THE ORGANISATION OF THE URINARY SYSTEM- blogwriterjony

The urinary system consists of the following organs:

1. 2 kidneys, which secrete urine. 

2. 2 ureters, which convey the urine from the kidneys to the urinary bladder.

3. The urinary bladder where urine collects and is temporarily stored.

4. The urethra through which the urine is discharged from the urinary bladder to the exterior.

Excretory organs of the body :

1. Kidneys - excrete metabolic waste products.

2. Skin -excretes sodium chloride in sweat, urea and arometic substance, eg ;gralic.

3. Lungs - excrete the carbon dioxide generated by cells. 

4. Liver - small amounts of metabolic waste products are excreted in liver bile.

5. Intestines- A variable amount of water is lost in faeces.

KIDNEYS:

Functions of the kidneys:

 1. Excretion of metabolic waste products and foreign chemicals by formation of urine. 

2. Regulation of water and electrolyte balances.

3. Regulation of body fluid osmolality and electrolyte concentrations.

4. Regulation of arterial pressure. 

Constriction of the ureter :

   1. At the ureteropelvic joint (just inferior to kidney)

2. Where  the ureters cross the common iliac vessels at the pelvic brim.

3. Where the ureters enter the wall of the urinary bladder. 

Structure of the ureter:

1. An outer covering of fibrous tissue.

2. An intermediate muscular layer (smooth muscle)

3. An innermost mucous membrane, lined by transitional epithelium.

Function of ureters :

The ureters propel urine from the kidneys into the urinary bladder by peristaltic contraction.

Uranary bladder:

The urinary bladder is a temporary muscular reservoir of urine, that lies in the anterior part of the pelvic cavity.

Shape,size and position :

 The urinary bladder varies in size, shape and position depending on the volume of urine it contains 

A full bladder is ovoid in shape. 

When empty, it is entirely situated in the pelvic cavity, it expands superiorly into the abdomen when full.

External features(parts):

The urinary bladder has:

1. An apex

2. A base

3. A neck 

4. Three surface - 1 superior Surface and 2 inferolateral surfaces. 

Interior of the bladder :

1. When empty, the inner lining is arranged in folds or rugae. 

2. The three orifices in the bladder wall form a triangle or trigone.The upper two orifices on the posterior wall are the openings of the ureters. The lower orifices is the opening into the urethra. 

Capacity of the bladder :

 The mean capacity of the bladder in an adult male is 220 ml, varying from 120 to 320 ml. Filling over 220 ml causes a desire to micturate. Total capacity may be up to 500 ml.

Function of urinary bladder :

1. The urinary bladder is the temporary store house of a reasonable volume of urine. 

2. When it is distended beyond the capacity, there is in built mechanism of voiding of urine through urethra.