The Excretory System

1. http://www.youtube.com/watch?v=qxb2_d9ilEw The Excretory System

2. REGULATIONExcretory & Nervous Systems • Regulation within animal systems requires maintaining homeostasis- the ability of the body or a cell to seek and maintain stability within its internal environment when dealing with external changes • There are several organ systems that work together to maintain an organism’s internal environment, despite changes that occur in its external environment. • The excretory system helps regulate the concentration of water and other components of body fluids.

3. Homeostatic Control Mechanisms • Communication within the body is essential for homeostasis. • Homeostasis is accomplished primarily by: • Endocrine system (blood borne hormones) • Nervous system (electrical signals)

5. Negative Feedback vs. Positive Feedback Mechanisms • Negative Feedback Mechanism – The net effect of the response to the stimulus is to shut off the original stimulus or to reduce its intensity. • Examples: Thermostat or body temperature, heart rate, blood pressure, breathing rate, blood levels • Positive Feedback Mechanism – Feedback that tends to cause a variable to change in the same direction as the initial change; enhances the stimulus • Examples: Blood clotting, birth of a baby • More rare in the body

6. Excretion • Excretion – the process by which metabolic wastes are eliminated from the blood • One part of the many processes that maintain homeostasis. • Every cell in the body produces metabolic wastes, such as excess salts, carbon dioxide, and urea

7. Excretory System Function • The Excretory System Maintains Homeostasis In 3 Steps: • Filtration- Filters substances from the blood • Reabsorption- Regulate the chemical composition of body fluids by retaining the proper amounts of water, salts, and nutrients • Secretion- Elimination of wastes in the form of urine

8. Excretory System Evolutionary Trends in Excretion Complex Simple

9. Main Organs of the Excretory System • Kidneys • Renal artery • Renal Vein • Ureters • Urinary Bladder • Urethra

10. Major Organs of the Excretory System • Kidneys (renal = kidney)- • Located on either side of the spinal column near the lower back. • Paired organs that receive blood via the renal artery • The main filtering units are tissues called nephrons that separate the components of the blood • Every 45 minutes kidneys filter all the blood in your body • Excess water and urea in the form of urine leave the kidney via the ureter where it leaves as urine out the urethra • Filtered blood leaves kidneys and returns to circulation carrying nutrients, salts, and water via the renal vein

11. Ureter • A tube, called the ureter, leaves each kidney carrying urine to the urinary bladder

12. Urinary Bladder • The urinary bladder is a saclike organ where urine (a mixture of urea, water, and salt) is stored before being excreted. Foley Catheter

13. Urethra • Tube that carries urine from bladder to the outside of the body

14. Excretory System Levels of Organization Renal cells, bladder cells, etc… Nephrons Kidneys, Bladder, Ureter, Urethra Excretory

15. Kidney Stones • Sometimes substances such as calcium, magnesium, or uric acid salts in the urine crystallize and form kidney stones. • When kidney stones block the ureter they cause great pain. • Often treated using ultrasound, in which the sound waves pulverize the stones into smaller fragments • Prevent by: drink lots of water, diet lower in protein (N), sodium

16. AntidiureticHormone ADH Process Hypothalamus | Tells pituitary that amount of waterin blood is low. Tells pituitary that amount of water in blood is high. High amounts of water in blood and low amount of urine produced. Low amounts of water in blood and high amounts of urine produced Pituitary | Stops releasing ADH intobloodstream Releases ADH into bloodstream Kidneys | Reabsorbs more water. Reabsorbs lesswater.

17. Other Organs: • Lungs of the respiratory system remove CO2 from blood. • Skin of the integumentary system excretes water, urea, salts, and other wastes through sweat. • The circulatory system brings wastes to the lungs, kidneys, and skin for excretion.

18. Kidney Damage • Humans have two kidneys and can survive with only one. • If both kidneys are damaged by disease or injury, there are two ways to keep an individual alive. • Kidney Transplant • Kidney Dialysis Machine • Expensive • Time consuming (3 X /week for few hours)