Physiology, Metabolism, and Molecular Interactions Flashcards

Flashcards covering key terminology across homeostasis, cell transport systems, cellular respiration and metabolism, and molecular chemistry.

Homeostasis

The state of steady internal conditions and the body's intrinsic ability to maintain a dynamic consistency of internal conditions despite changes in the external environment.

Set Point

The targeted value for a given control variable that the body continuously attempts to maintain to achieve homeostasis, such as $98.6\,^{\circ}\text{F}$ for body temperature.

Antagonistic Effectors

Effectors that work in opposition to each other to regulate body conditions, such as the sympathetic and parasympathetic nervous systems.

Positive Feedback

A regulatory mechanism that amplifies changes and pushes the body further out of homeostasis, such as uterus growth during pregnancy or the activation of blood clotting factors.

Passive Transport

A transport process across a biological membrane that requires no energy because solutes move down their concentration gradient from high to low solute concentration.

Ligand-Gated Channel

A gated membrane protein channel that requires a specific molecule or ligand to bind to its receptor in order for the channel gate to open for ion transport.

Voltage-Gated Channel

A gated membrane protein channel that opens to transport ions only when the electrical membrane potential reaches a specific threshold value.

Primary Active Transport

An active transport process that directly utilizes energy from ATP to move solutes across a membrane against their concentration gradient from low to high concentration.

Secondary Active Transport

An active transport process where one molecule moves down its concentration gradient to harvest energy, which is then used to transport a second molecule against its concentration gradient.

Symport

A membrane transport process in which two different types of solutes are transported across the membrane simultaneously in the same direction.

Intracellular Fluid

The fluid residing inside cells, which makes up $67\%$ of total body water and contains a high concentration of potassium ions.

Interstitial Fluid

The extracellular fluid surrounding and located between cells, comprising $80\%$ of total extracellular fluid.

Catabolism

The metabolic branch consisting of chemical reactions that break down complex macromolecules into simpler monomers, releasing energy in the process.

Activation Energy

The minimum amount of energy required to initiate a chemical reaction, which enzymes function to decrease.

Zymogen

An inactive form of an enzyme that requires structural modification or activation, such as cleavage of peptide fragments, before it can become functionally active.

Competitive Inhibitor

A protein modulator that directly blocks ligand binding at the active site of a protein, an effect that can be overcome by increasing substrate concentration.

Glycolysis

An anaerobic metabolic pathway occurring in the cytoplasm that breaks down 1 molecule of glucose into 2 molecules of pyruvate, yielding a net total of $2\,\text{ATP}$ and $2\,NADH + H^+$.

Electron Transport Chain

A metabolic process located on the inner mitochondrial membrane where indirect energy from $NADH + H^+$ and $FADH_2$ is converted into direct ATP energy via electron jumping.

Gluconeogenesis

The metabolic pathway responsible for producing new glucose from non-carbohydrate sources, such as fats and amino acids.

Beta Oxidation

The metabolic pathway that breaks down fatty acids into acetyl-CoA, producing ketone bodies as a byproduct.

Octet Rule

The fundamental chemical principle stating that an atom's outermost electron orbital requires 8 electrons to be complete and fully stable.

Buffer

A chemical substance or system that minimizes changes in the pH of a solution when an acid or a base is added to it.

Carbonic Acid-Bicarbonate System

The primary physiological buffer system in the human body governed by the equilibrium reaction $CO_2 + H_2O \rightleftharpoons H_2CO_3 \rightleftharpoons H^+ + HCO_3^-$.

Glycogen

A complex carbohydrate polysaccharide composed of thousands of linked glucose units, stored primarily in the liver and muscles for future energy use.

Homocysteine

A non-protein amino acid whose elevated levels in the human body are associated with increased risks of cardiovascular disease.

Protein Denaturation

The permanent structural disruption of a protein back to its primary structure caused by extreme changes in pH or temperature, leading to a loss of biological function.

Antiparallel Strands

The structural arrangement of the two complementary strands of a DNA double helix, where one strand runs in the $5'\text{--}3'$ direction and the other in the $3'\text{--}5'$ direction.