Lesson Plan: B2.1.06

Hamble Lesson Observation Plan
Learning About
How is the water balance maintained in the body?
Keywords:
  • Dialysis: A procedure to remove waste products and excess fluid from the blood when the kidneys stop working properly. (1)
  • Diuretic: Any substance that promotes dieresis, the increased production of urine. (1)
  • Negative Feedback Cycle: A reaction that causes a decrease in function (1)
  • Risk Factor: Any attribute, characteristic or exposure of an individual that increases the likelihood of developing a disease or injury. (1)
Memory Anchor:
Method Precise Learning Objective Linked Question / Activity
(Designed for maximum working out)		 Stepping Stones Pitstop Check
(Thinking Map)
Students should be able to explain the effect on cells of osmotic changes in body fluids How do osmotic changes in fluids affect red blood cells?
(HT only) Students should be able to describe the effect of ADH on the permeability of the kidney tubules. (HT) How does ADH affect the permeability of the kidney tubules?
Water leaves the body via the lungs during exhalation. How does water from the lungs leave the body?
(HT only) The water level in the body is controlled by the hormone ADH which acts on the kidney tubules. (HT) What is the role of the hormone ADH?
Water, ions and urea are lost from the skin in sweat. What is lost from the skin through sweat?
(HT only) ADH is released by the pituitary gland when the blood is too concentrated and it causes more water to be reabsorbed back into the blood from the kidney tubules. This is controlled by negative feedback. (HT) How is water concentration controlled by ADH and what is this process controlled by?

Use the ABPI activities (see resources) to explain the negative feedback mechanism involved in control of water concentration in the blood. https://www.abpischools.org.uk/topic/homeostasis-kidneys/
There is no control over water, ion or urea loss by the lungs or skin. Can we control loss through the lungs and skin?
People who suffer from kidney failure may be treated by organ transplant or by using kidney dialysis. Students should know the basic principles of dialysis. How are people with kidney failure treated?

GF/EW: Discuss a moral dilemma – research cost of dialysis and transplants. Discuss considerations in terms of cost as to how kidney patients should be treated – lifetime dialysis, transplant, shortage of kidneys, buying kidneys from healthy people and prioritising lists for surgery. Produce arguments for and against the options.
Excess water, ions and urea are removed via the kidneys in the urine. What is lost in urine?
If body cells lose or gain too much water by osmosis they do not function efficiently What happens to body cells if they lose of gain too much water?
(HT only) The digestion of proteins from the diet results in excess amino acids which need to be excreted safely. In the liver these amino acids are deaminated to form ammonia. Ammonia is toxic and so it is immediately converted to urea for safe excretion. (HT) Where do excess amino acids come from and how do we safely get rid of them?
Students should be able to describe the function of kidneys in maintaining the water balance of the body. What is the function of the kidneys?
The kidneys produce urine by filtration of the blood and selective reabsorption of useful substances such as glucose, some ions and water. How do the kidneys produce urine?
Knowledge of other parts of the urinary system, the structure of the kidney and the structure of a nephron is not required.

Students should be able to translate tables and bar charts of glucose, ions and urea before and after filtration.

Links To the Big Ideas
ForcesParticlesEnergyCells