1. The Nervous System 18.1

2. Nervous System
Nervous System -the body system of an organism that gathers, processes and responds to information.
Receives info from 5 senses: vision, hearing, smell, taste, and touch.
It can receive information, process it, and respond in less than one second.

3. Nervous System Functions
1. Gathering information and interpreting that information. Stimulus – a change in an organism’s environment that causes a reaction.
2. Responding to Stimuli- reacting are ways that the nervous system enables people to respond to the environment.
3. Maintaining Homeostasis- by regulating the internal environment as a response to the stimuli. Ex. Heart and breathing increase.

4. Neurons
Also called nerve cells, are the basic functioning unit of the nervous system.
Help with communication with different body parts.
3 parts of a neuron:
1. Dendrite – receives info
2. Cell Body – processes the info
3. Axon – sends the info.

6. 3 Types of Neurons
Sensory Neurons –send info about the environment to your brain or spinal cord.
Motor Neurons – sends info from brain to body parts
Interneurons – connect sensory and motor neurons

7. Central Nervous System
Has 2 parts: brain and spinal cord.
CNS receives, processes, stores and transfers information.
Brain receives info, processes it and sends out a response, stores info as memories.
Cerebrum – part of the brain that controls, memory, language, and thought. Largest and most complex part of the brain.
Cerebellum – coordinates voluntary muscle movement and regulates balance and posture.
Brain Stem – controls involuntary functions. Connects brain to spinal cord.
Spinal cord – tubelike structure of neurons. Sends info to and from brain

9. Peripheral Nervous System
Nervous system is made of the CNS and PNS (peripheral nervous system).
PNS – sensory neurons and motor neurons that transmit information to the CNS and rest of the body.
2 parts:
1. Somatic System – controls skeletal muscles
2. Autonomic System – controls smooth muscles and cardiac muscles.

11. Nervous System Health Necessary for maintaining homeostasis
Most damage is due to physical injuries.
Paralysis can occur
Reflex –automatic response to a stimulus.
Reflexes protect us from harm.
Drugs affect the nervous system (speeding up or slowing down).
Depressant –drug that slows down communication between neurons.
Stimulant – speeds up the communication between neurons.

12. Nervous System & Homeostasis
The nervous system sends signals to the other body systems to make adjustments to the external environment.
By receiving, processing and responding to information from the environment helps maintain homeostasis.
Sensing any changes and allowing adjustments.