Chapter 13:Excretion Flashcards
Define excretion
The removal from organisms of waste products of metabolism and substances in excess of requirements
what is the main organ that excretes carbon dioxide
The lungs
Explain why the removal of carbon dioxide from the body is a example of excretion
Excretion is the removal of waste products of metabolism and substances in excess of requirements,and carbon dioxide is a waste product in aerobic respiration
Why is carbon dioxide realised from respiration both a waste product and a useful product for plants
-during daylight hours,the carbon dioxide produced can be used to make carbohydrates in photosynthesis
-at night,they do not photosynthesise and so carbon dioxide is a waste product.
Why should carbon dioxide be excreted
Carbon dioxide must be excreted as
-it dissolves in water easily to form an acidic solution which can lower the pH of cells
-This can reduce the activity of enzymes in the body which are essential for controlling the rate of metabolic reactions
define urea
A waste product produced in the liver,from the breakdown of excess amino acids
Define urine
A solution of urea and other waste materials in water,produced by the kidneys
Define ureter
One of a pair of tubes that carries urine from the kidneys to the gall bladder
Define urethra
The tube that carries urine from the gallbladder to the outside
What part of the kidney takes the urine to the gall bladder
The ureter
What are the substances filtered by the kidneys as blood passes through it
-urea
-excess water
-excess salts
How is urea made in the liver (8 points)
1-protein in food is taken into the alimentary canal
2-the protein molecules are broken down to amino acids during digesting
3-the amino acids are absorbed into the blood and taken to the liver in the hepatic portal vein
4-amino acids that are needed are made into proteins in the liver or released into the blood to be assimilated by body cells
5-amino acids that are not needed are delaminated to carbohydrate and a nitrogen containing compound
6-the carbohydrates are used or stored in the liver
7-the nitrogen contains part is converted into urea
8-the urea to be excreted and the amino acids to be used by the body are taken away by the blood
Define deamination
The removal of the nitrogen containing part of amino acids to form urea
Where is the kidney in the human body
At the back of the abdomen,behind the intestines
Name 4 parts of the kidneys
-cortex
-medulla
-nephron
-ureter
What is the function of kidneys
-they regulate the water content of the blood
-they excrete the toxic waste products of metabolism
Where is the nephron located
Nephrons are located between the cortex and medulla
What is a nephron
One of the thousands of microscopic tubes inside a kidney,where urine is made
What gets filtered out of the blood and into the nephron
-water
-glucose
-ions
-urea
What gets reabsorbed to the blood
-some water and ions
-glucose
What is a glomerulus
A network of blood capillaries where the blood is filtered in a kidney
What is the function for kidneys (name 2)
-they regulate the water content of the blood
-they excrete the toxic waste products of metabolism
What is a cortex
The tissue making up the outer layer in a kidney
What is a medulla
the tissue making up the inner layers in a kidney
