Human Body Systems

1. Human Body Systems IB Chapter 6

2. Digestion • Why do we digest food? • Break down molecules to pass across the cell membrane.

3. Steps of Digestion • Ingestion: eat the food • Digestion: Chemical rxns that convert food to smaller and smaller particles • Absorption: Small molecules absorbed through cells and pass to blood stream • Transport: circulatory system delivers molecules to body cells

4. Molecules

5. Enzymes in Digestion • Enzymes lower activation energy and allow molecules to be broken down • Enzymes are molecule specific • In digestion, specifically aid hydrolysis reactions

6. Enzymes

7. Human digestive system • Mouth: breaks up food • Esophagus (oesophagus in IB): transport to stomach by peristalsis (muscle contractions) • Stomach: churns to mix food with enzymes • pepsin • Hydrochloric acid: creates proper pH for pepsin and helps break down • Mucus: lines stomach to prevent damage from acid

8. Human digestive system • Small Intestine: • Bile from liver and gall bladder • Trypsin, lipase, and amylase from pancreas • Absorbs most of the food • Inner wall is lined with villi • Contains lacteal and capillary bed • Increases surface area

9. Human digestive system • Large Intestine: Main function is absorption of water. • Contains bacteria (E. coli) that helps synthesize vitamin K and maintain healthy environment • Undigested food leaves as waste

10. Circulatory System • The Heart • Pulmonary side (Right side): capillary bed is in lungs, blood picks up oxygen and releases carbon dioxide • Systemic side (Left side): capillary bed is in body organs, blood picks up carbon dioxide and releases oxygen • Coronary arteries supply the heart with blood and oxygen

11. The Heart

12. Control of Heart Rate • Myogenic contractions: cardiac muscle contracts and reacts without nervous system signals

13. Control of Heart Rate • Controlled by Sinoatrial node (SA node): • Mass of tissue in atrium walls • Pace maker: controls atria • Also atrioventricular node (AV node): • Mass of tissue in right atrium • Contracts ventricles about .1 sec after SA fires

14. Control of Heart Rate • Chemicals can influence heart rate • Adrenaline: Causes SA node to fire more frequently

15. Circulatory System • Arteries: blood vessels taking blood away from the heart • Veins: collect blood from capillaries and return it to heart (Internal valves that act as backflow preventers) • Capillaries: found after arteries to distribute blood to certain areas

16. Circulatory System

17. Components of blood

18. Transport by Blood

19. Is deoxygenated blood blue? • No! • Oxygenated blood is bright red • Deoxygenated blood is dark red • Veins appear blue because light is diffused through skin • When skin is removed, can’t tell between veins and arteries

20. END of PART 1

21. Defense Against Disease • Germ Theory: Pathogens cause disease. • Pathogen: Any living organism or virus that is capable of causing a disease.

22. Bacteria • Bacteria are prokaryotic • Differ in biochemical pathways and reactions • Different structures

23. Antibiotics • Antibiotics: take advantage of these differences • Block cell’s ability to make protein • Block cell’s ability to make cell membrane or wall

24. Antibiotics • No effect on viruses • Insert their DNA into body cells and use our metabolism • Cannot block pathways without blocking all cell pathways and killing all cells.

25. Preventing Pathogens • Skin: Barrier to infection • Outer layer is dead and constantly being replaced • Bacteria cannot infect dead tissue • Cuts and open skin need to be treated

26. Preventing Pathogens • Stomach Acid: Acidic environment kills most of the ingested pathogens

27. Preventing Pathogens • Mucus: Blocks pathogens that enter through air • Sticky to trap pathogens • Contain lysozymes which chemically damage pathogens • Cilia surround mucus cells and move pathogens to trachea to cough out

28. Immune System • Phagocytic leucocytes: ingest pathogens • Macrophage: Ingests pathogens by amoeboid movement • Contain lysosomes which break them down

29. Immune System • Macrophage steps • Recognize whether cell is “self” or “non-self” • Based on glycoproteins in membrane • If non-self, it engulfs it and lysosomes digest it. • Non-specific response: engulfs anything that is foreign

30. Antibodies • Protein molecules that are produced in response to a specific pathogen • Antigens:proteins on the outer coat/membrane of pathogens • Each antibody is specific to each antigen

31. More on Antibodies • Y-shaped • Each end has a binding site that attaches to the antigen.

32. B-lymphocytes • Leucocyte that produces antibodies • Can only produce one kind of antibody

33. Typical Immune Response • Antigen is identified (virus) • B-lymphocyte is identified that will bind • B-lymph. Clones itself rapidly to increase # • B-lymphs begin producing antibodies • Antibodies circulate • Eliminate pathogen • Some B-lymphocytes remain for next time (memory cells)

34. HIV • Infects Helper T-cells • Communicate which cells need to undergo cloning for antibody production • When they die no antibodies are produced • AIDS: once they stop fighting infections • Usually die of secondary infections

35. Issues related to AIDS • Virus hides away for years • Virus mutates quickly • Association of AIDS to drug use and sexual activity • Initial reluctance for funding • Blood wasn’t tested before transfusions • Led to discrimination by employers, insurance, and education facilities

36. Respiratory System • Purpose: To provide the cells with Oxygen so they can undergo cell respiration

37. Respiratory system • Ventilation: Filling our lungs with air, then breathing that air out • Gas exchange: Diffusion of the gases into and out of the capillaries • Cell respiration: Breaking down glucose into ATP and CO2

38. Respiratory System • Why do we need one? • Gases cannot diffuse very far • Concentration of gases in the lungs encourages diffusion

39. Alveoli • Clusters at the ends of the bronchioles • Surrounded by capillary bed • Where gas exchange occurs

40. Alveoli

41. Mechanism of inspiration • Diaphragm and intercostal muscles contract • Pressure decreases and lung tissue increases in volume • Decrease in pressure inside (partial vaccuum) • Air comes in through mouth and nose

42. Breathing

43. Nervous System • Central Nervous System: Spinal cord and brain • Neurons (Neurones): cells that carry nerve impulse.

44. Peripheral Nervous System • Sensory and Motor nerves • Two categories: • Spinal nerves: emerge directly from spinal cord • Cranial nerves: nerves from the brainstem

45. Typical pathway • Stimulation: Transform a stimulus into an action potential • Interpretation: occurs in the brain • Chain of nerves that takes the action potential to the brain • Response: Pathway begins in the brain and travels down to the motor neurons

46. Nerve Impulse • Kind of like a flow of electrons down the neurons

47. Resting potential • State of being of a nerve that is ready to send an action potential • Active transport of Na+ and K+ in two different directions • Na+ out of axon • K+ into axon cytoplasm

48. Resting potential • Collection of ions leads to a net positive charge outside the axon and net negative inside • Sets up concentration gradient

49. Action Potential • Diffusion of Na+ back into the cell and K+ back out of the cell. • Moves “impulse” down the axon. • Once you start the potential it will self-propagate down the axon

50. Resting Action potential Resting