1. The Human Excretory System Chapter 11 Pages 374-381

2. Excretory System  The system that helps the body remove metabolic wastes  Examples: water, salt, wastes in blood

3. Parts of the Excretory System 1. Kidneys  regulate the amount of water, salts and other substances in the blood.  They are bean shaped structures that remove nitrogenous wastes (urine) and excess salts from the blood.

5. 2. Ureters  Tubes that carry urine from the pelvis of the kidneys to the urinary bladder 3. Urinary bladder  Temporarily stores urine until it is released from the body. 4. Urethra  The tube that carries urine from the urinary bladder to the outside of the body.  The outer end of the urethra is controlled by a circular muscle called a sphincter.

6. Excretory System

7. The Kidney has 3 sections: 1. The outer layer called the cortex is where the blood is filtered. 2. The inner layer is called the medulla, which contains the collecting ducts which carry filtrate (filtered substances) to the pelvis. 3. The inner collecting area is called the pelvis, it is a hollow cavity where urine accumulates and drains into the ureter.

9. How is blood is filtered?  The filtering units of the kidneys are called nephrons, which are located within the cortex and medulla  The tubes of the nephron are surrounded by cells and a network of blood vessels.  As a result, material that leaves the nephron enters the surrounding cells and returns to the bloodstream.

11. Parts of the Nephron 1. Glomerulus 2. Bowman’s capsule 3. Proximal Tubule 4. Loop of Henle 5. Distal Tubule 6. Collecting Duct

12. The Nephron 1. Glomerulus - a mass of thin-walled capillaries 2. Bowman’s capsule - a double-walled, cup-shaped structure. 3. Proximal Tubule - leads from the Bowman’s capsule to the Loop of Henle 4. Loop of Henle - a long loop which extends into the medulla 5. Distal Tubule - connects the loop of Henle to the collecting duct.

14. How does the kidney function? Stage 1: Filtration  Blood enters Bowman’s capsule through the renal artery and is branched into the glomerulus.  Blood pressure forces the blood plasma and small particles into the surrounding capsule called the nephric filtrate

15.  Larger particles, like blood cells and proteins stay in capillaries.  The nephric filtrate is pushed out of the capsule and into the proximal tubule.  This is where reabsorption begins.

16. Stage 2: Reabsorption  This begins when the nephric filtrate enters the proximal tubule.  Materials (like water, glucose, amino acids and ions) that are needed by the body are taken up by the bloodstream, by the processes of osmosis, diffusion and active transport.

17.  When the filtrate reaches the end of the proximal tubule, the fluid inside is isotonic with the surrounding cells.  Once the filtrate enters the loop of Henle, water is removed from the filtrate by osmosis. This happens because there is a higher concentration of sodium (salt) in the cells of the loop of Henle.

18. Nephron Function: SECRETION  Occurs in the distal tubule  Involves active transport (pumping) of substances from the capillaries into the tubule  Substances need to be forcibly removed from blood include hydrogen ions, creatinine and drugs

19. Nephron Function: ELIMINATION  The fluid than enters the collecting duct as urine.  Urine passes through the pelvis into the ureter.  Most of the water, ions and useful nutrients (glucose, amino acids) have been reabsorbed.  Reabsorption and urine production is regulated by the productions of anti-diuretic hormone (ADH)

22. Function of the Kidney 1. To filter blood (at any given time 20% of the body’s blood is in the kidneys) 2. To maintain homeostasis in the body Such as water pH, secrete hormones to control RBC production and activate vitamin D production in the skin.Such as water pH, secrete hormones to control RBC production and activate vitamin D production in the skin.

23. 3. To excrete cellular waste such as: a) urea (produced in the liver from the breakdown of protein) b) uric acid (waste from breakdown of DNA or RNA) c) creatinine (waste product of muscle action).

25. What can you tell from urine? PregnancyPregnancy DiabetesDiabetes DrugsDrugs

26. When Blood-water levels are too low  Osmoreceptors and baroreceptors to detect low water/salt balance or low blood pressure  The hypothalamus of the brain stimulates the pituitary gland to secrete anti-diuretic hormone.

27.  ADH travels to the kidneys where it increases the permeability of the tubules and collecting ducts  Result More water is reabsorbed into the blood More water is reabsorbed into the blood Blood volume, and thus blood pressure increases Blood volume, and thus blood pressure increases More concentrated urine is produce More concentrated urine is produce

28. When Blood-water levels are too high  Osmoreceptors and baroreceptors to detect high water/salt balance or high blood pressure  The hypothalamus of the brain does not stimulate the pituitary gland to secrete anti- diuretic hormone.

29.  Permeability of collecting ducts and tubules is un-affected since no ADH was produced  Result Less water is reabsorbed into the blood, and more in urine is produced Less water is reabsorbed into the blood, and more in urine is produced Blood volume, and thus blood pressure decreases Blood volume, and thus blood pressure decreases More dilute urine is produce More dilute urine is produce

30. Disorders of the Excretory System  Our excretory system is very important in maintaining homeostasis. There are certain conditions which can affect the excretory system. We will discuss some of these common disorders.

31. UTI (Urinary Tract Infection)  Is a very common disorder. If the bladder has become infected, it is known as cystitis. If the urethra is infected., it is called urethritis.  UTI is more common in women than men because of differences in anatomy.  Symptoms include painful urination burning sensation), frequent urination (even if no urine present) and bloody or brown urine.  This can lead to chills, fever, nausea, vomiting and upper abdomen tenderness.

32. Kidney Infections  Result when an infection reaches the kidneys and becomes known as pyelonephritis.  Common causes can be infection from elsewhere in the body or obstruction of the prostate gland (usually in older men).  For children, infection can be caused by the tube that drains urine from the kidneys and the bladder.

33. NOTE :  If left untreated, all UTI’s can lead to permanent kidney damage and possible kidney failure.  The general treatment is by antibiotics. A person needs to maintain good personal hygiene when eliminating wastes (liquid and solid forms) from the body.  Also, a person should drink lots of water.

34. Kidney Stones  Are also a common kidney disorder. They form when chemicals in the urine precipitate out and form crystals.  The most common crystals are from calcium oxalate, while others could be from uric acid and cystine.  Kidney stones are more common in men than women and can reoccur at any time.  Factors such as recurrent urinary bladder infections, insufficient water intake and consumption, low levels of physical activity, and too much Vitamin C and D intake can lead to kidney stones.  One of the best ways to decrease the occurrence of stones is to drink lots of water and to change your dietary habits.

35. Kidney Stones (cont)  Symptoms include severe back or abdomen pain, blood in the urine, nausea and vomiting.  Diagnosis involves a complete medical examination, including X-rays.  Treatment may vary from letting the stones pass through the urinary tract to ultrasound shock (or lithotripsy) to disintegrate the stones to a small size that can be passed through the urinary tract.  Real large stones require surgery for removal.

36. Disorders of the Excretory System Urinary Tract infection (UTI) – –Typically caused by bacterial infections from other sources – –Cystitis – if on the bladder is infected – –Urethritis – if only the urethra is infected – – More common in females than males because of anatomical differences Symptoms – –Painful urination (burning sensation), urge to urinate when there is no urine present, discolored urine – –Typical infection symptoms: fever, nausea, vomiting, chills – –May result in pyelonephritis if infections reaches kidneys. Treatments: – –Antibiotics or surgery Prevention: – –Personal hygiene (wiping front to back) – –Drinking lots of water

37. More on Disorders Kidney Stones – –Chemicals in the urine precipitate out and form stones Typically: Calcium oxalate, uric acid or cystine crystals – –More common in men than women – –Often are recurring in people Causes: – –Recurring UTI’s, insufficient water consumption, low activity levels, too much vitamin C and D Symptoms: – –Severe pain in lower back/ abdomen, blood in urine, vomiting and nausea Treatment and Diagnosis: – –X-rays & urine testing – –Medications to break down stones and drinking plenty of water to pass stones – –Small stones may be treated by ultrasound (Lithotripsy) to disintegrate the stones. – –Surgery may be needed in small stones