112 VETBRINAEY STATE BOARD 



forced into the aorta and, therefore, the blood-pressure is highest. 

 At the beginning of an inspiration, which is really the end of an 

 expiration, there is a negative intrathoracic pressure, the blood is 

 aspirated into the right aurjcle and the blood-pressure is lowest. 



Describe the circulation of the blood in the brain. 



Supplied by the cerebrospinal branch of the external carotid, 

 which divides into two branches, the median spinal and basilar, and 

 the internal carotid, which divides into the posterior communicating 

 and the common trunk of the anterior and middle cerebral arteries. 



The venous arrangement is very remarkable; the walls of the 

 veins are composed of the dura mater and portions of the cranial 

 bones. The veins, or sinuses of the brain, are large cavities which, 

 because of their unyielding walls, allow the venous blood to return 

 freely. The cerebral circulation is assisted by the fluid in the ven- 

 tricles of the brain. This fluid passes from one ventricle to another 

 and to the spinal cord; therefore, when the external pressure be- 

 comes greater, the internal becomes less, thereby avoiding any 

 compression of the brain substance. 



Describe the portal circulation. 



The portal circulation begins in the small mesenteric, the great 

 mesenteric and splenic veins, all of which unite to form the portal 

 vein. The latter, beginning near the great mesenteric artery, passes 

 through the pancreatic ring and divides in the great posterior fissure 

 of the liver to enter its structure, carrying the venous blood, which, 

 after circulating through the liver, leaves it by the hepatic vein. 



Describe the circulation of the blood in the kidney. 



The blood enters at the hilus by the renal artery, which breaks 

 up, after entering the organ, into a large number of branches ; these 

 branches run in a nearly parallel direction through the medullary 

 portion until the cortex is reached, where they diverge in various 

 directions to enter the Malpighian corpuscles. In these bodies 

 there is a plexus of capillaries, the glomeruli, and leading from 

 them are small vessels, arranged similar to the arterial branches, 

 which unite to form the renal vein. 



Give the normal pulse of (a) the horse, (b) the ox, (c) the dog, (d) the 

 sheep, (e) the cat. 

 (a) 36-40; (b) 45-50; (c) 90-120; (d) 70-80; (e) 90-120. 



Vasculab Glands 

 Mention the vascular glands. 



Spleen, thymus, thyroid, adrenals, pituitary and pineal bodies. 



