1. -Human Nervous System-
Central Nervous System
Brain + Spinal Cord
Peripheral Nervous System
Nerves (extensions from the CNS)
Provides Basis For Conscious Experience

2. -Peripheral Nervous System-
Afferent
Efferent
Skeletal/Somatic - controls voluntary
movements of skeletal muscles
Autonomic - self-regulating, controls glands
& muscles of internal organs (e.g., heart)
Sympathetic
(arousing)
Parasympathetic
(calming)

3. -Central Nervous System- (billions of neurons & trillions of connections)
Spinal Cord
Conduit between peripheral nervous system
and the brain
Organizes certain behaviors without the brain
Conduit Function
- Ascending tract carries sensory info. to the brain
- Descending tract carries info from brain to muscles
Organization Function
- Governs reflexive actions of muscles

4. -Organization of the Nervous System-
Central
Nervous System
Peripheral
Nervous System
Brain
Spinal Cord
Somatic/
Skeletal
Autonomic

5. -Skeletal/Somatic Nervous System-
Nerves that connect to voluntary
skeletal muscles and to sensory receptors
Afferent Nerve Fibers
Axons that carry info away from the
periphery to the CNS
Efferent Nerve Fibers
Axons that carry info from
the CNS outward to the periphery

6. -Autonomic Nervous System-
Nerves that connect to the heart,
blood vessels, smooth muscles and glands
Sympathetic Division
Mobilizes the body’s resources
for emergencies (e.g., stimulate adrenal gland)
Fight or
Flight
Response
Cannon (1932)
Parasympathetic Division
Generally conserves bodily resources
(e.g., slows heart rate)

8. -The Nervous System- Peripheral Nervous System (PNS)
Made up of axons and dendrites.
It send messages to and from the CNS.
Central Nervous System (CNS) – brain and spinal cord directs mental and basic life processes.
Autonomic Nervous System (ANS)
Involuntary serves our basic life functions.
Somatic Nervous System (SNS) (Voluntary) sends sensory info to the CNS and motor messages to the muscles.
Sympathetic Nervous System
Readies the body for a threat
Parasympathetic Nervous System
Calms the body down and maintains energy

9. -The Neuron-
Neurons are the individual cells that transfer information throughout the body.
The Dendrites receive the input from other neurons and sensory receptors.
Cell Body (Soma) collects the information and sends it down the axon.
The Myelin Sheath covers the axon and helps speed up the message.
Bouton releases neurotransmitters into the synapse.
*Glial cells provide structural and nutritional support to the neuron.

10. -Different Types of Neurons-
Sensory Neurons send info. from the body tissues to the brain.
Motor Neurons take info from the brain and send it to the tissues.
Inter-neurons are our internal highway (brain and spinal chord).

11. -Neural Communication-
Sensory Neurons (few million)
Interneurons (100 billion)
Motor Neurons (few million)

12. -Neural Transmission-
Action Potential – neural impulses or messages.
Ions – chemicals inside and outside the axon/myelin.
Resting = Polarized. The fluid outside has more positively charged ions.
Action potential creates depolarization of the membrane Negative charge inside becomes positive.
Refractory periods occur after each action potential.

13. -Nerve Impulses- more (+) less (+) Intracellular Extracellular
Protein Molecules (A-) Sodium Ions (Na+)
Potassium Ions (K+) Chloride Ions (Cl-)
- Electrical signal is “Wet”.
- Signal travels via the flow of charged molecules, called “Ions”
- Nerve impulse is caused by a change in the nerve fiber’s PERMEABILITY to Na+ and K+.
- Permeability - the ease with which ions can pass through fiber membrane.
- At Resting Potential, the axon has a LOW PERMEABILITY to Na+.

14. -Nerve Impulses- Action Potential ...a brief electrical charge
1. Depolarization - Na+ channel open, Na+ rushes in
...a brief electrical
charge
traveling down
the axon,
like a line of
dominos
Depolarization (Steps 1 & 2) take 1/2000th second.
Repolarization (Steps 3 & 4) take an additional 1/2000th second.
(1 msec)
Each De/Re is called an ACTION POTENTIAL.
Each AP takes occurs at successive points along the axon (e.g., dominos).
“Traveling Nerve Impulse” is created by the flow of ions across the membrane.

15. -Properties of Nerve Impulses-
Once an A.P. is initiated, it travels down the length of the axon without stopping or changing size
All or nothing response

16. -Additional Properties-
Speed of AP determined by:
Axon Diameter (­ diameter = ¯ resistance)
Myelin Sheath (­ myelin = ­ speed)
Spontaneous Activity plays a role in perception.
Each neuron is completely separate from other neurons - no physical connections.
Approx 200 mph!

17. -The Synapse- Santiago Ramón y Cajal
Synapse is the space between the terminal ending (bouton/foot) of the sending neuron and the dendrites of the receiving neuron.
A chemical process bridges the gap between neurons.
Santiago
Ramón y
Cajal

18. -Neural Transmission-
The Synapse – the gap between the neurons
Terminal buttons release neurotransmitters that attach to the membrane of an adjacent neuron
Neurotransmitters can be excitatory or inhibitory
Terminal Button
Synapse
Presynaptic neuron – sends message
Postsynaptic neuron – receives message

20. -The Synapse-
1. Nerve impulse reaches Synaptic Vesicles in Terminal Button
2. Synaptic Vesicles release Neurotransmitters
- Neurotransmitters are picked up by next cell body and cause (maybe) a new AP to occur.
Excitatory neurotransmitters raise resting potential above -70mV.
(closer to threshold - more likely to fire)
Inhibitory neurotransmitters lower resting potential below -70mV.
(further from threshold - less likely to fire)
3. Neurotransmitters are Excitatory or Inhibitory

21. -Effects of Neurotransmitters-
Approx
15,000
Synapses
per
Neuron
- Brain neurons receive inputs from approx. 1 thousand other neurons.
If the sum of inhibitory or excitatory transmitters is greater than the threshold è IMPULSE OCCURS!

22. -Neurotransmitters & Behavior-
75 substances are clearly neurotransmitters
Other chemicals may serve a similar function
Specific neurotransmitters work at specific kinds of synapses
Agonists – excite or mimic neuro.
Antagonist – inhibit by blocking neuro.
Lock & Key

23. -Acetycholine (ACh)- ACh Motor Neurons Curare and the Black Widow
ACh’s primary function is in voluntary muscle movement.
It also contributes to:
attention, arousal
& memory processes
Motor Neurons
Voluntary Muscles
ACh
Curare
and the
Black Widow

24. -Biogenic Amines- Regulate aspects of everyday behavior Dopamine
Emotions,
attention, learning,
movement
Degeneration of
DA neurons
causes
Parkinson’s
Serotonin
Regulation of
mood, sleep,
hunger & arousal
Undersupply
of SR linked
to depression
Norepinepherine
Mediates alertness &
arousal levels
Low levels
of NE can depress mood

25. -Endorphins- (a.k.a. Endogenous Morphines) Endorphins Neuromodulators
Entire family of internally produced chemicals
that resemble opiates in structure and effects
Cross Blood-Brain Barrier
and bind to specialized
receptors in the brain
Neuromodulators
Chemicals that modulate activity of specific N.Ts
(e.g., Decrease N.T. that delivers pain signals)

26. -Endocrine System-
Endocrine (ducts) – release of hormones in the blood
Hormones move more slowly than neurotransmitters, but last longer
Effect growth, reproduction, metabolism, mood
Increase heart rate, blood pressure
Adrenal Gland
Release hormone (adrenaline)
Increased energy

27. -Endocrine System- Hypothalamus – control center
Anterior pituitary – growth hormone
Posterior pituitary – raises blood pressure
Thyroid (thyroxin) – increases metabolic rate, growth
Parathyroid – increases blood calcium, decreases potassium
Pancreas (insulin, glucagons) – regulates level of sugar
Ovary (estrogen) – promotes ovulation and sex characteristics
Testes (androgen)– promote sperm production and male sex characteristics