, 26-1 The organs of the urinary system function in excreting wastes and regulating
body fluids
• The urinary system removes most of the metabolic wastes produced by the
body’s cells.
• Organs involved; paired kidneys, ureters, bladder, urethra
• paired kidneys have excretory functions in the urinary system. These organs
produce urine,
• urine = water + ions, + small soluble compounds
• urinary tract consists of paired tubes called ureters,
• urinary bladder, a muscular sac for temporary urine storage;
• urethra - a tube
• urination, or micturition - the process of urine leaving the body
• In this process, the urinary bladder contracts and forces urine through the
urethra, which conducts the urine to the exterior.
• Function: regulate blood, conserve nuts, control Ca+ lvls, elimination,
Homeostatic regulation of the volume and solute concentration of blood
plasma
Urinary System Functions
major functions of (1)
excretion, the removal of
metabolic waste products
from body fluids, (2)
elimination of these wastes
(3)homeostatic regulation of
the volume and solute
concentration of blood.
,Regulation are the following:
• Regulating blood volume and blood pressure, by adjusting the volume of water
lost in urine, secreting erythropoietin, and releasing renin.
• Regulating plasma concentrations of Na, K+, Cl, and other ions, by influencing
the quantities in urine. The kidneys also control the calcium ion level through
the synthesis of calcitriol.
• Helping to stabilize blood pH, by controlling the concentrations of hydrogen
and bicarbonate ions in urine.
• Conserving valuable nutrients, by preventing their loss in urine while removing
metabolic wastes—especially the nitrogenous wastes urea and uric acid.
• Assisting the liver in detoxifying poisons and, during starvation, the
deamination of amino acids for their metabolic use by other tissues
• Keep the composition of blood within acceptable limits. A disruption of any one
of them has immediate consequences and can be fatal.
26-2 Kidneys are highly vascular organs containing functional units called
nephrons
• major excretory organs
• nephrons - functional units of the kidneys, tubular structures where Urine
production begins in microscopic,
• located on either side of the vertebral column, between vertebrae T12 and L3
• left kidney lies slightly superior to the right kidney. The right kidney is pushed
down bc of the liver
• superior surface of each kidney is capped by an adrenal gland.
• kidneys are held in position within the abdominal cavity by (1) the overlying
peritoneum, (2) contact with adjacent visceral organs, and (3) supporting
connective tissues.
• Three concentric layers of CT protect and stabilize each kidney, which are,
from deep to superficial
• 1. The fibrous capsule, a layer of collagen fibers that covers the outer surface
of the entire organ
, • 2. The perinephric fat, a cushioning, thick layer of adipose tissue that
surrounds the fibrous capsule
• 3. The renal fascia, a dense, fibrous outer layer that anchors the kidney to
surrounding structures. Collagen fibers extend outward from the fibrous
capsule through the perinephric fat to this layer. Posteriorly, the renal fascia
fuses with the deep fascia surrounding the muscles of the body wall. Anteriorly,
the renal fascia forms a thick layer that fuses with the peritoneum
• In effect, each kidney hangs suspended by collagen fibers from the renal
fascia and is packed in a soft cushion of adipose tissue. ** stabilize during
jolts / rapid movement
• floating kidney = If the suspensory fibers break or become detached, a slight
bump or hit can displace the kidney and stress the attached vessels and
ureter. may cause pain or distortion of the ureter or blood vessels
Gross Anatomy of the Kidneys
• kidneys are bean-shaped organs served by renal blood vessels, lymphatics,
and nerves adjacent to the proximal region of the ureters.
