The tendency of the body to seek and maintain a balance condition or equilibrium within its internal environment, even when faced with external challenges is called homeostasis

Skin eliminates metabolic wastes through perspiration. Hence it has an excretory role also.

The testes apart form producing sperms also produces male sex hormone called testosterone. Similarly the ovary apart from producing the ovum also produces the female sex hormone called oestrogen. Hence the gonads are also considered as endocrine glands.

a. The two testes lie in the respective scrotal sacs. The scrotum acts as a thermoregulator organ and provides an optimum temperature for the formation of sperms. The sperms develop at a temperature of 1-3°C lower than the normal body temperature. Hence scrotum remains outside the body of human males.
b. The wall of the stomach is protected by mucus. Hence the wall of the stomach is not digested by its own enzymes. Further the gastric enzyme pepsinogen is present only in inactive form and converted into active pepsin only when food enters the stomach

Functions of ovaries :
(i) The ovaries are the female gonads which produce ova or the female gametes.
(ii) They also secrete the female sex hormones namely oestrogen and progesterone.
Functions of uterus :
(i) Uterus is a pear-shaped muscular, hollow structure present in the pelvic cavity.
(ii) Development of foetus occurs inside the uterus

Each kidney consists of more than one million nephrons. Nephrons or uriniferous tubules are structural and functional units of the kidneys. Each nephron consists of Renal corpuscle or Malphigian corpuscle and renal tubule. The renal corpuscle consists of a cup-shaped structure called Bowman's capsule containing a bunch of capillaries called glomerulus. Blood enters the glomerular capillaries through afferent arterioles and leaves out through efferent arterioles. The Bowman's capsule continues as the renal tubule which consists of three regions proximal convoluted tubule, U-shaped hair pin loop, the loop of Henle and the distal convoluted tubule. The distal convoluted tubule opens into the collecting tubule. The nitrogenous wastes are drained into renal pelvis of kidney which leads to ureters and stored in the urinary bladder. Urine is expelled out through the urethra.

Starch      - Glucose
Proteins    -Amino acids
Fats Fatty -acids and glycerol

Permanent teeth are of four types (Heterodont), according to their structure and function namely incisors, canines, premolars and molars.

a. Digestion:The breakdown of large complex insoluble food molecules into small, simpler, soluble and diffusible particles by the action of digestive enzymes is called digestion.
b. Osmoregulation:The maintenance of constant osmotic pressure in the fluids of an organism by the control of water and salt concentrations
c. Emulsification:Bile salts help in the digestion of fats by bringing about their emulsification (conversion of large fat droplets into small ones).
d. Ovulation:The process of release of ovum from the ovary is known as ovulation.