Chap. X] 



LYMPH VASCULAR SYSTEM 



181 



Valves 



Semilunar 

 valves 



Nerve Supply 



Blood Supply 



Coats , 



2. Muscular and elastic tissue 



Tricuspid valve — composed of three cusps situated 



in the right ventricle. 

 Bicuspid or mitral valve — composed of two strong, 

 thick cusps situated in the left ventricle. 

 f Aortic — composed of three half-moon- 

 I shaped pockets between 



aorta and left ventricle. 

 Pulmonary — composed of three half- 

 moon-shaped pockets be- 

 tween pulmonarj^ artery 

 and right ventricle. 

 Central nervous system — Pneumogastric nerves, 



inhibitory fibres, slow the heart. 

 Sympathetic system — Accelerator fibres increase 

 rapidity and force of heart. 



Right coronary artery ] , , . 



J f, X } branches from aorta. 



Lett coronary artery j 



Hollow tubes — Carry blood from heart. 

 1. Endothelial lining. 



contractile and 

 elastic. 

 , 3. Fibrous tissue. 

 Sheaths — outside covering of connective tissue which sur- 

 rounds the arteries. 

 Size — Aorta about one inch in diameter. Arteries grow 

 smaller as they subdivide. Smallest ones are 

 microscopic and are called arterioles. 

 Tmy tubes — about Woo of an inch in diameter. Connect 



arterioles and venules. 

 One coat of simple endothelium. 

 . Communicate freely — form networks. 

 Collapsible tubes — smallest ones, called venules, begin where 



capillaries end. 

 Carry blood to heart. 

 Three coats, same as arteries but thinner. 

 Less elastic and contractile. 

 , Valves. 1-2-3 semilunar pockets. 



Vaso vasorum — Term appUed to blood-vessels that are supplied to coats 



of other blood-vessels. 

 Vasomotor — Term applied to nerves supphed to ( Vaso-constrictor. 

 blood-vessels — 2 sets I Vaso-dilator. 



Arteries 



Capillaries 



Vfeins 



