what do you need to survive right now? homeostasis!
TRANSCRIPT
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
