Chapter 9 - Nervous System Flashcards
Describe the structure of the neuron
Axon, dendrite, perikaryon
Describe the function of neuron
Polarization and depolarization
Describe the functions of neuroglia
structural and functional support to neurons
Protection to neurons
Differentiate between white and gray matter
Gray contains most of the neuron cell bodies - very superficial in brain and deep in spinal cord
White contains most of the myelinated nerve fibers - deep in brain and superficial in spinal column
Describe the function of afferent nerves
Conduct impulses towards CNS
Also called sensory nerves
Describes the function of efferent nerves
Conduct impulses away from CNS
Also called motor nerves
List the components of the central nervous system
(Brain and spinal cord)
Main features
-neuron cell bodies
-myelinated and unmyelinated nerve cells
-Glia cells
White and gray matter
List the components of the peripheral nervous system
Somatic
-cranial nerves
-spinal nerves
Autonomic Nervous System
Differentiate btween autonomic and somatic nervous systems
Autonomic system
-Coordination of autonomic system
- digestive juices, heart rate, etc
Somatic System
-conscious or voluntary control of skeletal systems
Excitatory neurotransmitters
Usually cause influx of Na so postsynaptic membrane moves towards threshold
Acetylcholine
norepineprhine -fight or flight
epineprhine - fight or flight
dopamine - autonomic
Inhibitory neurotransmitters
Makes inside of cell more negative, moving the charge within postsynaptic membrane further from threshold
Acetylcholine
norepinephrine -fight or flight
dopamine
gamma-aminobutyric acid (GABA)
glycine
serotonin
endorphins
Describe the structures and functions of the cerebrum
learning and intelligence
largest part of brain in mamals
white and gray matter
two cerebral hemispheres divided by a longitudinal
surface covered with gyri separated by sutures and sulci (small grooves)
cerebral cortex
Describe the structures and functions of the cerebellum
white and gray matter
2nd largest part ofbrain
caudal to cerebrum
allows body to have coordinated movement, balance, posture and complex reflexes
Describe the structures and functions of the diencephalon
does not have clearly defined white and gray matter
passageway between brain and cerebrum
Temperature regulation, hunger, thirst, rage and anger
Thalamus - relay station for regulatory sensory inputs to cerebrun
hypothalamus = interface between nervous system and endocrine system
pituitary - endocrine master gland
Endocrine and nervous system compare and contrast
nervous system
uses chemicals to carry messages
- neurotransmitters -produced by neurons
-travel short distances across synapses
-allow system to react quickly
Endocrine system
- Uses chemicals to carry messages
-hormones secrete directly into the blood stream
-travel long distances to reach targets
-body reacts more slowly to change
Describe the structures and functions of the brain stem
Automatic function of the brain
Midbrain
Pons
Medulla
Describe the connective tissue layers that surround the brain and spinal cord
Meninges are made of
Dura mater
Subdural space
Arachnoid
Subarachnoid space
Pia mater
Not connective tissue but also surrounding the brain
Gray matter
White matter
Cerebrospinal fluid
Called CSF
cushions
between the layers of the meniges and the canals and cavities of brain and spinal column
May play a role of autonomic functions such as respiration and vomiting
List the cranial nerves and describe their functions
I - olfactory
II - optic
III - Oculomotor -
IV- trochlear -
V- trigeminal -
VI- abducent
VII- Facial
VIII vestibulocochlear
VIIII- Glossopharyngeal -
X- Vagus
XI - Accessory
XII Hypoglossal
(dorsal sensory, ventral motor)
Oh, ongoing orgasmic torrential triumphant arousal forcing vocal gloating violently spasmodic high
Six sailors made merry but my butthole said big bounces make messes
Differentiate between sympathetic and parasympathetic divisions of the autonomic nervous system
Sympathetic - flight or fight
Parasympathetic - rest or restore (or rest and digest)
Describe the components of reflex arc
Receptors→sensory neuron→spinal cord→motor neuron→muscles.
List reflexes
Stretch reflex
Withdrawal reflex
Crossed extensor reflex
palpebral reflex
pupillary light reflex
stretch reflex
Simple monosynaptic or two neuron reflex arc
When your patellar ligament is tapped
withdrawal reflex
Also called flexor reflex
moving limb away from hot stove
crossed extensor reflex
Afferent sensory impulse crosses to the other side of the spinal cord and stimulates muscles that extend the opposite limb
Stepping on a sharp tack
papebral reflex
light tap on medial canthus produces blink
less important
receptors on eyelid margins -
travels via sensory neurons in CN V to the pons
Synapses with neurons in pons
Travels via CN VII to muscles that blink
pupillary light reflex
A normal response to shining the light in the eye of animal is for both eyes to constrict.
Nervous system overview
Electronic communication system within body
Control and integrates all body activities within the limits of life
3 basic functions
- Stimulus
— sensory receptors
-Processing - interpreting and remembering
-Response
– reacting to changes with effectors
—- motor functions
—- glandular functions
Organization of the nervous system
CNS
-brain
-spinal cord
PNS
-spinal nerves
-cranial
autonomic system
-Parasympathetic
-sympathetic
Mixed nerves
Contain both efferent and afferent nerves
Most nerves in PNS are mixed nerves
Nervous system response pathway
*Sensory division
- somatic and visceral nerve fibers conduct afferent impulses
*PNS-Cranial and spinal nerves (communication line between
CNS/Spine and rest of body)
*CNS
-Brain and spinal cord- integrate and control what’s happening
*PNS passes efferent signals to
*Motor Division - conducts efferent impulses from CNS to effectors
*Autonomic or Somatic System
Neurons
Basic functional unit of the nervous system
Have a high requirement for oxygen
Cannot reproduce but can regenerate cell processes
Have support and protection from neuroglia cells
neuroglia cells
Helper nerve cells
Smaller and more numerous
neuron cell body
Soma
or perikaryon
Processes information
Axons
Also called nerve fibers
Efferent - conducts nerve impulses away
Single, long process
May be covered with myelin sheath
Dendrites
Afferent - Bring the nerve impulse to the cell body (receive)
Short, numerous and multibranched
May serve as sensory receptor
Myelin sheath
Cell membrane of glial cells tightly wrapped around an axon
-two most common
– oligodendrocytes- CNS
– Schwann cells -in nerves outside the CNS
Nerve fibers
Nerve fibers are bundles of axons
Mylen Sheath Neves
Conduct messages faster than non-myelinated
Myelinated axons
multiple oligodendrocytes (CNS) or schwann cells (PNS) cover entire length of axon
Nodes of Ranvier - the gaps between the adjacent glial cells
- increased rate of transmission
Neuron Function Overview
Sodium Potassium Pump (up the down elevator)
-Specialized molecule to maintain resting potential
-Pumps Sodium to the outside of the cell
-Pumps potassium inside the cell
Resting membrane potential
-difference in electrical charge across the membrane
- net negative charge
Nerve Impulse
Resting membrane potential
Depolarization - sodium rushes in cell
Repolarization- Potassium rushes out to rebalance
Refractory (Resting) period- requires lots of ATP
Threshhold stimulus
Sufficient stimulus to make neuron respond and cause a wave of depolarization (nerve impulse)
- All or nothing principle- neuron depolarizes to it’s maximum strength or not at all
-Conduction of action potential
-spreading of wave
-open sodium channels in sufficient numbers to allow depolarlization
Depolarization
Neuron receives external stimulus
Na channel opens on neuron cell membrane
Na ions flow into cell by passive diffusion
- charge now positive in cell
- switching of negative to positive is an action potential
Repolarization
Na channel closes
K+ channel opens
K+ diffuses out of cell
Net charge is returning to negative
Refractory Period
Repolarization ends
Na-K+ pump moves Na outside and K+ ions in, back to it’s original sides
Lots of ATP need
Resting state restored
Neuron insensitive to additional stimuli
Absolute refractory period
- during Na influx and early potassium outflow
Relative refractory period during the end of the repolarization period
- may be possible to stimulate another depolarization if stimulus is very large
Saltatory
Moves along myelinated nerve fibers
faster
Synapse
the junction between two neurons or a neuron and a target cell
synaptic cleft
the gap between two adjacent neurons
presynaptic neuron
releases neurotrasnmitter
brings depolarization to synapse
presynaptic neuron
releases neurotrasnmitter
brings depolarization to synapse
postsynaptic neuron
contains receptors for neuortransmitter
Synaptic transmission
Perpetuation of the nerve impulse from one nerve to the next
-axon
-telodendrion
- terminal bouton (synaptic bulb or knob)
-vesicles
Depolarization wave causes vesicles to dump neurotransmitters into cleft
Need to find the correct, specific receptors
Telodendrion
The branched end of an axon , each branch terminates in a neurotransmitter-filled synaptic end bulb
catecholamines
norepinephrine
dopamine
epinephrine
Recycling Neurotransmitters
Body’s way of stopping the effects of neurotransmitters
acetylcholinesterase
-enzyme found on postsynaptic transmitter
-breaks down acetylcholine
monoamine oxidase (MAO)
-breaks down norepinephrine
Types of nerves
Sensory
Motor
Mixed - all spinal nerves
Note- nerves are bundles of neurons
Types of neurons
Sensory neurons
Motor neurons
interneurons
Nerve tracts
Bundles of axons in CNS
-either sensory, motor, or mixeda
brainstem
many cranial nerves originate here
basic support functions of life
medulla oblongata
pons
midbrain
meninges
connective tissue layers that surround the brain and spinal cord
supplies nutrients, oxygen and cushioning
dura mater - thick, fibrous for protection
arachnoid -delicate, spiderweb like - connective tissue
pia mater - surface of brain, very thin “hugs the gray matter”
Blood-brain barrier
Functional barrier separating the capillaries of the brain from the nervous tissue itself.
Made of astrocytes (neuroglia)
Spinal cord
Caudal continuation of brain stem outside the skull
Dorsal nerve roots
Ventral nerve roots
Dorsal horns
Central horns
central canal - filled with CSF
composed of gray matter on inside
white matter on outside
Cranial nerves
12 pairs of nerves in PNS originate from brain
10 of the 12 nerves attached to the brain stem
-
Spinal Nerves
36 pairs in dogs
Spinal nerve pathway
reflex
Stimulous response that bipasses the brain
4 types -
somatic
automatic
contralateral
Olfactory nerve
Sensory smell
mnemonic -
Oh - olfactory
Six - sensory
Optic nerve
sensory vision
mnemonic -
Orgasmic -Optic
Sailors - sense
oh, ongoing orgasmic torrential triumphant arousal forcing (a) vocal gloating violently spasmodic high
Six sailors made merry but my butthole said big bounces make messes
mnemonic
Oh, ongoing orgasmic torrential triumphant arousal forcing (a) vocal gloating violently spasmodic high
Six sailors made merry but my butthole said big bounces make messes
Oculomotor -
motor (eye movement, pupil size, focusing)
mnemonic
Orgasmic - oculomotor
Made- motor
Oh, ongoing orgasmic torrential triumphant arousal forcing (a) vocal gloating violently spasmodic high
Six sailors made merry but my butthole said big bounces make messes
-Trochlear
motor (eye movement)
mnemonic
Torrential - trochlear
Merry- motor
Oh, ongoing orgasmic torrential triumphant arousal forcing (a) vocal gloating violently spasmodic high
Six sailors made merry but my butthole said big bounces make messes
Trigeminal
sensory (head and teeth/chewing)
mnemonic
triumph- trigeminal
but -both
Oh, ongoing orgasmic torrential triumphant arousal forcing (a) vocal gloating violently spasmodic high
Six sailors made merry but my butthole said big bounces make messes
Abducent
motor eye movement
mnemonic
arousal -abducent
my- motor
Oh, ongoing orgasmic torrential triumphant arousal forcing (a) vocal gloating violently spasmodic high
Six sailors made merry but my butthole said big bounces make messes
Facial
Both (face and scalp movement, salivation, tears, taste)
mnemonic
Forcing- facial
Butthole- both
Oh, ongoing orgasmic torrential triumphant arousal forcing (a) vocal gloating violently spasmodic high
Six sailors made merry but my butthole said big bounces make messes
Vestibulocochlear
Sensory- balance, hearing
mnemonic
Violent- vestibulocochlear
Said- sensory
Oh, ongoing orgasmic torrential triumphant arousal forcing (a) vocal gloating violently spasmodic high
Six sailors made merry but my butthole said big bounces make messes
Glossopharyngeal
both (tongue movement, swallowing
mnemonic
Gloating- glossopharyngeal
Big- both
Oh, ongoing orgasmic torrential triumphant arousal, forcing a vocal gloating violent spasmodic high
Six sailors made merry but my butthole said big bounces make messes
Vagus
Both- sensory from GI tract and reparatory tree, motor throat area and motor abdominal thoracic regions
mnemonic
Violent- vagus
Bounces- both
Oh, ongoing orgasmic torrential triumphant arousal, forcing vocal gloating violent spasmodic high
Six sailors made merry but my butthole said big bounces make messes
Spinal Accessory
Motor -head
Mnemonic
Spasmodic- Spinal accessory
Make - motor
Oh, ongoing orgasmic torrential triumphant arousal, forcing vocal gloating violent spasmodic high
Six sailor made merry but my butthole said big bounces make messes
Hypoglossol
Motor- tongue
Mnemonic
High0 Hypoglossol
Oh, ongoing orgasmic torrential triumphant arousal, forcing vocal gloating, violent, spasmodic high
Six sailors made merry but my butthole said big bounces make messes
Contralateral reflexes
Start on one side of the body and cross to the other
Example, step on a nail and the leg not on the nail braces
Ipsilateral
Same side of the body
Autonomic System
Made up of 2 motor neurons from spinal cord
-controls all involuntary internal structures
-regulated by the hypothalamus
-Controls autonomic functions at both divisions- Parasympathetic and sympathetic
Anatomy
- Pre-ganglion neuron
- ganglion neuron and pre-ganglion synapse,
-Post ganglion
-post ganglion synapse on target organ
Sympathetic Division
Nerves emerge from the the thoraco-lumbar system
flight or fight
effects-
-increased heart rate
-bronchioles dilate
-decreased production salivary glands
-dilated pupils
-sweat glands- secretion increased
-GI motility - decreased
target organ receptors
- blood vessels in skin, GI tract, skeletal muscles
–contain adrenergic receptors
Parasympathetic Division
Nerves emerge from brain and sacral system -cranial-sacral
Normal homeostasis - normally in charge
cranial/sacral region
long preganglion neuron
Both synapses contain acetylcholine
nicotinic receptors (like sympathetic)
muscarinic receptors
Ganglion
An accumulation of nerve cell bodies outside the CNS
Norepinephrine neurotransmitter
Sympathetic division
Released by adrenergic neurons and adrenal medulla
adrenergic
catecholamine
Sympathetic and parasympathetic pathway
preganglion synapse (myelinated)
-nicotinic receptors acetylcholine
Postganglion synapse (unmyelinated)
-adrenergic receptors
