EXAM 2💔

nervous tissue main cell

neuron

how do neurons create electricity

by communiciating with ions that send electrical signals

cortex

integration of information, thinking, memory, consious

brain stem

subconscious activities - respiration, heartbeat, salivation, physiological response to emotions

spinal cord

walking, other repetetive movements ( reflexes) information transmission reflexes such as pain or postural reflexes - local blood flow

reflex

unconscious response to stimulus

capillary

smallest blood vessel; brings nutrients and oxygen to the tissues

astrocyte

a star-shaped glial cell that wraps around walls of blood vessels to restrict transport of big molecules (CNS)

Satellite cells

surround neuron cell bodies, wrap around blood vessel walls and restrict transport of large molecules in PNS

microglial cells

type of neuroglial cell that phagocytizes bacterial cells and clears debris. Found in both the PNS and CNS. this cell is immovable and cannot move- only catches bacteria nearby.

ependymal cells

(made of epithelial cells) produce cerebrospinal fluid and line and protect brain from contact. Covers cavities and ventricles in brain. (CNS and PNS)

Oligodendrocytes

Type of glial cell in the CNS that wrap axons to form and maintain a myelin sheath. Also functions as electrical insulation for the cell. Cannot regenerate damaged neuron.

Schwann cells

schwann- electrical insulation

Satellite- Keep concentrations in ECF

can fix damaged neurons (PNS)

Astrocytes

CNS

Satellite cells

PNS

microglial cells

PNS , CNS

Ependymal cells

CNS, PNS

Oliogodendrocytes

CNS

Schwann cells

PNS

Axon hillock

action potential starts here

axon terminal

end of axon

axon

sends signal

Dendrites

Receive signals from other neurons.

multipolar neuron

a nerve cell that has many dendrites and a single axon (most abundant in bodies- in skeletal muscles)

bipolar neurons

one axon and one dendrite (retina of eye or inner ear )

unipolar neuron

dendrites and axons are fused together; bodies in the ganglia (located in skin-senory receptor for touch and pain)

A node of Ranvier (myelin sheath gap)

A gap between successive segments of the myelin sheath where the axon membrane is exposed.

polar

molecule likes water

apolar

molecule hates water

channels

doors on plasma membranes-opening to move in & out

ions

positively and negatively charged atoms

electricity

only way that neurons can move- if molecules are charged(ions) and can move

neurons communicate via

synapses

electrical synapse

signal passes in both directions; ion channels between cells (gap junctions)

chemical synapse

signal passes only in the forward direction; via neurottansmitter release

plasma membrane

The membrane at the boundary of every cell that acts as a selective barrier, thereby regulating what comes in and out of the cell.

extracellular environment

outside the cell - hydrophillic

intracellular environment

inside the cell - hydrophillic

plasma membrane is

hydrophobic

glucose, ions, amino acids

Which of the following molecules will NOT permeate through a cell membrane?

difference of electrical charges

difference in potential

two ions involved in sending message

sodium and potassium

action potential

the electrical signal generated at the level of the axon hillock that is sent to the next neuron

Neurotransmitters

chemical substances that transmit signal through synaptic cleft

synaptic cleft

a gap into which neurotransmitters are released from the axon terminal

in order to stop the signal between neurons or stop neurotransmitter

three ways - diffusion, reuptake, or enzymatic degradation

Reuptake

process by which neurotransmitters are taken back into the synaptic vesicles

diffusion

neurotransmitter goes away on its own though synaptic cleft after binding

synapse

where neurons communicate with each other

enzymatic degradation

enzymes break down neurotransmitters

Exocytosis

process of releasing neurotransmitter

endocytosis

neurotransmitter goes back inside

excitatory neurotransmitters

excite the next cell into firing ( sodium channels open or chloride or potassium channels closed , or both)

inhibitory neurotransmitters

inhibit the next cell from firing ( sodium channels closed , or potassium or chloride channels open, or both)

2nd messenger (after metabotropic receptor)

activates enzymes. opens or closes channels; slow process

Leaky ion channel

channel is always open

voltage gated channel

closed, electrical stimulus can open for passage once the ions begin to move.

chemically gated channels

needs a molecule that binds to a receptor to open

mechanically gated channels

(closed) can be open with a mechanical stimulus

sactatory conduction

jumps, not continuous

in axon hillock- two ions that start

sodium and potassium

action potential

electrical signal- moving ions (Na+ , K+)

Oligodendrocytes

provides insulation (electrical) - produce myelin protein

myelin sheath

allows neurons to work - protects electrical signal

multipolar neuron

multiple dendrites and one axon

bipolar neuron

one axon and one dendrite

unipolar

axon and dendrite fused together

synapse

a junction between two neurons where a signal is transmitted

synapse cleft

The gap between an axon terminal of a neuron and the next cell it communicates with.

neurotransmitter goes to

dendrites (receptors)

ionotropic receptor

Ion channel that opens to allow ions to permeate the cell membrane under specific conditions- rapid response

metabotropic receptors

receptors that are associated with the 2nd messenger synthesis and G proteins (slow response)

2nd messenger

activates enzyme to open or close channel

acetycholine

a neurotransmitter that enables learning and memory and also triggers muscle contraction

Acetylcholine function

Can be excitatory or inhibitory

CNS (cortex) parasympathetic, neuromuscular junction (contraction of muscles

Acetylcholine antagonist and agonist

Antagonist = botulinum toxin inhibiting release/ curare inhibiting receptor binding

Agonist = nicotine binding to ACH receptors

Norepinephrine

A neurotransmitter involved in arousal, as well as in learning and mood regulation

Norepinephrine function

Given during shock to increase blood pressure

depends on receptor type-

CNS (brain stem, limbic systemc sympathatic branch)

-relaxes smooth muscle around bronchi

-contracts smooth muscle around blood vessels

Norepinephrine is enchanced by

amphetamines (agonist) , and antidepressants and cocain block release (antagonist)

dopamine

A neurotransmitter associated with movement, attention and learning and the brain's pleasure and reward system.

dopamine function

CNS- substantianigra , indirect motor pathways

-some sympathetic neurons

dopamine antagonist and agonist

amphetamines & L dopa enchance release (agonist )

antiphyschotics or promethazine block release (antagonist)

Histamine

release of allergy cells

histamine function

wakefulness, pain sensation, inflammatory response

Both cns and pns depending on receptor

Subtance P

pain transmission (sensory & enteric neurons)

(neurons produce this for pain)

endorphins and enkephalins

inhibitory (CNS) brain, hypothalamus, limbic system