what do you need to survive right now? homeostasis!

What do you need to survive right now?

Homeostasis!

Today’s GoalsDescribe most basic needs to live right now

(you probably know 4/5)Describe homeostatic mechanisms to

maintain homeostasis

Tonight – start practicing directional terms

Survival NeedsNutrients – needed for energy and cell building

Oxygen – necessary for reactions

Water – provides the necessary environment for chemical reactions

Survival NeedsNormal body temperature – necessary for chemical reactions to occur at life-sustaining rates

Atmospheric pressure – required for proper breathing and gas exchange in the lungs

HomeostasisHomeostasis – ability to maintain a relatively stable internal environment in an ever-changing outside world

The internal environment of the body is in a dynamic state of equilibrium

Homeostatic Control MechanismsVariables produce a change in the body

three interdependent components of mechanisms:Receptor – monitors the environments and responds to changes (stimuli)

Control center – determines the set point at which the variable is maintained

Effector – provides the means to respond to stimuli

Homeostatic Control Mechanisms

Figure 1.4

Variable (in homeostasis)

Homeostatic Control Mechanisms

Figure 1.4

Stimulus: Produces changein variable

Variable (in homeostasis)

Imbalance

Imbalance

1

Homeostatic Control Mechanisms

Figure 1.4

Change detected by receptor

Stimulus: Produces changein variable

Receptor (sensor)

Variable (in homeostasis)

Imbalance

Imbalance

2

1

Homeostatic Control Mechanisms

Figure 1.4

Change detected by receptor

Stimulus: Produces changein variable

Input:Informationsent along afferentpathway to

Receptor (sensor)

Controlcenter

Variable (in homeostasis)

Imbalance

Imbalance

2

3

1

Homeostatic Control Mechanisms

Figure 1.4

Change detected by receptor

Stimulus: Produces changein variable

Input:Informationsent along afferentpathway to

Receptor (sensor) Effector

Controlcenter

Variable (in homeostasis)

Output:Information sentalong efferentpathway to

Imbalance

Imbalance

2

34

1

Homeostatic Control Mechanisms

Figure 1.4

Change detected by receptor

Stimulus: Produces changein variable

Input:Informationsent along afferentpathway to

Receptor (sensor) Effector

Controlcenter

Variable (in homeostasis)

Response ofeffector feedsback toinfluencemagnitude ofstimulus andreturns variableto homeostasis

Output:Information sentalong efferentpathway to

2

34

5

1

Feedback loopsNegative Feedback Loops

Positive Feedback Loops

Results in turning off cause or stimulus

Most Common

Enhances Stimulus or Cause

Negative feedback loopExamples

Eat, Blood Sugar rises, Insulin released, tells cells to take in glucose, blood sugar levels drop and insulin release is dropped

Blood volume drops, release ADH absorb more water

Hormonal MechanismCa2+ levels go UP (and they stay there) trigger the thyroid to release calcitonin

Calcitonin stimulates calcium

salt deposit in bone

Positive feedback loopsexamples Oxytocin and delivering the baconBaby needs milk Oxytocin