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

http://www.pbs.org/wgbh/nova/thin/program.html

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