Role of Bone Cells in Homeostasis of Blood Calcium Ion Concentration
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This article discusses how bone cells respond to hormones involved in the homeostasis of blood calcium ion concentration. It explains the role of parathyroid hormone (PTH) and calcitonin in regulating calcium levels and balancing blood calcium ion concentrations.
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Name: Student number: BIOL121 WORKSHEET Due:3am Wednesday 8thMay Submit:via Turnitin link on BIOL121 LEO page Weighting:20% final grade Answers must be in an easy to read colour that is distinctly different to black. QUESTION 1 Which type of immunity is expressed in the following scenarios? Choose between: ο·Non-specific (first line defence) ο·Specific (antibody-mediated) ο·Specific (cell-mediated immunity)(0.5 mark each β total 2 marks) ScenarioType of immunity Bacterial septicaemia (bacterial contamination in systemic circulation) Specific (antibody mediated) The pH of hydrochloric acid in the stomach acts to destroy ingested bacteria Non-specific (first-line defence) A liver cell mutates and becomes cancerous Specific (Cell-mediated immunity) A virus multiplies inside the epithelial cells in your throat. Non-specific (first-line defence)
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QUESTION2 ChooseTWOof the below scenarios and highlight these rowsbold. State which general property of adaptive immunity the scenario illustrates in the second column. Select ONE phrase (from the list below) that BEST describes what is happening at a cellular level to result in this property of adaptive immunity. Write the letter corresponding to this phrase in the third column. An example is included. (2 mark) ScenarioGeneral property of immunity Explanation Even though your body contains a relatively small number of lymphocytes, your immune system can mount a response against almost any antigen it encounters. VersatilityA Generally, after an initial infection, subsequent immune responses to that antigen are faster, stronger and more sustained. MemoryC You can suffer from βthe fluβ multiple times throughout your lifetime. Your immune system can distinguish between antigens on your own cells, and those of an invading pathogen. Self- recognitionG Possible phrases are listed below. Not all phrases will need to be used and only ONE phrase is required per row. If you record more than one, you will not be awarded any marks for your explanation. AThere are millions of different lymphocyte populations, each of which is sensitive to a different antigen. Lymphocytes proliferate when activated by their specific antigen. BEach T or B cell has receptors that respond to only one antigen and ignores all others. CActivated lymphocytes produce two groups of cells: one group that attacks the invader immediately, and another that remains inactive unless it is exposed to the same antigen at a later date. DEach T and B cell can recognise many antigens and respond to a wide variety of possible threats. ET cells are versatile because they produce copious quantities of antibodies that can respond to a wide variety of threats. FPhagocytes have a reduced ability to destroy pathogens during subsequent infections. GThe immune response ignores self-antigens and targets non-self-antigens. HB cells differentiate into T cells to create a long-lived immune response. 2
QUESTION 3 Describe how bone cells respond to the hormones involved in the homeostasis of blood calcium ion concentration.(3 marks) Bone cells are crucial in homeostasis of blood calcium. Parathyroid glands release parathyroid hormone (PTH) when there are low blood calcium levels, which stimulates bone resorption. Besides, PTH directly affects the kidneys by preventing the loss of calcium ions through urine; hence reabsorption of the ions. On the other hand, thyroid glands release calcitonin in response to high blood calcium. Calcitonin suppresses bone resorption activity and increases the amount of calcium excreted in urine. PTH and calcitonin act as feedback mechanisms to balance blood calcium ion concentrations(Chonchol & Kendrick, 2019). QUESTION 4 Why is injury to the medulla oblongata usually fatal?(2 marks) Medulla oblongata is found on brain stem. It is essential in regulating the bodyβs involuntary processes, such as respiration, digestion, reflex, and neuronal responses. An injury to this part is life-threatening as it may disrupt the involuntary processes. It may cause paralysis, loss of body coordination, loss touch senses, and ultimately cause death. QUESTION 5 Complete the following table summarising the effects of autonomic innervation on target tissues. You must include both the effect upon the target tissue and a consequence of this stimulation in your answer. The first row has been completed as an example. (1 mark/box; 4 marks total) Target tissueEffect of sympathetic stimulationEffect of parasympathetic stimulation Contractile force of the Contractile force increases; more blood pumped from heart No parasympathetic innervation of ventricular myocardium; therefore, no 3
heartresult Airways in the lungs Smooth muscles relax; bronchioles increase in diameter; results in dilation of the bronchioles Smooth muscles contract; bronchioles decrease in diameter; hence causing constriction of the bronchioles PupilRadial muscles contract; the pupil dilatesCircular muscles contract; thus, the pupil constricts QUESTION6 Using the diagram provided as a prompt, outline the four steps involved in the transmission of an electrical impulse from the presynaptic neurone to the post synaptic neurone.(4 marks) StepOutline 1 Nerve impulse at the axon end stimulates the opening of the Na+voltage-gated channel. Na+depolarizes the pre-synaptic membrane, and activates the K+channel, which further depolarizes voltage gated Ca+channel(Pereda, 2014). 2 Calcium ions results in the fusion of synaptic vesicles with the pre-synaptic membrane. Neurotransmitters bind with receptors on of the ligand-gated channels of the post- synaptic membrane. 3The post-synaptic membrane depolarizes. The neurotransmitters may elicit inhibitory or excitatory responses 4
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4 The post-synaptic membrane resets ready to receive another signal. The neurotransmitters need to be removed from the cleft. It can diffuse or recycled into the presynaptic membrane. 5
QUESTION 7 The following paragraph refers to muscle contraction. Fill in each of the blanks to complete the paragraph using terms from the list provided. More terms than necessary are provided, and terms may be used more than once.(0.5 mark each; total 3 marks) The action potential spreads along thesarcolemma, until it reaches a T-tubule. The action potential continues down the T-tubule, where it triggers the release ofCa2+from the sarcoplasmic reticulum_____. This exposes binding sites onactin_______.Myosinheads bind to the exposed sites on____actin_____to form cross-bridges. ο·Na+ο·sarcoplasmο·mitochondria ο·K+ο·sarcolemmaο·Golgi apparatus ο·Ca2+ ο·Mg2+ ο·sarcoplasmic reticulum ο·sarcomere ο·myofibril ο·myosin ο·actinο·nucleusο·myofilament QUESTION 8 Think about how the renin-angiotensin-aldosterone system acts to maintain normal blood pressure. Susan has sustained damage to her adrenal glands. Consequently, her circulating levels of aldosterone are abnormally low. A.Where are the target cells for aldosterone located in the body?(1 mark) Distal tubule Collecting ducts B.What do you expect the lack of aldosterone to do to Susanβs blood pressure? Explain your answer.(3 marks) Aldosterone is a steroid hormone responsible for the reabsorption of water along with Na+; elevating blood volume; therefore, raising blood pressure. However, damage to the adrenal glands results in lack production of aldosterone. As a result, Susanβs kidneys will not retain Na+and water as well as excrete K+. Therefore, the homeostatic imbalance of water and salts will result in low blood volume, hence decreased blood pressure. 6
QUESTION 9 Explain the role of baroreceptors in the control of blood pressure during a short period of widespread vasodilation.(3 marks) Baroreceptors line the blood capillaries and help monitor blood pressure changes. Elevated blood pressure stimulates an increased parasympathetic input. Consequently, it results in lower heart rate, vasodilation, and low blood pressure. QUESTION10 Explain the term βnormal sinus rhythmβ.(1 mark) It is the rhythm originating at the sinus node. It describes the typical rhythm of a normal heart. A normal sinus rhythm denotes all the measurements of an electrocardiogram, such as PR and QT intervals are normal. Besides, it denotes a normal P wave axis and heart rate. QUESTION 11 For each of the scenarios below, indicate whether you would you expect resting heart rate to be greater or less than that associated with normal sinus rhythm of a person with average fitness. Explain the cardiac physiology underlying the identified change.(4 marks) Heart rateSituationExplanation Greater A person of average fitness running a 5km fun run. The heart rate rises causing the personβs body to increase cardiac output. It determines the amount of oxygenated blood supply to muscles and tissues. Less An endurance athlete at rest. Endurance athletics increase cardiovascular efficiency; it strengthens the heart muscles that results in larger stoke volume; therefore, greater volumes of oxygen is delivered to the heart and peripheral organs. 7
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QUESTION12 Haemophilia is the oldest known hereditary bleeding disorder. Explain why haemophilia is more commonly seen in males.(3 marks) Haemophilia is a recessive X-linked disorder that is passed to generations through the X chromosome. It is common in males who have XY chromosomes as they inherit a single X chromosome unlike their female counterparts who have XX chromosomes. The males inherit their X and Y chromosomes from their mothers and fathers respectively. Thus, they will have haemophilia when the single X chromosome carries a mutation for the disorder(Wang et al., 2017). QUESTION 13 Tasma is enjoying a night out at the pub with her friends. It is well established that alcohol inhibits the secretion of ADH. Explain how this will affect her urine output.(3 marks) Alcohol acts on pituitary glands by inhibiting the secretion of ADH that regulates the amount of water reabsorbed by the kidneys. Since alcohol acts on the hypothalamus and pituitary glands, it reduces the amounts of ADH in circulation. When ADH reduces in Tasmaβs body, her kidneys wonβt reabsorb more water, thus, more urine output. QUESTION 14 The following table describes the three elementary steps of urine formation. Complete the missing parts of the table.(4 marks total) Step in urine formation (0.5 marks/cell) Where does this step take place? (0.5 marks/cell) What happens? (1 mark/cell) FiltrationGlomerulusBlood passes through the glomerulus at greater pressure pushing water and small molecular weight substances, such as nitrogenous wastes from the blood capillaries into Bowmanβs capsule. 8
The glomerulus retains cells and blood components. ReabsorptionAlong the renal tubuleWater and/or solutes are transported from the tubular lumen to peritubular capillaries (blood) SecretionAlong the length of the tubular network; the exact location depends on the substance being transported Different components such as creatinine are eliminated from the blood via the capillaries to the collecting ducts to form urine: substances nor reabsorbed following glomerular filtration or tubular filtration(Lawrence, Daniel & Raman, 2018). QUESTION 15 The Wiggerβs diagram (below) represents pressure and volume relationships in the left side of the heart during one cardiac cycle. To answer this question, you should focus on the changes in pressure in different chambers of, or vessels leading from, the left side of the heart. For TWO of the labelled points, state which valve is open/closed at that time. Highlight your chosen point inbold. You must also explain WHY that valve opened/closed and where the blood is flowing immediately after this point in time, due to the change in position of the valve. An example is provided.(4 marks) LabelValve (name and open/closed)Explanation A Left AV valve closes The pressure in the left ventricle is greater than in the left atrium. Blood flows from the left ventricle into the left atrium. B Left Semilunar valve opens Ventricular muscles contract generating high pressure than that in the arterial tree. Blood flows to the aorta and pulmonary trunk. CLeft semilunar valve closesThe left ventricles relax. Arterial pressure becomes greater than ventricular pressure making the semilunar valves to close. It prevents the blood flowinto the ventricles. DLeft AV/bicuspid valve opensThe pressure in the left ventricle becomes lower than that in the left atrium. Blood flows from the left atrium to the left ventricle. 9
QUESTION 16 A person with type B blood has been involved in a car accident and excessive bleeding necessitates a blood transfusion. Due to an error by a careless laboratory technician, the person is given type A blood. Explain what will happen.(4 marks) The ABO blood system consists of four blood groups: A, B, AB and O. ABO incompatibility reactions occur when patients are given the wrong blood type, for instance in this case where person with type B blood is given type A blood. Red blood cells contain antigens on their surfaces. Type A and B blood has A and B antigens respectively. Usually, the immune system produces antibodies against antigens that are not recognized in the blood. Thus, the person with type B blood will create antibodies against B antigens following the blood transfusion. The ABO incompatibility reactions will destroy the donorβs blood cells resulting in severe symptoms, such as flank pain, fever, and dizziness(Mitra, Mishra, & Rath, 2014). QUESTION 17 A.Complete the below table of partial pressures in external respiration.(2 marks) 10
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pO2 (mmHg)pCO2 (mmHg) AlveoliHigh; about 100 mmHgLow; about 40 mmHg CapillaryLow; about 40 mmHgHigh; about 45 mmHg B.Use to the figures above to explain how differences in partial pressures drive the direction of gas movement between the blood and alveoli.(2 marks) Gases move from regions of higher partial pressure to the regions of low pressure. As a result, oxygen will move from the alveoli (100 mmHg) into the blood capillaries (40 mmHg). Similarly, carbon (IV) oxide is released from the capillaries (45 mmHg) to the alveoli (40 mmHg). 11
QUESTION 18 The figure below illustrates inspiration and expiration. Refer to this figure to answer the following questions.(0.5 marks each - 3 marks total) QuestionAnswer Contraction of which muscle/s produces the movement labelled "1"? Intercostal muscles; enlarges chest cavity. Contraction of which muscle/s produces the movement labelled β2β? Diaphragm; increases chest cavity for which the lungs expand. At label β3β, is pressure outside greater than or less than pressure inside the lungs? The pressure outside is greater than in the lungs; pressure difference facilitates the movement of air into the lungs: inhalation. Is the pressure in the space labelled "4", higher or lower compared to the atmospheric pressure? Lower than the atmospheric pressure. At label β8β, is pressure outside greater than or less than pressure inside the lungs? The pressure outside is less than that in the lungs; the higher pressure in the lungs flows out: exhalation. Name any ONE muscle that contracts to cause the extra movement required when you need toexpire forcefully (indicated by the arrows labelled "6" and "7"). Abdominal muscles; pushes the diaphragm up which raises alveolar pressure; hence, exhalation. 12
QUESTION 19 The graph below displays the oxygen dissociation curve and factors that affect the release of oxygen from haemoglobin (Hb). According to the graph, list the three factors that affect the release of oxygen into the blood supply of a hard-working skeletal muscle. For each factor, explain how it contributes to the release of oxygen from haemoglobin.(3 marks) Image fromhttp://www.gpnotebook.co.uk/simplepage.cfm?ID=20250669 Partial pressure of oxygen: Gases move from high pressure to low pressure regions. The affinity of oxygen molecules to haemoglobin increase more molecules are bound. As seen from the curve, as the partial pressure of oxygen increases, there is a subsequent increase in the molecules of oxygen that is bound to heme. Thus, partial pressure is critical in determining the extent of binding or dissociation of oxygen to heme at the respiratory and tissue sites(Nagalakshmi, Madhisudhana, Rajendra & Manjunath, 2016). pH: Low pH stimulates the dissociation of oxygen from haemoglobin. By contrast, high pH inhibits the dissociation of oxygen from haemoglobin. Higher carbon (IV) oxide concentration generates more hydrogen ions, thus lower blood pH, which contributes to the release of oxygen. Temperature: High temperature levels stimulate the dissociation of oxygen from haemoglobin. On the contrary, low temperatures inhibit the dissociation of oxygen molecules from the haemoglobin. High- active tissues that release more energy stimulates the dissociation of oxygen from haemoglobin, hence supplying more oxygen to the active tissues (Nagalakshmi et al., 2016). 13
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References Chonchol, M., & Kendrick, J. (2019). Calcium Homeostasis in Kidney Disease.InEndocrine Disorders in Kidney Disease(199-206). Springer, Cham. Lawrence, E. A. (2018). Function of the nephron and the formation of urine.Anaesthesia and intensive care medicine, 19(5), 249-253. doi:10.1016/j.mpaic.2018.03.001 Mitra, R., Mishra, N., & Rath, G. P. (2014). Blood groups systems.Indian journal of anaesthesia, 58(5), 524-528. doi:10.4103/0019-5049.144645 Nagalakshmi, N. V., Madhusudhana, R., Rajendra, N., & Manjunath, A. K. (2016). Hemoglobin and oxygen transport.Karnataka Anaesthesia Journal, 2(1), 1-6. Pereda A. E. (2014). Electrical synapses and their functional interactions with chemical synapses. Nature reviews neuroscience, 15(4), 250-263. doi:10.1038/nrn3708 Wang, M., Cyhaniuk, A., Cooper, D. L., & Lyer, N. N. (2017). Identification of patients with congenital hemophilia in a large electronic health record database.Journal of blood medicine, 8, 131-139. doi:10.2147/JBM.S133616 14