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Elyza Vivar per.5 Nervous system - Coggle Diagram
Elyza Vivar per.5 Nervous system
Major functions of the nervous system
Sensory input- detects internal and external changes
Integration and processing
motor output
Thinking
movement
internal process of physiology
Major divisions and subdivisions of the nervous system (include all subdivisions of CNS
and PNS)
CNS- made up of brain and spinal cord and responsible for intergration of info and decision making
PNS- made up of cranial and spinal nerves, contains sensory (afferent) & motor (efferent) divisions
Sensory fibers connecting peripheral sensory receptors to the CNS
Somatic fibers connecting to skin and skeletal muscles
Autonomic fibers connecting to viscera
Tissues (structure & function of neurons and neuroglia)
Neuroglia
Acts as nerve glue, supports neurons, and do not generate or conduct nerve impulses
Astrocytes
-lie between blood vessels & neurons
Functions:
structural support and prevents entry of many substances
Microglia
-cells that functions as phagocytes for bacterial cells and cellular debris, and produce scar tissue in sites of injury
Oligodendrocytes
-form myelin sheath around axons in the brain and spinal cord
Ependymal cells
-produce CSF in CNS
Schwann Cells
-myelin-producing neuroglia of PNS
Satellite
- provide protective coating around cell bodies of neurons in the PNS
Neurons
Neuron contains cell body, tubular cytoplasm-filled dendrites, and a tubular cytoplasm- filled axon
cell body
(Soma)
contain organelles including nucleus
Dendrites conduct impulses toward the cell body (are short and branch
Axon conducts impulses away from the cell body
Only one axon in a neuron
Larger axon are enclosed by myelin sheath they are called myelinated fibers
Narrow gaps in myelin sheath are called nodes of Ranvier
Myelin sheath increases conduction speed of nerve impulses
Classification of neurons
Structural classification
Multipolar nuerons
-have many dendrites & one axon arising from their cell bodies
Bipolar neurons
-Have 2 processes extending from the cell body ( a dendrite and axon)
Functional Classification
Sensory (afferent) neurons
-conducts impulses from peripheral receptors to the CNS
Interneurons (association or internuncial neurons)
-Multipolar neurons lying within the CNS that form links between other neurons
Motor (efferent) neuron
-Multipolor neurons that conduct impulses from the CNS to muscles or glands
Connective Tissue Coverings
Longer axons are enclosed by
myelin sheaths
axon is surrounded by
endoneurium
The entire nerve is enclosed by
epineurium
A bundle of fiber is fascicles fascicle which is enclosed by
perineurium
Major parts and functions of the brain
4 Main parts of the brain
Cerebrum
-largest portion of the brain: associated with higher mental functions
Diencephalon
-Inner part of cerebrum: processes sensory input and controls homeostatic processes
Cerebellum
-smaller back portion of the brain: coordinates muscular activity
Brainstem
- attached to cerrebelum: coordinates and regulates visceral act
Major parts and functions of the spinal cord
Motor Functions - directs your body's voluntary muscle movements.
Sensory Functions – monitors sensation of touch, pressure, temperature and pain.
Autonomic Functions – regulates digestion, urination, body temperature, heart rate, and dilation/contraction of blood vessels
Action potential & the Nerve Impulse
Threshold stimulus
:Stimulus strong enough to cause so many Na + ions to enter
Depolarization
-change from negative to positive change inside neuron
Repolarization
-returns to polarized state
Hyperpolarization
_A slight overshoot after repolarization
An action potential at trigger zone causes an electrical currents to flow to adjacent regions of the axons membrane
Refractory period
-period during & after an action potential, during which a threshold stimulus will not cause another action potential
Limits frequency of action potentials
Ensures the impulse is only transmitted in one direction down the axon
Cranial nerves
12 pairs of cranial nerves
Olfactory
- sense of smell
Optic
-sense of vision
Oculomotor
-conducts impulses to muscles that move eyelids
Trochlear
-conducts impulses to muscles that move eyes
Trigeminal
ophthalmic division-conducts impulses from eyes, tear glands, scalp, and forehead
Abducens
-conducts impulses to muscles that move eyes
Facial
-conducts impulses associated with taste receptors
Vestibulocochlear
-conducts impulses associated with the sense of equilibrium
Glossopharayngeal
-conduct impulses from pharynx and tonsils
Vagus
-Associated with speech and swallowing
11.
Accessory
-conducts muscles essential to neck and shoulder movement
Hypoglossal
-conducts to muscles that move the tongue
Spinal nerves
31 pairs of Spinal nerves
8 pairs
of cervical nerves
12 pairs
of thoracic nerves
5 pairs
of sacral nerves
5 pairs
of lumbar nerves
1 pair
of coccygeal nerves
Neurotransmitters
More than 100 neurotransmitters
Acetylcholine-located in
CNS and PNS
Controls skeletal muscles, stimulates contractions at neuronmuscular junctions, and may excite autonomic system
Norepinephrine-located in
CNS and PNS
Makes people happy, may excite autonomic nervous system
Dopamine-located in
CNS and PNS
Makes people feel good,limited actions in autonomic nervous system
Serotonin-Located in
CNS
leads to sleepiness,is blocked by LSD, and can be enhanced with selective serotonin inhibitor drugs
Histamine-located in
CNS
Release in hypothalamus and promotes alertness
Compare & contrast the autonomic nervous system
CNS is involuntary while PNS in voluntary
Reflex arc (major parts & functions)
Receptor
-senses internal and external changes
Sensory neuron
-carries info from receptor into brain or spinal cord
Inter neuron
-carries info from sensory neuron to motor neuron
Motor neuron
-carries instructions from brain or spinal cord out to effector
Effector
-responds to stimulation by motor neuron and produces reflex or behavioral action