CHAPTER 8: NERVOUS SYSTEM

SIM - SENSORY, INTEGRATION, MOTOR

3 MAJOR FUNCTIONS

● Maintaining homeostasis

● Receiving sensory input

● Integrating information

● Controlling muscles and glands

● Establishing and maintaining mental activity

FUNCTIONS OF THE NERVOUS SYSTEM

Central Nervous System (CNS), Peripheral Nervous System (PNS)

2 ANATOMICAL DIVISIONS

Central Nervous System (CNS)

a. Spinal cord

b. Brain

Peripheral Nervous System (PNS)

All the neural tissue outside the CNS (spinal nerves, cranial nerves)

Afferrent Division, Efferent Division

2 SUBDIVISIONS

afferent division

sensory input (pasok)

efferent division

sensory output (labas)

SNS, ANS - somatic nervous system and autonomic nervous system

two types of efferent division

SD, PD - sympathetic division, parasympathetic division

Autonomic nervous system two types

sympathetic division

most active during physical activity

parasympathetic division

regulates resting functions

Somatic sensory

anything outside/external

Visceral sensory

internal

neurons, neuroglia

CELLS OF THE NERVOUS SYSTEM

neurons (nerve cells)

For processing, transfer, and storage of information

neuroglia (supportive cells)

For support, regulation, and protection of neurons

GLIA = glue

neurons

Receive stimuli transmit action potentials to other neurons or to effector organs

CAD - cell body, axon, dendrites

3 parts of neurons

neurons

Organized Network - Performs the function of the nervous system

dendrites

Stimulated by the environmental changes of the activities of other cells

cell body

Contains the nucleus, mitochondria, ribosomes, and other organelles and inclusions

axon

Conducts nerve impulse (action potential) toward synaptic terminals

synaptic gland

Affect another neuron or effector organ (muscle or gland)

Nissl Bodies

Neurofilaments separate abundant rough ER

i. Primary site of protein synthesis in neurons

DENDRITES

Short , Often highly branched cytoplasmic extensions

Dendrite Spines

Small extensions where axons of other neurons form synapses with the dendrites

axons

Nerve fiber, Conducts electrical impulses away from the neuron’s cell body

(MA,BP) - multipolar, anaxonix, bipolar, pseudo-unipolar nueron

STRUCTURAL TYPES OF NEURONS

multipolar neurons

Many dendrites, Single axon and Most common type

anaxonic neurons

No axon and no anatomical clues to determine axons from dendrites

bipolar neuron

One dendrite, One axon

pseudo-unipolar neurons

An axon, No dendrites, Single process extending from the cell body

SMI - sensory neurons, motor neurons, interneurons

FUNCTIONAL TYPES OF NEURONS

sensory neurons (afferent neurons)

Conducts action potential toward the CNS

interneurons

Conducts action potential from one neuron to another within the CNS

motor neurons (efferent neurons)

Conducts action potential away from the CNS toward muscles or glands

CNS NEUROGLIA, PNS NEUROGLIA

NEUROGLIA (GLIAL CELLS)

AMOE - astrocytes, microglia, oligodendrocytes, ependymal cells

CNS NEUROGLIA:

SS - schwann cells (neurolemmocytes), satellite cells

PNS NEUROGLIA:

schwann cells

Wraps around axons

myelin sheath

■ Insulating layer

■ Forms around nerves

satellite cells

• Surround neuron cell bodies in sensory and autonomic ganglia

• Protect neurons from heavy-metal poisons

astrocytes

Star look-alike and Creates a supportive framework for neurons

EPENDYMAL CELLS

○ Lines ventricles of brain & central canal of spinal cord

○ Produce, monitor, and help circulate CSF (cerebrospinal fluid)

microglia

○ Brain macrophages

○ Phagocytize cellular wastes & pathogens

○ Cell-eating

astrocytes

Creates “blood-brain barrier” BBB and monitor & regulates interstitial fluid

surrounding neurons

OLIGODENDROCYTES

Cytoplasmic extensions that can surround axons

myelin sheath

Most axons of the nervous system are surrounded by a ___ (myelinated axon)

“white matter."

Regions of the nervous system containing groupings of myelinated axons make up the ___

gray matter

mainly comprised of groups of neuron cell bodies, dendrites, and synapses (connections between neurons)

myelin sheaths

Presence of myelin speeds up the transmission of action potentials along the axons

Nodes of Ranvier

spaces/gaps

Gray Matter

Consists of groups of neuron cell bodies and their dendrites

White Matter

Consists of bundles of parallel axons with their myelin sheaths

synapse

Site at which neurons communicate

pp = presynaptic neuron, postsynaptic neuron

type of cells in synapse

presynaptic neuron

Conducts impulse toward the synapse

postsynaptic neuron

Conducts impulse away from the synapse

electrical synapse, chemical synapse

TWO MAJOR TYPES OF SYNAPSE

Electrical Synapse

Not common in the nervous system

Chemical Synapse

Most common type due to many neurotransmitters

psp = presynaptic terminal, synaptic cleft, postsynaptic membrane

components of Chemical Synapse

Synaptic vesicles, Diffusion, Postsynaptic membrane

Neurotransmitters release by action potential in presynaptic terminals