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Immune System

Ch 43

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Human Body has 3 lines of defense 1) Nonspecific defense – unspecialized, general defense against all Ex. Skin, cilia, gastric juices, mucus2) 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

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

of antibodies

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

spleen

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Types of WBC1) 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

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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

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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

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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

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Disease treatment

1) use antibodies derived from bacteria2) vaccines- weak pathogens, stimulate memory cells 3) ? autoimmune diseases – fights self cells, Lupus,

MS4) Immunodeficiency disease – major immune failure,

SCID mice, HIV HIV- CD4 T cells depleted, retrovirus – so DNA into

host’s genome

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Homeostasis

Ch 44

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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

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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

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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

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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

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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

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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

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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.

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Hormones

Antidiuretic hormone (ADH) – increases the reabsorption of water

Aldosterone - increases reabsorption of water and Na+

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Endocrine System

Ch 45

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Function: make hormones to maintain homeostasis

Hormone = chemical produced in one part of the body that affects cells elsewhere → transported via blood

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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

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Regulation of blood glucose common feedback loop pancreas contains cells called islets of Langerhans, that

makes alpha and beta cells,

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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)