The Peripheral Nervous System Subtitle

The Spinal Cord ▪ Function: to relay information to and from the brain ▪ Description: white cable around 43cm long and 2 cm wide ▪ Your spinal cord is a glistening white bundle of nerves, which runs from the brain down a canal in your backbone ▪ Its main function is to relay information about what is happening inside and outside your body and from your brain

Peripheral Nervous System ▪ Has 2 parts: – The somatic nervous system – The autonomic nervous system

Somatic Nervous System ▪ Collects information through the sensory organs ▪ Also coordinates movement of the body ▪ The somatic nervous systems sensory organs are receptors – special organs or tissue that have nerve endings that detect changes in the environment

▪ In your body there are different types of receptors ▪ Mechanoreceptors sensitive to stimuli such as touch; they also make you aware of muscles being stretched ▪ Photoreceptors in the eye are sensitive to light ▪ Thermoreceptors respond to temperature changes ▪ Chemoreceptors are sensitive to chemicals, such as those found in food

The Sensitive Skin ▪ Skin responds to many different sensations, such as touch, pain and temperature ▪ Being sensitive to touch is one way your body protects itself

The Sense of Hearing ▪ Sometimes receptors are grouped together to form a sense organ, like the ear ▪ The ear not only senses sound, but also helps you to keep you balance ▪ Any noise you hear set up a range of vibrating particles in the air ▪ These particles enter your ear as waves and causes the eardrum to vibrate ▪ The vibrations are transferred along the bones of the middle ear – the smallest bones in your body – and converted to nerve impulses ▪ The brain interprets the information, telling you what you are hearing

The Sense of Sight ▪ The pupils change size to control how much light enters the eye ▪ Light entering the eyes forms an upside down image on the back of the eye ▪ The photoreceptor cells here transform the light into nerve signals for the brain, which tells you what you are seeing

A Sense of Smell ▪ Our perception of smell depends on chemical receptors that are found in each of our nostrils ▪ These receptors detect airborne chemicals and then send messages to the brain, which interprets the message and tells us what we are smelling ▪ Smell is closely linked to taste

A Sense of Taste ▪ If you look at your tongue in a mirror you will be able to see thousands of timey taste buds ▪ Taste buds contain special receptors cells that react to chemicals in foods ▪ Taste buds can recognise basic kinds of taste: sweet, salty, sour and bitter ▪ The areas for these four kinds of taste are located in different parts of the tongue ▪ When eating or drinking, the information from the taste receptors cells is sent to the brain, which tells you what you are tasting

Autonomic Nervous System ▪ The autonomic nervous system directs all activities of the body that occur without a person’s conscious control, such as breathing and food digestion. ▪ It has two parts: – the sympathetic division which is most active in times of stress, and – the parasympathetic division, which controls maintenance activities and helps conserve the body’s energy.