Lecture 3 Homeostatis

8/14/2019 Lecture 3 Homeostatis

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Organ system inter-relationship

Necessary Life Functions

Survival NeedsHomeostasis

Homeostasis control Mechanism


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OrganOrganSystemsSystemsInterrelationshipsInterrelationships

The integumentary system protects the bodyfrom the external environment

Digestive and respiratory systems, in contact

with the external environment, take innutrients and oxygen.

Nutrients and oxygen are distributed by the

blood

Metabolic wastes are eliminated by the

urinary and respiratory systems


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Necessary Life FunctionsNecessary Life Functions

Maintain Boundaries The internal environment remains distinct from

the external environment, eg

Cellular Level plasma membranes Organism Level skin

Movement

Locomotion

Movement of substances


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Responsiveness

Ability to sense changes in theenvironment and respond to them.

DigestionBreak-down and delivery of nutrients

Metabolism all the chemical reactionsthat occur within the body

Production of energy

Making body structures


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Excretion Elimination of waste from metabolic

reactions

Reproduction Production of future generation

Growth

Increasing of cell size and number


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Survival NeedsSurvival Needs

Nutrients

Chemicals for energy and cell building

Includes carbohydrates, proteins, lipids,vitamins, and minerals

Oxygen

Required for metabolic reactions


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Survival NeedsSurvival Needs Water

6080% of body weight

Provides necessary environment formetabolic reactions

Stable body temperature

Necessary for metabolic reactions to occur

at life sustaining rate Atmospheric pressure

Required for normal breathing and gas

exchange in lungs


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HomeostasisHomeostasis

Maintenance of a stable internal environmentin an ever changing out side world

The internal environment of the body is in a

dynamic state of equilibrium Homeostasis must be maintained for normal

body functioning and to sustain life

Homeostatic imbalance a disturbance inhomeostasis resulting in disease


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Maintaining HomeostasisMaintaining Homeostasis

The body communicates through neuraland hormonal control systems to maintainhomeostasis.

The three interdependent components ofcontrol mechanism include:

1. Receptor

2. Control Center

3. Effector


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1- Receptor Monitors the environment and

responds to changes (stimuli)

2- Control centerDetermines set point at which variable is

maintained.

Analyzes information

Determines appropriate response

3- Effector

Provides a means for response to the stimulus


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Feedback MechanismsFeedback Mechanisms

Negative feedback Positive feedback

Negative feedback

Includes most homeostatic controlmechanisms

Shuts off the original stimulus, or reducesits intensity

Works like a household thermostat


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Negative feedback

Most body systems

regulate Via this

mechanism, eg

Regulation of BloodPressure

Removal of CO2 from

body


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Feedback MechanismsFeedback Mechanisms

Positive feedback

Increases the original stimulus to push thevariable farther

In the body this only occurs in blood clotting

and birth of a baby


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Positive feedback

Blood Clotting Cascade

Lecture 3 Homeostatis

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