Wednesday, October 18, 2017


Ini saya share soal soal Essay untuk persiapan Ujian Nasional karena saya mendengar akan diperbanyak soal Essay untuk Ujian Nasional ini katanya untuk memacu anak anak berfikir lebih nalar. Ya sudah ini moga moga bisa menyelesaikan OK Terima kasih 


1. What is excretion?

  • In Physiology, excretion is the process of the elimination of metabolic wastes and other toxic substances from the body.
2. What are nitrogenous wastes?
  • Nitrogenous wastes are residues produced by the degradation of proteins. They are produced by chemical transformations in the amine group of amino acid molecules.
3. What are the three main types of nitrogenous wastes excreted by living organisms?
  • The main nitrogenous wastes excreted by living organisms are ammonia, uric acid and urea. 
  • Living organisms that secrete ammonia are called ammonotelic. 
  • Organisms that secrete uric acid are called uricotelic. 
  • Organisms that secrete urea are called ureotelic. 
4. Why are most ammonotelic organisms aquatic animals?
  • Aquatic animals, such as crustaceans, bony fish and amphibian larvae, are generally ammonotelic because ammonia diffuses more easily through membranes and is more water-soluble than the other types of nitrogenous waste. 
  • Ammonia is still the nitrogenous waste most economical to synthesize in terms of energy.
5. Why did ammonotelic excretion cease to be used after animals left aquatic habitats and started to live in terrestrial habitats?
  • Ammonia is a highly toxic molecule if not diluted and quickly excreted from the body. 
  • For this reason, ammonotelic excretion was abandoned in terrestrial habitats because the availability of water for dilution was reduced in this medium, making it so that waste could not be excreted to the exterior so quickly.
6. With regards to toxicity and the need for dilution in water, how different are ureotelic and uricotelic excretions? What are some examples of animals that use these types of excretion?
  • Urea is more water-soluble than uric acid (an almost insoluble substance). 
  • Urea is also more toxic. However, both are less toxic than ammonia. 
  • Some invertebrates, chondrichthyan fish, adult amphibians and mammals are ureotelic. Reptiles, birds and most arthropods are uricotelic.
7. What is the nitrogenous waste produced by amphibian larvae and by the adult animal?
  • Since amphibian larvae are aquatic, they excrete ammonia. The terrestrial adult excretes urea.
8. Why is uricotelic excretion essential for avian and reptile embryos?
  • In reptiles and birds, the excretory system is uricotelic since uric acid is insoluble, less toxic and suitable to be stored within the eggs where their embryos develop.
9. How do the embryos of placental mammals excrete nitrogenous wastes?
  • Placental animals, including embryos, excrete urea. 
  • In the adult placental mammal urea is excreted through the urine. 
  • In embryos, the molecule passes to the mother’s blood through the placenta and is excreted in the mother’s urine. 
10. What is the main nitrogenous waste produced by humans?
  • Human beings excrete mainly urea, which is eliminated in urine.
11. How is urea formed in the human body?
  • Urea is a product of the degradation of amino acids. 
  • During this process, amino acids lose their amine group, which is then transformed into ammonia. 
  • In the liver, ammonia reacts with carbon dioxide to form urea and water, through a process called ureogenesis. 
  • During the intermediary reactions of ureogenesis, a molecule of ornithine is consumed and another is produced. For this reason, ureogenesis is also known as the ornithine cycle.
12. What organs make up the excretory system?
  • The excretory system is formed of the kidneys (two), the ureters (two), the bladder and the urethra. 
13. The arterial vessels that carry blood to be filtered by the kidneys are the renal arteries. 
  • The renal arteries are branches of the aorta; therefore, blood filtered by the kidneys is arterial (oxygen-rich) blood. 
14. Which vessels drain filtered blood from the kidneys?
  • The venous vessels that collect blood filtered by the kidneys are the renal veins. 
  • The renal veins carry blood that has been reabsorbed by the nephron tubules.
15. What is the functional unit of the kidneys?
  • The functional (filtering) unit of the kidneys is the nephron. 
  • A nephron is made of the afferent arteriole, the efferent arteriole, the glomerulus, the Bowman's capsule, the proximal tubule, the loop of Henle, the distal tubule and the collecting duct.
16. What are the three main renal processes that produce urine when combined?
  • Urine is made by these occurrence of three processes in the nephron: glomerular filtration, tubular reabsorption and tubular secretion. 
  • In the nephron, blood carried by the afferent arteriole enters the glomerular capillary network where it is filtered. 
  • The filtration results in part of the blood returning to circulation through the efferent arteriole while the other part, known as glomerular filtrate, enters the proximal tubule of the nephron. 
  • In the nephron tubules (also known as convoluted tubules), substances of the glomerular filtrate, such as water, ions and small organic molecules, are reabsorbed by the cells of the tubule wall and enter into circulation. \
  • These cells also secrete other substances inside the tubules. 
  • Urine is formed of filtered substances that are reabsorbed and of secreted (by the tubules) substances. 
  • Urine is drained by the collecting ducts to the ureter of each kidney. 
  • It then enters the bladder and is later discharged through the urethra.  
  • The nephron tubules are surrounded by an extensive capillary network that collects reabsorbed substances and supplies others to be secreted.

17. What is the main transformation presented in glomerular filtrate compared to blood?

  • Glomerular filtrate is the name given to plasma after it has passed the glomerulus and entered the Bowman’s capsule. 
  • Glomerular filtrate has a different composition compared to urine, since the fluid has not yet undergone tubular reabsorption and secretion. 
  • The main difference between blood and glomerular filtrate is that the latter contains a minimum amount of proteins as well as no cells or blood platelets.
18. What is proteinuria? Why is proteinuria a sign of glomerular renal injury?
  • Proteinuria means the passing of proteins in the urine. Under normal conditions, proteins are too large to be filtered by the glomerulus and are practically absent in urine (the few filtered proteins may also be reabsorbed by the nephron tubules). 
  • Proteinuria is an indication that a more than expected amount of proteins is passing through the glomerulus, and is an indicator of glomerular disease, such as diabetic nephropathy. 
  • The glomerulus also blocks the passage of blood cells and platelets (hematuria is often a sign of urinary disease, although it does not specifically implicate the kidneys, since the blood may come from the lower parts of the excretory tract).
19. Where does most of the water reabsorbed after glomerular filtration go? What other substances are reabsorbed by the nephron tubules?
  • Only 0.5 to 1% of glomerular filtrate is eliminated as urine. 
  • The remaining volume, containing mainly metabolic ions, glucose, amino acids and water, is reabsorbed by the nephron tubules (by means of active or passive transport) and regains blood circulation.
20. Why do the cells of the nephron tubules contain a large amount of mitochondria?
  • The cells of the tubule wall have a large number of mitochondria because many substances are reabsorbed or secreted through them by means of active transport (a process that spends energy). 
  • Therefore, many mitochondria are necessary to supply the energy for (ATP supply) this type of transport.
21. What is tubular secretion? What are some examples of substances secreted through the renal tubules?
  • Tubular secretion is the passage of substances from the blood capillaries that surround the nephron tubules to the tubular lumen so that these substances can be excreted with urine. 
  • Ammonia, uric acid, potassium, bicarbonate and hydrogen ions, metabolic acids and bases, various ingested drugs (medicines) and other substances are secreted by the nephron tubules.
22. In what part of the nephron does the regulation of the acidity and alkalinity of plasma take place?
  • The regulation of the acid-basic equilibrium of the body is carried out by the kidneys and depends on tubular reabsorption and secretion.
23. How are kidneys involved in the regulation of the acid-basic equilibrium of the body? 
  • How are alkalosis and acidosis corrected by the kidneys?
  • The kidneys can regulate the acidity or alkalinity of the plasma by varying the excretion of hydrogen and bicarbonate ions. 
  • During alkalosis (an abnormally high level of plasma pH), the kidneys excrete more bicarbonate ions and the equilibrium of the formation of bicarbonate from water and carbon dioxide shifts towards the formation of more hydrogen ions and bicarbonate ions, thus lowering plasma pH. 
  • When the body undergoes acidosis (an abnormally low level of plasma pH), the kidneys excrete more hydrogen ions and retain more bicarbonate ions and, as a result, the equilibrium of the formation of bicarbonate from water and carbon dioxide shifts towards more hydrogen consumption, increasing the pH of plasma.

24. How are the kidneys involved in controlling blood volume? How is the volume of blood in the body related to arterial pressure?

  • The kidneys and the hormones that control them are the main physiological regulators of the total volume of blood in the body. 
  • As more water is reabsorbed by the nephron tubules, the volume of blood increases and, as more water is excreted in urine, the volume of blood lowers. 
  • The volume of blood in turn has a direct relationship with blood pressure. Blood pressure increases when blood volume increases and it lowers when blood volume lowers. 
  • This is the reason why one of the main groups of antihypertensive drugs is diuretics. 
  • Doctors often prescribe diuretics to patients with high blood pressure so that they excrete more water and therefore lower their blood pressure.
25. Which three main hormones are involved in the regulation of the renal function?
  • Antidiuretic hormone (ADH, or vasopressin), aldosterone and atrial natriuretic factor (or ANF) are the mains hormones that are involved in the regulation of the excretory system.
26. What is the function of antidiuretic hormone? Where is it produced and what stimuli increase or decrease its secretion?
  • Antidiuretic hormone is secreted by the hypophysis (also known as the pituitary gland) and it has an effect on the nephron tubules, increasing their reabsorption of water. 
  • When the body needs to retain water, for example, in the case of blood loss and an abrupt decrease in blood pressure, or in the case of an abnormally high blood osmolarity, ADH secretion is stimulated. 
  • When the body has an excess of water, such as in the event of excessive ingestion or abnormally low blood osmolarity, the secretion of ADH is blocked and diuresis increases. 
  • ADH is also known as vasopressin since it increases blood volume and therefore increases blood pressure.
27. Why does the ingestion of alcohol increase diuresis?
  • Alcohol inhibits the secretion of ADH (antidiuretic hormone) by the pituitary gland. That is why when people are drunk, they urinate in excess.
28. What is the effect of aldosterone and where is it produced?
  • Aldosterone is a hormone that has an effect on the nephron tubules, stimulating the reabsorption of sodium. 
  • Therefore, it contributes to increasing blood osmolarity, consequently increasing blood pressure.
  • Aldosterone is made by the adrenal glands, which are located above the upper portion of the kidneys.

29. What evolutionary hypothesis could explain the heart’s role in secreting a hormone that regulates renal function? What hormone is this?

  • The renal regulator hormone secreted by the heart is atrial natriuretic factor (or ANF). 
  • ANF increases the excretion of sodium in the nephron tubules, causing less reabsorption of water and more urinary volume, thus lowering blood pressure. 
  • Atrial natriuretic factor is secreted when there is an increase in the length of heart muscle fibers in response to high blood pressure. ANF is a natural antihypertensive substance. 
  • Since the health of the heart depends largely on the stability of normal blood pressure, evolution likely preserved atrial natriuretic factor to allow information from the heart to work as an additional mechanism in the renal control of blood pressure.



1. What are the main functions of blood?

  • Blood is a means of substance transportation throughout the body. 
  • Blood distributes nutrients, oxygen, hormones, antibodies and cells specialized in defense to tissues and collects waste such as nitrogenous wastes and carbon dioxide from them.
2. What elements make up blood?
  • Blood is made of a liquid and a cellular portion. 
  • The fluid part is called plasma and contains several substances, including proteins, lipids, carbohydrates and mineral salts. 
  • The cellular components of blood are also known as blood corpuscles and they include erythrocytes (red blood cells), leukocytes and platelets.
3. What is hematopoiesis?
  • Hematopoiesis is the formation of blood cells and the other elements that make up blood.
4. Where does hematopoiesis occur?
  • Hematopoiesis occurs in the bone marrow (mainly within flat bones), where erythrocytes, leukocytes and platelets are made; and in lymphoid tissue, which is responsible for the maturation of leukocytes and which is found in the thymus, spleen and lymph nodes.
5. In which bones can bone marrow chiefly be found? Is bone marrow made of bone tissue?
  • Bone marrow can mainly be found in the internal cavities of flat bones, such as vertebrae, the ribs, the shoulder blades, the sternum and the hips. 
  • Bone marrow is not made of bone tissue, although it is a connective tissue just like bone tissue.
6. What are blood stem cells?
  • Stem cells are undifferentiated cells able to differentiate into other types of specialized cells. 
  • The stem cells of the bone marrow produce differentiated blood cells. 
  • Depending on stimuli from specific growth factors, stem cells are turned into red blood cells, leukocytes and megakaryocytes (the cells that form platelets). 
  • Research shows that the stem cells of the bone marrow can also differentiate into muscle, nervous and hepatic cells.
7. What are the other names for erythrocytes? What is the function of these cells?
  • Erythrocytes are also known as red blood cells (RBCs) or red corpuscles.
  • Red blood cells are responsible for transporting oxygen from the lungs to tissues.
8. What is the name of the molecule in red blood cells that transports oxygen?
  • The respiratory pigment of red blood cells is called hemoglobin.
9. What is the molecular composition of hemoglobin? Does the functionality of hemoglobin as a protein depend on its tertiary or quaternary structure?
  • Hemoglobin is a molecule made of four polypeptide chains, each bound to an iron-containing molecular group called a heme group. Therefore, the molecule contains four polypeptide chains and four heme groups. 
  • As a protein composed of polypeptide chains, the functionality of hemoglobin depends upon the integrity of its quaternary structure.
10. On average, what is the lifespan of a red blood cell? Where are they destroyed? Where do heme groups go after the destruction of hemoglobin molecules?
  • On average, red blood cells live for around 120 days. The spleen is the main organ where old red blood cells are destroyed. 
  • During the destruction of red blood cells, the heme groups turn into bilirubin and this substance is then captured by the liver and later excreted to the bowels as a part of bile.
11. What are the functions of the spleen? Why can people still live after a total splenectomy (surgical removal of the spleen)?
  • The spleen has many functions: it participates in the destruction of old red blood cells; in it specialized leukocytes are matured; it helps regenerate the hematopoietic tissue of bone marrow when necessary; and it can act as a sponge-like organ to retain or release blood into circulation. 
  • It is not impossible to live after a total splenectomy because none of the functions of the spleen are both vital and exclusive to this organ.
12. What is anemia? What are the four main types of anemia?
  • Anemia is a low concentration of hemoglobin in the blood. 
  • The four main types of anemia are nutrient-deficiency anemia, anemia caused by blood loss, hemolytic anemia and aplastic anemia.
  • Nutrient-deficiency anemia is caused by a dietary deficiency in fundamental nutrients necessary for the production or functioning of red blood cells, such as iron (iron deficiency anemia), vitamin B12 and folic acid.
  • Anemia caused by blood loss occurs in hemorrhagic conditions or in diseases such as peptic ulcerations and hookworm disease.
  • Hemolytic anemia is caused by the excessive destruction of red blood cells, for example, in diseases such as malaria or in hypervolemic conditions (excessive water in blood causing lysis of red blood cells).
  • Aplastic anemia occurs from deficiencies in hematopoiesis and occurs when bone marrow is injured by cancer from other tissues (metastasis), by autoimmune diseases, by drug intoxication (such as sulfa drugs and anticonvulsants) or by chemical substances (such as benzene, insecticides, paints, herbicides and solvents in general). Some genetic diseases also affect bone marrow, causing aplastic anemia.
13. What is the difference between white and red blood cells? What are leukocytes?
  • Red blood cells are called erythrocytes and white blood cells are called leukocytes. 
  • Leukocytes are cells specialized in the defense of the body against foreign agents and are part of the immune system.
14. What are the different types of leukocytes and how are they classified into granulocytes and agranulocytes?
  • The types of leukocytes are lymphocytes, monocytes, neutrophils, eosinophils and basophils. 
  • Granulocytes are those with a cytoplasm that contains granules (when viewed under electron microscopy): neutrophils, eosinophils and basophils are granulocytes. 
  • Agranulocytes are the other leukocytes: lymphocytes and monocytes.
15. What is the generic function of leukocytes? What are leukocytosis and leukopenia?
  • The generic function of leukocytes is to participate in the defense of the body against foreign agents that penetrate it or are produced inside the body. 
  • Leukocytosis and leukopenia are clinical conditions in which a blood sample contains an abnormal count of leukocytes. 
  • When the leukocyte count in a blood sample is above the normal level for the individual, it is called leukocytosis. 
  • When the leukocyte count is lower than the expected normal level, it is called leukopenia. 
  • The multiplication of these defense cells, leukocytosis, generally takes place when the body is suffering from infections or in cancer of these cells. A low count of these defense cells, or leukopenia, occurs when some diseases, such as AIDS, attack the cells or when immunosuppressive drugs are used.
  • In general, the body uses leukocytosis as a defense reaction when it is facing infectious or pathogenic agents. 
  • The clinical condition of leukocytosis is therefore a sign of infection. 
  • Leukopenia occurs when there is a deficiency in the production (for example, in bone marrow diseases) or excessive destruction of leukocytes (for example, in the case of HIV infection).
16. What are the mechanisms to contain hemorrhage called? 
  • The physiological mechanisms to contain hemorrhage (one of them is blood clotting) are generically called hemostasis, or hemostatic processes.
17. How are platelets formed? What is the function of platelets? What are the clinical consequences of the condition known as thrombocytopenia?
  • Platelets, also known as thrombocytes, are fragments of large bone marrow cells called megakaryocytes. 
  • Through their properties of aggregation and adhesiveness, they are directly involved in blood clotting as well as release substances that activate other hemostatic processes. 
  • Thrombocytopenia is a clinical condition in which the blood platelet count of an individual is lower than normal. In this situation, the person becomes susceptible to hemorrhages.
18. How does the body know that the coagulation process must begin?
  • When tissue wound contains injury to a blood vessel, the platelets and endothelial cells of the wall of the damaged vessel release substances (platelet factors and tissue factors, respectively) that trigger the clotting process.
19. How can the blood coagulation (clotting) process be described?
  • Blood clotting encompasses a sequence of chemical reactions whose products are enzymes that catalyze the subsequent reactions (that is why clotting reactions are called cascade reactions). 
  • In the plasma, thromboplastinogen transforms into thromboplastin, a reaction triggered by tissue and platelet factors released after injury to a blood vessel. 
  • Along with calcium ions, thromboplastin then catalyzes the transformation of prothrombin into thrombin. 
  • Thrombin then catalyzes a reaction that produces fibrin from fibrinogen. Fibrin, as an insoluble substance, forms a network that traps red blood cells and platelets, thus forming the blood clot and containing the hemorrhage.
20. What are clotting factors?
  • Clotting factors are substances (enzymes, coenzymes, reagents) necessary for the clotting process to happen. 
  • In addition to the triggering factors and reagents already described (tissue and platelet factors, thromplastinogen, prothrombin, fibrinogen, calcium ions), other substances participate in the blood clotting process as clotting factors. 
  • One of these is factor VIII, the deficiency of w
21. In what organ are most of the clotting factors produced? What is the role of vitamin K in blood coagulation?
  • Most clotting factors are produced in the liver. 
  • Vitamin K participates in the activation of several clotting factors and is essential for the proper functioning of blood coagulation.
22. What is factor VIII? What is the genetic disease in which this factor is absent?
  • Factor VIII has the function of activating factor X, which in turn is necessary for the transformation of prothrombin into thrombin during the clotting cascade. 
  • Hemophilia A is the X-linked genetic disease in which the individual does not produce factor VIII and as a result is more susceptible to severe hemorrhages.
23. How is hemophilia treated? Why is hemophilia rare in females?
  • Hemophilia is medically treated with the administration of factor VIII, in the case of hemophilia A, or of factor IX, in the case of hemophilia B, by means of blood or fresh frozen plasma transfusions. 
  • Both hemophilia A or B are X-linked recessive diseases. 
  • For a girl to be hemophilic, it is necessary for both of her X chromosomes to be affected whereas boys, who have only one X chromosome, are more easily affected. 
  • A girl with only one affected chromosome does not present the disease, since the normal gene of the unaffected X chromosome produces the clotting factor.
24. What is the epidemiological association between hemophilia and HIV infection?
  • Since hemophilic patients need frequent transfusions of clotting factors (VIII or IX) they are more susceptible to contamination by infectious agents present in the blood from which the transfused elements come. In the past, blood banks did not usually perform HIV detection tests and many hemophilic patients have become infected with the virus.
25. What are anticoagulants? What are the practical applications of anticoagulants, such as heparin, in Medicine?
  • Anticoagulants are substances that block clotting reactions and therefore stop the coagulation process. 
  • Ordinarily, anticoagulants circulate in the plasma, since under normal conditions blood must be maintained fluid. 
  • In Medicine, anticoagulants such as heparin are used in surgeries in which tissue injuries caused by surgery act could trigger undesirable systemic blood clotting. 
  • They are also used to avoid the formation of thrombi inside the blood vessels of patients riskat an increased risk for thrombosis.
26. What is dicoumarol? What is the role of this substance in the clotting process and what are some examples of its toxicity?
  • Dicoumarol is an anticoagulant drug. Due to its molecular structure, dicoumarol competes with vitamin K to bind to substrates, thus blocking the formation of clotting factors and interrupting the production of prothrombin. 
  • Dicoumarol is found in some decomposing vegetables and can cause severe internal hemorrhages when those vegetables are accidentally ingested. 
  • Coumarinic anticoagulants cannot be administered during pregnancy since they pass the placental barrier and can cause fetal hemorrhages.
27. Streptokinase is a substance used in the treatment of acute myocardial infarction. What is function of this substance?
  • Substances known as fibrinolytics, such as streptokinase and urokinase, can destroy thrombi (clots formed inside blood vessels, capillaries or within the chambers of the heart) and are used in the treatment of obstructions of the coronary arteries or other blood vessels. 
  • Streptokinase destroys the fibrin network and as a result dissolves the thrombotic clot. Its name is derived from the bacteria that produce it, streptococci.

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