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Look Mama, It’s Alive!
Human Feedback Systems
TAKS Objective 2 – The student will demonstrate an understanding of living systems and the environment
Interdependence occurs among living systems
TEKS 8.6The student knows that interdependence occurs among living systems. The student is expected to identify feedback mechanisms that maintain equilibrium or systems such as body temperature, turgor pressure, and chemical reactions
Lesson Objectives
The learner will produce a graph or sketch to describe a negative feedback system, such as for serotonin production.
The learner will demonstrate understanding of how blood glucose is controlled in humans by creating labeled drawings and providing a summary of the process.
The learner will produce a labeled sketch that describes thermal regulation in humans.
Question
True or False: Each body system works in isolation
Body systems are interrelated and work through a series of feedback systems
Question
True or False: Feedback systems react quickly
In feedback systems, the action of a system components is typically slow in terms of time. That is, there is a build up in one direction and slowly, the body returns to homeostasis.
Prior Knowledge
Identify human systems and their function
Background
Negative feedback systems – homeostasis
• Control of blood glucose
• Control blood calcium
• Control of blood pressure
• Control of body temperature
Negative feedback
Returns the body to equilibrium. It works like driving car down the road. Constant adjustment to the right or left is required to keep the car on the road.
A negative feedback system is one that tries to keep the body constant.
In a positive feedback system the change will continue to increase in one direction until something happens in the body to stop it.
An example of positive feedback is
childbirth
The feedback cycle
Glucose: Insulin and Glucagon
The receptors of the pancreas are responsible for monitoring glucose levels in the blood.
Blood Glucose Level
• Pancreatic Hormones regulate blood sugar level before and after meals.
• Islets; clusters of cells in pancreas– Alphasecrete GLUCAGON – increases sugar– Beta secrete INSULIN – decreases sugar
What Happens?
• Between meals Blood glucose lowPancreas secretes
glucagonLiver changes glycogen to glucoseglucose sent to target tissues
• After a meal Blood glucose highPancreas secretes
insulinGlucose goes to the Liver(Glygogen) and goes to Target tissues
Fight or Flight
In emergencies, adrenaline is released by the body to override the homeostatic control of glucose. This is done to promote the breakdown of glycogen into glucose to be used in the emergency. These emergencies are often known as 'fight or flight reactions'.
Fight or Flight
Adrenaline is secreted by the adrenal glands. The secretion of it leads to increased metabolism, breathing and heart rate. Once the emergency is over, and adrenaline levels drop, the homeostatic controls are once again back in place
Thermoregulation
The Search for Answers
ENGAGE
View the video clip, “The Search for Answers” beginning at 2:50.
Compare the level of serotonin and serontonin receptors. Stop the video at 3:50, 3:56, and 4:03
EXPLORE
1. What is the role of serotonin?2. What is the effect of high levels
of serotonin on the body?3. Explain how the body attempts to
regulate serotonin levels?4. Relate serotonin regulation to
anorexia nervosa.
EXPLAIN
Role Play: The Rise and Fall of Glucose
ELABORATE
How does the body keep from overheating?
How does the body keep warm?
ELABORATE
1.Produce a sketch or graph and describe a negative feedback system.
2.Produce a labeled sketch of thermal regulation in humans.
3.Summarize the regulation of blood glucose
EVALUATE
regulates
Concept Map
by meansof the
by meansof the
by meansof the
by meansof the
by meansof the
by meansof the
GrowthWater
balanceReproduction Metabolism
Calciumand glucose
levels
Responseto stress
The Endocrine System
Pituitary
Ovaries
Testes Thyroid Pancreas Adrenals
Parathyroids
