HOMEOSTASIS IN HUMANS

 HOMEOSTASIS IN HUMANS

•humans have highly developed systems for homeostasis.

•The following are the main organs which work for homeostasis:

•Lungs remove excess carbon dioxide and keep it in balance.

•Skin performs role in the maintenance of body temperature and also removes excess water and salts.

•The kidney filters excess water, salts, urea, uric acid etc. from the blood and forms urine.

Skin

•Epidermis is the outer protective layer without blood vessels while dermis is the inner layer containing blood vessels, sensory nerve endings, sweat and oil glands, hairs and fat cells.

• Metabolic wastes such as

     excess water, salts, urea

     and uric acid are also

     removed in sweat.

Skin

Lungs

•lungs maintain the concentration of carbon dioxide in the blood. Our cells produce carbon dioxide when they perform cellular respiration. From cells, carbon dioxide diffuses into tissue fluid and from there into blood. Blood carries carbon dioxide to lungs from where it is removed in air.

THE URINARY SYSTEM OF HUMANS

•The excretory system of humans is also called the urinary system. It is formed of one pair of kidneys, a pair of ureters, a urinary bladder and a urethra. Kidneys filter blood to produce urine and the ureters carry urine from kidneys to urinary bladder. The bladder temporarily stores urine until it is released from body. Urethra is the tube that carries urine from urinary bladder to the outside of body.

THE URINARY SYSTEM OF HUMANS

Structure of Kidney

•Kidneys are dark-red, bean shaped organs.

•Each kidney is 10 cm long, 5 cm wide and 4 cm thick and weighs about 120 grams

Structure of Kidney


Functioning of Kidney

•The main function of kidney is urine formation, which takes place in three steps.

•Pressure filtration

•Selective re-absorption

•Tubular secretion

Water	95%
Urea	9.3 g/I
Chloride ions	1.87 g/I
Sodium ions	1.17 g/I
Potassium ions	0.750 g/I
Other ions and compounds	Variable amounts

Normal chemical composition of Urine 

Osmoregulatory Function of Kidney

•“The regulation of the concentration of water and salts in blood and other body fluids.”

•hypotonic

•Hypertonic

   This whole process is under hormonal control.

DISORDERS OF KIDNEY

•There are many different kidney disorders.

•Kidney Stones

•Kidney (Renal) failure

    Dialysis (Dialysis means the cleaning of blood by artificial ways.) There are two methods of dialysis.

1.Peritoneal Dialysis

DISORDERS OF KIDNEY

 Haemodialysis

•In haemodialysis, patient’s blood is pumped through an apparatus called dialyzer. The dialyzer contains long tubes, the walls of which act as semi-permeable membranes.

Kidney Transplant

• It is the replacement of patient’s damaged kidney with a donor healthy kidney.

•Kidney may be donated by a deceased-donor or living-donor. The donor may or may not be a relative of the patient. Before transplant, the tissue proteins of donor and patient are matched. The donor’s kidney is transplanted in patient’s body and is connected to the patient’s blood and urinary system. The average lifetime for a donated kidney is ten to fifteen years. When a transplant fails, the patient may be given a second kidney transplant. In this situation, the patient is treated through dialysis for some intermediary time. Problems after a transplant may include transplant rejection, infections, imbalances in body salts which can lead to bone problems and ulcers.