1 90 ANATOMY AND PHYSIOLOGY FOR NURSES 



are dilated, there is a full and rapid stream of blood through 

 the glomeruli, and an increased flow of urine results. 

 On the other hand, when the body is exposed to warmth, 

 the cutaneous vessels are widely dilated and free per- 

 spiration occurs, while the renal vessels being constricted, 

 only a small and slow stream of blood trickles through the 

 glomeruli, and the urine that is secreted is scanty in 

 amount. 



The effect of secretion, however, is governed largely 

 by the amount of fluid absorbed through the alimentary 

 canal; an increased secretion of water always follows an 

 ordinary meal, and when large quantities of water are 

 drunk, the amount of urine is correspondingly increased. 



THE SUPRARENAL CAPSULES 



The suprarenal capsules are two small, flattened bodies, 

 of a yellowish color, one situated immediately above each 

 kidney. Having no excretory duct, they are usually 

 classified with the ductless glands. Each organ is invested 

 by a fibrous capsule that sends septa into the glandular 

 substance; these septa form a framework for the soft, 

 pulpy substance of the gland, and within the spaces of this 

 framework are groups of cells. 



The suprarenal capsules are abundantly supplied with 

 blood-vessels, nerves, and lymphatics, and contain re- 

 markable coloring matters. When these organs become 

 diseased, the skin frequently becomes ' 'bronzed," from an 

 increase of pigment or coloring-matter. Their special 

 function is as yet unknown. 



THE SKIN 



Having described the mechanism by which the lungs 

 eliminate carbon dioxid and water from the body, and the 



