(Paper 2) 5.4 Homeostasis: The Urinary System Flashcards
(49 cards)
Where is the thermoregulatory centre located?
In the hypothalamus of the brain.
What do receptors in the skin and brain detect?
Changes in body temperature.
What is the normal body temperature for enzymes to work effectively?
Approximately 37°C.
What happens when the body gets too hot?
Sweat is produced and evaporates, cooling the body.
Vasodilation increases blood flow to the skin, releasing heat.
Hairs lie flat.
What is vasodilation?
Widening of blood vessels to increase blood flow near the skin, allowing more heat loss.
What happens when the body gets too cold?
Shivering generates heat from respiration.
Vasoconstriction reduces blood flow near the skin to conserve heat.
Hairs stand up to trap a layer of air.
What is vasoconstriction?
Narrowing of blood vessels to reduce blood flow near the skin, preventing heat loss.
Why do we shiver when cold?
Rapid muscle contractions generate heat through respiration.
What role does the hair erector muscle play in thermoregulation?
Contracts to raise hairs and trap insulating air when cold; relaxes to flatten hairs when hot.
How is body temperature control an example of negative feedback?
It automatically reverses changes in temperature to maintain a stable internal condition.
What is osmoregulation?
The control of water and mineral salt levels in the blood to maintain a stable internal environment.
Why is water balance important for cells?
To prevent cells from gaining or losing too much water by osmosis, which can make them burst or shrivel and stop functioning properly.
What happens if the water concentration outside a cell is too high?
Water enters the cell by osmosis, and the cell may burst.
What happens if the water concentration outside a cell is too low?
Water leaves the cell by osmosis, and the cell may shrivel.
How do plant cells respond to water gain or loss?
Full of water: Turgid
Loses water: Flaccid, and the cytoplasm shrinks away from the cell wall.
What are the three excretory organs in humans?
Skin, lungs, and kidneys.
How does the skin contribute to water loss?
Through sweat, which contains water, ions, and urea.
How do the lungs contribute to water loss?
Water vapour is lost when we exhale, along with carbon dioxide.
Can we control water loss through the lungs or skin?
No, water loss through breathing and sweating cannot be controlled.
What is the main role of the kidneys in water balance?
To remove excess water, salts, and urea from the body in the form of urine.
What are ureters and how do they differ from the urethra?
Ureters carry urine from the kidneys to the bladder.
The urethra carries urine out of the body from the bladder.
What does urine contain?
Water, urea, and salts.
How is urea produced?
In the liver when excess amino acids are broken down.
What are nephrons?
Microscopic filtering units in the kidneys (over one million per kidney) that remove urea, excess water, and salts from the blood.
