MCAT BIO CH. 10 PART 1 Flashcards
What are the organs of the excretory system?
- Liver
- Colon
- Skin
- Kidneys
What is the liver responsible for?
Excreting many wastes by chemically modifying them and releasing them into bile
What type of products does the liver deal?
Hydrophobic or large waste products that cannot be filtered out by kidney
What can the kidney dissolve?
Eliminate small hydrophils dissolved in plasma
Which organ synthesizes urea?
The liver
Where does the liver excrete urea?
Into the bloodstream
What is urea?
A carrier of excess nitrogen resulting from protein breakdown
Why must free nitrogen be converted into urea?
Because free ammonia is toxic
What is the purpose of the large intestine?
Reabsorb water and ions from feces
What does the skin produce and how is it an excretory organ?
Produces sweat; excretory role is secondary as its used for temperature level
What is the purpose of kidneys?
Excretion of hydrophilic wastes
Which substances must be excreted in the urine?
Urea, sodium, bicarbonate and water
What is the role of the kidney based on its excretion?
Homeostasis
What are the excretory and homeostatic roles of the kidney?
- Excretion of hydrophilic wastes
- Maintenance of constant solute concentration and constant pH
- Maintenance of constant fluid volume
What is the first process of the kidney in keeping homeostasis?
Filtration
What is the filtration of the kidney?
Passage of pressurized mood over a filter
What does the kidney filter?
Cells and proteins remain in the blood; water and small molecules are squeezed out into the renal tubule
What is the fluid in the renal tubule of the filtration kidney called?
Filtrate
What is the second process of the kidney in keeping homeostasis?
Selective reabsorption
What happens during selective reabsorption of kidney homeostasis?
Take back useful items and leave wastes and some water in the tubule
What is the third process of the kidney in keeping homeostasis?
Secretion
What is secretion based on kidney homeostasis?
Involves addition of substances to the filtrate
What is the last step to urine formation?
Concentration and dilution
What is concentration and dilution based on urine formation?
Selective reabsorption of water