1. Determine direction signals will spread 2. perform a selective action

Week 8 Ch 46 - Organization of the nervous system Flashcards by Danielle Nies

3 steps in nervous system work

Sensing
Processing
Effect

or
1. sensory
2. Integrative
3. motor

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Sensory receptor role

sense temp, chemicals, pain

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Processing info from sensory receptor and afferent nerve occurs in

Central nervous system

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Motor nervous system nerves are called

effectors

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Motor nervous system role (2)

Contracts muscles
Secretes chemical substances

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Integrative function of the nervous system

Processes information and gives appropriate response

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Synapse role (2)

Determine direction signals will spread
perform a selective action

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Memory for the nervous system is collected in

cerebral cortex (most)

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Nervous system memory function

compares new sensory experience with stored memories

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Major levels of CNS function (3)

Spinal cord level
Lower brain or subcortical level
Higher brain or coritical level

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Spinal cord level function

circuits good for things you don’t really have to think about

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Spinal cord level function examples

Walking, w/d from pain, support body against gravity, blood vessels, GI movement, urinary excretion

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Lower brain (subcortical) level funcion

Subconscious activites

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Lower brain (subcortical) level is mediated by

Medulla, Pons, midbrain, hypothalmus, cerebellus, basal ganglia

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Memory storehouse of the brain

Higher level cortical (specifically the hippocampus)

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Precision and thought process occur in

higher brain (cortical level)

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Higher brain (cortical) level functioning examples

learning a new skill, riding a bike, problem solving, open mind

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Two types of CNS synapses

Chemical
Electrical

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Chemical synapse location

CNS

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Presynapctic neuron secretes

neurotransmitter

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Post synaptic neuron role

neurotransmitter acts on receptor proteins, leading to excitation or inhibition

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How does the electrical synapse work?

Open fluid channels that conduct electricity

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Electrical synapses are dependent on

gap junctions

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Electical synapses are most common in_______ because_____

smooth muscle contractions because they help with coordination contractions and flow

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Chemical synapse direction

One way, signals directed toward a specific goal

What are synapnic knobs (aka pre synaptic terminals)?

Synapses from other neurons on surface or dendrites of soma. Can be excitatory or inhibitory

Transmitter vesicles can be

excitatory or inhibitory

What determines whether a transmitter vesicle is excitatory or inhibitory?

Receptor type that is located on the postsynapctic neuron

What causes neurotransmitter release?

Voltage gated calcium channels

Receptor proteins are found on the

postsynapctic neuron

Pre and post synaptic neuron set up

Cation channels are _____ charged so they _____

Negatively charged, so they repel anions

anion channels are ______ charged so they

Positively charged, so they repel cations

Cations are

positively charged (i.e. Na+) excitatory transmitters

Anions are

negatively charged (i.e. Cl-) inhibitory transmitters

Second messenger systems and neuronal changes

prolong posynaptic nueronal changes, want the cell to have a change

Most common second messenger system is

G protein

3 domains of G-proteins

alpha, beta, gamma

G - protein: What happens when transmitter binds to receptor protein?

Alpha subunit separates from complex

G protein: What does alpha subunit do once it separates from complex (4)

1. Opens specific ion channels for prolongation 2. Activates cAMP or gAMP 3. Intracellular enzyme activation 3. Gene transcription

Excitatory receptors open:

Sodium (cation) channels (bring membrane more positive)

Excitatory receptors and ion movement

Decrease of Cl- in, Decrease of K+ out, Increase Na+ in

Inhibitory receptors open:

Chloride (anion) ion channels

Inhibitory receptors and ion movement:

Increases K+ out, Increases Cl- in decreases Na+ in

Inhibitory receptors bring cell membrane

away from positive, more negative

Neurotransmitter responses are (speed and duration)

most acute and short lived

Neurotransmitters are synthesized in the

cytosol of presynaptic terminal

Neurotrasnmitter movement in and out

absorbed into vesicles via active transport recycling - vesicle fuses with with membrane of presynaptic terminal

Acetylcholine is secreted at terminals of:

Motor cortex Basal ganglia motor neurons skeletal muscles preganglionic ANS postganglionic PNS and SNS

Norepinephrine neurotransmitter location

brain stem and hypothalamic neurons

NE controls

activity and mood

NE is usually a(n)_____ neurotransmitter

excitatory

Dopamine location

Substantia nigra - terminate at striated region of basal ganglia

Dopamine is a(n) ______ neurotransmitter

Inhibitory

Glycine location

synapses in spinal cord

Glycine is a(n)_____ neurotransmitter

inhibitory

GABA location (3)

Nerve terminals in 1.spinal cord 2.cerebellum 3.basal ganglia

GABA is a(n) ______ neurotransmitter

inhibiotory

Glutamate location (2)

Presynaptic terminals in sensory pathways of 1. CNS 2. cerebral cortex

Glutamate is a(n) _____ nuerotransmitter

excitatory

Serotonin location

Median raphe of brainstem

Serotonin is a(n) _________ neurotransmitter of _______

inhibitory neurotransmitter of pain pathways

Serotonin controls

mood and sleep

Nitric Oxide neurotransmitter is important for (2)

areas of 1. long term behavior 2. memory

Nitric oxide MOA

synthesized on demand, not stored in vesicles

Neuropeptide neurotransmitters are synthesized by

ribosomes

Neuropeptide size

large

Neuropeptides are packaged and split in

golgi apparatus

Neuropeptides are transported via

axonal streaming

Neuropeptide release (amount and potency)

Small quantities, more potent

Neuropeptides cause

prolonged actions (such as learning and memory formation)

Fatigue occurs when

area becomes over excited and neurons lose excitability

Fatigue manifestations (3)

1. Depletion of neurotransmitters 2. Inactivation of postsynaptic receptors 3. abnormal concentrations of ions

Alkalosis and neuronal excitability

increases neuronal excitability

Acidosis and neuronal excitability

depresses neuronal excitability and can lead to coma

Caffeine and neuronal excitability

increases

Strychnine and neuronal excitability (MOA)

increases excitability by inhibiting inhibitory substances/neurotransmittors

Anesthetics and neuronal excitability

increases threshold for excitation