The Excretory System Ppt.

Members: Bacolod, Jonna Sanchez, Keno

Hanipah, Jenelle

Introduction • As a normal consequence of being alive, every cell in the body produces metabolic wastes includes excess water and salts, carbon dioxide and urea. Urea is a toxic compound that is produce when acids are used for energy. The process by which these metabolic waste are removed from the body is called excretion.

The job of the excretory system is to remove various produced by the body. The removal is known as excretion. It is important for the body to remove these various waste, also known as toxic, because toxic build up can lead to severe death. About sixty percent of your body contains water. A portion of the water is in the tissues and cells. The water contains salt. the salt needs to be kept at the right concentrations. If there is little salt the body feeds it more, if there is too much salt the body gets rid of the salt not needed. This is the task of the two Kidneys.

MAIN ORGAN OF THE EXCRETORY SYSTEM

• LOCATION AND STRUCTURE

Small, dark red organs with a kidney-bean shape lie against the dorsal body wall in a retroperitoneal position (beneath the parietal peritoneum) in the superior lumbar region. An adult kidney is about 12 cm (5 inches) long, 6 cm (2.5inches) wide, and 3 cm (1 inch) thick, about the size of a large bar soap. It is convex laterally and has a medial indentation called the renal hilus. Several structures, including the ureters, the renal blood vessels, and nerves, enter or exits the kidney at the hilus. Atop each kidney is an adrenal gland, which is part of the endocrine system and is a distinctly separate organ functionally.

kidneyis a homeostatic organ which maintain the purity and constancy of our internal fluids. A fibrous, transparent renal capsule encloses each kidney and gives a fresh kidney a glistening appearance. A fatty mass, the adipose capsule, surrounds each kidney and helps hold it in place against the muscles of the trunk wall.

Three distinct regions renal cortex -the outer region, which is light in color, which is the. (The word cortex comes from the Latin word meaning “bark.”) renal medulla- is a darker reddish-brown area.The medulla has many basically triangular regions with a striped appearance, the medullary pyramids. The broader base of each pyramid faces toward the cortex; its tip, the apex, points toward the inner region of the kidney. The pyramids are separated by extensions of cortex like tissue, the renal columns.

Medial to the hilus is flat, basinlike cavity, the renal pelvis. The pelvis is continuous with the ureter leaving the hilus. Extensions of the pelvis, calyces, form cupshaped areas that enclose the tips of the pyramids. The calyces collect urine, which continuously drains from the tips of the pyramids into the renal pelvis. Urine then flows from the pelvis into the ureter, which transports it to the bladder for temporary storage.

Blood Supply The arterial supply of each kidney is the renal artery. As the renal artery approaches the hilus, it divides into segmental arteries. Once inside the pelvis, the segmental arteries break up into lobar arteries, each of which gives off several branches called interlobar arteries, which travel through the renal columns to reach the cortex. At the cortex-medulla junction, interlobar arteries give off the arcuate arteries, which curve over the medullary pyramids.

Small interlobular arteries then branch off the arcuate arteries and run outward to supply the cortical tissue. Venous blood draining from the kidney flows through veins that trace the pathway of the arterial supply but in a reverse direction – interlobular veins to arcuate veins to interlobar veins to the renal vein, which emerges from the kidney hilus. (There are no lobar or segmental veins.)

Nephrons and Urine Formation Each kidney contains over a million tiny structures called nephrons. Nephrons are the structural and functional units of the kidneys and, as such, are responsible for forming urine. Each nephron consists of two main structures: a glomerulus, which is a knot of capillaries, and a renal tubule. The closed end of the renal tubule is enlarged and cup-shaped and completely surrounds the glomerulus. This portion of the renal tubule is called the glomerular, or Bowman’s, capsule. The inner (visceral) layer of the capsule is made up of highly modified octupus-like cells called podocytes. Podocytes have long branching processes called foot processes that intertwine with one another and cling to the glomerulus.

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KIDNEY STRUCTURE If a kidney is cut in half, two distinct regions can be seen, the inner part is called the renal medula, the renal cortex, and the renal cortex contains the nephrons, the basic functional units of the kidneys. Each nephrons is a small independent filtering unit. In each kidney are about 1 million nephrons.

Each nephrons has its own blood supply: an arteriole, a venule and a network of capillaries connecting them. In addition, each nephrons has its own collecting tube, which leads to the ureter. As blood enters a nephrons through an arteriole, impurities are filtered out and emptied into the collecting tube. Purified blood leaves the nephrons through a venule. The actual mechanism of blood purification is rather complex, involving two separate processfiltration and reabsorption.

URINARY SYSTEM The principal function of the urinary system is to maintain the volume and composition of body fluids within normal limits. One aspect of this function is to rid the body of waste products that accumulate as a result of cellular metabolism, and because of this, it is sometimes referred to as the excretory system.

The parts of the nephron unit include: The renal arteriole carries blood to the nephron. The Bowman’s capsule surrounds a cluster of capillary loops called the glomerulus. The glomerulus is the actual filter, which filters out water, glucose, and electrolytes. The proximal tubule reabsorbs glucose, some electrolytes and water. The loop of Henle secretes urea, reabsorbs electrolytes and water.

The distal tubule secretes ammonia, some electrolytes; some drugs, and also reabsorbs some electrolytes. The collecting duct reabsorbs electrolytes and urea. It also secretes ammonia and electrolytes. It is now concentrated urine. The renal venules then return the blood to the body.

URETERS

The ureters are two tubes 10-12 inches in length and one half inch in diameter. They are composed of smooth muscle tissue, and they extend from the renal pelvis of each kidney to the posterior portion of the urinary bladder. Their function is to conduct urine from the kidneys to the urinary bladder. At the junction where the ureters join the bladder, a valve-like structure prevents the urine from flowing back to the ureters.

URINARY BLADDER The bladder is a muscular bag-like organ that is located in the front center of the pelvic cavity. Its purpose is to store and expel urine. Normal storage capacity is about 250 ml., although it can hold up to 1000 ml. When the bladder fills, nerves in the muscular wall are stimulated, thus the urge to urinate. Micturition and to void are terms that also mean urination.

URETHRA The urethra is a tube about l to 1.5 inches in length in the female, which extends from the bladder to the outside of the body. An opening called the urinary meatus is located immediately in front of the vagina. The function of the female urethra is to transport urine to the outside. The urethra of the male is an S-shaped tube between 8 to 10 inches in length, which extends from the bladder, through the penis to the outside. The function of the male urethra is to transport urine and sperm to the outside.

URINE Urine is formed in the nephron units of the kidneys. Each minute, approximately 600 ml. of blood enters each kidney through the renal artery supply. As the blood is filtered, water, glucose, vitamins, amino acids, and salts are reabsorbed back into the bloodstream. Active transport is the process by which urine is made. Normal urine consists of 95% water, and the remaining ingredients include waste products from the breakdown of protein, hormones, electrolytes, pigments, toxins, and any abnormal components.

URINALYSIS

A urinalysis is an assessment of the urine to determine composition of urine. This test assesses the following: Color, which is normally clear and yellow, to amber or straw, colored. Cloudy urine may indicate mucus or pus in the urine. Dark urine may indicate the presence of blood or bile. Alkaline urine, which contains calcium, may appear cloudy

Renal calculus, or a kidney stone, is composed of uric acid and calcium salts. The cause of renal stones is not known, although diminished fluid intake and high intake of especially Vitamin C may contribute to the condition. Extreme pain in the area where the stone is blocked is the most common symptom. Treatment depends on the location and size of the stone. Pain management, lithotripsy (extracorporeal shock waves to disintegrate kidney stones), or perhaps surgical removal is among the treatments used for renal calculi.

FILTRATION As blood enters a nephrons through an arteriole, it flows into a small network of so separate capillaries known as a glomerulus. The glomerulus is encased in the upper end of the nephrons by a cup shaped structure called Bowman’s capsule. Because the blood is under pressure and the walls of the capillaries and Bowman’s capsule are permeable. Much of the fluid from the blood filters into Bowman’s capsule. This process is known as filtration.

The materials that are filtered from the blood are collectively called filtrate. The filtrate contains water, urea, glucose, salts, amino acids and some vitamins, because plasma proteins, cells and platelets are too large to pass through the membrane, they remain in the blood.

REABSORPTION Almost 180 liters of filtrate pass from the blood into collecting tubules each day. This volume is equivalent to 902-liters bottles of soft drink, and needles to say, not all of the 180 liters is excreted. Most of the material removed from the blood at Bowman’s capsule makes it way back into the blood by a process known as reabsorption.

URINARY SYSTEM DISORDERS • Cystitis (sis-TIE-tis): Inflammation of the urinary • • • • •

bladder caused by a bacterial infection. Glomerulonephritis (glah-mer-u-lo-ne-FRY-tis): Inflammation of the glomeruli in the renal corpuscles of the kidneys. Kidney stones: Large accumulations of calcium salt crystals from urine that may form in the kidneys. Pyelonephritis (pie-e-low-ne-FRY-tis): Inflammation of the kidneys caused by a bacterial infection. Urethritis (yer-i-THRY-tis): Inflammation of the urethra caused by a bacterial infection. Urinary incontinence (YER-i-nair-ee in-KONtinence): Involuntary and unintentional passage or urine.

Glomerulonephritis is the inflammation of the glomeruli in the renal corpuscles. It is generally caused by a bacterial infection elsewhere in the body, mostly in the throat or skin. In children, it is mostly associated with an upper respiratory infection, tonsillitis, or scarlet fever.

Kidney cancer Kidney cancer develops when cells in certain tissues in the kidneys become abnormal and grow uncontrollably, forming tumors. Kidney cancer accounts for 3 percent of cancer cases in the United States. The disease occurs most often in men over the age of forty. Men are twice as likely as women to suffer from this type of cancer.

B. Other Excretory organs 1.) Skin- excretes excess water and salts as well as a small amount of urea in the form of sweat. 2.) Lungs- Carbon hydrate breakdown produces carbon dioxide and water as its waste products; these are removed from the body through the lungs during expiration. 3.) Large Intestines- organ that removed feces. 4.) Lever- forms urea and bile