Nervous System Flashcards
What are the two divisions of the Nervous System?
Central NS
Peripheral NS
What is the ”command centre” of the brain? What is it composed of?
-Central NS
-brain and spinal cord
What does the PNS consists of?
cranial and spinal nerves
What are the two divisions of the PNS
sensory/afferent division
motor/efferent division
What is the afferent division?
It is a division that has sensory receptors that detect stimuli
What is the efferent division?
It is a division that convey impulses from CNS and conducts a response to a stimulus.
How do the nerves covey impulses from the CNS?
away
difference of somatic and autonomic?
somatic is voluntary movement of skeletal muscles while autonomic is involuntary movement of the smooth and cardiac muscle (meaning we cannot control it)
what is sympathetic? what is parasympathetic?
-fight or flight
-rest and digest
Are neurons able to undergo mitosis? Why or why not?
No because they are amitotic. They are irreplaceable.
What does the RER of a neuron called?
Nissl Bodies
What do you call the clusters of cell bodies in the CNS? What colour are they?
Nuclei, a gray matter
What do you call the clusters of cell bodies in the PNS?
ganglia
What is the function of dendrites?
Receive incoming messages and relay it to the cell body.
What is the function of an axon?
carry impulses away from the cell body
What is the axon hillock?
where the axon meets the cell body
what does the axon terminal look like?
typically branched with synaptic end bulbs
What does it mean when an axon is myelinated?
wrapped in many layers of cell membrane
What are Schwann Cells?
cell membrane from PNS
What are oligodendrocytes?
cell membrane from CNS
What do myelin sheaths provide?
electrical insulation
What are the “Nodes of Ranvier”?
gaps in myelin sheath
What do you call the myelinated axon bundles in CNS? PNS?
CNS- tracts (white matter)
PNS- nerves
What are Neuroglia(s)?
Glial cells that support neuron cells
Can glial cells undergo mitosis? If so, what can it be prone to?
Yes. They are prone to brain tumors
What are the 4 types of CNS neuroglia?
-oligodendrocytes
-microglia
-astrocytes
-ependymal
List the functions of the 4 types of CNS neuroglia.
1)Oligodendrocytes- produce myelin around axon
2)Microglia- protection that can become phagocytic if detect unusual neurons
3)Astrocytes- surround blood capillaries to form Blood Brain Barrier
-control capillary permeability
4)Ependymal-neural epithelia
-line brain ventricles and central canal of spinal cord
What are the 2 types of PNS neuroglia?
Schwann cells and Satellite cells
What are Schwann cells?
form myelin around axons in PNS
What are Satellite cells?
surround neuron cell bodies in ganglia-protection and support
What is a unipolar neuron?
1 process that divides into two: central and peripheral
the peripheral end has dendrites which are sensory neurons—remainder is axon
What is a bipolar neuron?
has 2 processes: 1 axon and 1 process with dendrites
sensory: retina, smell (olfaction)
What is a multipolar axon?
3 or more processes: 1 axon, many dendrites
all interneurons + motor neurons
What type of neurons are sensory/afferent neurons?
mostly unipolar
from sensory receptors to CNS
What kind of neuron are interneurons? Where are they found?
mostly multipolar and within CNS
How are neurons classified?
Structure/Anatomy
Function (based on direction of impulse conduction)
What are the three types of Neuron Junctions? Explain each.
Neuronal Junction- neuron to neuron and can be either chemical (neurotransmitters) or electrical (ions)
Neuromuscular Junction- motor neuron to skeletal muscle
Neuroglandular Junction- motor neuron to gland
What is the most common type of Neuronal Synapses?
Chemical
List the 4 structures of a chemical synapse and explain each briefly.
- Presynaptic Neuron- neuron bringing the impulse
- Axon Terminal- has synaptic end bulbs; inside the end bulb are synaptic vesicles that contain neurotransmitter)
- Synaptic Cleft- spaces between neurons
- Postsynaptic Neuron- receives the impulse and has a postsynaptic membrane
What are meninges?
Connective tissue around the brain and spinal cord.
What is the outer layer of the meninges called? How many layers does the brain have? The spinal cord
?
dura mater, 2 fused layers, 1 layer
What do you call the space in between the 2 fused layers of dura mater in the brain? What do they contain?
Venous sinuses. They contain blood
What do you call the space that is deep to the dura matter? What is it filled with?
subdural space; ISF
What do you call the superficial space to dura mater? Where can it be only found?
epidural space and can only be found in the spinal cord
What is the epidural space filled with?
fat, blood vessels, CT, etc.
What is the arachnoid mater
The middle layer of the meninges
Is the arachnoid mater vascular or avascular?
avascular
The subarachnoid space contains 2 things. What are they?
- Cerebrospinal fluid
- web-like strands of CT to secure it to pia mater below
Where can you only find the arachnoid granulations? Where does it project into?
brain; dural sinuses
What is the inner layer of the meninges called? Where can it be located?
pia mater; surface of brain and spinal cord
is the pia mater vascular or avascular?
vascular
Where can the CSF be located?
surrounds brain and spinal cord
brain ventricles + central canal of the spinal cord
Where in the lateral ventricles can the CSF be located?
cerebrum
Where in the 3rd ventricles can the CSF be located?
diancephalon
Where in the 4th ventricle can the CSF be located?
surrounded by pons, medulla oblongata, cerebellum
What is the function of CSF?
to cushion CNS- brain buoyant
Where is the CSF formed? Where is it produced?
blood plasma; choroid plexuses (blood capillaries) in each ventricle
CSF circulation
l
What are the two cell types of the blood brain barrier? (BBB)
- endothelial cells (of capillaries) with tight junctions
- astrocytes- foot processes wrap around endothelial cells
Describe astrocytes.
selectively permeable: allows glucose, fat soluble material
does not allow toxins, antibiotics, etc.
What is the Cerebral Arterial Circle
cerebral arteries that form a circle at base of forebrain
What gland does the Cerebral Arterial Circle encircle?
pituitary gland + optic chiasma
What does the Cerebral Arterial Circle unite?
two major blood supplies to the brain, anterior and posterior
Blood flow to brain (anteriorly)
Blood flow of the brain (starting from internal carotids)
Blood return from Brain
What are the parts of the brain?
forebrain
diencephalon
midbrain
hindbrain
List the 5 lobes of the cerebrum.
frontal
temporal
parietal
occipital
insula- deep into temporal lobe
what are fissures?
deep grooves
What are the three types of fissure?
longitudinal fissure
transverse fissure
lateral fissure
what does the longitudinal fissure separate?
separates right and left cerebral hemispheres
What does the transverse fissure separate?
separates cerebellum and cerebrum
What does the lateral fissure separate?
temporal lobe from the rest of cerebrum
what are gyri?
ridges
list 2 types of gyri and what lobes they are located
postcentral gyrus- parietal lobe
precentral gyrus- frontal lobe
what are sulci?
shallow grooves
what do sulci separate?
gyri
What are the functional areas of cerebral cortex?
motor areas
sensory areas
association areas
where can the motor area be found?
frontal lobe
What does the motor area control?
skeletal muscle movement
What are the three regions of the motor area?
primary motor area (precentral gyrus)
premotor area
Broca’s area (motor speech)
List the 4 sensory areas of the cerebral cortex
general sensory area (pain, touch, temp, pressure)
vision
auditory and olfaction
taste + visceral (sensation
Where are each of the sensory areas found?
general sensory area = postcentral gyrus in parietal lobe
vision = occipital lobe
auditory + olfaction = temporal lobe
taste + visceral = insula
where can association areas be found?
parietal, occipital, temporal lobes
What do association areas do?
recognize info from memories
what are tracts?
white matter
What are the 3 types of tracts?
association tracts
commissural tracts
projection tracts
Where can each tracts be found?
association tracts: from gyrus to gyrus of the same hemisphere
commissural tracts: gyrus to gyrus of opposite hemispheres
projection tracts: run vertically (brain and spinal cord)
What are basal nuclei and what do they control?
paired masses of gray matter “within” white matter; control skeletal muscle movement
Is the diencephalon gray or white matter?
gray
What consists of the the diencephalon?
thalamus and hypothalamus
what is the thalamus made out of?
2 lobes connected by intermediate mass (bridge through 3rd ventricle)
What is the function of the thalamus?
relay station for impulses coming to cortex from the spinal cord
Where can the hypothalamus be located?
inferior to thalamus and above pituitary
What is the hypothalamus’ function?
major regulator of the internal environment (visceral control)
what does the midbrain connect?
pons + diencephalon
what does the midbrain contain?
cerebral aqueduct
The anterior portion of the midbrain has projection tracts called _________________________.
cerebral peduncles
The posterior portion of the midbrain has _____ nuclei which are called ______________________.
4; corpora quadrigemina
The 2 superior colliculi are for what?
visual reflexes
the 2 inferior colliculi are for what?
hearing
what does the hindbrain consist of?
pons, medulla oblongata, cerebellum
Where can the pons be found?
anterior to cerebellum
Where can the tracts of pons be found?
b/w brain and spinal cord + tracts to/from cerebellum
what are pons
pontine respiratory centres
where is the medulla oblongata
inferior to pons and ends at foramen magnum
What are the two bulges of the medulla oblongata called? what kind of tracts are they?
pyramids; large motot tracts
what is decussation
crossover of pyramids just above the spinal cord
what are the three vital centres in the medulla
cardiac
vasomotor (blood vessels)
respiratory
what are the several non-vital centres for?
swallowing, sneezing, vomiting
what is the brainstem composed of?
midbrain, pons, medulla oblongata
where can the cerebellum be found?
posterior to pons/medulla
what are the folds of the cerebellum called
folia
the cortex of the cerebellum is what colour
gray
what is the white matter of the cerebellum called
arbor vitae (deep to cortex and anterior to cerebellum)
what is the function of the cerebellum?
coordinates skeletal muscle contraction for balance and posture
what are the two functional systems of the cerebellum?
limbic system
reticular formation
where can the limbic system be found
nuclei in cerebral hemisphere + diencephalon
what does the limbic sys regulate
emotions
what does the limbic system contain
areas involved in memory
where can the reticular formation be found?
nuclei in brain stem
what parts of the brain does the reticular formation involve
cortex, thalamus, hypothalamus (together form Reticular Activating System RAS)
what does the reticular formation regulate?
alertness and attention; also filters stimuli and only sends new/unusual signals to other brain areas
what results when reticular formation is inhibited? what about if damaged?
sleep; coma
The spinal cord is from the foramen magnum to?
L1/L2 (conus medullaris)
the nerves from the spine continue down through the vertebral foramina as?
cauda equina (horse’s tail)
where does the nerves from the spinal cord exit?
intervertebral foramina
what is the CT extension of pia mater? (it is also where CSF samples are taken)
filum terminale
what separates cord into right and left halves
anterior median fissure and posterior median sulcus
what does the central canal contain
CSF
What is the gray matter made up of?
cell bodies, dendrites of motor neurons + interneurons
what is the shape of the gray matter?
H
cross bar = gray ____________
commissure
what are the 3 horns of the gray matter and what are they for
dorsal horn = sensory
lateral horn = motor
ventral horn = motor
What is the white matter composed of?
myelinated axons containing ascending (sensory) or descending (motor) tracts
what 3 columns does the white matter form
dorsal column
lateral column
ventral column
What are the functions of the spinal cord?
- sensory + motor impulses
- reflexes
What are the 12 Cranial Nerves
I.Oh- Olfactory
II. Once- Optic
III. One- Oculomotor
IV. Take- Trochlear
V. The- Trigeminal
VI. Anatomy- Abducens
VII. Final- Facial
VIII. Very - Vestibulocochlear
IX. Good- Glossopharyngeal
X. Vacations- Vagus
XI. Are- Accessory
XII. Had- Hypoglossal
What 2 pairs of cranial nerves are for sensory only?
I & II
What pair of cranial nerves are “mainly” sensory
VIII
How many pairs are mixed nerves? What do they carry?
9; sensory and motor neurons
motor neurons have cell bodies in?
brainstem nuclei
sensory neurons have cell bodies in?
ganglia
how many pairs of nerves are in the spinal nerves?
31 pairs of mixed nerves
list the 31 pairs of spinal nerves
8 cervical
12 thoracis
5 lumbar
5 sacral
1 coccygeal
where do the spinal nerves exit? what is excluded?
intervertebral foramina; 1st (between atlas + occipital)
what are the 2 points of attachment of the spinal nerves to the spinal cord?
dorsal root and ventral root
What is the dorsal root
sensory neurons; cell bodies in dorsal root ganglion
what is the ventral root
autonomic and somatic motor neurons; cell bodies in ventral or lateral horn
what does the spinal nerve join?
dorsal and ventral roots
what are the branches of the spinal nerve called>
rami
what is the dorsal ramus
innervate skin + muscles of the back
what does the ventral ramus form
thoracic nerves OR further branch and join up forming nerve plexuses
what is the important nerve arising from cervical?
phrenic
what are the important nerves arising from brachial?
axillary, radial, ulnar, median, musculocutaneous
what is the important nerve arising from lumbar?
femoral
what is the important nerve arising from sacral? what does it divide into?
sciatic—tibial and common fibular
what does the rami communicates contain
autonomic nerve fibres
what does the rami communicantes connect
ventral ramus (spinal nerve) to sympathetic trunk
what are the CT wrappings of a nerve (3)
epineurium
perineurium
endoneurium
what is wrapped around the whole nerve
epineurium
what is wrapped around the fascicles
perineurium
what is wrapped around the axon + myelin
endoneurium
What does the sensory (afferent) division do?
stimulu to receptor to CNS
what do receptors do?
detect changes in the environment
what are the 3 classifications of receptors
exteroceptors
interoceptors
proprioceptors
what are exteroceptors?
stimulus in external env. = receptors at body surface
what are interoceptors
stimulus in internal env.
what are proprioceptors? where are they located?
monitor body position; joints, skeletal muscles, etc.
What are the 5 types of stimulus received
mechanoreceptors
thermoreceptors
nociceptors
chemoreceptors
photoreceptors
What is the structure of the general senses’ receptor
free nerve endings or encapsulated endings
what are free nerve endings
terminal dendrites of unipolar sensory neurons
what are encapsulated nerve endings
terminal dendrites enclosed in CT (ex. corpuscles)
What are First Order Neurons
unipolar neuron attached to a receptor
where does the axon travel in FON
cranial/spinal nerves to CNS
where are the cell bodies located in FON
sensory ganglia of cranial nerves
dorsal root ganglia of spinal cord
where are the axon terminals of FON
brain
dorsal horn of spinal cord
what is the function of the motor (efferent) division
CNS to effector
What are the 2 subdivisions of the Efferent D.
somatic and autonomic (ANS)
what is the effector of the somatic? of the ANS?
skeletal muscles; smooth/cardiac muscle, glands
what does the somatic subdivision consists of
lower motor neurons: single multipolar neuron
where are the cell bodies of the somatic subdivision found
ventral horn of spinal cord to effector
motor nuclei of brainstem to effector
what type of neurons are in the ANS
2 successive multipolar neurons from CNS to effector: pre- and post- ganglionic neuron
difference of pre ganglionic to post ganglionic neuron
pre: myelinated, cell body in brain stem or lateral horn of spinal cord
post: unmyelinated, cell body in autonomic ganglion (outside CNS)
2 subdivisions of the ANS
sympathetic
parasympathetic
difference of SNS to PSNS
What are the two pathways of the Nervous system
Ascending (sensory) and Descending (motor)
What is the function of the ascending pathway
conduct impulses from general sense receptors into brain
what are the 3 successive neurons from receptor to cortex
First order neuron
Second order neuron
3rd order neuron
FON
receptor to spinal cord (PNS)
2nd ON
interneuron, multipolar (CNS)
cell body in dorsal horn of spinal cord or medulla
3rd ON
interneuron, multipolar
cellbody in thalamus- impulses to postcentral gyrus (sensory cortex) (CNS)
the axons of the 1st and 2nd order neurons form what
ascending spinal tracts
What are the 3 ascending spinal tracts?
Dorsal (Posterior) Column Pathway
Spinothalamic Pathway
Spinocerebellar Pathway
Describe Dorsal Column Pathway
sensations can be precisely located
receptors: free nerve endings; Meisner’s, etc.
Describe Spinothalamic Pathway
non-specific, difficult to localize
receptors = temp and pain
Describe Spinocerebellar Pathway
ascending tracts from spinal cord to cerebellum
receptors = proprioceptors
2nd ON direct to cerebellum (no 3rd ON) therefore no conscious perception and no decussation
What is the function of the Descending Pathway
conduct impulses from brain to effector
What are the 2 neuron pathway of the Descending Pathway
Upper Motor (CNS) and Lower Motor Neuron (PNS)
axons of the upper motor neurons form?
descending spinal tracts
what are corticospinal tracts
cell bodies in cerebral cortex
tracts mainly decussate in medulla
what are indirect tracts
cell bodies in brainstem nuclei
receive impulses from motor cortex, basal nuclei, cerebellum
