Excretion System Flashcards
Define Excretion
The removal of metabolic wastes from the body.
Define Homeostasis
The maintenance of a constant internal environment of the body
A function of the excretory system
Keeping a constant body temperature, fluid balance and salt balance.
How does the excretory system play a role in homeostasis?
It keeps the body suitable for enzyme-controlled reactions.
What is an endotherm? Give an example.
Endotherms - Animals that make their own heat and maintain a constant body temperature. (E.g Mammals and Humans)
What is an ectotherm? Give an example.
Body temperature varies with environments and temperature. They gain or lose heat, depending on the external environment. (E.g. Fish)
What are the functions of the skin?
- Protection -
i) Epidermis protects against damage,
ii) Dermis protects internal organs.
iii) Melanin protects against UV rays, which cause skin cancer. - Excretion - Sweating
- Temperature regulation.
What happens to the human body when it is cold?
i) The hairs on our arms stand up, which traps warm air for insulation, helping keep the body warm.
ii) Blood vessels contract, this retains heat.
iii) We shiver which produces heat and raises our temperature.
What happens to the human body when it gets warm?
i) We sweat, which cools the body as it evaporates.
ii) Blood vessels dilate which increases heat loss.
Organs of Excretion and what they excrete.
Lungs - CO2 and H20
Kidneys- Urea, Uric Acid, Excess water and salts.
Skin - Salts, water and uric acids.
The function of the kidneys
i) Excretion of urea, excess salts and water
ii) Controls water and salt concentration of the body
iii) Controls the PH of body fluids.
Location of the kidneys…
Below the diaphragm, small of the back
Pathway of Urine from the kidney to the urethra
Kidney - Ureter - Bladder - Urethra
How does the kidney make urine?
- Blood enters the kidneys through the renal arteries.
- The kidneys filter waste and useful materials from the blood.
- Useful materials are reabsorbed from the kidneys back into the blood.
- Urine is formed in the kidney and flows to the bladder through the Ureters.
- Blood leaves the kidneys in the renal veins.
What are Nephrons?
Structures in the kidney that make urine. Each kidney has over 1 million.
3 process in Urine Production
Filtration - in Glomerulus
Reabsorption - PCT, Loop of Henle, DCT, and collecting ducts
Secretion - In pelvis
3 process in Urine Production
Filtration - in Glomerulus
Reabsorption - PCT, Loop of Henle, DCT, and collecting ducts
Secretion - In the pelvis
Describe Filtration
Takes place in the Glomerulus. Glucose, amino acids, vitamins, urea, and salts are filtered out of the blood into the
Describe Reabsorbtion.
(Substances taken from the filtrate back into the blood.)
In the PCT, water, most salts and other useful substances, are reabsorbed by diffusion and transported by the blood.
Loop of Henle, Distal Tubule, Collecting duct all reabsorb water.
What happens to urea?
It is not reabsorbed back into the blood
What forms urine, and where does it go?
Urea, water and salt all form urine, and it passes into the collecting duct.
Define Osmoregulation
It is an example of Homeostasis. A hormone called ADH controls the volume of water reabsorbed in the collecting ducts.
Where is ADH produced?
The Pituitary Gland
What is secretion?
The release of urine from the urethra.
What is the difference between the ureter and urethra?
Ureter - Brings urine to the bladder
Urethra - Releases Urine
What is the difference between the kidney and the bladder?
Kidney- Makes Urine
Bladder- Holds Urine
What part of the brain detects changes in our temperature?
Hypothalamus
The concentration of glucose is the same in plasma and glomerular filtrate, why?
Glomerular Filtrate is plasma without large proteins.
What is plasma?
The largest part of our blood, contains, Water (90%), Proteins, (7%), and Dissolved Materials (3%)
What is Glomerular Filtrate?
Plasma without large proteins.
In what part of the nephron does filtration take place?
Glomerulus
In what part of the nephron does reabsorption of amino acids take place?
Proximal Convoluted Tubule
Name the parts of the Nephron.
Afferent arteriole
Osmosis Experiment
- Soften 2 strips of visking tubing in water
- Tie a knot at one end of each strip
- Fill one piece of tubing half way with sucrose solution (80% sucrose, 20% water) and the other with distilled water (100% water). This is the control
- Get rid of air from the tubs, and tie a knot at the open end
- Wash off any remaining sucrose solution on the outside of tubes, then pat dry.
- Record the turgidity of each tube, and record the mass of each tube
- Suspend each tube in distilled water for 20 mins. After 20 mins remove from the water and dry them
- Record the turgidity of each tube and the mass of each tube. Compare with before the experiment.
