Psychoactive substances chapter 2

Types of neruons

Sensory, Motor, Interneruons

What does a sensory neuron do?

detect changes in internal or external enviornments

What does a motor neuron do?

Control muscular contraction or glandular secretion

What are the two types of interneruons?

Local and relay

What is a local nueron?

Forms circuits with nearby neurons

What is a relay neuron?

connect circuits of nearby neurons in one region of the brain to another region of the brain

Whats the central nervous system?

The brain and spinal cord

Whats the peripheral nervous system?

the nerves outside the brain and spinal cord and the sensory organs

What are the structures of a neuron?

soma, dendrite, axon, terminal button

What do the dendrites do?

acts as a receiver of information and transmits the information to the cell body

What does the axon do?

The axon is covered with myelin and carries an action potential

What do the terminal buttons do?

Release neurotransmitter

What are the three types of nuerons?

Bipolar, unipolar and multipolar

What does the membrane of a cell contain/do?

Boundary of cell and proteins

What is the cytoplasm?

Jelly-like fluid, has mitochondria, extract energy from nutrients, synthesize ATP, has their own genetic material, replicate independently of the rest of the cell

What is the nucleus?

Has chromosomes which have strands of DNA and contain genes which code for proteins

What are three components of proteins?

Cytoskeleton, enzymes, microtubules

What are the two ways of axoplasmic transport?

Anterograde is cell to terminals

Retrograde is terminal to cells

What are the three types of supporting cells in the CNS?

Glia cells

What are the three types of glia cells?

Astrocytes, oligodendrocytes, microglia

What do astrocytes do?

Control chemical composition around neurons, processes wrap around neurons and blood vessels, help nourish neurons (convert glucose from the blood stream to lactate and store glycogen), act as glue, surround and isolate synapse and remove debris via phagocytosis.

What do oligodendrocytes do?

produce myelin around the axon

what do microglia do?

phagocytes and protect the brain from invading organisms

What are the supporting cells in the PNS?

Schwann cells

What do schwann cells do?

Make myelin sheaths for the PNS. chemical composition for PNS and CNS is different

Blood-brain barrier

Selectively permeable, more permeable in some areas (area postrema), blue dye was injected into the blood but didnt show up in the CNS

What is the resting potential of a membrane?

-70 mV

What is depolarization?

a reduction in the size of the membrane potential, action potential gets triggered

What is hyperpolarization?

an increase in the membrane potential

When is an action potential triggered?

At the threshold of excitation

What are the two forces?

The force of diffusion and the force of electrostatic pressure

What is the force of diffusion?

highly concentrated wants to go to low concentration, chloride and sodium want to go in the cell and potassium wants to come out

What is the force of electrostatic pressure?

opposite charges attract, like charges repel

Potassium ions

Force of diffusion pushes out, electrostatic pressure pushes in

Chloride ions

force of diffusion pushes in, electrostatic pressure pushes out

Sodium ions

force of diffusion pushes in, electrostatic pressure pushes out

Sodium-potassium pump

3 sodium out, 2 potassium in, uses energy, keeps concentration of Na+ low inside the cell

All or none law

An action potential either occurs or does not occur. Always the same size even when it splits

rate law

a strong stimulus will cause a neuron to fire at a fast rate and a weak stimulus will cause a neuron to fire at a slow rate

Saltatory conduction

action potential moves under the myelin, regenerated at the node of ranvier, uses less energy, faster conduction

types of synapses

Axodendritic (on dendrite), axosomatic (on soma), axoaxonic (on axon)

synaptic cleft

gap between two neurons that allows for communication

synaptic vesicles

contains neurotransmitter

omega structure

synaptic vesicles fused with the membrane

postsynaptic receptors

Binds to the neurotransmitter that the presynaptic neuron releases

Ionotropic receptors

neurotransmitter will only bind to that specific receptor and will open the ion channel. fast acting short lasting.

Metabotropic receptor

neurotransmitter needs a G protein in order to open the ion channel. slow acting long lasting. turns genes on and off

postsynaptic potentials

excitatory postsynaptic potential (EPSP) and inhibitory postsynaptic potential (IPSP)

EPSP

during depolarization, increases the likelihood of firing

IPSP

during hyperpolarization, decreases likelihood of firing. stops neurons from firing and stops communication

termination of postsynaptic potentials

Reuptake: transmitter gets taken off the receptor, gets brought back to the presynaptic and then gets repacked

Enzymatic deactivation: enzyme breaks down a neurotransmitter. ACh by AChE

Autoreceptor

bind to their own neurotransmitter so the cell will stop releasing neurotransmitter. If this doesnt happen apoptosis will happen to the cell

axoaxonic synapses

presynaptic inhibition: decrease amount of neurotransmitters

presynaptic facilitation: increase amount of neurotransmitters

Neuromodulator

Doesnt cause EPSPs or IPSPs. usually hormones, secreted by endocrine glands, distributed via blood stream, target cells contain receptors