Biological Psychology Exam #1

What are the functions of a neuron?

Carry sensory info into the spinal cord and brain, carry commands to our muscles and organs, responsible for our thoughts, feelings, and actions

What are the types of neurons?

Motor, sensory, and interneurons

Function of motor neurons?

carries commands from the brain and spinal cord to the muscles and organs

Function of sensory neurons

carries information from the body and the outside world to the brain and spinal cord

Function of interneurons?

connect one neuron to another

Dendrites

receives information from other neurons

cell body

filled with cytoplasm (liquid), nucleus containing cell's chromosomes and other organelles

axons

carries information to other areas, wrapped in myelin sheath

axon terminals

filled with vesicles (tiny sacs of neurotransmitters), which are released to communicate with other neurons or cells

synapse

the connection between neurons, consisting of the presynaptic neuron, postsynaptic neuron, and synaptic cleft (tiny gap) in between

What is the general "flow" of information?

Information received by dendrites and cell body. Information is sent down the axon to the axon terminals. Axon terminals release neurotransmitters, neurotransmitters travel across the synaptic cleft, and influence the next cell or neuron

What is the neural membrane made up of?

lipids and proteins

What is selective permeable?

allowing certain things to pass through

Which part of the lipid bilayers is hydrophobic?

Tails

Which part of the lipid bilayer is hydrophilic?

head

What is the purpose of proteins?

to allow specific ions to pass through. act as channels, receptors or pumps

Purpose of the lipid bilayer?

creates a barrier that separates the inside of the neuron from the outside

Ion channels

proteins embedded in the cell membrane- only allow certain ions through

The different ion channels?

ligand gated ion channels and electrically gated

Ligand gated ion channels

opened by ligands (neurotransmitters or hormones)

Electrically gated ion channels

opened by changes in electrical potentional

When are most ion channels closed?

at rest

What is electricity?

the flow of electrons from one atom to another

difference in ionic charge between 2 areas

Ions

tiny particles with a positive or negative charge

What is the force of diffusion?

ions want to move from places where they are very concentrated to places they are less concentrated (down their OWN concentration gradient)

What is electrostatic pressure?

ions want to move towards areas that have the opposite charge as them (down their electrical gradient)

At rest, what does the outside of a neuron have?

Sodium and Chloride

At rest, how are the ions dispersed outside of the neuron?

There is more positive than negative. Na+ > Cl-

At rest, what does the inside of a neuron have?

Potassium and organic ions

At rest, how are the ions dispersed inside of the neuron?

More negative ions than positive. A- > K+

What is the potential of the inside of a neuron at rest?

-70 mV

What is maintaining the resting potential?

force of diffusion, electrostatic pressure, and sodium-potassium pump

Explain A-

they are inside of the cell, however they want to move outside of the cell but are too large to move through the neuronal membrane

Explain C-

"repelled" by the negative charge of the A- and stays outside the cell

Explain K+

want to diffuse out the cell due to the force of diffusion

Explain Na+

wants to diffuse into the cell based on both the force of diffusion and electrostatic pressure

FUnction of Sodium-Potassium pump?

3 Na+ ions out for every 2 K+ ions it brings in. Uses ATP

What is a local potential?

dendrites or cell body of a neuron is stimulated by something, it causes a small shift in polarity in the surrounding area; Will die out and be isolated to specific area, unless threshold potential is reached

Depolarization

less negative; moves towards 0 mV

Hyperpolarization

more negative; farther away from 0 mV

Threshold potential

when a cell's membrane potential reaches -50 mV to - 55 mV

What happens when a cell membrane reaches threshold potential?

voltage-gated sodium ion channels open in the neuron's axon open, triggering an action potential

Action potential

rapid depolarization in membrane potential

What is the first step of an action potential?

local potential in an area reaches threshold causing voltage-gated Na+ ion channels to open

What is the second step of an action potential?

Na+ rapidly rushes into the cell, causing the inside of the cell to depolarize and have a positive voltage (30-40 mV)

What is the third step of an action potential?

Voltage-gated sodium ion channels sense depolarization and close; Voltage-gated potassium channels are triggered to open

K+ rushes out of the neuron, decreasing the membrane potential back towards -70 mV

What is the fourth step of an action potential?

area of neuron "resets". Displaced ions outside neuron diffuse into surrounding fluid. Displaced ions inside neuron are reset by sodium-potassium pump

Absolute refractory period

during the period of extreme depolarization and "re"- polarization, it is impossible for the area to have an action potential

Relative refractory peirod

another action potential is possible, but only by a larger stimulus than before

What is myelin?

fatty tissue that wraps around an axon

Why is myelin important?

Less action potentials + increased speed down the axon

Nodes of Ranvier

gaps in the myelin

Saltatory conduction

action potentials "jump" over myelin and occur at the Nodes of Ranvier

Local Potential vs. Action potential

Local: Graded, incremental response. Dies out over a short distance

Action: "All-or-nothing". Travels down the entire axon without changing the size

What are the steps after the action potential arrives at the axon terminal?

It triggers opening on calcium ion channels. Calcium rushes into the axon terminal. Calcium causes vesicles to exit the presynaptic neuron through exocytosis

Exocytosis

vesicles "fuse" with neuronal membrane. Contents (neurotransmitters) released into synaptic cleft

Excitatory input

makes action potential more likely to happen

inhibitory post-synaptic potential

makes action potential less likely to happen

Reuptake

process in which neurotransmitters are reabsorbed back into the presynaptic neuron

What are the various ways the synaptic cleft are cleaned up?

Reuptake, astrocytes dispose of some, and can be broken down into parts and reused

Rate Law

strength of a stimulus is communicated by the rate that a neuron has action potentials

Spatial summation

combined input of stimuli at different parts of the dendrite and cell body

Temporal summation

combined input of stimuli occurring close in time to each other

What determines the rate of law?

whether stimuli a neuron receives is inhibitory or excitatory

Oligodendrocytes are a type of glial cell that support neural function by…

wrapping neuronal axons in the brain and spinal cord in myelin

Which is true of the ionic composition of a neuron at rest?

There is more sodium (Na+) on the outside of the neuron compared to the inside..

When the area inside of a neuron becomes depolarized to around -50 mV, what is the first thing that occurs to trigger an action potential?

voltage-gated sodium ion channels open

A local potential…

"dies out" over a short distance

During the _ it is impossible for the area of the axon to have another action potential. During the __ , it is possible for the area to have another action potential, but a larger stimulus is needed.

absolute refractory period; relative refractory period

If the membrane potential of a neuron is -70 mV, the neuron is at its…

resting potential

Choose the correct order of events that occur after an action potential travels down a neuron's axon to the axon terminal:

1. Neurotransmitters bind to the postsynaptic neuron

2. Vesicles undergo exocytosis

3. Reuptake and other disposal mechanisms of neurotransmitters

4. Calcium ion channels are opened and calcium rushes into the axon terminal

4, 2, 1, 3

Which is not a way that neurotransmitters are "cleared away" from the synaptic cleft?

Exocytosis

Information is conveyed at a neural level by…

the rate at which a neuron fires action potentials

Which of the following influences a neuron's likelihood of generating an action potential?

Spatial summation and Temporal summation

What is a drug?

something that impacts how the body is functioning by enhancing or decreasing the effects of neurotransmitters

Agonist

mimicking or enhancing the effects of neurotransmitters

Antagonists

blocking or decreasing the effects of neurotransmitters

Psychoactive drugs

drugs with psychological impact

Function of agonists?

increase neurotransmitter release, mimic neurotransmitter activates receptors on the post-synaptic neuron, inhibit enzymatic breakdown, inhibit reuptake

Function of antagonist?

blocks making of neurotransmitters, blocks release of neurotransmitters, blocks post-synaptic receptors

What are the classes of drugs?

Opioids, depressants, stimulants, and psychedelics

Opiates

drugs derived from the poppy flower

Opioids

synthetically made drugs that impact the same receptors as opiates

Examples of opioids

heroin and oxycodon/oxycontin

Mechanism of action of opioids and opiates?

Agonist: Mimics endogenous opioids such as endorphins

When are opioids generally used?

released during stress/pain. Inhibit and ease pain

Acute impact for opiates/opioids?

Analgesic (pain relief), can suppress cough, Hypnotic (induces sleep), feelings of euphoria

Morphine

used in clinical settings to treat pain

Codeine

used as a cough suppressant

Risk and Fatalities of opiates/opioids?

highly addictive due to immediate impact and feelings of euphoria

high rates of overdose and death

Impact on breathing centers in medulla + high rates of tolerance

What is the moderate withdraw of opiates/opioids?

flu like symptoms