Microanatomy Flashcards

Question

Tunica media of elastic arteries

Answer 1

Lamellar units made up of elastic lamina (fenestrated), smooth muscle and collagen fibres Circular orientation around vessel

Answer 2

Collagen and elastin fibres Small blood vessels (vasa vasorum) Autonomic nerves

Answer 3

Four layers: 1) endothelium 2) basement membrane of endothelium 3) subendothelial connective tissue 4) distinctive internal elastic lamina

Answer 4

Middle, thickest coat Smooth muscle fibres control diameter Elastin fibres give resiliency Collagen fibres limit expansion and prevent rupture Outer margin can include external elastic lamine - not as prominent as internal

Answer 5

Usually only collagen and elastic fibres | Vasa vasorum to service outer layers

Answer 6

Sedentary lifestyle Diet high in saturated fat Alcohol Smoking

Answer 7

Weakening of tunica media of artery Usually in the brain Risk increases with age and blood pressure

Answer 8

Tunica intima starts to thicken, internal elastic lamina breaks down Lipids increase Endothelium is activated Macrophages are recruited Macrophages accummulate into foam cells Foam cells aggregate into plaques Smooth muscle activates and invades tunica intima Atherosclerotic plaque with fatty streaks and cholesterol slits narrows lumen of vessle, causes change in flow, disrupts homeostasis Can break off and embolise, or collagen caps can form around it making it more stable

Answer 9

As plaque develops, tunica media thins out, causing it to rip Common in abdominal aorta

Answer 10

Tunica intima thickening Internal elastic lamina duplication Increase in smooth muscle layers which increases peripheral resistance Increase in density and thickness of tunica adventitia which increases collagen fibres

Answer 11

Less than 100 microns in diameter Three or fewer layers of smooth muscle in tunica media Wall thickness about equal to lumen Intima comprised of endothelial cells overlying a basal lamina Internal elastic lamina present in large arterioles Thicker muscle coat in media than any other vessel Greatest pressure drop of all vessels Variation in diameter has pronounced effect on blood flow

Answer 12

``` Arteriole Terminal arteriole Splits into metarteriole and pre-capillary sphincter Continues into thoroughfare channel Capillary bed Post-capillary venule Continues into muscular venule Lymph capillaries dotted throughout ```

Answer 13

When an arteriole leads directly to a venule without any capillaries arising from it as side branches If their muscle coats are relaxed they allow blood to shunt directly from the arterial to the venous system If their muscle coats contract then blood is forced into nearby metarterioles and then into capillary beds which they supply

Answer 14

Controls entry of blood from arteriole into capillary | When closed, blood is directed via a thoroughfare channel to a venule, bypassing the capillary bed

Answer 15

Continuous Fenestrated Sinusoids

Answer 16

Tight junctions and intercellular clefts which can be closed or open Found in blood brain barrier, muscle, connective tissues and lungs Allow passage of water, ions and small molecules but not plasma proteins

Answer 17

Either closed or open perforations Closed by thin, non-membranous diaphragms Common in intestines, endocrine glands and kidneys

Answer 18

Wide-bore capillaries with large gaps between edges of adjacent endothelial cells Gaps allow easy passage of large molecules and whole cells Found in bone marrow, spleen and liver

Answer 19

Drain capillary beds Lack smooth muscle but do have pericytes During inflammation and allergy leak blood plasma into surrounding tissue causing oedema

Answer 20

Large Up to two layers of smooth muscle in tunica media Thin wall in relation to diameter Endothelial nuclei that bulge into the lumen

Answer 21

Contractile cells that wrap around endothelial cells in capillaries and venules

Answer 22

Visible pooling of blood in the legs due to incompetent valves in superficial veins

Answer 23

Infoldings of tunica intima Prevent backflow Bicuspid

Answer 24

Blood clot forms normally in deep veins of lower leg Part of clot can break loose and embolise which is likely to pass through right heart and lodge in pulmonary arterial tree

Answer 25

``` Surgery Childbirth Trauma The pill Sitting still for a long time ```

Answer 26

When walking, valves break up column of blood into segments with each segment experiencing only tjhe gravitational pressure proportional to its height, then bolus is pushed up by skeletal muscle compression on the veins

Answer 27

Blind-ending endothelial tubes Endothelial cells tethered to surrounding connective tissue by delicate anchoring filaments No basement membrane Large intercellular clefts

Answer 28

Larger lymphatic vessels that lymphatic capillaries drain into Thin walls and lots of valves Eventually enter a lymph node Lymph enters into bloodstream via thoracic duct and right lymphatic duct

Microanatomy Flashcards

(52 cards)