the nervous system

• the human nervous system is a complex network of nerve cells that carry messages to and from the brain and spinal cord to different parts of the body. It helps all the parts of the body to communicate with each other.
• The CNS, has two main functions: the control of behaviour and the regulation of the body's physiological processes.
• The spinal cords main function is to relay information between the brain and the rest of the body.
• The spinal cord allows the brain to monitor and regulate bodily processes, such as digestion and breathing.
• The spinal cord is connected to different parts of the body by pairs of spinal nerves, which connect to specific muscles and glands.
• if the spinal cord is damaged, areas supplied by spinal nerves below the damaged site will be cut off from the brain and will stop functioning.
• the brain can be divided into four main areas: cerebrum, cerebellum, brainstem, and diencephalon.
• the cerebrum is the largest part of the brain, and is further divided into four different lobes.
• the cerebrum is split into two halves called the cerebral hemispheres. Each hemisphere is specialised for particular behaviours, and the two halves communicate with each other through the corpus callosum.
• the cerebellum sits beneath the back of the cerebrum, it involved in controlling a person's motor skills and balance, coordinating muscles.
• the diencephalon lies beneath the cerebrum and on top of the brain stem, within this there are two important structures, the thamalus and the hypothalamus.
• the thamalus acts as a relay station for nerve impulses coming from the senses, routing them to the appropriate part of the brain where they can be processed
• the hypothamalus regulates body temperature, hunger and thirst. it also acts as a link between the endocrine system and the nervous system, controlling the release of horomones from the pituitary gland.
• the brain stem is reponsible for regulating the autonomic functions that are essential for life, such as breathing, heartbeat and swallowing.
• the function of the peripheral nervous system is to relay nerve impulses from the CNS to the rest of the body and from the body back to the CNS
• the somatic nervous system contains both sensory and motor neurons. sensory neurons relay messages to the CNS, and motor neurons relay information from the CNS to other area of the body. its also involved in reflex actions without the involvement of the CNS, which allows the reflex to occur very quickly.
• the autonomic nervous system governs the brain's involuntary activities, and is self regulating. it is divided into the sympathetic and the parasympathetic branch
• the sympathetic nervous system is primarily involved in the flight or flight response, increasing heart rate and blood pressure and dilating blood vessels in muscles.
• the parasympathetic nervous system relaxes the individual once the emergency has passed, slowing down the heartbeat and blood pressure, digestion begins again. it is known as the bodys rest and digest system.