The Nervous System - receives, transmits and stores information in order to coordinate body functions so that they work in harmony. - is composed of a) the central nervous system CNS (brain and spinal cord) b) the peripheral nervous system PNS ( the nerves)

Neurons Nerve cells that receive and transmit messages. 4 parts: dendrites, cell body, axon, axon terminals Neurons - pick up stimuli (hormones, light, odours,etc) - transform them into nerve impulses (electrical signals) - then transmit them.

Characteristics of Neurons 1. React to stimuli by changing into electrical signals ( nerve impulses). 2. Are conductive; transmit nerve impulses from one neuron to another. 3. Consume a lot of Oxygen and Glucose – can only survive a few minutes without oxygen. 4. Can live for more than 100 years. 5. Can't reproduce – cannot be replaced if destroyed.

Transmission of nerve impulses 1. Dendrites receive messages (stimuli) and transform them into nerve impulses. 2. Nerve impulses are transmitted along axons to axon terminals. 3. Nerve impulses travel from one neuron to another via Neurotransmitters Neurotransmitters are chemical substances secreted by axon terminals across synapses. Synapses are transition zones between 2 neurons

Nerves Sometimes the axons of neurons combine to form nerves. A nerve is a structure that helps transmit information between the central nervous system and different regions of the body. The Peripheral Nervous System is made up of all the nerves that run throughout the body. It connects the body to the CNS (Brain and spinal cord)

Peripheral Nervous System (PNS) The PNS connects different parts of the body to the Central Nervous system (CNS) Sensory receptors (ex. rods,cones) detect stimuli and send messages through sensory nerves to the CNS. Stimulus Sensory Sensory CNS Muscles (sound) receptors nerves (brain,spinal cord)

Sensory Nerves: Transmit information picked up by sensory receptors to the CNS Ex. Sensory receptors around the heart can pick up high blood pressure and transmit this information to the CNS. Motor Nerves: Transmit information from the CNS to the muscles. This stimulates muscles to produce voluntary and involuntary movements.

Central Nervous System Composed of the Brain and the Spinal cord Brain communicates with the organism through cranial nerves. The Cerebrum is the control center of: 1) voluntary movement: Cerebrum's motor cortex sends nerve impulses to muscles stimulating contraction (ex. to lift your arm) 2) sensory interpretation: Cerebrum receives information from sensory nerves, analyzes and interprets it.

3) intelligence and emotion: Cerebrum controls intellectual activities like reading and problem solving. It also manages emotion like joy and sadness. Physiological functions: regulated by the Hypothalamus located below the Cerebrum. - controls the pituitary gland - hunger, thirst, temperature regulation, alertness

Cerebellum: Keeps your balance and coordinates movement like walking straight, dancing, good posture. Brain Stem controls: internal stimuli and involuntary movement in your internal organs.

The Spinal Cord Carries nerve impulses between the body and the brain via spinal nerves. Protected by the bones of the spinal column called vertebrae It is also the reflex centre. A reflex is a rapid and involuntary reaction to stimulus.

Reflex Arc Path taken by a nerve impulse during a reflex. Stimulus Sensory nerve spinal cord motor nerve muscle