1. THE NERVOUS SYSTEM pp

2. FUNCTION
Network of cells (neurons) that communicate and control the body through electrical impulses (fast) versus chemicals in the endocrine system (slower)
Includes neurons (cells that carry messages), brain and spinal cord

3. CENTRAL NERVOUS SYSTEM CNS
Brain – control center with different sections controlling different parts of the body
Spinal cord – column of nerve tissue that acts as a communication link between brain and Peripheral NS.

6. PERIPHERAL NERVOUS SYSTEM PNS
Carries impulses to and from the CNS.
Motor division (reacts to sensory input)
1. Somatic nervous system (voluntary): transmits impulses to and from skeletal muscle (including reflexes)

7. 2. Autonomic nervous system (involuntary) – controls glands, internal organs, and other smooth muscle tissue (EX. Parasympathetic and sympathetic response to acute stress)

9. REFLEXES
Sensory information does not need to be processed by the brain
During a reflex the information is processed in the spinal cord

10. NEURONS

11. Axons: extension away from the cell body
Axon terminal: end of the axon
Dendrites: Receive action potentials (electrical impulse/message) from other neurons
Synapse: gap between neurons
Myelin sheath: lipid layer around axon (insulator)

12. NERVE IMPULSES

13. Think of the impulse as electrical and negative
The impulse (action potential) starts at the dendrites or the cell body and travels along the axon until the axon terminal

14. When the impulse reaches the end (axon terminal) neurotransmitters are released from the neuron, into the synapse, to receptors in the next cell (dendrite)

16. TYPES OF NEURONS
Sensory – sense organs/receptors send stimulus to brain to process.
Motor – sends response from brain to muscles/glands to react.
Interneurons – connect sensory and motor and carry impulses between them.

19. SENSORY NEURONS
Most people think that we have only five senses but your body maintains homeostasis with more than 25 different types of senses
Sensory neurons detect (sense) a stimulus to be processed by the central nervous system
Sensory neurons have specific shapes to do their job and some body functions require more than one type of sensory neuron (i.e. balance)

20. Pressure and Temperature
Mechanoreceptors and thermoreceptors, respectively

22. Vision Photoreceptors
2 types: cones (bright light) and rods (dim light)

24. Hearing and balance Mechanoreceptors
The neurons look like hair and move to the vibration of air (hearing) or movement of fluid (balance)

26. TASTE
SMELL

27. Taste and Smell
Chemoreceptors
Scent and taste are just chemicals

28. Tissue damage
Pain receptors (Nociceptor)