A free, self-paced textbook in 8 chapters. Read a chapter, then drill it with the 1004 companion flashcards using spaced repetition.
The human body is organized into hierarchical systems that work together to maintain life. The largest organ is the skin, part of the integumentary system, covering approximately 1...
The cardiovascular system centers on the heart and blood vessels. Arteries carry oxygenated blood away from the heart (except the pulmonary arteries) under high pressure and have t...
The digestive tract breaks down food mechanically and chemically, absorbing nutrients primarily in the small intestine and water in the large intestine. Common conditions include g...
The endocrine system is a network of glands producing hormones that regulate metabolism, growth, reproduction, and mood. Major glands include the pituitary (the "master gland" cont...
Blood consists of red blood cells (carrying oxygen via hemoglobin, vastly outnumbering white blood cells at about 700:1), white blood cells (fighting infection), platelets (enablin...
Vital signs provide rapid assessment of physiological status. A normal resting heart rate for adults is 60–100 beats per minute, with well-trained athletes often having resting rat...
Pharmacology encompasses how drugs interact with the body. Pharmacokinetics describes what the body does to a drug through absorption, distribution, metabolism, and excretion (ADME...
First aid knowledge can be lifesaving in emergencies. For an unresponsive adult requiring CPR, the rescuer should call emergency services, place the person on a firm surface, posit...