B1f Flashcards
What does the body work to maintain steady levels of?
Temperature, water and carbon dioxide and this is essential to life.
What does maintaining a constant internal environment involve?
Balancing bodily inputs and outputs and is called homeostasis.
Why is temperature kept at steady levels?
You need to get rid of excess body heat when you’re hot, but retain heat when the environment is cold.
Why is water kept at steady levels?
You need to keep a balance between the water you gain and water you pee, sweat and breathe out.
Why is levels of carbon dioxide kept at steady levels
Respiration constantly produces carbon dioxide which you need to get rid of.
How are negative feedback mechanisms used to maintain a constant internal environment?
Changes in the environment trigger a response that counteracts the changes - e.g. a rise in body temperature causes a response that lowers body temperature.
This means that the internal environment tends to stay around a normal, the level at which the cells work best.
This only works within certain limits - if the environment changes too much then it might not be possible to counteract it.
What is the core temperature of the human body?
37 degrees Celsius.
What are the appropriate procedures to measure body temperature?
In the ear, finger, mouth or anus using a clinical thermometer, sensitive strips, digital recording probes or thermal imaging.
How can heat be gained or retained?
By respiration, shivering which generates heat in the muscles by the movement, exercise, less sweating, less blood flow to the surface of the skin or clothing.
How can sweat increase heat transfer to the environment?
When you’re too hot lots of sweat is produced - when sweat evaporates it uses heat from the skin. This transfers heat from your skin to the environment, which cools you down.
What is the body temperature of 37 degrees Celsius the optimum temperature for?
The action of many enzymes.
What can high temperatures cause?
Dehydration which could lead to heat stroke which can kill you.
What can low temperatures cause?
Hypothermia and death.
What is vasodilation?
Blood vessels close to the surface of the skin widen. This allows more blood to flow near the surface, so it can radiate more heat into the surroundings.
What is vasoconstriction?
Blood vessels near the surface of the skin constrict so that less heat can be transferred from the blood to the surroundings.
How is blood temperature monitored by the brain?
There’s a thermoregulatory centre in the brain. It contains receptors that are sensitive to the blood temperature in the brain. It also receives impulses from the skin that provide information about skin temperature. The brain can respond to this information and bring about change’s in the bodies temperature using the nervous and hormonal systems to initiate temperature control mechanisms.
What does the pancreas produce?
The hormone insulin.
What is type 1 diabetes caused by?
The failure of the pancreas to produce insulin.
How does insulin travel around the body?
Around the blood.
What does insulin control?
Blood sugar levels.
How can type 2 diabetes be controlled?
By limiting the intake of foods rich in simple carbohydrates, i.e. sugar.
How can type 1 diabetes be controlled?
Partly by having a carefully controlled diet. By insulin therapy involving injecting insulin into the blood several times a day, often at mealtimes. This makes sure that glucose is removed from the blood quickly once food has been digested. This stops the levels of glucose in the blood from getting too high and is very effective as a treatment. The amount of insulin need depends on the persons diet and how active they are.
Why are responses controlled by hormones usually slower than responses controlled by the nervous system?
Insulin is a hormone. Hormones travel in the blood, so it can take quite a while for them to get to where they’re needed in the body. Electrical impulses sent along the nerves travel much faster. This means it takes the body longer to respond to a hormone than to a nervous impulse.
How does insulin help to regulate blood sugar levels?
Blood with too much glucose means insulin is released by the pancreas. Glucose is removed by the liver as insulin makes liver turn glucose into glycogen, reducing blood glucose.
Blood with too little glucose means insulin is not released. Glucose is added by the liver as the liver turns glycogen into glucose, so blood glucose is increased.
