BIOL 430 Unit 4 Lecture Exam (Nervous System)

3 functions of nervous tissue

sensory, integration & motor function

2 divisions of nervous system

central nervous sytem & peripheral nervous system

central nervous system (function & anatomy)

brain & spinal cord
responsible for thoughts, memories, and emotions

peripheral nervous system
(function & anatomy)

cranial & spinal nerves, receptors, ganglia & plexi

3 parts to peripheral nervous system

somatic, autonomic & enteric nervous system

somatic nervous system

voluntary skeletal muscle movement
body & special senses

autonomic nervous system

involuntary smooth/cardiac muscle
visceral senses (blood pH, stomach pH, etc)

enteric nervous system

gastrointestinal tract sensory information
GI senses & movement

2 kinds of cells in nervous tissue

neurons & neuroglia

neurons

electrically excitable & cannot divide

3 structural classification of neurons

sensory, interneuron & motor neuron

sensory neuron

afferent pathway

interneuron

carries information within CNS

motor neuron

efferent pathway

3 functional classification of neurons

pseudounipolar, multipolar & bipolar

pseudounipolar

neuron with one extension from cell body
(tends to be sensory)

multipolar neuron

neuron with multiple extensions from cell body
(tends to be motor)

bipolar neuron

neuron with 2 extensions from cell body
special sense organ

3 parts to neuron

cell body, dendrites & axon

neuroglia that myelinates neuron in PNS

Schwann cell

neuroglia that myelinates neurons in CNS

Oligodendrocyte

grey matter made up of

neuronal cell bodies

white matter made up of

myelinated axons

multiple sclerosis

autoimmune disease
attack of myelin sheath
ultimately leads to decreased sensation

neuroglia characteristics

smaller & more numerous
not electrically excitable
can divide

-glioma

cancer of neuroglia

neuroglia functions

nourish & protect neurons

2 kinds of neuroglia in PNS

Schwann cells & satellite cells

Schwann cell

forms myelin sheath in PNS
aids axonal regrowth/repair

Satellite cell

supports sensory neurons in ganglia

4 kinds of neuroglia in CNS

oligodendrocyte, astrocyte, ependymal cell & microglia

oligodendrocyte

forms myelin sheath in CNS

astrocytes

forms blood brain barrier
takes up excess Na, K & neurotransmitters

ependymal cells

lines ventricular spaces
produce, monitor & circulate cerebrospinal fluid (CSF)

microglia

involved in immune response

resting membrane potential (RMP)

-70mV

3 factors of resting membrane potentials

unequal ion distribution
high K+ permeability (due to K+ leak channels)
Na+/K+ ATPase (pump)

intracellular charge

negative

extracellular charge

positive

Na+ Electrochemical potential

+60mV

K+ Electrochemical potential

-90 mV

graded potential

can summate
short distance communicate
involves ligand or mechanically gated ion channels

ligad gated Na+ channel

excitatory post synaptic potential (EPSP)

ligand gated K+/Cl- channel

inhibitory post synaptic potential (IPSP)

spatial summation

recruits increasing # of neurons

temporal summation

increased frequency of action potentials from single pre-synaptic neuron

action potentials

long distance communication
cannot be submated
involves voltage gated ion channels

threshold for action potential

-55 mV

4 phases of action potential

resting phase, depolarization, repolarization, hyperpolarization

Resting phase (gates)

v.gated Na+ activation gate- closed
v. gated Na+ inactivation gate- open
v. gated K+ gate- closed

depolarization (gates)

v. gated Na+ activation gate- open
v. gated Na+ inactivation gate- open
v. gated K+ gate- closed

repolarization (gates)

v. gated Na+ activation gate- open
v. gated Na+ inactivation gate- closed
v. gated K+ gate- open

hyper polarization (gates)

v. gated Na+ activation gate- closed
v. gated Na+ inactivation gate- open
v. gated K+ gate- open

refractory period

period of time when action potential cannot occur

2 kinds of refractory periods

absolute & relative

absolute refractory period

time during which another action potential cannot occur
v. gated Na+ activation gate open
v. gated K+ channel open & Na+ channels inactivating

relative refractory period

could potentially have another action potential but would require additional stimulus
v. gated K+ channels open & Na+ in resting state

tetrodotoxin (TTX)

paralytic neurotoxin
blocks v. gated Na+ channel

lidocaine/local anesthetics

blocks v. gated Na+ channel
prevents pain impulse from reaching brain

2 conduction types of action potentials

continuous & saltatory

continuous conduction

slow means of conduction
influx of Na+ depolarizes adjacent v. gated Na+ channel
domino effect

saltatory conduction

faster conduction
depolarizes adjacent Na+ channel @ node of Ranvier

3 Fiber types

A (large diameter & myelinated)
B (medium diameter & myelinated)
C (small diameter & unmyelinated)

electrical synapse

direct cell to cell communication
gap junctions
faster communication & synchronous

chemical synapse

chemical release between 2 cells/neurons

4 main categories of neurotransmitters (NT)

acetylcholine, amino acids, biogenic amines & adenosine

acetylcholine (as NT)

found at NMJ & main NT in SNS

amino acid NT

glutamate & GABA

glutamate

main excitatory a.a. NT

GABA (gamma-amino butyric acid)

main inhibitory a.a. NT
enhanced by depressants & anesthetics (valium, GHB, Rohypnol)

Biogenic amine NT

catecholamines (epinephrine, norepinephrine & dopamine)
serotonin

monoamine oxidase (MAO)

breaks down catecholamines

dopamine

associated w/pleasure & addiction
enhanced by sugar, cocaine, methamphetamine

serotonin

associated w/emotion, mood, sleep & appetite
enhanced by ecstasy (MDMA). SSRI

MAOI

monoamine oxidase inhibitor

SSRI

selective serotonin reuptake inhibitor

adenosine

inhibits RAS (reticular activating system)

RAS

reticular activating system
promotes wake-sleep cycle
caffeine enhances brain activity

neuronal regeneration in CNS

nonexistent

neuronal regeneration in PNS

possible if neurolemma (Schwann cell) present via regeneration tube

plasticity

ability to change based on experience
can make new synaptic contacts & dendrites

brain made up of

cerebrum, diencephalon, cerebellum & brain stem

3 brain coverings (superficial to deep)

dura mater
arachnoid mater
pia mater

headache causes

stretching of meninges (dehydration, vasodilation)

brain supplied by what blood vessels

carotid arteries & vertebral arteries

blood brain barrier

prevents substances from blood from getting to brain

to cross blood brain barrier

make substances lipophilic
shrink endothelial cells (hypertonic solution)

cerebrospinal fluid (CSF) functions

mechanical protection, chemical protection & circulation

CSF produced by what

choroid plexus

hydrocephalus

build up of CSF

cerebellum function

coordinate smooth movement, posture & balance

cerebellar damage

ataxia (loss of balance & posture)

diencephalon

contains thalamus, hypothalamus & pineal gland (epithalamus)

thalamus

major sensory relay station
transmits motor information from cerebellum/basal nuclei to cerebral cortex

hypothalamus

controls ANS
regulates eating, drinking, body temperature, circadian rhythm
produces hormones

epithalamus/pineal gland

produces melatonin

midbrain (mesencephalon)

visual & auditory reflex
subconscious movement

notable structures of midbrain

cerebral peduncles (white matter)
corpora quadrigemina (grey matter)
substation nigra (grey matter w/dopaminurgic neurons)

pons (metencephalon)

breathing control center

notable structures of pons

middle cerebellar peduncle (white matter)
pontine nuclei (grey matter)