TEAS Test of Essential Academic Skills - Set 3 - Part 1

Correct Answer: Distal

Distal means farther from the point of origin or attachment of a limb. The fingers are distal to the elbow, and the toes are distal to the knee. Option a is incorrect because proximal means closer to the trunk or point of origin, which is the direct opposite of distal in standard anatomical terminology. Option b is incorrect because medial refers to a position closer to the midline of the body and does not describe distance from a point of origin. Option d is incorrect because superficial means closer to the body surface, an entirely different directional term unrelated to distance from origin.

Correct Answer: Transverse plane

The transverse, or horizontal, plane divides the body into superior upper and inferior lower portions. A computed tomography slice provides a transverse view of the body. Option b is incorrect because the sagittal plane is a vertical cut that divides the body into left and right portions, not superior and inferior portions. Option c is incorrect because the frontal or coronal plane divides the body into anterior front and posterior back portions, not superior and inferior. Option d is incorrect because the midsagittal plane is a vertical cut down the midline producing equal left and right halves, not superior and inferior portions.

Correct Answer: Thoracic cavity

The thoracic cavity, part of the ventral cavity, houses the lungs in the pleural cavities and the heart, esophagus, and major vessels in the mediastinum, separated from the abdomen by the diaphragm. Option a is incorrect because the abdominopelvic cavity contains digestive, urinary, and reproductive organs, not the heart, lungs, or thoracic structures of the mediastinum. Option b is incorrect because the cranial cavity is a subdivision of the dorsal cavity that houses only the brain, not thoracic organs such as the heart or lungs. Option c is incorrect because the spinal cavity is part of the dorsal cavity and houses the spinal cord, not the heart, lungs, or other thoracic contents.

Correct Answer: Alveoli

Alveoli are tiny sacs surrounded by capillaries with walls one cell thick. Oxygen and carbon dioxide diffuse across this thin barrier, making alveoli the true site of pulmonary gas exchange. Option a is incorrect because the trachea is a conducting airway that warms and channels air to the bronchi but does not participate in gas exchange itself. Option c is incorrect because the bronchi are conducting passages that branch from the trachea into each lung but lack the thin walls needed for gas exchange. Option d is incorrect because bronchioles are smaller conducting airways leading to alveoli; they channel air but do not perform actual gas exchange.

Correct Answer: Epiglottis

The epiglottis is a flap of cartilage that folds down over the laryngeal opening during swallowing, directing food and liquid into the esophagus and protecting the airway from aspiration. Option a is incorrect because the pharynx is the shared throat passage for both food and air; it does not actively close off the airway during swallowing. Option b is incorrect because the larynx is the voice box that houses the vocal cords; it is the structure being protected, not the protector itself. Option d is incorrect because the soft palate elevates to seal off the nasopharynx during swallowing, not the lower airway leading to the lungs.

Correct Answer: Diaphragm

The diaphragm is the dome-shaped main muscle of breathing. When it contracts, it flattens, expanding the thoracic cavity and lowering pressure so air rushes into the lungs. Option b is incorrect because the pectoralis major is a chest muscle used for arm movement; it can be an accessory muscle but is not the primary breathing muscle. Option c is incorrect because the latissimus dorsi is a broad back muscle that moves the arm; it does not function as the main muscle of inspiration. Option d is incorrect because the sternocleidomastoid rotates and flexes the head and acts only as an accessory muscle of breathing during forceful inspiration.

Correct Answer: Bicarbonate ions in plasma

About seventy percent of carbon dioxide in blood is carried as bicarbonate ions dissolved in plasma. Smaller amounts travel bound to hemoglobin or dissolved directly as carbon dioxide gas. Option a is incorrect because only about seven percent of carbon dioxide is carried dissolved as gas in plasma, far less than the bicarbonate fraction in venous transport. Option b is incorrect because carbon dioxide does not bind directly to oxygen molecules; it binds hemoglobin separately at amino groups, not to oxygen itself. Option c is incorrect because carbaminohemoglobin accounts for about twenty-three percent of carbon dioxide transport, less than the dominant bicarbonate ion fraction in plasma.

Correct Answer: Left atrium

The left atrium receives freshly oxygenated blood returning from the lungs by way of the four pulmonary veins. It then pumps the blood through the mitral valve into the left ventricle. Option a is incorrect because the right atrium receives deoxygenated blood from the body via the superior and inferior vena cavae, not oxygenated blood from the lungs. Option b is incorrect because the right ventricle pumps deoxygenated blood out to the lungs through the pulmonary arteries; it does not receive blood from the lungs. Option d is incorrect because the left ventricle receives oxygenated blood from the left atrium, not directly from the pulmonary veins entering the heart.

Correct Answer: Tricuspid valve

The tricuspid valve sits between the right atrium and right ventricle. It allows blood to flow from atrium to ventricle and prevents backflow during ventricular contraction. Option a is incorrect because the mitral, or bicuspid, valve sits between the left atrium and the left ventricle on the oxygenated side of the heart. Option c is incorrect because the aortic valve sits between the left ventricle and the aorta; it is a semilunar outflow valve, not an atrioventricular valve. Option d is incorrect because the pulmonary valve sits between the right ventricle and the pulmonary artery; it controls outflow rather than the atrium-to-ventricle opening.

Correct Answer: Sinoatrial node

The sinoatrial node, located in the right atrium, generates spontaneous electrical impulses that set the heart rate. It is therefore called the natural pacemaker of the heart. Option b is incorrect because the atrioventricular node receives the signal from the sinoatrial node and delays it, but does not initiate the heartbeat itself. Option c is incorrect because the bundle of His conducts impulses from the atrioventricular node into the ventricles; it does not originate the cardiac rhythm. Option d is incorrect because Purkinje fibers spread the impulse through the ventricular walls, causing contraction; they conduct the signal but do not generate it.

Correct Answer: Walls that are only one cell thick

Capillaries have walls only one endothelial cell thick. This minimal barrier allows oxygen, carbon dioxide, nutrients, and waste to diffuse rapidly between blood and surrounding tissues. Option a is incorrect because thick muscular walls are characteristic of arteries, which must withstand high pressure; such walls would block diffusion across capillaries. Option b is incorrect because one-way valves are found in veins to prevent backflow against gravity; capillaries do not contain valves of any type. Option c is incorrect because elastic recoil walls are typical of large arteries near the heart; capillaries are not designed to expand and recoil with pressure.

Correct Answer: Forming blood clots after injury

Platelets, also called thrombocytes, initiate clotting by aggregating at injury sites and releasing factors. Low platelet counts impair clot formation, leading to easy bruising and prolonged bleeding. Option a is incorrect because oxygen transport is the role of red blood cells using hemoglobin, not platelets; oxygen delivery is unaffected by platelet count. Option b is incorrect because fighting bacterial infections is the function of white blood cells, especially neutrophils and lymphocytes, rather than the clotting platelets. Option d is incorrect because blood pressure depends on cardiac output and vessel resistance, not platelet count; low platelets do not directly lower blood pressure.

Correct Answer: Aorta

The aorta is the largest artery in the body. It leaves the left ventricle and branches into smaller arteries that deliver oxygenated blood throughout the systemic circulation. Option b is incorrect because the pulmonary artery leaves the right ventricle carrying deoxygenated blood to the lungs, not oxygenated blood from the left ventricle to the body. Option c is incorrect because the carotid artery is a branch of the aorta supplying the head and neck; it is not the vessel directly leaving the left ventricle. Option d is incorrect because the vena cava is the major vein returning deoxygenated blood to the right atrium, not an artery leaving the left ventricle.

Correct Answer: Small intestine

Most chemical digestion happens in the small intestine, especially the duodenum. Pancreatic enzymes and bile complete the breakdown of carbohydrates, proteins, and fats into absorbable molecules. Option a is incorrect because the stomach mainly initiates protein digestion with pepsin and acid; most chemical digestion is finished later in the small intestine. Option c is incorrect because the large intestine primarily absorbs water and electrolytes and houses bacteria; it does not perform significant chemical digestion. Option d is incorrect because the mouth begins only carbohydrate digestion through salivary amylase; the bulk of chemical digestion occurs much further along.

Correct Answer: Liver

The liver produces bile continuously. Bile then passes to the gallbladder for storage and concentration before being released into the duodenum to emulsify dietary fats. Option a is incorrect because the pancreas produces digestive enzymes and bicarbonate, plus the hormones insulin and glucagon, but it does not produce bile. Option b is incorrect because the gallbladder only stores and concentrates bile that arrives from the liver; it does not synthesize bile itself. Option c is incorrect because the stomach produces hydrochloric acid and pepsin to begin protein digestion; it does not produce bile or emulsify fats.

Correct Answer: Villi and microvilli

The small intestinal lining has finger-like villi covered with even smaller microvilli on each cell. Together, they enormously increase surface area, maximizing absorption of digested nutrients into the blood. Option a is incorrect because the pyloric sphincter is a muscular ring that controls passage of chyme from the stomach to the duodenum, not a structure increasing surface area. Option b is incorrect because rugae are the folds inside the stomach wall that allow it to stretch with food; they are not the absorption-enhancing folds of the intestine. Option d is incorrect because haustra and taeniae coli are anatomical features of the large intestine; they shape the colon but do not produce villi for absorption.

Correct Answer: Peristalsis

Peristalsis is the rhythmic, wave-like contraction of smooth muscle in the digestive tract walls. It steadily moves food from the esophagus through the stomach, intestines, and rectum. Option b is incorrect because mastication is the chewing of food in the mouth; it breaks food mechanically but does not propel it through the entire digestive tract. Option c is incorrect because emulsification is the breakdown of fat globules into smaller droplets by bile, a chemical process unrelated to muscular propulsion. Option d is incorrect because defecation is the elimination of feces from the rectum through the anus, a final event rather than the ongoing transport mechanism.

Correct Answer: Proteins

Pepsin is a stomach enzyme that begins the chemical breakdown of proteins into smaller peptides. Reduced pepsin directly impairs early protein digestion before further breakdown in the small intestine. Option a is incorrect because carbohydrate digestion is started by salivary amylase and continued by pancreatic amylase; pepsin does not break down carbohydrates at all. Option b is incorrect because lipid digestion depends on bile from the liver and pancreatic lipase in the small intestine; pepsin has no role in fat digestion. Option c is incorrect because nucleic acids are digested mainly by pancreatic nucleases in the small intestine; pepsin does not act on nucleic acids in the stomach.

Correct Answer: Central nervous system

The central nervous system consists of the brain and spinal cord. It integrates sensory information and issues motor commands while the peripheral nervous system carries signals to and from these structures. Option a is incorrect because the somatic nervous system is a subdivision of the peripheral nervous system controlling voluntary skeletal muscle movement; it does not include the brain. Option c is incorrect because the autonomic nervous system is part of the peripheral nervous system controlling involuntary functions; it does not contain the brain or spinal cord. Option d is incorrect because the peripheral nervous system includes all nerves outside the central nervous system; it specifically excludes the brain and spinal cord.

Correct Answer: Occipital lobe

The occipital lobe is located at the back of the cerebrum and contains the primary visual cortex. It receives and processes signals arriving from the eyes through the optic pathway. Option a is incorrect because the frontal lobe handles voluntary movement, planning, decision-making, and personality; vision is not its primary processing role. Option b is incorrect because the parietal lobe processes somatosensory information such as touch, temperature, and spatial awareness, not visual signals from the eyes. Option d is incorrect because the temporal lobe handles hearing, language understanding through Wernicke's area, and memory formation rather than visual processing.