0206 - Le millieu interieur - EG

Question 1

What is the “milieu interieur”?

Answer 1

The extracellular fluid which bathes every living cell, the constant replenishment and circulation of which is essential for the continued life of cells.

Question 2

What is homeostasis?

Answer 2

“homeo” from the Greek “Homoios” meaning “like” and “stasis” from the Greek meaning of “standing”. Defined as the tendency for stability in the normal body states (internal environment) of the organism. it is achieved by a system of control mechanisms activated by negative feedback.

Question 3

Who said:”The constancy of the internal environment is the condition for a free and independent life”and how did this person come to this statement?

Answer 3

Claude Bernard, 1878Stated from vitro animal experiments where he realised that each time he changed the environment of the animal there was a response to bring the environment back to its normal conditions.

Question 4

Who termed homeostasis in the phrase:”…coordinated physiological processes which maintain most of the steady states… I have suggested a special designation … homeostasis.”

Answer 4

Walter Cannon 1932

Question 5

Core body temperature is kept via homeostatic mechanisms between 36-37.4 degrees Celsius. How is this achieved?

Answer 5

1. Thyroid hormones set a base metabolic rate of cells which generates heat.2. blood vessels in the skin will constrict or dilate to retain or lose heat via radiation, respectively.3. Sweat glands will release sweat so heat will be lost through evaporation.4. Piloerection of hair muscles in skin will cause goose bumps to trap air around the skin and prevent heat loss

Question 6

Why do we study disorders of homeostasis?

Answer 6

It is the basis of the practice of medicine.