nervous system Flashcards
where do sensory nerves carry information?
to the central nervous system
where do motor nerves carry information?
away from the central nervous system
neurons
individual nerve cells that conduct electrical impulses in response to stimulus
what two basic types of cells makes up nervous tissue?
neurons and neuroglial cells
what are the 3 parts of a neuron?
dendrites - highly branched projections that recieve impulse
nerve cell body - contains the nucleus and many other organelles
axon - a projection from the nerve cell body that conducts the electrical impulse toward its destination.
neuroglial cells
cells that support and protect the nervous system
- schwan cell in the (PNS)
what do some neuroglial cells produce?
myelin - a fatty substance that acts as insulation for many axons so that they can conduct electrical impulses faster.
they do not conduct electrical impulses
synapse
the point at which the axon of one neuron meets the dendrite of the next neuron
synaptic cleft
a gap between two neurons that electrical impulses cannot pass directly across
neurotransmitter
helps electrical impulses pass through the synaptic cleft
what makes up the central nervous system?
brain and spinal cord
gray matter
composed of unsheathed or uncovered cell bodes and dendrites
- located on outside of brain
white matter
myelinated nerve fibers
- the myelin sheath makes the nervous tissue appear white
- located on inside of brain
tracts
bundles on nerve fibers interconnecting different parts of the central nervous system.
what are the 4 sections of the brain?
- cerebrum
- cerebellum
- diencephalon
- brain stem
cerebrum
located in the upper portion, and it’s the area that process thoughts, judgement, memory, problem solving, and language
what is the outer layer of the cerebrum called?
cerebral cortex - composed of folds of gray matter
gyri and sulci
gyri - elevated portions of the cerebrum, or convulsions
sulci - what gyri are separated by, fissues, or valleys.
what are the 4 lobes of each hemisphere?
- frontal lobe - personality, motor function, speech
- temporal lobe - hearing and smell
- parietal lobe - language and interpretation
- occipital lobe - vision
cerebellum
- the second largest portion of the brain, located beneath the posterior part of the cerebrum.
- this part of the brain aids in coordinating volutary body movements and maintaing balance and equilibrium.
- it also redifines the muscular movement that is initiated in the cerebrum
diencephalon; contains which two most critical areas of the brain?
thalamus - composed of gray matter and act as a center for relaying impulses from the eyes, ears, and skin to the cerebrum.
- our pain perception is controlled by the thalamus
hypothalamus - controls body temperature, appetite, sleep, sexual desire, and emotions.
- it it responsible for controlling the (ANS), cardiovascular system, digestive system, and the release of hormons from the pituitary gland.
brain stem; what are the three components this area contains?
midbrain - acts as a pathway for impulses to be conducted between the brain and the spinal cord
pons - a term meaning “bridge”, connects the cerebellum to the rest of the brain.
medulla oblongata - connects the brain to the spinal cord.
- contains the centers that control respiration, heart rate, temperature, and blood pressure.
- this is also the site where nerve tracts cross from one side of the brain to control functions and movement on the other side of the body.
what are ventricles and cerebrospinal fluid?
found in each cerebral hemisphere, thalamus, and cerebellum, these contain cerebrospinal fluid (CSF), which is water and clear fluid that provide protection from shock or sudden motion to the brain and spinal cord.
what is the function of the spinal cord?
to provide a pathway for impulses traveling to and from the brain
what forms the spinal cavity or vertebral canal?
- the 33 vertebrae of the backbone line up to form a continuous canal
what is the spinal cord protected by and where does it flow?
cerebrospinal fluid, it flows down the center of the spinal cord within the central canal.
what is the inner core of the spinal cord classified as?
gray matter
what is the white matter of the spinal cord?
ascending tracts - carry sensory information to the brain.
descending tacts - carry motor commands down from the brain to a peripheral nerve.
meninges
three layers of connective tissue membrane surrounding the brain and spinal cord
also known as blood brain barrier
dura mater
outer layer very tough and is located below the skull
sub-dural space
actual space between the dura mater and arachnoid layer
arachnoid layer
looks like a spider web. thin, delicate layer attached to the pia mater by weblike filaments.
subarachnoid space
the cerebral spinal fluid is located here
pia mater
innermost membrane layer and is applied directly to the surface of the brian and spinal cord.
what does the PNS include?
12 pairs of cranial nerves and 31 pairs of spnial nerves
nerve
a group or bundle of axon fibers located outside the CNS that carries messages between the central nervous system and various parts of the body.
where do cranial nerves come from?
the brain, mainly at the medulla oblogata
where do spinal nerves come from?
split off from the spinal cord, and one pair (a left and a right) exits between each pair of vertebrae.
nerve root
the point where each type of nerve is attached to the CNS
- although most nerves carry information to and from the central nervous system, individual neurons carry information in only one direction.
what are the 5 main sections of the vertebral column
- cervical
- thoracic
- lumbar
- sacrum
- coccyx or coccyxgeal
afferent neurons
also known as sensory neurons, carry sensory information from a sensory receptor to the central nervous system.
efferent neurons
also known as motor neurons, carry activity instructions from the central nervous system to muscles or glands in the body.
ganglion
a knot-like mass where the nerve cell bodies of the neurons forming the nerve are grouped together.
ANS (autonomic nervous system)
involved with the control of involuntary or unconscious bodily function
- It may increase or decrease the activity of the smooth muscle found in viscera and blood vessels, cardiac muscle, and gland.
Olfactory (sensory)
transports impulse for sense of smell
Optic (sensory)
Carries impulses for sense of sight
Oculomotor (motor)
Motor impulses for eye muscle movement and the pupil of the eye.
Trochlear (motor)
Controls superior oblique muscle of eye on each side
Trigeminal (mixed)
Carries sensory facial impulses and control muscles for chewing; branches into eyes, forehead, upper and lower jaw.
Abducens (motor)
Controls an eyeball muscle to turn eye to side
Facial (mixed)
Control facial muscles for expression, salvation, and taste on two-thirds of tongue (anterior)
Vestibulocochlear (mixed)
also called auditory nerve
Responsible for impulses of equilibrium and hearing
Vagus (motor)
Supplies most organs in abdominal and thoracic cavities.
Accessory (motor)
Controls the neck and shoulder muscles
Hypoglossal (motor)
Controls tongue muscles.
what are the two brances of the ANS?
sympathetic and parasympathetic branch
sympathetic branch
the sympathetic nerves control the “ fight-or-flight” reaction during times of stress and crisis.
- these nerves increase heart rate, dilate airways, increase blood pressure, inhibit digestion, and stimulate the production of adrenaline during a crisis.
parasympathetic branch
the parasympathetic nerves serve as a counterbalance for the sympathetic nerves, the “rest-and-digest” reaction.
- therefore, they cause heart rate to slow down, lower blood pressure, and stimulate digestion.
somatic nerves
serve as the skin and skeletal muscles, and are mainly involved with the conscious and voluntary activities of the body.
- the large variety of sensory receptors found in the dermis layer of the skin use somatic nerves to send their information, such as touch, temperature, pressure, and pain, to the brain.
- these are also the nerves that carry motor commands to skeletal muscles.
when the electrical transmission reaches the synapse, what does it convert to?
chemical transmission