Biological Levels of Organization and Human Body Systems

Cells

Building blocks of living things.

Tissues

Group of cells.

Organs

Made of several types of tissues that have only one function (heart, lungs, liver etc.).

Organ System

Group of organs working together to perform one or more functions.

Organism

A living thing.

Nervous System

Includes Brain, Spinal Cord, nerves; functions as it sends back and forth signals between brain and body.

Endocrine System

Includes complex network of glands and organs; functions as controlling hormones to control body's metabolism, energy level, reproduction, growth/development, response to injury/stress/mood.

Skeletal System

Includes 206 bones, tendons, joints, ligaments; functions as a foundation for muscles and aid in mobility.

Muscular System

Cells made from muscle fibers; function is to move and contract skeleton; includes heart muscles, smooth muscles, skeletal muscles; attached to bone then to skin.

Integumentary System

Includes skin, hair, nails & other organs; functions as body's first line of defense, keeps body warm and from infection.

Cardiovascular System

Includes heart and blood vessels; functions is to deliver oxygen/nutrients/hormones throughout the cells/organs of the body.

Respiratory System

Includes lungs, diaphragm, trachea, bronchioles; function is for breathing, supplying oxygen to body.

Circulatory System

Includes heart, arteries, veins, capillaries; functions to distribute nutrients to cells and pump blood to body.

Arteries

Carry blood away from the heart.

Veins

Carry blood back to the heart.

Capillaries

Connect arteries and veins.

Lymphatic System

Drainage system that maintains balance of fluids in the body, keeps body from infections; includes bone marrow, lymph nodes, thymus.

Digestive System

Function is to absorb and digest solids; made up of GI TRACT (digestive tract), a long twisted tube that runs down from mouth to anus.

Reproductive System

Involves internal/external organs that allow to produce; includes testicles, scrotum, penis, prostate, vagina.

Urinary System

Includes kidney, urethra, bladder, ureters; eliminates waste, keeps body fluids balanced, controls pH/electrolyte level.

Diabetes mellitus

Decline in pancreas insulin production.

Multiple sclerosis

Weak muscles due to loss of coating in nerves.

Atrophy

Reduction in muscle mass.

Hypertension

Blood pressure is too high.

Arteriosclerosis

Artery walls too thick.

Pneumonia

A respiratory condition.

Asthma

A respiratory condition.

Hepatitis

Liver inflammation.

Ulcer

Disintegration of GI TRACT/small intestine.

Diarrhea

Watery stool.