2 categories of lymphocytes 1 T Cells Lymphocytes that are responsible for cellular immunity The original T cells are programmed in the thymus gland They then travel to and wait in lymph tissue only reproducing when needed 2 B Cells lymphocytes that are responsible for humoral immunity They are originally programmed in the bones Then wait in lymph tissue until activated to produce antibodies Cellular immunity 2 Helper T s After antigen presentation Helper T cells activate and sensitize other T cells to that antigen These T cells reproduce several types of cells 1 Cytotoxic killer T s a type which goes out and attaches to and chemically bombards the play a central role since they release chemicals which stimulate the antigen they also secrete macrophage activating chemicals proliferation reproduction of both T and B cells so without Helper T s there is no immune response the infection recurs they can initiate a swifter second response as in immunity occurs remain in the lymph node programmed to recognize the antigen such that if slow down or suppress the B and T activity 3 Regulatory T s 4 Memory T s Humoral immunity In this case cells don t go out and attack the invader instead they produce secrete antibodies which circulate in body fluids humors So the antibodies go out and neutralize the antigens When B cells are activated by a Helper T they enlarge and divide into 1 Plasma cells 2 Memory B s defeat the same disease again which produce secrete the antibodies for 4 5 days then dies same story as Memory T s Memory T ad B cells wait in lymph nodes to Immune system Problems Hypersensitivity compromised immune system an immune response intense enough to cause discomfort or even tissue damage This response is an over reaction to an antigen allergen which is not harmful in the first place We also call hypersensitivity an allergy and the antigen an allergen Immunodeficiencies can be congenital born with it or acquired e g Hodgkin s disease cancer of B cells AIDS acquired immune Deficiency Syndrome which is caused by the HIV virus which targets Helper T s and thereby depresses all immunity Autoimmune Diseases foreign antigens thus our own tissues are destroyed includes rheumatoid arthritis lupus multiple sclerosis type 1 diabetes grave s disease etc Something causes the body to fail to distinguish between self and The Urinary System Components 2 kidneys 2 ureters 1 urinary bladder 1 urethra Primary function is homeostasis of both the composition and the volume of blood This is accomplished by removing most of the water and solutes from the blood and then selectively restoring them Unneeded H2O ions solutes and toxins are then excreted in the form of urine Other Functions 1 Regulates blood pressure by producing a hormone enzyme renin Causes water retention increased blood volume and vasoconstriction constricts blood vessels 2 Producing erythropoietin which stimulates erythropoiesis 3 Regulates blood pH acidity 4 Activates Vitamin D Nephron the functional unit of a kidney There are over 1 million of these blood processing units which filter blood and then selectively reabsorb the filtrate or allow it to become urine urine is what is not reabsorbed A nephron consists of a renal tubule enclosing a capillary network called a glomerulus The end of the renal tubule expands and encloses the glomerulus and is called the glomerular capsule o Collectively the glomerulus and it s capsule are called a renal corpuscle The capillaries of the glomerulus are fenestrated very porous These pores allow virtually all the blood s plasma except large proteins to leave the capillaries and filter into the glomerular capsule The visceral layer of the glomerular capsule the layer touching the glomerulus is composed of branching octopus like epithelial cells called podocytes The arms of the podocytes wrap around the fenestrated capillaries leaving openings called filtration slits they control the opening to the pores in the capillaries Physiology The work of the urinary system is done by nephrons all the other structures are simply for storage or passageway The system filters about 45 gallons of blood day The plasma is filtered removed and returned 60 times a day 3 Steps in Urine Formation 1 Glomerular Filtration The plasma and solutes are forced out of the glomerular capillaries by hydrostatic pressure blood pressure This essentially non selective process involves the plasma being forced through A The fenestrated capillary endothelium B A basement membrane C The filtration slits left by the podocytes of the visceral glomerular capsule The pressures involved in glomerular filtration are A Glomerular blood hydrostatic pressure GHP Blood pressure entering glomerulus This is kept high because the afferent arteriole incoming vessel is much bigger than the efferent arteriole This pressure is about 60mm Hg mercury and forces plasma into the glomerular capsule And there are 2 opposing forces B Capsular hydrostatic pressure CHP Resistance due to fluids already in the glomerular capsule Amounts to 20mm Hg C Blood osmotic pressure BOP remember osmosis is diffusion of water through a permeable membrane from a dilute area toward a more concentrated one Since the blood remaining in the glomerulus is more concentrated than the filtrate the water tries to move back into the glomerular capillaries creating a resistant pressure of about 30mm Hg N F P Net Filtration Pressure the net result of the pressures NFP GHP CHP BOP 60mm 20mm 30mm 10mm It is important how they cancel each other out leaving little pressure for filtering If filtration stops toxins are left in the blood which is deadly renal failure can result from a drop in blood pressure GFR Glomerular Filtration Rate the amount of filtrate flowing out of all the renal corpuscles of both kidneys per minute Normal 125ml min 180 L 48 gallons of filtrate day 99 of this filtrate is reabsorbed back into the peritubular capillaries leaving 1 5 liters of urine day The return of filtrate to the blood stream is called Tubular reabsorption 2 Tubular Reabsorption Reabsorption occurs both passively diffusion and actively active as in requiring ATP and a carrier mechanism from the tubule back into the blood stream Passive reabsorption is essentially diffusion of water and small solutes ions 80 of H2O in the filtrate diffuses back into the peritubular capillaries we can increase H2O reabsorption by ADH antidiuretic hormone which increases the permeability i e porosity of the distal end
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