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 .
