THE ORGANS OF THE SENSES AND THE NERVOUS SYSTEM
Unit 1 Jorge 6ยบ ep
1. We perceive the world around us Each system (digestive, circulatory, respiratory, ‌) consists of organs.
The organs of our body are made of tissues. Tissues are collections of cells that have certain size and shape. The nervous system enables us to control what our body’s systems do, perceive the outside world and react to what we perceive.
Stimuli and Responses A stimulus is any signal that the nervous system receives from inside or outside our body. Each time the nervous system receives a stimulus, it produce a response. There are two kinds of responses: • Involuntary (like being hungry). • Voluntary (decisions we make). When we learn, we perceive, interpret and value certain stimuli in different ways.
2. The organ of the Senses Our Sense of Sight
• Light enters cornea and pupil. • Crosses the lens. • Is regulade by the iris. • Reaches the retina. • Information is transmitted by the optical nerve. • Information goes to the brain. The eye is protected by eyelids, eyelashes, eyebrows and tear glands.
Our Sense of Hearing • Sound travels through the ear canal. • Reaches the eardrum. • The vibrations go to: hammer, anvil and stirrup. • The information is transmitted by the cochlea. • Information goes to the brain.
Our Sense of Smell and Taste • Smells enter the nose. • go to the canal. • reach the olfatory epithelium. • The information is transmited to the brain.
• Our food comes into contact with taste buds • the taste buds are located in our tongue and palate. • The information goes to the brain.
Our Sense of Touch
• Our skin has got an outer layer – Epidermis. • Our skin has got an inside layer – Dermis. • Information goes to the brain.
3. The human nervous system The control nervous system:
• Spinal cord • Brain
The peripheral nervous system: • Nerves Neurons:
• Axon • Dendrites
4. The human brain • The brain stem: controls the involuntary movements. • The cerebellum: controls the voluntary movements. • The cerebrum: receive the information of the senses.
• Protection: skin, skull, cerebrospinal fluid and meninges.
Functions of the brain - Recieve and interpret the information. - Control our ability (learning): speak, write, read, calculate and reason. - Control our voluntary movements. - Centre of:
• Sensations. • Emotions. • Feelings.
- Contains our memory.