Chapter 26 The urinary System Flashcards
The urinary system contributes to homeostasis by
excreting wastes; altering blood composition, pH, volume, and pressure; maintaining blood osmolarity; and producing hormones. /.
As body cells carry out metabolic activities,
they consume oxygen and nutrients and produce waste products such as carbon dioxide, urea, and uric acid.
Wastes must be eliminated from the body because
they can be toxic to cells if they accumulate.
While the respiratory system rids the body of carbon dioxide, the urinary system
disposes of most other wastes.
The urinary system performs waste disposal by
removing wastes from the blood and excreting them into urine
The urinary system also
helps regulate blood composition, pH, volume, and pressure; maintains blood osmolarity; and produces hormones.
The urinary system consists of
two kidneys, two ureters, one urinary bladder, and one urethra
The kidneys
filter blood of wastes and excrete them into a fluid called urine
Once formed, urine
passes through the ureters and is stored in the urinary bladder until it is excreted from the body through the urethra.
Nephrology (nef-ROL-ō-jē; nephr- = kidney; -ology = study of) is
the scientific study of the anatomy, physiology, and pathology of the kidneys.
urology
The branch of medicine that deals with the male and female urinary systems and the male reproductive system
Urine formed by the kidneys
passes first into the ureters, then to the urinary bladder for storage, and finally through the urethra for elimination from the body
What is the function of the Kidneys
regulate blood volume and composition; help regulate blood pressure, pH, and glucose levels; produce two hormones (calcitriol and erythropoietin); and excrete wastes in urine.
What is the function of the ureters
transport urine from kidneys to urinary bladder.
What is the function of the urinary bladder
stores urine and expels it into urethra.
What is the function of the urethra
discharges urine from body.
What are ALL of the functions of the kidneys
Excretion of wastes
Regulation of blood ionic composition
Regulation of blood pH
Regulation of blood volume
Regulation of blood pressure
maintainance of blood osmolarity
Production of hormones
Regulation of blood glucose level
Some wastes excreted in urine result from metabolic reactions. These include
urea and ammonia from the deamination of amino acids; creatinine from the breakdown of creatine phosphate; uric acid from the catabolism of nucleic acids; and urobilin from the breakdown of hemoglobin.
Urea, ammonia, creatinine, uric acid, and urobilin are collectively known as
nitrogenous wastes because they are waste products that contain nitrogen.
non-nitrogenous wastes excreted in the urine are
foreign substances that have entered the body, such as drugs and environmental toxins
The kidneys help regulate the blood levels of several ions, most importantly
sodium ions (Na+), potassium ions (K+), calcium ions (Ca2+), chloride ions (Cl−), and phosphate ions (HPO42−).
The kidneys regulate blood ionic composition by
adjusting the amounts of these ions that are excreted into the urine.
The kidneys excrete
a variable amount of hydrogen ions (H+) into the urine
The kidneys
conserve bicarbonate ions (HCO3−), which are an important buffer of H+ in the blood
The kidneys excrete a variable amount of hydrogen ions (H+) into the urine and conserve bicarbonate ions (HCO3−), which are an important buffer of H+ in the blood. Both of these activities help
regulate blood pH.
The kidneys adjust blood volume by
conserving or eliminating water in the urine.
An increase in blood volume
increases blood pressure;
a decrease in blood volume
decreases blood pressure.
The kidneys also help regulate blood pressure by
secreting the enzyme renin, which activates the renin–angiotensin–aldosterone pathway
Increased renin causes
an increase in blood pressure.
By separately regulating loss of water and loss of solutes in the urine, the kidneys
maintain a relatively constant blood osmolarity close to 300 milliosmoles per liter
The kidneys produce two hormones. _________________ and ______________
Calcitriol, the active form of vitamin D, helps regulate calcium homeostasis and erythropoietin which stimulates the production of red blood cells
Like the liver, the kidneys can use the amino acid glutamine in
gluconeogenesis, the synthesis of new glucose molecules
After the kidneys create glucose molecules
They can then release glucose into the blood to help maintain a normal blood glucose level.
urine contains more than just waste products. It also contains
water and other substances, such as ions, that have important roles in the body, but are in excess of the body’s needs.
The paired kidneys are
reddish, kidney bean–shaped organs located just above the waist between the peritoneum and the posterior wall of the abdomen.
Since their position is posterior to the peritoneum of the abdominal cavity, the Kidneys
are said to be retroperitoneal
The kidneys are located
between the levels of the last thoracic and third lumbar vertebrae, a position where they are partially protected by ribs 11 and 12.
If ribs 11 or 12 are fractured
they can puncture the kidneys and cause significant, even life-threatening damage.
The right kidney is slightly lower than the left because
the liver occupies considerable space on the right side superior to the kidney
The concave medial border of each kidney
faces the vertebral column
Near the center of the concave border is an indentation called the
hilum of the kidney (HĪ-lum), through which the ureter emerges from the kidney along with blood vessels, lymphatic vessels, and nerves
What are the three layers of tissue that surround each kidney
Fibrous capsule (deep)
perirenal fat capsule (intermediate)
renal fascia (superficial)
The deep layer, the fibrous capsule, is
a smooth, transparent sheet of collagen-rich connective tissue that is continuous with the outer coat of the ureter.
The fibrous capsule
serves as a barrier against trauma and helps maintain the shape of the kidney.
The middle layer, the perirenal fat capsule (per-i-RĒ-nal), is
a mass of fatty tissue surrounding the fibrous capsule. It also protects the kidney from trauma and holds it firmly in place within the abdominal cavity.
The superficial layer, the renal fascia (FASH-ē-a), is
a collagenous and elastic dense irregular connective tissue that anchors the kidney to the surrounding structures and to the abdominal wall.
On the anterior surface of the kidneys, the renal fascia is
deep to the peritoneum.
A coronal section through the kidney reveals two distinct regions:
a superficial, light red region called the renal cortex (cortex = rind or bark) and a deep, darker reddish-brown inner region called the renal medulla (medulla = inner portion)
The renal medulla consists of
several cone-shaped renal pyramids.
The base (wider end) of each pyramid
faces the renal cortex
the apex of a renal pyramid (narrow end),
points toward the renal hilum of the kidney and is called a renal papilla,
The renal cortex is
the smooth-textured area extending from the fibrous capsule to the bases of the renal pyramids and into the spaces between them.
The renal cortex is divided into
an outer cortical zone and an inner juxtamedullary zone
Those portions of the renal cortex that extend between renal pyramids are called
renal columns.
the kidneys are surrounded by
a fibrous capsule, perirenal fat capsule, and renal fascia.
Together, the renal cortex and renal pyramids of the renal medulla constitute the
parenchyma (pa-RENG-kī-ma) or functional portion of the kidney.
Within the parenchyma are
the functional units of the kidney—about 1 million microscopic structures in each kidney called nephrons.
Filtrate (filtered fluid) formed by the nephrons
drains into large papillary ducts (PAP-i-lar′-ē), which extend through the renal papillae of the pyramids.
The papillary ducts drain into
cuplike structures called minor and major calyces (KĀ-li-sēz = cups; singular is calyx, pronounced KĀ-liks).
Each kidney has
8 to 18 minor calyces and 2 or 3 major calyces
A minor calyx
receives filtrate from the papillary ducts of one renal papilla and delivers it to a major calyx.
Once the filtrate enters the calyces
it becomes urine because no further reabsorption can occur. The reason for this is that the simple epithelium of the nephron and ducts becomes urothelium in the calyces. The urothelium blocks exchanges across the walls of these tubes.
From the major calyces, urine drains into
a single large cavity called the renal pelvis (pelv- = basin) and then out through the ureter to the urinary bladder.
The two main regions of the kidney are
the superficial, light red region called the renal cortex and the deep, dark red region called the renal medulla.
The hilum of the kidney
expands into a cavity within the kidney called the renal sinus, which contains part of the renal pelvis, the calyces, and branches of the renal blood vessels and nerves
Adipose tissue
helps stabilize the position of these structures in the renal sinus.
since the kidneys remove wastes from the blood and regulate its volume and ionic composition, it is not surprising that
they are abundantly supplied with blood vessels
Although the kidneys constitute less than 0.5% of total body mass,
they receive 20–25% of the resting cardiac output via the right and left renal arteries
In adults, renal blood flow, the blood flow through both kidneys,
is about 1200 mL per minute.
Within the kidney, the renal artery
divides into several segmental arteries (seg-MEN-tal), which supply different segments (areas) of the kidney
Each segmental artery
gives off several branches that enter the parenchyma and pass through the renal columns between the renal lobes as the interlobar arteries
A kidney lobe consists of
a renal pyramid, some of the renal column on either side of the renal pyramid, and the renal cortex at the base of the renal pyramid
At the bases of the renal pyramids,
the interlobar arteries arch between the renal medulla and cortex; here they are known as the arcuate arteries
Divisions of the arcuate arteries produce
a series of cortical radiate (interlobular) arteries (KOR-ti-kal RĀ-dē-at).
cortical radiate arteries
radiate outward and enter the renal cortex. Here, they give off branches called afferent glomerular arterioles
The renal arteries
deliver 20–25% of the resting cardiac output to the kidneys.
Each nephron receives one
afferent glomerular arteriole, which divides into a tangled, ball-shaped capillary network called the glomerulus
Each nephron receives one afferent glomerular arteriole, which divides into a tangled, ball-shaped capillary network called the glomerulus (glō-MER-ū-lus = little ball; plural is glomeruli). The glomerular capillaries then
reunite to form an efferent glomerular arteriole (EF-er-ent; ef- = out) that carries blood out of the glomerulus.
Glomerular capillaries are unique among capillaries in the body because
they are positioned between two arterioles, rather than between an arteriole and a venule.
Glomerular capillaries are unique among capillaries in the body because they are positioned between two arterioles, rather than between an arteriole and a venule. Since they are capillary networks and they also play an important role in urine formation,
the glomeruli are considered part of both the cardiovascular and the urinary systems.
The efferent glomerular arterioles divide to form
the peritubular capillaries (per-i-TOOB-ū-lar; peri- = around), which surround tubular parts of the nephron in the renal cortex
Extending from some efferent glomerular arterioles are
long, loop-shaped capillaries called vasa recta (VĀ-sa REK-ta; vasa = vessels; recta = straight) that supply tubular portions of the nephron in the renal medulla
The peritubular capillaries eventually reunite to form
cortical radiate (interlobular) veins, which also receive blood from the vasa recta.
The peritubular capillaries eventually reunite to form cortical radiate (interlobular) veins, which also receive blood from the vasa recta. Then the blood
drains through the arcuate veins to the interlobar veins running between the renal pyramids.
Blood leaves the kidney through
a single renal vein that exits at the renal hilum and carries venous blood to the inferior vena cava.
Many renal nerves originate
in the renal ganglion
Many renal nerves pass through the
renal plexus into the kidneys along with the renal arteries.
Renal nerves are part of the
sympathetic part of the autonomic nervous system.
Most renal nerves
are vasomotor nerves that regulate the flow of blood through the kidney by causing vasodilation or vasoconstriction of renal arterioles.
Nephrons (NEF-rons) are
the functional units of the kidneys
Each nephron consists of two parts:
a renal corpuscle (KOR-pus-el = tiny body), where blood plasma is filtered, and a renal tubule into which the filtered fluid (glomerular filtrate) passes and is further regulated
The two components of a renal corpuscle are.
the glomerulus (capillary network) and the glomerular capsule or Bowman’s capsule, a double-walled epithelial cup that surrounds the glomerular capillaries
Blood plasma is filtered in the glomerular capsule, and then
the filtered fluid passes into the renal tubule, which has three main sections
In the order that fluid passes through them, the renal tubule consists of
a (1) proximal convoluted tubule (PCT) (kon′-vō-LOOT-ed), (2) nephron loop (loop of Henle), and (3) distal convoluted tubule (DCT).
Proximal denotes
the part of the tubule attached to the glomerular capsule,
distal denotes the part that is
further away from the glomerular capsule
Convoluted means the tubule is .
tightly coiled rather than straight
The renal corpuscle and both convoluted tubules
lie within the renal cortex
the nephron loop
extends into the renal medulla, makes a hairpin turn, and then returns to the renal cortex.
