Chapter 2

Front 1

dendrites

Back 1

o Feathery extensions that branch from the neuron into the immediate neighborhood of the cell body

Front 2

axon

Back 2

o The part of the neuron that extends from the cell body functions similarly in all creatures.

• Its main function is to transmit electrochemical info from the cell body to the synapse through microtubules along its length

Front 3

terminal buttons
(AKA axon terminals)

Back 3

o Site of interneuronal contact where neurochemical information transmits from one neuron to another

o This chemical in turn affects another neuron or muscle in either an excitatory or an inhibitory manner

o Signals that travel along the axon are electrical & the transfer of neurotransmitters across synapses from one neuron to another, is chemical

o Researchers can therefore study & analyze the brain through electrical means (EEG)

Front 4

• 3 principal classifications of neurons defined by # of axons

Back 4

o multipolar (2 or more axons)
o bipolar (2 axons)
o monopolar/unipolar neurons (1 axon)

Front 5

• Motor neurons

Back 5

o make muscles contract & change activity of glands

Front 6

interneurons

Back 6

• short axons or no axons
b/c they integrate neural activity w/in a specific brain region.

Front 7

• sensory neurons

Back 7

respond directly to changes in light, touch temperature odor (etc.)
o most neurons are interneurons b/c they receive input & send output

Front 8

3 major types of white matter fibers

Back 8

• intracerebral(association) fibers:
o connect regions w/in 1 hemisphere
• intercerebral (commissural) fibers:
o connect structures in 2 hemispheres
• projection fibers
o connect subcortical structures to the cortex & vice versa

Front 9

Nuclei

Back 9

clusters of gray cell bodies in the Central Nervous System

Front 10

Ganglia

Back 10

Gray cell bodies in the peripheral nervous system.

Front 11

Neuroglia

Back 11

• Supporting cells of the nervous system
• Play an important role in supplying nutrients and oxygen to neurons
• More numerous than nerve cells, support cells make up more than half of the volume of the nervous system. Helps neurons in various ways
• Not directly involved in transmitting nerve impulses

Front 12

• Glia cells

Back 12

AKA“nerve glue”
maintain the functioning of neurons by physically & chemically buffering them from each other.
• Insulate neurons from each other so messages don’t get mixed
• Control oxygen supply & chemicals & act as housekeepers, metabolizing & removing carcasses of neurons destroyed by injury or disease

Front 13

• Astrocytes

Back 13

o Highly branched cells that occupy much space btw neurons in gray matter

Front 14

when do neurons show resting potential or membrane potential? (inactivity)

Back 14

slight electrical imbalance between the inner & outer surfaces of the membrane caused by separation of electrically charged ions

Front 15

4 important ions

Back 15

1) Sodium Na+
2) Potassium K+
3) Calcium Ca++
4) Chloride Cl-

Front 16

When a neuron is not firing the membrane is ______.

Where are the sodium ions?

Back 16

The membrane is at rest.

Sodium ions are trapped outside.

Front 17

An imbalance in electrical charge maintains what?

Back 17

The tension in the cell. This means that it is ready to fire rapidly in response to a stimuli

Front 18

Sodium-potassium pump

Back 18

o Many individual protein molecules in membrane pump sodium out of the axon
o Active transport system exchanges 3 sodium ions for every 2 Potassium ions that push in
o Pump actively moves potassium into the neuron, spending energy in the process

Front 19

Action Potential

Back 19

• To generate nerve impulse, cell membrane must first depolarize
• Depolarization begins when a sodium channel across membrane briefly opens and sodium ions pass through it into the cell, reducing voltage
• Nerve impulse spreads down the axon, as voltage-controlled sodium ion channels open sequentially like falling dominoes

Front 20

• Structure of Synapses

Back 20

o Terminal buttons harbor oval structures called synaptic vesicles, which has neurotransmitters
o These vesicles are unique cellular structures that typically cluster close to the presynaptic membrane
o Neurotransmitters are synthesized until they’re delivered to receptor sites
o There are numerous neurotransmitter molecules, each kind is shaped differently and w/ its own fit to a specific receptor

Front 21

Synaptic Transmission

Back 21

• Excitatory postsynaptic potential (EPSP) increases the probability that the postsynaptic cell will reach its threshold
• Thus greater depolarization than normal is required to reach action potential, which becomes less probable
• This is an inhibitory postsynaptic potential (IPSP)

Front 22

Neurotransmitters

Back 22

• Neurotransmitters permit exchange of information among neurons & between neurons & other cells
• Neurotransmitter types are classified according to molecular size
• Just as each neurotransmitter has a specific shape, comparable to a key, each receptor site also has a specific structure analogous to a lock
• Thus, a specific neurotransmitter will attach itself only to a receptor with an appropriate fit

Front 23

Acetylchonline
(AKA Ach or choline)

Back 23

o 1st neurotransmitter to be identified in the early 1900s; discovered to stimulate parasympathetic nervous system
o stimulates muscle contraction
o in central nervous system & brain, acetylcholine affects wide behavioral repertoire
o one of its most important functions may be alertness, attention, & memory

Front 24

Serotonin

Back 24

o System originates in small area of the brainstem called nuclei of the raphe
o Low levels are also associated w/ depression
o Excess of serotonin related to schizophrenia

Front 25

Norepinephrine

Back 25

o Norepinephrine forms predominantly among neurons & their nuclei in brainstem site named the locus ceruleus (“blue place”)
o Researchers think norepinephrine is important in regulating mood, memory, hormones (via the hypothalamus cerebral blood flow, & motor behavior

Front 26

Dopamine

Back 26

o The majority of dopa minergic neurons dopamine in the substantia nigra
o Dopamine pathway to the frontal cortex has been implicated in schizophrenia
o Dopamine hypothesis: suggests schizophrenia arises from overactivity of dopaminergic synapses
o Researchers think second pathway to basal ganglia is responsible for tardive dyskinisia → movement disorder
• Tardive dyskinisia is a side effect of antipsychotic medications
o Basal ganglia plays important role in organizing motor behavior and thus think dopamine is crucial to movement
o Too little dopamine is found in Parkinson’s
o Too much dopamine is found in schizophrenia

Front 27

Amino Acids

Back 27

The building blocks of protein. They are present in all body cells.

Front 28

How many pairs of spinal nerves make up the Somatic Nervous System?

Back 28

31 pairs

Front 29

Regeneration of Neurons

Back 29

• The capacity for regeneration in Peripheral Nervous System is actually quite good
• Humans are born w/ as many neurons as they will ever have
• The central nervous system has little of the spontaneous cellular regeneration require to reconnect damaged axon to is normal target
• One major finding by neurophysiologists has been that an active training rehabilitation program facilitates recovery of function
• It’s within this area of assessment & intervention that clinical neurophysiologists have made some of their greatest advancements

Front 30

synapse

Back 30

the place where electrical nerve impulses cause the release of a neurotransmitter