...IGCSE HUMAN BIOLOGY Chapter Questions – Section 8 1) Explain the meaning of the following terms: a) Homeostasis Homeostasis is the name given to all the processes, which operate to maintain a stable internal environment within the body. This means that the body works constantly to prevent large fluctuations in temperature, blood sugar levels, water content of blood, acidity of the blood, amount of oxygen and carbon dioxide within the blood, the level of hormones in the blood, the heart rate and the activity of pathogens. b) Excretion Excretion means the removal of waste products that have resulted from chemical (metabolic) reactions within the body. c) Ultrafiltration Ultrafiltration is the process of separating the blood into molecules of different sizes under pressure in the kidneys. d) Selective Re-absorption This is the re-absorption of various substances in different amounts in the kidney tubule. e) Endotherm Humans are endotherms, which means that they generate heat from inside. Endotherms use heat from chemical reactions in its cells to warm its body. 2) The diagram shows a simple diagram of the kidney tubule (nephron). a) What are the parts labelled X, Y and Z? X – Glomerulus Y – Bowman’s capsule Z – Loop of Henle b) Four places in the nephron and its blood supply are labelled A, B, C and D. Which of the four substances are found at each of these four...
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...ORGAN FOR SALT AND WATER BALANCE AND EXCRETION SALT AND WATER BALANCE AND THE ENVIRONMENT OSMOCONFORMERS – Animals that match their body osmolarity to their environment actively or passively. OSMOREGULATORS – Animals, however, tend to maintain a constant concentration in their internal fluids different from that of their environment. EXCRETION OF NITROGENOUS WASTE Nitrogenous waste is mostly in the form of ammonia, which is highly soluble in water, and is excreted by diffusion from the blood across the gill membranes. AMMONOTELIC – Animals that eliminate nitrogenous waste as ammonia. Includes aquatic invertebrates, bony fishes, crocodiles, and amphibian tadpoles. UREOTELIC – Excrete urea as their major nitrogenous waste. Among these animals are mammals, amphibians, and cartilaginous fishes. Urea is soluble in water but its excretion at low concentrations needs a large volume of water. URICOTELIC – Includes insects, reptiles, birds, and some amphibians. These animals use very little water to dispose their nitrogenous waste. Uric acid is insoluble in water and is excreted in semisolid form. EXCRETORY SYSTEM FLAME CELLS – A hollow cell in the excretory system of certain invertebrates, including flatworms containing a tuft of cilia inside a tubule. METANEPHRIDIA – Filtration process of body fluids and processing of urine. MALPHIGIAN TUBULES – Blind tubes hanging into the body cavity and connected to the gut. GREEN GLAND – Made up of an end sac...
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...Lung cancer arises from the epithelial of the respiratory track. Lung cancer is the most severe cancer compare to the other cases of cancer. Lung cancer is the number one killer in United States and the world. In this country alone, there are 219440 new cases yearly and 159390 death yearly which is almost 57% of death yearly form lung cancer. These cases of lung cancer account for 14% of all cancer in men and 15% in women every year. (McCance, Huether, Brashers, & Rote, 2010, p. 1299). Although tobacco smoking is the number causes of lung cancer, there are some new cases of lung cancer arising every year without any cause. Cigarette smoking accounts for almost 90% of all lung cancer (http://www.cdc.gov/cancer/lung/basic_info/index.htm) . Other causes of lung cancer can include radon, asbestos, second hand smoking, family history, diet and air pollution. Lung cancer arises from a single changed epithelial cell in the tracheobronchial airways. A carcinogen from cigarette smoke or other predisposing factor like inherited gene bind to a cell DNA and damages it thereby resulting in multiple genetic abnormalities in bronchial cell which include deletion of chromosomes, activation of oncogenes and inactivation of tumor suppressing genes. This damage results in cellular changes, abnormal cell growth and eventually a malignant cell. The DNA undergoes further changes and becomes unstable as the DNA is passed to daughter’s cell. With the accumulation of genetic changes, the pulmonary epithelium...
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...6. Blood Gases and Acid-Base Balance Introduction Under normal conditions, physiologic and metabolic processes in the human body require specific and constant conditions for relevant reactions or mechanisms to occur. One of the most important factors that influence reactions and/or metabolic processes is the pH for the system or environment. The end product of most of the metabolic processes of carbohydrates, lipids and proteins is the production of acids ( organic acids, volatile acids and fixed acids). These acids if not neutralized would influence the physiologic pH of blood and tissues of the body. Therefore, a buffer system must be available to prevent the accumulation of these acids and to inhibit their harmful effects. This chapter describes the mechanism and action of buffers in maintaining the proper pH in health and in disease states. Definitions (Review of basic concepts) 1. Acids: Compounds that release hydrogen (proton donors) 2. Bases: Compounds that accepts hydrogen (proton acceptor) 3. Strong Acids: Compounds with weak affinity to H+ (release all H+ ions) 4. Strong Base: Compounds with strong affinity to H+ (Bind H+ ions) 5. The dissociation constant K: It reflects the strength of an acid or base. The larger the K value, the greater the dissociation of H+ ions, thus the stronger the acid. 6. pK: is the negative log of K. The smaller the pK the stronger the acid (Strong acids has a pK 9.0) 7. Buffers: A combination of weak acid and...
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...December The 21ST. Feeding: Is the capacity LO have to take solid food (as animals do), digest it first and absorb it later (like Fungi do) or built up for themselves -Photosynthesis- (like plants do). (p. 293) Breathing: Is the capacity LO have to take in oxygen and give out carbon dioxide. The Exchange of Gases: Locomotion: Is the capacity most single-celled creatures and animals have to move about as a whole. Fungi and Plants, move with some parts of their bodies. Respiration: (Glucose + 6O2 + 6H2O + Energy) Breaking down process. Is the capacity LO have to break-down food to obtain energy. Most need oxygen. (p. 19) Excretion: Breaking down process. Is the capacity LO have to respire and other chemical changes in the cells that produce waste products such as Carbon Dioxide. Irritability: Irritability is an excessive response to stimuli. The term is used for both the physiological reaction to stimuli and for the pathological, abnormal or excessive sensitivity to stimuli; it is usually used to refer to anger or frustration. Adaptability: Is a necessary skill for leaders to develop in order to respond effectively to this change. Growing: Is the capacity Bacteria and Single-celled creatures have to increase in size. Many-celled organism increase the numbers of cells in their bodies change their body shape and size. (p. 306) Reproduction: Is the...
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...9.4 Water Balance The body’s internal environment of extracellular fluid must maintain a constant volume, solute content, and often temperature. Humans and other organisms require a stable aqueous environment to survive. They carry this aqueous environment inside their body, and they must continuously replenish and maintain it. Aquatic organisms must also maintain their internal environment, since the conditions of the external environment change in terms of solutes and temperature. Atlantic salmon spends part of its life cycle in both freshwater and saltwater environments. For the first few years of its life, the salmon lives in freshwater rivers and lakes, where the solute concentration is less than the concentration within its body. This concentration gradient results in the uptake of water into the salmon’s internal environment, and therefore homeostatic mechanisms must expel the excess water from the body. As the salmon matures, it abandons the freshwater environment for the salt water of the Atlantic Ocean, where the concentration of solutes is higher. In this saltwater environment, the salmon experiences a continuous loss of water from its body, which it must replenish. Because water is not as abundant on land as it is in aquatic environments, terrestrial organisms require mechanisms to conserve water and maintain a homeostatic balance of solutes within their body. OSMOSIS – define the following: During osmosis, water molecules move from a region where they are highly...
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...capsule. Excretory systems regulate solute movement between internal fluids and the external environment. The kidney, the excretory organs of vertebrates is the mammal’s principal organ of excretion and osmoregulation. Osmoregulation regulates solute concentrations and balances the gain and loss of water. Thus, regulation of the osmotic concentrations of blood plasma by the kidneys ensures the osmotic regulation of all other body fluids. Excretion gets rid of many toxic metabolic waste products, particularly the nitrogenous compound urea. The mammalian excretory system centers on paired kidneys, which are also the principal site of water balance and salt regulation. Nephron is the functional unit of the vertebrate kidney approximately one million of nephrons can found in human kidney. Nephrons perform the function osmoregulation and excretion by filtration, reabsorption, secretion and excretion. Pressure-filtering of body fluids involve only filtration of most small molecules from blood plasma to form an ultrafiltrate of plasma. Selectively reabsorption by reclaiming valuable solutes like most of the water and other molecules from the ultrafiltrate and leaving behind waste material will be excreted. Secretion of hydrogen ion into the urine helps to maintain the acid-base balance. Excretion is to remove the metabolic waste products and unwanted chemicals or substances into the filtrate. Approximately 99% of the glomerular filtrate is reabsorbed into the system in the nephron and...
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...Characteristics of Living Organisms In order to identify living organisms, scientists listed 7 characteristics which all living organisms have: 1. Nutrition: Taking in nutrients which are organic substances and mineral ions, containing raw materials and energy for growth and tissue repair, absorbing and assimilating them. 2. Excretion: Removal from organisms of toxic materials, the waste products of metabolism and substances in excess. 3. Respiration: Chemical reactions that break down nutrient molecules in living cells to release energy. 4. Sensitivity: The ability to detect or sense changes in the environment and to make responses. 5. Reproduction: Progresses that make more of the same kind of organism. 6. Growth: The permanent increase in size and dry mass by an increase in number of cells, cell size, or both. 7. Movement: An action by an organism or part of an organism that changes position or place. The seven characteristics could be memorized by the term “Mrs. Gren”. Definitions: Metabolism: Chemical reactions taking place in cells. Stimuli: Changes in the environment which organisms response to. Characteristics of living things There are seven activities which make organisms different from non-living things. These are the seven characteristics of living organisms. 1. Nutrition Living things take in materials from their surroundings that they use for growth or to provide energy. Nutrition is the process by which organisms...
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...Pharmacokinetics Pharmacokinetics is a branch of pharmacology which studies what happens when foreign substances enter the human body. It looks at what happens to the substances when they are administered, up until the point at which they are excreted. In humans, the substances that are normally studied are hormones, toxins or other pharmaceutical agents such as paracetamol or aspirin. The knowledge of Pharmacokinetics is used to come up with an effective plan on how to administer drugs to patients. Some of the main goals of pharmacokinetics are to enhance the efficiency and reduce the toxicity of drugs. Pharmacokinetics comprises of 5 pathways, these are: Administration, adsorption, distribution, metabolism and elimination. Administration in pharmacokinetics is studying how the drug is going to be delivered into the body. A few methods include: Oral, Skin, lungs, eyes, and ears. For a drug to reach the target cells, it must be able to move across membranes and enter the blood stream via adsorption. If the drug has poor solubility or has an inability to pass through cell membranes, then this can affect how well the drugs intended effects work. The membranes that separate tissues from blood capillary’s are composed of lipids, this means that lipid soluble drugs will readily cross these membranes, whereas ionised drugs will not. Absorption also links into drug administration, as if a drug that was taken orally did not get adsorbed properly by the body, then it signals the means...
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...water only the descending part is and the water is lost through osmosis. The distal convoluted tubule has similarity to the proximal convoluted tubule as both secretion and reabsorption occurs in both places. Once the fluid has left the loop of Henle it travels to the distal tubule. Electrolytes and pH of the fluid is adjusted for homeostasis. Water is reabsorbed into the blood capillaries by osmosis and passive transport is used for potassium and sodium reabsorption. The final stage in the nephron is the collecting duct. The body can control the level of dilation and absorption in each collecting duct. Salts can be retained to maintain electrolyte balance which happens in the collecting ducts. Final reabsorption can take place before excretion but the collecting ducts are largely impermeable to water without the presence of antidiuretic hormone (ADH)....
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...Taking a tablet orally is one of the most commonly used way to administer medication. No one ever thinks about what happens to the medication taken after it’s inside the body. Any tablet you may take or any other forms of administration goes through a process that all drugs must go through, this is called the drug cycle. There are four main steps in the drug cycle and they are; Absorption, Distribution, Metabolism, and Excretion. Most drugs follow the drug cycle but when taking medication orally in can change the order. Absorption is the first Step in the drug cycle, this is where the drug goes from the site of administration into the blood stream. After a tablet is taken the first thing that happens to it is it disintegrates so that just the drug itself is left. The drug is then dissolved in body fluids such as saliva and gastric juice. From there it is then absorbed into blood vessels. Whether or not you have food in your stomach can change the rate of absorption. In other words if you have a full stomach it may take longger for the drug to absorb opposed to having an empty stomach....
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...calcium metabolism, not including vitamin D. When blood plasma calcium is high, the parafollicular cells of the thyroid gland releases calcitonin (DeLuca, 2014). When there is a calcium surplus in the blood, calcitonin is released to inhibit the resorption of calcium from the bone. Calcium is able to be deposited into the bones while removal of calcium from the bones is inhibited. When there is an increase in calcium ion excretion from the kidneys, there is inhibition of phosphate ion excretion in the urine. The phosphate ions in the plasma forms insoluble salts with the calcium ions, this causes bladder stones to form (Harcourt-Brown, 1996). There is also a decrease of calcitriol formation which inhibits calcium absorption of small intestine epithelial cells to prevent continual increase in blood calcium (DeLuca, 2014). The excess calcitriol is converted to calcitroic acid and excreted in bile salts. When blood serum calcium is low, PTH is is released from the parathyroid gland. This causes a decrease in calcium ion excretion and an increase in phosphate ion excretion in the urine. High levels of PTH also activate calbindin, a calcium transporter found in the small intestine, and it activates 1α-hydroxylase in the kidneys, encouraging the synthesis calcitriol (Crenshaw et al., 2014). Role of PTH and Hypoparathyroidism When calcium levels in the blood are low, parathyroid gland releases PTH. This hormone increases renal reabsorption of calcium and decreases reabsorption of phosphate...
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...HIGH INTAKE OF DIETARY PROTEIN HAS NO ADVERSE EFFECTS ON BONES HEALTH Pearl Pullman NDFS 200 – Fall 2013 October 08, 2013 ABSTRACT Recently, the effects of high protein diets on bone structure have been controversial, with evidence suggesting negative and positive affects on bone. The objective of this paper is to discover how a high intake of dietary protein affects bones. In one study, subjects consumed a high protein and high dairy (HPHD) diet, an adequate protein and medium dairy (APMD), or an adequate protein and low dairy diet (APLD). The researchers collected blood and urine samples from the subjects. Subjects consuming HPHD diets showed adequate bone health after 16-weeks of monitored exercise evidence. In another study, researchers measured the plasma concentrations of insulin-like growth factor 1 (IGF-1). IGF-1 plays an important role in proper skeletal growth and development. Subjects consuming 42 g protein compared to the group consuming 70 g carbohydrate had an increase in plasma IGF-1 (P = 0.01). In another study, researchers measured calcium absorption by collecting blood and urine samples to assess the effects of the diet on biomarkers of bone metabolism. In this 15-week study, researchers discovered that a diet with high protein increased the absorption of dietary calcium and IGF-I by >20% compared to the low protein diet. In another study, participants were given either a 30g whey protein drink or a placebo of 2.1g protein drink over a 2-year...
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...AC 1.1 By Life Processes common to living organisms Laura Judges TABLE OF CONTENTS Chapter 1 page Introduction to life processes 2 Chapter 2 page Movement 2-3 Chapter 3 page Repoduction 3 Chapter 4 page Sensitivity 3-4 Chapter 5 page Growth 4 Chapter 6 page Respiration 5 Chapter 7 page Excretion 5-6 Chapter 8 page Nutrition 6-7 Chapter 9 page Conclusion 7-8 Chapter 10 page Bibilography 9 Introduction to life processes The most basic of living things consist of just one single cell for example bacteria, while more complex organisms such as humans are multi-cellular. An organism is defined as an individual animal, plant or single-celled life form. Therefore the cell is considered the smallest unit of life competent of a self-sufficient existence. There are seven things that all living organisms from bacteria to plants to animals all have in common and whether something is living or not is usually compared to the seven life processes. These processes are movement, reproduction, sensitivity, growth, respiration, excretion and nutrition. The acronym ‘MRS GREN’ will be used when discussing the processes of life movement All living things move to some kind of degree and this is the most apparent within the animal kingdom. Animals are able to physically move themselves from one place to another; humans will usually use their muscles in order to be able to move where as other animals may have to hop, crawl, swim or fly. Movement is very important for gathering sustenance...
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...salt excretion takes place in both the gills and the lumen of the Grindylows. A Na+/K+/2Cl- co-transporter brings Cl- and K+ into the cell using Na+ electrochemical gradient. Cl- then exits through the apical membrane via an anion channel by its electrochemical gradient, created by the Na+/K+ ATPase, into the lumen or the external water. At the same time K+ leaves through the basolateral K+ channel. The Na+ that enters the cell with K+/Cl- leaves in exchange for K+ via the Na+/K+ ATPase. As the Cl- is sent outside the cell it creates a small electrical potential between extra cellular fluid and seawater. The potential difference drives the outward movement of Na+ between the cells thus excreting the salt in the body. The glomerulus of the kidney reabsorbs macromolecules such as...
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