Post on 18-Jan-2016
+
Excretory System38-3
+By the end of this lesson on excretion you should be able to:
1) Describe the organs that make up the excretory system
2) Explain how the kidneys work to maintain homeostasis in your body
3) Explain how the lungs and the skin participate in excretion
+Excretion:
Removes the wastes produced by our cells like excess nitrogenous wastes (urea), salts, and carbon dioxide
Urea – a toxic compound produced when amino acids are used for energy that is produced by the liver
Major excretion organs are the skin,liver, kidneys, and lungs
What waste does each organ release???
The Kidneys
The size of a clenched fist
Removes urea, excess water and other wastes from the blood in the renal artery
Transports wastes to the urinary bladder
+What does a kidney do?
•Kidneys filter the blood!!!
Parts of the Kidneys
Inner part – renal medulla
Outer part – renal cortex
Basic functional units – nephrons
1 million per kidneyFilters, reabsorbs and
secretesEmpties wastes into the
ureter, leading to the urinary bladder
Filtration
Occurs in the capillary network called the glomerulus that is surround by the Bowman’s capsule
Filters all the blood in the body every 45 minutes
Pressure pushes out the filtrate made of water, urea, glucose, salts and amino acids
+Reabsorption
Occurs in the renal tubules
Materials are actively transported from the filtrate back into the blood (to stay in the body) leaving the urine - the body’s waste product
What materials do you think should stay in the body and not leave in the filtrate as waste?
Where doe the blood go next?
+Secretion
Occurs in the renal tubules
Materials such as H+, K+, ammonia, and drugs are transferred from the blood to the filtrate
The filtrate travels into the collecting duct as urine. What does it contain?
The urine is stored in the bladder and then released through a tube called the urethra and removed from the body
+So how do the kidneys help to maintain homeostasis???
Regulate water content of the blood
Maintain blood pH
Removes wastes from the blood
Click here for a review video
+SELF QUIZ:
1) What other systems work with the excretory system?
2) How is the liver involved in excretion?
3) Complete the worksheets