2 Topic Outline Hormonal Control Digestion Absorption of Digested Foods Functions of the LiverThe Transport SystemGas ExchangeHOMEMAIN PAGE
3 Option H.1 Hormonal Control H.1.1 State that hormones are chemical messengers secreted by endocrine glands into the blood and transported by the blood to specific target cells.Hormones are chemical messengers secreted by endocrine glands into the blood and transported by blood to specific target cells.MAIN PAGE
4 H.1.2 State that hormones can be steroids, peptides and tyrosine derivatives and provideone example of each.Hormones can be steroids, peptides andtyrosine derivatives and provide one example of each.
5 H.1.3 Distinguish between the mode of action of steroid hormones and peptide hormones.Steroids enter cells and affect genes directly. Peptides bindto receptors in the membrane which causes therelease of a secondary messenger inside the cell
6 hypothalamus and the pituitary gland. H.1.4 Draw a diagram of thehypothalamus and the pituitary gland.Drawing will be inserted at a later date.
7 H.1.5 Explain the control of thyroxin secretion by negative feedback.The release of thyroxin is regulated by the pituitarygland and the hypothalamus. The hypothalamus controlsthe pituitary's secretion of tropic hormones, and these,in turn, stimulate the secretion of hormones fromthe thyroid, adrenal cortex, and gonads (the testes or ovaries).
8 As the concentration of the hormones produced by these target glands rises in the blood, the hypothalamusdecreases its production of releasing hormones, thepituitary decreases its hormone production, andproduction of thyroxin by the target gland also slows.By way of the hypothalamus, which receives informationfrom many other parts of the brain, hormone productionis also regulated in response to other changesin the external and internal environments.
9 H.1.6 Explain the control of ADH secretion by negative feedback. One important homeostatic function of the body is keepingthe blood volume constant. This is accomplished byregulation of the rate at which water is removed fromthe bloodstream by the kidneys.
10 A hormone called ADH (anti-diuretic hormone) is produced by the hypothalamus and released from the pituitary glandacts on the kidney's tubules to decrease water excretion. Theproduction of ADH is controlled by sensory receptors inthe circulatory system, particularly in the heart, thatmeasures blood pressure- an indirectmeasure of blood volume.
11 When blood pressure goes up, firing of these receptors inhibits the release of ADH, and more water is excreted,reducing blood volume. As blood pressure goes down,the stimulus from the receptors decreases, ADHproduction increases, water is retained by the kidney,and blood pressure and volume increase.
12 Option H.2 DigestionH.2.1 State that digestive juices are secreted into the alimentary canal by glands including salivary, stomach wall, pancreas and wall of small intestine.Digestive juices are secreted into the alimentary canal by glands including salivary, stomach wall, pancreas and wall of small intestine.MAIN PAGE
13 H.2.2 Draw the structural features of exocrine glands including secretory cells grouped into acini and ducts.Drawing will be inserted at a later date.
14 H.2.2 Draw the structural features of exocrine glands including secretory cells grouped into acini and ducts.Drawing will be inserted at a later date.
15 H.2.3 Explain the structural features of exocrine gland cells as seen in electron micrographs.A group of cells surround an empty space (acini).Hormones from cells tickle into acini and thento the duct. The hormones are then transportedto the destination (duodenum, skin, etc). In shortthe alignment of exocrine cells around an aciniincrease surface area for hormone secretion.
16 H.2.4 State the contents of saliva, gastric juice and pancreatic juice.Saliva is made of water and amylase. The contents ofgastric juice is HCl, pepsin and mucus. Pancreatic juiceis made of trypsin, chymotrypsin, nuclease,pancreatic amylase, lipase, and sodium bicarbonate.
17 H.2.5 Outline the control of digestive juice secretion by nerves and hormones.
18 H.2.6 Outline the role of membrane-bound enzymes in the surface cells of the small intestine incompleting digestion.Some digestive enzymes are immobilized in thesurface membrane of cells on the surface of intestinal villi. These enzymes continue working even if the cellis rubbed off the villus and mixed intothe intestinal contents.
19 H.2.7 Explain why cellulose remains undigested in the human alimentary canal.Humans have no enzymes to break downthe beta linkages in cellulose.
20 H.2.8 Explain why pepsin and trypsin are initially synthesized as inactive precursors and how they are subsequently activated.They stay active first so that they don't digest your own cells. HCl activates pepsin and makes it more acidic. A basic molecule changes the pH of trypsinogen. Thus trypsin becomes basic.
21 endopeptidases and exopeptidases. H.2.9 Outline the action ofendopeptidases and exopeptidases.
22 H2.10 Explain the problem of lipid digestion in a hydrophilic medium and the role ofbile in overcoming this problem.Lipids tend to coalesce (lump together) and are onlyaccessible to lipase at the lipid-water interface. Bilebreaks the lumps down and thus acts as an emulsifier.Thus the surface area for lipase to digest the lipids increases.
23 Option H.3 Absorption of Digested Foods H.3.1 Draw a portion of the ileum (in transverse section) as seen under a light microscope.Drawing will be inserted at a later dateMAIN PAGE
24 H.3.2 Explain the structural features of an epithelium cell of a villus as seen in electron micrographs includingmicrovilli, mitochondria, pinocytotic vesiclesand tight junctions.Epithelium cells of villi contain many mitochdondria.These mitochondria produce a lot of energy, which isnecessary for absorption. Microvilli on the epithelial cellsthat line the villi increase surface area for absorption.Pinocytotic vesicles take fatty acds, glycerol, aminoacids and glucose from the intestines throughthe villi to blood vessels.
25 Some molecules diffuse across the villi, while others are carried. The epithelium cells are physically connected,so nothing can squeeze between them. Moreover, tightjunctions separate the proteins of the lumen side fromthe blood side, so proteins cannot move and allowmolevules to diffuse back to the wrong side. Thusthe contents of the intestine are kept separatefrom the body fluids on the opposite side.
26 H.3.3 Explain the mechanisms used by the ileum to absorb and transport food, including facilitateddiffusion, active transport and endocytosis.Water and small molecules are pumped or carriedacross the membrane by transport proteins throughfacilitated diffusion or activated transport. Largermolecules such as proteins and polysaccharidesenter by endocytosis.
27 In endocytosis the cell takes in macromolecules by forming vesicles derived from the plasma membrane.In facilitated diffusion, little protein channels facilitateddiffusion but no energy is used. In active transport, thesodium-potassium pump pumps moleculesin and out while using energy.
28 H.3.4 List the materials that are not absorbed and are egested.Cellulose, lignin (protein found in wood), bilepigments, bacteria (because they have specialcell walls), and intestinal cells.
29 Option H.4 Functions of the Liver H.4.1 Outline the circulation of blood through liver tissue including the hepatic artery, hepatic portal vein, sinusoids and hepatic vein.Blood in the hepatic artery comes from the heart and full of oxygen, but it has little nutrients. On the other hand, the hepatic portal vein comes from the small intestines and is rich in nutrients (also could contain poisons, alcohol) although it lacks oxygen.MAIN PAGE
30 The hepatic artery and hepatic portal vein flow together in the liver and mix their contents. The sinusoids, whichare highly permeable capillaries and which containKupffer's cells, absorb all the nutrients. Finally, thesinusoids expel these nutrients through thehepatic vein into the body when necessary.
31 H.4.2 Explain the need for the liver to regulate levels of nutrients in the blood.Because the body may not need all the eaten nutrientsat once, the liver needs to regulate the levels of nutrients.It stores glucose in the form of glycogen, so it regulatesnutrients by balancing glucose levels in the blood. Theliver also breaks down fats and deaminates amino acidswhere there is no glycogen left.
32 H.4.3 Outline the role of the liver in the storage of nutrients including carbohydrate, iron,retinol and calciferol.The liver stores carbohydrates as glycogen for energyreserve. It also stores iron from broken down hemoglobinand the vitamins retinol (vitamin A - for night vision)and calciferol (vitamin D - so body can use calcium).
33 H.4.4 Describe the process of bile secretion. In the liver, as Kupffer's cells break down blood cells,blood pigments that get separated from hemoglobinare dumped into the canaliculi as bile. The canaliculiflow into the bile duct and into the gall bladder.The gallbladder stores the bile until it isneeded in the duodenum.
34 The contents of bile include bicarbonates, bile salts (digestion and absorption of fats) and bile pigments(by products of red blood cell destruction). When foodenters the duedenum enters the duodenum, thesphincter oddi relaxes and allows bile to besecreted into the small intestine.
35 H.4.5 Describe the process of erythrocyte and hemoglobin breakdown in the liverincluding phagocytosis, digestion ofglobin and bile pigment formation.Erythrocytes (red blood cells), after about 4 months,are destroyed by Kupffer's cells (phagocytic) in the liver.Hemoglobin is converted to a yellow pigment (bilirubin),the iron is stored and proteins (globin) are brokeindown into amino acids. Bilirubin is transferred tothe bile duct, released into the intestines and convertedby bacteria to a yellow pigment which gives thecharacteristic color of feces.
36 H4.6 State that the liver synthesizes plasma proteins and cholesterol.The liver synthesizes plasma proteinsand cholesterol.
37 Option H.5 The Transport System H.5.1 Explain the events of the cardiac cycle including atrial and ventricular systole and diastole, and heart sounds.The cardiac muscle does not get a nerve message from the nervous system to initiate its activity,instead it has a special type of tissue that spontaneously generates electric activity. In the wall of the right atrium there is a group ofcells that forms a special tissue calledthe sino-atrial node.MAIN PAGE
38 In the wall between the right atrium and the right ventricle there is another similar tissue called the atrioventricularnode (AVN). The sino atrial node (SAN), is also knownas the pacemaker. It generates rhythmic electric wavesthat spread to the two atria causing them to contract.The electric wave spreading from the SAN reaches theAVN and it causes it to fire an electric wavethat spreads to the two ventricles.
39 The electric wave from the AVN travels in special muscle fibres called the bundle of His and from there throughthe pukinje fibers to the two ventricles. This makesthe two ventricles contract.
40 H.5.2 Analyse data showing pressure and volume changes in the left atrium, left ventricleand the aorta during the cardiac cycle.The highest blood pressure pressure is owned by the aorta.This is because it receives blood from the left ventricle,which contracts with the biggest force pushing theblood into the aorta with a big force andresulting in high blood pressure.
41 Away from the aorta, pressure starts to decrease because it's further away from th left ventricle whichis the pump that pushes the blood into the arteries.Thus, the pressure dampens as the blood ventriclethrough the vena cava it has the lowest blood pressure.
42 H.5.3 Outline the mechanisms that control the heartbeat including the SA (sinoatrial) node,AV (atrioventricular) node and conductingfibres in the ventricular walls.SA node sends the signal across the atria for itcontract. AV node sends a signal to ventricles thatsweeps down through the septum of the heart toand to sides of the ventricles. This causes the ventricleto contract from the bottom up. Conducting fibers inthe ventricular walls send a signal down the septum.
43 H.5.4 Outline atherosclerosis and the causes of coronary thrombosis.Artiosclerosis - if a person eats a diet high in saturatedfats, plaques (deposits of lipids such as cholesterol)develop on the inner walls of the arteries, narrowingthe lumen. Thus the transport system becomes moreinefficient as less blood volume can be pumped throughcoronary thrombosis - the plaques can loosen and startto travel blocking smaller arteries. If such a block occursin the heart or brain, a heart attack or a stroke occurs.
44 H.5.5 Discuss the factors which affect the occurance of coronary heart disease.Risk factors include: having parents with heartattacks (genetic), old age (body wears down),being male, smoking, obesity, eating too muchsaturated fat and cholesterol (clog arteries),lack of exercise (can't get rid of fatty acids).
45 H.5.6 Outline how tissue fluid and lymph are formed in body tissues.Hydrostatic pressure causes fluid (H2O and smallsolutes such as sugar, salt, and O2) to leak out ofcapillaries (single celled). Blood cells and proteinsdissolved in the blood are too large to passthrough and remain in the capillaries
46 About 85% of the fluid that leaves the blood at the arterial end of a capillary bed reenters fromthe interstitial fluid at the venous end due toosmotic pressure. The rest is eventually returnedto blood vessels by the lymphatic system. Thelost fluid and occasional proteins thus returnto blood via the lymph system. Fluid enters thelymph system by diffusing into lymph capillariesintermingled among capillaries of cardiovascularsystem. The lymph contains the blood fluid, lipids(from small intestine) and WBC's (at lymph nodes).
47 H.5.7 Outline the transport functions of the lymphatic system.
48 H.6.1 Define partial pressure. Option H.6 Gas ExchangeH.6.1 Define partial pressure.Partial pressure is the pressure exerted by each component in a mixture. The pressure of a gas in a mixture is the same as it would exert if it occupied the same volume alone at the same temperature.MAIN PAGE
49 H.6.2 Explain the oxygen dissociation curves of adult and fetal hemoglobin and myoglobin.The oxygen dissociation curve of adult hemoglobinis to the right of the oxygen dissociation curve offetal hemoglobin. In other words, adult O2 saturationof hemoglobin is always lower than fetal O2 saturationof hemoglobin at the same O2 partial pressure.
50 This is because fetuses don't have their own O2 source, so they must have high levels of O2 in hemoglobin forreserve. When the O2 partial pressure is low, O2diffuses out of hemoglobin very fast, so cells thatare low on O2 can quickly receive muchO2 (since they need it the most).
51 The oxygen-storing protein myoglobin has a large reserve of O2 in case O2 concentrations get really low(e.g., sprinting). When this occurs, myoglobin veryquickly releases its O2 to supportthe oxygen-depleted cells.
52 H.6.3 Describe how carbon dioxide is carried by the blood including the action of carbonic anhydrase,the chloride shift and buffering by plasma proteins.Carbon dioxide produced by body tissues diffuses intothe interstitial fluid and into the plasma. Less than10% remains in the plasma as dissolved CO2. Therest (70%) diffuses into red blood cells, where some(20%) is picked up and transported by hemoglobin.
53 Most of the CO2 reacts with H20 in the red blood cells to form carbonic acid. Red blood cells contain the enzymecarbonic anhydrase, which catalyzes this reaction. Carbonicacid dissociates into a bicarbonate ion and hydrogen ion(H+). Hemoglobin (a plasma protein) binds most of theH+, preventing them from acidifying the blood.
54 The reversibility of the carbonic acid- bicarbonate conversion also helps buffer the blood, releasingor removing H+ depending on the pH. Chlorinegoes into the red blood cells when bicarbonatecomes out. This is referred to as the chloride shift.
55 H.6.4 Explain the role of the Bohr shift in the supply of oxygen to respiring tissues.The Bohr shift helps the body releasemore O2 to respiring tissues when the pH is moreacidic. During exercise, a lot of CO2 is produced,which results in larger amounts of hydrogen ionsthat acidify the blood. Thus, the Bohr shift letsthe body know it's exercising.
56 H.6.5 Explain how and why ventilation rate varies with exercise.During inhalation, the intercostal muscles and thediaphragm contract. The volume of the lungs increasesas the diaphragm moves down and the rib cage expands.Air pressure in the lungs falls below that of the atmosphereand air rushes into the lungs. Exhalation occurs whenthe rib muscles and diaphragm relax, restoring thethoracic cavity to its smaller volume.
57 Thus pressure becomes greater in lungs than in the atmosphere and air rushes out. Action of the intercostalmuscles in increasing lung volume is most important duringvigorous exercise. Increase in lung volume during shallowinhalation results from the action of the diaphragm.
58 H.6.6 Outline the possible causes of lung cancer and asthma and their effects on the gas exchange system.Smoking and inhaling other carcinogens (e.g., pollutedareas, coal) may cause lung cancer. The effect oflung cancer is that large cancerous cells in lungs reducetheir surface area. Reaction to exercise and stress maycause asthma. The effect of asthma is that lung tissuesswell, so they constrict the area of O2 absorption. Bothlung cancer and asthma result in efficient gas exchange.
59 H.6.7 Explain the problem of gas exchange at high altitudes and the way the body acclimatizes.Mountain sickness may occur when a person travelsquickly from a low to high altitude. Over a period oftime the person becomes acclimatized: red blood cellproduction and ventilation rate increase. People livingpermanently at high altitude have greater lung surfacearea and larger vital capacity than those living at sea level.MAIN PAGE