Homeostasis Flashcards
All 16 cards in this deck
What is homeostasis?
The maintenance of a constant internal environment inside the body, in response to internal and external change.
Why must the body maintain a constant internal environment?
So that cells work properly and enzymes stay at their optimum conditions.
Give three conditions in the body that are kept constant by homeostasis.
Blood glucose concentration, body temperature and the water content of the body.
What is negative feedback?
When a change in a condition triggers a response that brings the level back towards normal.
Which organ detects changes in blood glucose concentration and releases insulin and glucagon?
The pancreas.
What are the steps by which insulin lowers blood glucose concentration?
e.g. blood glucose rises after a meal
The pancreas detects high blood glucose and releases insulin into the blood.
Insulin makes liver, muscle and other cells take up glucose from the blood.
The liver and muscles convert the glucose into glycogen to store it, so blood glucose falls back to normal.
What does the hormone glucagon do when blood glucose concentration is too low?
It makes the liver convert stored glycogen back into glucose, which is released into the blood, raising blood glucose concentration.
True or false? Glucagon and glycogen are two names for the same substance.
False. Glucagon is a hormone from the pancreas; glycogen is the storage carbohydrate held in the liver and muscles.
On a blood glucose graph, why does the concentration fall during a period of exercise?
The muscle cells use up glucose from the blood because of increased respiration.
What causes type 1 diabetes?
The pancreas does not produce enough insulin (or any), so blood glucose concentration stays too high.
How is type 1 diabetes controlled?
Insulin injections, together with a controlled diet and regular exercise.
How is type 2 diabetes controlled?
Exercise, a controlled diet and weight loss, and medication such as metformin, to reduce blood glucose.
What is the equation for body mass index (BMI)?
BMI = mass in kg ÷ (height in m)²
How is a person's waist : hip ratio calculated?
waist : hip ratio = waist circumference ÷ hip circumference (both measured in the same units, so the ratio has no unit)
True or false? Data showing that people with a high BMI are more likely to have type 2 diabetes proves that high BMI causes type 2 diabetes.
False. It shows a correlation only; correlation alone does not prove that one factor causes the other.
Why does blood glucose rise too high in a person with type 2 diabetes?
Their body cells no longer respond properly to insulin (insulin resistance), or their pancreas makes too little insulin.