循環生理

黃基礎1998, 10, 23

Design of circulatory system

• Three essential components: 1. blood: circulatory fluid 2. vascular system : through which the fluid can circulate 3. a heart: to pump the blood

• Two type of circulatory system 1. open circulatory system 2. closed circulatory system

Two types of circulatory system

• Open circulation 1.hemolymph 2.hemolymph was circulated into hemocoel 3. Hemocoel is large, constitued 20-40% of body weight. Blood vol is about 30% of body volume 4. Low pressure

• Closed circulatio 1. Blood 2. Blood was circulated through vessels: artery, capillaries, vein 3. Blood vol is about 5-10% of body volume 4. High pressure arterial pres and pul pres

Two types of circulatory system

• Open circulation 5. Pulsaltile vessel to propel hemolymph 6. Velocity and distribution of blood flow is limited.

• Closed circulatio 5. Heart contraction to pumpb blood 6. Capillary walls are thin. Oxygen delivery to tissure rapidly. 7. Ultrafiltration occur in the kidney to separate the fitrate from plasma. 8. Lymph system to recover the fluid lost

The Heart • Cardiac muscle

• Electrical activity of the heart

• Pacemaker potential

• Ionic mechanism of cardiac action potential

• Electrocardiogram

• Heart rate

• Cardiac output and venous return

• Cardiac cycle

Cardiac muscle

Cardiac muscle

• Intercalated disk between cardiac cells

• Gap junction let ions flowing from cell to cell

• syncitiun

Conducting system

• Sinoatrial node (SA node) or Pacemaker

• Atrioventricular node (AV node)

• His bundle• Purkinje fibers

Electrical activity of the heart

Electrical activity of the heart

• There are two types of cardiac action potential

• the slow action potentail and

• the fast action potential

Ionic mechanism of the fast action potential

• Occurs in the following cells: 1.Purkinje fibers 2.Atrial cells 3.ventricular cells 4.His bundle

Ionic mechanism of the slow action potential

• Seen in the following cells

• sinus node (sinoatrial node; SA node; or pacemaker)

• atrioventricular node (AV node)

Electrocardiogram

Electrocardiogram

Heart rate:

Sympathetic nerve

Parasympathetic nerve

Heart rate

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