Kinesology 2Y03 - Homeostasis - Module 2

Homeostasis

The existance and maintinace of a relativly constant environment within the body.

or

The ability or tendency of an organism or cell to maintain internal equilibrium by adjusting its physiological processes.

Normal Values???

Set Point

• Values of variables fluctuate around a set point to establish a NORMAL RANGE of values

Role of Organ Systems

• Help control internal environment

• Communication between cells, tissue, organ systems is important

CRUCIAL ROLE:

• Nervous system

• Endocrine system

  • These two gather sensory info from internal/external environment

    • then send out signals to body systems to make adjustments

      • that try to return the body to homeostasis

Feedback Systems

1. Receptor

Monitors the value of some variables (Ex: Red Blood Cell Blood Pressure Monitoring cell)

2. Control Center

Establishes set point (e.g., brain)

3. Effector

Can change the value of the variable (usually an organ)

Stimulus

• Causes deviation from set point; detected by receptor

Response

• Produced by effctor to try and provide homeostasis

Negative Feedback

• Any deviation from the set point is made smaller

  • Resisted

Ex: (blood Pressure, Body temp, blood Sugar levels)

Most feedback loops are negative

Positive Feedback

• When deviation happens the response is to make it greater

  • Unusual in Normal, healthy individuals

  • Leads away from homeostasis

    • CAN DIE

Not always bad:

Does Deviation Always Trigger Feedback??

No

- Ranges can change → Temporary Normal

Ex: BP during excersize

• As exercise continues + elevates BP rises

  • Increase Blood flow required

Consequenses of Homeostasis Distruption

1. A disease state

Ex; Blood Sugar levels not maintianed at regular levels → Diabetes

Twin Ex: one twin growing at much faster rate than other

• Larger twin had tumor on pituitary gland