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The Excretory System.

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Presentation on theme: "The Excretory System."— Presentation transcript:

1 The Excretory System

2 Purpose Contributes to homeostasis
Regulates internal environment by eliminating metabolic waste products: Volume Electrolyte composition pH

3 Waste Products Some are metabolic E.g. Water, salts, CO2, and urea
Urea is a toxic compound that is produced when amino acids are used for energy (contain nitrogen).

4 Three Organs Kidneys Lungs Skin

5 1. Kidneys Main organs of excretion.
Remove excess water, urea & other excess mineral wastes from the body. Act as filters to remove wastes that are collected and transported by the blood. E.g. Surplus in water or electrolyte (salt) in blood = kidneys excrete in the urine.

6 2. Lungs Every time we exhale, we get rid of small amounts of water vapor and CO2. CO2 is the waste product of cells that must be removed from the body so you can take in oxygen.

7 3. Skin Excretes excess water, salts, and small amounts of urea through sweating.


9 The Urinary System Made up of:
Left and right kidneys Ureters Bladder Urethra Removes wastes and toxins from the blood and produces urine. Urine: made of water, excess salts, & urea

10 Kidney Structure Bean shaped
Either side of the spinal column, near lower back Size of your fist Each are attached to a renal artery & a renal vein

11 Renal Vessels Renal artery – blood from aorta
unfiltered and full of bodily wastes Renal vein – filtered blood

12 Ureters and Bladder Ureter leaves each kidney with fluid containing excess water, salts, urea & other waste products Ureters lead to the bladder; liquid wastes are deposited/stored here Expulsion of wastes controlled by specific sphincter muscles – voluntary control.

13 Kidney Regions 2 distinct regions: Inner Part: Renal Medulla
Outer Part: Renal Cortex

14 Nephrons In the renal cortex Working parts of the kidney
Each acts as an individual unit of filtration About 1 million nephrons per kidney

15 http://www. agefotostock. com/age/ingles/enam01b. asp

16 FYI The kidneys receive approximately 10% of the blood that is pumped out of our heart every minute. Adult kidneys filter approx. 180L of blood daily.

17 Filtration-Reabsorption-Secretion-Excretion

18 1. Filtration - Bowman’s Capsule (BC)
-Hollow bulb surrounding ball of capillaries (Glomerulus)


20 Filtration (cont’d) Blood enters via renal artery
Blood filters through permeable walls under pressure Filtered materials (urea, glucose, salts, & some vitamins) are called filtrates.

21 Filtration (cont’d) Platelets, red and white blood cells remain in the blood (too large to pass) Adult kidneys filter approx. 180L of blood daily.

22 Filtration-Reabsorption-Secretion-Excretion

23 2. Re-Absorption - Tubules
Some filtrates reabsorbed by active transport valuable & can’t be lost Water returns to blood through osmosis 99% of the water that is filtered out of BC is reabsorbed into your blood

24 Filtration-Reabsorption-Secretion-Excretion

25 3. Secretion - Tubules Excess fluid leaves BC & enters tubules
URINE. First part – Proximal Convoluted Tubule (PCT). carries fluid down into the Loop of Henle (LH).

26 3. Secretion - Tubules Urine concentrated in the tubule at the LH.
i.e.water reabsorbed Urine moves up Distal Convoluted Tubule (DCT) & meets ureter

27 Filtration-Reabsorption-Secretion-Excretion

28 4. Excretion Purified blood returns to the body through the renal vein, which runs to the Inferior Vena Cava Urine moves from the nephrons to ureters and goes to the bladder for storage Once urine is ready to leave the body, the urine will be expelled through the urethra. Stretch receptors in bladder

29 Recap:


31 http://www. colorado. edu/intphys/iphy3410saul/outlines08fall/nephron


33 Kidney Failure You have two kidneys in the body located on either side of the spine and extend a little below the ribs. Your kidneys are bean-shaped organs and is about the size of a fist. The kidneys receive approximately 10% of the blood that is pumped out of our heart every minute.

34 Your kidneys are responsible for the following:
Regulate fluids Balance chemicals Remove wastes Secrete hormones

35 Condition Explanation:
Progressive in nature Anemia possible – lack of iron Malnutrition (lack of appetite) Decrease well-being Increased risk for heart disease

36 Toxins build up in blood
Weight gain (excess fluids, swollen ankles, puffiness) Fluid imbalances – dizziness – nausea

37 Treatment Options: General
Limit fluid intake, high carb, low protein, low potassium diet Too much potassium can cause irregular heartbeat

38 Haemodialysis Most common method
Use of a machine (size of dishwasher) – blood flow through special filter to remove and filter wastes Clean blood returned to body Strict schedule – 3 times a week for 3 to 5 hours each time


40 Side effects Less energy Loss of time Once a month blood is tested to see how effective dialysis is – may not work forever!

41 Peritoneal Dialysis Removes extra water, wastes, and chemicals
Cleansing solution passed through catheter into abdomen After a couple of hours the solution is drained Does not require a machine Strict diet More recent advances, more flexibility (done at home)

42 Kidney Transplantation
Receive a healthy kidney from a living donor or a recently deceased donor When effective recovers quality of health AND life Yields longer life expectancy Could be long waiting lists (shortage of donors) Typical Surgery Risks (bleeding, infection, etc.) Anti-rejection medications after surgery – may weaken immune system Risk of rejection (body doesn’t accept kidney)

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