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Bio 20 Unit B
| Question | Answer |
|---|---|
| What are the six major functions of the circulatory system? | Removes waste, distributes heat, maintains body fluid levels, carries antibodies, carries hormones, and supplies cells with nutrients and oxygen. |
| What are arteries and arterioles? | Vessels that carry blood away from the heart; thick, elastic, muscular walls; branch into smaller arterioles. |
| What is vasodilation? | Relaxation of arterial walls to increase blood flow when oxygen demand rises. |
| What is vasoconstriction? | Constriction of arterial walls to reduce blood flow and conserve heat. |
| What are capillaries? | Tiny, one-cell-thick vessels where gas and nutrient exchange occurs between blood and tissues. |
| What are veins and venules? | Vessels carrying blood toward the heart; thinner walls; contain valves to prevent backflow. |
| What is the function of the lymphatic system? | Collects excess tissue fluid and returns it to the bloodstream; supports immune function. |
| Where is the heart located and what is it made of? | Located behind the breastbone, roughly fist-sized, made of cardiac muscle tissue divided into right and left halves by a septum. |
| What are atria and ventricles? | Atria are upper chambers that receive blood; ventricles are lower chambers that pump blood out of the heart. |
| What are the AV and semilunar valves? | AV valves separate atria and ventricles; semilunar valves prevent blood from flowing back into the heart from arteries. |
| What is the cardiac cycle? | One complete heartbeat involving contraction (systole) and relaxation (diastole) of the heart chambers. |
| What is cardiac output? | The amount of blood pumped by the heart per minute (heart rate × stroke volume). |
| What controls heart rhythm internally? | The sinoatrial (SA) node acts as the heart’s natural pacemaker, initiating electrical impulses. |
| What is the function of an artificial pacemaker? | An implanted device that regulates heart rhythm when the SA node fails. |
| How does the nervous system affect heart rate? | Sympathetic nerves speed up heart rate during stress; parasympathetic nerves slow it down during rest. |
| What factors increase heart rate? | Exercise, temperature, stress, hormones (e.g., adrenaline), and high CO₂ levels. |
| What are the two circulatory loops in humans? | Pulmonary circulation (heart to lungs) and systemic circulation (heart to body). |
| What is plasma? | Straw-colored liquid making up ~55% of blood; mostly water with ions, proteins, and nutrients. |
| What are red blood cells? | Biconcave cells without nuclei that carry oxygen via hemoglobin; live ~120 days. |
| What is anemia? | A condition caused by low iron or hemoglobin, leading to fatigue and reduced oxygen transport. |
| What are white blood cells? | Cells that fight infection through phagocytosis, antibody production, or enzyme secretion. |
| What are platelets? | Cell fragments that trigger clotting by releasing thromboplastin, forming fibrin threads to seal wounds. |
| What are the four main blood types? | A, B, AB, and O, determined by surface antigens and antibodies present in plasma. |
| What is the Rh factor? | An additional antigen on red blood cells determining positive or negative blood type. |
| How does the body defend against pathogens? | Using barriers (skin, mucus, acid) and internal defenses (phagocytes, antibodies). |
| What is inflammation? | A localized response where white blood cells attack pathogens and damaged cells, causing redness and swelling. |
| What is immunity? | The body's ability to recognize and destroy pathogens through antibody production by lymphocytes. |
| What do T cells do? | Identify infected cells and coordinate immune responses by signaling B cells and killer T cells. |
| What do B cells do? | Produce antibodies and form memory cells for long-term immunity. |
| What are vaccines? | Weakened or inactive pathogens that trigger antibody production without causing disease. |
| What are antibiotics? | Drugs that kill bacteria by disrupting cell wall formation or other vital processes. |
| Why should antibiotics be used carefully? | Overuse leads to resistance, allergic reactions, and destruction of helpful bacteria. |
| What are the four main stages of digestion? | Ingestion, digestion, absorption, and excretion. |
| What happens during ingestion? | Food is taken into the mouth and physically broken down by teeth and saliva. |
| What enzymes are in saliva? | Amylase (breaks starch into maltose) and mucin (lubricates food). |
| What is the esophagus? | Muscular tube that moves food from the pharynx to the stomach using peristalsis. |
| What is the stomach’s function? | Stores and liquefies food, starts protein digestion using acid and enzymes. |
| What are the components of gastric juice? | Hydrochloric acid, pepsin, mucus, and hormones such as gastrin. |
| What is the small intestine’s role? | Completes digestion and absorbs nutrients through villi lined with capillaries and lacteals. |
| What is bile? | A fluid from the liver stored in the gallbladder that emulsifies fats for digestion. |
| What does the pancreas do? | Produces digestive enzymes (amylase, trypsin, lipase) and bicarbonate to neutralize stomach acid. |
| What is the liver’s function? | Processes nutrients, detoxifies substances, produces bile, and regulates blood sugar. |
| What does the large intestine do? | Absorbs water and vitamins, stores waste, and forms feces. |
| What is the excretory system’s main function? | Removes metabolic wastes and maintains water and salt balance. |
| What is urine formation? | Filtration, reabsorption, and secretion in the nephrons of the kidneys. |
| What is the role of the nephron? | Filters blood, reabsorbs needed substances, and secretes wastes into urine. |
| What does ADH do? | Increases water reabsorption in the kidneys, reducing urine output. |
| What does aldosterone do? | Increases sodium reabsorption and water retention, raising blood pressure. |
| What are diuretics? | Chemicals that increase urine production by reducing water reabsorption. |
| What is kidney dialysis? | A process that filters blood when kidneys fail, using a semipermeable membrane. |
| What are the three types of muscle tissue? | Cardiac, smooth, and skeletal muscle. |
| What is skeletal muscle? | Voluntary, striated muscle that moves bones and produces heat. |
| What is smooth muscle? | Involuntary, non-striated muscle in organs and vessels. |
| What is cardiac muscle? | Involuntary, striated muscle that forms the heart wall and beats automatically. |
| What is the sliding filament theory? | Muscle contraction occurs when actin filaments slide over myosin filaments, shortening the sarcomere. |
| What causes muscle fatigue? | Lactic acid buildup and ATP depletion after prolonged activity. |
| What are the main organs of the respiratory system? | Nose, pharynx, trachea, bronchi, lungs, and diaphragm. |
| What happens during inhalation? | Diaphragm and intercostal muscles contract, expanding the chest cavity and drawing air in. |
| What happens during exhalation? | Muscles relax, chest cavity decreases, and air is forced out. |
| What are alveoli? | Tiny air sacs in the lungs where gas exchange occurs with capillaries. |
| How is oxygen transported in the blood? | Bound to hemoglobin forming oxyhemoglobin. |
| How is carbon dioxide transported in the blood? | Dissolved in plasma, bound to hemoglobin, or as bicarbonate ions. |
| What controls breathing rate? | Chemoreceptors in the medulla detect CO₂ levels and adjust respiration accordingly. Chemoreceptors in the major arteries also check for low oxygen levels |
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