Synapses, NTs, Circuity Flashcards by michael perna

The purpose of the nervous system

Communication

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Brain—>Target Organ—->Response——>Feedback—–>Brain Etc.

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In order to preserve communication, a message must propagate along each cell (A.P.) and between each cell (synapse)

Nerve Cell—->Nerve cell—-> Nerve cell——> Target Organ

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Na+ Channels do what to the cell membrane?

K+ channels do what to the cell membrane?

Depolarization

Repolarization and hyperpolarization

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Propation in unmyelinated cell

Na and K channels open and close sequentially along the membrane, voltage gated channels located across entire membrane

Continuous Conduction

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Propagation of action potential involves ____ coated nerves,

A lipid coating on nerve axons that serves as an insulator

Myelin

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Propagation of A.P. along nerve cells is what type of conduction

(to jump in Spanish)

Saltatory Conduction

Saltar

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Areas of no myelin that contain voltage gated channels only in nodes

Nodes of Ranvier

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Action potential is generated at nodes, ion current travels rapidly between nodes. Regenerate action potential at next node

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In the myelinated or unmyelinated nerve, the action potential travels from the beginning to the end of the nerve. When it reaches the end, it must enter the

synapse

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Why are myelinated nerves advantageous?

Speed of conduction

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Junction between nerve and effector cell. Permits and preserves communication between cells.

In skeletal muscle, what is the synapse?

Synapse

Neuromuscular Junction

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In the nervous system, a synapse exists between 2 nerves.

The neuron that submits action potential to the synapse is called the

Pre-synaptic neuron

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The neuron that receives the action potential from the synapse

Post-synaptic neuron

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Anatomical arrangement that is the most common, the axon of the pre-synaptic neuron synapses with the dendrite of the post-synaptic neuron.

Axo-Dendritic (axo-somatic) synapse

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Anatomical arrangement where the axon intersects with another axon and may go in two directions

Axo-axonal synapse

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Anatomical arrangement with 2 dendrites

Anatomical arrangement with a dendrite and a body

Dendro-Dendritic Synapse

Dendro-somatic synapse

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Communication between neurons can be modified and protected by the surrounding

What’s the most common type of these cells?

Glial Cells

The astrocyte

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These type of glial cells absorb extra K+ ions from neurons, recapture and recycle NTs, and are connected to each other by gap junctions

Astrocytes

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With what chemical do astrocytes communicate with one another via their gap junctions?

Ca2+

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Functional arrangement of gab junctions that are found in the brain. There is ion flow from one cell to another

Electrical Synapses

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The gap junction proteins in gap junctions of pre synaptic and post synaptic membrane

Connexons

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Synapse with a synaptic cleft where there is no physical contact between cells and no ion flow between cells

Chemical Synapses

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These type of synapses use a NT that is synthesized and stored by the presynaptic nerve in synaptic vesicles

Chemical Synapses

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Where did chemical synapse occur where we've studied?

Neuromuscular junction

How are chemical synapses in the brain different from those in skeletal muscle?

They go from nerve to nerve, not nerve to muscle

As before, the plasma membrane of the terminal bouton of the pre-synaptic cell contains what type of voltage gated channels?

Ca2+ voltage gated channels

Is intracellular of extracellular Ca2+ higher before AP arrives?

Extracellular is higher

When A.P. arrives to the chemical synapse, what happens

Channels open and Ca2+ diffuses into terminal bouton

What does Ca2+ flow into terminal bouton cause?

Synaptic Vesicle migration and fusion with plasma membrane

How does the NT from the terminal bouton in chemical synapses enter the synaptic cleft?

Diffusion

What happens to the NT wants it reaches post synaptic membrane?

Binds with receptors

What does binding of NTs to receptors on post synaptic neuron membrane initiate? Which is often followed by...

Graded potential Action potential

The only place in the body where you see action potential always following graded potential in post synaptic cell is the..

Neuromuscular junction

The three methods of degradation and removal of NT to prevent inappropriate graded/action potential initiation

Pre-synaptic neuron reuptake (good for recycling) Glial cell uptake Enzymatic degradation and diffusion of components

NT type that occurs in NM junction, widespread throughout cerebral cortex, brainstem and hippocampus, therefore possibly memory (Chemical classification)

Acetylcholine

NTs made from amino acids (protein based) are called

Biogenic amines

A type of catecholamine involved in coordination of body movements, feel good NT (love), deficient in Parkinson's, excess in schizophrenia

Dopamine

Important catecholamine NT for sleep/wake cycle, attention, feeding, and feeling good

Norepinephrine

Catecholamine that is similar to norepinephrine, considered the same

Epinephrine

A type of Indolamine that is important in the sleep/wake cycle, appetite, mood regulation (deficient in depression)

Serotonin

An indolamine that is important in wakefulness, appetite, learning and memory drowsiness from anti ___ drugs (benadryl)

Histamine

In general, what to biogenic amines regulate?

Biological clock | Mood/behavior

This recreational drug can bind to biogenic amine receptors and cause hallucinations

LSD

amino acids in nervous system have specific or general roles?

General

2 Amino acids in CNS that are inhibitory

GABA | Glycine

Amino acid in CNS that is excitatory

Glutamate

One of two peptides in the CNS that is an important mediator of pain transmission in the PNS

Substance P

One of two peptides in the CNS that are natural opiates, blocks pain and inhibits substance P

Endorphins

An excitatory or inhibitory bolecules; present in the CNS and PNS; important for pain modulation

ATP (purine)

The nitrogen base within ATP that is inhibitory on the brain and induces sleep. Caffeine blocks its receptors. We're tired because there is free adenosine that was used by ATP

Adenosine

A gas molecule involved in learning and memory and strengthening synapse formation

Nitric Oxide

NT that causes action potential on a post-synaptic neuron

Excitatory

NTs that cause suppression of action potential on post-synaptic neuron

Inhibitory

Excitation or inhibition is normally determined by what?

The receptor at the post-synaptic membrane

Excitation or inhibition can be accomplished by two means

Direct and Indirect

These type of receptor opens ion channels directly after binding to the NT. Ex: Acetocholine

Direct Receptor

Channel linked receptors (direct) are seen when rapid response is needed

NM Junction

This type of receptor uses second messengers to open ion channels and also initiate other intracellular effects ex:: g-protein linked receptor

Indirect Receptor

Post synaptic potential that is often located on dendrites, and often involves sodium ion channels

EPSP - excitatory post-synaptic potentials

Type of post synaptic potential that is often in the cell body, open CL- channels (Cl-enters cell and hyperpolarizes) Action potential cannot occur

Inhibitoory post-synaptic Cell

Most of the synapses in the brain are electrical or chemical?

Chemical

Since chemical synapses are more complicated, slower, and take more energy, why are they more abundant in the brain?

Chemical synapses allow discrete control | Electrical impulses are fast but uniform

Type of summation when multiple impulses are sent rapidly to the post-synaptic neuron ensures suppression or excited (inhibitory or excitatory)

Temporal

Type of summation where several pre-synaptic neurons send impulses to the post-synaptic neuron simultaneously Important in chemical synapse Can have different types of synapses depending upon receptor, good for control

Spatial

An amplifying type of circuit of neurons different events occur because of one single event

Divergent

A concentrating type of circuit of neurons See, hear, smell, touch = love (one output)

Convergent

A reverberating type of neural circuit Goes round and round fro usually a number of hours Ex) Sleep and wake, found in brain stem

Oscillating

Type of processing that is typically a reflex arc

Serial-sensation

Higher level mental functions are often performed by what type of processing?

Parallel Processing

Rapid, automatic responses to stimuli that are serial-sensation processing

Reflex arc

Components of a reflex arc (6)

``` Stimulus Receptor Sensory neuron Integration center Motor Neuron Effector ```

The component of a reflex arc that translates a stimulus into A.P.

Receptor

The component of a reflex arc that carries the A.P. to the CNS

Sensory Neuron

The component of the reflex arc that is the CNS

Integration Center

The component of the reflex arc that carries A.P. to the effector (muscle)

Motor Neuron

The component of the reflex arc that executes the appropriate response

Effector

What's an example of a stimulus that we don't have a receptor for so we don't see when it's effecting us?

UV light

Name the two type of reflexes

Visceral | Somatic

Type of reflex that involves glands

Visceral

Type of reflex that involves skeletal muscles | This includes spinal reflexes - stretch deep tendon, crossed extensor, superficial

Somatic

A somatic reflex that involves muscle spindles embedded in skeletal muscle, made of intrafusal fibers each skeletal muscle contains many spindles, not just one

Stretch Reflex

More muscle spindles means more.... Flexor pollicis muscle has more or them that latissimus dorsi

control

Which fibers are in the non-contratile center? Which fibers synapse at contractile ends?

Sensory Fibers Gamma Motor Fibers

When large skeletal muscle is stretched, the spindle is also stretched. Stretch irritates the ____ fibers which fires AP to the spinal cord

Sensory Fibers

At the spinal cord, there is a synapse with a ______ neuron supplying skeletal muscle and antagonist muscle

Alpha motor Neuron

What action does the stimulated/stretched muscle have? What action does that antagonist muscle have?

Contraction Relaxation

Spindle tension is maintained by APs from....

Gamma motor neurons

Spindle tension must be maintained at all times so that when the skeletal muscle is stretched, the spindle fiber is stretched enough to irritate the sensory nerves. If the spindle becomes loose, than no mechanical irritation of the sensory nerves will occur

The deep tendon reflex area with collagen fibers in a tendon with sensory nerve endings attached. They synapse in the spinal cord.

Golgi Tendon Organ

In response to stretch of a tendon, the GTO is stimulated and AP fires off along sensory nerve. Synapse with alpha motor neurons of both stretched and antagonistic muscle. What happens to stretched muscle? What happens to antagonist muscle?

Stretched muscle relaxes Antagonist muscle contracts

What does the deep tendon reflex with the GTO prevent? What type of control?

Muscle tearing Postural Control

Reflex of withdrawal due to a painful stimulusm occurs BEFORE concious perception of a stimulus

Flexor reflex

Reflex of ipsilateral withdrawal and contralateral extension ex) walking along beach, step on sharp seashell, withdraw foot and extend other foot to keep upright (postural)

Crossed extensor

Two type of superficial reflexes

Plantar | Abdominal

The superficial reflex that tests integrity of L4-S2 nerve roots If normal it will cause (only if babies walk) If abnormal, it will cause....

Plantar Reflex Downward flexion of toes (plantar flexion) (opposite if baby doesn't walk) Babinski sign

Superficial reflex that tests the integrity of T8-T12. Normal =

Abdominal Superficial Reflex umbilical moves to stimulated side due to abdominal muscle contraction