UNE: PHSL 1010 Exam 1 Study Guide

integral proteins

Penetrate the hydrophobic interior of the lipid bilayer. Commerce via facilitated or active.

peripheral protein

A protein loosely bound to the surface of a membrane or to part of an integral protein and not embedded in the lipid bilayer.

Carbohydrate group

Linked with protein or lipids and function as adhesion.

Cholesterol

Steroid common in cell membranes, also in many hormones. Functions as support make the membrane more rigid and less soluble.

Structural protein

used for support such as connective tissue and keratin that forms hair and finger nails

enzyme (protein)

A type of protein that speeds up a chemical reaction in a living thing

receptor protein

Membrane protein with carbohydrates attached that helps cells identify "self" and plays a role in blood types, organ transplants, and germ recognition.

carrier protein

A membrane protein, specifically a transport protein, that holds onto molecules and changes their shapes in a way that shuttles them across the membrane.

adhesion proteins

membrane proteins that form junctions between adjacent cells

simple diffusion (passive transport)

Nonpolar lipid soluble substances diffuse directly through the phospholipid bilayer. (Solids Only)

facilitated diffusion

Movement of specific molecules across cell membranes through protein channels. Passive transport down the electrochemical gradient.

primary active transport

Active transport that relies directly on the hydrolysis of ATP. Goes against electrochemical gradient.

secondary active transport

Driven by ion movement down its gradient.

transport/channel proteins

allow passage of hydrophilic substances across the membrane

gated channel protein

A transport protein that opens a "gate," allowing a molecule to flow through the membrane.

Endocytosis

process by which a cell takes material into the cell by infolding of the cell membrane

protein pumps

transport proteins that require energy to do work

sodium-potassium pump

a carrier protein that uses ATP to actively transport sodium ions out of a cell and potassium ions into the cell

Ohm's Law

the current in a circuit equals the voltage difference divided by the resistance, V=IR

Conductance

the ease with which ions flow through a channel. G = conductance.

conductance of potassium

Ionic conductance of K is slower, resting membrane potential due mostly to K.

conductance of sodium

G(k) >> G(Na), AP is triggered by influx of Na into the cell.

electrical potential difference

The change in potential energy per unit charge in an electric field.

action potential

the change in electrical potential associated with the passage of an impulse along the membrane of a muscle cell or nerve cell.

capacitator

The ability to accept and pile up charge without changing voltage. The capacitance of a certain membrane is the number of ions that have to move through the membrane (pile up on the capacitor plates) to get a voltage change to occur. High capacitance means lots of charges moved per volt change.

How would capacitance be measured across a membrane?

Can use recording electrode inside the cell (-70mV) and reference electrode in the saline bath (0 mV).

resting membrane potential

An electrical potential established across the plasma membrane of all cells by the Na+/K+ ATPase and the K+ leak channels. IN most cells, the resting membrane potential is approximately -70 mV with respect to the outside of the cell.

equilbrium potential

Ions will follow to side with a lower concentration. Ex: one side is 0.1M KCL while the other side as 0.01M. We will see K move to the other side.

How are Na+ ions distributed among intracellular, extracellular, and plasma compartments?

10, 145, 140

How are K+ ions distributed among intracellular, extracellular, and plasma compartments?

160, 4, 4

How are Ca2+ ions distributed among intracellular, extracellular, and plasma compartments?

10^-4, 2, 2

depolarization

The process during the action potential when sodium is rushing into the cell causing the interior to become more positive.

Repolarization

Return of the cell to resting state, caused by reentry of potassium into the cell while sodium exits the cell.

Hyperpolarization

The movement of the membrane potential of a cell away from rest potential in a more negative direction.

graded potential

a shift in the electrical charge in a tiny area of a neuron

temporal summation

Summation by a postsynaptic cell of input (EPSPs or IPSPs) from a single source over time.

spatial summation

Integration by a postsynaptic neuron of inputs (EPSPs and IPSPs) from multiple sources.

Mechanical depolarization

Street activated depolarization (pucinian corpuscle). Stretch activated via ligand-gated channels.

electrical depolarization

aka action potential; spreads over the sarcolemma and causes the muscle fiber to contract

chemical depolarization

May occur as a result of recognition and response to chemical neurotransmitters at synapsis.

How are action potentials propagated along an axon?

The action potential generated at the axon hillock propagates as a wave along the axon. The currents flowing inwards at a point on the axon during an action potential spread out along the axon, and depolarize the adjacent sections of its membrane.

How are potentials measured in excitable tissues?

They are due to changes in the conduction of ions across the cell membrane. The electrical events in neurons are rapid, being measured in milliseconds (ms); and the potential changes are small, being measured in millivolts (mV).

sensory neurons (afferent)

neurons that carry incoming information from the sensory receptors to the brain and spinal cord

motor neurons (efferent)

neurons that carry outgoing information from the brain and spinal cord to the muscles and glands

Organization of the Nervous System

central nervous system and peripheral nervous system

Neurons

excitable tissue; generates and conducts electrical signals

glial cells

Support; nutrition; insulation; coordination of synaptic networks

myelinization

a process in neuronal development in which sheaths made of a substance called myelin gradually cover individual axons and electrically insulate them from one another to improve the conductivity of the nerve

saltatory conduction

Rapid transmission of a nerve impulse along an axon, resulting from the action potential jumping from one node of Ranvier to another, skipping the myelin-sheathed regions of membrane.

synaptic transmission

the process through which neurotransmitters are released by one neuron, cross the synaptic gap, and affect adjoining neurons

electrical synaptic transmission

neurons are connected via gap junctions, passive spread of depolarization, transmission of signal is immediate

chemical synaptic transmission

1.) Action potential depolarizes presynaptic terminal.

2.) Depolarization activates voltage-gated CALCIUM channels.

3.) Calcium concentration is increased in presynaptic terminal, triggers exocytosis and neurotransmitter release.

4.) Neurotransmitter diffuses across synaptic cleft, binds to neurotransmitter receptors.

5.) Neurotransmitter-receptor binding initiates postsynaptic response.

Neurotransmitters

chemical messengers that cross the synaptic gaps between neurons

neurotransmitter release

• prior to release, neurotransmitter molecules are stored in membrane-bound vesicles in nerve terminal

-when AP reaches nerve terminal, voltage gated calcium channels open allowing calcium to flow into cell

-sudden increase in Ca triggers fusion of vesicles w/ the membrane at the synapse causing exocytosis of the neurotransmitter

-once released into synapse, NT molecules diffuse across the cleft and bind to receptors on post-synaptic membrane

neurotransmitter receptors

proteins in the membranes of neurons that bind to neurotransmitters

inactivation of neurotransmitters

reuptake into presynaptic or glial cells, enzymatic breakdown in cleft & recycling, diffusion and breakdown elsewhere

graded potentials

incoming signals operating over short distances. Short, local, decremental.

Transduction in Mechanoreceptors

The four major types of tactile mechanoreceptors include: Merkel's disks, Meissner's corpuscles, Ruffini endings, and Pacinian corpuscles. Merkel's disk are slow-adapting, unencapsulated nerve endings that respond to light touch; they are present in the upper layers of skin that has hair or is glabrous.

Transduction - Chemoreceptors

peripheral chemoreceptors help maintain homeostasis in the cardiorespiratory system by monitoring concentrations of blood borne chemicals.

transduction in thermoreceptor

Thermoreceptors have been classically described as having 'free' non-specialized endings; the mechanism of activation in response to temperature changes is not completely understood.

free nerve endings

respond to pain and temperature and itch, located in the epidermis layer of the skin.

Pacinian corpuscles

respond to deep pressure and vibration, in the dermis layer

sympathetic nervous system

the division of the autonomic nervous system that arouses the body, mobilizing its energy in stressful situations, thoracic and lumbar

parasympathetic nervous system

the division of the autonomic nervous system that calms the body, conserving its energy, canal and sacral

Astrocytes (CNS)

Regulate transmission at many chemical synapses

Sacromere

Basic contracting unit of muscle cell consits of actin and myosin filaments between z-lines in a muscle cell

Actin

A globular protein that links into chains, two of which twist helically about each other, forming microfilaments in muscle and other contractile elements in cells.

muscarinic receptors

Cholinergic receptors that are located postsynaptically in the effector organs such as smooth muscle, cardiac muscle, and glands supplied by parasympathetic fibers. Are normally activated by acetylcholine.

nicotinic receptors

On all ANS postganglionic neurons, in the adrenal medulla, and at neuromuscular junctions of skeletal muscle

Excitatory when ACh binding occurs. Open chemically-gated sodium ion channels.