Circulatory system

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Circulatory system
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General outline
Heart Arteries Capillaries veins
Blood vascular system
Lymphatic capillaries Lymphatic vessel Lymphatic
ducts
Lymphatic vascular system
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Capillaries
A single layer of endothelial cells basement
membrane A few connective tissue (pericytes)

• LM

Continuous capillary Fenestrated
capillary Sinusoid

• EM

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Capillaries
Continuous C.
Fenestrated C.
Sinusoid
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Continuous capillary

• distributed in muscle tissue, brain, lung and
• connective tissue, etc.
• endothelial cell large number of pinocytotic
• vesicles, no pores, exist cell junctions
• between the endothelia
• basement membrane integrity

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Continuous capillary
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Fenestrated capillary

• distributed in the kidney glomerulus, mucosa
• of gastrointestine, some endocrine glands
• endothelial cells present abundant pores, have
• or havent diaphragm on them
• basement membrane continuous

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Fenestrated capillary
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Sinusoid

• distributed in liver, spleen, and some
• endocrine glands
• a greatly enlarged diameter
• endothelial cell intercellular clefts are large
  
• between cells, many pores without diaphragm
• absence of a continuous basement membrane

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Sinusoid
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Artery

• transport blood from heart to capillaries
• according to their size, structure
• and function

Large artery Medium-sized artery Small
artery arteriole
are classified
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Medium-sized artery

• muscular artery

Endothelium Subendothelial layer LCT Internal
elastic lamina clear
Tunica intima
Tunica media contain 1040 layers of circular
smooth muscle
External elastic lamina LCT contain vasa vasorum
Tunica adventitia
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Medium-sized artery
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Large artery

• elastic artery
• subendothelial layer is thicker with a few
• smooth muscles
• tunica media is thick, contains a lot of
  circular
• elastic membrane
• internal and external elastic lamina are not
• distinguished
• tunica adventitia are thiner

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Large artery
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Small artery

• muscular artery and peripheral resistance
• vessel
• internal elastic lamina is clear, while
• external elastic lamina is not distinguished
• the media contains 39 layers of smooth
• muscles

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Vein

• large lumen, thin wall, irregular
• internal and external elastic lamina are not
  clear
• tunica media is thin, with a few elastic fibers
  and
• smooth muscles
• tunica adventitia is thick
• some veins have valves

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Heart

• a muscular organ that contracts
• rhythmically
• pump blood through the circulatory
• system

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The wall of heart
Endothelium Subendothelial layer Subendocardial
layer

• endocardium

• myocardium thickest layer, consists of

cardiac muscle
LCT contain adipose tissue Methothelium

• epicardium

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Impulse generating and conducting system of the
heart

• Pacemaker cells heartbeat generating
• Purkinje cells (bundle cell)

distributed in subendocardial layer, larger than
cardiac muscle cells

• Transitional cells transmit impulse

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Purkinje cell
Cardiac cell