excretory system
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Define excretion
Process of collection and removal of harmful / useless stuff from blood, tissues, cells
What materials do humans need to excrete?
Carbon dioxide, water, salts, urea
What are the four main organs?
Liver, Lungs, Skin, Urinary System (kidneys)
The liver is an organ of excretion, but it is also an organ of ____________
Digestion
The liver’s three main excretory functions:
Detoxifies the blood, produces bile, forms urea
Sometimes the liver can become scarred. What is this called?
Cirrhosis
What is the resulting effect of cirrhosis?
Impairs liver function
How is cirrhosis caused?
Infection / poisons in the body – commonly caused by alcohol abuse.
What is the treatment of cirrhosis?
Avoid poison (avoid alcohol) and eat well.
What do the lungs excrete?
Carbon dioxide (and some water)
Lungs are not only organs of excretion, they are also important in the ______________ system.
Respiratory system
What does the skin excrete?
Sweat – salt and water
How does the skin assist in regulation of temperature?
Sweat evaporating cools skin (and thus body) Blood gets closer to skin (where it can cool down
Hair and nails are made up of dead skin cells. There is a tough protein structure that is their main component. What is it called?
Keratin
The skin is made of two layers, a thin upper layer and a thicker lower level:
Upper level: Epidermis Lower level: Dermis
What is epidermis layer made of?
Dead skin cells
Why don’t you bleed or feel pain if you cut through only the epidermis?
No blood. No nerves. No nothing. Just dead skin.
What is the kidney’s main job?
Filters waste from the blood
How big are kidneys, what do they look like, and where are they located?
Fist size, bean-shaped (kidney bean in fact!!). They lie on either side of your spine just above your waist.
What is the microscopic unit where wastes are filtered from the blood in the kidneys
Nephron
Glomerulus
A network of coiled blood vessels. Blood suppliers
From the kidney, the waste flows through ureters to the bladder. What is the waste called and what is it made of?
Urine (made of urea, water, salts, and other substances)
Ureters
narrow, muscular tubes that connect kidneys to bladder
Bladder
muscular sac that stores urine (walls of bladder expand as it fills with urine and when muscle at the neck of the bladder is allowed to relax, urine is squeezed into urethra)