1. Structure and Function of the Nervous System

2. Peripheral Nervous System:
Cranial nerves (12 pairs)
Spinal nerves (31 pairs)
Afferent (ascending) – sensory
Efferent (descending) – motor
Central Nervous System:
Brain
Spinal cord

3. Central Nervous System

6. Peripheral Nervous System
Somatic Nervous Autonomic Nervous System System
Operates with conscious control              Usually without conscious control Controls skeletal muscle Regulates body’s internal
environment
Releases Acetylcholine at synapses               Releases
acetylcholine or
norepinephrine at
                                                                           synapses

7. Autonomic Nervous System
Sympathetic Parasympathetic Nervous System Nervous System
Originates in the thoracic Originates in the brain stem
and lumbar segments         (cranial nerves) and sacral
of the spinal cord : segments of the spinal Thoracolumbar system cord: Craniosacral system

8. Sympathetic Parasympathetic Nervous System Nervous System
Effect is wide spread            Effect is local
"Fight-or-Flight" - Bear           "Feed and Breed” - Book emergency, excitement, exercise,            salivation, lacrimation, urination,
  embarrassment defecation                                                                                      
Postganglionic fibers Postganglionic fibers release norepinephrine     release Ach
Preganglionic fibers of both release ACh

9. Cells of the Nervous System
Neurons – the primary cell of the nervous system
Supporting cells – Neuroglial cells

10. Neurons Each neuron is adapted for a specialized function.
Detect environmental changes
Process information
Initiate body responses
Fuel source is mostly glucose

14. Saltatory conduction

16. Neuroglia – “Nerve glue”
Schwann cells form the myelin sheathes of axons in the peripheral nervous system. Astrocytes Oligodendrocytes Microglia Ependymal cells are found in the CNS

21. Generation of nerve impulses
Action potentials are generated when stimulus is greater than threshold.
Action potential is an all-or-none response
Axon has a resting potential
Opening of voltage gated channels propagates current down axon
At end of axon, neurotransmitters released from synaptic knobs into synaptic cleft

28. Neurons interact with other neurons
Synapse – region between two neurons
Presynaptic → Postsynaptic
Neurotransmitters:
Excitatory – Excitatory postsynaptic potentials (depolarize)
Inhibitory – Inhibitory postsynaptic potentials (hyperpolarize –more difficult to reach threshold)

29. Neurotransmitters At least 30 known Acetylcholine Amino acids – GABA
Biogenic amines – catecholamines – norepinephrine, epinephrine, dopamine
Also serotonin and histamine
Neuropeptides – opiates such as enkephalins and endorphins
Gases – Nitric oxide (NO)- vasodilation

31. Brain

32. Divisions of Brain
Forebrain - cerebral hemispheres, thalamus and hypothalamus
Midbrain - corpora quadrigemina and cerebral peduncles
Hindbrain - cerebellum, pons, medulla oblongata
Reticular formation
Reticular activating system

40. Gyri - convolutions
Sulci - grooves
Gray matter – nerve cell bodies and dendrites (unmyelinated)
White matter – myelinated axons

41. Spinal cord Lies in vertebral canal protected by vertebral column
Connects brain and body
Somatic and autonomic reflexes
Begins at medulla oblongata and ends at conus medullaris at L1 or L2

49. Protective Structures
Cranium
Meninges:
Dura Mater – “Tough mother”
Periosteum and meningeal layer
Falx cerebri, Falx cerebelli, and Tentorium cerebelli
Arachnoid – “Spider web-like”
Subarachnoid space – CSF flows
Pia mater – “Gentle mother”

60. Blood-Brain Barrier Capillaries have tight junctions
Aided by astrocytes
Selectively permeable
Important when we want to get antibiotics or other chemotherapeutic agents into the brain.