Animal Structure & Function

1. Animal Structure & Function Chapters 40-49

2. Levels of Organization • Molecules • Cells • Tissues • Organs • Organ Systems • Organisms

3. Tissue Types • Epithelial: covers outside of body and lines organs and body cavities • Cuboidal • Columnar • Squamous • Simple • stratified

4. More… • Connective: bind and support other tissues: • Collagen: most abundant protein in animals • Adipose: fat • Tendons (muscle to bone) and ligaments • Cartilage: flexibility and cushion • Bone: osteoblasts and osteoclasts • Blood: RBCs and WBCs

5. More… • Nervous: senses stimuli and transmits signals from one part of animal to another • Neurons • Muscle: long cells called muscle fibers that contract and relax • Skeletal • Cardiac • Smooth

7. Homeostasis • “steady state” stable internal environment • Positive feedback: a change in some variable that triggers mechanisms that amplify the change • Negative feedback: a change in a variable triggers mechanisms that counteract further change in the same direction

8. Homeostasis and Glucose • Pancreas releases insulin to lower blood sugar • All cells have insulin receptors • Pancreas releases glucagon to raise blood sugar • Liver has glucagon receptors to allow glucagon to break down stored glycogen

10. Mammalian digestion • Peristalsis: muscular contractions that push food through digestive system • Alimentary canal: mouth, throat, esophagus, stomach, small intestine, large intestine, anus • Accessory organs: liver, pancreas, gall bladder, salivary glands

12. Follow the food! • Oral cavity: salivary glands release amylase to break down starch • Toungue and teeth mechanical digestion • Pharynx: throat connects mouth to esophagus • Esophagus: muscular tube to transport food to stomach • Epliglottis: flap covers trachea (windpipe)

13. Keep going… • Stomach: digestive juice of HCl (pH = 2) • Pepsin: breaks down proteins into small polypeptides • Small intestine: 6 meters long! • Pancreatic amylases break down small polysaccharides into monosaccharides • Trypsin, chymotrypsin: break down polypeptides into even smaller polypeptides • Aminopeptidase, carboxypeptidase: break down polypeptides into amino acids

14. Almost to the end! • Small intestine: • Nucleases: break down DNA and RNA into nucleotides • Bile salts: break down fats • Lipases: break down fats further to components (glycerol, fatty acids) • Microvilli: absorb all nutrients • Large intestine (colon): reclaim water and condense feces and store in rectum • Anus: exit for wastes

16. Circulatory systems • Open: blood bathes the organs directly • Closed: blood is confined to blood vessels

17. Heart • Atria: top chambers receive blood • Ventricles: bottom chambers pump blood • Aorta: major artery out of heart • Vena cava: major vein back to heart • Pulmonary arteries/veins: lead to and from lungs

18. Blood Flow • oxygen poor blood from body, Vena cava, right atrium, tricuspid valve, right ventricle, pulmonary valve, pulmonary artery, lung, pulmonary vein, left atrium, bicuspid valve, left ventricle, aortic valve, aorta, oxygen rich blood to body

20. Blood vessels • Arteries: high blood pressure • Arterioles • Veins: low blood pressure • Venules • Capillaries: tiny one cell thick vessels for gas and nutrient exchange

22. Cardiac cycle • Systole: contraction phase • “asystole” – heart is not contracting (dead) • Diastole: relaxation phase

23. Blood • 55% plasma: water, ions, proteins, nutrients, waste, gases, hormones • 45% cells: erythrocytes (RBC), leukocytes (WBC), and platelets (blood clotting)

25. Mammalian Respiratory System • Oral/nasal cavity • Pharynx – throat • Larynx – voice box • Trachea – windpipe • Bronchus – left/right tube into lungs • Bronchioles – branching tubes • Alveoli – sacs for gas exchange, connect to capillaries

27. Breathing • Negative pressure breathing in mammals • Diaphragm: muscle that pulls bottom of chest cavity • Inhalation: diaphragm contracts, chest cavity enlarges, air pressure in lungs drops, air rushes in • Exhalation: diaphragm relaxes, chest cavity gets smaller, air pressure in lungs increases, air gets pushed out

29. Gas transport • Hemoglobin: transports oxygen and to a limited extent carbon dioxide • Bicarbonate ions: transports majority of carbon dioxide

30. Nonspecific: Skin Mucous membranes Secretions Phagocytic WBC Antimicrobial proteins Inflammation Specific: Lymphocytes B-cells T-cells Antibodies Immune System Overview

31. Immune cells • Neutrophils: nonspecific engulfers (phagocytes) • Macrophages: same as above • Eosinophils: defend against parasites • Natural killer: destroy virus infected cells

33. Inflammatory Response • Arteries dilate, blood supply to wound increases (heat, swelling) • Histamines are responsible for inflammation • Prostaglandins also vasodilate

35. Specific response • B cells and T cells have membrane receptors specific for a certain antigen (foreign substance) • When an antigen is recognized by a certain lymphocyte, an immune response is initiated

37. Clonal Selection • Once an antigen is recognized, the specific lymphocyte is activated and millions of clones are made to fight off the invader • Primary immune response: 10-17 days to recognize antigen and generate maximum response • Shorter second exposure to same antigen due to memory cells

39. More… • Secondary immune response: the second exposure to same antigen • Faster response (2-7 days) • Greater magnitude • More prolonged response

40. Lymphocyte development • B-cells mature in bone marrow • T-cells mature in thymus • Taught to recognize self • If attacks self, induced to go through programmed cell death (apoptosis)

41. MHC and T cells • MHC are surface proteins on our body cells that mark self • MHC I: found on all cells • MHC II: found on macrophages, B cells, activated T cells, thymus cells • MHCs present antigens on cell surface • Cytotoxic (killer) T cells recognize MHC I and thus kill body cells infected with virus (CD8/MHC I) • Helper T cells recognize MHC II and thus take cues from other immune cells to help activate response (CD4, protein that recognizes MHC II)

43. T cells • Cytotoxic T cells use CD8 to bind to MHC I of an infected body cell • Release perforin to puncture holes in membrane killing cell • Helper T cells use CD4 to bind to MHC II of an APC and then becomes “middle cell” • Activates B cells to proliferate and release antibodies

44. Antibody structure and function • Made of 2 heavy chains and two light chains in shape of Y • The tips of Y have variable regions • Small changes in gene expression lead to millions of possible variable regions each specific to a different antigen • Antibodies get mass produced by activated B cells and secreted into blood

46. Antibody function • Binds to antigen and blocks activity (neutralization) • Binds to antigen in more than one place and results in clumping (agglutination) • Binds to antigen and activates complement system (immune proteins that can poke holes in antigen and destroy it

48. Immunity • Active: conferred upon recovery from infection or immunizations (vaccines) • Passive: pregnancy and breast feeding

49. Problems • Allergies: mast cells overreact to allergens, release histamine, leads to inflammation • Autoimmune diseases: immune system attacks self (lupus, rheumatoid arthritis, multiple sclerosis) • Immunodeficiency diseases: immune system is weakened and unable to fight off routine infections (HIV)

50. Temperature • Endotherms: derives most or all of body heat from metabolism • Ectotherms: derives heat from external environment • Vasodilation: more blood flow, more heat loss • Vasoconstriction: less blood flow, less heat loss