Excretiton and Homeostasis Flashcards
What is metabollic reactions?
The chemical reaction that takes place inside the cells
What is excretion
The removal of waste products of metabolism and substances in excess requirements
Explain why the removal of carbon dioxide from the body is an example of excretion.
In mammals, the carbon dioxide from respiratiob is excreted from the lungs. If it were allowed to remain in the body, it would be toxic to cells. Carbon dioxide dissolves to form a weak acid, which would lower the ph level of cells and the blood.
During the day, plants photosynthesis faster than they respire. What waste gas will they excrete, and how does this gas leave their bodies
Plants are living things, so they also excrete waste materials. During the daylight hours,plant cells can use the carbon dioxide that they produce in respiration for photosynthesis, so it is not a waste product for them during that time, however at night plants cannot photosyntesis but they can continue to respire, so the carbon dioxide is a waste product. Plants excrete carbon dioxde through their stomata.
Explain the difference between ureter and urethra
Ureter- one of a pair tubes that carries urine from the kidneys to the bladder
Urethra- The tube that carries urine from the bladder to the outside.
Explain the difference between urine and urea
Urine- A solution of urea and other waste materials in water, produced by the kidneys
Urea- A waste product produced in the liver, from the breakdown of excess amino acids
How is urea produced
Proteins are digested by your enzymes in your stomach duodenum and iluem break them down into amino acids. The amino acids are absorbed into the blood capillaries in the villi in your ileum. These blood capillaries all join up to form the hepatic portal vein, which takes the amino aicds to the liver.
The liver allows some of the amino acids to carry on while the part containing the energy is kept, turned into carbohydrate and stored. The rest, which is the part that contains nitrogen is turned into urea
The urea dissolves in blood plasma and is taken to the kidneys to excrete
What are the kidneys made of
Kidneys are made up of thousands of tiny tubules called nephrons. Each nephron begins in the cortex, loops back to medulla, back into the cortex and then goes back to the medulla. The nephrons join up with urethra
How is urine formed
Blood flows into the kidney from the renel artery. This divides to form many tiny, coiled capillaries, called glomeruli
As the blood flows through the glomeruli, it is filtered, small molecules can pass through the filter, but large molecules and blood cells cannot. The filtrate includes water, urea, glucose and ions. They all move into the nephrons
What is deamination
The removal of the nitrogen containing part of amino acids to form urea
Explain the structure of Kidney
It has two main parts the cortex and medulla. Leading away from the kidneys is a tube called urteter. The ureter carries the urine that the kidney has made from the bladder
Kidneys are actually made of thousands of tiny tubules called nephrons. Each Nephron begins with a cortex, loops down to the medulla, back to the cortex and then goes down again through the medulla. The nephrons join up with the ureter
Explain Urine Formation
Blood Flows through the kidney from the Renel Artery. This divides it into thousands of tiny coiled capillaries called glomeruli
As the blood flows through a glomerulus its filtered, Small molecules can pass through the filter, but large molecules and blood cells cannot. The filtrate (The substances tht goes through the filter) includes the water, urea, glucose and ions. These all move to the nephron
Some of these filtrate substances are toxic substances need to be lost from the body. The Urea is a toxic waste product and some water and ions may be in excess to requirements. This substances all continue through nephron
Some of these substances are not waste. The glucose in particular, is needed by the body. So is alot of the glucose, most of the water and some of the ions are taken back into the blood as the fluid flows through the nephron. This Process is called reabsorption
Define Homeostasis
The maintenance of a constant internal environment
Where is the hormones glucagon and insulin made
The pancreas is two glands in one. Most of it is an ordinary gland with a duct. It makes pancreatic juice, which flows along the pancreatic duct into the duodenum. Scattered through the pancreas, however are group of cells called islets
These cells do not make pancreatic juice. They make hormones called insulin and glucagon. These hormones help the liver to control the amount of glucose in the blood
What happens when insulin is secreted
The secretion of insulin causes to liver to absorb glucose from the blood, which reduces its concentration. The liver can use up some of this glucose in respiration, breaking it down to carbon dioxide and water. It can also change some of it to glycogen, linking many glucose molecules together into a long chain to make glycogen molecules. These can be stored in the liver cells
