Physical & chemical properties of blood
1. Specific Gravity（比重）
Depending on hematocrit & protein composition
Whole blood：
1.050~1.060
Plasma：
1.025~1.035
Red blood cells：
4. Plasma pH
Normal range: 7.35~7.45 Buffer systems（缓冲系统）:
Hematocrit（packed cell volume, 血细胞比容）
the volume of red blood cells as a percentage of centrifuged whole blood
M: 40~50% F: 37~48%
International Council for Standardization in Haematology (ICSH) Recommendations for "Surrogate Reference" Method for the Packed Cell Volume
BLOOD【血液】
Internal environment （内环境）
Body Fluid = 60% of Body Weight (BW)
Extracellular Fluid 1/3, 20% of BW
Plasma 5% of BW
Interstitial Fluid 15% of BW
Intracellular Fluid 2/3, 40% of BW
Digestive system Urinary system
Nervous system Endocrine system
Lymphatic system Reproductive system
Components of blood
Plasma（血浆） Blood Cells
Red Blood Cells (RBC) or Erythrocytes（红细胞） White Blood Cells (WBC) or Leucocytes（白细胞） Platelets (PLT) or Thrombocytes（血小板）
Plasma includes water, ions, proteins, nutrients, hormones, wastes, etc.
The hematocrit（血细胞比容） is a rapid assessment of blood composition. It is the percent of the blood volume that is composed of RBCs (red blood cells).
70 kg Male, 42 L
Homeostasis（稳态）
Homeostasis (from the Greek words for “same” and “steady”):
maintenance of static or constant conditions in the internal environment
Plasma osmotic pressure (~300 mOsm/L） Crystalloid Osmotic Pressure（晶体渗透压）
Pressure generated by all crystal substances, particularly electrolytes
Important in maintaining fluid balance across cell membranes
1.090
2. Viscosity（粘度）
relative viscosity of whole blood 4~5 depending on hematocrit
relative viscosity of plasma 1.6~2.4 related to the protein composition of the plasma
3. Osmotic Pressure（渗透压）
The osmotic pressure of a solution depends on the number of solute particles in the solution, NOT on their chemical composition and size
How is homeostasis achieved?
----Regulation
Body's systems operate together to
maintain homeostasis:
Skin system
Skeletal y system Respiratory system
Colloid Osmotic Pressure（胶体渗透压）
Osmotic pressure generated by plasma proteins, particularly albumin.
Approximately 25 mmHg, but important in fluid transfer across capillaries
Walter B. Cannon
http://www.harvardsquarelib /unitarians/cannon_
walter.html
Components of Homeostasis:
Concentration of O2 and CO2 pH of the internal environment Concentration of nutrients and waste products Concentration of salt and other electrolytes Volume and pressure of extracellular fluid