Near and before the point where the afferent arteriole enters the glomerulus, its lining layer becomes enlarged and contains secretory granules. A cross section of a kidney reveals the renal sinus and two layers of kidney tissue distinguishable by their texture and colour.
All rights reserved. When these reach the boundary between the cortex and the medulla they split almost at right angles into branches called arcuate arteries that curve along between the cortex and the medulla parallel to the surface of the kidney. Situated in the middle of the medial concave border is a deep vertical cleft , the hilus, which leads to a cavity within the kidney known as the renal kidney sinus.
Philadelphia, Pa.: See also nephron. The kidneys are supplied with sympathetic and parasympathetic nerves of the autonomic nervous system , and the renal nerves contain both afferent and efferent fibres afferent fibres carry nerve impulses to the central nervous system; efferent fibres, from it. The lymphatic networks inside the capsule and around the renal blood vessels drain into lymphatic channels accompanying the interlobular and arcuate blood vessels.
Although all nephrons in the kidney have the same general disposition , there are regional differences, particularly in the length of the loops of Henle. The urinary bladder is a hollow muscular organ forming the main urinary reservoir. Parasympathetic nerves are concerned with contraction of the muscular walls of the bladder and with relaxation of its sphincter.
LiveScience - Urinary System: Articles from Britannica Encyclopedias for elementary and high school students. Thus, in the pelvis and the calyxes of the kidney the lining is two to three cells deep; in the ureter, four to five cells thick; and in the bladder, six to eight cells.
Table Of Contents. Definition By Mayo Clinic Staff.
Throughout most of the cortex the efferent arterioles redivide into a second set of capillaries, which supply blood to the proximal and distal renal tubules. The major calyxes are divided in turn into four to 12 smaller cuplike cavities, the minor calyxes , into which the renal papillae project.
It consists of inner longitudinal and outer circular layers, and fibres from the latter intermix with those in the anterior wall of the vagina, in which the urethra is embedded.