Levels of Organization

Vocabulary flashcards reviewing levels of organization in multicellular organisms, including cell differentiation, tissue types in animals and plants, organs, organ systems, and bone marrow transplants.

Unicellular Organism

An organism that is made of only one cell.

Multicellular Organism

An organism that is made of more than one cell, containing different types of cells that each perform a specific job.

Human Body Cell Count

Scientists estimate that there are $37.2 \text{ trillion}$ cells in the human body, all organized to enable the body to function.

Cell

The smallest unit of living things that carries on the functions of life and makes up all living organisms.

Cell Differentiation

The process through which unspecialized first cells divide and differentiate into specialized cell types with specific functions, such as muscle cells, nerve cells, or blood cells.

Tissue

A group of similar types of cells that work together to carry out specific tasks.

Muscle Tissue

A type of animal tissue that contracts to cause movement, posture, and heat production, categorized into cardiac, smooth, and skeletal tissue.

Connective Tissue

A type of animal tissue that provides structure, protection, support, transport, storage, and insulation, often connecting other types of tissue together (including fat, bone, blood, and cartilage).

Nervous Tissue

A type of animal tissue composed of neurons and glial cells that conducts electrical impulses, carries messages to and from the brain, and regulates body functions.

Epithelial Tissue

A type of animal tissue that forms the protective outer layer of skin and lines the interior of major organs and internal body cavities for protection, absorption, secretion, filtration, and sensation.

Four Main Types of Animal Tissue

The $4$ primary tissue classifications found in humans and most animals: muscle tissue, connective tissue, nervous tissue, and epithelial tissue.

Dermal Tissue

The outer protective tissue layer of a plant that protects the plant and helps reduce water loss.

Vascular Tissue

Plant tissue composed of tubelike cells that transports water and nutrients from one part of a plant to another.

Ground Tissue

Plant tissue where photosynthesis takes place, providing storage and support for the plant.

Three Main Types of Plant Tissue

The $3$ primary tissue classifications in plants: dermal tissue, vascular tissue, and ground tissue.

Organ

A structure made of groups of different tissues working together to perform a particular job or specific function (humans have more than $70$ organs).

Stomach

An organ specialized for breaking down food, made of all $4$ types of animal tissue: muscle tissue to contract and break up food, epithelial tissue to line the stomach, nervous tissue to signal when full, and connective tissue to support the stomach wall.

Leaf

A plant organ specialized for photosynthesis and food production, composed of dermal, ground, and vascular tissues.

Organ System

A group of different organs that work together to complete a series of tasks and functions.

Digestive System

An animal organ system comprising organs such as the stomach, small intestine, liver, and large intestine that work together to break down food and take it into the body.

Shoot System

A major plant organ system consisting of leaves, stems, flowers, fruits, and buds that functions to make and transport food and water throughout the plant.

Root System

A major plant organ system consisting of roots that anchor the plant and absorb water and nutrients from the soil.

Plant Organ Systems

The $2$ major organ systems in plants: the shoot system and the root system.

Levels of Organization

The hierarchical sequence of structure in multicellular organisms: Cell -> Tissue -> Organ -> Organ System -> Organism.

Bone Marrow

A tissue found inside some bones in the body that contains stem cells capable of developing into red blood cells, white blood cells, or platelets.

Bone Marrow Transplant

A medical procedure used when disease interferes with blood cell production, involving destroying unhealthy bone marrow and introducing healthy bone marrow harvested from a donor's pelvic bone into the patient's bloodstream.

Pointillism

A style of painting in which many tiny dots are grouped together to form an image, serving as an analogy for how individual cells group together to form tissues, organs, and organ systems.

Oxygen

A gas in air that is necessary for most plants and animals to live, transported to body tissues via the respiratory and circulatory systems.

Diffuse

To spread out or move freely through, such as water diffusing into plant roots.

Organism

A living thing, such as an animal or plant, composed of integrated organ systems working together to perform all functions necessary for survival.