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Cell Theory

All living organisms are made up of cells.

Cell Membrane

Controls entry and exit of substances, selectively permeable, made of phospholipid bilayer.

Selective Permeability

The ability of the cell membrane to allow certain molecules to pass through while blocking others.

Passive Transport

Movement of molecules across the membrane without energy input from the cell.

Diffusion

Movement of molecules from an area of higher concentration to an area of lower concentration.

Osmosis

Movement of water across a semi-permeable membrane from an area of higher water concentration to lower water concentration.

Active Transport

Movement of molecules against their concentration gradient using energy (ATP).

Mitochondria

Site of cellular respiration; produces ATP.

Glycolysis

The first step of cellular respiration occurring in the cytoplasm where glucose is broken down into pyruvate.

Ribosomes

Sites of protein synthesis, made of rRNA and proteins.

Epithelial Tissue

Covers surfaces of the body; functions include protection, secretion, and absorption.

Connective Tissue

Supports, binds together, and protects tissues; includes bone, cartilage, and blood.

Muscle Tissue

A type of tissue that contracts to cause movement; includes skeletal, cardiac, and smooth muscle.

Metabolism

The sum of all chemical reactions in the body.

Anabolic Reactions

Reactions that build complex molecules from simpler ones, requiring energy.

Catabolic Reactions

Reactions that break down complex molecules into simpler ones, releasing energy.

Enzymes

Biological catalysts that speed up chemical reactions by lowering activation energy.

Skeletal Muscle

Voluntary muscle responsible for body movements.

Cardiac Muscle

Involuntary muscle found in the heart; responsible for pumping blood.

Autonomic Nervous System

Part of the nervous system that controls involuntary bodily functions.

Blood Plasma

The liquid component of blood that transports cells, nutrients, and hormones.

Red Blood Cells (RBCs)

Cells that carry oxygen from the lungs to the rest of the body.

White Blood Cells (WBCs)

Cells that are part of the immune system and help fight infections.

Platelets

Cell fragments involved in blood clotting.

Nephron

The functional unit of the kidney responsible for filtration and urine formation.

Osteoporosis

A condition characterized by decreased bone density, leading to increased fragility.

Osteoarthritis

Degeneration of cartilage in joints, causing pain and stiffness.

Compact Bone

The dense outer layer of bone tissue.

Spongy Bone

Bone tissue that contains trabeculae and bone marrow; less dense than compact bone.

Diaphysis

The shaft or central part of a long bone.

Epiphysis

The end part of a long bone, initially growing separately from the shaft.

Periosteum

A dense layer of vascular connective tissue surrounding the bones except at the surfaces of the joints.

Homeostasis

The maintenance of a stable internal environment within an organism.

Scientific Method

A systematic approach to investigating phenomena, including formulating hypotheses and testing them.