1. Life Processes Metabolism Responsiveness Movement Growth
Differentiation
Reproduction

2. Survival Needs Appropriate body temperature Atmospheric pressure
Must be kept within a certain range for proper breathing and cellular metabolism
Nutrients
Needed for energy and building cells
Oxygen
Required for the breakdown of nutrients
Water

3. Homeostasis
Ms Clark
PVMHS

4. Homeostasis
The body’s ability to maintain relatively stable internal conditions despite changes inside and outside of the body

5. Every body structure has one or more homeostatic devices that works to keep the internal environment within normal limits.
Homeostatic mechanisms are mainly under the control of the nervous system and the endocrine system.

6. Homeostasis and the Nervous System
Detects changes from balanced state Sends message in the form of nerve impulses to organs that can counteract change Organ reacts

7. Afferent vs Efferent
AFFERENT neurons are responsible for sending information about the stimulus to the central nervous system
EFFERENT neurons carry signals away from the central nervous system in order to initiate an action

8. Example
Body temperature rises above normal level Nerve impulses cause sweat glands to release more sweat Body cools as sweat evaporates

9. Homeostasis and the Endocrine System
Endocrine system corrects changes by secreting hormones into the blood Hormones target specific body cells where they cause responses that restore homeostasis

10. Example
Blood glucose level is too high The hormone insulin is secreted and reduces blood glucose level

11. Nerve impulses typically restore homeostasis more rapidly than hormones

12. Feedback System
A cycle of events in which the status of a body condition is continually monitored, evaluated, and changed.
Each monitored condition is called a controlled condition
Ex: Body temperature, blood pressure, blood glucose level

13. Stimulus: any disruption that causes a change in a controlled condition
Ex: Extreme heat, lack of oxygen, low blood glucose level

14. Components of a Feedback System
Receptor
Monitors changes, sends input to a control center
Ex: temperature-sensing nerve endings in skin
Control Center
Sets the range of acceptable values for a body condition, generates output to effector
Ex: brain
Effector
Receives output and generates a response
Ex: skeletal muscles

15. Types of Feedback Systems
Negative Feedback System
Reverses the original stimulus
Ex: Restoring body temperature through production of sweat
Positive Feedback System
Enhances or intensifies original stimulus
Ex: Contractions during childbirth
Ex: Blood clots

16. Negative Feedback System
Stimulus disrupts homeostasis
Condition monitored by
Return to homeostasis
Response
Effectors
Receptors
Control Center
Input
Output

17. Positive Feedback System
Platelets adhere to wound site
Released chemicals attract more platelets

18. Homeostasis & Disease
As long as homeostasis is maintained, the body stays healthy
If a component of the body loses its ability to contribute to homeostasis, balance among all body processes may be disturbed
If homeostatic imbalance is moderate, a disorder or disease may occur
If it is severe, death may result.

19. Homeostasis & Disease Disorder Disease Any abnormality of a function
Ex: Heart disorder, OCD
Disease
An illness characterized by a recognizable set of signs and symptoms
Ex: Heart disease, flu

20. Diseases/Disorders
Acute: affects a person for a certain amount of time; usually temporary
Ex: heart attack
Chronic: remain for a long time and can get worse; usually no cure
Ex: atherosclerosis (heart disease)

21. Symptoms
Subjective changes in body functions that are not apparent to an observer
Ex: Headache, nausea
Signs
Objective changes that someone can observe and measure
Ex: Bleeding, swelling, fever, rash