Unit 1: Signals and Responses

These flashcards cover key vocabulary and concepts from Unit 1: Signals and Responses, focusing on physiological principles involved in signaling and neural pathways.

Passive Transport

The movement of substances across a cell membrane without the need for energy input.

Simple Diffusion

Movement of small, nonpolar, and noncharged molecules through the phospholipid bilayer, down their concentration gradient.

Facilitated Diffusion

Movement of larger or polar molecules down their concentration gradient with the assistance of membrane proteins.

Channel Proteins

Proteins that form continuous hydrophilic pores to allow specific ions to move across a membrane.

Carrier Proteins

Proteins that bind solutes on one side of a membrane and undergo conformational changes to transport them across.

Fick’s Law of Diffusion

A law that states the rate of diffusion is proportional to the concentration gradient and surface area, and inversely proportional to the thickness of the membrane.

Homeostasis

A dynamic state of equilibrium in the body, maintaining optimal conditions for cellular function.

Negative Feedback

A regulatory mechanism in which a system responds to a change by initiating actions that counteract that change.

Positive Feedback

A process that enhances or accelerates a change, leading to an even greater response.

Equilibrium Potential

The voltage at which there is no net movement of the ion across the membrane due to balanced electrical and chemical forces.

Electrochemical Gradient

The combined effect of an ion's concentration gradient and the membrane's electrical charge determining the direction of ion movement.

Membrane Potential

The overall voltage difference across a cell membrane caused by uneven ion distribution.

Resting Membrane Potential

The electrical potential difference across a cell membrane at rest, typically around -70 mV.

Depolarization

A decrease in the membrane potential, making the inside of the cell less negative.

Repolarization

The process of returning the membrane potential back toward the resting potential after depolarization.

Hyperpolarization

An increase in the membrane potential, making the inside of the cell more negative than resting potential.

Action Potential

A rapid rise and fall in membrane potential, generating electrical impulses in neurons.

EPSP (Excitatory Postsynaptic Potential)

A change in membrane potential that makes a neuron more likely to fire an action potential.

IPSP (Inhibitory Postsynaptic Potential)

A change in membrane potential that makes a neuron less likely to fire an action potential.

Absolute Refractory Period

The period during which a second action potential cannot be initiated, regardless of stimulus strength.

Relative Refractory Period

The period following an action potential when a stronger-than-normal stimulus is required to elicit an action potential.

Graded Potentials

Small changes in membrane potential that can lead to the generation of an action potential if they reach the threshold.

Temporal Summation

The summation of graded potentials from one presynaptic neuron firing repeatedly over time.

Spatial Summation

The summation of graded potentials from multiple presynaptic neurons firing simultaneously.

Neuromodulation

The modification of how a neuron responds to neurotransmitters, affecting its excitability.

Sodium-Potassium Pump

An active transport mechanism that moves 3 sodium ions out of the cell and 2 potassium ions into the cell to maintain gradients.

Leaky Channels

Ion channels that are always open, allowing ions to passively diffuse across the membrane.

Voltage-Gated Channels

Channels that only open in response to changes in membrane potential, playing a critical role in action potential generation.

Neuromuscular Junction

A synapse between a motor neuron and a muscle cell, crucial for muscle contraction.

Pathophysiological State

Conditions resulting from malfunctioning physiological processes, leading to disease or dysfunction.