1. Excretion What is the difference between Excretion and Elimination?

2. Elimination of unabsorbed and undigested food in the form of feces. –These materials have never entered the body cells, therefore they are NOT metabolic waste.

3. Metabolic Waste: CO 2, water (respiration) Nitrogen Compounds: ammonia, urea, uric acid, (breakdown amino acid) Mineral salts: sodium chloride, potassium sulfate (metabolism) All of these waste products are poisonous in excess.

4. Excretion in Protists Diffusion through cell membrane into surrounding water Waste: CO 2, Mineral Salt, ammonia*

5. Ammonia: chief nitrogenous waste of microorganisms poisonous to cells, but soluble in water excreted as waste if water is present to wash it away

6. Excretion in Hydra Surface Area surrounded by water! Diffusion through cell membrane of each cell into surrounding water.

7. Excretion in Earthworm Most of cells are not in contact with surroundings: need specialized excretory organs Nephridia: –Structures found in pairs: one on each side –In most of segments, and extends slightly into next segment.

8. Nephridia of Worm 1) Metabolic wastes and nutrients in body fluid 2) Body fluid enters the nephristome (funnel shaped opening) 3) Cilia move the fluid through funnel into nephridium 4) Nephridium loops and widens into bladder 5) Bladder drains to outside of body through Nephridiopore

9. Exchange going on! Capillaries reabsorb nutrients that entered nephridia

10. Worm Pee water mineral salts ammonia urea

11. CO 2 Excretion Across Skin

12. Worm X-Section Nephridium Nephridiopore

14. Excretion in Grasshoppers Excretory organs of grasshoppers and other insects: Malpighian tubules

15. Grasshopper 1. Wastes and nutrients enter the Malpighian Tubules by diffusion and active transport. 2. Material is passed into intestine 3. Nutrients are reabsorbed from the tubules and digestive tract and returned to body fluid. 4. Dry nitrogenous waste product, uric acid, feces pass out through anus.

16. Grasshopper Urine: –Solid Uric acid crystal –Out the anus –Least poisonous nitrogenous waste –Not water soluble (saves water)

17. Human Excretory System Metabolic wastes: CO 2 Urea Water Mineral Salts

18. Organs of Excretion 1.Lungs 2.Kidneys 3.Liver 4.Skin

19. The Liver Regulates the makeup of body fluid Detoxification: Liver detoxifies the blood Removes harmful substances: bacteria, certain drugs, hormones, from the blood Liver changes these substances into less harmful ones Inactive forms are returned to the blood and excreted via the kidneys

20. Overworked liver…. Alcohol causes Cirrhosis. –liver becomes overgrown with excess tissue –excess tissue cuts down blood flow –limits amount of detoxification it can perform –lead to death

21. The Liver Bile is made by the liver. –Contains bile salts, cholesterol, part of hemoglobin (worn out RBC). –Some of these products are metabolic waste.

22. Bile Cycle Bile collects in gallbladder. Passes into small intestine. Emulsifies of fats Bile salts are reabsorbed from small intestine into the blood Return to liver (recycling!) The rest of bile excreted through large intestine

23. Liver not working right… Jaundice: –when bile is NOT excreted properly. Reabsorbed hemoglobin fragments in blood cause skin to yellow.

25. Formation of Urea Amino acids are the breakdown products of proteins. We can not store excess protein. Breakdown occurs in the liver.

26. From each amino acid: The amino group (NH 2 ) is changed to Ammonia (NH 3 ), then to Urea (much less harmful). Urea diffuses into blood stream to the kidneys. Kidneys filter the urea and excrete as urine. Remainder of amino acid is changed to either: pyruvic acid, glycogen, or fat.

27. Urinary System Kidneys (2) Bladder Urethra

28. Kidneys: Bean shaped Located in posterior aspect of abdomen, just below the diaphragm. Functions: –Remove waste of cellular metabolism from the blood –Regulate the concentrations of the substances found in body fluids including water, salts –Maintain homeostasis

29. Structure of Kidneys Cortex: –outer part –Blood is filtered Medulla: – middle part –Made of tubes called collecting ducts –Carry filtered substances & filtrate to pelvis Pelvis: inner region –Cavity connected to the ureter –Urine formed from filtrate drains from pelvis into ureter

30. Nephrons –Kidney contains1.25 million nephrons –Filters waste from the blood –Part is in cortex, remainder is in medulla

31. Nephron

32. Parts of Nephron 1. Glomerulus: a group of capillaries that form a tight ball. 2. Bowman’s capsule: a double walled cup shaped structure surrounding the glomerulus

33. Filtration at Bowman’s Capsule Pressure pushes out “filtrate” Large substances (Proteins, cells, etc) do not enter Bowman’s capsule Filtrate includes: water, urea, glucose, amino acids, and various salts (like plasma! Just without the protein) Filtrate moves in Proximal Renal Tubule

34. Parts of Nephron 3. Proximal Renal Tubule: NaCl,H2O,Glucose, Potassium Reabsorption

35. Parts of Nephron 4. Loop of Henle: middle section that forms a long loop Water reabsorption with help of salt pumping Extends into the medulla region of Kidney Filtrate enters distal renal tubule

36. Parts of Nephron 5. Distal Convoluted Tubule H 2 O and Sodium reabsorption

37. Parts of Nephron 6. Collecting Duct Some urea reabsorption More H2O reabsorption Many collecting ducts fuse Urine exits out Ureter of Kidney Site of ADH action

38. Kidney Threshold Level If the concentration of a substance in the blood is greater than a certain level: it is not reabsorbed. The excess remains in the Urine

39. Imbalance in Homeostasis Blood sugar level of a person who has diabetes is so high that not all the glucose in the filtrate can return to the blood. Glucose in the Urine.

40. Urine: The fluid remaining in the tubules: water, urea, various salts Substances that crystallize out of the Urine: kidney stones Dialysis

41. Ureters Bring urine to urinary bladder Urine exits through urethra

42. Lungs: Lungs are considered part of the excretory system because they get rid of C02 and water (vapor)

43. Skin Excretes small amount of urea and salts in sweat

44. Skin Structure: Two Layers: 1.Epidermis 2.Dermis

45. Epidermis: outer layer Tightly packed epithelial cells. Deepest portion is rapidly dividing. As they push farther and farther from Dermis, they received less and less nourishment. Before dying, they produce Keratin: tough water proof protein Wears away, replaced by new cells. Protects Dermis.

46. Dermis Made of elastic connective tissue Binds to the muscle and bone beneath it. Contains: blood vessels, lymph vessels, nerves, sense receptors, sebaceous glands, sweat glands, hair follicles.

47. Sebaceous Glands Produce oily secretions that provide a protective coating to the skin and hair keeping them soft and pliable

48. Sweat Glands Made of coiled tubes that open to the surface through pores. Sweat is released through these pores

49. Subcutaneous Layer Adipose ( fat-storing) Cells

50. Heat Loss: Blood vessels in the skin open wider Increases the blood flow through the skin’s capillaries (flush) Allows more heat to be given off to the air Sweat begins to evaporate: cooling the body

51. Heat Retained: blood vessels in the skin narrow body sweats less

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