Flight or flee artifact
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Transcript of Flight or flee artifact
You don't have to flee any longer
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Body’s Digest
The cerebral cortex is a thin layer of
gray matter made up of neuron dendrites
and cell bodies that compose the surface
of the cerebrum. Consists of 2 halves a
right and left half. It controls sensory,
motor, consciousness, language, emotions
and memory. (1) (393)
STRUCTUREANDFUNCTION
Somatic Sensory pathways in the CNS:
For the cerebral cortex to perform its
sensory functions, impulses must first
be conducted to the sensory pathways.
Sensory paths to the cerebral cortex
are crossed. There are three main pools
of sensory neurons there are primary,
secondary, tertiary. (1) (399)
Somatic motor pathways in the
CNS: For the cerebral cortex to per-
form its motor functions, impulses
are conducted from its motor areas
to skeletal muscles by somatic mo-
tor pathways. Consists of motor neu-
rons that conduct impulses from the
CNS to skeletal muscles.(1) (400)
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Make it work sista and fight!
With the Sensory and motor pathways you are now fully aware of your
brains messaging throughout nerve impulses and the power with in your-
self. You’re practically a superhero!
PeripheralNervousSys.
There are thirty-one pairs of spinal
nerves that are connected to the spi-
nal cord, although they don’t have
special names they are numbered ac-
cording to the level of the vertebral
column at which they emerge from
the spinal cavity. (1)
Structure of the Spinal Nerves:
The structure of the spinal nerves
is separated into two sections, which
are attached to the spinal cord in
terms of roots. These roots are the
ventral and dorsal. The dorsal root
of each spinal nerve is easily recog-
nized by a swelling called the dorsal
root ganglion, or spinal ganglion.
(1)
Plexuses:
The ventral rami of most spinal
nerves subdivide to form complex
networks called plexuses. There
are four major types of plexuses,
and they are the cervical plexus,
the brachial plexus, the lumbar
plexus and the sacral plexus. (1)
Cervical Plexus is found deep with-
in the neck, the parts supplied
with this are the sensory to the
back of the head, front of the neck,
and upper part of the shoulder; mo
PeripheralNervousSys.
tor to numerous neck muscles. (1)
Brachial Plexus is found deep
within the shoulder. Lumbar Plex-
us, which is formed by the inter-
mingling of fibers from first four
lumbar nerves. This network of
nerves is located in the lumbar
region of the back near the soas
muscle. Sacral Plexus are the fi-
bers from the fourth and fifth
lumbar nerves and the first four
sacral nerves. It lies in the pelvic
cavity on the anterior surface of
the piriformis muscle.
Dermatomes & Myotomes:
Dermatomes- regions of skin surface ar-
ea supplied by afferent (sensory) fibers of
a given spinal nerve. (1)
Myotomes- skeletal muscles supplied by
efferent (motor) fibers of a given spinal
nerve. (1)
Cranial Nerves:
There are twelve pairs of cranial nerves
that connect to the brain, mostly to the
brainstem. They are also made up of
bundles of axons, which are the mixed
cranial nerve where axons of sensory and
PeripheralNervousSys.
motor neurons. Sensory cranial
nerve- axons of sensory neu-
rons only. Motor cranial nerve-
mainly axons of motor neurons
and a small number of sensory
fibers (proprioceptors).
1) Olfactory Nerve
2) Optic Nerve
3) Oculomotor Nerve
4) Trochlear Nerve
5) Trigeminal Nerve
6) Abducens Nerve
7) Facial Nerve
8) Vestibulocochlear Nerve
9) Glossopharyngeal Nerve
10) Vagus Nerve
11) Accessory Nerve
12) Hypoglossal Nerve
Afferent & Efferent Nerves:
There are two functional divi-
sions of the peripheral nervous
system which are the afferent
(sensory) division and the effer-
ent (motor) division. The effer-
ent division is divided further
into the somatic motor nervous
system and the efferent portions
of the autonomic nervous sys-
tem. (1)
PeripheralNervousSys.
Autonomic Nervous System:
Structure: : : : each pathway is up
of autonomic nerves, ganglia,
and plexuses, which are made of
efferent autonomic neurons. All
autonomic neurons function in
the reflex arcs. Efferent auto-
nomic regulation ultimately de-
pends on the feedback from sen-
sory receptors. Relay of two ef-
ferent autonomic neurons con-
ducts information from central
nervous system to autonomic ef-
fectors:
1) Preganglionic neuron- conducts
impulses from the central nervous
system to an autonomic ganglion.
2) Postganglionic neuron- efferent
neuron with which a preganglion-
ic neuron synapses with autonom-
ic ganglion
Function: : : : the autonomic nervous sys-
tem functions to regulate visceral
effectors in ways that tend to main-
tain or quickly restore homeostasis.
Sympathetic and Parasympathetic
divisions are tonically active, often
exerting antagonistic influences on
visceral effectors.
PeripheralNervousSys.
Doubly innervated effectors con-
tinually receive both sympathet-
ic and parasympathetic impuls-
es, and the summation of the
two determine the controlling
effect.
Sympathetic Nervous System:
The purpose of the sympathetic
nervous system is that under
resting conditions, the sympa-
thetic division can act to main-
tain the normal functioning of
doubly innervated autonomic ef-
fectors. As a result the sympa-
thetic impulses function to
maintain normal tone of the smooth
muscle in blood vessel walls. The ma-
jor function of this system is that it
serves as an “emergency” system-
the “fight-or-flight” reaction. (1)
Parasympathetic Nervous System:
The purpose of the parasympathetic
nervous system is the dominant con-
troller of most autonomic effectors
most of the time. This includes Ace-
tylcholine which slows the heartbeat
and acts to promote digestion and
elimination. (1)
TheBrainstem
Three divisions of the brain
make up the brainstem, the me-
dulla oblongata, the pons, and
the midbrain. (1)
The medulla oblongata is the
part of the brain that attaches
to the spinal cord, it is about an
inch in length and is separated
from the pons above by a hori-
zontal groove. It is composed of
white matter (projection tracts)
and a network called the reticu-
lar formation. In this reticular
formation there are various nu-
clei, or clusters of neuron cell
bodies. (1)
The pons, like the medulla, is also
composed of white matter and retic-
ular formation. Fibers that run
transversely across the pons and
through the middle cerebellar pe-
duncles into the cerebellum make up
the external white matter of the
pons and give it its arching appear-
ance. (1)
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TheCerebellum
The midbrain lies below the
pons and above the cerebrum.
Both white matter and reticular
formation compose the mid-
brain. Extending divergently
through it are two ropelike
masses of white matter named
cerebral peduncles. Tracts in
the peduncles conduct impulses
between the midbrain and cere-
brum. (1)
The function of the brainstem
is similar to the spinal cord. It
performs sensory, motor and re-
flex functions
The cerebellum is the second larg-
est part of the brain. A transverse
fissure separates the cerebrum from
the cerebellum. The cerebellum is
full of white matter much like the
cerebrum, it also has sulci and gyri
along its surface. The cerebellum is
composed of two larger lateral
masses the cerebral hemisphere and
the Vermis. (1)
The internal white matter of the
cerebellum is composed of some
short and some long tracts. The
shorter tracts conduct impulses
from neuron cell bodies located in
TheCerebellum
the cerebellar cortex to neurons
whose dendrites and cell bodies
compose nuclei located in the
interior of the cerebellum. The
longer tracts conduct impulses
to and from the cerebellum. fi-
bers of the longer tracts con-
duct impulses to and from the
cerebellum. Fibers of the longer
tracts enter or leave the cere-
bellum by way of its three pairs
of peduncles, inferior cerebellar
peduncles, middle cerebellar pe-
duncles, and superior cerebellar
peduncles. An important pair of
cerebellar nuclei are the den-
-tate nuclei, one of which lies in each
hemisphere. Tracts connect these
nuclei with the thalamus and with
motor areas of cerebral cortex. By
means of these tracts cerebellar im-
pulses are able to influence the mo-
tor cortex and vice versa. (1)
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TheDiencephalon
The functions of the cerebel-
lum all have to do with the con-
trol of skeletal muscles. The
cerebellum acts with the cere-
bral cortex to produce skilled
movements by coordinating the
activities of groups of muscles.
The cerebellum also helps to
control posture and maintain
balance. (1)
The Diencephalon is made up of
several structures. The two
main structures are the thala-
mus and hypothalamus. (1)
The thalamus is a mass of gray
matter made up of many nuclei.;two
in which are the geniculate bodies,
located in the posterior region of
each lateral mass. The geniculate
bodies play a role in processing audi-
tory and visual input. Large numbers
of axons conduct impulses into the
thalamus from all parts of the brain.
These axons terminate the thalamic
nuclei, where they synapse with neu-
rons whose axons conduct impulses
out of the thalamus to all areas of
the cerebral cortex. Thus the thala-
mus is a relay station for sensory im-
pulses on their way to the cerebral
cortex. (1)
TheDiencephalon
The thalamus’ functions are
taking impulses from appropri-
ate receptors and produce a
conscious recognition of less
critical sensations of pain like
temperature and touch. Plays
part in emotions/ association,
the thalamus also plays a part
in arousal and producing com-
plex reflex movements. (1)
The hypothalamus consists of
several structures that are un-
der the thalamus. It is small
but extremely important., be-
cause it contributes to both sur-
vival and the enjoyment of life. It
functions as a link between the mind
and the body. And also links to the
nervous and endocrine system. The
hypothalamus serves as a regulator
and coordinator of autonomic activi-
ties and provides a crucial role in the
route by which emotions can express
themselves in changed bodily func-
tions. It also plays a vital role in wa-
ter balance, waking state, appetite,
and body temp. (1)
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TheMeninges
Three meninges: dura mater,
arachnoid membrane, pia mater (2)
Inflammation of meninges:
meningitis (2)
Dura mater: made of strong
white fibrous material, outside of brain (2)
Arachnoid membrane: delicate,
cob like membrane, lies between dura and pia mater(2)
Pia mater: transparent matter that adheres to the outer sur-face if the brain and spinal cord, contains blood vessels (2)
Function of CSF (cerebrospinal flu-
id)
• Provides supportive, protective cushion (2)
• Reservoir of circulating fluid, which is monitored by the brain to detect changes in internal environ-ment (2)
Found within subarachnoid space
around the brain, spinal cord & sur-
rounding cavities, and canals of the
brain and spine. (2)
Spinal cord
• Within spinal cavity and extends from the foramen magnum to the lower border of the first lumbar ver-
TheMeninges
-tebrae (2)
• Oval shaped cylinder that ta-pers slightly from above down-ward with bulges in cervical re-gion & lumbar region (2)
Nerve Roots
• Carry sensory and motor info into spinal canal (fibers of dor-sal nerve root and central nerve root) (2)