organization of PNS

the fundamental functional unit of the nervous system

neuron

membrane of the cell body

hydrophobic (keeps water in and keeps water out)

binds together a cytoplasm

cytoplasm

cytosol, the aqueous part of the cytoplasm

nucleus

nucleolus at the center

chromosomes for the coded production of proteins

endoplasmic reticulum function

lipid and protein synthesis

rough ER

protein synthesis

rough due to ribosomes

smooth ER

lipid synthesis

ER is made of tubes that

isolate, modify, store, and transport the proteins and lipids

lysosomes

digest compounds

glycogen to glucose

part of the axoplasmic transport system

golgi apparatus

stores the formed proteins and lipids

microtubules

axonal transport

relays structures such as neurotransmitter vesicle down the axon to the output zone

axons serve two functions

transmission of information: propagation of action potential

transportation of metabolically important materials to and from the soma to the axonal end

anterograde

from the soma to the output region

- neurotransmiiter vesicles

retrograde

from axonal end back to soma

myelinated axons

Schwann cells myelinate axons by investing them with up to 300 concentric layers to form the myelin sheath

unmyelinated axons

No myelin sheath, but are associated with and enveloped by Schwann cells, which provide trophic support

the neuron cell membrane has what type of layers

two hydrophobic phospholipid layers

two types of forces that guide movement of ions

electrostatic force

diffusion force

electrostatic force

like charges repel eachother

diffusion force

ions tend to move from higher concentration to lower concentration

diffusion forces tend to be ____ than electrostatic forces

stronger

mechanisms for ion transport

ion channels

active mechanisms

types of ion channels

ligand-gated

mechanically gated

voltage gated

leakage

ligand gated

made of multiple proteins

ligand molecule attaches to the receptor and opens the channels

mechanically gated

opens in response to any mechanical stimulus such as pressure or stretch

voltage gated

opens when the membrane potential reaches threshold

leakage channels

open at rest randomly

which one is more common: K+ leakage or Na+ leakage channels

K+