TEAS anatomy and physiology: the eleven body systems

The eleven body systems as a TEAS question asks them — main parts and primary function for each — plus the four distinctions that decide the answer: function versus product, structure versus function, organs shared by two systems, and direction of flow.

A useful way to study TEAS anatomy and physiology is to ask two questions of each system: which parts belong to it, and what job it does. This page is the reference for both — the eleven body systems, each with its main organs and its primary function, in the form a question is likely to ask for, plus the structures that trip people up inside each one.

Human anatomy and physiology carries ATI's published weight of 12% of the exam and 18 of the science section's 44 scored items — tied with numbers and algebra as the largest sub-content area on the exam, and the largest in the science section. The tables below restate OpenStax Anatomy and Physiology 2e (2022, CC BY 4.0), chapters 1 and 5–28.

The eleven systems

System	Main parts	Primary function
Integumentary	Skin, hair, nails, sweat and oil glands	Barrier against injury and infection, temperature regulation, vitamin D synthesis, sensation
Skeletal	Bones, cartilage, ligaments, joints	Support and protection, levers for movement, blood cell production, mineral storage
Muscular	Skeletal muscles and their tendons (smooth and cardiac muscle are tissues of other organs)	Movement and posture, heat production, moving material through hollow organs
Nervous	Brain, spinal cord, nerves, sensory receptors	Detecting change, integrating it, and producing a rapid response
Endocrine	Hypothalamus, pituitary, thyroid, parathyroid, adrenal glands, pancreas, gonads	Hormones that regulate growth, metabolism, reproduction and stress
Cardiovascular	Heart, blood, arteries, veins, capillaries	Transporting gases, nutrients, wastes and heat; carrying immune cells
Lymphatic and immune	Lymph, lymphatic vessels, lymph nodes, spleen, thymus, tonsils	Returning tissue fluid to the blood and defending against pathogens
Respiratory	Nasal cavity, pharynx, larynx, trachea, bronchi, lungs, and the diaphragm that drives breathing	Gas exchange — bringing in oxygen, removing carbon dioxide — and helping regulate pH
Digestive	Mouth, esophagus, stomach, small and large intestine, liver, gallbladder, pancreas	Breaking food down, absorbing nutrients and water, eliminating waste
Urinary	Kidneys, ureters, bladder, urethra	Filtering blood, forming urine, regulating fluid, electrolytes, pH and blood pressure
Reproductive	Ovaries or testes, plus ducts and accessory glands	Producing gametes and the hormones that govern reproduction

The four distinctions worth drilling

Four distinctions are worth drilling, and each one has a fix:

Function versus product. The liver produces bile; the gallbladder stores it. The pancreas makes digestive enzymes and the hormones insulin and glucagon, so it sits in two systems and belongs to both lists.
Structure versus function. Ligaments join bone to bone; tendons join muscle to bone. Both are connective tissue, and the two words are easy to swap under time pressure.
Two systems, one organ. The pharynx is shared by the respiratory and digestive systems; in the male body the urethra carries both urine and semen, so one organ can belong to two lists.
Direction of flow. Veins carry blood toward the heart and arteries away from it, regardless of what the blood is carrying — which is the one fact that resolves both the pulmonary-circuit trap and the umbilical-vessel trap.

How to study a system, not a list

Learn each system in three passes. First the parts, as names. Then the function, in one sentence you could say out loud. Then the one connection that joins it to its neighbor — how the digestive system's absorbed nutrients reach the cardiovascular system, why the respiratory system's gas exchange depends on the circulatory system's capillaries.

The third pass is where the study pays, because a connection is the part a list of names cannot give you.

Where to practice this

Human anatomy and physiology practice — the free set, with an explanation on every item
Human anatomy and physiology guide — the method and the worked items
Science practice — the whole section, all four sub-content areas

The section is 50 items in 60 minutes, and the other 26 scored items are biology, chemistry, and scientific reasoning.

Source: OpenStax Anatomy and Physiology 2e (2022, CC BY 4.0), chapters 1 and 5–28.

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