Cells, Tissues, and Human Organization Flashcards

Comprehensive vocabulary flashcards covering cell structure and organelles, tissue classification and characteristics, human body cavities, and homeostatic feedback mechanisms.

Cell Theory

The fundamental biological principle stating that all organisms are composed of one or more cells, cells are the basic living unit of structure and function in organisms, and all cells come only from pre-existing cells.

Prokaryotic Cell

A category of cells that lacks a membrane-bound nucleus and contains a single chromosome consisting of a loop of DNA; includes Bacteria and Archaea.

Eukaryotic Cell

A category of cells containing a membrane-bounded nucleus that keeps DNA separate from the rest of the cell; includes plants, animals, fungi, and human cells.

Plasma Membrane

A selectively permeable boundary that controls the movement of substances into and out of the cell.

Cytoskeleton

An internal cell structure composed of actin filaments, intermediate filaments, and microtubules that supports the cell and plays a key role in cell division and molecular transport.

Cytoplasm

The semi-fluid 'jelly' filling the interior of the cell that contains proteins and other cellular materials.

Centriole

A cellular organelle composed of microtubules that is critical for the development of the mitotic spindle during cell division.

Peroxisome

An organelle containing digestive enzymes that utilize oxygen, generating hydrogen peroxide as a byproduct which is subsequently broken down into water and oxygen.

Rough ER

Endoplasmic reticulum studded with ribosomes on its surface, responsible for the processing and modification of proteins.

Ribosomes

Cellular structures that read genetic code to manufacture proteins.

Lysosome

An organelle functioning as the cell's 'garbage truck' that uses hydrolytic digestive enzymes operating in conditions of low oxygen and low pH.

Golgi Apparatus

An organelle functioning as the cell's 'post office' that collects, sorts, and packages proteins and lipids.

Smooth ER

Endoplasmic reticulum involved in the processing and synthesizing of lipids, such as steroids and hormones.

Nucleus

The information centre of the cell that houses DNA formatted as chromosomes.

Nuclear Envelope

The double membrane that encloses and surrounds the cell nucleus.

Nuclear Pore

An opening in the nuclear envelope that allows RNA and other essential molecules to pass through.

Nucleolus

A region inside the nucleus responsible for building RNA molecules necessary for protein synthesis.

Vesicle

A small, membrane-bound 'bubble' within the cytoplasm that transports molecules.

Chloroplast

An organelle found in plant cells that performs photosynthesis to produce sugar and oxygen.

Vacuole

A large storage vesicle prominent in plant cells that holds water, sugars, toxins, and other materials.

Mitochondria

The powerhouses of the cell responsible for generating ATP, the cellular energy molecule.

Epithelial Tissue

A type of tissue consisting of tightly connected cells forming continuous layers or sheets, often featuring two distinct surfaces exposed to different environments.

Squamous Epithelial Cells

Flattened epithelial cells containing a small, centrally located nucleus.

Cuboidal Epithelial Cells

Epithelial cells that are cube-shaped.

Columnar Epithelial Cells

Epithelial cells that resemble rectangular pillars or columns.

Simple Epithelium

A structural classification of epithelial tissue consisting of a single layer of cells.

Stratified Epithelium

A structural classification of epithelial tissue composed of two or more layers of cells.

Pseudostratified Epithelium

A classification of epithelial tissue that appears to have multiple layers but actually consists of only a single layer of cells.

Epithelial Membrane

A composite structure consisting of an exposed epithelial layer joined to underlying connective tissue by a non-cellular basement membrane.

Mucous Membrane

A type of epithelial membrane lining body cavities that open to the outside, providing protection, absorption, and secretion.

Serous Membrane

A membrane lining closed body cavities and covering organs within them (e.g., pericardium around the heart), composed of simple squamous epithelium that secretes lubricating serous fluid.

Connective Tissue

The most abundant and widely distributed tissue type in the body that supports and binds body parts, consisting of cells, fibres (elastic or collagen), and a non-cellular matrix.

Areolar Connective Tissue

A type of loose connective tissue proper with large spaces between fibres that acts as soft packing material around organs.

Dense Regular Connective Tissue

A tissue proper with a high density of collagen fibres arranged parallel to each other, forming structures like tendons and ligaments.

Dense Irregular Connective Tissue

A tissue proper with fibres overlapping in many directions, located in the deep layer of skin (dermis).

Fibrous Cartilage

A tough type of supportive cartilage that is resistant to stretching, located in intervertebral discs and knees.

Hyaline Cartilage

The most abundant type of cartilage in the body, found covering the ends of bones at joints.

Elastic Cartilage

A flexible type of supportive cartilage located in the ears and epiglottis.

Bone

A specialized supportive connective tissue that provides bodily structure and protection.

Adipose Tissue

A specialized connective tissue (fat) responsible for protection and thermal regulation.

Blood

A specialized fluid connective tissue functioning in transport of nutrients and gases, immune defense via white blood cells, and healing via platelets.

Lymph

A specialized fluid connective tissue that manages excess fluid, works with the immune system, and carries white blood cells, proteins, and fats.

Synovial Membrane

A connective tissue membrane lining freely movable joints with two layers: an inner layer that secretes synovial fluid to prevent bone friction, and a protective outer layer.

Meninges

A three-layered connective tissue membrane (dura, arachnoid, and pia mater) covering and anchoring the brain and spinal cord, functioning as a shock absorber.

Skeletal Muscle Tissue

Voluntary muscle tissue characterized by striated, organized parallel fibers that move bones and generate heat.

Smooth Muscle Tissue

Involuntary muscle tissue composed of unstriated, spindle-shaped cells located in blood vessels, the digestive system, and the reproductive system.

Cardiac Muscle Tissue

Involuntary, striated, and branched muscle tissue found exclusively in the heart.

Nervous Tissue

Tissue composed of specialized cells called neurons that receive stimuli and generate or conduct nerve impulses.

Cranial Cavity

A sub-cavity within the dorsal body cavity that contains the brain.

Spinal Cavity

A sub-cavity within the dorsal body cavity that contains the spinal cord.

Thoracic Cavity

A sub-cavity within the ventral body cavity located superior to the diaphragm that contains the heart and lungs.

Abdominopelvic Cavity

A ventral body cavity divided into the abdominal cavity (containing digestive organs) and the pelvic cavity (containing urinary and reproductive organs).

Homeostasis

The state of relative internal stability or dynamic equilibrium maintained by animal bodies around a set value, such as maintaining blood $\text{pH} = 7.4$.

Positive Feedback Loop

A feedback mechanism in which a change continues in the same direction, continuously increasing or intensifying the original stimulus.

Negative Feedback Loop

A homeostatic control mechanism that changes the direction of a stimulus to counteract a change and restore baseline balance (e.g., cooling the body down when overheated).