ch 12 Flashcards by Abby Davis

what is neurobiology (neurology)

combines the behavioral and life sciences

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what is the nervous system the foundation of

the concious experience, personality, and and life sciences

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what is the difference between endocrine and nervous system

Endocrine system: communicates by means of chemical messengers (hormones) secreted into to the blood
wireless
quickest is 2 seconds
long lasting

Nervous system: employs electrical and chemical means to send messages from cell to cell
slowest is 2 secs
short term

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what are the three basic steps the nervous system carries out

sense organs receive information about changes in body/enviro and transmit coded messages to brain and spinal cord (CNS)

CNS processes the inf relates it to past eperienes and determines the appropriate response

CNS issues comman to muscle and gland cells to carry out response

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what are the two major subdivisions of the nervous system

central nervous system

brain and spinal cord enclosed by cranium and vertebral column
processing region

peripheral nervous system
- all nervous system expcept brain and spinal cord
composed of nerves and ganglia

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what is a nerve and ganglion

nerve: bundle of nerve fibers (axons) wrapped in fibrous connective tissue
- named for the bones they run next to

ganglion:a knot-like swelling in a nerve where neuron cell bodies (organelles) are concentrated

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what is the peripheral nervous system

contains sensory and motor divisions each with somatic and visceral subdivisions

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what is the sensory (afferent) division

carries signals from receptors to CNS

Somatic sensory division: carries signals from receptors in the skin, muscles, bones, and joints

Visceral sensory division: carries signals from the viscera (heart, lungs, stomach, and urinary bladder)

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what is the motor efferent division

carries signals from CNS to effectors (glands and muscles that carry out the body’s response)

Somatic motor division:

carries signals to skeletal muscles
Output produces muscular contraction as well as somatic reflexes—involuntary muscle contractions

Visceral motor division (autonomic nervous system):-
carries signals to glands, cardiac and smooth muscle
-Its involuntary responses are visceral reflexes

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what are the two subdivisions of the visceral motor division

Sympathetic division

Tends to arouse body for action
Accelerating heart beat and respiration, while inhibiting digestive and urinary systems
fight or flight

Parasympathetic division

Tends to have calming effect
Slows heart rate and breathing
Stimulates digestive and urinary systems
rest/digest

80-90% one 10-20% the other

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what is the quickest way between the two

adrenaline
only way to quickly go between the 2

it is 2 seconds

both nevous and endocrine

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what are the functions of neurons

excitability (irritability)- changes in enviro changes (stimuli)

conductivity
-response to stimluli - electrical signals that are quickly conducted to other cells distant locations

secretion
-when signal reaches end of nerve fiber, the cell secretes a chemical neurotransmitter influences next cell

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what are the fuctional classes of neurons

sensory neurons (afferent)

interneurons

motor neuron (efferent)

anatomical name is in parathensis

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sensory afferent neurons

Detect stimuli and transmit information about them toward the CNS

(hearing, sight, smelll, taste, touch, pain)

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interneurons

Lie entirely within CNS connecting motor and sensory pathways (about 90% of all neurons)

Receive signals from many neurons and carry out integrative functions (make decisions on responses)

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motor efferent neurons

Send signals out to muscles and gland cells (the effectors)

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neurosoma (soma or cell body)

1 of the 3 structures of a neuron

control center of neuron

Has a single, centrally located nucleus with large nucleolus

Cytoplasm contains mitochondria, lysosomes, Golgi complex, inclusions, extensive rough ER and cytoskeleton

no centrioles and no mitosis

lots rough ER, golgi, mitochondria, nissl bodies

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what are nissl bodies

aggregations of cytoskeleton ROugh ER and golgi

Cytoskeleton has dense mesh of microtubules and neurofibrils (bundles of actin filaments) that compartmentalizes rough ER into dark-staining chromatophilic substance

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what are the three structures of a neuron

neurosoma

dendrites

axon

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what are dendrites

small extensions off soma (not extracellular)
lots of these

Primary site for receiving signals from other neurons

The more dendrites the neuron has, the more information it can receive

Provide precise pathways for the reception and processing of information

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what is an axon (nerve fiber)

long extensions of soma, cytoplasm contain this ( 1 of these per soma)

originates from a mound on the neurosoma called the axon hillock

Axon is cylindrical, relatively unbranched for most of its length

Branch extensively on distal end

Specialized for rapid conduction of signals to distant points

may be enclosed by myelin

what is axoplasm

and axolemma

axoplasm: cytoplasm of axon

Axolemma: plasma membrane of axon

what are terminal arborization

found on the distal end of the axon

extensive complex of fine branches

what is axon terminal

little swelling that forms a junction (synapse) with the next cell

Contains synaptic vesicles full of neurotransmitter

what are the structural classifications of neurons

mulipolar bipolar unipolar anaxonic

what is multipolar neuron

One axon and multiple dendrites Most common – most neurons in CNS

bipolar neuron

One axon and one dendrite Olfactory cells, retina, inner ear really long soma =middle

unipolar neuron

Single process leading away from neurosoma Sensory cells from skin and organs to spinal cord fast dendrite/axon connected, soma is off to side QUICKEST spinal cord/pain senstation

anaxonic neuron

Many dendrites but no axon Retina, brain, and adrenal gland no electrical signal just process

what are supportive cells (Neuroglia)

way more of them then neurons (outnumber 10:1 = 90%:10%) protect neurons/help function bind neurons together =framework for nervous tissue in fetus guide neruons to their destination 90% cns mass isolates heat to make sure they dont impede other neurons isolates electrical signal from H2O

what are the different types of neuroglia in The CNS

oligodendrocytes ependymal cells microglia astrocytes

oligodendrocytes

Form myelin sheaths in CNS that speed signal conduction Arm-like processes wrap around nerve fibers make myelin

what is myelin

insulator for electrical signals located around axon

ependymal cells

Line internal cavities of the brain; secrete and circulate cerebrospinal fluid (CSF) Cuboidal epithelium with cilia on apical surface isolate H2O = CSF

microglia

Wander through CNS looking for debris and damage Develop from white blood cells (monocytes) and become concentrated in areas of damage show up during fetal development got stuck there now break down stuff lots of lysosomes

atrocytes

Most abundant glial cell in CNS, covering brain surface and most nonsynaptic regions of neurons in the gray matter supportive framework have perivascular feet that contract blood capillaries and stimulate them to seal = blood brain barrier monitor neuron act regulate blood flow

what are the different neuroglia of the PNS

schwann cells | satelite cells

schwann cells

Envelope nerve fibers in PNS Wind repeatedly around a nerve fiber Produce a myelin sheath similar to the ones produced by oligodendrocytes in CNS Assist in regeneration of damaged fibers

satelite cells

Surround the neurosomas in ganglia of the PNS Provide electrical insulation around the neurosoma Regulate the chemical environment of the neurons

myelin

contains mylein sheath and myelination

myelin sheath

nsulation around a nerve fiber Formed by oligodendrocytes in CNS and Schwann cells in PNS Consists of the plasma membrane of glial cells 20% protein and 80% lipid multplie scholorsis = disease of decrease myelin

myelination

production of the myelin sheath Begins at week 14 of fetal development Proceeds rapidly during infancy Completed in late adolescence Dietary fat is important to CNS development

schwann cells of the PNS

sprial repeadtedly around a single nerve fiber lays down hundred layers of membrane no cytoplasm between membrane

neurilemma

: thick, outermost coil of myelin sheath Contains nucleus and most of its cytoplasm External to neurilemma is basal lamina and a thin layer of fibrous connective tissue—endoneurium

what are the segments of myelin

nodes of ranvier internodes initail segment trigger zone

nodes of ranvier

gap between segments | bare wire

internoteds

myelin-covered segments from one gap to the next

intial segment

short section of nerve fiber between the axon hillock and the first glial cell

trigger zone

the axon hillock and the initial segment Play an important role in initiating a nerve signal

what are the two factors that control the speed at which nerve signal travels along surface of nerve fiber

diameter of fiber presence of myelin fastest: myelin presnt and large slowest: no myelin and small