Coordination centre
| definition
Coordination centres in the brain, spinal cord and pancreas. They receive information from the receptors, process the information and instigate a response.
Key Terms
Coordination centre
| definition
Coordination centres in the brain, spinal cord and pancreas. They receive information from the receptors, process the information and instigate a r...
Effector
| definition
Effectors, such as muscles or glands create the response. Glands often release a hormone, which would restore the optimum condition again.
Body temperature
| homeostasis
Body temperature is one of the factors that is controlled during homeostasis. The human body maintains the temperature that enzymes work best, whic...
Body temperature
| enzymes
If body temperature increases over this temperature, enzymes will denature and become less effective at catalysing important reactions, such as res...
Body temperature
Body temperature is one of the factors that is controlled during homeostasis. The human body maintains the temperature that enzymes work best, whic...
The skin contains three layers:
The epidermis, dermis and a layer of fatty tissue.
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| Term | Definition |
|---|---|
Coordination centre | definition | Coordination centres in the brain, spinal cord and pancreas. They receive information from the receptors, process the information and instigate a response. |
Effector | definition | Effectors, such as muscles or glands create the response. Glands often release a hormone, which would restore the optimum condition again. |
Body temperature | homeostasis | Body temperature is one of the factors that is controlled during homeostasis. The human body maintains the temperature that enzymes work best, which is around 37°C. |
Body temperature | enzymes | If body temperature increases over this temperature, enzymes will denature and become less effective at catalysing important reactions, such as respiration. |
Body temperature | Body temperature is one of the factors that is controlled during homeostasis. The human body maintains the temperature that enzymes work best, which is around 37°C. If body temperature increases over this temperature, enzymes will denature and become less effective at catalysing important reactions, such as respiration. This process is controlled by the thermoregulatory centre, which is contained in the hypothalamus in the brain, and it contains receptors sensitive to the temperature of the blood. The skin also has temperature receptors and sends nervous impulses back to the hypothalamus. The hypothalamus responds to this information by sending nerve impulses to effectors in the skin to maintain body temperature |
The skin contains three layers: | The epidermis, dermis and a layer of fatty tissue. |
The skin | When we get too hot: | Sweat glands in the dermis release more sweat onto the surface of the epidermis. The sweat evaporates, transferring heat energy from the skin to the environment. |
The skin | When we get too cold: | Skeletal muscles contract rapidly and we shiver. These contractions need energy from respiration, and some of this is released as heat. Nerve impulses are sent to the hair erector muscles in the dermis, which contract. This raises the skin hairs and traps a layer of insulating air next to the skin. |
The control of body temperature is an example of a negative feedback mechanism. It regulates the amount of: | shivering (rapid muscle contractions release heat) | - sweating (evaporation of water in sweat causes cooling) |
The amount of blood flowing through the skin capillaries is altered by what? | vasoconstriction and vasodilation. |
vasodilation | definition | The increase in diameter of the skin arterioles to increase blood flow and increase heat loss by radiation. A response to being too cold. Heat lost by radiation |
vasoconstriction | definition | Narrowing of aterioles supplying the skin's blood capillaries, causing less blood to flow A response to being too cold. Little heat lost. |
Osmoregulation | definition | Osmoregulation is the control of water levels and mineral ions (salt) in the blood. |
Water content | osmoregulation | Water levels and mineral ions in the blood are controlled to keep the concentrations the same inside the cells as around them. This protects cells by stopping too much water from entering or leaving them by osmosis. If body cells lose or gain too much water, they do not function efficiently. |
Water content osmoregulation concentration is too high outside the cell | If the concentration of water is the same inside and out the cells, they remain in their normal state. If the water concentration is too high outside, water enters the cell by osmosis and they may burst. |
Water content osmoregulation concentration is too low outside the cell | On the other hand, if the water concentration is too low outside compared to the inside of the cells, water will leave by osmosis and the cells may shrivel. If body cells lose or gain too much water by osmosis they do not function efficiently. |
Water content osmoregulation animal cell hypotonic | More dilute solution out side the cell (hypotonic) Cell swell, burst |
Water content osmoregulation animal cell hypertonic | More concentrated solution outside the cell (hypertonic) Shrivelled cells |
Water content osmoregulation Plant cell hypotonic | More dilute solution outside the cell (hypotonic) normal turgid cell |
Water content osmoregulation Plant cell hypertonic | More concentrated solution outside the cell (hypertonic) Cytoplasm shrinks from the cell wall |
Human excretory organs are: | The organs of excretion in humans include the skin, lungs and kidneys. |
Human excretory organs | Water is lost from the body as: | sweat from the skin water vapour, from the lungs when we exhale urine from the kidneys |
What do sweat glands produce? | Sweat glands in the skin produce sweat. Water, ions and urea are lost from the skin as they are contained in sweat. |
Lungs | Water leaves the body via the lungs when we exhale as well as excess carbon dioxide. We cannot control the level of water, ion or urea loss by the lungs or skin. For example, in a hot climate, your body sweats to help keep you cool. In the same way, when we breathe out we lose water vapour, and we cannot alter the amount we lose. |
Kidneys | The kidneys are organs of the urinary system - which removes excess water, mineral ions and urea. Our bodies can control the amount of water and ions removed by the kidneys. This is called osmoregulation. |