The Cell and General Physiology

Homeostatic Mechanisms
Essentially all the organs and tissues of the body perform functions that help to maintain the constituents of the extracellular fluid relatively consistent, homeostasis.

Extracellular transport system - Circulatory system Two stages - around the circulatory system and between the capillaries and the cells. Blood in the capillaries allows exchange between the cells and the interstitial fluid.


Origin of Nutrients in the Extracellular Fluid.  
The respiratory system provides oxygen and removes carbon dioxide.
The gastrointestinal system digests food and absorbs nutrients into the extracellular fluid.
The Liver changes the components into usable form, and other tissue (fat cells, kidneys and endocrine glands) help modify the absorbed substances or store them till needed.
The musculoskeletal system protection and support.


Removal of metabolic End Products
Kidneys regulate the extracellular fluid composition by controlling excretion of salts, water and waist of cellular metabolism. Also regulate fluid volume and blood pressure.


Respiratory system Removes carbon dioxide.

Regulation of Body Functions  
Nervous system Direction and control
Endocrine glands secrete hormones that control and regulate cell function - growth, metabolic rate, reproduction.
Immune System Protection
Integumentary system Skin, external protection, dehydration, body temperature.

Reproduction
Promotes progeny

Control of respiration and Oxygen regulation as a system of control in the body. Negative Feedback is most common. Increased CO2, increases ventilation, which decreases CO2 to normal levels.


GAIN = correction/Error. The degree of effectiveness with which a control system maintains consistant conditions is determined by the gain in negative feedback. Compute GAIN = Correction / Error. A gain of 
-33, simply means that the correction is 33 times greater than the remaining error. 


 Feed-Forward control systems anticipate changes. 
Anticipatory action and muscle movement, then reviewed by the brain, then corrected. The brain corrections are then adaptive control. 


Automaticity  of the Body: The reciprocal social interaction of all cells to positively contribute to homeostasis is automaticity of the body till one or more functional systems loose their ability to their share of homeostasis. 


Normal ranges of constituents and Characteristics of the Extracellular Fluid.
Oxygen            40mmHg (35-45mmHg)
CO2                40mmHg (35-45mmHg)

Na+                 142 mmol/L (138-146 mmol/L)

K+                      4.2           (3.8-5 mmol/L)

Ca2+               1.2 mmol/L  (1.0-1.4 mmol/L)
Cl-                   108 mmol/L (103-112 mmol/L)
HCO3-              28 mmol/L (24-32 mmol/L)
G                        85 mmol/L (75-95 mmol/L)
Body Temp        37 (98.4F) (
Acid Base           7.4  (7.3-7.5)