Scheme of work
Unit: B3 Keeping internal conditions constant
Overview
From the specification;
B3.3 Homeostasis
- B3.3.1 Removal of waste and water control
- B3.3.2 Temperature control
- B3.3.3 Sugar control
The Big Picture for this unit
Students are taught about homeostasis relating to the removal of waste products and the regulation of temperature, water and glucose levels.
Carbon dioxide and urea are the two main waste products considered. Students need to be taught the origin of each and the importance of their removal. The role of the kidney in homeostasis and the removal of waste products are covered in more detail. Its role in reabsorption of useful substances such as water, glucose and other ions needs to be covered. Discussing the consequences of the kidney not functioning properly can be useful in helping to explain the role of the kidney. Once knowledge of the function of the kidney is secure, potential treatments for patients with kidney failure are introduced. Dialysis and kidney transplants are covered in terms of treatments.
Regulation of body temperature is introduced next. Experiments involving exercise or being outside in the cold can establish the fact that body temperature remains fairly constant despite a person perhaps feeling very hot or very cold. Once students have been taught how the body monitors its temperature, the methods for raising or lowering the core temperature can be introduced.
The regulation of blood glucose is covered and students could be told or shown on video the effects of very high and very low blood glucose to the importance of this process, possible diabetics could help lead this session. The role of the pancreas, insulin and glucagon are covered. With the basics in place, diabetes can be considered and the ways in which the condition can be managed are covered.
Common misconceptions
Sweating and the way in which the process cools the body are often poorly understood. Students need to be clear that it is the process of evaporation of the sweat from the skin that cools the body down. Vasodilatation and vasoconstriction are also possible areas in which students may have misconceptions. Some students might explain these processes in terms of blood moving closer to or further away from the surface. It is important that they understand that the blood vessels that supply the capillaries are not moving, they are just dilating or constricting. A common misconception is that capillaries constrict or dilate.
The misuse of the terms urea and urine, reinforce the facts, urea is made in the liver, and urine is produced in the kidneys and contains urea.
Opportunities for differentiation
The levels of support and guidance offered to students in completing the tasks within it. The kidney, for example, can be simplified in terms of the roles it performs to support students. To extend students, they could be given more detail and asked to interpret how the kidney carries out some of these roles.
Connections between topics
- B3, Chapter 1: Exchange of materials
- B3, Chapter 2: Transporting materials
AQA B3.3 Controlling internal conditions – Joe Ewen, Rebecca Timms and Rebecca Bartlett (Cheney School)