1. U NIT 16 (C H. 22) G AS E XCHANGE & E XCRETION How do organisms: Obtain oxygen and eliminate carbon dioxide? (or vice versa…in plants?) Maintain osmotic balance? Excrete nitrogenous waste products? 300 Part 2

2. E XCRETION OF METABOLIC WASTE & M AINTENANCE OF O SMOTIC B ALANCE CH. 22.2

3. E XCRETION OF METABOLIC WASTE … IS DIFFERENT FROM THE ELIMINATION OF DIGESTIVE WASTES !

4. E XCRETION ♦ What is excretion? ♦ removal of wastes produced from metabolism of nutrients (& other non-useful materials) ♦ CO 2 ♦ excess water ♦ nitrogenous waste ♦ All metabolic wastes removed through excretory organs (nephridia, Malpighian tubules, kidneys) ♦ exception = CO 2, excreted with water vapor through lungs

5. E XCRETION ♦W♦Why must cellular wastes be removed? ♦c♦can be toxic ♦W♦Which life characteristic does excretion relate to? ♦h♦homeostasis

6. ♦m♦mostly from protein metabolism ♦&♦& some from nucleic acids ♦a♦amino groups quickly pick up H ♦t♦to become a mmonia ♦h♦highly toxic ♦m♦may be excreted directly or converted to less toxic forms ♦u♦urea ♦u♦uric acid N ITROGENOUS W ASTE

7. ♦a♦ammonia ♦e♦excreted by aquatic organisms ♦u♦urea ♦e♦excreted in small amount of water ♦♦ urine ♦u♦uric acid ♦i♦insoluble ♦e♦excreted as crystals ♦i♦in arid environments N ITROGENOUS W ASTES How is the production of urea/uric acid an adaptation to life on land/dry environments? H 2 O conservation

8. O SMOTIC B ALANCE ♦ concentration of dissolved particles in liquid inside & outside cell is the same (isotonic) ♦ What if the concentrations are different? ♦ hypotonic ♦ cytolysis ♦ hypertonic ♦ plasmolysis ♦ Adaptations for waste removal may also be responsible for maintaining osmotic balance Importance of H 2 O: reactions, part of blood, disperse heat

9. SALT WATER ORGANISMS ♦ excretion ♦ ammonia is soluble ♦ diffuses from (cells) into water ♦ osmotic balance ♦ naturally in balance ♦ no special adaptations needed

10. F RESH W ATER O RGANISMS ♦ excretion ♦ waste diffuses from (cells) into water ♦ osmotic balance ♦ not naturally in balance (hypotonic environment) ♦ Adaptations to help maintain? ♦ contractile vacuole ♦ ex. Paramecium Video of Paramecium--Contractile Vacuole

11. ♦ Planaria ♦ excretion of wastes & osmotic balance ♦ system of excretory canals & flame cells ♦ canals branch into excretory ducts ♦ open as pores on the surface F RESH W ATER O RGANISMS

12. L AND A NIMALS ♦ cannot diffuse ammonia ♦ must convert to urea or uric acid ♦ can safely build up in body fluids until excreted ♦ wastes transported by blood or tissue fluid ♦ system excretes N-wastes & is a factor in osmotic balance ♦ H 2 O conservation emphasized Uric acid

13. ♦ ammonia ♦ diffuses through skin ♦ into soil moisture ♦ urea ♦ eliminated through nephridia ♦ filtering organs LAND ANIMALS: EARTHWORM

14. ♦ Malpighian tubules ♦ filter blood ♦ reabsorb water ♦ uric acid enters intestine ♦ excreted thru anus ♦ Why is ammonia converted uric acid (crystals)? ♦ H 2 O conservation LAND ANIMALS: GRASSHOPPER

15. ♦ Habitat? ♦ desert ♦ Can survive without drinking H 2 O. ♦ How is this possible? ♦ gets water from food ♦ extremely efficient kidneys ♦ reabsorbs almost all water that passes through them ♦ excretes very concentrated urine L AND A NIMALS : Kangaroo RatKangaroo Rat

16. H UMAN E XCRETION ♦ Which parts of the human body carryout excretion? ♦ lungs ♦ CO 2 & H 2 O (vapor) ♦ skin ♦ H 2 O & salts ♦ = sweat ♦ urinary system ♦ urea, H 2 O, salts ♦ = urine

17. HUMAN EXCRETION ♦ What are the parts of the urinary system? ♦ kidneys (& associated blood vessels) ♦ main excretory organ ♦ ureters ♦ (urinary) bladder ♦ urethra

18. HUMAN EXCRETIONHUMAN EXCRETION: THE KIDNEY ♦m♦main excretory organ ♦3♦3 parts ♦o♦outer part ♦c♦cortex ♦i♦inner layer ♦m♦medulla ♦i♦inner collecting area ♦p♦pelvis

19. 5 STEPS TO HOW KIDNEYS WORK 1. blood w/ waste brought to kidneys from renal artery 2. blood is f iltered by nephrons (by diffusion) 3. wastes pass thru ureters to bladder as urine 4. clean blood sent back to body thru renal vein 5. bladder stores urine (until passes out of body thru urethra) 1 million nephrons per kidney!!! How Kidneys Work Video

20. ♦ What is a nephron? ♦ functional unit of the kidney ♦ responsible for filtration of waste from blood ♦ ~1 million nephrons per kidney!!! NEPHRON

21. NEPHRON: STRUCTURE ♦ nephron consists of: ♦ Bowman’s capsule ♦ cup-shaped ♦ surrounds glomerulus ♦ narrows into coiled tubule

22. NEPHRON: STRUCTURE ♦g♦glomerulus ♦m♦mass of capillaries in center of Bowman’s capsule that forms f rom branch of renal artery ♦c♦carries unfiltered “waste-filled” blood to nephron ♦a♦another arteriole loops away from glomerulus & divides into capillaries that surround t ubule

23. ♦ capillaries surround tubule ♦ merge to form venules & veins ♦ which merge to form renal vein which returns filtered blood back to body

25. PROCESSES IN THE NEPHRON ♦ filtration of blood/ urine production ♦ requires three distinct processes: 1. glomerular filtration 2. tubular reabsorption 3. tubular secretion ♦ excretion of urine

26. ♦ 1. filtration ♦ “waste-filled” blood brought to kidney by renal artery ♦ blood pressure forces plasma from blood in glomerulus into Bowman’s capsule of nephron ♦ this liquid = filtrate (water, urea, salts, glucose, amino acids & other dissolved materials) ♦ large proteins & blood cells do not enter PROCESSES IN THE NEPHRON

27. ♦2♦2. tubular reabsorption ♦f♦filtrate travels through nephron in tubule ♦n♦needed materials are reabsorbed into surrounding capillaries ♦e♦ex. most of water, salts, glucose, vitamins, etc. ♦b♦by active or passive transport ♦e♦excess materials remain in the collecting duct ♦w♦water, urea, salts ♦c♦concentrated fluid = urine tubul e. PROCESSES IN THE NEPHRON

28. ♦ 3. tubular secretion ♦ molecules present in blood in great excess (or natural poisons) may be removed from capillaries & transferred to tubules for excretion ♦ often by active transport ♦ ex. drugs such as antibiotics ♦ “clean” blood sent back to body through renal vein PROCESSES IN THE NEPHRON

29. ♦ excretion ♦ urine (urea, excess salt, small amount of water) leaves nephron & passes from collecting duct to renal pelvis ♦ leaves kidney via ureters ♦ to bladder where stored until once filled & urine is excreted through urethra (urination) How Kidneys Work Video PROCESSES IN THE NEPHRON

31. PROCESSES IN THE NEPHRON

32. PROCESSES IN THE NEPHRON

33. PROCESSES IN THE NEPHRON