PLTW HBS Neurons

neuron

transmit electrial impulses for communication within the nervous system

glial cell

support, nourish, protect neurons, maintain homeostasis

cell membrane

controls movement of substances insides and outside of the neurons

cell body

contains nucleus, integrates signsals, controls cellular activities

nucleus

contains DNA and regulates gene expression

dendrites

recieves signals from other neurons

axon

transmits electrial signals away from the cell body and other neurons

axon terminals

release neurotransmitters to communicate with other cells

myelin sheath

insulates the axon, speeds up nerve signal transmission

nodes of ranvier

gaps in myelin sheath where action potentials are regenerated

schwann cell

produce myelin in PNS

synapse

junction where neurons communicate with each other or other cells

neurotransmitter

chemical messengers that transmit signals across the synapse

ependymal cells

lines ventricles of the brain and produces cerebral spinal fluid

oligodendrocytes

form myelin in CNS, speeds up transmission

satellite cells

provide support and nutrition to cells in PNS

astrocytes

maintain blood-brain barrier, support neuron function, regulate blood flow

microglia

act as immune cells of CNA, clearing debris

what are the differences between neuron and glial cells? how do they work together in the nervous system?

neurons conduct electrical impulses while glial cells provide structure, protection, and nourishment

multipolar neuron

CNS, efferent division of the PNS, common

bipolar neuron

PNS, afferent, rare

pseudounipolar

PNS, afferent, common

unipolar

afferent division of PNS, common, rare in vertebraes

what is the difference between efferent and afferent neurons?

afferent neurons carry sensory information to the PNS while efferent neurons transmit minor commands from the CNS to muscles and glands

sensory neuron labeling

location: sensory organs (skin, eyes, ears)

functions: afferent, transmit sensory info to CNS

usual structure: pseudounipolar or bipolar

interneuron labeling

location: CNS

functions: integrate information and relay signals between sensory and motor neurons

usual structure: multipolar

motor neuron labeling

location: CNS

functions: efferent, leads to muscles or glands

usual structure: multipolar

how are all 3 neurons involved when you leg backs up into a cactus?

sensory: detects pain from cactus and sends sign to spinal cord

interneurons: in the spinal cord, processes pain sign and sends a response

motor: sends sign to muscles in your leg to move away from the cactus

how is the electricity in an action potential generated?

an action potential is generated by a rapid change in the membrane potential of a neuron caused by the movemtn of ions (sodium and potassium) across the cell membrance through voltage gated ion channels, creating a temporary electrial signal that travels along the neuron

what causes the inside of the membrance to reverse charge and begin the action potential?

the inside of a neurons membrance reverses charge and initiates an action potential when a sufficient depolarization occurs, causing voltage gated sodum channels to open, allowing a rapid influx of positively charged sodium ions into the cell, flipping the membrance potential from negative to positive

saltatory conduction

conduction through myelinated nerve fibers

how does saltatory conduction influence the speed of signal propagation?

causes the action potential to jump from node to node and conserves energy for the axonw

why is ca2+ needed for one neuron to communicate with another neuron?

calcium is the main second messenger that helps to trasmit depolarization status and synaptic activity to the biochemical machinery of a neuron

what do we call the synapse between a neuron and muscle?

a neuromuscular junction is a synaptic connection between the terminal end of a motor nerve and a muscle

T or F: when you learn something new, you grow new neurons.

false. when you learn something new you do not grow new neurons but instead your neurons form new connections between existing neurons, called synaptogenesis.

explain how neurons convey information using both electrial and chemical signals

neurons convey information using a combination of electrial signs within the neuron itself, traveling along the axon as an action potential, and chemical signals at the synapse where one neuron communicates with another, releasing neurotransmitters that bind to receptors on ther recieving neuron, effectively translating the electrial signal into a chemical one to cross the synaptic gap

step 1

the resting membrane potential is usually around -70mV

step 2

a stimulus is applied to the cell, causing the membrane potential to rise

step 3

after stimulation, the neuron reaches what is known as its threshold membrance potential (-55mV)

step 4

when threshold is reached, a large number of sodium channels open, allowing positively charged sodium ions into the cell. this causes depolarizaiton of the neuron as the membrane potential rises to 0 and then becomes positive

step 5

the action potential reaches its peak. sodium channels close and potassium channels open, which allows potassium to flow out of the cell

step 6

with potassium channels open, the relative voltage inside the cell falls in a process called repolarization, and the neurons membrane potential drops back toward resting potential

step 7

the open potassium channels cause neuron to overshoot resting potential and the cell becomes hyperpolarized, meaning the membrane potential has dropped below its resting potential

step 8

the potassium channels close and the sodium-potassium pump allows the membrane to return to resting membrane potential, ready to be activated again