Human Biology: Cell Structure, Tissues, Organs, and Energy Metabolism

Vocabulary practice flashcards covering animal cell organelles, primary tissue classifications, major organ anatomy and functions, and metabolic pathways including cellular respiration and BMR.

Cell membrane

An outer coating which selectively transports substances into and out of the cell.

Nucleus

The control center of the cell containing DNA that regulates its general and specialised activities and functions.

Ribosomes

Organelles composed of ribonucleic acid (RNA) and proteins that serve as protein factories to manufacture other proteins.

Endoplasmic reticulum (ER)

A network that manufactures, regulates, and stores materials; the rough ER produces proteins, while the smooth ER manufactures lipids and detoxifies.

Mitochondria

Organelles situated in the cytoplasm, known as the 'powerhouse', that supply the cell's energy source by producing ATP energy.

Centrioles

Organelles that replicate during cell reproduction and are essential for cell division (mitosis).

Lysosomes

Organelles containing digestive enzymes that break down waste and digest worn-out parts of the cell.

Golgi apparatus

An organelle that modifies, packages, and stores manufactured proteins and transports them out of the cell.

Cytoplasm

The jelly-like medium within the cell that holds organelles.

Mitosis

The process by which human cells reproduce as chromosomes and centrioles replicate, resulting in two identical daughter cells.

DNA

Nucleic acid that carries the cell's genes as chromosomes, functioning as loaded instructions for making cell functions.

Enzymes

Protein catalysts that enable metabolic reactions at low temperatures and are involved in all cell functions of respiration, growth, excretion, and irritability.

Connective tissue

A primary tissue type with a supportive structural role in the body that provides support, protection, insulation, and substance transport, encompassing bone, cartilage, and blood.

Loose connective tissue

Connective tissue proper containing few, loosely arranged collagen, elastin, and reticular fibres, abundant ground substance, and cells like fibroblasts, macrophages, and mast cells; functions in support, binding, defence, and nutrient exchange.

Dense connective tissue

Connective tissue proper containing densely packed collagen fibres, few cells (primarily fibroblasts), and little ground substance; provides strong support and resistance to pull.

Adipose tissue

Connective tissue composed of large fat-filled cells (adipocytes) with little ground substance and few fibres, functioning in energy storage, insulation, cushioning, and protection.

Cartilage

An avascular connective tissue with chondrocytes in lacunae and a firm, flexible matrix of collagen and proteoglycans; functions to provide support, reduce friction, and absorb shock.

Bone

A vascular connective tissue containing osteocytes in lacunae embedded in a hard matrix of collagen and calcium salts; provides support, protection, mineral storage, and blood cell production in marrow.

Fluid connective tissue

Connective tissue consisting of blood (plasma, red blood cells, white blood cells, and platelets) or lymph (mostly lymphocytes) with no fibres in fluid form, functioning in transport, immunity, and clotting.

Epithelial tissue

Thin sheets of cells that make up coverings and linings of the body, cavities, hollow organs, tubes, and endocrine glands, functioning to protect underlying structures, secrete, and absorb.

Simple squamous epithelium

A single layer of thin, flat cells with flat, oval-shaped nuclei found in alveoli, capillaries, and Bowman's capsule that allows fast diffusion and filtration.

Simple cuboidal epithelium

A single layer of cube-shaped cells with round, central nuclei found in kidney tubules, ducts of glands, and thyroid follicles that assists with absorption and secretion.

Simple columnar epithelium

A single layer of tall, column-shaped cells with oval nuclei near the base found in the stomach, small intestine, and large intestine that aids in absorption and secretion.

Ciliated epithelium

A single layer of columnar cells with cilia and oval nuclei near the base found in the trachea, bronchi, and oviducts that moves mucus or eggs along the surface.

Keratinised compound epithelium

A compound epithelial tissue, such as skin, where the outer layer consists of dead, flattened cells filled with the protein keratin, providing a waterproof outer layer.

Simple compound (stratified) epithelial tissue

Epithelial tissue with more than one layer of cells where all cells touch the basement membrane; found in areas subject to wear and tear, ducts of glands, and parts of the urinary tract.

Striated (skeletal) muscle

Voluntary muscle tissue under conscious control featuring long, cylindrical fibres with light and dark bands (striations) and many nuclei at the cell edges; functions to move bones.

Non-striated (smooth) muscle

Involuntary muscle tissue composed of spindle-shaped cells with one central nucleus and no striations; controls internal body processes such as peristalsis in the digestive system.

Cardiac muscle

Involuntary striated muscle tissue found only in the heart wall, featuring short, branched fibres with one or two central nuclei; it never tires and pumps blood around the body.

Contractibility

A characteristic of muscle tissue defined as the ability to shorten and thicken.

Irritability

The characteristic of muscle tissue defined as the ability to respond to stimuli created by nervous impulses.

Extensibility

A characteristic of muscle tissue defined as the ability to stretch.

Elasticity

A characteristic of muscle tissue defined as the ability to return to its original shape following contraction.

Neurone

A specialised, excitable nerve cell consisting of a cell body, axon, and dendrites that receives stimuli, converts it into a nerve impulse, and transmits it to other neurons, muscles, and glands.

Neuroglia

Non-excitable glial cells that support and protect neurons, being smaller and more numerous than neurons and forming over $50\%$ of brain tissue.

Brain

The nervous center located in the skull that controls all life functions.

Heart

An organ situated in the central chest area that circulates blood to all tissues, essential for life.

Lungs

Two organs located on either side of the heart that facilitate the exchange of gases during respiration.

Testes

Male sexual organs situated in the groin that secrete testosterone and produce sperm.

Liver

A major digestive organ situated in the upper right of the abdomen, involved in digestion and the excretion of waste products.

Pancreas

An organ located behind the stomach that secretes vital digestive enzymes.

Small intestine

Digestive organ comprising the duodenum and ileum, where the main food absorption takes place.

Large intestine

Digestive organ comprising the cecum and colon, where water absorption takes place.

Kidneys

Two organs located on either side of the body, above and slightly behind the large intestine, that secrete urine to be stored in the bladder.

Metabolism

The total of all chemical reactions that occur in the body, converting digested food into substances and energy needed for growth and normal body functions.

Catabolism

The metabolic process of breaking down complex substances into simpler substances, releasing energy for the body to use.

Anabolism

The metabolic process that builds complex substances from simpler substances, requiring energy.

Aerobic respiration

A form of cellular respiration taking place in the mitochondria that uses oxygen to release energy, producing carbon dioxide and water.

Anaerobic respiration

A form of cellular respiration taking place in the cytoplasm when there is insufficient oxygen, producing lactic acid in human cells.

Basal metabolic rate (BMR)

The minimum amount of energy the body needs at rest to maintain essential functions, supporting breathing, circulation, and vital organ function.