Unit 3 Body Systems

Cell

The smallest living organism and the basic unit of life on earth

Tissue

A group of cells that work together to perform a specific function

Organ

A structure made up of different types of tissues that work together to perform a specific function. Examples of organs include the heart, lungs, liver, and brain.

Organ System

A group of organs that work together to perform a specific function or set of functions in the body. Examples of organ systems include the digestive system, nervous system, and circulatory system. Each organ system has a specific role in maintaining the overall health and functioning of the body.

Organism

An organism is a living individual that can carry out all the processes of life (reproduce, grow, respond to stimuli, & maintain homeostasis). It can be a single-celled organism, such as a bacterium, or a complex multicellular organism, such as a human.

Digestive System

The digestive system is responsible for breaking down food into nutrients that can be absorbed by the body. It includes organs such as the mouth, esophagus, stomach, small intestine, and large intestine. The digestive system also includes accessory organs like the liver, gallbladder, and pancreas.

Nervous System

The nervous system is responsible for coordinating and controlling the body's activities. It includes the brain, spinal cord, and nerves. The nervous system receives and processes information from the senses, sends signals to muscles and glands, and helps regulate bodily functions.

Muscular System

The muscular system is responsible for movement and locomotion. It includes three types of muscles: skeletal muscles, which are attached to bones and allow voluntary movement; smooth muscles, which control involuntary movements in organs; and cardiac muscles, which make up the heart and control its contractions.

Excretory System

The excretory system is responsible for removing waste products from the body. It includes organs such as the kidneys, ureters, bladder, and urethra. The excretory system filters waste products from the blood and eliminates them in the form of urine.

Circulatory/Cardiovascular System

The circulatory system, also known as the cardiovascular system, is responsible for transporting oxygen, nutrients, hormones, and waste products throughout the body. It includes the heart, blood vessels, and blood. The circulatory system helps maintain homeostasis and supports the functioning of other organ systems.

Respiratory System

The respiratory system is responsible for the exchange of oxygen and carbon dioxide between the body and the environment. It includes organs such as the nose, trachea, bronchi, and lungs. The respiratory system allows for the intake of oxygen and the removal of carbon dioxide, supporting cellular respiration.

Immune System

The immune system is responsible for defending the body against pathogens, such as bacteria, viruses, and parasites. It includes organs such as the thymus, bone marrow, lymph nodes, and spleen, as well as specialized cells and molecules. The immune system recognizes and destroys foreign substances, protecting the body from infections and diseases.

Homeostasis

The maintenance of a constant internal state in a changing environment

Reproductive System

Responsible for the production of offspring. In males, it includes the testes, penis, and associated structures, while in females, it includes the ovaries, uterus, and vagina. A common phrase recommended for use with students is “to provide for the continuation of the species”.

Endocrine System

System responsible for producing and regulating hormones, which are chemical messengers that control various bodily functions; Includes glands such as the pituitary gland, thyroid gland, adrenal glands, and pancreas; Plays a crucial role in growth, metabolism, reproduction, and response to stress.

Integumentary System

The body's largest organ system; Includes the skin, hair, and nails; Provides protection against external threats, regulates body temperature, and helps with the excretion of waste products; Skin also contains sensory receptors that allow us to sense touch, pressure, and temperature.

Lymphatic System

A network of vessels, nodes, and organs that helps maintain fluid balance and defend the body against infections; Includes lymph nodes, lymphatic vessels, the spleen, and the thymus gland; Plays a crucial role in immune function and the removal of waste products.

Skeletal System

Provides support, protection, and movement for the body; Made up of bones, cartilage, ligaments, and tendons; Also produces blood cells and stores minerals such as calcium and phosphorus.