1. Central Nervous System (CNS) Peripheral Nervous System (PNS)
The Nervous System
Central Nervous System (CNS)
Peripheral Nervous System (PNS)

2. Do Now: Contract a K-W-L chart on loose-leaf
List everything you already Know about the Nervous System in the K-column
List everything you Want to know in W-column

3. Functions Monitors internal and external environments
Integrates sensory information
Coordinates voluntary and involuntary responses of other organ systems
2 subdivisions:
CNS – brain and spinal cord
Intelligence, memory, emotion
PNS – all other neural tissue
sensory, motor

4. Receptors and Effectors
Receptors – receive sensory info
Afferent division – carries info from sensory receptors to the CNS
Efferent division – carries info from CNS to PNS effectors (muscles, glands, adipose)
Somatic Nervous System (SNS)
Controls skeletal muscles (voluntary)
Autonomic Nervous System (ANS)
Controls involuntary actions
Sympathetic Division (increase heart rate)
Parasympathetic Division (decreases heart rate)

6. Neurons Communicate w/other neurons Soma-Cell body
Dendrites - receive info
Axon- sends signal to synaptic terminals (terminal buds)
Synapse – site of neural communication (gap)
Myelin – fatty insulation of axon(Schwann cells produce in PNS)
Node of Ranvier – exposed axon between myelin
3 structural types:
Multipolar – multiple dendrites & single axon (motor neurons)
Unipolar – continues dendrites & axon, cell body lies to side (sensory neurons)
Bipolar – one dendrite and one axon w/cell body between them (special senses)
White matter- myelinated fibers
Gray mater- unmyelinated

7. Types of Neurons 3 functional types Sensory – afferent division
info about surrounding environment
position/movement skeletal muscles
digestive, resp, cardiovasc, urinary, reprod, taste, and pain
Motor – efferent division (response)
skeletal muscles
cardiac and smooth muscle, glands, adipose tissue
Interneurons
Brain and spinal cord - memory, planning, and learning

8. Neuroglia Regulate environment around neurons; actively divide
Functions in CNS:
maintains the blood-brain barrier(Astrocytes)
create myelin (lipid) to coat axon(Oligodendrocytes)
Nodes of Ranvier – gaps between myelinated sections
Internodes – areas covered in myelin
Phagocytic cells(Microglia)

9. View Action Potential Remember:
Discuss each question and answer with your group
Use the information from the models to support your responses

10. Membrane Potential Cells are polarized (measured in volts)
Resting potential of neuron -70mV
Remains stable due to Na+/K+ Pumps
Leak channels – always open (K+ diffuses out) K+
Proteins-
Net - charge
Na+
Cl-
Gated channels – open/closed under specific circumstance

11. Changes in Membrane Potential
Depolarization
Stimulus opens Na+ gated channels
increase +charge of cell towards 0mV
Action Potentials
Affects entire surface of cell membrane
(+) feedback as nerve impulse continues
Hyperpolarization
Stimulus opens K+ gated channels
Increases –charge (from -70mV to -80mV)
Restores resting potential

12. Action Potential: All or Nothing Principal
Only skeletal muscle fibers and neuron axons have excitable membranes
Graded potential increases pressure until sufficient enough to reach action potential
Resting potential (-70mV)
Reaches Threshold (-60mV)
Refractory Period – cell cannot respond to stimulation
Depolarization
Repolarization
Continuous Propagation
chain rxn until reaches cell memb
Unmyleinated – 1m/s (2mph)
Salatory Propagation
Myelinated (blocks flow of ions except at nodes)
Action potential jumps from node to node
18-40m/s (30-300mph)

13. Neural Communication
Nerve impulse – info moving in the form of action potentials along axons
At end of axon the action potential transfers to another neuron or effector cell by release of neurotransmitters from synaptic terminal (only occur in 1 direction)
Activity of neuron depends on balance between:
Excitatory neurotransmitters - depolorization
ACh & Norepinephrine
Inhibitory neurotransmitters -hyperpolarization
Dopamine, Seratonin, GABA

14. Reflexes
Reflex – involuntary response to stimulus w/o requiring the brain
Reflex arc- sensory neuron Interneuron motor neuron (opposes initial stimulus)
Ex. Knee jerk reflex
Babinski reflex (infants only)
Stroke sole of foot  toes fan out
Plantar reflex (adults only)
Stroke sole of foot toes curl
Signals sent to brain by interneurons allow for control
Ex. Toilet training, gag, blink