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EXCRETORY SYSTEM

EXCRETORY SYSTEM. What is Excretion?. The process of ridding the body of waste in order to maintain homeostasis. Excretory System. How does the excretory system maintain homeostasis? It regulates heat, water, salt, acid-base concentrations and metabolite concentrations. ORGANS OF EXCRETION.

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EXCRETORY SYSTEM

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  1. EXCRETORY SYSTEM

  2. What is Excretion? • The process of ridding the body of waste in order to maintain homeostasis.

  3. Excretory System • How does the excretory system maintain homeostasis? • It regulates heat, water, salt, acid-base concentrations and metabolite concentrations

  4. ORGANS OF EXCRETION • Skin and associated glands: • sweat is removed by skin as a waste product trying to Remove heat and salts • Lungs:Removes carbon dioxide • Liver: • get rid of unneeded wastes in the body. It changes toxic ammonia, which is a poisonous gas , to urea, a harmless fluid. • Kidneys; removes nitrogenous waste (urea)

  5. What is the Function of the Human Excretory System? • Maintain proper water balance in the body and to also remove liquid waste (urine) • Kidneys filter approximately200L of blood or filtrate everyday • Remove approximately 1-2 L of fluid everyday

  6. Parts of the human excretory System • Kidneys • Ureters • Urinary bladder • urethra

  7. Urinary System

  8. Kidneys • Kidneys: • filter blood to produce urine.. Maintain water balance and rid body of nitrogenous waste (urine) created by the liver • The kidney is a lima bean shaped structure found on both sides of the spinal column in the lower back

  9. The Kidney

  10. KIDNEY PARTS • Kidney has three distinct regions • Cortex: • the outer part • Function: filter blood • Medulla: • the middle part made up of collecting ducts • Function: collect filtrate (filtered materials from the blood) and carries it to the renal pelvis • Pelvis: • the inner cavity where urine collects. It is connected to the ureters • Function: Filtrate (now called urine) drains from the pelvis into the ureters for removal

  11. MAJOR FUNCTIONSOF KIDNEYS • 1. Filters blood of: ØUrea – formed in the liver from the breakdown of ammonia ØCreatinine – formed in the muscles ØUric Acid – formed as a result of the breakdown of nucleic acids (DNA and RNA)

  12. 2. Controls the balance of water in our bodies • 3. Regulates pH of the blood • 4. Regulates the concentration of dissolved ions in the blood

  13. 5. Secretes a hormone that causes a production of red blood cells • 6. Activates Vitamin D production in the skin

  14. Parts of Excretory system cont’d • Urinary Bladder: • hollow muscular pouch located in the pelvis • Function: hold urine until it is released from the body. A typical bladder is able to hold up to about 500ml of urine. • Urethra: • hollow tube leading from the bladder to the outside of the human body • function: carries urine from the bladder to the outside of the body. • Ureters: • hollow tubes connecting the renal pelvis to the urinary bladder • Function: carry urine from the kidney to the urinary bladder

  15. IMPORTANT BLOOD VESSELS • Renal Artery: carries contaminated blood into the kidney. • Renal Vein: carries purified blood from the kidney and returns it back into circulation by way of the inferior vena cava.

  16. NEPHRONS • Tiny filtering units called nephrons fill the cortex and medulla of the kidney. • Basic functional unit of kidney responsible for filtering the blood and maintaining proper water balance • Extends from renal cortex (glomerulus/ Bowman's capsule) into the renal medulla (loop of Henle) • Each kidney contains 1 to 1.25 million nephrons.

  17. Parts of the Nephron • Renal artery: • this is the artery that carries blood TO the kidney to be filtered • Renal vein: • this is the vein that carries blood FROM the kidney AFTER it has been filtered • Glomerulus; • A tight ball of blood capillaries located in the Bowman's capsule of Nephron. • Blood pressure created here causes material to be filtered from the blood • Bowman's capsule: • A cup shaped structure that receives filtrate from the Glomerulus • Proximal tubule: • tube connected to the Bowman's capsule. • Filtrate enters the proximal tube from the Bowman's capsule. • Reabsorption of Amino Acids and Glucose occurs here

  18. Loop of henle: • long u shaped tube that extends into the renal medulla. Responsible for maintain salt balance by reabsorption or releasing salt in the filtrarte • Distal tubule; • tube extending from the loop of henle. • It also reabsorbs materials from the filtrarte . Tubular secretions occurs here. Materials such as creatinine and drugs are added to the filtrate • Collecting tubule: • tube that extends from the distal tubule to the renal pelvis. This portion of the nephron is mainly responsible for reabsorption of water

  19. Nephron Function (4 stages) • 1. Filtration: • Blood travels from the renal artery, to an arteriole and then into the glomerulus, a mass of capillaries surrounded by the Bowman’s capsule.

  20. Blood pressure forces some plasma of the blood, containing both waste and useful material, into the Bowman’s capsule. This material is called the nephricfiltrate.

  21. The filtrate contains such things as: water, urea, uric acid, salt, glucose, amino acids, ions and vitamins.

  22. 1. Filtration • Filtration – Hydrostatic pressure (blood pressure) forces • water and dissolved substances out of the glomerular blood into Bowman’s capsule. • H2O, glucose, amino acids, electrolytes, wastes • Averages 125 ml/min for both kidneys • Æ180 liters/day • The vast majority of the filtrate must be taken back

  23. 2. Re-absorption: • From the Bowman’s capsule the filtrate is pushed into the proximal tubule. The process of re-absorption, of useful materials within the filtrate, into the capillary network that surrounds the nephron than begins.

  24. Reabsorption occurs by osmosis, diffusion, and active transport • Reabsorbed materials include water, glucose, amino acids, ions and vitamins

  25. When the filtrate reaches the end of the distal tubule the solution is isotonic (the filtrate and the surrounding cells have the same concentration of water and solutes).

  26. The filtrate then moves down the descending loop of Henle; as the loop descends further into the inner medulla, sodium concentrations in the surrounding tissue increase which draws water out of the filtrate (by osmosis).

  27. At the bottom of the loop sodium ions in the filtrate are at high concentration and therefore diffuse out of the tubule.

  28. Positive sodium ions are followed by negative chloride ions • Water cannot reenter the ascending loop because this loop is impermeable to water

  29. H2O - osmosis • NaCl - active transport • Glucose, amino acids - active co-transport

  30. 3. Secretion • Occurs in the distal tubule • Involves active transport of substances from the capillaries into the tubule • Substances include hydrogen ions, creatinine and drugs

  31. 4. Elimination • The fluid than enters the collecting duct as urine. It passes through the pelvis into the ureter. • Most of the water, ions and useful nutrients (glucose, amino acids) have been reabsorbed.

  32. Path of filtrate through nephron: • Bowman’s capsule - proximal tubule - loop of Henle - distal tubule - collecting duct

  33. Control of Water Balance • When water levels are too low: • The hypothalamus stimulates the pituitary gland to secrete a hormone called anti-diuretic hormone (ADH) or Vasopressin. ADH travels through blood to kidneys.

  34. 2) ADH increases the permeability of the tubules and collecting ducts 3) More water is reabsorbed into the blood so the urine is more concentrated

  35. When water levels are too high: • Hypothalamus doesn’t stimulate ADH secretion • Little water is reabsorbed into the blood so the urine is more dilute.

  36. Other • Aldosterone: affects distal tubule and collecting tubule to reabsorb sodium ions • ANP( atrial natruuretic peptide: increase glomerulus filtration rate by dilating the arterioles and inhibits the collecting ducts from reabsorbing sodum.

  37. Excretory System Disoders • These are problems associated with the kidneys, bladder , or ureters • We will examine the following disorders: • 1. Urinary tract Infections • Cystitus • Ureyhritis • Pyelonephritis • 2. Kidney stones • 3. Kidney Failure

  38. Urinary Tract Infections UTI’s • These are Bacterial Infections of the kidneys, bladder or Urethra • There are 3 types of UTI’s • 1. Cystitis- infection of the bladder • 2. Urethritis- infection of the urethra (tube leading from the bladder to the outside of the body) • 3. Pyelonephritis- infection of the kidney

  39. Causes of UTI’s • Bacteria from the anus (females • Blocked prostate (men) • Bacterial infection from other areas of the body • Note: UTI’s are more common in females than males

  40. Symptoms of UTI’s • Painful urination • Burning sensation • Bloody or brown urine • Chills, fever, nausea

  41. Danger and Treatments • Danger of UTI’s • Permanent damage to the kidneys and possible kidney failure. • Treatments of UTI’s • antibiotics

  42. 2. Kidney Stones • What are Kidney Stones? • These are hard crystals of calcium oxalate or uric acid that foem in the kidney bladder or ureter/urethra • Kidney stones form when materials in the urine solidify • Kidney stones are more common in men than women

  43. Causes of Kidney Stones? • Urinary tract infections • Not drinking enough water • Too much vitamin C and D

  44. Symptoms of Kidney Stones • Severe pain in abdomen and back • Blood in urine • Nausea • vomiting

  45. Treatments of Kidney Stones • Change diet • Drink lots of water • Ultrasound( breaks them up so they can pass) called lithotripsy • Surgery (open) • Incision through the back (nephrolithotomy • Insertion of thin telescopic instrument into urinary tract( ureteroscopsy)

  46. Kidney Failure • When the kidneys are not working correctly, waste products and excess fluid can build up and the levels of sodium, potassium, phosphate and calcium are not regulated correctly. 

  47. symptoms of kidney disease, which can include • high blood pressure, • excessive tiredness, • fluid retention and • possibly lower back pain.

  48. Causes • Kidney damage can occur for a number of reasons • diabetes, • high blood pressure, • infections and a group of diseases that affect the glomerulus.  • The kidneys also need an adequate supply of blood, so if there is something wrong with the blood vessels to the kidney, such as a narrowing, this will prevent the kidneys from working efficiently.

  49. Treatments • dialysis • cleans and filters your blood using a machine to temporarily rid your body of harmful wastes, extra salt, and extra water. Hemodialysis helps control blood pressure and helps your body keep the proper balance of important chemicals such as potassium, sodium, calcium, and bicarbonate. • Dialysis can replace part of the function of your kidneys. Diet, medications, and fluid limits are often needed as well. Your diet, fluids, and the number of medications you need will depend on which treatment you choose.

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