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Stephanie Hernandez Period 7 Nervous System - Coggle Diagram
Stephanie Hernandez Period 7
Nervous System
Compare & contrast the autonomic nervous system
Sympathetic division:
active in conditions of stress or
emergency (fight or flight).
There they synapse with postganglionic neurons, whose long axons return to spinal nerves and then proceed to a visceral effector. Sometimes, preganglionic fibers pass right through the paravertebral ganglia, and synapse in collateral ganglia, closer to the target organs.
Short preganglionic fibers in the sympathetic division arise from neurons in the gray matter in the thoracic and lumbar regions of the spinal cord. The axons then leave the spinal nerves, and proceed into the sympathetic (paravertebral) ganglia , a chain of sympathetic ganglia close to the vertebral column on each side.
Parasympathetic division
: active under normal, restful
conditions (rest and digest).
Long preganglionic fibers in the parasympathetic division arise from the brainstem and sacral region of the spinal cord. The preganglionic fibers extend outward in cranial or sacral nerves, and synapse in terminal ganglia close to or in visceral effector organs.
Short postganglionic fibers continue into the effector organs
(muscles or glands).
Major functions of the nervous system
Motor function
: Nerve impulses (CNS) are conducted along motor neurons to
effectors. Effectors are muscles or glands that respond to decisions made in the
CNS.
Integrative function
: Coordination of sensory information in the CNS. Processing of this information is the basis for decision-making.
Sensory function
: Provided by sensory receptors, which detect internal or external
changes. Information travels from receptors to sensory neurons, which
transport information into the CNS.
Spinal nerves
: 31 pairs of spinal nerves arise from the spinal cord. All except the first pair are mixed nerves. Numbered in sequence: 8 pairs of cervical nerves, 12 pairs of thoracic
nerves, 5 pairs of lumbar nerves, 5 pairs of sacral nerves, and 1 pair of coccygeal nerves.
Each arises from two roots
: a sensory dorsal root and a motor ventral
root A ventral root and dorsal root unite to form a spinal nerve, which
extends out of the vertebral canal through the intervertebral foramen.
Major parts and functions of the brain
Cerebellum
: coordinates muscular activity.
Diencephalon
: processes sensory input and controls many homeostatic
processes.
Cerebrum
: largest portion; associated with higher mental functions, and
sensory & motor functions.
Brainstem
: coordinates and regulates visceral activities, and connects
different parts of the nervous system.
Major divisions and subdivisions of the nervous system
Peripheral nervous system
Cranial nerves arising from the brain and brainstem
Automatic nervous system
: Autonomic fibers connecting to viscera
Somatic nervous system:
Connects CNS to skeletal muscle and skin, oversees conscious activities.
Sensory fibers connecting peripheral sensory receptors
to the CNS
Central nervous system
Spinal Cord
: The spinal cord is a long bundle of nerves and cells that extends from the lower portion of the brain to the lower back. It carries signals between the brain and the rest of the body.
Brain
: It is located in the head, usually close to the sensory organs for senses such as vision. It.
Classification of neurons
Motor (efferent) neurons:
multipolar neurons that conduct impulses from the CNS to peripheral effectors (muscles or glands).
Interneurons (association or internuncial neurons):
multipolar neurons lying within the e CNS that form links between other neurons; the cell bodies of some interneurons aggregate in specialized masses called nuclei.
Sensory (afferent) neurons:
conduct impulses from peripheral receptors to the CNS; usually unipolar, although some are bipolar.
Major parts and functions of the spinal cord
Lumbar enlargement
: A thickened region near the bottom of the spinal cord. Gives rise to nerves that serve the lower limbs.
Cauda equina (horse’s tail)
: Structure formed where spinal cord tapers to a point inferiorly. Consists of spinal nerves in the lumbar & sacral areas.
Cervical enlargement
: A thickened area near the top of the spinal cord. That provides nerves to the upper limbs.
Reflex Arc (major parts & functions)
Receptor
: Senses specific type of internal or
external change.
Sensory
neuron
: Carries information from receptor
into the brain or spinal cord.
Motor
neuron
: Carries instructions from brain or
spinal cord out to effector.
Interneuron
: Carries information from sensory
neuron to motor neuron.
Effector
: Responds to stimulation (or inhibition) by motor neuron and produces reflex or behavioral
action.
Cranial nerves
: Twelve pairs of cranial nerves arise from the underside of the
brain. Most are mixed nerves, containing sensory & motor nerve fibers,
but some are only sensory, and others are primarily motor. The first pair arises from the cerebrum, and the second pair from
the thalamus, but most arise from the brainstem.
Connective Tissue Coverings
Endoneurium
: covering around individual nerve fibers (axons).
Epineurium
: outer covering of a nerve
Perineurium
: covering around fascicles (bundles) of nerve fibers
Tissues
Neuroglia
: cells that support, nourish, protect, and insulate
neurons.
Neurons
: cells that communicate, via electrical impulses, with
other neurons or other tissues.
Action potential & the Nerve Impulse
Upon reaching threshold potential, voltage-gated Na+ channels open,
changing charge to about +30 mV; this is called an
action potential.
Reaching an action potential is all-or-none response. It occurs when the charge reaches -55 mV.
Action potentials
of a neuron are all of the same strength
A
nerve impulse
is the relaying of a coded signal from a nerve cell to an effector (a muscle cell, a gland cell, or another nerve cell) in response to a stimulus. This signal is relayed along the axon of the nerve cell, bringing a message that instructs an effector to act.
Neurotransmitters:
There are more than 100 neurotransmitters. Neurotransmitters include acetylcholine, amino acids,
neuropeptides. Action of neurotransmitter depends on type of receptors in a
specific synapse. Some neurons produce one type of neurotransmitter, while others
produce two or three.