Nervous system and sensory system

The bones of the skull and backbone protect the soft brain and spinal cord. Fibres called nerves pass from the brain and spinal cord to all parts of the

Messages pass from the various parts of the body along the nerves to the brain. The brain sends a message back telling the different parts of the body what to do. The brain controls the body. The brain also controls the senses, the sense organs are:

· the eyes for sight
· the ears for hearing
· the nose for smell
· the tongue for taste
· the skin for touch

Reproductive system (breeding)

The male reproductive organs, the testicles, lie in the scrotum behind the penis. The testicles produce sperm which are contained in the fluid semen. A tube passes from each testicle and joins to form a tube which runs down the centre of the penis.

In the bird the testicles are inside the body.

The female reproductive organ consist of two ovaries, one in each side of the lower abdomen. The ovaries produce eggs which pass into the uterus (or womb). Below the uterus is the vagina which opens to the outside surrounded by the vulva. After birth the young are fed on milk produced by the udder. During mating sperm passes from the male into the uterus and joins with the eggs there. When the sperm joins the egg it forms the embryo which develops into the young animal inside the uterus. Reproduction is controlled by hormones (chemical messengers) which are carried in the blood to the different organs. These hormones control:

· Puberty of the animal
· Production of eggs
· Birth
· Production of semen
· Development of the embryo
· Milk production

Lympho-reticular system

Lymph is a colourless fluid which passes out of the blood into a network of fine tubes called the lymphatic system. It passes through the lymph nodes, where germs are filtered out and killed, before it is returned to the veins. The lymph nodes and spleen also produce special blood cells which protect the body against disease. Sometimes when an animal is infected the lymph nodes become swollen and can be felt beneath the skin.

Control questions:

What are the various organs of the body?

What are the positions of the main organs within the body?

Date: 2016-04-22; view: 947