Nervous System

Nervous System

Central vs. Peripheral Nervous System 

1. Central Nervous System (CNS): brain and spinal cord

Central vs. Peripheral Nervous System 

2. Peripheral Nervous System (PNS): cranial nerves, spinal nerves and ganglia 

* (Ganglion=group of neuron cell bodies located outside CNS)

Sensory division vs. Motor division 

1. Sensory Division: receives information FROM body and transmits it TO the CNS for processing 

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a) Somatic Sensory component – receives sensory information from skin, joints, muscle, special senses b) Visceral Sensory component – receives sensory info from blood vessels and viscera

2. Motor Division: transmits info FROM the CNS TO muscles and glands  

a. Somatic motor component: innervates skeletal muscle b. Autonomic motor (Autonomic Nervous System): innervates smooth muscle, cardiac muscle, and glands of viscera (organs)

NERVOUS TISSUE CELLS 

A. Neurons: respond to stimuli and conduct nerve impulses

NERVOUS TISSUE CELLS 

B. Glial Cells: support and protect neurons (maintenance)

NEURON COMPOSITION (p 104) 

A. Cell Body:

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B. Nucleus:

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C. Dendrites:

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D. Axon:

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E. Synapse:

NEURON CLASSIFICATION 

1. Sensory (Afferent) Neuron: brings information TO the CNS

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2. Motor (Efferent) Neuron: takes information FROM CNS to other parts of the body, cell body located in CNS

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3. Interneuron (Association Neurons): helps coordinate and integrate info between sensory and motor neurons, cell body located in CNS

GLIAL CELLS - PNS 

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A. Satellite Cells: surround neuron cell bodies in spinal ganglia * (Ganglion=group of neuron cell bodies located outside CNS) B. Schwann cells: myelinate axons in PNS

Glial Cells - CNS 

C. Astrocytes: regulate transfer of materials from blood to the brain - help the workings of "blood -brain barrier"

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D. Oligodendrocytes: myelinate axons in CNS

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E. Microglia: phagocytize damaged neurons

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F. Ependymal Cells: line central canal and ventricles help circulate cerebrospinal fluid (CSF)

MYELINATION OF AXONS 

wrapping an axon with myelin

The Brain 

4 Regions 

Cerebrum 

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R & L Hemispheres

Diencephalon Brain Stem Cerebellum

Brain – Cerebrum  

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Largest Region Gyri (twisters) & Sulcus (grooves) Fissures (deep grooves) 

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Longitudinal (hemispheres) Divide Lobes

Brain – Cerebrum (lobes) 

Parietal Lobe  

Somatic sensory area “homunculus”

Brain – Cerebrum (lobes) 

Occipital Lobe 

Visual area

Brain – Cerebrum (lobes) 

Temporal Lobe 

Olfactory 

Deep inside

Brain – Cerebrum (lobes) 

Frontal Lobe   

Primary Motor Area Speech Language

Cerebrum 

Cerebral Gray Matter (Cortex) 

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Cerebral White Matter 

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superficial deeper

Corpus Callosum 

connects hemispheres

Diencephalon (interbrain)   

Sits atop brain stem Enclosed by cerebrum Structures   

Thalamus Hypothalamus Epithalamus

Diencephalon 

Thalamus 

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Relay station from spinal cord Crude impulse 

Pleasant vs. Unpleasant

Diencephalon 

Hypothalmus (“under the thalmus”) 

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ANS (Emotional Visceral Brain) Body Temp, H2O balance, Metabolism Appetites (thirst, hunger) Pleasure & Pain

Diencephalon 

Epithalamus 

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Pineal body (endocrine system) Choroid plexus (cerebrospinal fluid)

Brain Stem  

About size of thumb Areas 

Midbrain 

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Pons 

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Convey impulses Controls breathing

Medulla Oblongata 

Heart rate, BP, Swallowing, Vomiting, etc.

Cerebellum  

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Convoluted surface Precise timing of Skeletal muscles Balance “Auto-Pilot”

Protection of Brain 

Meninges 

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Cerebrospinal Fluid 

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dura mater (tough mother) arachnoid mater pia mater (gentle mother) Eliminate waste

Blood-Brain Barrier 

Least-permeable membrane in body

Spinal Cord  

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Aprox. 17 in long Continuation of Brain Stem Ends Below ribs

Spinal Cord 

Gray Matter  

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CSF 

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Posterior Horns (dorsal) Anterior Horns (ventral) Central Canal

Protection    

Vertebrae Dura mater Arachnoid Pia mater

Spinal Cord     

Cervical Thoracic Lumbar Sacral Coccygeal

Spinal Cord - Cervical 

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8 Cervical Nerves C1C8 Diaphragm, Shoulders, Neck Damage may result in: 

Respiratory Paralysis

Spinal Cord - Thoracic  

T1-T12 Intercostal

Spinal Cord - Lumbar  

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L1-L5 Lower abdomen, buttocks, anterior & medial thigh, hip muscles, skin of thigh Damage:  

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Inability to flex hip Loss of cutaneous sensation Inability to adduct thigh

Spinal Cord – Sacral & Coccygeal 

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S1-S5 + Coccygeal Nerve Lateral & posterior leg/foot, gluteus, lower trunk Damage:  

Inability to extend hip Inability to flex knee