Immune System

1. Immune System Ch 43

2. Human Body has 3 lines of defense 1) Nonspecific defense – unspecialized, general defense against all • Ex. Skin, cilia, gastric juices, mucus 2) 2nd line of nonspecific defense • Phagocytes = WBC, engulf pathogens by phagocytosis (neutrophils) • Complement rxns – proteins, help phagocytes kill microbes • ex. interferons – released by cells to attack viruses • Inflammation – ex. histamine – releases phagocytes

3. 3) Immune response – v. specific • antigens = foreign invader, signal production of antibodies

4. Lymphocytes • = WBC, primary agent in the immune response • made in marrow, concentrate in lymph, thymus and spleen

5. Types of WBC 1) B cells– made in the bone marrow, binds to antigens (specific) • antibodies = proteins, specific to an antigen, video • Y shaped, bind to antigens, then phagocytes engulf • 5 classes called immunoglobins

6. plasma cells - B cells that release specific antibodies • memory cells - long lived B cells, respond to old invasions, immunity (10-17 days after primary invasion) – p846

7. 2) T cells – made in marrow but mature in the thymus • helps in differentiation between self and nonself cells, MHC judges self cells, if sees an invader it makes: • killer T cells - attacks foreign cells, causes them to lyse • helper T cells - makes more B and killer T cells • video

8. 2 types of immune system reactions – *p848 1) cell-mediated - T cells responds to any non self cell and bind 2) humoral or antibody mediated response - involves most cells by responding to antigens or pathogens in the blood • B cells then make memory cells for immunity

10. Disease treatment 1) use antibodies derived from bacteria 2) vaccines- weak pathogens, stimulate memory cells 3) ? autoimmune diseases – fights self cells, Lupus, MS 4) Immunodeficiency disease – major immune failure, SCID mice, HIV • HIV- CD4 T cells depleted, retrovirus – so DNA into host’s genome

11. Homeostasis Ch 44

12. Thermoregulation • = regulation of body temperature • Ectotherms: body heat from their environment, cold-blooded, ex. amphibians, fish • Endotherms : generate body heat, homeotherms or warm-blooded = maintain a constant temperature

13. Mechanisms for temp. regulation 1) Evaporation = losing water to cool the body 2) Warm by metabolism - muscles contract and metabolic activities generate heat, ex. shivering 3)Adjusting surface area to regulate temperature • Vasodilatation = increase blood flow to an area, heat lost • Vasoconstriction – decrease blood flow, reduces heat loss • also: hibernation, migrate, hair, feathers, blubber

14. Excretory System • = homeostasis by regulating water & removing bad wastes • Osmoregulation = absorb and excrete water and dissolved substances to maintain water balance • ex. Marine fish - water is lost by osmosis, so must constantly drink, rarely urinate, and secrete salts via gills

15. Some mechanisms: 1. Contractile vacuoles -pump water out, Paramecia 2. Malpighian tubules – tubes that empty into the digestive track, wastes are excreted, insects 3. Vertebrate kidney – filtering tubes called nephrons, collect waste, passes through ureters to the bladder for storage, urine excreted through the urethra

16. Path – p883 • Nephron contains the glomerulus which is a ball of capillaries surrounded by Bowman’s capsule • Blood from renal artery enters here, goes through proximal tubule where secretion and absorption occurs and returns via renal vein • To Loop of Henle : water and salt reabsorbed • To distal tubule: more secretion and reabsorbing • To collecting duct – excess salt and water out via urine in ureter

19. 3 processes of the Nephron: 1.Filtration- nonselective, small material in the blood, 1-2 L a day 2.Secretion- in tubules, selective, ex. ph 3. Reabsorption –proximal and distal tubules and loop of Henle, reabsorb most of the “good” material and water

20. Ridding of waste usually involves ridding of nitrogen, which can become toxic • Aquatic animals excrete ammonia directly into the water • Mammals convert NH3 to urea in their livers. Urea is less toxic and requires less water to excrete in the urine • Birds, insects, reptiles convert urea to uric acid = insoluble in water, solid. Need less water to excrete.

21. Hormones • Antidiuretic hormone (ADH) – increases the reabsorption of water • Aldosterone - increases reabsorption of water and Na+

22. Endocrine System Ch 45

23. Function: make hormones to maintain homeostasis • Hormone = chemical produced in one part of the body that affects cells elsewhere → transported via blood

24. Hypothalamus—monitors the external/internal conditions • - stimulates hormones via neurosecretory cells, link hypothalamus and the Pituitary gland (master gland), found a the base of the hypothalamus. • Posterior pituitary = makes ADH, oxytocin • Anterior pituitary = produces growth hormone, FSH, LH, TSH, endorphins • Thyroid → calcitonin (Ca++), thyroxin, metabolism control • Pineal – melatonin (circadian) • Adrenal → epinephrine, norepinephrin, fight/flight rxns • Thymus → T cells, immunity • Gonads → androgens, estrogens, sexual development/function

27. Regulation of blood glucose • common feedback loop • pancreas contains cells called islets of Langerhans, that makes alpha and beta cells,

28. Beta cells secrete insulin→ if blood glucose rises, beta cells secrete insulin→ insulin stimulates cells to absorb glucose→ cells convert glucose to glycogen or fat → glucose concentration decreases • Alpha cells secrete glucagon→ if blood glucose drops, alpha cells secrete glucagon → glucagon stimulates the liver to release glucose (breaks down glycogen)