TEAS science: anatomy and physiology study guide

Body orientation: positions, planes and cavities

Everything is described from anatomical position: standing upright, facing forward, arms at the sides, palms forward.

The sagittal plane divides the body into left and right (midsagittal: into equal halves). The frontal (coronal) plane divides front from back. The transverse plane divides top from bottom. The dorsal cavity holds the cranial cavity (brain) and the vertebral canal (spinal cord); the ventral cavity holds the thoracic cavity (lungs and heart) and, below the diaphragm, the abdominopelvic cavity.

Support and movement: skeletal and muscular systems

The adult skeleton has 206 bones. It supports and protects the body, anchors muscles, stores minerals such as calcium, and makes blood cells in red bone marrow. The axial skeleton is the skull, vertebral column and rib cage; the appendicular skeleton is the limbs plus the shoulder and pelvic girdles. Ligaments join bone to bone; tendons join muscle to bone.

There are three muscle types. Skeletal muscle is striated and voluntary. Cardiac muscle is striated, involuntary and found only in the heart. Smooth muscle is non-striated and involuntary, lining hollow organs such as the stomach and blood vessels. Skeletal muscles work in pairs: when the agonist contracts, the antagonist relaxes (the biceps flexes the elbow, the triceps extends it). Contraction happens when actin and myosin filaments slide past each other, powered by ATP and triggered by calcium.

Control: nervous and endocrine systems

The central nervous system is the brain and spinal cord; the peripheral nervous system is every nerve outside them. The peripheral system's autonomic branch runs involuntary functions: sympathetic (fight or flight: faster heart rate, dilated pupils, slowed digestion) and parasympathetic (rest and digest). A neuron receives signals through dendrites and sends them along its axon; the myelin sheath speeds conduction. The cerebrum handles thought and voluntary movement, the cerebellum coordination and balance, and the brainstem breathing and heart rate.

The endocrine system controls the body more slowly, through hormones carried in the blood. Know the pairs: the pituitary (often called the master gland) releases hormones that direct other glands; the thyroid sets metabolic rate; the pancreas releases insulin (lowers blood glucose) and glucagon (raises it); the adrenal glands release epinephrine and cortisol; the ovaries and testes release sex hormones. Most hormone levels are held steady by negative feedback.

Transport and exchange: cardiovascular and respiratory systems

Blood returning from the body enters the right atrium, passes to the right ventricle, and is pumped through the pulmonary arteries to the lungs. Oxygen-rich blood returns through the pulmonary veins to the left atrium, then the left ventricle, which pumps it out through the aorta. Arteries carry blood away from the heart and veins carry it back; the pulmonary vessels are the exception to the oxygen rule. Capillaries are where exchange with the tissues happens.

Air travels through the nose, pharynx, larynx, trachea, bronchi and bronchioles to the alveoli, where oxygen diffuses into the blood and carbon dioxide diffuses out. The diaphragm contracts and moves down during inhalation, enlarging the chest cavity and drawing air in. Breathing rate is driven mainly by carbon dioxide levels in the blood.

Processing: digestive and urinary systems

Food moves from the mouth through the esophagus, stomach, small intestine (duodenum, jejunum, ileum) and large intestine. Chemical digestion begins in the mouth with salivary amylase. Most digestion and absorption happen in the small intestine, whose villi enlarge its surface; the large intestine absorbs water. The liver makes bile, the gallbladder stores it, and bile emulsifies fats. The pancreas sends digestive enzymes into the duodenum.

The urinary system is two kidneys, two ureters, the bladder and the urethra. The working unit of the kidney is the nephron: blood is filtered at the glomerulus, and useful substances are reabsorbed along the tubule. The kidneys balance water, electrolytes and pH, and antidiuretic hormone (ADH) tells them to conserve water.

Protection and continuity: integumentary, immune and reproductive systems

The skin has an outer epidermis, a dermis with blood vessels, nerves, glands and hair follicles, and the subcutaneous layer beneath. It protects, regulates temperature by sweating and changing blood flow, senses touch and pain, and starts vitamin D production.

The immune system's first defenses are barriers such as skin and mucus. The innate response (inflammation, fever, phagocytes) is fast and general. The adaptive response is specific and has memory: B cells make antibodies and T cells attack infected cells and coordinate the response. The lymphatic system returns tissue fluid to the blood and filters it through lymph nodes; the spleen filters blood.

In reproduction, the testes produce sperm and testosterone; the ovaries produce eggs, estrogen and progesterone. Fertilization usually happens in the uterine (fallopian) tube, and the embryo implants in the uterus.

How to study A&P for the TEAS

Learn one system at a time with the same four questions: what are its organs, what does it do, what controls it, and what other system does it depend on. Then test yourself with mixed questions, because the real test jumps between systems. Build a word-part habit as you go (cardi- heart, nephr- kidney, gastr- stomach, -itis inflammation): it helps in the English vocabulary questions too. Try the anatomy and physiology practice set, then the broader science practice set.