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Name and describe the three layers (tunics) of the heart
- 1) Endocardium: glistening layer (smooth); simple squamous epithelium; subendothelial CT (elastin fibres); conduction system of the heart
- 2) Myocardium; cardiac muscle connected end to end using intercalated discs; rich in capillaries;
- 3) Epicardium: visceral layer of the pericardium; serous membrane, mesothelium, lots of elastic fibres. nerves and coronary arteries
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Unique characteristics of cardiac myocytes
- -striation less powerful
- -central nucleus
- -intercalated discs
- -juxtanuclear region
- -intrinsically capable of contraction
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Name and describe the three layers of blood vessels
- 1) Tunica Intima: endothelium, basal lamina, loose CT
- 2) Tunica media: circumferentially arranged smooth muscle, produce their own matrix
- 3) Tunica adventitia: connective tissue, merges with surrounding connective tissue.
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Name the seven types of blood vessels
- elastic artery (aorta)
- muscular artery
- arteriole
- capillaries
- venules
- veins
- vena cava
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Describe the three layers in elastic arteries
- Intima: endothelium with BL, subendothelium CT
- Media: fenestrated elastic sheaths, smooth muscle
- adventitia: vasa vasorum and nervi vasorum
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Describe the three layers in a muscular artery
- intima: endothelium and BL; subendothelial CT (includes IEL)
- media: LOTS of smooth muscle; external elastic lamina
- adventita: CT and vasa vasorum
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Describe the three layers in arterioles (resistance vessels)
- intima: endothlium and BL, less elastic tissue
- media: 1-2 layers of smooth muscle
- adventita: thin
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describe the three layers in capillaries
- intima: endothelium and BL; +/- pericytes
- media: none
- adventitia: none
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What are the three type of capillaries?
- 1) continuous enothelial: found in most tissues (lung, muscles, etc)
- 2) fenestrated: epethelial cells have fenestrations but BL is intact, found where these is extensive exchange with the blood (e.g. intestines, kidneys)
- 3) discontinuous: gaps in both basal lamina and endothelial cells, not common, liver, spleen, etc
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describe the three layers of venules
- intima: endothelial cells and BL, +/- pericytes
- no media or adventitia
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describe the three layers in veins (capacitance vessels)
- intima: endothelium and BL, loose CT under this
- media: smooth muscle (irregular orientation)
- adventitia: CT
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describe the three layers in the vena cava
- intima: endothelium and BL, underlying CT
- media: smooth muscle
- adventita: CT, some elastic tissue, longitudinal smooth muscle
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Describe the structure and function of arteriovenous anastomoses
- Direct link from arteriole to vein
- artery has very thick muscular walls
- under sympathetic control
- when the muscle contracts it forces blood through the capillary bed
- one use is for thermoregulation
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Describe the structure and function of metarterioles
- a larger "capillary" with isolated SM in its walls
- acts as a throughfare between arterioles and venules
- contraction of SM forces blood to flow through the capillary bed
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What is a glomus body?
- An ateriovenous anastonomis with a CT capsule
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What are the six functions of epithelial cells
- as epithelium: barrier
- produce vasoactive substances (e.g. vasodilators)
- participate in the control of blood coagulation
- proliferate in response to signals (e.g. VEGF)
- mediate interactions with leukocytes (diapodesis)
- lipoprotein metabilism
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describe the three layers in a lymphatic capillary
- intima: discontinuous endothelial with no basement membrane
- no media, adventitia (does have anchoring filaments), or pericytes
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How do you distinguish a larger lymphatic vessel from a vein
- -have more valves
- -lymph and not rbcs in the lumen
- -thinner wall with larger lumen
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describe the cross section of the thoracic duct
- -tunica intima: endothelial lining; fibroelastic tissue; inner elastic lamina
- -fibromuscular wall
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