CV histo week 1

Question 1

The cardiovascular system is the transport system that carries blood and lymph to and from the tissues of the body. What are its components?

Answer 1

hear, blood vessels, and lymphatic vessels

Question 2

In the capillary beds, there is two directional exchange of fluid called ____ ____ where oxygen, CO2, metabolites, and waste are exchanged.

Answer 2

blood filtrate

Question 3

Describe the pattern of lymph drainage.

Answer 3

Fluid that escapes from the capillary bed goes into lymph capillaries and is returned to the blood by coursing into larger and larger lymphatic vessels that evetullay drain into veins of the neck.

Question 4

What vessels do WBCs leave circulation to go into tissues?

Answer 4

venules

Question 5

True or false: Each organ has a patterns or blueprint for blood flow which is characteristic for that organ. (liver, spleen, kidney, etc.)

Answer 5

True.

Question 6

What is the composition and function of the fibrous skeleton of the heart?

Answer 6

It is composed of dense irregular CT. It provides attachment sites for the leaflet of all four valves of the heart (aortic, pulmonic, tricuspid, mitral). Also provides attachment for the myocardium. Extends into the membranous portion of the interventricular septum where it lies adjacent to a portion of the conduction system. Also acts as an electrical insulator by preventing flow of electrical impulses btwn atria and ventricles.

Question 7

What is included in the impulse conduction system of the heart? What are these parts made of? What are they controlled by?

Answer 7

1. made up of the SA node, AV node, bundle of His, right and left bundle branches, Purkinje fibers
2. highly specialized cardiac muscle cells NOT NERVE CELLS!
3. regulated by the autonomic nervous system

Question 8

What are the 3 layers of the heart and what are their compositions?

Answer 8

From outside in: epidcardium, myocardium, endocardium

epicardium: outermost layer of mesothelial cells (simple squamous epithelium), small amount of CT, blood vessels (coronary arteries for example), nerves, fat
myocardium: cardiac muscle and accompanying CT, specialized fibrous skeleton in certain locations
endocardium: fibroelastic CT in a loose arrangement, impulse conduction system elements (in certain locations), innermost layer is endothelium (simple squamous epithelium) facing the lumen of each chamber and covering the valves as well, may include bundles of Purkinje fibers

Question 9

Question 10

True or false: The contraction of cardiac muscle is vigorous, rhythmic, and under the contol of both the ANS and circulating hormonse. The structrual arrangment of intercalated discs allows the heart to contract in a wringing fashion.

Answer 10

True.

Question 11

What is the flow of blood through the varying sizes of arteries and veins?

Answer 11

Blood flows from the heart into large (elastic) arteries that lead to muscular (distributing) arteries and then to arterioles. Capillary beds vary in permeability and have some specializations for exchange properties. Blood enters the venous side by passing into venules (also sites for exchange) and then into veins of increasing size.

Question 12

What are the 3 layers/tunics of vessels?

Answer 12

Tunica intima

Tunica media

Tunica adventicia

Question 13

What is located in the tunica intima, tunica media, and tunica adventicia?

Answer 13

tunica intima: endothelium linging with its basal lamina. Adjacent, a subendothelial layer consisting of loose CT. In arteries and arterioles, there is also an internal elastic lamina which is a sheetlike lamina of fenestrated elastic membrane.

tunica media: Contains circumferentially arranged smooth muscle cells. Also contains collagen, elastin, reticular fibers (type III collagen) and proteoglycans interwoven with the smooth muscle. Arteries have organized layers of elastic fibers in the tunica media. The fenestrations in these sheets of elastic allow for passage of molecules and can house bundles of smooth muscle interwoven within this layer. The boundaries of the tunica media in an artery extend from the internal elastic membrane to the exernal elastic membrane. This layer is larger in arteries than in veins.

tunica adventicia: longitudinally arranged collagenous tissue with elastic fibers. These CT elements wil erge with the CT surrounding the vessel. In large vessels, this layer contains the vasa vasorum (vessels contained within the wall of a vessel) and nervi vascularis (nerve fibers in the wall of a vessel). In veins, this layer is thicker than the companion artery and in large veins, smooth muscle may be present in this layer.

Question 14

What are the types of vessels?

Answer 14

Question 15

What are some features of large elastic arteries? Name one example in the body.

Answer 15

Aorta is a large elastic artery.

features:

• relativley thick tunica intima
• thick tunica media with prominent elastic laminae
• tunica adventitia with vasa vasorum and nervi vascularis

please see pg 85 of course notes for another pic

Question 16

What are some features of muscular arteries? Where are they found in the body?

Answer 16

Most arteries are muscular arteries.

features:

• thinner tunica intima (than elastic arteries)
• prominent internal elastic lamina
• thick tunica media
• external elastic lamina (sometimes visible)

Question 17

What are some features of arterioles?

Answer 17

Arterioles regulate flow to capillary beds.

• have only 1-2 layers of smooth muscle in the tunica media
• very thin tunica intima
• no internal elastic lamina
• thin tunica adventicia

see pg 87 of course notes for another pic

Question 18

What are features of capillaries?

Answer 18

• lumen is typcially 8-12 micrometers in diameter and permits only a single RVC to maneuver through the lumen at a time
• vessel wall is a simple tube comprised of endothelium and basal lamina (tunica intima)
• may have a tunica media comprised of a pericyte

Question 19

What is a pericyte?

Answer 19

• CT cell that is similar to mesenchymal cells
• surrouds capillary endothelium within the basal lamina providing physical stability
• has contractile ability
• participates in physical and chemical signaling within the endothelium
• may give rise to endothelial cells and smooth muscle cels during wound healing (angiogenesis)

Question 20

What are the 3 types of capillaries and where in the body are they typically found?

Answer 20

1. continuous capillary: fat, muscle, lung, nervous system (CNS)
2. fenestrated capillary: intestinal vili, endocrine glands, kidney glomeruli
3. discontinuous/sinusoidal: liver, bone marrow, spleen

Question 21

What are the features of continuous capillaries?

Answer 21

• numerous pinocytic vesicles
• tight junctions
• located in muscle, lung, CNS, fat

Question 22

What are features of fenestrated capillaries?

Answer 22

• less pinocytic veislces than continuous (bc have fenstrations)
• may have diaphragms across fenestrations
• locations include endocrine glands, GI tract, kidney glomeruli

Question 23

What are features of sinusoidal capillaries?

Answer 23

• large diameter lumen
• spaces btwn endothelial cells
• incomplete basal lamina
• locations include spleen, liver, bone marrow

Question 24

How is the flow through microvessels controlled? What is the effect of vasodilating agents on aterioles and what effect does this have on capillaries?

Answer 24

Flow through the microvessel network is under local and systemic control. Arterioles respond to vasodilating agents (NO, O2) by relaxation of smooth muscle and results in increased flow. This increased pressure within the capillary drives plasma into the surrounding tissue resulting in edema.

Question 25

How is blood flow to capillaries locally controlled as it pertains to AV shunts and metarterioles? Why may AV shunts be used?

Answer 25

Arteriovenous anastamosis (shunt) is a communication btwn an artery and a vein. Allows blood to bypass capillary circulation. Serves as function of phasic activity of an organ. When active, AV shunts are close and blood circulates through capillaries and are open when organ is inactive in order to bypass the capillary bed. Also used for temperature regulation in shunting heat away from skin to conserve for organs. Metarterioles are preferential thoroughfares (way or place for passage, main road) in capillary beds. Smooth muscle sphincters called capillary sphincters are located on the origin of capillaires coming off of metarterioles. Blood flow to capillaries is controlled by these sphincters.

Question 26

What are features of veins?

Answer 26

Have walls with tunics but layers are not as distinct or as well defined as arteries. When compared to accompanying arteries, veins have the following features: * veins have a larger lumen * have thinner walls (much less t. media) * often are irregular or collasped

Question 27

Capillaries---\>post-capillary venules---\>venules---\>small/medium veins---\> large veins---\> heart

Question 28

What is the fxn and composition of post-capillary venules? What chemicals act here and what are their effects? What process occurs here? What are the features?

Answer 28

* receive blood from capillaires * endothelium is the site of action for histamine and serotonin which results in: * 1. exit of fluids into tissue from these vessels * 2. extravasation of WBCs into tissue from these vessels * in lymph nodes, post-capillary venles are the sites of migration of lymphocytes * lumen is 10-15 micrometers in diameter * wall is a simple endothelial tube-T. initma * may have a T. media comprised of a pericyte (no smooth muscle)

Question 29

What are the features of venules?

Answer 29

* lumen up to 100 micrometers in diameter * very thin wall-t. intima * no smooth muscle (no T. media) * look like dilated capillaries, T. adventicia blends in

Question 30

What are features of small to medium veins? (note that most veins are of this type)

Answer 30

* lumen diameter up to 10 mm * T. media has smooth muscle, elastic and collagen fibers * T. adventicia is thicker than the media and has network of collagen and elastic fibers. blends in with surrounding CT.

Question 31

What are features of large veins? What are some examples?

Answer 31

Examples include subclavian veins, portal vein, vena cava * T. intima as endothelium and subendothelial CT with internal elastic lamina * T. media has _circumfirential_ smooth muscle, collage, fibroblasts. thin relative to lumen size * T. adventicia is the thickest tunic-has collagen, elastic fibers, fibroblasts and bundles of _longitudinally oriented smooth muscle fibers_ please see pg 97 of notes for another pic

Question 32

Lymphatic vessels convey a fluid called lymph throughout the body. Lymphatic circulation is a unidirectional system-from the tissues back to the blood vascular system and typically have valves to aid in the direction of flow. The walls resemble veins and lack a distinct separation twn the 3 tunics. Endothelium lines this system throughout. Most lymphatic vessels are associated with lymph nodes. What types of vessels does it consist of? What are the largest lymphatic vessels?

Answer 32

1. lymphatic capillaries, including lacteals 2. lymphatic vessels-small to large largest lymphatic vessels are the right lymphatic trunk and the thoracic duct

Question 33

What are features of lymphatic capillaries? Where are they found and what is their fxn?

Answer 33

Lymphatic capillaries are most numerous in loose CT under the epithelium of skin and mucous membranes. (respiratory, GI tract). Permeable and are effective (given these locations) in conveying protein rich fluid. Are also interspersed in capillary beds. features: - blind ended - simple endothelial tubes - have anchoring filaments (contain elastic fibers) - have discontinuous basal lamina

Question 34

Where are lacteals found and what is their fxn?

Answer 34

In the villi of the small intestine, lacteals convey proteins and lipids that are too large to cross fenestrations of the blood capillaries.

Question 35

What are the features of small to medium lymphatic vessels?

Answer 35

* simple endothelial tubes * have anchoring filaments (contain elastic fibers) * may have valves

Question 36

What are features of the thoracic duct? Where does it empty its contents? How does it compare to veins?

Answer 36

Empties contents into venous circulation at the base of the neck. Compared to veins of similar diameter, the thoracic duct (which is 4-6 mm) have thinner walls overall and indistinct separation btwn tunics. T. media has both circular and longitudinal bundles of smooth muscle and T. adventicia has scattered smooth muscle.

Question 37

What are the characteristics of endothelial cells in vessels? What specialized organelle do they contain and what is its purpose? What disease can result if there are issues with this organelle?

Answer 37

* are elongated parallel to the direction of blood flow * have junctions to adjacent cells (zonula occludens/tight junctions, zonula adherens/adhering junctions, macula adherens/desmosomes) * anchored to basal lamina via hemidesmosomes * contained the specialized oorganelle: Weibel-Palade body. Weibel-Palade bodies contain von Willebrand factor which plays and important role in blood coagulation. Deficiency results in von Willebrand Disease. please see pg 101 of course notes for pic

Question 38

What are the properties and fxns of the endothelium? What is endothelial activation?

Answer 38

Endothelial activation is the term collectively used to describe the multiple processes and fxns of the endothelium. These cells can: * respond to stimuli (bacterial and viral antigens, lipid products, hypoxia, cytotoxins) * maintain selective permeability barrier * maintain non-thrombogenic barriers btwn platelets and subendothelial tissue * modulate blood flow and vascular resistance * regulation of cell growth (secretes growth factors) * modulate immune responses * maintains ECM (basal lamina, glycocalyx) * inactivates/converts compounds in the blood (Angiotensin I to Angiotensin II) * modification of lipoproteins Endothelial activation is also responsible for the pathogenesis of any vascular diseases.

Question 39

aneurysm

Answer 39

a weakening in the vessel wall that is usually related to the T. media layer and a specific defect in collagen

Question 40

ischemic heart disease

Answer 40

usually caused by coronary artery obstruction with diminished blood flow to the myocardium. may result in angina pain and possible MI

Question 41

varicose veins

Answer 41

backflow of blood from deep veins into superficial veins due to fault valves. results in dilated veins-alteraltion in the vessel wall and valvular incompetence in veins

Question 42

Transplanted heart: dennervated organ-no ANS innervation to modulate and coordinate the organ with the environment. Immune response-cellular rxn?

Question 43

What is atherosclerosis? What are the processes that lead to it? What diseases may result?

Answer 43

Atherosclerosis is a very common lesion of blood vessels wherein deposits of plaques (atheromas) are present in the intima of large and medium sized arteries. Blockage or obstruction of flow is likely a related problem. Lesions develop in the T. intima and consist of a thick layer of fibrous CT containing macrophages, foam cells, lymphocytes, and cell debris. Depending upon location of vessel, can lead to variety of pathologic conditions including MI, CVA, gangrene of limbs. How it happens: High levels of lipid inteh blood produce a cascade of events. Endothelial cells initiate monocyte migration. Platelet-derived growth factor (PDGF) and other growth factors stimulate migration of smooth muscle cells into the T. intima. Macrophages and smooth muscle cells accumulate LDLs forming foam cells. Thickening of T. intima with roughened surface of vessel lumen can be called a plaque.