Excretion Flashcards
What is excretion?
|s the elimination of metabolic waste from the body
What are ectotherms?
They gain or lose heat from or to their external environment
What are endotherms?
They generate their own heat from metabolic reactions
What does filtration mean?
That water and small molecules pass under high pressure from the blood into the nephron
What does reabsorption mean?
That molecules pass from the nephron back into the blood
What does active transport mean?
That energy (in the form of ATP) is used to move molecules, often against a concentration gradient (from low concentrations to high concentrations)
What does secretion mean?
That some substances pass from the blood into the nephron.
What is homeostasis?
Is the maintenance of a constant internal environment in an ogranism.
What is skin composed of?
- The epidermis
- The dermis
Name the functions of the skin.
- Protection
- Vitamin Production
- Food Store
- Sense Organ
- Excretion
- Temperature Regulation
What does the skin do in cold conditions?
- Hairs stand up to keep skin warm
- Blood vessels become narrow to retain heat
- Shivering
What does the skin do in warm conditions?
- Sweating, which cools the body due to evaporation
- Blood vessels widen to lose heat
What are the main excretory organs?
- Lungs
- Skin
- Kidneys
What does the lungs excrete?
Water and carbon dioxide
What does the skin excrete?
Water and salts
What do the kidneys excrete?
Water, salts and urea
What does the urinary system consist of?
Two kidneys, two ureters, the bladder and urethra
What does the bladder do?
Stores urine
Where is the urine excreted?
Through the urethra
What are the functions of the kidneys?
- Excretion of water, salts and urea
- Osmoregulation
- Control of the pH of the blood and body fluids
What hormone is involved in controlling the volume of urine?
ADH
Where is ADH released from?
The pituitary gland
What does ADH cause?
- Increased reabsorption of water in the distal tubule and collecting ducts
- A low volume of urine
When is ADH not released?
When we drink sufficient water or consume a low-salt diet.
