Hewitt/Lyons/Suchocki/Yeh Conceptual Integrated Science

1. Hewitt/Lyons/Suchocki/YehConceptual Integrated Science Chapter 20 HUMAN BIOLOGY II— CARE AND MAINTENANCE

2. This lecture will help you understand: • Integration of Body Systems • The Circulatory System • Integrated Science—Hemoglobin • Respiration • Digestion • Nutrition, Exercise, and Health • Integrated Science—Diets • Excretion and Water Balance • Keeping the Body Safe: Defense Systems • Technology: Transplanting Bone Marrow • Science and Society: What Are the Odds? • Science and Society: The Placebo Effect • Science and Society: AIDS

3. Integration of Body Systems The body’s systems rarely act alone. Bodily functions usually require two or more organ systems. Example: Obtaining oxygen for the cells requires the coordination of the respiratory and circulatory systems.

4. Integration of Body Systems CHECK YOUR NEIGHBOR What body systems are involved in disposing cellular wastes? Explain your answer to your neighbor.

5. Integration of Body Systems CHECK YOUR ANSWER Three systems work together to dispose of cellular wastes: The circulatory system collects wastes from the tissues. The respiratory and excretory systems remove them from the body.

6. The Circulatory System The circulatory system consists of three components: • Heart • Blood vessels • Blood The circulatory system is the body’s system for moving things around.

7. The Circulatory System The right side of the heart pumps blood to the lungs to pick up oxygen. The left side pumps blood to the rest of the body.

8. The Circulatory System Every heartbeat begins in the pacemaker—the sinoatrial node. The pacemaker initiates an action potential that causes the right and left atria to contract simultaneously. The signal also passes to the atrioventricular node and then to the two ventricles, which also contract simultaneously.

9. The Circulatory System Blood vessels are tubes that carry blood: • Arteries carry blood away from the heart into arterioles and then into capillaries. • Capillaries are thin walled and do not have smooth muscle surrounding them. In the capillaries, materials move between tissues and blood. • Venules carry blood back to veins, which return the blood to the heart.

10. The Circulatory System When we move, our muscle contractions squeeze blood along the veins. Valves ensure that blood does not flow backwards. When we sit for a long time, what happens to our blood?

11. The Circulatory System Our blood is composed of: • Plasma —Water, salts, proteins, hormones, glucose, other nutrients, wastes • Cells • Red blood cells—carry oxygen, do not have a nucleus or mitochondria. Red blood cells die and must be replaced frequently. • White blood cells—immune cells, defend our bodies against disease • Platelets—function in blood clotting

12. Integrated Science—Hemoglobin Hemoglobin protein carries the oxygen in our red blood cells. Hemoglobin consists of four subunits. Each subunit contains a heme group that includes one iron atom. The iron binds oxygen. Each hemoglobin molecule can carry up to four molecules of oxygen.

13. Integrated Science—Hemoglobin When one of the heme groups binds to an oxygen molecule, the other three heme groups are altered to make them more likely to bind oxygen as well. The reverse occurs, too. When one heme group unloads an oxygen molecule, the other groups are altered to be more likely to give up their oxygen.

14. Respiration Through breathing, the respiratorysystem moves oxygen to the circulatory system from the air. Gas exchange occurs through diffusion in the alveoli of the lungs. Oxygen diffuses into capillaries, and carbon dioxidediffuses from capillaries into thealveoli.

15. Respiration As air passes the larynx, it vibrates the vocal cords, generating sound waves. We control the muscles that stretch the vocal chords to produce the sounds of speech.

16. Respiration We move air in and out of our lungs using a set of muscles: • The diaphragm and muscles between our ribs contract, the chest cavity expands, air pressure drops, and air is sucked into the chest. • The diaphragm and rib muscles relax, decreasing the volume of the thoracic cavity, forcing air out.

17. Digestion We rely on food: • To supply us with organic molecules for energy • To provide essential molecules that we cannot produce on our own • To help us maintain a stable body temperature

18. Digestion The digestive system consists of several parts: • The mouth—teeth, saliva, tastebuds, tongue • Esophagus—moves food via peristalsis until it reaches a sphincter leading to the stomach • Stomach—gastric juice and churning action reduce food to chyme • Small intestine—breaks down proteins, fats, carbohydrates, and nucleic acids and conducts absorption of nutrients • Large intestine—absorbs water and minerals and produces feces

19. Nutrition, Exercise, and Health For good health, the human body needs • An adequate number of calories • Essential nutrients such as amino acids that the body cannot produce • Vitamins and minerals that the body cannot produce • Exercise!

20. Integrated Science—Diets Both low carb and low calorie diets help us lose weight because we consume fewer calories. However, low carb diets: • Reduce water retention • Tend to be high in saturated fats and cholesterol • Are low in whole grains and fruit

21. Excretion and Water Balance The excretory system: • Filters our blood, removing wastes • Controls the retention or excretion of ions and water Excretion begins in the kidneys.

22. Excretion and Water Balance Fluid enters the nephron from the circulatory system. The loop of Henle reabsorbs water from the filtrate. In the distal convoluted tubule, additional wastes are added to the filtrate. In the collecting duct, water may be reabsorbed.

23. Excretion and Water Balance

24. Excretion and Water Balance From the collecting duct, urine flows into the renal pelvis, down the ureter, and into the bladder. It is excreted out the urethra.

25. Keeping the Body Safe: Defense Systems The immune system consists of two parts: • Innate immunity—nonspecific—works against a wide variety of pathogens • Acquired immunity—specific—cells recognize certain very specific features of pathogens Acquired immunity is found only in vertebrates (probably).

26. Keeping the Body Safe: Defense Systems Our immune systems consists of many tissues and organs, including: • Bone marrow—produces all immune cells (“white” blood cells) • Thymus • Lymphatic system • Spleen • Skin

27. Keeping the Body Safe: Defense Systems The innate immune system relies on: • The skin (tough outer layer, shedding of cells, acidic secretions from hair follicles) • Saliva, tears, sweat, milk • Mucous membranes • Response from innate immune cells • Inflammatory response

28. Keeping the Body Safe: Defense Systems The inflammatory response occurs when damaged tissues release histamines, which increase blood flow to the site, cause capillaries to leak, and attract innate immune cells.

29. Keeping the Body Safe: Defense Systems Each cell of the acquired immune system has receptors that recognize a single antigen—a molecule or part of a molecule belonging to a pathogen. The acquired immune system takes longer to deploy but retains a memory of pathogens so that it can respond more quickly and aggressively the next time the pathogen is encountered.

30. Keeping the Body Safe: Defense Systems There are two types of acquired immune cells: B cells target pathogens in body fluids. T cells target pathogens inside the body’s cells.

31. Keeping the Body Safe: Defense Systems B cells divide and release antibodies. Some clones become memory cells that stay in the body.

32. Keeping the Body Safe: Defense Systems Helper T cells organize the acquired immune response. They stimulate B cells and killer T cells to divide. Killer T cells kill infected cells in the body. Helper T cells also make suppressor T cells that inhibit the action of killer T cells and B cells when they are no longer needed.

33. Keeping Your Body Safe: Defense Systems CHECK YOUR NEIGHBOR How do vaccines protect us from disease? Explain your answer to your neighbor.

34. Keeping Your Body Safe: Defense Systems CHECK YOUR ANSWER Vaccines make use of the acquired immune system’s “memory.” They expose the body to antigens of a particular pathogen without introducing the pathogen itself. Vaccines contain dead or weakened pathogens or parts of pathogens that stimulate the immune response.

35. Keeping the Body Safe: Defense Systems Autoimmune diseases occur when a malfunction in the immune system causes it to attack certain body cells. Examples: • Type I diabetes • Multiple sclerosis • Lupus

36. Keeping the Body Safe: Defense Systems HIV—the virus that causes AIDS—attacks immune cells, particularly helper T cells. With the immune system compromised, many infections and cancers can overwhelm the body.

37. Technology: Transplanting Bone Marrow Bone marrow transplants allow patients to survive after aggressive cancer treatments. A patient may have his or her own stem cells harvested before cancer treatment or receive donor cells from another person. Replacing the damaged bone marrow stem cells allows the patient to continue to generate red and white blood cells and platelets after cancer treatment.

38. Science and Society: What Are the Odds? In the United States, heart disease is still the leading cause of death, followed by cancer and strokes.

39. Science and Society: The Placebo Effect Placebos may operate through the release of endorphins, natural opiates that prevent a patient from feeling pain, or from stress reduction, allowing the immune system to function more effectively. A patient’s expectations also affect the outcome.

40. Science and Society: AIDS CHECK YOUR NEIGHBOR Which of the following groups is acquiring AIDS at an increasingly high rate? • Women • East Asians • Eastern Europeans • Central Asians Explain your answer to your neighbor.

41. Science and Society: AIDS CHECK YOUR ANSWER The answer is all of these groups. Women, and people from East Asia, Central Asia, and Eastern Europe, are increasingly becoming infected with HIV.