Download three basic functions of the nervous system

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.
Nervous System
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
Sensation?
Integration?
Response?
Create your
own example
with a partner
The Neuron
Neurons = masses of nerve
cells that transmit information
1. Cell Body - contains the nucleus
and two extensions
2. Dendrites – shorter, more
numerous, receive information
3. Axons – single, long “fiber” which
conducts impulse away from the
cell body, send information
Types of Neurons (Functional)
1. Sensory neurons – transmit impulses to the spinal cord
and brain from all parts of the body
- also called afferent neurons
2. 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
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
Microglia
Oligodendrocyte
Schwann Cell
Astrocyte
Description
Location
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
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/wat
ch?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