This article is for undergraduate nurses who wish to obtain a greater understanding of applied anatomy and physiology. There are four questions to be attempted during the reading session. The answers are given at the end of the session.
The Human Renal System
The human renal system is made up of two kidneys, two ureters, the urinary bladder, and the urethra. In addition to the production of urine the renal system has many other functions.
One quarter to one fifth of cardiac output passes through the kidneys at all times. This means that the kidneys filter approximately 1.2 liters of blood every minute. It is therefore not surprising that even slight abnormalities of renal function quickly lead to electrolyte disturbances. If untreated death will occur.
The kidneys are two bean shaped organs of the renal system located on the posterior wall of the abdomen one on each side of the vertebral column at the level of the twelfth rib. The left kidney is slightly higher than the right. Why do you think that the right kidney is lower than the left? (Q1). Human kidneys are richly supplied with blood vessels which give them their reddish brown color. The kidneys measure about 10cm in length and, 5cm in breadth and about 2.5 cm in thickness.
The kidneys are protected by three highly specialized layers of protective tissues. The outer layer consists mainly of connective tissue which protects the kidneys from trauma and infection. This layer is often called the renal fascia or fibrous membrane. The technical name for this layer is the renal capsule. The next layer (second layer from the exterior) is called the fascia and it makes a fibrous capsule around the kidneys. This layer connects the kidneys to the abdominal wall. The inner most layer is made up of adipose tissue and is essentially a layer of fatty tissue which forms a protective cushions the kidney; and the renal capsule (fibrous sac) surrounds the kidney and protects it from trauma and infection.
Blood and Nerve Supply:
The kidneys receive their oxygenated blood supply from the renal arteries which come off the abdominal portion of the aorta. Venous blood from the kidneys drains into the renal veins to join the abdominal portion of the inferior vena cava.
The hilum of the kidneys is located toward the smaller curvature. The opening in the hilum allows for the entry and exit of blood vessels and nerves. The funnel shaped extension of the kidneys is called the renal pelvis and it connects the kidneys to the two ureters. This structure facilitates the collection of the urine from the kidneys and drainage to the urinary bladder.
The ureters are tubes that are 25-30cm long and lined with smooth muscle. These tubes help carry urine to the bladder. The muscular tissue helps force urine downwards. They enter the bladder at an angle, so urine doesn’t flow up the wrong way.