EXCRETORY SYSTEM
The Excretory system plays a major role in the removal of waste from the body in the form of urea.
The human excretory system is situated in the dorsal side of the pelvic cavity .
PARTS OF EXCRETORY SYSTEM
The excretory system consists of a pair of kidneys. The kidney is red bean shaped organ which consists of small units known as the nephrons, which play a major role in the filtration of water and formation of urine. The longitudinal section of kidney consists of a dotted cortex and lighter medulla.
The outer cortex continues into inner medulla.
The Tranverse section of the kidney shows the unit of kidney known as nephron.
The nephron consists of a cup shaped Bowman's Capsule consists of a network of blood vessels and capillaries known as Glomerulus. The Bowman's capsule continues into a tubular convoluted tubule, Proximal convoluted tubule . The The Proximal convoluted tubule continues as ascending limb, loop of Henle, Descending limb, Distal convoluted tubule and collecting tubule.
A network of connective tubule continues into pelvis which is formed by the union of calyces and renal pyramids present in the renal medulla.
The tip of the kidney is known as the Hilus, the place from where the pelvis arises and continues into a narrow tube called Ureter. The Renal Hilus consists of a renal vein and a renal artery , which supplies blood to the kidney.
Structure of Nephron (Transverse Section of kidney )
Location of kidneys
Ureter is a narrow tube like structure which carries the filtered urine and enters into a bag like structure known as the Urinary Bladder.
Urinary Bladder is a muscular bag like structure which has the capacity for storage of one liter of urine. Once the bladder is full, the bladder opens up the sphincters and gives rise to urination , right through the urethra ad out of the body from the urinary orifice (urinary opening ) .
Parts of excretory system
PROCESSES OF KIDNEY
There are four basic processes in the formation of urine starting with the plasma .
Structure of Nephron (Transverse Section of kidney )
Location of kidneys
Ureter is a narrow tube like structure which carries the filtered urine and enters into a bag like structure known as the Urinary Bladder.
Urinary Bladder is a muscular bag like structure which has the capacity for storage of one liter of urine. Once the bladder is full, the bladder opens up the sphincters and gives rise to urination , right through the urethra ad out of the body from the urinary orifice (urinary opening ) .
Parts of excretory system
PROCESSES OF KIDNEY
There are four basic processes in the formation of urine starting with the plasma .
- FILTRATION - It is the mass movement of water and solid substances from plasma to renal tubule that occurs in the renal corpuscle. About 20% of the plasma volume passing through the Glomerulus at any given time is filtered. Around 180 Litres of fluid are filtered by kidneys everyday. Thus, about 3 litres of plasma is filtered 60 times a day.
2. REABSORPTION - it is the movement of water and solutes from the tubule back into the plasma . Bulk reabsorption, which is not under hormonal control, occurs largely in the proximal tubule. Further bulk reabsorption of sodium in the loop of Henle. Regulated reabsorption, in which hormone control the rate of transport of sodium and water depending on systemic conditions, takes place in the distal tubule and collecting duct.
3. SECRETION- Even after filtration has occurred the tubules continue to secrete additional substances into tubular fluid. This enhances the kidney's ability to eliminate certain wates and toxins.
4. EXCRETION - Removal of urine out of the body
DISEASES OF EXCRETORY SYSTEM
GLOMERULONEPHRITIS - It is also called glomerular nephritis. In this disease, the glomerulus , which is an intertwined group of capillaries as a part of the nephrons undergoes inflammation. This can cause acute renal failure too and may cause other disorders like fever, diarrhoea, cough, etc.
HORSESHOE KIDNEY- This is a congenital disorder in which the two kidneys of the patient fuse together to form a horseshoe shape while the child was developing in the womb. It is the most common renal fusion anomaly. Horseshoe Kidney may be a reason for kidney stones or kidney cancer too.
URINARY TRACT INFECTION - Urinary tract infection is a bacterial infection in any part of a urinary tract. Usually urine does not contain bacteria in it, but if it multiplies in any part of the tract. The most common Escherichia Coli.
KIDNEY STONES- It is a disorder in which any part of the urinary tract, basically the ureter gets constricted by stones, which are solid concretions formed in the human kidneys from dissolved urinary minerals. It may obstruct proper urine excretion.
A video on the formation of renal calculi or kidney stones
GOUT- In this disorder, the body builts up excess amount of uric acid as the kidneys fail to process it properly.
URETHRIS - This is a disease which is characterized by the inflammation of the urethra. It can lead to painful and difficult urination experience.
