Module 5.2 Flashcards
what is excretion
the removal of metabolic waste from the body
what is metabolic waste
a substance that is produced in excess metabolic processes in the cells , it may become toixc .
what products must be excreted
almost al products that are formed in excess by the chemical processes occuring in the cell must be removed from the body , so that they do not build up and inhibit enzyme activity or become toxic .
main excretory products are
-carbon dioxde from respiration
- nitorgen contaianig n compounds such as urea
other compounds such as the bile pigments found in feaces .
do no confuse EXCRETION WITH POOOPPYYY
Egestion is the elimination of the feaces from the body . Faces are the undigested remsains of food that are not metabolic products
excretory organ LUNGSS -what is it wxtection
carbondioxide - apssed from the cells of respiring tissues int o the bloodstream where i is transported mostly int he form of hydrogen carbonate iions to the lungs , int he lungs the carbondioxide diffuses into the alveloi to be excreted as you breathe out .
excretory organs - the liver
the liver is directly involved in excretion , it has manay metabolic roles , and some of the substances produces will be passed into the bile for excretion , with the faces , for example the pigment bilirubin .
excretory organs - the liver - what else is it involved in
the liver is also invovled in converting excess aminoa cids to urea . Aminoa cids are broken down by the proces of deamiantion . The ntiorgen contaianig aprt of the moelcule is then combined iwth carbondioxide to make urea .
exvretory organ - kidneys - what does it excrete
the urea is passed into the bloodstream to be transported to the kdineys . Urea is transproted in solution - dissolved injt he plasma . In the kidneys , the urea is removed fromt he blood to become part of the urine . Urine is stored in the bladder before being excreted fromt he bod via the urethra .
excretory organa - rhe skin - wht does it excrete
the skin s also involved in excrtetion but excretion is not the primar function of the skin . Sweat contains a range of substances including salts ure , water uric aicfd nd mmonia . Urea , uric acid and mmonia are all excreotry products . The loss of water nd salts my be important part of hoemostiss 0 mainti body temp and water potential of the blood .
what is the importance of excretion
allowing the products of metabolism to build up could be fatal as some metabolic rpoducts ilek co2 is toixc t hey inerfre with cell rpcoresses by altering hte ph that normal metbaolism is rvented and other metabolic porducts may ct as inhibtors and reduce the actiivt of essential enzmes .
how is most carbondioxide transported in the blood as
hdyrogen carbonte tions .
but also form hdyorgen ions check page .
-this occurs inside the red blood cells under the infleunce of the enzzyme cabronic anhydrase bt can also occur in the blood plasma .
how can hdyorgen ions affect the pH of the cytoplasm in the red blood cells .
the hdyorgen ions interact with bonds within haemoglobin , changing its three dimensional shape . THIS reducs the affinit of haemoglobin for oxygen affecting oxygen transport .
how can hdyorgen ions affect the pH of the cytoplasm in the red blood cells . (2)
the hdorgen ions can then combine with haemoglobin forming the hemoglbonic acid . The carbondioxide that is not converted to hdyrogen carbonate ions can combine direclty with hemoglobn , producing carboaminohaemoglobin . Bothhaemoglobinic acid and carbaminohaemoglobin are unable to combine with oxygenn as normal reducing oxygen tranasport further .
why is maintainig the ph of the blood plasma essential
becuse changes could alter the structure of the many proteins int he blood that helps to transprot a wide range of substances aroudn the bod . Porteins int he blood act as buffers to resit the change in PH .
What hapens if the change in pH is small
then the extra hdyorgen ions are dected by the respriatory center int he medulal obongata of the brain , causing an increase in breahing rate to help to remove the excess carbondixoide .
hat hapens if the blood pH droops below 7.35
it cuses headaches , dorwsiness , restlessness ,t reor and foncusion . There may also e rapid heart rate and changes in blood pressure , this is RESPIRATORY ACIDOSIS , it can be caused b disease or codnitons tha affect the liungs themsleevs ,s ucha s emphsyemea , chronic bronchitis astha or severe onemonia , nbocage o the airway due o swelling of a forein objec tor vomit cn also idnce acute resiprotary acidosis
can the body store nitrogenous compoudns (1)
the body cannot store excess amino acids . However , amino acids contain almost as much enegy as carbodhyrates . Therefore it ould be wasreful simply toe xcrete excess aminoa cids , instead they are transported to the liver nd the potenitally oxic amina cids groups ir remoced (deamiantion )
can the body store nitrogenous compoudns (1)
check page 25 for equation for deaminaiton and
deamanation for urea
and firmation of urea
The amino gorp intially forms the very soluble and highly toxic compound , mmonai . This is converetd to a less soluble and less toxic compoud called urea , which can be rnspored to the kidneys for be converted to carbohdyrate or fat for storage .
Why does the liver need a good blood supply
The liver cekks carry out many hundreds of metabolic processes so the liver has an important role in homeostasis . It is therefore essential thst thr liver has s good supply of blood
What does thr internal structure of the liver ensure for good blood supply
It ensures that as much blood as possible flows past as many liver cells as possible . This enables the liver cells to remove excess or unwanted substances from thr blood snd return substances to the blood to ensure concentrati9ns are maintained .
How does the HEPATIC ARTERY supply thr liver with blood
The hepatic artery oxygenated blood from the heart travels from thr aorta via the hepatic artery into the liver . This supplies the oxygen that is essential for aerobic respiration .
Why are the liver cells very active
The liver cells are very active because they carry out many metabolic processes . Many of these processes require energy in thr form of ATP so it in important that the liver is a good supply of oxygen for aerobic respiration .
Another blood supply to the liver is the HEPATIC PORTAL VEIN
The hepatic portal vein , deoxygenated blood from the digestive system enters the liver via the hepatic portal vein . This blood is rich in the products of digestion . The concentrations of various substances will be uncontrolled as they have just entered the body from the products of digestion in the intestines .
The hepatic portal vein (2)
The blood may also contain toxic toxic compounds that have been absorbed from the intestine . It is impritwjtnthat such substances do not continue to circulate around the body before their concentrations have been adjusted .
How does blood leave the liver
Via the hepatic vein . The hepatic vein rejoins the vena cava and blood returns to the body’s normal circulation .
A fourth vessel is connected to the liver what does it do
I
This is the bile duct . Bile is a secretion from the liver which has vessels it is the bile duct. Bile is a secretion from thr liver which has functions in digestion and excretion . The bile duct carries a bile from the liver to the gall bladder , where it is stored until required to aid the digestion of fate in the small intensities .
Bile also contains excretory products
Bile also contains some excretory products such as bile pigments like bilirubin which will leave the body with the faeces .
How is the structure of the liver arranged
The cells blood vessels and chambers inside thr liver cekks . The liver is divided into lobes which are further divided into lounukes which are YLINDRIFWL .
How blood passes through the liver
As the hepatic artery and hepatic portal vein enter the liver , they split into smaller and smaller vessels . Are known as inter lobular vessels .
How blood is transported in the liver (2)
At intervals , branches from the hepatic artery and the hepatic portal vein enter vein enter thr lobules . These vessels run blood from thr two blood vessels is ,iced and passes along special chamber called ansinusoid , which is lined with liver cells . As the blood flows along the sinusoid it is in close contact with the liver cells . These cekks are able to to remove substances from thr b,kf snd return other exuberance’s to thr blood .
What are kupifer cells
Specialised macrophages called kupifer cells move about within the sinusoid . Their prow,Roy functions appears to be to breakdown and recycle old red blood cells . One of the products of hameoglobin breakdown is bilirubin , which is one of the bile pigments excreted as part of the bile .
How is bile made snd produced
Bile is made in thr liver cells and is released into the bile csnaliculi the bile is canaculi join together to form thr bile duct m which transports bile into the gall bladder .
What Happens when blood reaches the end of the sinusoid
The concentrations of many of its components have been modified snd regulated . At the Center of each lobule is a branch of the hepatic vein known intralobular vessel . The sinusoid , empty into this vessels . The branched of the hepatic vein from different lobules join together to form the he
Attic vein which drains blood from the liver .
Check figure 4 page 27
Arrangements of cells in a lobules
Describe the structure liver cells
Liver cells or hepatocytes appear to be relatively unspecialised . They have a simple cuboidal shape with many microfilm kn their surface . However , their many metabolic functions include protein synthesis .
Describe the liver cells (2)
However , their metabolic functions include,UFE protein synthesis transformation and storage of carbohydrates synthesis of cholesterol and bile salts detoxifications and many other processes . This. Dan’s thst their cytoplasms must be very dense snd is specialised in the number of certain organelles it contains .
What is an ornithine cycle
A series of biochemical reactions thst converted ammonia to urea .
Many metabolic functions of liver (1)
-controls of blood glucose levels amino acid levels lipid levels .
- synthase or bile plasma proteins and cholesterol
- synthesis kf red blood cells in the foetus .
Many metabolic functions (2)
Storage of vitamins A and D and B12 iron glycogen .
Detoxification of alcohol drugs
Breakdown of hormones
Destruction of red blood cells .
In depth about the liver storing glyocen
Liver stores sugar in the form of glycogen . It is we,e to store approximately 10l-120 of glycogen , which makes Jo to 8 perfect kf of thr fresh drjght of thr liver ,
Storage of glycogen
How does glycogen form granules , in the cytoplasms kf the hepwtocytes . This glycogen can be broken down to re,essentially glucose into the blood as required . The control of blood glucose concentrations is described .
What does the liver detoxify
One important role of thr liver is to detoxify substances thst may cause harm . Some of these compounds such as hydrogen peroxide are produced in thr body . Others such as alcohol may be consumed as part of our diet may be taken for health and recreational response , for example medicines .
How can toxins be rendered
Toxins can be rendered by harm,Ed’s by oxidation reduction methylation or by combination which another molecule . Liver cells contain an Andy,es thst render toxic molecules led toxic ,
Detoxifying liver enzyme one
Catalase , which concerts hydrogen peroxide , to oxygen snd water . Catalase , has a particularly high turnover number (the number of molecules of hydrogen peroxide thst one molecule of catalase can rodent harm,ess in one seconds ).
Detoxyfing liver enzyme two
Cytochrome p40 which is a group of enzymes used to breakdown drugs including cocaine snd various medicinal drugs . The cytochrome are also hsed in other metabolic reactions such as electron transport during reeilriarion .
Their role in metabolic,sims dehgs can interfere with other metabolic roles as cause the unearned side effects in some other medicinal drugs Breakdown of.
Interesting fact obt alcohol
Alcohol or ethanol is a drug that depresses nerve acidity in addition to, alcohol contains chemical potential energy potential. Energy which can be used for respiration .
How is alcohol broken down in thr liver (1)
Alcohol is broken down by in the hepatocytes by the action of the enzyme ethanol dehydrogenase . The resulting compounds is ethanol . This is dehydrogenase’s further by the enzymes Ethan’s, dehydrogenase .
How is alcohol broken down in the liver (2)
The final compound produced is ethanoate acetate . This acetate is combined with coenzyme A to form acetylene coenzyme A, whuch enters the process of aerobic respiration . The hydrogen atoms released from alocihol are combined with another conesyme called NAD , to form reduced NAD . ADEROXIFICSTION OF ALCOHOL FIGURE 1
NAD is required for what in thr liver
It is required to oxidise and breakdown fatty acids for use in respiration .
What if the liver has detoxify too ,cut alcohol
It uses up its store of NAD and has in sufficient left to deal with thr fatty acids for. These fatty acids are then converted back to lipids snd stored as fat in the hepatocytes causing thr liver to become enlarged this condition is known as fatty liver which can lead to slcjol related hepatitis or to cirrhosis .
Formation of urea (1)what can happen to e Cessna amino acids
Excess amino acids cannot be stored because the amino grill makes them toxic ..nhiwever , thr amino acid molecules contain a lot of energy so it
Formation of ureas 2
would be wasteful to excrete the whole molecule . Therefore , excess amino acids undergo treatment in the liver to remove and excrete the amino component . This treatment consist kf two process deamjnjantikn by the krnjthjne cycle,e .
Figure2 of 29
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How does deamination
The process of deamination remove the amino group and produces ammonia. Ammonia is very soluble and highly toxic and therefore ammoniamustnkt be allonwed to accumulate .
DESMINATIIN also produces an organic compound a kerosene acids which can enter respiration directly to release its energy.
As ammonia is soluble and toxic it must be converted to a less toxic for very quickly . Ornithine
The ammonia is combined with carbon dioxide to produce urea , . This occurs in thr ornithine cycle . Ammonia and carbon dioxide combine with the amino acids ekrnithi etoproduce citrus line. This is converted to arginine by addition of further ammonia . The arginine is the recovered to ornithine by the removal urea .
How is urea passed into the bloodline
Urea is both less soluble and less toxic than ammonia . It can be passed back into the blood , and transported around the body to the kidneys . In the kidneys the urea is fjkrered out of thr blood and concentrated in thr Rhine . Urine can be safely stored in the bladder jr is released from thr body .
Figure 4 k. Page w29
Summary of the ornithine cycle
meaning of nephron
the functional unit of the kidney
