Excretion Flashcards
(23 cards)
What is excretion?
Removal of toxic materials and waste products of metabolism from organisms
Which organs are specialized for excretion in humans?
- Lungs
- Kidneys
- Liver
How is carbon dioxide excreted from the body?
Through the lungs during exhalation
What do the kidneys excrete?
- Excess water
- Excess salts
- Urea
What is urea?
A toxic waste product produced in the liver from the breakdown of excess amino acids
Why must carbon dioxide be excreted?
It can lower the pH of cells, reducing enzyme activity essential for metabolic reactions
What happens to excess amino acids in the body?
They are broken down in a process called deamination
What is the role of the liver in excretion?
Converts ammonia, a toxic byproduct of amino acid breakdown, into urea
What is the function of the kidneys?
Filter blood to remove urea and excess salts and water as urine
What connects the kidneys to the bladder?
Ureters
What is the urinary bladder?
An elastic muscular organ that stores urine
What is the function of the urethra?
Tube through which urine passes from the bladder to the outside of the body
What are the two main regions of the kidney?
- Cortex
- Medulla
What are nephrons?
Tiny structures in the kidneys that filter blood and form urine
What is the Bowman’s capsule?
A cup-like structure where each nephron begins
What is ultrafiltration?
The process where smaller molecules are forced out of capillaries into the Bowman’s capsule
What substances are forced out of the capillaries during ultrafiltration?
- Glucose
- Water
- Urea
- Salts
Where does reabsorption of glucose take place in the nephron?
Proximal convoluted tubule
How is glucose reabsorbed in the proximal convoluted tubule?
By active transport
What is a consequence of high blood glucose levels in diabetes?
Not all glucose can be reabsorbed, leading to glucose in urine
Where are necessary salts reabsorbed in the nephron?
Loop of Henle
What follows the reabsorption of salts in the nephron?
Water follows by osmosis
What determines the amount of water reabsorbed from the collecting duct?
How much water the body needs at that time
