Sponge: When we say that the body

demonstrates homeostasis, do we mean that conditions in the body are unchanging? Explain in your own words in 2-3

sentences…

Agenda

Sponge (10) Quiz make up policy (5) Notes: What is homeostasis? (20) LS assignment: Circle Maps (20) Organ system work time (20) Exit Pass (10)

Reminders: Organ systems project due Monday Unit 1 Test and Notebook check Tuesday

Standards Mastery

SAP1c- Homeostasis

SAP1c. Explain the role of homeostasis and its mechanisms as these relate to the body as a whole and predict the consequences of the failure to maintain homeostasis.

Quiz Results! 2nd block Average 75%

Quiz Makeup policy

Question Number:___ GPS Standard:__________ Vocabulary + definitions needed to

understand the question (at least 3 words): 1. ________________________- 2. _______________________- 3. ________________________- Why did you miss this question? What is the correct answer? _______

HOMEOSTASIS!!

What is homeostasis?

• Homeostasis is the state of equilibrium of the internal environment of the body. Homeostasis is maintained by the dynamic processes of feedback and regulation.

– Homeo = same

– Stasis = standing still

What is homeostasis?

•So, Homeostasis means unchanging, but it is actually a dynamic equilibrium. Dynamic equilibrium means that internal conditions change and vary within narrow limits.

– Homeostasis is basically the body's natural desire to remain unchanged.

All homeostatic mechanisms have three components

1. Receptor2. Control Center 3. Effector

How does Homeostasis work?

1.Receptor –monitors and responds to changes in the environment. Responds to stimuli by sending information (input) into the control center.

– Afferent pathway = Receptor to control center

2. Control Center – controls the level the variable is supposed to be at, analyzes the situation and determines the appropriate action.

2. Control Center– Efferent pathway = control center to

effector3. Effector – Provides the output of the control center. Determines which mechanism to use.

The two feedback systems: Positive Feedback System Negative Feedback System

Positive Feedback System

Positive Feedback- when the initial stimuli cause an increasing reaction from the organism, it is a cascading reaction.

– Each reaction from the organism is stronger than the last.

– Ex: Oxytocin in child birth

Negative Feedback System Negative Feedback- The body has a set

range of internal conditions. When the body is not in these optimal conditions the organism will respond and reactions will occur to get the person back to the range of normalcy.

– This type of feedback is similar to a thermostat.

– This is the more common type of feedback mechanism found in living organisms.

– Ex: Heart Rate, temperature

Quick Check:

What does the afferent pathway connect? Receptor and control center.

How does the positive feedback system work? Each reaction builds on the

previous

LS Assignment

Create two circle maps defining Positive Feedback System and Negative Feedback System

In your outer circle include defining words, phrases, and pictures.

CWP Frame of reference: What are the three

components of all homeostatic mechanisms. How are these three components connected and what do they do?

Exit FUN

1. What is the control center and how is it connected to the receptor and the effector?

2. What is an example of a negative feedback system?

Homeostasis Lab:

1. Read through the entire lab.2. Pick one person on your team to conduct

the physical activity. 3. Only one classmate will be recording

temperature, and you will be able to record the data into your own Lab sheet.

4. When you are finished… see right white board.