EXCRETION

1. EXCRETION • The process by which metabolic wastes and excess substances are removed from an organism. • Excretion also removes excess heat from a body which helps keep the body temperature constant. • Excretion helps maintain homeostasis.

2. Metabolic wastes are: • Carbon dioxide (CO2) • from cellular respiration • Water • from cellular respiration and dehydration synthesis • Nitrogen compounds (ammonia, urea, uric acid) • from the breakdown of amino acids • Mineral salts • built up during metabolism

3. ELIMINATION(defecation) • Removal of undigested or unabsorbed material in the form of feces from the digestive tract.

4. ADAPTATIONS IN THE FAB FIVE

5. EXCRETION IN PROTISTS Wastes diffuse out of the cell through the cell membrane into surrounding water Wastes include • Carbon dioxide • Mineral salts • Ammonia (is soluble in surrounding water) Water constantly diffuses into the cell by osmosis • Requires active transport to pump excess water out of the cell • Contractile vacuole fill with water • When full, they will inject water from the cell

6. PARAMECIUM CONTRACTILE VACUOLES

7. EXCRETION IN A HYDRA Wastes diffuse out of the cells into the surrounding water Wastes include: • Carbon dioxide • Mineral salts • Ammonia Water constantly diffuses into the cells by osmosis Water is pumped out by an unknown method of active transport • Contractile vacuoles have not been seen in hydras

8. CO2 THE HYDRA O2 ammonia Mineral salts endoderm Gastrovascular cavity ectoderm

9. EXCRETION IN EARTHWORMS Nephridia = the excretory organs of the earthworm • A pair of nephridia are in each section of the earthworm’s body Wastes from the body cells diffuse into the fluid of the body cavities • Wastes from the body fluid enters the nephridia at the nephrostrome • Fluid travels through the tubule loops and into the bladder • The bladder drains to the outside of the body through an external opening called a nephridiopore • Dilute solution called urine • Urine made up of water, mineral salts, ammonia, and urea

10. EXCRETION IN EARTHWORMS Wastes from the blood stream pass from the capillaries into the nephridium Useful substances (glucose and water) pass from the body fluid to the nephridium to the blood Carbon dioxide is excreted through the moist skin

11. EXCRETION IN EARTHWORMS

12. EXCRETION IN GRASSHOPPERS Malpighian tubules = excretory organs of grasshoppers and insects • The malpighian tubules are bathed directly by the blood in the open circulatory system • Wastes and water from the blood move into the tubules by diffusion and active transport • Wastes then pass into the intestines • Water and any useful materials are reabsorbed back into the body fluids from the digestive tract • Dry nitrogenous wastes (uric acid) pass out of the body through the anus with other digestive waste (feces)

13. EXCRETION IN GRASSHOPPERS

14. 4. SKIN LUNG LIVER KIDNEY

15. HUMAN URINARY SYSTEM 1. Renal artery 3. Cortex 2. Renal vein 4. Medulla 7. Adrenal gland 5. Pelvis 8. Kidney 9. Ureter 10. Urinary bladder 6. Ureter 11. Urethra

16. EXCRETION Definition: The process by which wastes and excess substances are removed from an organism.

17. Role of the Liver • DETOXIFICATION • SECRETION OF BILE • FORMATION OF UREA

18. DETOXIFICATION • removes harmful substances from the blood (bacteria, drugs, hormones) • changes harmful substances to less harmful forms • substances are returned to the blood and excreted through the kidneys • Cirrhosis – overloading of the body with toxins, the liver becomes overgrown with excess tissue and it decreases function, may eventually fail leading to death

19. DETOXIFICATION

20. Cirrhosis of the Liver Cirrhosis – overloading of the body with toxins, the liver becomes overgrown with excess tissue and it decreases function, may eventually fail leading to death

21. Secretion of bile • bile salts, cholesterol, hemoglobin molecule parts are secreted to the gallbladder (where they are temporarily stored) • secreted to the small intestine where it assists in lipid digestion • bile salts reabsorbed and returned to the liver • rest of materials pass to the large intestines are excreted with feces • Jaundice – if bile wastes are not excreted properly and the hemoglobin is reabsorbed, the skin takes on a yellowish color

22. Secretion of bile

23. Jaundice if bile wastes are not excreted properly and the hemoglobin is reabsorbed, the skin takes on a yellowish color

24. Formation of Urea • amino acids (from protein digestion) are broken down in the liver • each NH2 group changed into NH3 which is used to form urea • urea in the liver diffuses into the blood that flows to the kidneys and is excreted as urine

25. Formation of Urea

26. ADRENAL GLANDS KIDNEYS URETER INFERIOR VENA CAVA AORTA URINARY BLADDER URETHRA

27. Function • Kidneys (produce urine) • Remove cellular respiration waste from the blood • Regulate concentration of substances in body fluids • Ureter • Passage way from the kidneys to the bladder • Urinary bladder • Storage of urine • Urethra • Passage way for urine from the bladder to outside the body

28. Structure of the Kidneys • Three parts of the kidney • 1. Cortex – blood is filtered through the nephrons located here • 2. Medulla – made up of collecting ducts that send the filtrate (filtered material) to the pelvis • 3. Pelvis – urine drains from here into the ureter CORTEX 1. MEDULLA 2. PELVIS 3. RENAL VEIN 4. RENAL ARTERY 5. URETER 6.

29. NEPHRONS The filtering of wastes from the blood takes place in the nephrons. Part of the structure is in the cortex and part is in the medulla.

30. NEPHRONS • Glomerulus – tight ball of capillaries where blood is filtered • Bowman’s Capsule – collects filtrate that has been filtered from the blood • Renal Tubule – passes filtrate from Bowman’s Capsule to the collecting duct • Loop of Henle – a loop of renal tubule • Collecting duct – one collecting duct receives filtrate from many different nephrons and drains it from the medulla

31. The Major Functional Unit of the Kidney is the Nephron Collecting Tubule Bowman’s Capsule Collecting Duct Glomerulus Renal Artery Renal Vein Capillary network Loop of Henle

32. The Nephron 1. Bowman’s capsule 10. collecting tubule 2. arterioles 3. renal artery 4. glomerulus 9. collecting duct 5. capillary network 6. renal vein to pelvis 7. venule 8. Loop of Henle

33. URINE FORMATION • FILTRATION • REABSORPTION

34. URINE FORMATION • Filtration • Takes place in the glomerulus and the Bowman’s capsule Bowman’s capsule capillary water *molecules are small amino acids enough to pass through urea the capillary to wall saltsinto Bowman’s capsule *blood cells and proteins are too large to pass from the capillary to the Bowman’s capsule

35. Urine Formation II. Reabsorption While filtrate travels down the renal tubules, the volume of filtrate is reduced 99% of the water, all glucose and amino acids, and many salts are passed back into the blood Water is reabsorbed by osmosis Other materials are reabsorbed by active transport renal tubules capillary glucose water a. a. salts Filtrate left is highly concentrated (urine) Urine flows from the renal tubules to the collecting duct Urine passes from the kidneys into the ureters and on to the bladder

36. Control of kidney function • The kidneys are responsible for keeping homeostasis, which is achieved by regulating the volume and concentration of body fluids; which is controlled by selectively filtering and reabsorbing materials from the blood. The kidney has an auto-regulation mechanism • The rate of filtration and reabsorption responds to changes in blood pressure and the composition of the blood

37. Control of kidney function In other words; kidney function is controlled primarily by the composition of the blood.

38. The kidneys are also controlled by The nervous system and hormones • When cells in the hypothalamus (part of the brain) are in a hypertonic environment (cells are losing water), they stimulate thirst. • Changes in blood volume also stimulates receptors in the heart that in turn stimulate the release of certain hormones that affect the rates of reabsorption in the kidneys (therefore changing the blood volume)

39. Substances that crystallize are called kidney stones If kidneys fail – artificial kidney function through dialysis

40. Kidney Stones

41. Kidney Dialysis

42. Structure of the Skin HAIR PORE EPIDERMIS KERATIN NERVES SEBACEOUS GLAND DERMIS HAIR FOLLICLE SWEAT GLAND

43. Structure of the Skin Epidermis Tightly packed epithelia cells Deepest level made up of rapidly dividing cells As cells push up, they die off Produce keratin (tough, waterproofing protein) for protection of the dermis EPIDERMIS

44. Structure of the Skin Dermis Made of elastic, connective tissue Supports skin Contains blood vessels, lymph vessels, nerves, sense receptors, sebaceous glands (oil secretions), sweat glands (coiling tubes that open to pores), and hair follicles DERMIS

45. Structure of the Skin Adipose tissue A layer of fat Adipose tissue

46. Functions of the Skin • As a barrier • Keeps microorganisms out • Keeps water in • Removal of heat • Increased blood flow to the surface of the skin cools the blood • Sweat evaporates off the skin causing cooling • Keeps the body warm • Decreased blood flow to the skin keeps the core warm

47. The most important function of the skin (as an organ of excretion)is Removal of heat primarily by sweating