Term
| What are the components of the vascular system? |
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Definition
Cardiovascular System
-Heart
-Arteries
-Veins
-Capillaries
Lymphatic Vascular System
-Lymphatic Ducts
-Lymphatic Vessels
-Lymph Nodes
-Lymphatic Capillaries |
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Term
| What are the components of the blood vessel walls? |
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Definition
Tunica Intima - Endothelium (Simple Squamous Epithelium) & Subendothelial Connective Tissue
Tunica Media - Vascular Smooth Muscle
Tunica Adventitia - Fibroelastic Connective Tissue
*adventitia lacks mesothelium layer (simple squamous) that serosa contains. this is an important distinction between the two |
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Term
| What is the structure of a capillary? |
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Definition
Endothelial cells rolled into a tube
Attached by junctional complexes
Surrounded by basal lamina |
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Term
| What are the different functions of endothelial cells? |
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Definition
- Convert Angiotensin I to Angiotensin II(mainly in lungs, enhances arterial smooth muscle contraction). Angiotensin II increases BP thru decreasing the diameter
- Inactivate bioactive compounds to modulate blood flow (bradykinin,serotonin, prostaglandins, norepinephrine, thrombin)
- Lipolysis (metabolizes lipoproteins to mobilize cholesterol & triglycerides for other cell functions)
- Prevent thrombus formation (endothelial damage impairs prostacyclin release and uncovers the basal lamina allowing platelet attachment & activation)
- Capillary transport (exchange of nutrients, oxygen, & wastes between blood & tissues) |
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Term
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Definition
Adventitial cells that cling to outer surface of capillary endothelium
- Enclosed in endothelial basal lamina - used to distinguish from smooth muscle cells in EM and LM
- Contract to reduce blood flow
- Attenuate to enhance permeability
- Function as mesenchymal stem cells |
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Term
| What are the three capillary types? |
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Definition
-Continuous (most; esp. Muscle, Nerve)
- Fenestrated (Diaphragms; Renal Glomeruli)
- Discontinuous /Sinusoids (Liver, Bone Marrow, Spleen, Endocrine Glands) |
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Term
| Explain continuous capillaries |
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Definition
Located in most tissues but especially in muscle and nerve (important part of the blood-brain barrier)
they contain micropinocytotic vessels used to carry things throughout the cytoplasm |
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Term
| Explain fenestrated capillaries |
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Definition
Located in renal glomeruli
Contain fenestrae which are openings in the wall of the endothelium (but still contain complete basal lamina)
The fenestrae along with the diaphragms serve as a filtration system |
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Term
| Explain discontinuous capillaries/sinusoids |
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Definition
Located in liver, bone marrow,spleen, and endocrine glands
Contain fenestrae and incomplete basal lamina
This allows direct contact between blood and tissues (can be but not usually big enough for cells to pass thru) |
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Term
| What are the types of capillary transport? |
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Definition
1. Micropinocytosis (vesicles)
2. Diffusion through fenestrae
3. Diapedesis through intercellular junctions
4. Diffusion across membranes & cytoplasm - example - steroids
5. Diffusion & Diapedesis through endothelial discontinuities |
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Term
| How is capillary development regulated? |
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Definition
Angiogenic Factors
-Tissue Hypoxia
-Vascular Endothelial Growth Factor (VEGF)
-Fibroblast growth factors (FGFs)
-Interleukin-8 (IL-8)
Antiangiogenic Factors
-Thrombospondin
-Tumor Necrosis Factor (TNF)
-Tissue Inhibitors of Metalloproteinases (TIMPs) |
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Term
| What are the four types of arteries? |
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Definition
Descending in size
Large Elastic Arteries
Muscular Arteries
Arterioles
Metarterioles |
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Term
| What are the characteristics of large elastic arteries? |
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Definition
Largest arteries in the body (ex - aorta)
Conduct blood away from the heart and important in maintaining pressure and power from ventricular contraction
- during contraction (systole) artery stretches
- during relaxation (diastole) artery recoils (contracts)
Tunica media is the thickest layer but tunica intima is also thicker than in smaller arteries. Tunica adventitia is thin |
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Term
| What are the characteristics of muscular arteries? |
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Definition
Medium sized arteries
Contain two elastic lamina - the internal elastic lamina that surrounds the tunica intima and the external elastic lamina that surrounds the tunica media
The tunica intima is very thin
tunica media is thick and contains many layers of smooth muscle
tunica adventitia is relatively thin |
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Term
| What are the characteristics of arterioles? |
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Definition
They are small arteries
Tunica intima often lack elastic lamina
The tunica media consists of 1-5 smooth muscle layers.
Tunica adventitia is very thin |
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Term
| What are the characteristics of metarterioles? |
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Definition
They regulate blood flow through capillary beds
Tunica intima lacks elastic lamina
Tunica media is an incomplete single layer of smooth muscle
Tunica adventitia is indistinguishable |
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Term
| How do veins differ from arteries? |
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Definition
Tunica media is much thinner in veins
Tunica adventitia is the thickest layer
Since BP is low in veins, they have valves to help ensure return of blood to the heart |
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Term
| What are the characteristics of large veins? |
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Definition
Largest veins in the body
Tunica intima is well developed and there is an internal elastic lamina. Intima protrudes into lumen and forms valves
Tunica media contains several layers of smooth muscle
Tunica adventitia is the best-developed and thickest layer. Contains a lot of smooth muscle |
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Term
| What are the characteristics of medium and small veins? |
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Definition
Tunica intima can form valves but lacks internal elastic lamina
Tunica media is relatively thin
Tunica adventitia is relatively thick but very little muscle (mostly collagen) |
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Term
| What are the characteristics of venules? |
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Definition
Smallest vein
Tunica intima is typical but does not form valves
Tunica media is very thin
Tunica adventitia is very thin and mostly collagen
Contains a discontinuous layer of smooth muscle |
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Term
| What is the blood supply to the vessels? |
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Definition
Vasa vasorum (“vessels of the vessels”)
-Vascular supply to vessel walls (esp.aorta and vena cava)
-Penetrate from periphery (deeper in veins b/c they have less oxygen) |
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Term
| What is the nerve supply to the vessels? |
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Definition
Vasomotor fibers
-Sympathetic (motor), Unmyelinated
-Smooth muscle contraction
Sensory
-Myelinated in adventitia
-Lose myelin and penetrate into media (some to initma) as “free nerve endings”
-Stretch receptors |
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Term
| What is the function of the lymphatic system? |
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Definition
Blind-ending lymphatic capillaries collect excess tissue fluid from peripheral capillary beds
- venous system cannot collect all the fluid from the tissues, lymphatic system prevents edema
- the system is unidirectional |
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Term
| What are the characteristics of the lymphatic vascular system? |
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Definition
Lymphatic vessels have thin walls (even thinner than veins), more collapsed than veins, and contain valves
Lymphatic capillaries are termed lacteal because they look like they contain milk. Lumen is very white and wide. They also have thin walls with irregular borders |
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Term
| How is the lymph that is collected returned to the blood? |
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Definition
Lymph collected from the peripheral capillary beds is
returned to the blood at the junction of the jugular and subclavian veins in the root of the neck |
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Term
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Definition
Blockage of lymph flow by lymphatic filariasis (Filaria parasitic infection)
Causes massive edema if parasite infection is untreated. Usually only occurs in 3rd world countries |
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