Heart 
3 main functions:
1. Pump
Right atrium and ventricle >>> transport blood (deoxygenated) to lung for gases exchange
Left atrium and ventricle >>> transport blood (oxygenated) from lung to whole body
2. origin of the circulatory system ( conducting system )
-origin of the circulatory system with electrical cells (10% myocardial cell) with automaticity to stimulate myocardial cell contract regularly for pumping
- SA node
- AV node
- Bundle of His
- Purkinje fibers
3. Endocrine
heart secret peptide hormone for BP control (under the regulation of nervous system/ hormones)
Blood pressure (BP) 血壓
Blood pressure = Total Peripheral Resistance x Cardio Output
sBP (systolic blood pressure) = 收縮壓(俗稱上壓），是指心臟收縮時的血壓 (90-120mmHg)
dBP (diastolic blood pressure) = 舒張壓(俗稱下壓），心臟舒張時血液回流進 (60-80mmHg)
Circulatory system 循環系統
Heart = powerhouse in the system
Artery= carry blood to tissue
Vein = carry blood to heart
Lymphatic vessel = absorpt fluid leave from blood vessel
**blood vessel = artery, vein, capillary**
2 main parts:
-body circulatory system
-pulmonary circulatory system
Blood
Components:
1. Plasma 血漿 = carry blood cells, nutrient, protein, water, salts and metabolic waste etc.
2. Blood cells (3types) = RBC (red blood cell, transport O2), WBC ( white blood cell for immunity), platelet ( with thrombin to stop bleeding)
Blood groups (血型)
ABO group
| A型 | B型 | AB型 | O型 | |
| antigen | antigen A | antigen B | antigen A+B | no antigen |
| antibody | antibody B | antibody A | no antibody | antibody A+B |
|
can take A & O |
can take B & O |
universal recipient |
universal donor only take O blood |
Rh group
Rh +ve = with Rh factor
Rh -ve = with Rh antibody
i.e. 正型血者可接受負血型的血，但負血型者只可輸負血型
e.g. AB blood type with Rh+ = AB+ = universal recipient (can take any blood types)
**HK99%人屬正型血，只有極少數屬負型**
O- 的血液被譽為救急時的至寶，因為它屬於Universal Donor，即可以輸送給任何血型的病人。故在最危急之時，如未及為病人作血型配對，O負型的血液便成為了救人的關鍵。
但十分諷刺地，屬O負血型的人，當自己需要接受輸血時，只能接受O負型的血液。可惜，O負血型屬於甚為少見的一種，平均一百人中只有大概一至五人屬此血型。
Body fluid 體液
1. Electrolyte Balance (pH)
| metabolic acidosis<7.35 |
metabolic alkalosis >7.45 |
| s/s | s/s |
| loss of conscious, coma | irritation, irritability |
| convulsion | muscle tonic spasm |
| ↓HR, ↓BP | ↑HR , ↓BP |
| N&V | N&V |
| deep breathing | shallow and slow breathing |
2. Body fluid delivery mechanism
Osmosis, by opposite pressure between H.P. and C.O.P to regulate the flow of body fluid and substance
1. Hydrostatic Pressure (H.P.) > largest in arterial end to force liquid out of blood vessels
2. Colloidal Osmotic Pressure (C.O.P.) > largest in venous end to pull liquid back to blood vessels
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