cardiovascular

Question 1

Heart

Answer 1

endocardium(tunica intima) ;single layer of squamous endothelial cells resting on a thin subendothelial layer of loose connective tissue that contains elastic and collagen fibres. Myocardium (tunica media)-thickest and has cardiac muscle cells ,intercalated discs join cardiac muscle fibres Epicardium(tunica adventitia)-simple squamous epithelium(mesothelium)

Question 2

fibrous skeleton of the heart

Answer 2

consists of:septum membranaceum,trigona fibrosa and annuli fibrosa

Question 3

cardiac valves

Answer 3

consist of a central core od dense fibrous connective tissue . bases of the valves are attached to annuli fibrosi

Question 4

conducting fibres

Answer 4

sino artrial node,AV node,bundle of HIS ,bundle branches and purkinje fibres.

Question 5

conducting fibres have

Answer 5

few myofibrils,abundant glycogen granules &mitochondria,connect to each other through desmosomes and gap junctions.Do not have intercalated discs.

Question 6

pericytes

Answer 6

have a contractile function in the cappilaries.They also diffentiate to form new blood vessels and connective tissue cells incase of injury to capillaries

Question 7

functions of endothelial cells

Answer 7

1.act as a permeability barrier 2.synthesize collagen and proteoglycans for basement membrane maintenance. 3.synthesize and secrete molecules which promote protective thrombus formation. 4.synthesize and secrete molecules which minimize pathological thrombus formation;pristacyclin,NO,Thrombomodulin 5.secrete vasoactive factors controlling blood flow:NO,Prostacyclin and endothelin. 6.produce molecules which mediate the acute inflammatort reaction;IL 1,6 &8 7.produce some growth factors;Fibroblast growth factor

Question 8

lymphatic vessels are found in all tissues except

Answer 8

CNS,Cartilage,bone,bone marrow,thymus,placenta,cornea &teeth.

Question 9

difference btwn lymphatic cappilaries and blood capillaries

Answer 9

endothelium cell cytoplasm of lymphatic is extremely thin basement membrabe is absent no pericytes fine cartilagenous filaments known as anchoring filaments link the endothelium to the sorrounding supporting tissue preventing collapse of lynphatic lumen