Nervous System

Questions 1. What are the functions of the nervous system? 1. Receives information about what’s happening inside and outside the body. 2. Directs the way that your body reacts to the information. 3. Helps maintain homeostasis (process by which internal environment is kept stable even though outside environment has changed.)

2. What is a stimulus and response? Stimulus is a change in the external or internal environment. Response is how you react to that change. Example = the bell rings at the end of class (stimulus) and you get up to leave (response)

3. What are the 3 kinds of neurons? Sensory, Interneuron, and Motor neurons. Explain what each neuron does: Sensory neurons --- picks up stimuli from the environment by use of senses and converts stimuli into a nerve impulse. Ex. Stimuli --- hunger or a hot stove. Interneuron --- A neuron that carries nerve impulses from one neuron to another. Motor neuron --- Sends an impulse to a muscle, and the muscle contracts in response. (Motor = movement).

Parts of a Neuron Dendrite --- carries impulses toward the axon Axon --- carries impulses away from cell body Cell Body – Has a nucleus & extensions attached. Nucleus – Helps to send the message.

Connections Between Neurons Synapse: the gap between one neuron’s axon and another neurons dendrites.

How does the nervous system interpret incoming information? Scenario: Someone taps you on the shoulder Receptors in the skin sense a tap on the shoulder. Sensory neurons transmit the touch message. The message is interpreted. a response is sent to the motor neurons. Motor neurons transmit a response to the shoulder muscle. The neck muscles are activated, causing the head to turn.

Central vs. Peripheral Nervous System Central: Made up of the brain & spinal cord. Brain --- controls most functions Spinal Cord --- Covered with nerve tissues that link the brain to most nerves. Peripheral: Made up of the nerves that branch out from the brain & spinal cord.

Peripheral Nervous System Divided into sensory division vs. motor division Somatic NS regulates activities that are under conscious control. For example movement of skeletal muscles, like lifting your finger or wiggling your toes.

Autonomic Nervous System Autonomic nervous system regulates activities that are automatic or involuntary. For example – if you are running, your autonomic NS speeds up your heart rate and blood flow, stimulates sweat glands, and slows down contractions in digestive system Autonomic NS is split into Sympathetic vs. Parasympathetic NS Sympathetic speeds up activities while the parasympathetic slows activities down.

Divisions of the Nervous System Central Nervous SystemPeripheral Nervous System Made of the brain and spinal cord Somatic NS Autonomic NS Regulates activities that are automatic Regulates activities under conscious control Parasympathetic – slows down activities Sympathetic – Speeds up activities

Brain Parts Cerebrum : Interprets input from the senses, controls movement of muscles, & carries out complex mental processes (learning, remembering, & making judgments)

 Cerebellum: Coordinates the actions of your muscles & helps keep balance.

 Medulla --- controls involuntary actions (automatic actions – don’t have to think about doing these).  Examples – breathing, heartbeat, blinking.

Spinal Cord & Nerves Spinal cord – links brain to nerves and supports your body. Spinal nerves --- Impulses travel to & from the CNS via these nerves. Controls responses.