stores urine before it's expelled through the urethra.

• Apex or dome: The top-front part of the bladder that points toward the abdominal wall

• Body: The large area between the apex and the fundus

• Fundus or base: The bottom-back part of the bladder

• Neck: The narrow group of muscles that connect to the urethra

Function of Urinary Bladder

Stores & release urine

Anatomical position of Urethra

• In the pelvic region of the body that carries urine from the bladder to the outside of the body. The anatomical position of the urethra varies between males and females:

• Female: about 4 cm long and starts at the bladder neck. It passes through the pelvic floor muscles and opens into the vestibule, the area between the labia minora. The urethral opening is in front of the vaginal opening and behind the clitoris.

• Male: includes the prostatic urethra, which passes through the prostate gland. The prostatic urethra is surrounded by smooth muscle and is most commonly affected by benign prostatic hyperplasia (BPH).

Gross anatomy of Urethra

• Tube in the pelvic region that carries urine out of the body. It has several anatomical features, including:

• Layers: three coats: a muscular layer, an erectile layer, and a mucous layer. The muscular layer is a continuation of the bladder's muscular layer.

• Sphincters: 2 sphincters, or muscles that act as valves to open and close:

  1. External xternal urethral sphincter: Located in the pelvic floor

  2. Internal urethral sphincter: Located at the point where the urethra leaves the bladder.

• Lining: varies by segment, but it's made up of epithelial tissue, smooth muscle cells, and connective tissue:

  1. Prostatic urethra: Lined with transitional cell epithelium (urothelium)

  2. Membranous urethra: Lined with stratified columnar and pseudostratified epithelium

  3. Penile urethra: Lined with stratified columnar and pseudostratified epithelium, with stratified squamous epithelium distally

• Glands: small mucus-secreting glands, as well as bulbo-urethral glands of Cowper, that secrete mucous to lubricate the urethra

• Vascular submucosa: membranous urethra has a rich vascular submucosa that provides urethral occlusive pressure

Function of Urethra

Allows urine to pass out of the body and has other functions depending on the sex of the person:

• Urination: The urethra allows urine to exit the body after the brain signals the bladder muscles to tighten and the sphincter muscles to relax.

• Sperm and semen release: In males, the urethra is also used to release sperm and semen.