unti 3

cholinergic, GABA-ergic, Adrenergic

most common- cholinergic

ranked from fastest to slowest- cholinergic, GABA, Adrenergic

names the types of synaptic transmissions

• what is the most common

• rank from fastest to slowest

ACh

what is the neurotransmitter of cholinergic

excitatory

is cholinergic excitatory or inhibitory

nerve impulse Ca+2 to move into terminal, triggers synaptic vesicles to release ACh, ACh binds to postsynaptic receptors (depolarization)

describe cholinergic

GABA

GABA-ergic neurotransmitter?

inhibitory

GABA-ergic excitatory or inhibitory?

nerve impulse triggers release of GABA into synaptic cleft, binds to GABA receptors, lets chloride into the cell, hyperpolarizes, signal stops

describe GABA-ergic

norepinephrine

adrenergic neurotransmitter

excitatory

adrenergic excitatory or inhibitory

nerve impulse releases norepinephrine, binds to transmembrane protein, triggers secondary message system

describe adrenergic

1. injury or damage

2. neurosoma swells, ER breaks up and nucleus moves off to center

3. axon stump sprouts multiple growth processes as severed distal end continues to degenerate (target tissue is releasing Nerve Growth Factors)

4. schwann cells, basal lamina, and neurilemma forms a regeneration tube (like a railroad) that allows neuron to regrow in correct spot

5. once contact is reestablished, the neurosoma shrinks and returns to original size

nerve regeneration

1. ions diffuse down concentration gradient through the membrane

2. plasma membrane selectively permeable and allows some ions to pass easier than others

3. electrical attraction between positive and negative ions

what 3 combined factors effect the resting membrane potential of neurons?

potassium (K+)

because plasma membrane more permeable on K+, meaning that it tends to leak out easier than Na+

membrane is not very permeable to Na+ but still leaks out slightly

which ion (Na+ or K+) has the greatest influence on resting membrane potential (RMP) and why?

Na/K pumps move 3 Na out and 2 K back into cell

pump works continuously in order to compensate for the Na and K leakage

keeps RMP at -70 mV

what is the role of Na/K pump in resting membrane potential (RMP) of neurons?

-90 mV

what is the RMP of muscles

-70 mV

what is the RMP of neurons

action potential:

• irreversible

• nondecremental

Local potential:

• reversible

• decremental (signal gets weaker over greater distance)

• excitatory(make more positive) or inhibitory (make more negative)

compare and contrast action and local potentials

when a muscle contracts without shortening or lengthening (pushing up against a wall)

isometric

when a muscle changes length under constant tension (bicep curl)

isotonic

entirely contained in one area

Intrinsic muscles

acts on designated area but has one attachment elsewhere 

Extrinsic muscles

the muscle that opposes the prime mover, it prevents excessive movement

antagonist

 muscle that prevents movement of bone

fixator

Capillaries branch extensively through the endomysium to reach every muscle fiber

Describe in general terms the nerve and blood supply to skeletal muscles.

Describe aspects of structure, location, or action of a muscle

Explain how the Latin names of muscles aid in visualizing and remembering them.

Some muscles are attached through other ways, such as tendons, fascia, other muscles, or collagen fibers.

Shortcomings of calling attachments origins and insertions

• Tendons- connect muscle to bone 

• Collagen fibers of epi, endo, and perimysium into tendon and then into periosteum and into matrix of bone 

• Aponeurosis- tendon is broad, flat sheet  

• Retinaculum- connective tissue band that tendons from various muscles pass beneath

Indirect bone attachments

tendon is broad, flat sheet  

Aponeurosis

-connective tissue band that tendons from various muscles pass beneath

Retinaculum

• Muscles seem to be coming directly out of bone 

• Little separation between bone and muscle 

Direct bone attachments

whole muscle, fascicle, muscle fiber, myofibril, myofilament

structural hierarchy of skeletal muscle

axon

goes out of cell body

dendrite

goes into cell body

endocrine system

hormones ADH, long distance, circulatory

nervous system

neurotransmitter ADH, short distance, neurons close

central nervous system

brain and spinal cord

peripheral nervous system (PNS)

all the nervous system except the brain and spinal cord, have nerves and ganglions

contain sensory and motor divisions each with somatic and visceral subdivisions

ganglion

a knot like swelling in a nerve where meuron cell bodies are concentrated, in PNS

sensory division

carries signals from receptors to CNS

include somatic sensory division and visceral sensory division

somatic sensory divison

carries signals from receptors in the skin, muscles, bones, and joints

visceral sensory divison

carries signals from receptors from the viscera (hearts, lungs, stomach, and urinary bladder)

motor division

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

have somatic and visceral motor division

somatic motor division

carries signal to skeletal muscles

output produces voluntary muscular contraction and somatic reflexes (involuntary muscle contractions)

visceral motor division

carries signals to glands, cardiac, and smooth muscle

its involuntary responses

contain sympathetic and parasympathetic divison

sympathetic division

in visceral motor divison

tends to arouse body for action

accelerating heart beat beat and respiration, while inhibiting digestive and urinary systems

parasympathetic division

in visceral motor division

tends to have calming effect

slows heart rate and breathing

stimulates digestive and urinary systems

rest and digest

universal properties of neurons

excitability, conductivity, and secretion

excitability in neurons

respond to environmental changes called stimuli

conductivity in neurons

respond to stimuli by producing electrical signals that are quickly conducted to other cells at distant locations

secretion in neurons

when an electrical signal reaches the end of nerve fiber, the cell secretes a chemical neurotransmitter that influences the next cell

functional classes of neurons

sensory neurons, interneurons, motor neuron

sensory neurons

detect stimuli and transmit infor about them toward the CNS

interneurons

most common

lie entirely within the CNS connecting motor and sensory pathways and receive signals from many neurons and carry out integrative functions

motor neuron

send signals out to muscles and gland cells

soma

control center of neuron

axon collaterals

branches of axon

axoplasm

cytoplasm of axon

axolemma

plasma membrane of axon

unipolar

single process leading away from neurosoma

sensory cells from skin and organs to spinal cord

anaxonic neuron

many dendrites but no axon

retina, brain, and adrenal gland

axonal transport

2-way passage of proteins, organelles, and other materials along axon

anterograde transport and retrograde transport

anterograde trasport

movement down the axon and away from neurosoma

uses motor protein kinesin

retrograde transport

movement up the axon toward the neurosoma

uses motor protein dyesin

fast axonal transport

fast anterograde transport - organelles, enzymes, synaptic vesicles, and small molecules

fast retrograde transport-for recycled materials and pathogens- rabies, herpes simplex, tetanus, etc

delay between infection and symptoms is time needed for transport up the axon

slow axonal transport

always anterograde

moves enzymes, cytoskeletal components, and new axoplasm down the axon during repair and regeneration

damaged nerve fibers regenerate at a speed governed it

no because there is no mitosis in nerves

will nerves regenerate if damaged?

neuorglia

protect neurons and help them function

glial cells

structure, protect from pathogens, clean up cellular debris

oligodendrocytes

forms myelin sheaths in CNS that speed up signal conduction

ependymal cells

lines the internal cavities of the brain and secretes and circulated CSF, only in CNS

microglia

wander through the CNS looking for debris and damage, white blood cells of CNS

astrocytes

form supportive framework, form the blood-brain barrier, regulates chemical composition of tissue only in CNS

schwann cells

forms myelin sheath in PNS

satellite cells

surround the neurosoma in ganglia, only in PNS

nodes of ranvier, internodes, initial segment, and trigger zone

segments of myelin sheath

nodes of ranvier

gap between segments of myelin sheath

internodes

myelin-covered segments from one gap to the next

initial segment

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

trigger zone

the axon hillock and the initial segment (play a role in initiating a nerve signal

steps of regeneration

1. injury or damage

2. neurosoma swells, ER breaks up, and nucleus moves off center

3. axon sprouting and growth

4. Schwann cells, basal lamina, and neurilemma form regeneration tube

   1. enables neuron to regrow to original destination and establishes synaptic cleft

5. neurosoma shrinks and returns to its original appearance

6. regeneration is not fast

   1. regeneration of damaged nerve fibers in the CNS cannot occur at all

nerve growth factor

protein secreted by a gland, muscle, or glial cells picked up by axon terminals of neurons

prevents apoptosis

-70

RMP of muscles

-90

RMP of neurons