Circulatory System

1. Circulatory System

2. Circulatory System

3. Blood Summary • Cells (called formed elements) • Thrombocytes (platelets) • No nucleus. Fragments of red bone marrow cells • Function in clotting of blood

4. Blood Clotting • Blood vessel wall broken • Platelets stick to each other and to break. Release clotting factors.

5. Blood Clotting • Protein called prothrombin converted to thrombin, which causes fibrinogen in plasma to become fibrin (protein threads) • These threads bind together platelets and blood cells to make clot.

6. How Phagocytic WBCs work • Damage to tissues • Mast cells release histamine • Causes blood vessels to dilate • Increases permeability of capillaries.

7. How Phagocytic WBCs work • Neutrophils and monocytes stick to lining of capillary • Squeeze through wall into tissue • Locate and digest invading cells.

8. Excretory System

9. Excretory System • Quick review through the animal phyla: • Platyhelminthes: Flame cells in protonephridia • Draw in body fluids using cilia • Tubule reabsorbs some materials as fluids flow to excretory pores.

10. Excretory System • Quick review through the animal phyla: • Annelida: Nephridia. Body fluid forced into tubules under pressure • Some materials (salts) reabsorbed on way to pore.

11. Excretory System • Quick review through the animal phyla: • Insects: Malphigian tubules (extensions of gut) • Materials secreted into tubules by cells in walls • Tubules empty into hindgut • Some materials reabsorbed by hindgut on way out.

12. Excretory System • Here we emphasize human. Rat seen in lab.

13. Excretory System Functions • 1) Removal of wastes or other unwanted materials from body • water, salts • nitrogenous wastes (urea, ammonia, uric acid) • carbon dioxide • heavy metals (Pb, Cd, Hg) • 2) Balance water and dissolved materials in body tissues: osmoregulation.

14. Nitrogenous Wastes • Generated when amino acids converted to other molecules in body (deamination) • Also when nitrogenous bases of nucleic acids converted to other molecules.

15. Nitrogenous Wastes • What formed? • 1) Ammonia. Toxic, so must be kept highly diluted. Feasible only for aquatic animals.

16. Nitrogenous Wastes • What formed? • 2) Urea. Much less toxic. Soluble in water, so must be eliminated using water (in urine).

17. Nitrogenous Wastes • What formed? • 3) Uric acid. Low toxicity, not very soluble in water. Little water used to eliminate it. • BUT, formation complex and uses much energy.

18. Pretending to be Nitrogenous Wastes • Uric acid: white material in bird droppings and lizard poop

19. Excretion • Human organs involved: • 1) skin: sweat glands excrete water, salts (Na, K, Ca), some urea.

20. Excretion • Human organs involved: • 2) lungs: excrete carbon dioxide, water (up to 1 liter per night), and.............alcohol.

21. Excretion • Human organs involved: • 3) liver: bile pigments get rid of rbc breakdown products • 4) large intestine: some salts and metals enter and join feces.

22. Excretion • Human organs involved: • 5) kidneys: form urine. Regulate water balance and remove urea (nitrogenous waste) and other waste materials.

23. Urinary Tract • Renal artery and vein: Blood to/from kidney • Kidneys: one on each side • Ureter: duct from kidney to bladder.

24. Urinary Tract • Urinary bladder (expandable muscular bag): urine storage • Urethra: duct from bladder to opening • Female: Urethral opening. Male: Urogenital opening (both urine and semen pass through).

25. Kidney anatomy • Renal capsule: connective tissue sheath • Cortex: outer region • Medulla: inner region • Renal pelvis: leads to ureter.

26. Kidney anatomy • Functional unit: nephron • About 1 million per kidney • Found mostly in renal cortex, some extend into medulla.

27. Nephron structure • Arterioles enter/leave Bowman’s capsule • Glomerulus: capillary bed inside capsule

28. Nephron structure • Proximal convoluted tubule: close to capsule • Loop of Henle: constricted portion • Distal convoluted tubule: far from capsule

29. Nephron structure • Peritubule capillaries: bring blood close to tubules again • Collecting duct: carries final product (urine) to ureter.

30. Kidney function • Step 1: Filtration • Step 2: Reabsorption • Step 3: Secretion • Step 4: Excretion.

31. Kidney function • Step 1: Filtration • High pressure blood enters afferent arteriole • At glomerulus in renal corpuscle, plasma leaks into Bowman’s capsule as filtrate • Filtered blood leaves by efferent arteriole.

32. Kidney function • Step 1: Filtration • Filtrate passes to convoluted tubule • Contains: water, urea, salts, glucose, amino acids, etc. Everything in blood except formed elements and plasma proteins.

33. Kidney function • Step 2: Tubular reabsorption • What’s reabsorbed? • water (65%), by Loop of Henle and distal convoluted tubule • NaCl (65%), by Loop of Henle • glucose (100%): proximal tubule • most amino acids: proximal tubule • Most urea stays in tubule.

34. Kidney function • Step 3: Tubular secretion • Active transport of materials into collecting tubules. • Some toxic molecules, some medicines (ex, penicillin) • H+ secreted to maintain blood pH (urine slightly acidic).

35. Kidney function • Step 4: Excretion • Collecting duct to renal pelvis to ureter

36. Kidney function • Step 4: Excretion • To bladder, where stored (up to 1 liter) • Internal urethral sphincter (smooth muscle) • External urethral sphincter (skeletal muscle: under voluntary control in adults) • Contraction of bladder and relaxation of sphincters allows urination.

37. Busy kidneys • Body has about 5 liters blood • Kidneys filter 2000 liters of blood per day • 180 liters of filtrate produced • 1-2 liters of urine made per day

38. Kidney function • Summary: Urine contains water, salts, urea, H+ • How balance body water content? • Hormone called antidiuretic hormone (ADH). Controls water reabsorption in convoluted tubules and Loop of Henle.

39. Problems with the system • Kidney stones: material in urine crystallizes. • If large, has hard time passing down ureter and through urethra. Painful (stretching of ureter)! • Some women say worse than childbirth....

40. Problems with the system • Can be broken up with ultrasound so it passes more easily. Can be removed surgically. • Causes: heredity, infection, diet, dehydration, etc.

41. Problems with the system • Drink plenty of water! Stone removed from bladder of Afghan boy

42. Problems with the system • Diabetes • diabetes insipidus: not enough antidiuretic hormone produced • water not reabsorbed by nephrons. Lots of dilute urine made.

43. Problems with the system • Diabetes • diabetes mellitus (sugar diabetes) • actually is problem with pancreas function or liver function low insulin production, or liver not responsive to insulin, or combination • results in high glucose level in blood • kidneys adjust by not reabsorbing much glucose from filtrate (lots glucose in urine) • may result in kidney failure, blindness, heart disease, etc.

44. Problems with the system • Kidney failure • transplants: from cadavers or live donors • dialysis: using machine to artificially filter blood