Anatomy & Physiology

Anatomy & Physiology Study Guide

3.4 Chapter Three Review An introduction to cells: • Contemporary cell theory incorporates several basic concepts: (1) Cells are the building blocks of all plants and animals; (2) cells are produced by the division of preexisting cells; (3) cells are the smallest units that perform all vital physiological functions; and (4) each cell maintains homeostasis at the cellular level. • Cytology is the study of cellular structure and function. • The human body contains two types of cells: sex cells (sperm and oocytes) and somatic cells (all other cells). The plasma membrane separates the cell from its surrounding environment and performs various functions: • A typical cell is surrounded by extracellular fluid—specifically, the interstitial fluid of the tissue. The cell’s outer boundary is the plasma membrane. • The plasma membrane’s functions include physical isolation, regulation of exchange with the environment, sensitivity to the environment, and structural support. • The plasma membrane is a phospholipid bilayer that contains other lipids, proteins, and carbohydrates. Organelles within the cytoplasm perform particular functions: • The cytoskeleton gives the cytoplasm strength and flexibility. It has four components: microfilaments (typically made of actin), intermediate filaments, microtubules (made of tubulin), and thick filaments (made of myosin). • Microvilli are small projections of the plasma membrane that increase the surface area exposed to the extracellular environment. • Centrioles direct the movement of chromosomes during cell division and organize the cytoskeleton. The centrosome is the cytoplasm surrounding the centrioles. • Cilia beat rhythmically to move fluids or secretions across the cell surface. • Ribosomes, responsible for manufacturing proteins, are composed of a small and a large ribosomal subunit, both of which contain ribosomal RNA (rRNA). Free ribosomes are in the cytoplasm, and fixed ribosomes are attached to the endoplasmic reticulum. • The endoplasmic reticulum (ER) is a network of intracellular membranes that function in synthesis, storage, transport, and detoxification. • The Golgi apparatus forms secretory vesicles, develops new membrane components, and packages lysosomes. • Lysosomes are vesicles filled with digestive enzymes and are responsible for the autolysis of injured cells. • Peroxisomes carry enzymes that neutralize potentially dangerous free radicals. • Mitochondria are responsible for ATP production through aerobic metabolism.

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