Human Phys Exam 1

HumanPhysExam1StudyGuideSp2026 and PCB4701_Practice_Exam_1_Fa24

Diffusion

Movement of particles from high concentration → low concentration

Osmosis

Movement of water across a selectively permeable membrane

Simple diffusion

Movement directly through the lipid bilayer without a transport protein

Facilitated diffusion

Passive movement through a membrane protein down a concentration/electrochemical gradient

Carrier protein

Membrane protein that binds a substance and changes shape to move it across

Ion channel

Membrane protein that forms a passageway for ions

Passive transport

Movement down a concentration/electrochemical gradient without directly using ATP

Active transport

Movement against a concentration/electrochemical gradient requiring energy

Primary active transport

Transport that directly uses ATP

Secondary active transport

Transport that uses the energy from another substance moving down its gradient

Coupled transport

Transport where two substances move together

Symport

Transport where two substances move in the same direction

Antiport

Transport where two substances move in opposite directions

Carrier-mediated transport

Transport that can become saturated because there are a limited number of proteins

Isotonic

Solution that causes no net water movement into or out of a cell

Hypotonic

Solution that causes water to enter a cell

Hypertonic

Solution that causes water to leave a cell

Molarity

Concentration measured in moles of compound per liter

Osmolarity

Concentration measured in total particles per liter

Na+-glucose cotransport

Movement of glucose against its gradient using Na+ movement down its gradient

Membrane potential

Voltage difference across a cell membrane

Resting membrane potential

Membrane voltage when a neuron is not generating an action potential

Equilibrium potential

Voltage at which electrical force exactly opposes chemical driving force for one ion

Chemical driving force

Force caused by a concentration difference

Electrical driving force

Force caused by attraction/repulsion of electrical charges

Electrochemical gradient

Combined chemical + electrical forces acting on an ion

Nernst equation

Equation used to calculate the equilibrium potential of one ion

K+

Ion with the greatest influence on resting membrane potential because the membrane is most permeable to it

Na+/K+ ATPase

Pump that maintains Na+ and K+ concentration gradients

Action potential

Rapid, temporary change in membrane potential that travels along an axon

Threshold

Membrane voltage that must be reached to trigger an action potential

Depolarization

Membrane becomes more positive

Repolarization

Membrane returns toward its negative resting value

Hyperpolarization

Membrane becomes more negative than resting potential

Voltage-gated channels

Channels that respond to changes in membrane voltage

EPSP

Excitatory postsynaptic potential

IPSP

Inhibitory postsynaptic potential

Neurotransmitter

Chemical messenger released by a neuron

Agonist

Substance that mimics or activates the effect of a neurotransmitter

Antagonist

Substance that blocks or reduces the effect of a neurotransmitter

Acetylcholine / ACh

Primary neurotransmitter at the neuromuscular junction

Glutamate

Major excitatory neurotransmitter

GABA

Major inhibitory neurotransmitter

Sarin

Inhibits acetylcholinesterase, preventing normal breakdown of ACh

Sarcomere

Basic contractile unit of skeletal muscle

Actin

Thin filament

Myosin

Thick filament

Troponin

Protein whose binding to Ca2+ initiates exposure of actin binding sites

Tropomyosin

Protein that covers myosin-binding sites on actin when muscle is relaxed

Synapse

Junction where a neuron communicates with another cell

Chemical synapse

Uses neurotransmitter release

Electrical synapse

Uses gap junctions

Presynaptic cell

Cell that releases neurotransmitter

Postsynaptic cell

Cell that receives neurotransmitter

Motor unit

One motor neuron + all muscle fibers it controls