Lesson 1: Neurons and Neural Communication Flashcards
purpose of the nervous system
to transmit information
- tells what’s going on outside yourself (sensory information)(feeling that it’s getting too hot)
- allows you to access memories and make decisions by transmitting information about the past and current conditions (information processing)(decide to change the temp)
- passes on information to muscles so you can move (motor)(move muscles to walk to thermostat)
basic cell types of the nervous system
neurons (transmit info) and glia (don’t transmit info)
types and functions of glia cells
- astrocytes: transfer from blood to CNS neurons; provide structure
- satellite cells: absord dead cells; regulate nutrients
- oligodendrocites: myelinate axons in Central Nervous System
- Schwann Cells: peripheral nervous system myelination
- ependymal cells: regulate cerbrospinal fluid
- migroglia: remove debris through absorption
general structure of a neuron
- cell body (aka soma): main part of cell containing nuleus
- nucleus: contains DNA
- dendrites: part of neuron that receives info
- axon: part of neruon that sends info
- axon hillock: point at base of soma where action potential is generated
- myelin sheath: insulation covering some axons
- terminal buttons- branching endpoints of axons
neural firing and communication
- synaptic cleft: space in between each neuron
- synapse: the terminal button of neuron 1, the space, and the receptor of neuron 2
- when the neuron fire, it releases neurotransmitters into the synaptic cleft
- the receptors receiving the neuron pick up the neurotransmitter (excitatory/ inhibitory)
resting potential
when the neuron isn’t excited or inhibited
mechanisms of the resting potential
- membrane: a protective covering that separates the inside from outside (like skin)
- selective permeability: some ions can pass through the membrane more easily than others. Membrane has pores that can open or close to let some ions in and keep other out
- polarization: difference in charge between inside and outside (at rest when more negative inside w/ more potassium)
- sodium-potassium pump: maintains polarization by transporting 3 sodium ions out while transporting 2 potassium ions in (K is more negative than Na)
selective permeability (more in depth)
2 major ways to move across membrane:
- passive transport: gradients (gravitate toward opposite; where your kind is less concentrates,seek balance)
- active transport: processes that require energy
2 major stars of show: Sodium and Potassium
forces moving neuron away from resting potential
- electrical gradient: distribution of charge between inside and outside
- concentration gradient: the distribution of ions across the membrane
action potential
- nerve impulse starts when neuron moves from resting potential to action potential
- the polarization reverses and becomes more positive inside the neuron
- hyperpolarization: increased polarization
- depolarization: reduction of polarization toward 0
- threshold of excitation: point that produces a sudden and massive depolarization
- action potential: rapid depolarization and reversal of usual polarization
- all or none law: the amplitude, velocity of an action potential is always the same no matter how intense the initial stimulus was
- frequency can change
- refractory period: neuron is unlikely to produce action potentials (absolute: can not, Na is closed; relative: unlikely, K is open)
myelination and saltatory conduction
- myelinated axons: covered with an insulating substance called myelin sheath (connvey action potentials at super speed; typically found in neurons regulating primary survival processes)
- saltatory conduction: jumping of the action potential from node of ranvier to node of ranvier
processes at the synapse
the action potential is an all-or-nothing process along the axon, but activity in the dendrites and soma are far from all-or-nothing
synaptic cleft
gap between one neuron and the next
pre-synaptic
1st (sending) neuron
post-synaptic
2nd (receiving) neuron
