Review the key concepts, formulae, and examples before starting your quiz.
🔑Concepts
A hormone is a chemical substance produced by an endocrine gland and carried by the blood, which alters the activity of one or more specific target organs.
Adrenaline is the 'fight or flight' hormone secreted by the adrenal glands. It increases heart rate and the concentration of blood glucose () to prepare the body for action.
The pancreas regulates blood glucose levels by secreting two hormones: Insulin (to lower blood glucose) and Glucagon (to raise blood glucose).
Insulin stimulates the liver to convert excess glucose () into stored glycogen.
Glucagon stimulates the liver to break down stored glycogen back into glucose () when blood levels are low.
The endocrine system transmits information via chemicals in the blood, which is generally slower than the nervous system's electrical impulses but produces longer-lasting effects.
Negative feedback mechanisms ensure that if a level (such as blood glucose) deviates from the norm, the body acts to return it to the .
📐Formulae
💡Examples
Problem 1:
Explain the role of adrenaline in preparing the body for vigorous exercise.
Solution:
Adrenaline is released from the adrenal glands. It causes an increase in heart rate and breathing rate. It also stimulates the liver to convert glycogen into .
Explanation:
Increased heart and breathing rates deliver more and to the muscles, increasing the rate of aerobic respiration to provide energy for muscle contraction.
Problem 2:
Contrast the speed and duration of the nervous system and the endocrine system.
Solution:
Nervous system: Speed is very fast (electrical impulses); Duration is short-lived. Endocrine system: Speed is slower (blood transport); Duration is long-lasting.
Explanation:
Nervous signals travel via neurones at up to , while hormones must travel through the circulatory system and take time to be broken down by the liver.