Do Now 1/7/15 Welcome back – happy 2015! “Brain”storm: If you didn’t have a brain, what would you NOT be able to do? Write down at least 3 ideas.

Central Nervous System (CNS): brain and spinal cord. Peripheral Nervous System (PNS): nerves of the body         - 31 pairs of spinal nerves         - 12 pairs of cranial nerves

Basic Divisions of the Nervous System Figure 12.2

Motor Functions Somatic Nervous System - skeletal (voluntary) Autonomic Nervous System -  smooth muscles, glands (involuntary)

THREE BASIC FUNCTIONS OF THE NERVOUS SYSTEM Sensory -  receptors gathers info from stimuli Integration - information is brought together Motor - responds to signals, homeostasis

Create your own example with a partner Sensation? Integration? Response? Create your own example with a partner

The Neuron Neurons = masses of nerve cells that transmit information Cell Body - contains the nucleus and two extensions Dendrites – shorter, more numerous, receive information Axons – single, long “fiber” which conducts impulse away from the cell body, send information

Types of Neurons (Functional) Sensory neurons – transmit impulses to the spinal cord and brain from all parts of the body - also called afferent neurons Motor neurons – transmit impulses away from the spinal cord and brain to muscles and tissue - also called efferent neurons 3. Interneurons – conduct impulses from sensory neurons to motor neurons S.A.M.E. Sensory = Afferent Motor = Efferent

Neurons Classified by Function: Sensory vs. Motor Neurons Figure 12.11

Types of Neurons (Structural) Structural: (A) Bipolar (B) Unipolar (C) Multipolar Prefix related to number of extensions

Interesting Characteristics about the Neuron Longevity – can live and function for a lifetime Do not divide (Amitotic) – fetal neurons lose their ability to undergo mitosis; neural stem cells are an exception Excitability – neurons respond to stimulation Conductivity – electrical changes can travel through a neuron Secretion – neurotransmitters (NT) are released

glia means glue Neurons are not the only type of nervous cell Glial cells provide support for the neurons. glia means glue Behind every successful neuron is an “army” of even more awesome glial cells.

Type of Glial Cell Description Location Microglia Oligodendrocyte Schwann Cell Astrocyte

Glial Cells - support cells for the neurons   1.  Microglia: scattered throughout the CNS, digest debris or bacteria Microglial cells respond to immunological alarms

Glial Cells 2. Oligodendrocytes: makes the myelin sheath that provides insulation around the axons in the CNS

3.  Schwann cells:  form the insulating myelin sheath around the neurons in the PNS        

4. Astrocytes: connect blood vessels to neurons in the CNS I connect to blood vessels

Supporting Cells- NEUROGLIA

- these serve as insulation around the axon MYELIN SHEATHS - these serve as insulation around the axon Schwann cells supply the myelin for peripheral neurons, Oligodendrocytes myelinate the axons of the central nervous system.

Function of Myelin Sheaths Myelin allows the neuron to send impulses quicker The nerve fibers of newborns are unmyelinated - this causes their responses to stimuli to be course and sometimes involve the whole body.  Try surprising a baby! https://www.youtube.com/watch?v=N9oxmRT2YWw

White vs Grey Matter Myelinated (white matter) – myelinated axons Unmyelinated (grey matter) - unmyelinated

Additional structures of a neuron Myelin -insulation surrounding axons Nodes of Ranvier - gaps in the insulation Terminal buttons – the “buttons” at the end of the axon

The Synapse Synapse - junction between two communicating neurons   Nerve pathway - nerve impulse travels from neuron to neuron Dendrite → cell body → along axon -> synapse (gap) → dendrite

Labeling a Neuron Axon Axon Hillock Cell Body Dendrite Myelin Sheath Nodes of Ranvier Nucleus Synapse Terminal Buttons

Resting Membrane Potential -70 mV

Cell Membrane Potential