Maintenance of a STABLE internal environment

NEGATIVE FEEDBACK - the main mechanism of homeostasis

Requires most of our metabolic energy

1) Receptors - provide information about specific conditions (stimuli) in the internal environment - molecule or cell.

2)  Control Center - Includes a set point - tells what a particular value should be (Body Temp. 98.6)

3)  Effectors - Such as muscles or glands, which elicit responses that alter conditions in the internal environment

4)  Response

Stimulus (room temp. decreases) - Receptors (thermostat detects change) - Control Center (thermostat detects deviation from set point and signals effectors) - Effectors (heater turns on and air off) - Response (room temp. returns to set point)

Stimulus (Body temp. drops below normal) - Receptors (Thermoreceptors send signals to control center) - Control Center (The hypothalamus detects the deviation from the set point and signals effector organs) (If body temp. continues to drop, control center signals muscles to contract voluntarily) - Effectors (skin blood vessels constrict and sweat glands remain active - muscle activity generates body heat) - Response (body heat is conserved - temp. rises toward normal)

CALLED PERITONEAL MEMBRANES

PARIETAL PERITONEUM - Lines wall of abdominopelvic cavity

VISCERAL PERITONEUM - Covers most of the organs in the abdominopelvic cavity

PERITONEAL CAVITY - Potential space between the membranes

PARIETAL PLEURA

VISCERAL PLEURA

Serous fluid between the membranes.  The potential space between is called pleural cavity.

1)  Surround Heart

2)  Visceral pericardium covers heart's surface

3)  Parietal pericardium is covered by thicker layer - fibrous pericardium

Pericardial Cavity

SEROUS MEMBRANES

VISCERAL MEMBRANES

PARIETAL MEMBRANES

Thin and secret watery fluid

Serous membranes that cover organ surfaces

Serous membranes that line cavities