Essentials of Human Anatomy & Physiology: Chapter 3 - Cells and Tissues Study Notes

Cells

The structural and functional units of all living things.

Cell Theory

The fundamental principle stating that cells are the basic structural and functional units of life, an organism's activity depends on its collective cellular activities, structure dictates function, and life has a cellular basis.

Principle of Complementarity

The concept that the biochemical activities of cells are dictated by their structural forms (anatomy), which determine their specific functions (physiology).

Plasma Membrane

The flexible outer limit of the cell that acts as a selectively permeable barrier.

Nucleus

The membrane-bound central control center of the cell containing genetic material ($DNA$).

Cytoplasm

The cellular content located between the plasma membrane and the nucleus, consisting of cytosol, inclusions, and organelles.

Mitochondria

Double-membrane organelle known as the "powerhouse" of the cell that performs aerobic cellular respiration to synthesize adenosine triphosphate ($ATP$).

Ribosomes

Structures composed of ribosomal $RNA$ ($rRNA$) and protein that serve as the primary sites of protein synthesis.

Rough Endoplasmic Reticulum

Membranous network studded with ribosomes that synthesizes and packages proteins for cell membranes, lysosomes, or export.

Smooth Endoplasmic Reticulum

Membranous network lacking ribosomes that functions in lipid and steroid synthesis, lipid metabolism, and drug detoxification.

Golgi Apparatus

A stack of flattened membranous sacs that modifies, packages, and routes proteins received from the rough ER.

Lysosomes

Membranous bags containing digestive enzymes used to break down worn-out cell parts, debris, and foreign pathogens.

Diffusion

Passive movement of solutes from an area of higher concentration to lower concentration down a concentration gradient.

Osmosis

The simple diffusion of water molecules across a selectively permeable membrane through protein channels called aquaporins.

Isotonic Solution

A solution with identical solute and water concentrations as the cell cytoplasm, resulting in no net water movement.

Hypertonic Solution

A solution with a higher solute concentration than the cell, drawing water out and causing the cell to shrink (crenate).

Hypotonic Solution

A solution with a lower solute concentration than the cell, causing water to rush in and making the cell swell or burst (lyse).

Sodium-Potassium Pump ($Na^+-K^+$ Pump)

An active transport mechanism that uses $ATP$ to move three sodium ions ($Na^+$) out of the cell and two potassium ions ($K^+$) into the cell against concentration gradients.

Mitosis

The division of the cell nucleus resulting in two genetically identical daughter nuclei, composed of prophase, metaphase, anaphase, and telophase.

Cytokinesis

The division of the cytoplasm that begins in late anaphase and completes during telophase to form two distinct daughter cells.