Introductory Human Physiology – Solutions, pH, Buffers & Biomolecules

Vocabulary flashcards covering key terms from the lecture on aqueous solutions, pH regulation, buffering, and fundamental biomolecules and their synthesis.

Aqueous Solution

A solution in which water acts as the solvent for all dissolved or suspended substances found inside and outside cells.

Polarity (of Water)

The unequal distribution of electrical charge in a water molecule that enables formation of hydration (solubility) spheres around solutes.

Hydration / Solubility Sphere

Layers of oriented water molecules that surround charged or polar solutes, keeping them in suspension within an aqueous solution.

Suspension (in physiology)

The state in which particles are kept dispersed and floating in a fluid because they are surrounded by hydration spheres.

Protein Surface Charge

Most proteins carry an overall negative charge, allowing water to form hydration spheres that keep them soluble.

pH (Physiology Definition)

A measure of proton (H⁺) concentration in an aqueous solution; equals the negative logarithm of the ratio of protons to water molecules.

Proton (in pH context)

A hydrogen atom that has lost its electron (H⁺); the particle whose concentration determines pH in physiology.

Physiologic Blood pH

The tightly regulated pH range of human blood: 7.35 – 7.45 (slightly alkaline).

Buffer

A substance that can accept or donate protons, resisting changes in pH of a biological fluid.

Amino Acid

The building block of proteins, composed of a central carbon bonded to an amino group, carboxyl group, hydrogen, and variable R-group; functions as a buffer.

Carboxyl Group (-COOH)

The acidic functional group of an amino acid that can donate a proton, contributing to buffering capacity.

Amino Group (-NH₂)

The basic functional group of an amino acid that can accept a proton, also contributing to buffering capacity.

Variable (R) Group

The side chain attached to the central carbon of an amino acid that determines which of the 20 amino acids it is.

Triglyceride

A lipid formed by three fatty acids ester-linked to a glycerol (carbohydrate) backbone.

Fatty Acid

A long hydrocarbon chain with a terminal carboxyl group; major component of many lipids.

Glycerol

A three-carbon sugar alcohol that serves as the backbone for triglycerides.

Steroid

A lipid category consisting of four fused hydrocarbon rings; derived from cholesterol.

Cholesterol

A sterol lipid that forms the core structure of steroids and modulates membrane fluidity.

Phospholipid

A lipid containing a phosphate group; major structural component of cell membranes.

Glycolipid

A lipid with attached carbohydrate chains that contribute to cell recognition and signaling.

Glycocalyx

The carbohydrate-rich external coat formed by glycolipids and glycoproteins on a cell’s plasma membrane, essential for cell-cell communication.

Carbohydrate (chemical ratio)

An organic molecule in which C:H:O occur in a 1:2:1 ratio, making it highly oxygenated.

Lipid (general)

A mostly carbon- and hydrogen-based macromolecule that is hydrophobic and includes fats, phospholipids, and steroids.

Protein (biosynthesis)

A macromolecule made of amino acids whose sequence is encoded by DNA and produced through transcription and translation.

Transcription

The cellular process that copies DNA information into complementary RNA molecules.

Translation

The process at ribosomes where the nucleotide sequence of mRNA is converted into a specific amino-acid sequence of a protein.

Messenger RNA (mRNA)

The RNA copy of a gene that carries coding information from DNA to ribosomes for protein synthesis.

Transfer RNA (tRNA)

An RNA molecule that delivers specific amino acids to the ribosome during translation.

Ribosomal RNA (rRNA)

RNA that, together with proteins, forms ribosomes – the sites of protein synthesis.

Ribosome

A cellular organelle composed of rRNA and proteins that facilitates translation of mRNA into polypeptide chains.

Enzyme

A protein catalyst that accelerates biochemical reactions and regulates cellular processes.