nervous system Flashcards
what are the 3 functions of the NS
- senses: detects a change
- integrates: input received, decision is made, command is sent
- responds: effector organs respond
how is the nervous system divided
into the central and peripheral NS
what does the central nervous system consist of?
- brain
- spinal cord
the central nervous system functions as?
a control center
the peripheral NS consists of what
neural tissue outside of CNS:
- receptors
- ganglia
- nerves
- motor nerve endings
the PNS functions as?
the link to and from the outside (efferent and afferent path)
the PNS is subdivided into what?
somatic and autonomic division
what is grey matter?
group of cell bodies of neurons, neuroglia and unmyelinated processes
what is white matter?
myelinated axons
what are other words used to describe white matter
- nerves
- tracts
- columns
what are nerves
bundles of axons
what are tracts
bundles of axons that share a common origin, destination or function
what are columns
groups of tracts
what are other words used to describe gray matter
- center/nucleus
- cortex
- ganglion
what is a center/nucleus
- group of cell bodies with a common function
- found in the CNS
what is a cortex
- outer layer of gray matter
- in CNS
what is a ganglion
- clusters of cell bodies
- outside the CNS but inside the PNS
what are the organs of the NS
- brain
- spinal cord
- nerves
- sensory receptors
what is an ascending tract/path
- sensory path
- going from PNS to CNS (UP towards brain)
what is a descending tract/path
- motor path
- going from CNS to PNS (DOWn towards body)
what structures protect the CNS (in order)
- bones
- meninges
- cerebrospinal fluid
- glial cells
- cellular barriers
how does bone protect the CNS
- makes up the vertebral column and skull
- protects from blows or bumps
what are meninges and how many are there?
- 3
- membrane wrappings between bone and nervous tissue
what is the outer layer of the meninge
- dura mater
describe the dura mater
- thick and tough
- made of dense irregular tissue
what is the second meninge called
arachnoid mater
describe the arachnoid mater
- thin covering made of cells, collagen and elastic fibers
what is the innermost layer of the meninge
pia mater
describe the pia mater
- made of squamous and cuboidal cells
- adhered to the surface of the spinal cord and brain
what are the spaced formed by the meninges
- epidural space
- subdural space
- subarachnoid space
what are the functions of the meningeal layers
- form protective wrappings
- carry nerves and blood vessels
- form attachment sites
- form spaces that holds fluid or fat
where is the epidural space located
- between the vertebra and the dura mater
what is found in the epidural space
fat
where is the subdural space found
between dura and arachnoid layer
what is held in the subdural space
- fluid that adheres the dura to the arachnoid (creates double membrane)
where is the subarachnoid space found
between the arachnoid and pia mater
what does the subarachnoid hold
the cerebrospinal fluid
what layers differ between the spinal cord and brain
brain contains the dura sinuses, which hold veins
spinal cord contains the epidural space, which holds fat
what is the function of the blood brain barrier
- filters and adjusts the nutrients and ions that pass through towards the brain
what makes up the structure of the blood brain barrier
- foot processes of astrocytes
- blood vessel wall made of simple squamous epithelial
what is cerebrospinal fluid (CSF)
clear, colorless liquid made of of water and chemicals from blood
what is the function of CSF
- aids in maintaining environment around neurons
- cushions –> subarachnoid space
- reduces the weight of brain by letting the brain float in it
- provides nutrients to cells lining the path of circulation
describe the circulation of csf
- choroid plexus
- lateral interventricular ventricle
- third ventricle aqueduct
- 4th ventricle
- central canal
- medial and lateral apertures
- SAS
- arachnoid vili
- dural sinuses
what is an arachnoid vili
one way valves in SAS that return CSF to blood by using the dural sinuses
how is csf produced
- formed from blood by choroid plexus
what are choroid plexus
- 2 layer cell wall consisting of blood capillaries and ependymal cells
- found in ventricle walls
- filters and adjusts blood plasma
how is csf removed
- absorbed into blood by the arachnoid vili via the dural sinuses
what’s the difference between blood, CSF and IF
blood
- contains higher protein and glucose levels than CSF
- contains rbc, wbc, etc
IF
- contains immune cells
what are the regions of the spinal cord from top to bottom
cervical
thoracic
lumbar
sacral
what is a plexus
branching and merging of PNS nerves that form a network of axons from the spinal cord
what is the function of a plexus
- ensure info to and from limbs is carried by multiple paths
- ensures that if a plexus is injured, the function to that area isn’t lost
what are the type of plexuses
cervical
brachial
lumbar
sacral
what is the conus medullaris
the tapering region of the spinal cord
what is the terminal filum
end point of the spinal cord
what are cauda equina
group of nerves that travel down the spinal cord before exiting
what are dermatomes
specific segment or area of skin that is supplied by a single nerve
what structures of the spinal cord are found in the cross sectrion
white matter
grey matter
horns of the grey matter
dorsal root ganglion
dorsal and ventral root
nerve
rami
what is the dorsal root ganglion
cell bodies of unipolar sensory neurons
what is a dorsal root
axons of sensory neurons that bring info to spinal cord
what are ventral roots
axons of motor neurons
- carry info away from spinal cord to muscles and glands
what are rami
branches distal to spinal nerves
what are horns
projections of grey matter of spinal cord
what is a spinal nerve
fusion of dorsal and ventral roots that contain motor and sensory information
what are the 2 functions of the spinal cord
- highway for ascending and descending tracts linking the PNS to CNS
- control center for reflexes
what is a commissure
connection between the left and right sides of the grey matter of the spinal cord
what is the lateral/medial corticospinal
- skeletal muscle movement of hands and body
- part of 2 neuron path for conscious control of skeletal muscles
what are dorsal white columns
2 neuron path of sensory info of touch and pressure
what is a reflex
automatic, involuntary response to a stimuli
what are the characteristics of all reflexes
- rapid
- involuntary
- predictable response
- can be innate or learned
what is a reflex arc
the path of nerve impulses from stimuli to response
what are the components of the reflex arc
- receptor
- afferent path
- control center
- efferent path
- effector
what is the receptor of the reflex arc
dendrite ending of a sensory neuron
what is the afferent path of the reflex arc
dendrite/axon of the sensory neuron in the nerve and dorsal root
what is the control center of the reflex arc
synapse or interneuron in the gray matter
what is the efferent path of the reflex arc
axon of the motor neuron in the ventral root and nerve
what is the effector of the reflex arc
muscle or gland
what is the stimulus, response, pathway and role of the stretch reflex
stimulus: inc in muscle length detected by muscle spindle
response: contraction
path: 2 neuron reflex arc
role: regulates muscle length
what is the stimulus, response, pathway and role of the withdrawal reflex
stimulus: pain
response: withdrawal (flex)
path: 3 neuron reflex arc
role: withdrawals limb from stimulus
whats the different between monosynaptic and polysnyaptic
mono: one synapse
poly: 2+ synapses
what the difference between ipsilateral and contralateral
ip: motor response occurs on the same side of the body to stimulus
cont: motor response occurs on opp sides of the body to stimulus
the cervical plexus supplies which part of the body
neck and thoracic cavity
the brachial plexus supplies which parts of the body
upper limbs
the lumbar plexus supplies which part of the body
lower limbs
the sacral plexus supplies which part of the body
lower limbs
what are cranial nerves
nerves that originate in the brain stem
what is the effector of the somatic NS
skeletel muscle
what is the effector of the ANS
smooth and cardiac muscles
what is the control center of the somatic NS
cerebral cortex
what is the control center of the ANS
hypothalamus
what is the neuron path of the somatic NS
2 motor neuron path –> 1 in PNS
what is the neuron path of the ANS
3 motor neuron path –> 2 in PNS
what is the NT of the somatic NS
ach
what is the NT of the ANS
ACH and epinephrine (E)
the ANS splits into2 subdivisions, what are they
parasympathetic and sympathetic
what the difference between preganglionic and post ganglionic
pre: before the ganglion
post: after the ganglion
what is a terminal ganglion
ganglion near or within the effector organ
what is a sympathetic chain
ganglion chain near the spinal cord
the sympathetic NS originates where?
spinal cord
the sympathetic has a – pre ganglion and a — post ganglion
short, long
the sympathetic NS contains a sympathetic ganglion chain. What is that?
paired bundle of nerves that extend from the base of the skull
the sympathetic NS is responsible for what?
- prepares body for action and motion
- responsible for fight or flight reaction
- exercise, emergency and emotions
is the sympathetic NS catabolic or anabolic
catabolic
where is the SNS located
thoracic lumbar regions
the SNS innervates what parts of the body
trunk and limbs
what’s the affect of the SNS
- widespread because highly branched
- long lasting: because epinephrine is released into blood stream
when SNS is activated, what are the main things that occur (scared cat)
- inc HR and BP
- glucose is released for energy (mobilizes energy reserves)
- inhibits digestive and urinary tract
- adrenal medulla releases epinephrine
the parasympathetic NS originates where?
spinal cord
the para NS has a — preganglion and a — post ganglion
long, short
is the pars NS anabolic or catabolic
anabolic
the parasympathetic NS is responsible for what actions?
- rest and digest response that conserves energy
the para NS is located where
cranial and sacral regions
the para NS innervates what?
viscera
what NT are used by the para NS
ach
describe the effects of the para NS
- localized
- short lives due to minimal branching
when para NS is activated, what occurs to your body
- heart slows
- constricts bronchioles
- contracts urinary bladder
- digestive tract is stimulated
the SNS releases what NTs at the post and preganglions
ACH at pre
E at post
the para NS releases what NTS at the post and pre ganglions
ACH at pre
ACH at post
what does dual innervation mean
an organ is innervated by both the sympathetic and parasympathetic systems
