e. The kidneys are very vascular because one-fourth of the entire volume of
blood passes through them at any one time. They receive their blood supply through
the renal arteries that originate from the aorta. Each renal artery divides into several
branches called afferent vessels.
f. The lymphatic supply for the most part drains into the lymph nodes that are
located between the renal vessels and the aorta, and it accompanies the venous
g. The nerves of the autonomic (involuntary nervous) system carry pain
sensations from the urinary organs. The nerve supply to the kidney comes from the
lumbar sympathetic trunk and from the vagus nerves. Removal of the nervous
pathways disrupts the ability to feel pain without impairing kidney function.
Each ureter is a continuation of the cuplike calyces and renal pelvis. The ureter
extends from the renal pelvis to the base of the bladder as a cylindrical tube. Each tube
is about 25 to 30 cm long (10 to 12 inches) and 4 to 5 mm (1/5 inch) in diameter. Each
consists of three layers: an outer adventitial layer, a muscular layer, and an inner
epithelial lining. See figure 3-5.
Figure 3-5. Genitourinary system (male).