PNS Organization

Divisions of the PNS

Divisions of the PNS

Autonomic and Somatic

Do spinal nerves have motor or sensory components?

both

fundamental functional units of the nervous system

neurons

Are neuron cell bodies hydrophobic or hydrophilic?

hydrophobic

what is the function of the endoplasmic reticulum?

lipid and protein synthesis

what is the function of lysosomes

digest compounds and convert glycogen to glucose

what is the function of the golgi apparatus

stores formed proteins and lipids

what is the function of microtubules

axonal transport

2 functions of axons

transmission of information, transportation of metabolically important materials

direction from soma to output region (axon)

anterograde

Direction from the axonal end back to soma

retrograde

what cells myelinate axons?

schwann cells

do unmyelinated axons still have associated schwann cells? why?

yes, trophic support

what makes up the neuronal cell membrane?

2 layers of phospholipids

which part of the phospholipids is directed towards the middle of the neuronal cell membrane?

hydrophobic part

Extracellular is more ________ charged than inside

positive

intracellular is more ________ charged than outside

negative

like charges repel each other

electrostatic force

ions tend to move from higher concentration to lower concentration

diffusion force

are diffusion or electrostatic forces typically stronger?

diffusion

Have high concentrations outside of the cell

Na and Cl

Have high concentrations inside of the cell

K and proteins

proteins that are specific to ion type and help control the rate of transport

ion channels

transport requires ATP (ex: sodium/potassium pump)

active mechanisms

a specific molecule attaches to the receptor and opens the channel so ions can move inside

ligand-gated channels

channels that open in response to any mechanical stimulus such as pressure or stress

mechanically gated

channels open only when the membrane potential reaches a threshold

voltage gated

channels that open at rest randomly, ions can pass through in either direction

leakage channels

are there more K or Na leakage channels

K

What does the sodium potassium pump transport

3 Na from interior to exterior and 2 K from exterior to interior

inside of cell becomes less negative

depolarization

inside of cell becomes more negative

hyperpolarization

inside becomes more positive than resting, can create an action potential when added together

excitatory synapse (EPSP)

inside becomes more negative than resting

inhibitory synapse

what can increase speed of propagation?

increased diameter, myelination

propagation of the action potential occurs in __________ direction(s)

both

functions of the myelin sheath

electrical insulator, allows for accumulation of charge at nodes of ranvier, speeds up conduction

in a synapse, the first neuron is the _____________ and the target cell is the ____________

presynaptic neuron, postsynaptic neuron

what are the types of synapses

electrical and chemical

what are the basic steps of synaptic transmission?

synthesis, loading to synaptic vessels, depolarization, spilling into synaptic cleft, binding to polysynaptic receptors, response in polysynaptic cell, removal of neurotransmitter

occurs if the presynaptic vesicles are released at a faster rate than reuptake can recycle them

synaptic fatigue

neurotransmitter reenters the presynaptic axon terminal

reuptake

the dorsal root is ________ while the ventral root is ____________-

sensory, motor

Nerve that is a mix of motor and sensory

spinal nerve

spinal nerves split into __________ that go into ____________

rami, plexus

how does the brachial plexus split (order of divisions)

5 roots, 3 trunks, 6 divisions, 3 cords, 5 branches

the ganglion is on the _______ portion of the cord

dorsal

sensory info travels via __________ fibers to the spinal cord

afferent

a motor neuron and all the muscle fibers that it innervates

motor unit

what is the all or none law?

all muscles in a motor unit contract together when a neuron fires

muscles served by a single spinal nerve root

myotome

area of skin innervated by a single nerve root

dermatome

what are the steps of an action potential

-excitatory synapse is generated which opens up voltage gated Na channels and Na travels inside cell

-voltage gated sodium channels close and potassium channels open

-potassium leaves the cell making it more negative again until RMP is acheived