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Nervous System Alissa Tagle Period 3 - Coggle Diagram
Nervous System
Alissa Tagle
Period 3
Major divisions and subdivisions of the nervous system
Central Nervous System
made up of brain and spinal cord
responsible for
integration
of
information
Peripheral Nervous System
somatic nervous system
connects CNS to skeletal mucles, concious activites
autonomic nervous sytem
Connects nervous system to viscera & controls subconscious activities
Sympathetic division
Parasympathetic division
consists of cranial and spinal nerves that connect CNS to body parts
Classification of neurons
Structural classifications
differ in shape, size, and structure
multipolar neurons
has may dendrites, one axon from cell body
-most neurons are multipolar
bipolar neurons
has 2 processes extending from cell body: dendrite and axon
-found in eyes nose and ears
unipolar neurons
only one process extending from cell body
Functional Classifications
Interneuron (association or internuncial neurons)
multipolar neurons
lie within CNS and form links between other neurons
Motoer (efferent) neurons
multipolar neurons
conducts impulses from CNS to peripheral effectors
Sensory(afferent) neurons
Conducts impulses from periphial receptors to CNS
neurons usually unipolar, some bipolar
Reflex arc (major parts & functions)
Sensory Neuron: carries info from receptor toward CNS
Interneuron(in brain/spinal cord): carries info from sensory neuron
Receptor: detects change
Motor Neuron: carries command to effector
Effector(muscle/gland): carries out reflex response
Spinal nerves (31)
Main branches of spinal nerves form plexuses
(EXCEPT THORACIC)
Brachial Plexuses(C5-T1):
-lower cervical and upper thoracic nerves
-supply muscles/skin of arms forearms ans hands
Lumbosacaral Plexuses(L1-S4):
-lower spinal cord
-supply muscle/skin of lower abdomen, external genitalia, buttocks, & legs
Cervical Plexuses(C1-C4):
-either side of neck
-supply muscles and skin of neck; also phrenic nerves (control diaphragm)
-8 pairs of cervical nerves
-12 pairs of thoracic nerves
-5 pairs of lumbar nerves
-1 pair of coccygeal nerves
all except the first pair are mixed nerves
Each arise from 2 roots: dorsal and ventral roots
31 pairs of spinal nerves
Tissues (structure & function of neurons and neuroglia)
Neurons
structure: cell body(soma), dendrites, axon
1 axon per each neuron
myelin sheath
of axons creates
Nodes of Ranive
r(gaps between); faster conduction
Neuroglia
*are nerve glue; they support neurons
2 types of neuroglia cells in PNS
Schwann cells
myelin producing cells of PNS
Satellite cells
provide protective covering around cell bodies
4 types of neuroglia cells in CNS
Oligodendrocytes
forms the myelin sheath around axons in brain and spinal cord
Ependymal cells
produces cerebrospinal fluid in CNS
Astrocytes
functions:
-gives structural support,
-forms blood brain barrier, which protects brain tissue
(lies between blood vessels and neurons)
Microglia
cells that function as phagocytes for bacterial cells & cellular debris, produce scar tissue
functions: fill spaces, structure support, protect, and insulate neurons
Drugs of abuse (Mouse Party)
Ecstasy
Neurotransmitter affected: Serotonin
Causes altered mood, sleepiness, perception, and appetite; stimulates mild release of dopamine along reward pathway
Marijuana
Neurotransmitter affected: dopamine
causes a slow down in persons movement and makes them feel calm and relaxed
Heroine
Neurotransmitter affected: Dopamine
causes feeling of sedation and well being
Methamphetamine
Neurotransmitter affected: Dopamine
causes feelings of pleasure and exhilieration because of reward pathway; highly addictive
Alcohol
Neurotransmitter affected: GABA and Glutamate
causes persons memory formation and decision making and impulse control to be altered
Cocaine
Neurotransmitter affected: Dopamine
causes reward pathways to be activated and will make users fidgety
LSD
Causes feeling of wakefulness and evokes a startle response
Neurotransmitter affected: Serotonin
Major parts and functions of the brain
Diencephalon
main parts
: Thalamus and hypothalamus
Thalamous
functions:: sorting and directing sensory info; awareness: pain touch, temp
channels all sensory inpulses,
except smell
Hypothalamous
functions: maintain homeostasis;, regulates visceral activities; links endocrine system
regulates:
-heart rate and blood presse
-body temp and water electorlyte balance
-hunger and body weight
-stimulates posterior gland to secrete hormones
processes sensory input & controls homeostatic processes
lies between cerebral hemispheres & above midbrain
Limbic system
controls emotional experience & expression
modifies behavior; pleasant or unpleasant
Cerebellum
cerebellum is two hemisphere connected by vermis
functions: integrate sensory info about the
position
of
body parts
Cerebrum
Largest portion of the brain
associated with higher level thinking
contains corpus callosum; connects 2 hemispheres
functions: interpretation of sensory input, memory, intelligence, personality, reasoning, initiates voluntary muscle movements
Cerebral cortex
Visual area: posterior occipital lobe
Auditory area: posterior temporal
Cutaneous senses: anterior parietal lobe
Taste area: base of central sulcus & insula
*divided into: sensory, association, and motor areas
*They interpret sensory input/produces feeling/sensation
Smell area: deep in temporal lobe
Association areas
- analyze/interpret sensory impulse, function in reasoning, judgement, emotion, verbalizing ideas, storing memory
Occipital lobe
analyze visual
Next to sensory areas
analyze sensory input
Parietal lobe
understands speech/choosing words
General interpretive area
found at junctions of parietal, temporal
Wernick's area-understands language
Brocas motor area- controls muscles to speak
Frontal lobe
higher level processes(planning, problemsolving)
Brainstem
made up of:
midbrain
,
pons
, and
medulla oblongata
Midbrain
between diecephalon and pons
contains main motor pathways between cerebrum and lower portions of nervous sys
Medulla Oblongata
houses nuclei that control visceral functions
cardiac center
alters heart rate
vasomotor center
controls vasoconstriction/vasodiilation of blood vessels
respiratory center
controls rate and depth of breathing
*also controls coughing sneezing, swallowing, vomiting
*transmits all ascending and descending impulses between brain and spinal cord
Pons
contains centers that help regulate the rate and depth of breathing
Disorders/Diseases
Alzhimers Disease
a form of dementia associated with age
Spinal Cord Injury
damage to spinal cord
Autism
brain disorder that makes it difficult to communicate
Meningitis
inflammation of meninges surrounding brain
Cerebrovascular Accident (stroke)
Occurs when blood flow to a portion of the brain is halted
Multiple Sclerosis
autoimmune disease that damages the myelin sheath
Autonomic nervous system
Sympathetic division
active in stress (fight or flight)
has short preganglionic fibers from grey matter in thoracic and lumbar regions
axons exit spinal cord via ventral roots of spinal nerves
Parasympathetic division
active when normal (rest and digest)
long preganglionic fibers that arise from brainstem & saceral region of spine
preganglionic fibers extend out in cranial/saceral nerves and synapses
controls visceral motor functions of smooth muscle, cardiac muscle, & glands
keeps homeostasis
regulated by reflexes that have sensory receptors in viscera
Neurotransmitters
preganglionic
fibers of
parasympathetic
and
sympathetic
divisions all release
ACh
(called
Cholinergic fibers
)
postganglionic
fibers of
parasympathetic
division also releases
ACh
(cholinegic)
postganglionic
fibers of
sympathetic
division release
norepinrphrin
(noradrenalin); called
adrenic fiber
Action potential & the Nerve Impulse
1)
Resting membrane potential
(-70mV)
a. greater concentration of sodium outside cell
b. greater concentration of potassium inside cell
1a) stimulus opens sodium (Na) channels; causes potential to change from -70 to-55 mV
2)
Threshold Stimulus
(-55mV)
2a) upon reaching threshold potential, voltage gated sodium channels open and change charge to +30mV
3)
Depolarization
(30mV)
a. depolarization is when the charge inside and outside the neuron goes from - to +
3a) once action potential is released, cell responds by returning to resting potential (-70mV)
4)
Repolarization
a. potassium ions flood out cell
4a) @ the end of repolarization, a slight over shoot occurs (hyperpolarization)
5)
Hyperpolarization
(dips below -70mV)
5a) sodium and potassium pumps move spdium inos out of cell and potassium into cell
action potential occurs at -55mV
Neurons and muscle cells are excitable
refractory period- period during and after an action potential (the break)
Cell membranes are neurons are polarized (charge inside is more negative than outside)
Types of impulse conduction
continuous conduction (unmyelinated)
saltatory conduction (myelinated axons); which are faster
Neurotransmitters
Norepinephrine(PNS)
may excite some autonomic nervous system actions
Dopamine(CNS)
creates sense of feeling good;
deficiency
associated with
Parkinson Disease
Norepinephrine(CNS)
creates sense of feeling good; low levels=depression
Dopamine(PNS)
limited in actions in autonomic nervous system; may excite of inhibit
Seritonin(CNS)
Primary inhibitory;leads to sleepiness;
LSD blocks action
Histamine(CNS)
release in hypothalamus promotes altertness
Acetycholine(PNS)
stimulates skeletal muscle @ neuromuscular junction; may inhibit autonomic actions
Acetycholine(CNS)
controls skeletal muscle
Connective Tissue Coverings
Arachnoid matter
middle layer
Pia matter
inner most layer
Dura matter
outer most layer; tough dense CT,
Epineurium
Outer
covering
of a
nerve
Endoneurium
covering
around
individual nerve fibers
(axon)
Perineurium
covering
around
fascicle
(bundle of nerve fibers)
subarachnoid space
between arachnoid and pia; contains cerebrospinal fluid
Major functions of the nervous system
Integrative function
coordinate sensory info with PNS
processing info is basis for
decision making
Motor function
nerve impulses from CNS are conducted along motor neurons to
effectors
(muscle/glands that respond to CNS)
Sensory function
provided by sensory receptors that detect internal/external change
1) info travels from receptors to sensory neurons
2) then transports into CNS
thinking, movement, internal process of physiology
Cranial nerves (12)
6) Abducens (primarily motor)- move eyes
7) Facial (mixed)-
sensory
; taste
motor
; facial expressions, tear gland, salivary glands
8) Vestibulocochlear (sensory)
a) Vestibular branch- sensory associated with equilibrium
b) Cochlear branch- sensory associated with hearing
5) Trigeminial (mixed)
b) Maxillary division- impulses to upper teeth, upper gum, upper lip, & skin
c) Mandibular division- impulses to lower teeth, lower gum, lower lip, jaw
a) Ophthalmic division- impulses to surface of eyes, tear glands & scalp
4) Trochlear(primary motor) - movement of eyes
9) Glossopharyngeal (mixed)
sensory
; conductes impulses from pharynx, tonsils, posterior tongue, and carotid arteries
motor
; controls movement of pharynx used in swallowing and to salivary glands
3) Oculomotor (primairly motor) movement to raise eyelids and adjust light coming in
10) Vagus (mixed)
somatic motor
conducted impulses for muscles to do with speech and swallowing;
autonomic motor
conducts impulses to heart, smooth muscle, and glands in thorax and abdomen
sensory conducts from the pharynx, larynx, esophagus, and viscera of thorax and abdomen
2) Optic(sensory) -sense of vision
11) Accessory (primarly motor)
a) Cranial branch- movement of the soft palate, pharynx, and larynx
b) Spinal branch- movement of neck and back
1) Olfactory(sensory) -sense of smell
12) Hypoglossal (primarily motor)- movment of tongue