Nervous System Part 1 Flashcards
focuses on the strucutre of the body
Anatomy
how the body parts function together
physiology
Receives information, processes information, and sends out signals to the muscles and glands to elicit an appropriate response
integrates and controls other systems of the body
The nervous system
responsbile for commuincation btw cells by forming a system of electrical impulses that communicate very rapidly
nervous tissue
one of the two main dvisions that includes the brain and spinal cord, which lie in the midline of the body
sends signals/impulses to receive impulses from the PNS
central nervous system
protects the brain
skull
protects the spinal cord
vertebrae
collections of cell bodies inside the CNS
nuclei
collection of nerve axons in CNS
tracts
includes all nerves not in the brain nor spinal cord
includes cranial and spinal nerves
can be divided into sensory/afferent division and motor/efferent division
peripheral nervous system
region that includes the mdbrain, pons, and medulla
brainstem
- project from the brainstem
- innervate the face, head, and neck
cranial nerves
- poroject from the sides of the spinal cord
- spread out to innervate the rest of the body, trunk and extremities
spinal nerves
collections of cell bodies in the PNS that are grouped together in masses
part of a single nerve
ganglia
collection of nerve axons in the PNS
nerves
receives impulses from sensory organs via the afferent division
relays signals/impulses from CNS to muscles and glands via the motor/efferent division
PNS
relays impulses from CNS to muscles and glands
can be divided into the somatic nervous system and the autonomic nervous system
efferent/motor division
-nerves are generally under conscious/voluntary control
controls movement of the skeletal muscles, skin, and joints
somatic nervous system
under unconscous/involuntary control
controls glands and smooth muscles of internal organs
can be divided into 2 systems: sympathetic and parasympathetic nervous system
autonomic nervous system
activates and prepares body for emergencies, stress and vigorous muscular activity
sympathetic nervous system
operates during normal situations, permits digestion and conserves energy
parasympathetic nervous system
nerve cells that conduct electrical impulses and relay info throughout the body
contain dendrites, cell body and axons
they do not undergo mitosis (Cell division)
can survive a persons entire lifetime; any damage to one cannot be replaced
can survive just minutes w/o O2
neurons
synthesizes all nerve cell products
has a large nucleus w/ surrounding ctyoplasm containing organelles; but no centrioles
one of the main functions is to make neurotransmitters
neuron cell body
receiving end of a neuron
numerous short extensions that emanate from cell body that receive info from other neurons and conduct nerve impulses toward cell body
dendrites
conducts nerve impulses away from cell body to axon terminals
can vary in length being short to up to 3 ft long
made of cell components like cell body but lack rough ER
depends upon cell body to send proteins needed down it
can regrow in PNS under certain circumstances
axon
chemicals stored inside secretory vesicles at teh end of axon terminals
emmited across a synapse to the dendrite of another neuron
sent from a presynaptic neuron through synapse to postsynaptic neuron
neurostransmitters
secretory vesicles where neurotransmitters are stored inside a neuron cell body
axon terminal vesicles
is a gap btw 2 neurons witoout physically touching one another
synapse
neuron before the snyapse
sending neuron
presynaptic neuron
is a neuron found after synapse
receiving neuron
postsynaptic neuron
have 3 or more extensions from the cell body, one axon and many dendrites
can be called motor neurons
multipolar neuron
have a central cell body w/ 2 extensions
found within the body as special receptor cells in visual and olfactory systems
bipolar neuron
have 1 extension off cell body that branches into 2: 1 central process running into the CNS and another peripheral process running into sensory receptor
unipolar neurons (pseudounipolar)
are unipolar and function to carry info from PNS to CNS
most cary impulses from the skin or internal organs to CNS
sensory (Afferent) neurons
found only in CNS
typically multipolar neurons that transmit impulses within different parts of the CNS
Interneurons
are multipolar neurons that send messages from CNS to PNS
Motor neurons
consists of hundreds of thousands of axons wrapped in a connective tissue
a nerve
highly important for neuron function
are support cells for neurons to enable them to thrive in needed environment
cells include ependymal, oligodendrytes, astrocytes and microglial cells
neuroglial cells
short sections in which the peripheral nerve axon is coated
special type of neuroglial cell found in PNS that are composed of myelin sheaths
loosely associated with axon; not continuously
Schwann cells
white fatty layers that are rolled around the axon to insulate nerve fibers and increase the speed of nerve impulses
myelin sheath
are gaps btw Schwann cells where nerve impulses are forced to jump from one to the next
nodes of Ranvier
when a nerve impulse is forced to jump to the next node, greatly increasing the nerve impulse transmission along the axon
saltatory conduction
surround cell bodies of peripheral neurons that help to regulate cell body environment
satelite cells
process of peripheral nerves regenerating the axon length
axonal regeneration
circulate cerebrospinal fluid and allow fluid exchange btw brain, spinal cord and CSF
ependymal cells
is a clear fluid that only circulates the brain and spinal cord
CSF
act as insulation for CNS axons
oligodendrocytes
control chemical enviroment of neurons by wrapping around blood capillaries by blood brain barrier
astrocytes
physical barrier that allows passages of only certain substances into CNS by astrocytes
blood brain barrier
protect the CNS by scavenging dead cells and infectious microorganisms
microglial cells
neurons are specialied to conuduct electrical impulses called what?
is the change in polarity when an axon is stimulated to conduct a nerve impulse
due to special protein-lined channels in the membrande that can open to allow either sodium or postassium ions to pass through
these are self-propagating b.c ion channels are prompted to open when membrane potential depolarizes (decreases)
action potentials
when an axon’s plasma membrane is at rest, meaning that one side has a different charge than the other
polarized
when the axon is not conducting an impulse, the difference in electrical charge is called?
this is equal to about -70mV
the charge is negative b/c the charge on the inside of the axon’s cell is less than the outside membrane
both sodium and potasssium gates are closed
resting potential
maintains resting potential and uses active transport to carry ions across the plasma membrane
it works by using an integral carrier protein that, for every three sodium (Na+) ions pumped out, two potassium (K+) ions are pumped in
must keep in constant operation because the Na+ and K+ ions will naturally diffuse back to where they originated
a positive charge is maintain outside b/c because more Na+ ions are being pumped outward than K+ pumped inward due to permeable membrane
sodium-potassium pump
second phase of an action potential
sodium gates open and sodium rushes into axon
voltage travels to 0 and increases up to +40mV
depolariation
when the potential returns to normal after being depolarized, indicating that the inside of the axon is negative again
Sodium gates close and potassium gates open to allow potassium out of axon
returns a negative voltage inside of axon
repolarization
special protein-lined channels that can open to allow either sodium or potassium ions to pass through
are voltage activated as proteins respond to changes in voltage w/ changes in shape
sodium and potassium gates
phase 4 of action potential
potassim gates are slow to close and there is an undershoot of potential
voltage drops below -70mv and then returns back to -70mV as resting state
afterpolarization, aka hyperpolarization
an action potential is either occuring or not
intensity of a sensation (minor or major pain) is distinguished by the number of neurons stimulated and the frequency with which the neurons are stimulated
all-or-nothing principle
the transmission of nerve impulses is?
neurotransmitters (Chemicals) allow the signal o jump synaptic gap, which moves from electrical (through the neuron) to chemical (in the synapse) to electrical again once the signal reaches the next neuron
electrochemical
when a nerve impusle reaches the end of an axon, voltage gated…
calcium channels open to allow calcium to rush in and cause the vesicles w/ neurontransmitters to fuse w/ plasma and release neurotransmitters in synapse
is an enzyme that breaks down the neurotransmitter acetylcholine
contained by synpases
acetylcholinesterase (cholinesterase)
prevention of continuous stimulation of neurotransmitters
inhibition
neurotransmitters made by adrenal glands
epinephrine and norepinephrine
is a neurotransmitter found at neuromuscular junction in PNS
this is released into the synapse when the nerve impulse reaches the muscle fiber at NMJ
binds to receptors on muscle fiber to cause sodium channels to open
Acetylcholine
is a special type of snyapse formed btw a motor neuron and muscle tissue
nervous system interacts with musuclar system here to allow muscular contraction
neuromuscular junction (NMJ)
is a specialized type of smooth ER found in striated muscle tissue
sodium rushes out of channels from a muscle cell that triggers an action potential, which reaches here
-calcium ions released here causes the muscle to contract
sarcoplasmic reticulum
instantaneous, automatic and involuntary motor responses in a nervous system
come in a variety that start from stimuli occuring inside or outside the body
some involve the brainstem (eyeblinking)
reflexes
subconscious examples of a reflex
regulation of blood sugary bu hormones
conscious examples of a reflex
shivering in response to low temp; withdrawing hand from a hot object
reflexes that involve the spinal nerves and spinal cord without waiting for processing by brain
refers to the neural pathway that a nerve impulse travels
i.e. flexor-withdrawal reflex
helps an organism avoid injury by providing an immediate withdrawl from dangerous stimuli
reflex arc
where sensory info travels into the spinal cord from
contains the axons of sensory neurons
dorsal root
motor info ravels out of spinal cord via here
motor neurons (Axons) leave spinal cord here
ventral root
contains the cell neuron bodies (interneurons) in the spinal cord
gray matter
contains the axons of neurons in the spinal cord
surrounds the gray matter of spinal cord
white matter
contains the cell bodies of sensory neurons
dorsal root ganglion
where sensory neurons synapse on cells, located on spinal cord in gray matter
posterior horn
motor neuron cell bodies are located in here of the gray matter
anterior horn
contains both sensory and motor neurons from the ventral and dorsal roots
spinal nerve
occur faster than conscious descion to move b/c electrical signal doesn’t have to travel to the brain and back
only travel to the spinal cord and back (which is much shorter)
i.e. flexor reflex and stretch reflex
spinal reflexes
what are the reflex arch pathways?
- The receptor at the end of a sensory neuron reacts to a stimulus.
- The sensory (afferent) neuron conducts nerve impulses along an afferent pathway towards the central nervous system (CNS).
- The integration center consists of one or more synapses in the CNS.
- A motor (efferent) neuron conducts a nerve impulse along efferent pathway from the integration center to an effector.
- Effector responds to the efferent impulses by contracting (a muscle) or secreting a product (a gland).
are a special type of muscle reflex that protects the muscle agains increases in length that can tear/damage muscle fibers
stretch reflexes
specialized uscle cells that are monitory the amount of stretch in a muscle
if a muscle becomes overstretched, it triggers a reflex to occur, which contracts muscle bak to correct length
muscle spindles
also called the knee jerk reflex used in doctors’ offices to test stretch of quadriceps femoris muscle in thigh
is an example of a stretch reflex
purpose is to prevent overstetching of quads
patellar reflex
attaches quads to tibia bone of lower leg
patellar tendon
a more complex neural pathway in which pain receptors in skin generate nerve impulses along dedrites twoard cell body of CNS in response to hot objects
impulses travel along axon of sensory nerve and synapse on internuerons in gray matter of spinal cord
excitatory interneurons send excitatory signals signals to motor neurons to cause muscular contractions
Inhibitory interneurons send inhibitory signals that prevent muscular contraction
occurs almost instanteaneosulsy b/c sensory neuron stiulates interneurons involved in relfex process before reaching the brain
flexor withdrawal reflex
The dorsal root of a nerve contains what type of neurons?
Sensory afferent neurons
The ventral root of a nerve contains what type of neurons?
motor efferent neurons
This part of the autonomic system increases digestion.
parasympathetic
A neuron going to the bicep of the forearm is part of the:
-PNS & Somatic system
Describe the synthesis and storage of neurotransmitters.
The neuron cell body manufactures neurotransmitters, which are stored in secretory vesicles at the end of axon terminals.
An afferent neuron carries information from:
from the PNS to CNS
Axons in which system are only capable of regeneration ?
Peripheral nervous system
At rest, a neuron plasma membrane is:
Polarized (around -70mV)
- Maintains the resting phase of an axon
- must remain in constant operation to maintain resting state
- for every 3 sodium ions pumped out, 2 k+ are pumped in
- the effect of the pump is negative inside membrane, but positive outside membrane
sodium-potassium pump
What prevents continuous stimulation of a nerve synapse and how is this accomplished?
The short existence of neurotransmitters in the synapse prevents continuous stimulation. Some synapses contain enzymes that rapidly inactivate neurotransmitters and other synapses rapidly absorb the neurotransmitter.
What neurotransmitter is found at the neuromuscular junctions?
acetylcholine
True or False: Action potentials travel in multiple directions within the same neuron.
False
n a reflex, the ____________ neuron conducts nerve impulses along a pathway to create a response.
motor (Efferent)
This part of a reflex is inside the CNS, made up of one or more synapses.
integration center
You touch a hot pan when cooking. List out the steps, in detail, of the nervous pathway of the reflex that occurs.
Flexor withdrawal reflex:
- Pain receptor in skin
- Sensory (afferent) neuron through DRG
- Interneurons in spinal cord:
- (1) Excitatory to biceps
- (2) Inhibitory to triceps
- Motor neurons: Contract biceps, inhibit triceps
- Action: Elbow flexion pulls hand away from flame.
Botulism is a disease caused by a neurotoxin that interferes with the release of Acetylcholine.
Patients with this disease experience flaccid paralysis, or the inability to contract their muscles. Explain why this would occur.
The nervous system interacts with the muscular system at NMJ.
Acetylcholine must be released from the presynaptic motor neuron into the synapse to bind onto the muscle fiber, causing a muscle contraction.
Withoutrelease of ACh, there won’t be interaction btw the nervous system and the muscular system - thus no muscle contraction.
is a special type of synapse formed between a motor neuron and muscle tissue.
NMJ
