PSY 201 (BLU) EXAM 1 CH 2-3

Function of the phospholipid bilayer

it is a selective barrier that protects the cell and limits the movement of ions

Function of ribosomes

they are sites of protein synthesis

Function of astrocytes

glial cells in central nerv system that provide structural support for neurons throughout the brain and spinal cord by holding neurons in place, and regulate the amount of neurotransmitters around synapses and participate in important metabolic processes that support neuronal activity

Function of oligodendrocytes

glial cells in central nerv system that form the myelin sheath around axons in the central nervous system… just one oligodendrocyte can myelinate PORTIONS of MULTIPLE axons

Function of Schwann cells

glial cells in peripheral nerv system that produce myelin for axons in periph nerv system… wraps around ONE SEGEMENT of ONE axon

Function of mitochondria

produce usable cellular energy in the form of ATP

How are proteins synthesized in the cell body?

in DNA in the nucleus lies genetic instructions that direct protein synthesis (which takes place in the ribosomes)… ribosomes translate this info from DNA into amino acid chains that fold into proteins

Difference between transcription and translation

copying dna into rna by enzyme rna polymerase vs copying rna into proteins

Function of sensory receptors, and what electrical change occurs there

they convert different forms of energy (light, sound, pressure, temp, chemical molecules) into biological signals the nervous system can process… sensory transduction

Input, integration, conduction, and output zone of a neuron

dendrites input, soma integrate, axon conduce, axon terminals output

Function of blood-brain barrier

they protect the brain from toxins, pathogens, and certain neurotransmitters by being selectively permeable (lipid solubles cross easily, water solubles do not!!!!!!!)

What are the relative concentrations of the ions Na+, K+, and Cl- during RESTING POTENTIAL inside and outside the membrane?

inside high K+ (potassium) concentration, outside high Na+ (sodium) and Cl- (chloride)

Directions of the electrostatic force and force of diffusion on each ion when the neuron is RESTING

come back tbh

At RESTING POTENTIAL which ion channels are all open, mostly closed, or some open some closed?

Cl- all open, Na+ mostly closed, K+ some open some closed

Why is most of the Na+ concentrated outside of axon at resting potential?

at rest, the axon membrane is more permeable to K+ because more K+ channels are open… pump moves 3 Na+ ions out of cell and two K+ in

Function of sodium-potassium active transport system in maintaining resting potential… what would happen to potential if the pump stopped working

transports ions against their gradients- three Na+ out, two K+ in… neuron would lose resting potential because passive forces constantly allow small amounts of Na+ in and K+ out, which if left alone would lead concentration differences to disappear and therefore loss of resting potential

What is a steady state, and how is it maintained during neuron’s resting state?

the ongoing balance of the interacting physiological mechanisms that keep the neuron stable… individual ions are constantly influenced by physical forces that encourage movement across membrane, and at the same time the pump and selective permeability maintain ionic gradients needed for neuron excitability

What processes are necessary for a neuron to depolarize and generate an AP?

summed excitatory input arrives and some Na+ channels begin to open… when threshold of excitation reached, voltage-gated Na+ channels rapidly open and Na+ ions rush into cell

Where does the action potential begin?

the axon hillock

What is membrane potential… how does it change at the axon hillock when threshold of excitation is reached?

the difference in electrical charge between the interior and exterior of a biological cell… rapidly changes as Na+ rushes in and causes depolarization

What is the order over time in which voltage-gated ion Na+ and K+ channels open and close during an action potential?

Na+ open first, then K+ channels open more slowly, then Na+ close, then K+ close

How does saltatory conduction operate in the spread of the action potential?

it allows action potentials to be regenerated ONLY at the nodes of renvier, which increases conduction velocity while reducing the metabolic energy needed to restore ionic gradients

Why is the rate of the AP higher along a myelinated axon compared to an unmyelinated axon?

myelin acts as an electrical insulator, greatly increasing the speed at which APs travel

What is the absolute refractory period… when during AP does it occur?

many Na+ channels are already open or inactive, so a second AP cannot begin… when threshold is reached and the action potential begins

What is decremental conduction… what type of axons do we use to measure decremental conduction?

the local electrical current gradually decreases in magnitude as it travels beneath myelin sheath to next node of ranvier… large, myelinated motor (efferent) axons

What is hyperpolarization… what processes are necessary for a neuron to hyperpolarize?

the membrane potential becomes temporarily more negative than the resting membrane potential- it decreases the likelihood of another AP… an efflux (outward flowing) of K+ or influx of Cl-

What happens with K+ channels that brings about hyperpolarization?

some K+ channels remain open, so K+ continues to leave the axon, which can cause the membrane to become temporarily more negative than resting state and produce hyperpolarization

What processes are required for repolarization and a return to resting?

near the peak, Na+ channel inactivation overlaps with K+ channels opening and K+ begin to slowly exit, which ends the rising phase and brings neuron back to resting

What is relative refractory period… at what point during AP does it occur?

a new AP can be generated only if a stronger-than-normal stimulus is applied… occurs after absolute refractory period, when some Na+ channels have recovered from inactivation

What opens ion channels in the axon… what opens ion channels in postsynaptic membrane?

a signal from another neuron changes membrane voltage and open voltage-gated channels… calcium channels in presynaptic terminal open, which causes a neurotransmitter to release and bind to proteins in postsynaptic membrane and change its shape to let in specific ions

Where are postsynaptic ion channels located?

dendrites, dendritic spines, soma

Differences between action potential and postsynaptic (graded) potentials

action potentials rise slowly until threshold of excitation, then continue rising rapidly, then fall down below threshold, repeat… graded potentials can rise AND FALL below the threshold multiple times before reaching it and rising quickly, then falling below again and repeat

Difference between EPSP (excitatory) and IPSP (inhibitory)

make postsynaptic membrane more positive (depolarized) and increase probability of generating AP… make postsynaptic membrane more negative (hyperpolarized) and decrease probability of generating AP

What are spatial/temporal summation and what are their differences?

mechanisms by which neurons integrate excitatory synaptic inputs before generating AP… allows nervous system to integrate info arriving at the same time from DIFFERENT presynaptic neuron locations vs EPSPs arriving in rapid succession from SAME synapse

What is the process that occurs to reduce the release of a neurotransmitter during presynaptic inhibition?

inhibitory neurotransmitter GABA decreases Ca²+ entry into presynaptic terminal… one neuron decreases amount of neurotransmitter released from another’s axon terminal before it reaches postsynaptic neuron

What are autoreceptors’ function… where are they found

bind a neuron’s own neurotransmitters and reduce further neurotransmitter release through negative feedback… on axon terminal

Differences in ionotropic and metabotropic receptors

neurotransmitter binding site and ion channel are part of same protein complex, and binding directly opens ion channels… ion channels open indirectly through intracellular signaling pathways (slower but more flexible)

What ion channels are found in postsynaptic membrane

Na+ (opening enters Na+ and produces EPSP), K+ (opening exits K+ and produces IPSP), Cl- (opening enters Cl- and produces IPSP)

When a neurotransmitter binds to a post-synaptic receptor and directly opens a Na+, K+ or Cl- ion channel, what are the electrical consequences in the cell body during each of these cases?

Na+ enters cell, membrane depolarized bc of influx of positive charge, EPSP, higher likelihood of AP… K+ leaves cell, membrane hyperpolarized bc of less positive charge, IPSP, decreased likelihood of AP… Cl- enters cell, membrane hyperpolarized bc of increased negative charge, IPSP, decreased likelihood of AP

What two sequences can indirectly open ion channels when a neurotransmitter binds to a postsynaptic receptor?

neurotransmitter binds to receptor, activates G-protein, and alpha subunit directly binds to and opens ion channel OR neurotransmitter binds to receptor, activates G-protein, and alpha subunit stimulates an enzyme which produces another messenger that opens ion channel

What does the somatic (skeletal) subset of peripheral nervous system control?

skeletal muscles- provides peripheral pathway through which central nervous system produces movements of body

What does the autonomic subset of the peripheral nervous system control… what are the functions of its two subsets (sympathetic & parasympathetic)?

smooth muscle, cardiac muscle, and glands… sympathetic coordinates widespread physiological changes that prepare organism to respond to increased demands (i.e. dilated pupils, accelerated heartbeat)… sympathetic coordinates physiological processes associated with maintenance/restoration (i.e. pupils constrict, heartbeat slows)

What are the parts of the central nervous system, and what does this system control?

brain and spinal cord… collects sensory info, processes it, and responds

What is the order of the meninges from OUTER TO INNER?

dura mater, arachnoid membrane, pia mater

Function of the frontal lobe

planning, execution/control of movement, working memory, prospective memory, extinction learning, autobiographical retrieval, self control, Broca’s area (language production)

Function of the parietal lobe

receives information associated with body and skin (somatosenses- touch, pressure, temperature, pain), primary somatosensory cortex

Function of temporal lobe

primary auditory cortex, memory processes, emotional processes, language comprehension, visual object recognition, Wernicke’s area (language comprehension)

Function of occipital lobe

visual processing- visual info from eyes projects here, but cortical processing does not end here

What is the function of the association cortices from the most proximal to the primary cortex (closest) to the most distal area of the association cortex (most distant) for each of the primary cortices?

come back….

Function of primary motor cortex

stimulation in specific area produces movement in corresponding region of body (i.e. if you don’t have many neurons in prim. motor cortex associated w/ movement in finger, won’t be able to move finger well)