9.4 - Homeostasis Flashcards
What is homeostasis?
Homeostasis is the maintenance of a constant internal environment. The nervous system and hormones are responsible for this.
Why is body temperature controlled?
To maintain the temperature at 37 degrees Celsius, at which the body’s enzymes work best.
Why is blood sugar controlled?
It’s controlled to provide cells with a constant supply of glucose for respiration, and is controlled by insulin. (It controls the release and storage of glucose)
How and why is water content controlled?
It is controlled to protect cells by stopping too much water from entering/leaving them. Controlled by water loss from lungs (exhale), skin (sweat), and the body (urine produced by kidneys).
What does endothermic mean?
Animals that can keep their temperature almost constant, even if the environment’s temperature changes. They get their hear energy from within themselves.
What does ectothermic mean?
The animal’s body temperature matches it’s environment’s temperature. It does not get it’s heat energy from within itself.
Why do endothermic animals have to eat more food than ectothermic ones?
Endothermic animals get their heat energy from food, by respiration. In order for their metabolism to keep going regardless of the environment’s temperature, they need to eat a lot more food.
What are the two layers the skin is made up of?
Epidermis (top) and dermis (bottom).
What do the sweat glands in the dermis do?
They secrete a liquid called sweat (mostly water, urea and salts), which travel up the sweat ducts and out onto the surface of the skin through the sweat pores (helps in temperature regulation)
What is the adipose tissue?
A layer of fat underneath the dermis, made up of cells that contain large drops of oil. It helps insulate the body against heat loss and act as an energy reserve.
What is the hypothalamus?
A part of the brain at the centre of the control mechanism that keeps internal temperature constant. It coordinates the activities of the parts of the body that can cause temperature changes.
What happens to your body when the temperature falls? (detailed)
When body temperature drops below 37 degrees Celsius:
- Muscles contract and relax very quickly, producing heat (shivering)
- Metabolism will increase (releases more heat)
- Hair stands up - erector muscles in skin contract (cat - traps thick layer of warm air next to skin, human - goose pimples)
- Vasoconstriction - arterioles close to the skin’s surface become constricted/narrower, causing only little blood to flow through them (blood doesn’t lose much heat to air)
What happens to your body when the temperature rises? (detailed)
- Hair lies flat (erector muscles relax)
- Blood system loses heat - arterioles dilate - Vasodilation - heat is readily lost from the blood into the air
- Sweat glands secrete sweat - lies on the surface of the hot skin - water evaporates, cooling the body
What is negative feedback? (def.)
The way the hypothalamus, skin and muscles work together to keep internal body temperature within narrow set limits.
What is the process of negative feedback? (detailed)
The temperature rise is sensed by the hypothalamus. It sends nerve impulses to bring about actions to help cool the blood. When the cooler blood reaches the hypothalamus, this responds by sending nerve impulses to your skin that being about actions to help reduce the rate at which heat is lost from the blood, and rate of heat production in the muscles increases. As soon as the hypothalamus senses the lowered temperature, it stops these actions and starts of other actions that help raise the temperature.
