Human Excretory System

A. Kidneys B. Urinary tract or Ureter C. Urinary bladder D. Urethra.

are two bean-shaped organs situated in the lower thoracic region of the back

1-Renal Cortex 2-Renal Medulla 3-Renal Pelvis

It is red in color and contains the Malpighian bodies, comprising the Bowman's capsule and glomerulus, which give it its rough structure.

It is located directly beneath the cortex. Urinary tracts which drain from the cortex form pyramids in this region. There are approximately (8-10) laterally arranged Malpighian pyramids. The apex of each pyramid is located in the medulla and its base is located in the cortex.

It forms the inner most portion of the kidney. Its function is the collection of urine from the Malpighian pyramids, the site of 15-20 orifices opening into the pelvis. The pelvis transmits the accumulated urine to the ureter.

nephrons

1200 nephrons

180،،، 1.5

It is a U-shaped, semi-spherical structure. The inner surface consists of squamous epithelial cells. The Bowman's capsule forms the tip of the nephron.

It is a ball of arterial capillaries located in the Bowman's capsule. Each glomerulus is formed by capillaries from a branch of the afferent renal arteriole.

It comprises a Bowman's capsule and glomerulus.

It is beneath the Malpighian body. It is formed from cuboidal epithelial cells.

extends into the loop of Henle and then into the distal convoluted tubule. The total length of these tubules that constitute a nephron in humans is approximately 5 cm.

is the primary nitrogenous waste product, but it is highly toxic. It is the excretory substance of freshwater organisms. Humans produce urea as an excretory product.

 They are muscular tubes which connect the kidneys and the back wall of the bladder.  They transport urine from kidneys to bladder.  Each ureter consists of smooth muscles and each one is (22cm) long.

 It is a sac which stores urine and it consists of smooth muscles.  In the connection point of the bladder with urethra, there are circular striated muscles.  These muscles are voluntary muscles so we can control these muscles or we can control the urination by means of these muscles.  When the bladder contracts, the urination happens.

A. glomerular filtration B. Tubular reabsorbed C. Tubular secretion

 Glomerular filtration of water, various ions, amino acids, sugar and the nitrogenous wastes. These substances pass to the Bowman's capsule from the glomerulus.

 All amino acids, glucose and some urine are reabsorbed at the proximal convoluted tubule.  Sodium, chloride and bicarbonate ions are reabsorbed and are taken up by cells by active transport.  However, 99% of water is reabsorbed passively from different regions of the tubule.

 The cells of the distal convoluted tubule excrete molecules such as penicillin, ammonia, hydrogen, potassium, pigments and excess acids.  At the end, urine is formed and excreted into the urinary bladder via the ureters.