1. HUMAN EXCRETORY
SYSTEM

2. EXCRETION
The removal of cellular wastes (Metabolic Waste) from the body.

3. Major Metabolic Wastes
Carbon Dioxide (CO2)
Produced as a result of cellular respiration.
Water (H2O)
An end product of many chemical reactions including cell respiration and dehydration synthesis.
Nitrogen Wastes
An end product of the breakdown of protein.
Ammonia – most toxic
Urea – mildly toxic
Salts
Produced as a result of chemical reaction

4. Main Organs of Excretion

5. Organs of Excretion: Lungs  Removes carbon dioxide and water
Liver  Urea is formed which resulted from break down of amino acids and breakdown of RBCs
Skin  Sweat Glands -Removes excess water and salts, urea and heat.
Kidneys  Remove water, salts and urea

6. Liver
Removal and detoxification of harmful substances from the blood (bacteria, drugs, hormones, alcohol)

7. Liver
Removal of broken down RBC’s

8. Liver
Deamination
Ammonia (NH3) is formed by the breakdown of amino acids

9. Liver
ammonia is converted into a less toxic substance, urea, which enters the bloodstream to the kidneys for excretion

10. The Skin

11. The Skin Sweat comes out of pores in your skin.
Mixture of three metabolic wastes:
Water
Salts
Urea

12. The Skin As you sweat, your body accomplishes two things:
1) It has a cooling effect on the body.
2) metabolic wastes are excreted  

13. The Lungs

14. The Lungs
Cellular respiration produces carbon dioxide as a waste product. 

15. The Kidneys The major excretory organ in the human body
Filtering of the blood helps regulate its chemical composition. 
Water soluble materials are absorbed from blood by diffusion in the kidney.
Needed materials are reabsorbed
Wastes: Urea, salts and excess water are excreted

16. Organs of the Urinary System

17. Organs of the Urinary System
Kidneys
Two kidneys are located on either side of the spinal column near lower back.
Ureter
Two tubes that leaves each kidney carrying urine to the urinary bladder.
Urinary Bladder
Muscular sac that stores liquid wastes before excretion.
Urethra
Carries the urine from the bladder to the outside of the body – controlled by a sphincter muscle.

18. The Functions of the Kidney
1. Filtration of blood:
water, urea, amino acids, salts, glucose pass out of the blood into the Kidneys by diffusion
Proteins (enzymes, hormones, antibodies) and blood cells remain behind in the blood

19. The Functions of the Kidney
2. Reabsorption:
Important substances are returned to the blood (water, glucose, amino acids, salts) by active transport and diffusion

20. The Functions of the Kidney
3. Formation of urine: (urea, excess water, salts)

21. The Kidneys There are three major areas in the kidney
Outer portion is the cortex
Middle portion is the medulla
Inner portion is the renal pelvis

22. The Kidneys Bean-shaped about 10 cm long each. Nephron:
The functional unit of the kidney
Renal artery and Renal vein leading to and from the kidneys

23. Parts of the Nephron Glomerulus Bowman’s Capsule Ball of capillaries
surrounded by
the Bowman’s Capsule.
Bowman’s Capsule
Cup-shaped structure
that filters the materials out
of the blood.

24. Parts of the Nephron

25. Filtration of the Blood
Filtration occurs as blood pressure forces fluid from the blood in the glomerulus into the lumen of Bowman’s capsule
Filtration of small molecules is nonselective
RBC’s and Protein don’t get filtered
The filtrate contains salts, glucose, and nitrogen wastes

26. Pathway of the Filtrate
From Bowman’s capsule, the filtrate passes through three regions of the nephron: the proximal tubule, the loop of Henle, and the distal tubule
Fluid from several nephrons flows into a collecting duct, all of which lead to the renal pelvis, which is drained by the ureter

27. From Blood Filtrate to Urine: A Closer Look
Proximal Tubule
Reabsorption of Salts , Glucose . Nutrients
Takes place by Active and Passive Trasport

28. Distal Tubule
Regulates the K+ and NaCl concentrations of body fluids
Helps in pH regulation

29. Collecting Duct
The collecting duct carries filtrate through the medulla to the renal pelvis
This is where the filtrate becomes more concentrated.

30. Flow through Kidney:
Renal Artery Glomerulus Bowman’s Capsule Loop of Henle Collecting Tubule( Duct ) Ureter Bladder Urethra

31. Malfunctions of the
Urinary System

32. Malfunctions of the Excretory System
Urinary Tract Infection (UTI)-
Bacterial infection that can affect any part of the urinary system.
Nephritis:
Bacterial infection of the kidney.

33. Malfunctions of the Excretory System
Kidney Stones –
Caused by accumulation of a crystallized solid such as calcium
Treatment:
Sound waves
Surgery

35. Gout:
Disease associated with abnormal uric acid production and excretion - causing deposits in the joints (toes) resulting in severe pain.

36. Gout:

37. Kidney (Renal) Failure
Prolonged Blockage
Prolonged infection- Untreated
Polycystic Kidney Disease
Diabetes
High Blood Pressure
Illegal Drug Use
Prescription Drugs
Treatment:
Dialysis
Kidney Transplant

38. Review Questions…
1. Which is the correct pathway for the elimination of urine? a) urethra, ureter, bladder, kidney b) kidneys, urethra, bladder, ureter c) bladder, ureters, kidney, urethra d) kidneys, ureters, bladder, urethra

39. Review Questions…
2. In humans, for carbon dioxide to be excreted, it must pass from the blood into: a) nephrons b) alveoli c) sweat glands d) the liver

40. Review Questions…
3. A blockage in a ureter would interfere with: a) urine entering the kidney b) urine entering the bladder c) urine leaving the body d) urea entering the kidney

41. Review Questions…
4. Which is NOT a metabolic waste in humans? a) carbon dioxide b) oxygen c) salt d) urea e) water

42. Review Questions…
5. In which form are nitrogenous wastes excreted in humans? a) ammonia b) uric acid c) urea d) amino acids

43. Review Questions…
6. Nitrogenous wastes are the result of metabolism involving: a) lipids b) carboohydrates c) inorganic compounds d) proteins

44. Review Questions…
7. In addition to water, the principal components of urine are: a) amino acids & fatty acids b) urea & salts c) ammonia & bile d) hydrochloric acid & urea

45. Review Questions…
8. Name a malfunction of the excretory system and explain how it can upset the homeostasis of an organism.