Nervous System Flashcards
Structural division of the nervous system
CNS (brain and spinal chord) and PNS (everything else)
Functional division of nervous system
Somatic nervous system and autonomic nervous system
Two types of cells in nervous tissue
Neurons (nerve cells) neuroglia cells (glial cells for support)
Neurons are specialized for
rapid communication
A neuron is composed of a ___ with processes called ____ and an ____ that carry impulses.
cell body, dendrites, axon
Myelin
sheath around axons that increases impulse transmission. Lipid
Two types of neurons
Multipolar motor neurons and pseudo unipolar sensory neurons
Multipolar neurons
two or more dendrites and. single axon that can have more than one collateral branch **MOST COMMON IN CNS AND PNS
Pseudounipolar sensory neurons
short and apparently single process extending from the cell body The common process then separates
all the motor neurons that control skeletal muscle and those comprising the ANS are ___ neurons
multipolar
The common process of pseudounipolar sensory neurons separates into
a peripheral process (from receptors on organs to the cell body) and a central process (continues from the cell body to the CNS).
Where are the cell bodies of pseudonipolar neurons located? What are they part of?
outside the CNS in sensory ganglia. Part of the PNS
Where and how to neurons communicate
at the synapse by the release of NT which can either excite of inhibit another neuron
Neuroglia
five times more abundant than neurons. non-excitable cells, that help with supporting, insulating and nourishing the neurons
In the CNS, neuroglia include
oligodendrogia, astocytes, ependymal cells, microglia
Neuroglia cells in the PNS include
satellite cells (posterior root), and Schwann Cells (autonomic ganglia)
CNS
brain and spinal cord, its function is to integrate and coordinate signals both incoming and outgoing and then carry out higher functions.
Nucleus
collection of nerve bodies in the CNS
tract
bundle of nerve fibers or axons
grey matter
where nerve cell bodies are
white matter
interconnecting fiber tract systems
Grey matter appearance
looks like an H producing horns (L and R anterior (ventral) and posterior (dorsal) horns)
What protects the CNS
the meninges and the CSF
The meninges
the Pia mater (thin innermost layer), [CSF GOES HERE] arachnoid mater and the dura mater (thick outermost layer)
Dura mater in the brain vs the spinal cord
in the brain, the dura mater touches the skull or the brain case. In the spinal cord, the dura mater does not touch bone, it is separated by the epidural space.
PNS
nerves connect the CNS to peripheral structures. Its role is to carry impulse to and from the CNS
Nerve fiber
nerve fiber, neurolemma (cell membranes of Schwann cells that surround the axon) and endoneurual connective tissue
Nerolemma
cell membranes of the Schwann cells that immediately surround the axon
Neurolemma can take two forms
- myelinated nerve fiber has Schwann cells specific to an individual axon, set in a series of enwrapping cells to form myelin
- unmyelinated: multiple axons are separately embedded in the cytoplasm of the cellThese Schwann cells o not produce myelin
Components of a nerve
- a bundle of nerve fibers outside of the CNS
- the CT that surround and bind the the nerve fibers together
- Blood vessels that nourish the nerve fibers
Nerve fiber connective tissue coverings
- Endoneurium: delicate innermost layer
- Perineurium: dense layer of CT that encloses a fascicle of nerve fibers. Provides protection
- Epineurium: thick layer that encompasses a group of fascicles. Fatty tissue, blood vessels and lymph
Ganglion
a collection of nerve cell bodies outside of the CNS
Afferent (sensory) fiber
Carries impulses from sensory organs like the eyes and receptors to the CNS
Efferent (motor) fibers
Carry impulses from the CNS to the effector organs
Cranial nerves
ext cranial cavity through foramina. ID’d by either their descriptive name of a roman numeral
How many pairs of cranial nerves arise from the brain, and how many arise from the spinal cord
11 pairs from the brain, and one from the superior part of the spinal cord
Spinal (segmental) nerves
exit the vertebral column through intervertebral foramina. they arise in pairs from specific segments of the spinal cord
How many pairs of spinal nerves are there? and how are they identified
By letter and number, like C6 and there are 31 pairs
Spinal nerves arise from ____ and converge to two nerve roots; ______ and _______
rootlets, and they converge into anterior (ventral) roots and posterior (dorsal) roots
Anterior (ventral) nerve root
motor (efferent) fiber passing from the nerve cell bodies in the anterior horn to the effector organs.
Posterior (dorsal) root
sensory (afferent) goes into the posterior root spinal cord grey matter
the posterior and anterior root unite where? and what do they form? which splits into what?
they unite right proximal to the intervertebral foramen, and they form a spinal nerve, which branches into two rami, (ramus).
the posterior and anterior rami cary both…?
sensory and motor fibers
Somite period
when segments are more. pronounced during embryonic development. tissues that will be muscle or bone will cause a biscuit like protrusion (somites) from the fetal spinal column
Medial sides of the somites are…
sclerotomes
Ventrally migrating sclerotomes surround the ____ and are the beginning of the
notochord, of the bodies of vertebrate
dorsal migrating sclerotomes surround the _____ and become the …
neural tube, and the beginning the neural arch of the vertebrate
Lateral aspects of the somites are called…
dermatomyotomes
cells of dermatomyotomes that migrate posteriorly give rise to…
intrinsic or epaxial (deep) muscles of the backend overlying dermis
cells of the dermetomyotomes that migrate anteriorly give rise to…
the hypaxial muscles of the anterolateral trunk and limbs of the dermis
Dermatome
the unilateral area of skin supplied by a single spinal nerve
Myotome
the unilateral muscle that is supplied by a single nerve
as spinal nerves emerge form the intervertebral foramina, they are divided into two rami known as
posterior (primary) rami and the anterior (primary) rami
Posterior rami
supply nerve fibers to the synovial joints, the deep (epaxial) muscles of the back and the overlying skin
Anterior rami
supply nerve fibers to the skin and hypaxial muscles of the anterior and lateral regioins of the trunk as well as the upper and lower limbs
when anterior rami merge they form
somatic nerve plexus’
how do cranial nerves differ from dermatomes
there is little overlap when it comes to what part of the skin is affected by what cranial nerve. With dermatomes, there can be a number of nerves affecting the area based on plexus’ whereas with the face it is pretty clear with the cranial nerves what is causing what
Types of somatic fibers
general sensory fibers and somatic motor fibers
General sensory fibers
send sensations from the body to the CNS. Can be extroceptive like touch pain, temp or can be PROPRIOCEPTIVE SENSATIONS like from muscles tendons or joints (like position of these structures) LIMBS IN SPACE
Somatic motor fibers
transmit signals to the skeletal (VOLUNTARY) muscles
types of visceral fibers
visceral sensory fibersand visceral motor fibers
visceral sensory fibers
transmit pain or visceral reflex sensations (like BP) to the CNS from the organs and the blood
Visceral motor fiber
send impulses to smooth (involuntary) muscles and glands.
Two variations of visceral motor fibers, and their roles
presynaptic and postsynaptic, work together to get impulses from CNS to smooth muscles or glands.
General sensory and visceral sensory fibers are ____ neurons, with cell bodies located ____ of the CNS in _______.
pseudo unipolar neurons, outside, in spinal or cranial sensory ganglia
Motor fibers are axons of ____ neurons
multipolar
The cell bodies of somatic motor and presynaptic visceral motor neurons are found in the ___
grey matter of the spinal cord
Cell bodies of the postsynaptic motor neurons are located ___ the CNS in _____.
Outside the CNS in autonomic ganglia
Special sensory fibers
can be used to describe the 5 senses.
Somatic motor system
provides sensory and motor innervation to all parts of the body, except the viscera in the cavities, smooth muscle and glands. ONLY SKELETAL MUSCLE
Somatic motor system innverates ___ muscles that cause a stimulating ___ and _____ movement.
skeletal muscles, voluntary and reflexive (muscles contracting like after touching a hot iron
Autonomic nervous system
(visceral nervous system or visceral motor system)
smooth muscle, glands, heart. INVOLUNTARY
Efferent nerve fibers of the ANS are divided into two parts…
parasympathetic and sympathetic
Conducting impulses from the CNS to the effector organ involves what kind of neurons?
two multipolar neurons, the presynaptic (preganglionic) neuron and the postsynaptic (postganglionic)
cell bodies of the presynaptic neurons are in the ____ of the CNS, and only synapses with the cell bodies of ____
grey matter, postsynaptic neurons
postsynaptic neurons are located ____ the CNS in _____. Its fibers terminate on the _____
outside the CNS, in autonomic ganglia, effector organ
the anatomical distinction between the sympathetic and parasympathetic divisions of the ANS are based on
- location of the presynaptic cell bodies
2. which nerves connect the presynaptic fibers from the CNS
somatic nervous system provides what, to where?
parts of the CNS and PNS that provide sensory and motor innervation to the whole body (except the viscera, muscles and glands
Autonomic nervous system (AKA) have what kinds of fibers that stimulate what kinds of fibers?
visceral nerous/motor system. have motor fibers that stimulate smooth muscle and modified cardiac tissue
The efferent nerve fibers of the ANS are subdivided into…
the parasympathetic and sympathetic NS
how do impulses travel the sensory and somatic motor system between the CNS and effector organs compared to the conduction of impulse from the CNS to effector organs in the ANS?
in the sensory and somatic, they travel on a single neuron, whereas the the ANS they travel on two neurons.
What are the two nerves in the sympathetic ANS and their locations.
the presynaptic (pre ganglion) neurons that are in the grey matter of the CNS. Its fibers only synapse not he cell body of postsynaptic (post ganglionic) neurons, whose cell bodies are located outside the CNS in automatic ganglia, and fibers terminate on the effector organs (smooth muscle, cardiac or glands)
Cell bodies of the presynaptic neurons of the sympathetic division of the ANS are found in one location, which is
intermediolateral cell columns (nuclei of the spinal cord).
The cell bodies of postsynaptic neurons of the sympathetic ANS are found in two locations
paravertebral ganglia and pre vertebral ganglia.
Where do the axons of presynaptic neurons leave the spinal cord and where do they enter?
They leave through the anterior roots and enter thorough the anterior rami of the spinal cord (T1-L2).
Where do all presynaptic sympathetic fibers pass through?
the white rami communicates
Postsynaptic sympathetic fiber pass through?
grey rami communicantes
the postsynaptic sympathetic fibers that stimulate the contraction of blood vessels, arrestor muscles, cause sweating (in the head) all have cell bodies in the _____ and pass from the ganglion by means of _____.
superior cerival ganglion and cephalic arteries ramus.
Splanchnic nerves convert what?
visceral efferent (Autonomic) and afferent fibers to and from the body cavity.
cardiopulmonary slpanchnie nerves
thoracic cavity, heart longs and esophagus POSTSYNAPTIC
ABDONIMOPELVIC SPLANCHNIE NERVES
stomach and intestine, PRESYNAPTIC
presynaptic parasympathetic nerve bodies are located in what spots of the CNS
in the cranial parasympathetic outflow (cranial nerves 3,8,9,10). and in the sacral parasympathetic outflow (S2-S4 nerves)
The ENS. what two parts and where
enteric nervous system, has two interconnected plexus within the walls of the GI tract (myenteric plexus and the submucosal plexus)
Both the sympathetic and the parasympathetic systems innervate what kinds of structures?
involuntary
primary role of the parasympathetic ANS
homeostatic or anabolic, allowing the body to maintain quiet and orderly processes
primary role of the sympathetic ANS
prepare the body for fight or flight, catabolic. regulate blood vessels
