Anatomy and Physiology of Human Cells

Comprehensive vocabulary flashcards covering cell anatomy, organelles, membrane transport, cell division (mitosis), and cancer pathophysiology from the HLTAAP002 lecture notes.

Cell

The basic unit of life and the smallest part of the body capable of surviving on its own in the correct environment.

Plasma / Cell Membrane

A bi-phospholipid layer surrounding the cell that is semi-permeable (selective) and facilitates both active and passive transport.

Cell Membrane Receptors

Proteins embedded in the cell membrane that act like locks where chemicals such as drugs and hormones bind (acting as keys) to trigger a cellular response.

Tight Junctions

Impermeable, leak-proof membrane junctions that prevent fluids and molecules from leaking between cells (for example, preventing digestive enzymes in the small intestine from entering the bloodstream).

Desmosomes

Anchoring junction structures found between cells subjected to mechanical stress (such as skin cells) that prevent them from being pulled apart.

Gap Junctions

Membrane junctions that allow direct communication, electrical activity, and the passage of nutrients and ions between adjacent cells, notably seen in the heart.

Cytoplasm / Cytosol

The jelly-like fluid situated inside the plasma membrane and outside the nucleus that serves as the site for most cellular activity and suspends the organelles.

Nucleus

The control centre of the cell containing genetic material (genes) composed of Deoxyribonucleic acid ($\text{DNA}$) and enclosed by a selective, semi-permeable nuclear membrane.

Nucleoplasm

The jelly-like fluid found inside the nucleus that surrounds chromatin threads and nucleoli.

Nucleoli

Small, round bodies suspended in the nucleoplasm that serve as the assembly sites where ribosomes are manufactured.

Ribosomes

Cellular structures composed of proteins and RNA that carry out protein synthesis; they either float freely in the cytoplasm or attach to the rough endoplasmic reticulum.

Rough Endoplasmic Reticulum (rER)

A studded, ribosome-covered membrane network where newly formed proteins are processed, packaged into vesicles, and transported to the Golgi apparatus; abundant in cells that export proteins, such as the pancreas.

Messenger RNA (mRNA)

Molecules that transcribe a copy of genetic instructions from $\text{DNA}$ in the nucleus and carry it to ribosomes to direct protein synthesis.

Smooth Endoplasmic Reticulum (sER)

A tubular organelle lacking ribosomes that functions in lipid and carbohydrate metabolism, cholesterol and phospholipid production, and the detoxification of drugs.

Golgi Apparatus / Body

An organelle that modifies and packages proteins received from the rER by folding them and attaching lipids or carbohydrates before dispatching them in secretory vesicles for cellular export.

Mitochondria

Double-membraned cellular 'powerhouses' containing circular $\text{DNA}$ that use oxygen and nutrients to generate $30\text{ to }38\text{ ATP}$ per glucose molecule via aerobic respiration.

Glycolysis

An anaerobic metabolic process that breaks down glucose into pyruvic acid in the cytoplasm, yielding $2\text{ ATP}$ per glucose molecule without utilizing oxygen.

Lysosomes

Membrane-bound sacs containing powerful digestive enzymes that break down worn-out cell parts or foreign microorganisms; highly prevalent in white blood cells.

Centrioles

A pair of microtubule bundles positioned at right angles near the nucleus that form the mitotic spindle during cell division.

Cytoskeleton

An internal framework of microtubules and intermediate filaments that acts as the cell's bones and muscles, providing shape and structural support.

Cilia

Fine, hair-like cellular projections that rhythmically beat to propel substances along the cell surface, such as respiratory mucus or the ovum in fallopian tubes.

Flagella

Long, whiplike projections designed to propel an entire cell forward, found on sperm cells and certain bacteria.

Microvilli

Tiny, finger-like folds of the plasma membrane that expand surface area to enhance absorption, predominantly found on epithelial cells of the small intestine.

Intracellular Fluid (ICF)

The body fluid contained entirely within the interior of cells.

Extracellular Fluid (ECF)

All body fluids situated outside the cells, including blood plasma, lymph, and interstitial fluid.

Interstitial Fluid (IF)

The specific compartment of extracellular fluid that bathes the microscopic spaces surrounding tissue cells.

Passive Transport

The movement of substances across cell membranes down a concentration or pressure gradient without the expenditure of cellular energy.

Diffusion

Passive transport wherein molecules move from an area of higher concentration to lower concentration to achieve uniform distribution (e.g., fats, fat-soluble vitamins, $\text{O}_2$, and $\text{CO}_2$).

Simple Diffusion

The unassisted movement of lipid-soluble or small molecules directly through the phospholipid bilayer from high to low concentration.

Facilitated Diffusion

Passive movement across the membrane down a concentration gradient aided by channel or carrier proteins, utilized by larger molecules such as glucose.

Osmosis

The net diffusion of water through a semi-permeable membrane from an area of higher water concentration (lower solute) to an area of lower water concentration (higher solute).

Filtration

A passive process in which water and solutes are forced across a membrane from an area of high pressure to low pressure by fluid pressure, such as blood filtration in kidney nephrons.

Active Transport

The movement of molecules (such as amino acids, sugars, and most ions) against their concentration gradient from low to high concentration, requiring energy in the form of $\text{ATP}$.

Sodium-Potassium Pump

An active transport carrier protein driven by $\text{ATP}$ that expels $\text{Na}^+$ out of the cell and pumps $\text{K}^+$ inward to maintain electrical balance, especially in excitable nerve cells.

Exocytosis

An $\text{ATP}$-dependent active transport process in which intracellular vesicles fuse with the plasma membrane to secrete substances out of the cell.

Endocytosis

An $\text{ATP}$-dependent active transport process by which the cell engulfs extracellular materials by invaginating its plasma membrane to form vesicles.

Phagocytosis

A form of endocytosis ('cell eating') requiring $\text{ATP}$ whereby a cell surrounds, engulfs, and digests large solid particles or invading microorganisms.

Pinocytosis

A form of endocytosis ('cell drinking') requiring $\text{ATP}$ involving the non-specific uptake of extracellular droplets of fluid and dissolved solutes into tiny vesicles.

Mitosis

The division of the cell nucleus that ensures equal distribution of replicated chromosomes into two identical sets for bodily growth and repair.

Cytokinesis

The physical division of the cytoplasm into two daughter cells, which initiates during anaphase via a cleavage furrow and finishes during telophase.

Interphase

The metabolic stage of the cell cycle occupying approximately $90\%$ of the cell's lifespan, during which the cell carries out normal functions and replicates its $\text{DNA}$ in preparation for division.

Prophase

The first phase of mitosis in which chromatin condenses into distinct chromosomes, centrioles migrate to opposite poles, and the mitotic spindle forms while the nuclear membrane remains intact.

Metaphase

A brief mitotic stage during which the nuclear membrane disappears and chromosomes line up along the equatorial center of the mitotic spindle.

Anaphase

The phase of mitosis where centromeres split, sister chromatids are pulled apart as daughter chromosomes toward opposite cellular poles, and the spindle breaks.

Telophase

The final stage of mitosis during which daughter chromosomes uncoil back into diffuse chromatin, the spindle disintegrates, nuclear membranes reassemble, and a cleavage furrow deepens.

Cancer

A homeostatic imbalance where $\text{DNA}$ damage disrupts normal regulatory control mechanisms, causing uncontrolled mitosis and tumor (neoplasm) formation.

Benign Neoplasm

A slow-growing, encapsulated tumor composed of cells resembling the parent tissue; rarely fatal if excised early, with ulceration, necrosis, and systemic effects being uncommon.

Malignant Neoplasm

A fast-growing, non-encapsulated cancer that aggressively invades surrounding tissues, commonly recurs after resection, and frequently causes ulceration, necrosis, and systemic effects.

Chemotherapy

A systemic cancer treatment using chemical agents to destroy rapidly dividing cells, impacting both malignant and healthy cells and commonly producing adverse effects such as nausea, vomiting, and alopecia.

Alopecia

Loss of hair; a common side effect of chemotherapy resulting from its non-selective targeting of rapidly dividing follicle cells.