also known as the renal
system, consists of the kidneys, ureters, bladder, and the urethra. Each kidney consists of
millions of functional units called nephrons.
The purpose of the renal system is to eliminate wastes from the body, regulate
blood volume and blood pressure, control levels of electrolytes and
metabolites, and regulate blood ph. The kidneys have extensive blood supply via
the renal arteries which leave the kidneys via the renal vein. Following
filtration of blood and further processing, wastes (in the form of urine) exit the kidney via the
ureters, tubes made of smooth muscle fibre’s that propel urine towards the
urinary bladder, where it is stored and subsequently expelled from the body by urination (voiding). The female and male urinary
systems are very similar, differing only in the length of the urethra. Urine is formed in
the kidneys through a filtration of blood.
The urine is then passed through the ureters to the bladder, where it is
stored. During urination, the urine is passed from the bladder through the
urethra to the outside of the body.
800-2000 millilitres (mL) of urine are normally produced
every day in a healthy human. This amount varies according to fluid intake and
kidney function.
There are several functions of the Urinary System:
·
Regulation
of acid-base homeostasis
·
Controlling blood
volume and maintaining blood pressure
KIDNEYS-are bean-shaped organs that serve several essential
regulatory roles in vertebrates.
They remove excess organic molecules from the blood, and it is by this action
that their best-known function is performed: the removal of waste products of
metabolism. Kidneys are essential to the urinary
system and also serve homeostatic functions such as the regulation of electrolytes, maintenance of acid–base balance, and regulation of blood pressure (via maintaining the salt and water
balance). They serve the body as a natural filter of the blood, and remove water-soluble wastes
which are diverted to the bladder.
In producing urine, the kidneys
excrete wastes such as urea and ammonium.
They are also responsible for the reabsorption of water, glucose, and amino acids. The kidneys also produce hormones including calcitriol and erythropoietin.
An important enzyme renin is also produced in the kidney which
acts in negative feedback.
Located at the
rear of the abdominal cavity in the retroperitoneal space, the kidneys
receive blood from the paired renal
arteries, and drain into the paired renal
veins. Each kidney excretes urine into a ureter which empties into the bladder.
Renal physiology is the study of kidney function, while nephrology is the medical specialty concerned
with kidney diseases. Diseases of
the kidney are diverse, but individuals with kidney disease frequently display
characteristic clinical features. Common clinical conditions involving the
kidney include the nephritic and nephrotic
syndromes, renal cysts, acute kidney injury, chronic kidney disease, urinary tract infection, nephrolithiasis, and urinary tract obstruction. Various cancers of the kidney exist.
The most common adult renal cancer is renal
cell carcinoma. Cancers, cysts, and some other renal conditions can be managed
with removal of the kidney. This is known as nephrectomy.
When renal function, measured by
the glomerular filtration rate,
is persistently poor, dialysis and kidney transplantation may be treatment options. Although
they are not normally harmful, kidney
stones can be extremely painful.
URETERS-In human anatomy, the ureters are tubes made of smooth muscle fibre’s that propel urine from the kidneys to the urinary bladder. In the adult,
the ureters are usually 25–30 cm (10–12 in) long and ~3–4 mm in
diameter. Histologically, the ureter contains transitional epithelium and an
additional smooth muscle layer in the more distal one-third to assist with
peristalsis. The ureters are a component of the urinary system. Urine, produced
by the kidneys, travels along the ureters to the bladder.
URINARY BLADDER is the organ that collects urine excreted by the kidneys before disposal by urination. A hollow muscular,
and distensible (or elastic) organ, the bladder sits on the pelvic floor. Urine enters the
bladder via the ureters and exits via the urethra. There is no exact
measurement for the volume of the human bladder, but different sources mention
500 mL (~17 oz.) to 1000 mL (~34 oz.). Urine, excreted by the kidneys, collects in the
bladder before disposal by urination. The urinary bladder usually holds 300-350
ml of urine. As urine accumulates, the rugae flatten and the wall of the bladder
thins as it stretches, allowing the bladder to store larger amounts of urine
without a significant rise in internal pressure.
URETHRA- In anatomy, the
urethra is a tube that connects the urinary bladder to the urinary meatus for
the removal of fluids from the body. In male placental mammals, the urethra
travels through the penis, and carries semen as well as urine. In female
placental mammals, the urethra is shorter and emerges at the female external
urethral orifice above the vaginal opening. Female placental mammals use their
urethra only for urinating, but male placental mammals use their urethra for both
urination and ejaculation. The external urethral sphincter is a striated muscle
that allows voluntary control over urination.
NEPHRON- is the basic structural and functional unit of the kidney. Its
chief function is to regulate the concentration of water and
soluble substances like sodium salts by
filtering the blood, reabsorbing what is needed and excreting the
rest as urine. A nephron eliminates wastes from the body,
regulates blood volume and blood pressure, controls levels
of electrolytes and metabolites, and regulates blood ph. Its functions are vital to life and are regulated by the endocrine system by hormones such
as antidiuretic hormone, aldosterone, and parathyroid hormone. In humans,
a normal kidney contains 800,000 to 1.5 million nephrons.
PREPARED BY: ALLEN DALE Q. VELACRUZ MW 2:30-4:00
Best information about Urinary system
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