Exam II: Cardiovascular System (Capillaries to Lymphatic Ducts) Flashcards
Blood flow into capillaries is controlled/influenced by:
- Metarterioles
- AVA’s (AV shunt- some locations only)
- Lumen size of terminal arteriole
- Pre-capillary sphincters
Form tiny pockets though the cytoplasm of capillaries
Pinocytotic Vesicles
Function of Pinocytotic vesicles
Movement of large molecules
Cell junction located in capillaries
Fasclae occludens (between endothelial cells)
Functions of cell junctions in capillaries
- Move macromolecules
- Allows cell movement
Most common capillary type and locations present
Continuous capillaries
-muscle, connective tissue, many organs
Cell often considered to be residual mesenchyme cells. They are numerous on capillaries and venules, can secrete basement membrane and matrix components.
Pericytes
Pericytes ___ divide and can change into:
Can divide
Change into: 1) Endothelial cells 2) Smooth muscle cells 3) Fibroblasts (all 3 cells are important for tissue repair and maintenance )
T/F Pericytes have contractile filaments
True
Functions of pericytes
- Important for healing
- May regulate blood flow (hypothesis only)
Modified continuous capillary in the CNS
- Zonula occludens instead of fasciae occludens
- Barrier regulation by endothelium, but influenced by astrocytes
Name and location of capillaries that have pores with a thin protein diaphragm containing 8 fibrils
Fenestrated capillaries
-Pancreas, intestines, endocrine organs, kidneys
Function of Fenestrated capillaries
To allow greater movement of molecules and cells
Name and location of capillaries with an enlarged diameter and many large fenestrae with no protein diaphragm
Sinusoidal capillaries (sinusoids)
Function of sinusoidal capillaries
Enhanced exchange between blood and tissues
T/F Arteries and veins both have 3 tunics
True
How are veins different from arteries?
Veins are:
- Not as uniform in structure
- Often larger
- Have higher numbers
What makes up the valves of veins?
Valve consists of 2 flaps of tunica intima and fibroelastic connective tissue
Functions of valves in veins
- Protection by preventing backflow
- Works with skeletal muscle to keep blood moving
Venule with a tunica intima that has endothelium, small amount of connective tissue, and numerous pericytes. No tunica media or tunica adventitia present.
Postcapillary venules
Venule with a tunica intima that have an endothelium and small amount of connective tissue. Also have a tunica adventitia composed of connective tissue, fibroblasts, and some pericytes. No tunica media is present.
Collecting venules
Venules with a present tunica intima, a tunica media consisting of an incomplete smooth muscle layer, and a tunica adventitia present with a few pericytes (fewest of all types)
Muscular venules
An incomplete tunica media allows products of inflammation(ex: histamine and leukotrienes) to loosen endothelial cell junctions causing:
Leaky venules
Structure is similar to venules except these have a complete tunica media (still thin though)
Small veins
Type of vein with a tunica intima that has endothelium, basal lamina, connective tissue with reticular fibers, sometimes elastic fiber network (but no IEL), a tunica media that has smooth muscle, collagen, and fibroblasts, and a tunica adventitia with connective tissue, collagen, elastic fibers, and a few smooth muscle cells. Vasa vasorum is possible.
Medium veins
Veins where the tunica intima has thicker connective tissue with fibroblasts and a elastic fiber network, the tunica media is complete, but thin, and the tunica adventitia has much fibroelastic connective tissue and vasa vasorum
Large veins
What is the thickest layer of large veins?
Tunica adventitia
What is the exception to typical structure of veins for the superficial veins of legs?
Tunica media well developed (must fight gravity)
What are the exceptions to typical structures of veins for the pulmonary veins?
- Tunica media is well developed
- Tunica adventitia has some cardiac muscle close to the heart
What are the exceptions to typical structures of veins for the vena cava?
Tunica adventitia has some cardiac muscle close to the heart
What are the exceptions to typical structures of veins for the inferior vena cava?
Tunica adventitia may possibly have some cardiac muscle close to the heart
Enlarged and winding superficial veins in the leg. Possibly caused be loss of skeletal muscle tone around the veins, degeneration of the vessel wall, or valve incompetence
Varicose veins
Varicose veins in lower esophagus. Common in alcoholics and is caused by portal hypertension
Esophageal varices
Varicose veins at the end of the anal canal
Hemorrhoids
Functions of lymphatic vessels
- Drain excess interstitial fluid
- Transport lymph to lymph nodes (for foreign antigen detection in nodes)
- Transport lymph to blood stream
Differences of lymphatic capillaries from blood capillaries
- Blind ended (suddenly begin)
- No pericytes
- Endothelial cells can overlap, but create clefts between cells that allow for easy movement of materials into and out of vessels
- No fenestrae and no tight junctions between endothelial cells
- Contain bundles of lymphatic anchoring filaments
What is the function of the lymphatic anchoring filaments in lymphatic capillaries?
Support endothelial walls so capillaries stay open
What does the structure of small lymphatic vessels resemble?
Venules
T/F Tunics of medium and large veins blend together more than medium and large lymphatic vessels
FALSE.
Medium and large lymphatic vessel tunics blend together more than medium and large veins
What lympathic vessels has a tunica intima with endothelium and a thin layer of connective tissue with elastic fibers, a tunica media with thin smooth muscle layer, a tunica adventitia with connective tissue with collagen and elastic fibers, and present and closely spaced valves?
Medium and Large Lymphatic Venules
Lymphatic vessel that empties into the venous system at specific junctions
Lymphatic ducts
Where does the Lymphatic duct empty into the venous system?
At the junction of the right internal jugular vein and subclavian veins
What are the 2 lymphatic ducts?
Right Lymphatic Duct (shorter)
Thoracic Duct
What lympathic vessel has a tunica intima has endothelium, several layers of collagen and elastic fibers, a layer of condensed elastic fibers (similar to internal elastic lamina), tunica media has longitduinal and circular layers of smooth muscle, and tunica adventitia has longitduinal smooth muscle cells, collagenous connective tissue, and vasa vasorum- like vessels?
Lymphatic duct
