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THE NERVOUS SYSTEM
ORGANS & DIVISIONS OF THE NERVOUS SYSTEM
1. ________________ (CNS) - brain & spinal cord
2. ________________ (PNS) - all nerves
3. ________________
FUNCTIONS:
________________: gather information
________________: movement
________________: creative, memory, perception, thought
CELLS OF NERVOUS SYSTEM:
1. NEURONS - consist of:
________________ - conduct impulses to cell body
________________- conducts impulse away from body
________________ - main portion of cell
________________ - a white fatty substance around the neurons (outside the CNS)
________________ - found around axons; produces myelin
________________- membrane of Schwann cell
________________ - nerve tissue containing myelin
________________ - nerve tissue without myelin
________________ - indentations between Schwann cells
________________ - gap between neurons
2. Sensory neurons conduct impulses to ________________
3. ________________ neurons conduct impulses away from CNS
4. ________________ connect the sensory & motor neurons
5. ________________ (connective tissue):
________________ - star-shaped cells that anchor small blood vessels to neurons
________________ - small cells that destroy microorganisms and harmful particles
________________ - produce the myelin in the CNS
________________ - a common type of brain tumor in this tissue.
________________ - consist of bundles of axons
NERVE IMPULSE: a ________________ wave of electrical negativity traveling along the membrane surface.
________________ potential - a nerve cell at rest has a more positive charge outside the membrane (due to Na+) and a negative charge inside the membrane. This creates positive and negative poles like a battery.
1. Stimulus increases ________________ of membrane to sodium
2. Sodium ions rush in and create a positive charge inside and negative outside (________________)
3. Depolarization in one part of the membrane ________________ the membrane next to it so that a negative wave travels along membrane.
4. Immediately after depolarization (one-thousandth of a second) active transport pumps Na+ back out of the cell and re-establishes the positive charge outside (________________)
________________ - allows impulses to jump from one node to the next.
Impulses in ________________ fibers may travel at 120 m/sec.
Impulses in ________________ fibers may travel 0.5 m/sec.
________________: chemical compounds released from the synaptic knobs of axon terminals into synaptic cleft
Neurotransmitters bind to ________________ sites on post-synaptic neuron which changes its ________________ and starts a new impulse
Examples of neurotransmitters:
________________, Norepinephrine (noradrenalin), ________________, ________________, ________________ (adrenalin), ________________
Catecholamines - a group of compounds that is involved in sleep, motor function, mood, and pleasure recognition
________________ and Enkephalins inhibit pain.
Neurotransmitters are decomposed by ________________ after their release or moved back into the synaptic knobs to prevent continuous stimulation.
REFLEX ARCS (________________ responses)
1. Nerve impulses are conducted from receptors to effectors stimulating a muscle or ________________ to react. (reflexes)
2. Two-neuron Arcs: sensory to motor neurons
3. Three-neuron Arcs: sensory to interneuron to ________________ neurons
SPINAL CORD
Outer, white matter made of ________________
Inner, gray matter made of ________________
Functions as center for spinal cord reflexes
Functions as sensory tract for carrying impulses to and from brain.
Spinal cord ends at the 4th lumbar vertebra.
Loss of sensation = ________________
Loss of movement = ________________
SPINAL NERVES (________________ pairs)
8 cervical nerves; 12 thoracic nerves; 5 lumbar nerves; 5 sacrospinal nerves; 1 coccygeal nerve
________________ - surface area of skin supplied by a single spinal nerve
Structure: contain dendrites of sensory neurons and axons of motor neurons
Function: conduct impulses necessary for sensations and movement through ascending tracts and descending tracts
AUTONOMIC NERVOUS SYSTEM
Autonomic Nervous System - consists of ________________ neurons that conduct impulses from the central nervous system to ________________, ________________, and ________________ epithelial tissue; or: Nervous system structures that regulate the body's involuntary functions
Autonomic neurons - motor neurons that conduct ___________ the central nervous system _________ the cardiac muscle, smooth muscle, and glandular epithelial tissue; including ________________ autonomic neurons that conduct from spinal cord or brain stem to an autonomic ganglion; and ________________ neurons that conduct from autonomic ganglia to cardiac muscle, smooth muscle, or glandular epithelial tissue
Autonomic or ________________ effectors - tissues to which autonomic neurons conduct impulses, cardiac muscle, smooth muscle, and glandular epithelial tissue.
TWO DIVISIONS:
1. ________________ (or thoracolumbar system)
2. ________________ (or craniosacral system)
SYMPATHETIC NERVOUS SYSTEM
Structure:
1. Dendrites and cell bodies of sympathetic preganglionic neurons are located in gray matter of ________________ and upper ________________ segments of spinal cord.
2. Axons leave cord in anterior roots of spinal nerves, extend to sympathetic or colateral ________________, and synapse with several ________________ neurons whose axons extend out in spinal nerves or autonomic nerves to terminate in visceral effectors
3. The sympathetic ganglia form a ________________ in front of and at each side of spinal column
Functions:
1. Serves as the ________________or stress system, controlling visceral effectors during strenuous exercise and strong emotions
2. Group of changes induced by sympathetic control is called the ________________ syndrome
3. Functions include: ________________, constricts most blood vessels but dilates blood vessels to ________________, decreases peristalsis of digestive tract, inhibits defecation and urination, dilates pupils, stimulates goose pimples, increases ________________, decreases digestive juices
PARASYMPATHETIC NERVOUS SYSTEM
Structure:
1. Parasympathetic preganglionic neurons have their ________________ and cell bodies in gray matter of the ________________ stem and of the ________________ segments of cord
2. Their axons leave brain stem by way of cranial nerves III, VII, IX, X, and XI and leave the cord by some pelvic nerves
3. They terminate in parasympathetic ________________ located in head and thoracic and abdominal cavities ________________ visceral effectors
4. Each parasympathetic preganglionic neuron synapses with postganglionic neurons to ________________ effector
Function: Dominates control of many visceral effectors under ________________ conditions
Balances the effects of the sympathetic nervous system. Produces the ________________ stimulus after a scare or anger.
AUTONOMIC CONDUCTION PATHS
Consist of two-neuron relays, a preganglionic neuron from the CNS to the autonomic ganglia, then a ________________ neuron to the visceral effector
________________ neurons (non-autonomic neurons) reach directly from CNS to visceral effector.
AUTONOMIC NEUROTRANSMITTERS
1. ________________ fibers - preganglionic axons of both sympathetic and parasympathetic, and the postganglionic axons of the parasympathetic system release acetylcholine
2. ________________ fibers - postganglionic neurons of the sympathetic system release norepinephrine (noradrenaline)
3. ________________ and ________________ are also released by somatic motor neurons and CNS neurons
AUTONOMIC NERVOUS SYSTEM AS A WHOLE
1. Regulates the body's automatic functions in ways that tend to maintain or quickly restore homeostasis
2. Many visceral effectors are doubly innvervated, and receive fibers from both sympathetic and parasympathetic systems
3. Autonomic nervous system is not autonomous or independent from other parts of the nervous system; the hypothalamus and other parts of the brain influence both
COVERINGS AND FLUID SPACES OF THE CNS
Coverings:
1. Cranial Bones and vertebrae
2. Cerebral & spinal meninges : ________________, ________________ , ________________
Fluid Spaces:
1. ________________
2. ________________
3. ________________
________________ - a network of capillaries where fluid filters from the blood into the ventricles.
________________ - a duct which allows the cerebrospinal fluid to flow from the ventricles to the spinal cord.
________________ - an enlarged head caused by accumulation of fluid around the brain, due to blocked ducts.
DIVISIONS OF THE BRAIN
A. Brain Stem: Consists of white matter with bits of gray
1. ________________
2. ________________
3. ________________
Reflex centers for _________, ________________, blood vessel dilation.
Sensory tracts in brain stem to conduct impulses to higher parts of brain.
Motor tracts transmit impulses from higher parts of brain to cord.
4. ________________: Consists of hypothalamus and thalamus
________________ - consists of posterior pituitary gland, pituitary stalk, and paraventricular and supraoptic nuclei.
a. Acts as major center for controlling __________ __________ ___________ (controls internal organs).
b. Controls hormone secretion by both anterior and posterior ____________glands; therefore regulating most other endocrine glands.
c. Acts as a center for controlling ____________.
d. Maintains ___________ state.
e. Contains reward and punishment centers.
________________ structure and function
a. Rounded mass of gray matter in each cerebral hemisphere
b. Relays sensory impulses to cerebral cortex sensory areas
c. Involved in pleasure/displeasure sensations
C. ________________
1. Largest part of human brain
2. ________________ (outer layer) divided into lobes and hemispheres; highly convoluted.
3. Cerebral gray matter (interior) made of axons.
4. Functions include ________________, ________________, ________________, ________________
5. ________________ = ridges or convolutions
6. ________________ = grooves
7. ________________ - connects the hemispheres
8. ________________ hemisphere - logical, right hand control, language, math skills, reasoning
9. ________________ - left hand control, musical, artistic, space perception, insight, imagination
D. ________________
1. Second largest part of brain
2. Controls ________________
E. Cranial Nerves - ________________ pairs
1. ________________ - smell
2. ________________ - vision
3. ________________ - eye movements
4. ________________ - eye movements
5. ________________ - chewing, facial senses
6. ________________ - turn eyes outward
7. ________________ - facial muscles
8. ________________ - hearing, balance
9. ________________ - swallowing, taste
10. ________________ - throat, heart regulation
11. ________________ - shoulder, turn head
12. ________________ - tongue
SENSE ORGANS
A. All receptors are sense organs
B. Five types of sensory receptors
________________
________________
________________
________________
________________
Sensations are feelings that occur when sensory impluses are interpreted by the brain.
C. Special sense organs include the eye, ear, nose, and tongue
D. Somatic Senses:
Touch and pressure
Sensory nerve fibers (free ends)
________________ corpuscles (light touch)
________________ (deep pressure)
Temperature sensors:
Heat receptors & Cold receptors
Pain receptors:
________________ pain fibers - fast acting; sharp pain
________________ pain fibers - slow acting; dull aches
Referred pain - pain from visceral organs may seem as if coming from another part of the body.
E. Special Senses
________________ sense organs
1. Receptors for fibers of olfactory nerve lie in the olfctory ________________
2. Olfactory receptors extremely sensitive but easily ________________
3. Odor-causing chemicals stimulate action potentials that are interpreted as specific odors by the brain.
Gustatory organs
1. Receptors are called taste buds (found on the ________________ of the tongue)
2. Cranial nerves seven and nine carry gustation impulses
3. Taste buds are ________________
4. Four tastes: ________________, ________________, ________________, ________________
5. Gustatory and olfactory senses work together
Ear
1. External ear = ________________ (auricle) and auditory canal
2. Middle ear includes ________________, ________________, ________________, mucous membranes, eustachian tube openings and mastoid sinus openings
3. Internal Ear consists of a bony labyrinth surrounding a membranous labyrinth divided into ________________ canals, ________________, and vestibule.
The cochlea contains a basilar membrane that extends all the way to the apex or end of the cochlear duct.
Organ of ________________ - hearing receptors located on the basilar membrane (made of receptor hairs that respond to different frequencies).
Steps in hearing:
Sound waves enter outer ear
Sound waves produce vibrations in the tympanic membrane.
Vibrations transfer from tympanic membrane to malleus, incus, and stapes.
Vibrations pass through the oval window to fluid in the cochlea.
Different frequencies of vibrations in the fluid stimulate different receptor hairs in the membrane.
Receptor cells act like neurons, depolarizing and sending an impulse to the nearby neurons.
Neurons carry impulse to the temporal lobe of the brain by way of the vestibulocochlear nerve (cranial nerve #8).
Balance (Equilibrium):
________________ equilibrium (sense position of head)
________________ (sense motion)
The organs of static equilibrium are located inside the vestibule. The utricle and saccule are chambers within the vestibule. The ________________ (a set of hair receptors inside the utricle) senses the pull of gravity on a gelatinous material that fills the space.
The organs of dynamic equilibrium are the ________________, at the base of which is a swelling called the ampulla. Inside the ampulla are the ________________ which also contain sensory hairs that respond to movement of the fluid in the semicircular canals.
D. Eye
3 distinct layers:
Outer (________________) Tunic
________________- tough outer coat of eyeball
________________ - transparent part of sclera over eyeball
________________ - mucous membrane that covers the front surface of eyeball lining and lines lid
Middle (________________) Tunic:
________________- middle layer of eyeball; Contains ciliary muscle and iris
________________ - changes shape of lens (focuses vision)
________________ - colored part of eye; dilates or constricts pupil
________________ - hole in center of iris
________________ - transparent body behind pupil that focuses light on retina
________________ - fluid in cavity in front of lens
________________ - fluid in cavity behind lens
Inner (________________) tunic:
________________ - innermost coat of eye; contains rods and cones
________________ - receptors for dim light
________________ - receptors for bright light and colored light. There are three basic types: red, green, & blue
________________ - a yellowish spot on central region of the retina.
________________ - the depressed center of the macula lutea; this is where vision is the sharpest.
________________ - an area in the retina where no rods and cones exist. The optic nerve attaches here.
Common Eye problems:
________________ - nearsightedness; eyeball shape too short
________________ - farsightedness; eyeball shape too long
________________ - lens loses flexibility; need bifocals
________________ - a flaw or blur in the lens
________________ - caused by too much pressure in the eyeball
________________ - clouded lens
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