Transcript Excretory System File

Excretory System
The Kidneys!
Facts about the Kidney
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Humans have two kidneys. They are the size of a fist.
Found in the lower back on each side of the spine.
The major waste product is urine.
At any time, 20% of the body’s blood is in the kidneys.
If for any reason a person only has one kidney, pay attention to
what is taken into his/her body as it has double the work.
Objectives 1 & 2
Homeostasis & Excretory organs.
• The excretory system maintains homeostasis by removing metabolic
wastes such as water, salt, and metabolite concentrations in the
blood.
• the lungs, the skin, and the liver.
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Lungs: removes CO2 and water vapor
Skin: removes heat, water, salts
Liver: removes metabolic wastes (eg. urea)
Objective 3 - the kidneys as organs of excretion:
• Kidneys: Functions to filter blood in order to remove cellular waste
products from the blood.
• Also controls water balance, pH, and the body’s levels of sodium,
potassium, and bicarbonate.
Objective 4 -The Urinary System
(Fig 11-17, p. 374)
Composed of Two kidneys, ureters, a urinary
bladder, and urethra.
• Ureters: Tubes that carry urine from the kidneys to
the bladder.
• Urinary bladder: A temporary storage for urine.
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Can hold about 600 ml.
When it contains 250 ml. We become aware.
• Two sphincters control urine release: one
involuntarily controlled by the brain and the other
we learn to control as children.
• Urethra: Urine exits the bladder through the
urethra. In males it is approx. 20 cm long. In
females it is approx. 4 cm.
Objective 5 - Structure of the kidney
(Fig. 11-19, p. 375)
A kidney has three major sections: the cortex,
the medulla, and the pelvis.
• Cortex: The outer layer of the kidney contains
the nephrons)
• Medulla: The inner (middle) part of the kidney
• Pelvis: Where urine accumulates before it
travels to the bladder. (an open sac)
• http://www.youtube.com/watch?v=zEpUQkQ-uKM – Urinary System
Part 1 – the kidneys (5:37)
Removal of nitrogenous wastes
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main metabolic wastes: urea, uric acid, and creatinine (all have
nitrogen as a major component).
• Urea is produced in the liver from the breakdown of amino acids (protein)
• Other waste products in the blood are uric acid, which is produced from
the breakdown of nucleic acids (DNA), and creatinine, the waste product
from muscle action.
Objective 6 – the Nephron
• ***Within the cortex and
medulla, there are approx.
one million tiny filters known
as nephrons. Each nephron
consists of five major parts:
The Bowman’s capsule, the
proximal tubule, the loop of
Henle, the distal tubule, and
the collecting duct.
Nephron Structure:
• The Bowman’s capsule: Blood enters the cavity of the ball-shaped
Bowman’s capsule through an artery that branches to form a capillary
network known as the glomerulus. Here, some plasma and small
particles are forced into the surrounding cavity while larger
components remain in the capillaries. Fluid in the Bowman’s capsule
is referred to as nephric filtrate.
• Proximal tubule: The nephric filtrate enters the proximal tubule
where materials required by the body are returned to the
bloodstream by osmosis, diffusion, and active transport. (Water,
glucose, amino acids, and ions) Tiny villi increase the surface area of
this tubule.
Nephron Structure:
• Loop of Henle: Filtrate next moves into the loop of Henle. Its main
function is to remove water from the filtrate by osmosis. The medulla
has a high sodium concentration which helps draw the water out.
• Distal tubule: Next the filtrate moves to the distal tubule, which is
responsible for tubular secretion, whereby active transport pulls
substances such as creatinine and drugs out of the blood and into the
filtrate.
• Collecting duct: Fluid from many nephrons now empty into a
common collecting duct, which carries the urine to the pelvis
• http://www.youtube.com/watch?v=k5IF1j7b3fI – nephron anatomy (5:18)
• http://www.youtube.com/watch?NR=1&feature=fvwp&v=vNvZaGcLzEo – nephron function (7:55)
Objective 7 - Excretory System Disorders (p. 379)
UTI - refers to urinary tract infection. It can occur in different places:
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Bladder – Cystitis
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Urethra – Urethritis
• More common in women than in men (urethral and anal openings are closer together in women).
• easier for bacteria from the colon to enter the urethral opening causing infection.
Symptoms:
• Frequent and/or painful urination (burning sensation)
• Bloody or brown urine
• A tender back; Chills, fever, nausea
If this infection reaches the kidneys it is referred to pyelonephritis. This can be caused by prostate
obstruction (older men), or an infection, which traveled up from the bladder (young children).
All UTIs are serious (can result in permanent damage to the kidneys, even kidney failure). Treatment is
usually by antibiotics.
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UTI Video: Nurse Describes - Causes and symptoms.http://www.youtube.com/watch?v=ixTOdlciYx8&safety_mode=true&persist_safety_mode=1&safe=active
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UTI Video: Symptoms and Prevention.http://www.youtube.com/watch?v=zHXJrGH5864&safety_mode=true&persist_safety_mode=1&safe=active
Objective 7 - Kidney Stones
• Form when chemicals in the urine precipitate out and form crystals
• More common in men than in women
Caused by:
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UTI
Insufficient water consumption
Low activity levels
Too much vitamin C and D
Symptoms include:
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Severe pain in the lower back and abdomen
Bloody urine
Nausea and vomiting
Kidney Stones: Video. http://www.youtube.com/watch?v=--nec1RQWNY&safety_mode=true&persist_safety_mode=1&safe=active
Kidney stones continued...
Treatment:
• Patients are asked to drink lots of water
• Small stones can pass through the urinary tract on their own
• Medication can help breakdown the crystals
• Lithotripsy
• Large stones may require surgery
Dialysis (p. 377)
• Hemodialysis or kidney dialysis is a procedure in which blood is removed
from an artery, purified, vital substances are added, and returned to a vein.
(fig 11-22)
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Used to treat patients with renal failure (kidney failure)
Wastes that are accumulating in the blood must be removed
These patients are usually waiting on a kidney transplant
Wastes are removed by diffusion
• Blood is pumped through the dialysis tubing, which is submersed in
dialysate.
• Waste leaves the blood and enters the dialysate by diffusion.
• Materials can be added to the blood by the same process.
• The dialysate contains a lower concentration of waste; hence waste from
the blood will move out.
Kidney Transplant Issues (p. 380)
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The first kidney transplant was 40 years ago
1112 transplants performed in Canada
The major problem is finding suitable donors; most donors are victims
of stroke or head trauma. Why?
A doctor must have permission from the victim’s family before organs
can be removed.
Do you agree with the opting out policy?
Do you feel it is right to remove a healthy person’s kidney?
Do you feel it is right for a healthy person to sell his/her kidney?
Do you agree with transplanting animal (pig) organs to humans?