1. The Nervous System
Chapters 10 &11

2. BASIC IDEAS: ANATOMY PHYSIOLOGY STRUCTURE OF A NEURON
TYPES OF NEUROGLIAL CELLS
BRAIN STRUCTURE
CEREBRUM
CEREBELLUM
BRAIN STEM
PHYSIOLOGY
CONDUCTION OF NERVE IMPULSE
REFLEXES
SPECIFIC FUNCTIONS OF THE BRAIN

3. General Overview: Function: Maintain Homeostasis
Sensory Information
Perception and Integration
Motor responses
Structure: Neurons and Neuroglial Cells
Neurons classified by function (sensory, inter- and motor neurons) OR by structure (unipolar, bipolar, and multipolar)
Nerves – collections of neurons
Systems: Central Nervous System (brain and spinal cord) & Peripheral Nervous System (motor and sensory nerves)
Autonomic – involuntary Nervous System
Sympathetic – danger
Parasympathetic - Peaceful

4. Structure of a Neuron Cell Body – cell processes
Endoplasmic reticulum and golgi bodies (neurotransmitter production)
Nissl Bodies – groups of ribosomes
Cytoskeleton  shape
Dendrites – receptive surfaces
Axon – conducts nerve impulse (action potential)
Axon hillock
Axon terminals & Synapse
Schwann Cells
Myelin
Nodes of Ranvier

5. Neuroglial Cells Def. – accessory cells of the nervous system Types
Schwann cells – form myelin sheath around axons of PNS
Astrocytes - star shaped; structural support, nourishment, communication, clean-up
Oligodendrocytes – form myelin in CNS
Microglia – phagocytosis
Ependyma – porous barrier between fluid of brain/spinal cord neurons and cerbrospinal fluid
Regeneration of Nerve fibers
Injury to cell body, usually kills nerve cell
Injury to axon, axon can usually regenerate itself
Nerve growth factors and Glial cells help direct growth
CNS less likely to regenerate than PNS

6. Nerve Impulse
Key idea: nerves communicate with each other and effectors (muscles and glands) by sending an “action potential” down the axon, which cause a release of neurotransmitters into the synapse
Action Potential – nerve impulse
Series of changes in the neuron membrane which cause charged ions to flow in and out of the neuron

7. Establishing a Resting Potential
Potential difference (voltage) – difference in electrical charges between two places
Unequal distribution of positive and negative ions inside and outside of the neuron creates a small voltage
Resting Potential – normal voltage when neuron is not sending a signal
-70mV
Sodium-potassium pump moves Na+ ions out and K+ ions in
Potassium diffuses out of the cell faster than sodium diffuses in  more positive charges outside the cell
Negative ions are trapped inside the cell

8. Conduction of a Nerve Impulse
Creating an Action Potential
Dendrites or cell body react to stimuli
Different stimuli for different types of neurons
Temperature, light, pressure, chemical mechanical
Stimuli causes changes in the cell membrane
Gates open allowing movements of ions
Depolarization – change from -70 to +30 mV
Sodium ions rush in
This change in voltage causes the next part of the neuron to do the same
Works like dominos
Repolarization – return to resting potential
repolarization causes K+ channels to open and potassium rushes out

9. Actions at the Synapse
Synapse – the space between the axon terminal of one neuron and 1) the dendrites of the next neuron OR 2) an effector
Effectors are muscles or glands
Events:
Action potential reaches synaptic knob
Ca++ to rush in
Exocytosis of neurotransmitter
Vesicles reenter and refill
Examples of Neurotransmitters
Acetylcholine, dopamine, epinephrine, norepinephrin, serotonin

10. Conduction of a Nerve Impulse
Speed of nerve impulses
Refractory period – time in which a neuron cannot be stimulated again
About 1 impulse per millisecond
Saltatory Conduction – nerve impulses on myelinated neurons
Faster than unmyelinated
Action potentials jump between Nodes of Ranvier
Greater the diameter of nerve fiber, the faster the nerve impulse

11. Odds and Ends
Control of neurotransmitters: inhibitory and excitatory post-synaptic potentials
Impulse Processing
Neuronal pools
Facilitation
Convergence vs. Divergence
Nerve fiber classification
General vs. Special
Somatic vs. visceral
Afferent vs. Efferent

12. Reflexes
Def: a subconscious action that automatically respond to stimuli
Receptor  Sensory neuron  interneuron  motor neuron effector
Breath rate, heart rate, and blood pressure are controlled by reflexes
Examples
Knee-Jerk – helps to keep posture by contracting the quadriceps if tendon becomes stretched
Simple  one sensory neuron and one motor neuron
Other common reflexes: ankle-jerk, biceps-jerk, triceps-jerk, plantar
Babinski reflex – toes spread apart; normal in babies (under 1)
Withdrawal Reflex – contraction of biceps when finger touches something hot/sharp
Reduces tissue damage
Biceps contract; triceps relax
Crossed extensor reflex – opposite side does opposite action

13. Structure of the Nervous System
Phineas Gauge – 1st brain study
CNS – Brain + Spinal Cord
Meninges – coverings
Dura Mater
Arachnoid Mater
Pia Mater
Cerebrospinal Fluid
Real Life Applications: Subdural Hematoma, Epidural, Meningitis, Hydroencephaly (hydrocephalus)
Spinal Cord
White and Gray Matter
Ascending and Descending Nerve Tracts

14. The Brain Parts: Cerebrum Cerebellum Brain Stem
Perception and higher level thinking
Hemispheres
Lobes
Convulutions
Cerebellum
Arbor Vitae
coordination
Brain Stem
Medulla oblongata, pons and midbrain
Vital functions