1. TOPIC 1 L4. Maintaining life. Homeostasis

2. Maintaining Life
What are the necessary life functions for maintaining life?
Maintaining boundaries - skin
Movement – walking, swimming, running
Responsiveness – sense changes or stimuli in the environment
Digestion – breaking down food into molecules
Metabolism – all chemical reactions that occur in the body cells
Excretion – removal wastes from body
Reproduction – production of offspring
Growth – increase in size

3. Interrelationships among body organ systems
Maintaining Life
Interrelationships among body organ systems
Protection
Take in nutrients and oxigen
Elimination of wastes
Distribution of nutrients and oxigen to all cells

4. Basic Life Processes Movement Responsiveness Metabolism
Occurs at the intracellular, cellular, organ levels.
Responsiveness
Ability to detect and respond to changes in the internal and external environment.
Metabolism
Sum of all biochemical processes of cells, tissues, organs, and organ systems.

5. Basic Life Processes Digestion Excretion Reproduction Growth
Breaking down ingested food into simple molecules that can then be absorbed into the blood.
Excretion
Removing excreta or wastes from the body. Severeal organ systems participate (Ex: Digestive and urinary).
Reproduction
Formation of new cells for growth, repair, or replacement, or the production of a new individual.
Growth
Increase in number of cells, size of cells, tissues, organs, and the body. Single cell to multicellular complex organism.

6. Maintaining Life What are the survival needs?
Nutrients (food) – needed for energy and cell building
Carbohydrates major energy-providing fuel for cells, proteins and fats.
Oxygen – needed for release of energy from food.
Water – needed for body secretions and excretions (60% to 80% of body weight)
Body temperature (37ºC or 98ºF)
Temp drops, metabolism becomes slower and stop.
Temp too high, metabolism too fast (If extreme, death)
Atmospheric pressure – needed for breathing and exchange of oxygen and carbon dioxide in the lungs.

7. Homeostasis
Describes the body’s ability to maintain relatively stable internal conditions even though the outside world is continuously changing.
The literal translation of homeostasis is “unchanging,”(homeo= the same, stasis = standing still.
The tem does not really mean and unchanging state, instead it indicates a dynamic state of equilibrium.

8. Homeostatic Control Mechanisms
Communication within the body is essential.
Communication is accomplished by the nervous and endocrine systems, using neural electrical impulses or blood borne hormones.
Regardless of the factor being regulated (the variable) all homeostatic control mechanisms have at least three interdependent components.

9. Components
1. Receptor: Sensor that monitors the environment and responds to stimuli, by sending information (input).
2.Control center: Analyzes the input and then determines the appropriate response.
3. Effector: Provides the means of response (output) to the stimuli.
The results of the response then feed back to influence the stimuli, either depressing it (negative feedback), or enhancing it (positive feedback)

10. The elements of homeostatic control system

11. Homeostatic Control Mechanisms
Negative feedback mechanisms – the net effect of the response to the stimulus is the shut off of the original stimulus or to reduce its intensity.
E.g. – body temp, blood chemical levels
Positive feedback mechanisms – tend to increase the original disturbance (stimulus) and push the variable farther from its original value.
E.g. – ovulation, blood clotting, birth

12. Example of a nonbiological negative feedback system: Heating system connected to a temperature-sensing thermostat
Thermostat is set at 20°C (68°F), the heating system (effector) is triggered ON when the house temperature drops below that setting.
Furnace produces heat, warms the air and the temperature rises.
When it reaches 20°C or slightly higher, the thermostat triggers the furnace OFF.
Your body “thermostat,” located in a part of your brain called the hypothalamus, operates in a similar fashion.

13. Homeostatic Imbalance
Inability of the body to restore a functional and stable internal environment.
As we age, our body’s control systems become less efficient, and our internal environment becomes less and less stable.
These events increase our risk for illness and produce the changes we associate with aging.

14. The Language of Anatomy
Special terminology is used to prevent misunderstanding
Exact terms are used for:
Position
Direction
Regions
Structures

15. Anatomical Position
The anatomical position is a standardized method of observing or imaging the body that allows precise and consistent anatomical references.
When in the anatomical position, the subject stands (Figure 1.5).
standing upright
facing the observer, head level
eyes facing forward
feet flat on the floor
arms at the sides
palms turned forward (ventral)

16. Body Landmarks
Anterior
Figure 1.5a

17. Body Landmarks
Posterior
Figure 1.5b

19. Directional terms
Superior (cranial or cephalad) – toward the head end or upper part of a structure or body; above
Inferior (caudal) – away from the head end or toward the lower part of a structure or body; below
Anterior (ventral) – toward or at the front of the body; in front of
Posterior (dorsal) – toward or at the backside of the body; behind
Medial – toward or at the midline of the body; on the inner side of
Lateral – away from the midline of the body; on the outer side of

20. Directional terms
Proximal – close to the origin of the body part or the point of attachment of a limb to the body trunk.
Distal – farther from the origin of a body or the point of attachment of a limb to the body trunk.
Superficial (external) – toward or at the body surface.
Deep (internal) – away from the body surface; more internal.

21. Orientation and Directional Terms

22. Orientation and Directional Terms

23. Examples:
The navel is inferior to the breastbone
The heart is posterior to the breastbone
The arms are lateral to the chest
The elbow is proximal to the wrist
The skin is superficial to the skeleton
The forehead is superior to the nose
The breastbone is anterior to the spine
The heart is medial to the arm
The armpit is intermediate between the breastbone and the shoulder
The knee is distal to the thigh
The lungs are deep to the rib cage

24. Practice The navel is --------------to the breastbone
The heart is to the breastbone
The arms are to the chest
The elbow is to the wrist
The skin is to the skeleton
The forehead is to the nose
The breastbone is to the spine
The heart is to the arm
The armpit is between the breastbone and the shoulder
The knee is to the thigh
The lungs are to the rib cage