MODULE 8: NON-INFECTIOUS DISEASE AND DISORDERS



MODULE 8: NON-INFECTIOUS DISEASE AND DISORDERS1: Homeostasis—How is an organism’s internal environment maintained in response to a changing external environment?Construct/interpret negative feedback loops that show homeostasis Homeostasis = maintained through nervous and endocrine systems.Homeostatic responses are initiated by external/internal stimuli that is detected by a specific type of receptor. (Chloe Pissed Off To Mexico)Chemoreceptors: detect chemicals, solute concentration, pHPhotoreceptors: detect visible lightOsmoreceptors: detects osmotic pressure Thermoreceptors: detect temperatureMechanoreceptors: detect physical stress, pressure, gravityWhen drawing feedback loops, remember: optimal -> receptors -> control centre -> effector -> response -> optimal.ThermoregulationTypes of organismsEndotherms = internally generated heat, maintained through negative feedback.Ectotherms = external heat sources.Homeotherms = constant body temperature.Poikilotherms = adjust temperature depending on environment.Thermoregulation via nervous systemHypothalamus = control centre, detects changes in body temperature.Skin = contains thermoreceptors, relays info to hypothalamus.Cooling mechanisms:Vasodilation—blood vessels dilate, blood brought to surface -> convective cooling.Sweating—glands release sweat -> evaporative cooling.Heating mechanisms: Vasoconstriction—blood vessels constrict, blood moved away from surface -> retain heat.Shivering—muscles shake, expending energy through cell respiration -> heat produced as by-product.Piloerection—hair stands on end -> trap pockets of warm air.There are also behavioural responses (e.g. burrowing, basking)Blood glucose level regulationRegulated via endocrine system—insulin and glucagon, released from pancreas and act on liver.Blood requires glucose to make ATP (energy), the demand for which fluctuates, so blood glucose level (BGL) must be regulated (too much = hypertonicity, too little = no energy)When glucose is high:Insulin released from beta cells in pancreas -> stimulate glycogenesis (stores glucose in liver) or increases rate of glucose breakdown (cell respiration) -> decrease BGL.When glucose is low:Glucagon released from alpha cells in pancreas -> stimulate glycogenolysis (glycogen breakdown in liver -> release glucose from liver) or decrease rate of glucose breakdown.OsmoregulationTerrestrial animals regulate fluid levels by controlling water released in urine through nervous and endocrine systems.Osmoreceptors in hypothalamus detect water levels in blood and coordinate release of the neurohormone (released by nerve cells, target distant cells) anti-diuretic hormone (ADH).When blood water is low:More ADH released from posterior pituitary -> stimulates production of aquaporins in collecting ducts of kidneys, making them more permeable -> more water reabsorbed into bloodstream.When blood water is high:Less ADH released from posterior pituitary -> less aquaporins in collecting ducts, making them less permeable -> less water absorbed into bloodstream, more lost in urine.Investigate mechanisms used by organisms to maintain their internal environment within tolerance limitsTrends/patterns in behavioural, structural and physiological adaptations in endotherms that maintain homeostasisAdaptation = characteristic that will increase survival and reproductive chances.Maintain homeostasis by regulating e.g. temperature, glucose.Behavioural—how an organism acts.Incl. burrowing, nocturnal activity, migration.E.g. Bilby—nocturnal, sleeps in burrows in hot parts of day and hunts at night to lessen exposure to heat.E.g. red kangaroo—basks in sun / licks forelegs to increase evaporative cooling.Structural—physical characteristics.Incl. Insulation, shape of structures, SA:V ratio in shape/size of structures.E.g. bottlenose dolphin—tapered shape and small limbs decreases exposure to cold, thick blubber insulates from cold.E.g. red kangaroo—insulation through fur / exposed skin on forelegs to increase cooling.Physiological—how the body functions, often relates to biochemical reactions.Incl. changes to metabolic rate, hibernation, evaporative cooling, regulation of blood flow to surface.E.g. mountain pygmy possum uses torpor (similar to hibernation) during winter, in which they reduce their metabolism by up to 98% for up to 6 days -> conserve energy and reduce food requirement.E.g. red kangaroo—increased / decreased metabolic rate.Internal coordination systems that allow homeostasis to be maintained, incl. hormones and neural pathwaysTo survive a range of conditions, the body must detect and respond to changes. The maintenance of a stable internal environment within tolerable limits = homeostasis, regulated by negative feedback.The Nervous SystemContains specialised network of cells (neurons), coordinates actions through transmission of electrochemical signals.Central Nervous System (PNS)= brain and spinal cord.Made up of grey matter (neuron cell bodies) and white matter (nerve fibres surrounded by myelin sheaths).Brain = control centre, maintains homeostasis.Hypothalamus = small area of brain close to pituitary gland. Control centre for many homeostatic processes. Directs effectors to carry out a response through electrical messages or hormones. Main link between nervous and endocrine system.Spinal cord = transmits messages from receptor organs (eyes, ears, skin, etc.) via sensory neurons to the brain, and transmits nerve impulses from the brain to effectors. Also coordinates reflex actions.Peripheral Nervous System (PNS)Made up of peripheral nerve cells/neurons that link the CNS with the body’s receptors and effectors.336994576932400-60642585623200Neurons generally consist of a cell body (contains a nucleus and organelles, form grey matter of CNS), dendrites (extensions of the cytoplasm, receive messages from axons and convey them towards cell body), axon (single, long extension of cytoplasm, conduct messages away from cell body, form white matter)Types of neuronsSensory: Conduct nerve impulses from receptors -> CNSRelay: Conduct nerve impulses within CNSMotor: Conduct nerve impulses from CNS -> effectorsStimulus-response model= basic pathway for a nerve impulse.Stimulus -> receptor -> control centre -> effector -> response.Receptor converts stimulus into nerve impulse, this is transmitted by sensory neuron to CNS.Relay neurons in CNS transmit signal to control centre.Motor neurons transmit resultant nerve impulse from CNS to effector organ (muscle/gland) -> appropriate response.Transmission of nerve impulse within a neuronOccurs via movement of electrical potential along length of neuron.When neuron isn’t firing, charge difference across membrane is negative—resting potential.When it is firing, charge difference is slightly positive—action potential.Change in membrane polarity from resting to action potential = depolarisationRestoration of resting potential = repolarisation.Generation of resting potentialSodium-potassium pump maintains electrochemical gradient of resting potential.This pump = transmembrane protein that uses active transport to exchange sodium and potassium ions across membrane, expelling 3 positive sodium ions for every 2 positive potassium ions admitted -> membrane remains negative -> resting potential.Transmission of action potentialSodium (Na) and potassium (K) channels are voltage-gated = they open/close based on voltage across membrane.In response to a signal at a sensory receptor/dendrite, sodium channels open and Na enters neuron -> membrane potential becomes positive (depolarisation)If sufficient change in membrane potential is achieved (threshold potential), adjacent Na channels open -> wave of depolarisation that spreads down axon.Change in potential -> opens K channels -> K exits neuron -> membrane potential becomes negative (repolarisation).Before neuron fires again, original ion distribution must be re-established (refractory period) -> impulses travel only one direction.Transmission of nerve impulse between neuronsJunction between two neurons = synapse.Action potential (electric signal) cannot cross the synapse, so triggers release of chemicals (neurotransmitters) to continue signal.Chemical transfer across synapsesWhen action potential reaches axon terminal, it triggers opening of voltage-gated calcium (Ca+) channels.Ca ions diffuse into cell and cause vesicles to release neurotransmitters, which are released from axon terminal through exocytosis and cross synapse.Neurotransmitters bind to neuroreceptors on post-synaptic membrane, and if threshold potential is met in post-synaptic neuron, signal is triggered and continued.The Endocrine System= a system of glands that secrete hormones (chemical messengers) into the bloodstream to regulate bodily functions.Glands are stimulated by nervous system messages, other hormones, or receptors in a gland.Pituitary gland = master gland, regulates activity of other glands.Hormones achieve homeostasis by influencing the activity of certain enzymes/their concentration in target cells.Ways hormones induce cell activity:Changing membrane polarity/permeabilityRegulating expression of proteins through gene activation/suppressionModerating enzyme activity through activation/deactivation (e.g. altering cell metabolism)Inducing/suppressing release of chemicals (e.g. pituitary gland releasing prolactin to stimulate lactation)Stimulating mitosis/meiosisTypes of hormones:Steroids—lipids derived from cholesterol, constitutive, e.g. testosterone/estrogenPeptides—short polypeptide chains, regulatory, e.g. insulinAmine—derived from aromatic amino acid, regulatory, e.g. thyroxineExamples:Testes secrete testosterone to help development of male reproductive tissues and promoting secondary sex characteristics.Pancreas secretes insulin and glucagon to control blood glucose level.Thyroxine secreted by thyroid gland to assist brain development and bone maintenance.Mechanisms in plants that allow water balance to be maintainedWater is lost when stomata open for gas exchange, and through transpiration -> lifts water/ions to top of plants through transpiration stream, provides evaporative cooling.Xerophytes—plants adapted for arid conditions, halophytes—salt tolerant plants.AdaptationEffectThick waxy/leathery cuticlePrevent loss of water through evaporation.White hairsReflect sunlight -> reduce temperature and evaporation.Leaves oriented so stomata aren’t exposed to direct light.Reduce evaporation.Reduced surface area of leaves, e.g. divided into pinnae/leaflets, or reduced to small scales with photosynthetic function taken over by other organs such as cladodes (photosynthetic stems) and phyllodes (leaf stalks).Reduce evaporation.Only opening stomata in cooler parts of the day.Reduce evaporation.Hairy/rolled leaves, sunken stomatatrap water and keep the air around the plant humid -> prevent evaporationFleshy stems/leaves of succulents swell and retain moistureUsed to survive during dry periods.Woody fruits instead of fleshyReduce water loss when fruit falls off plant.Deep root systemTap into deeper water table.Shallow root systemAbsorb overnight condensation.center3402412: Causes and effects—Do non-infectious diseases cause more deaths than infectious diseases?Investigate causes/effects of non-infectious diseases in humansGenetic diseasesCaused by genetic mutations—can be single gene/point (e.g. haemophilia, sickle cell anaemia), or chromosomal (e.g. incorrect chromosome no—Down Syndrome)Down Syndrome (trisomy 21): caused by an extra copy of chromosome 21, occurs by non-disjunction (happens in meiosis, mitosis or fertilisation) or translocation. Symptoms—heart defects, mental disability, wide-set eyes.Diseases caused by environmental exposureCaused by exposure to toxic substances (carcinogens, pollutants, heavy metals), radiation (X-rays, nuclear, UV), drug abuse (alcohol, nicotine), stress, excessive noise, mechanical trauma.253047526733500Minamata disease (mercury poisoning): occurred first in Minamata City, Japan. Caused by heavy metal poisoning by mercury of fish/shellfish from polluted waters. Effects—paralysis, convulsions, fever.Atherosclerosis (see picture): Risk factors—lack of exercise, smoking, saturated fats/salt. Effects—calcified plaque builds in arteries -> hardening of arteries, hypertension (increased blood pressure) -> stroke/cardiac arrest if clot forms.Nutritional diseasesCaused by excessive food intake (obesity) or insufficient intake (anorexia nervosa). Also includes deficiency diseases.Anaemia: caused by lack of iron. Effects—pale skin, weakness, fatigue.Scurvy: caused by lack of Vitamin C (found in citrus fruits, used for tissue growth and repair). Effects—loss of appetite, weakness, brittle bones, bleeding gums.383794011493500CancerCause: DNA mutations (e.g. inherited mutation, radiation, toxic waste, mutagens known as carcinogens, risk factors-smoking, diet, alcohol) Effects: Uncontrolled cell division, prevents cells differentiating into specialised forms, tumour formation, malignant tumours spread to/disrupt other tissues, death.Genes that control normal cell division:DNA repair genes—code for proteins that repair damaged DNA. Mutations here = DNA not repaired, damaged DNA replicated.Proto-oncogenes—code for proteins that cause cell growth and mitosis. Mutations = uncontrolled cell production, prevents cell death.Tumour suppressor genes—code for proteins that slow/stop cell growth and mitosis. Mutations = cell division/death not controlled.Metastasis = secondary malignant growth away from primary cancer site (growth has same cell type as original tumour)Bowel cancer: growth on inner lining of large intestine/rectum, can be soft/friable or hard/fibrous. Risk factors—smoking, obesity, family history. Symptoms—diarrhoea/constipation, weight loss, abdominal pain. Collect/represent data to show the incidence, prevalence and mortality rates of non-infectious diseasesNutritional diseasesDiseases caused by environmental exposureSee ‘Analyse patterns of non-infectious disease in populations, incl. incidence and prevalence’ under 3: Epidemiology3: Epidemiology—Why are epidemiological studies used?Epidemiology = study of disease incidence, prevalence, mortality rates and distribution in different groups using statistical analysis.Aims to establish disease cause, guide development of strategies to improve health, and evaluate effectiveness of current strategies.Correlation doesn’t always = causation.Measures:Incidence (new cases in time period)Prevalence (no. of people affected at certain time)Mortality (deaths)Determinants (risk factors, e.g. age, smoking)To be valid, it must:Use large groups of people and relate to a target population.Use populations w/ disease occurrence and with differing exposure to potential causes.Allow for analysis of risk factors.Types of epidemiological studies:(Observational) Descriptive—first investigation, looks for patterns, aims to narrow range of causes(Observational) Analytical—Follows descriptive, more detailed. Aims to refine patterns, collect data (prevalence, incidence, mortality), refine possible cause range.Case-control—Compares un-diseased people with diseased people, looks for differences in exposure to possible causes.Cohort—Follows cohort over years with regular examinations. Group differs in exposure -> compare disease incidence over time.Intervention—test treatment/health campaign effectiveness, aiming to change behaviour and reduce disease incidence. Experimental—People randomly put into 2 groups. One group receives treatment, one receives placebo.Quasi-experimental—Researcher chooses subjects.Errors:Random—unpredictable, reduce accuracy but don’t skew results.Systematic—e.g. selection bias, information bias -> skew results from true results.Analyse patterns of non-infectious disease in populations, incl. incidence and prevalenceNutritional diseasesDiabetesPrevalence: affects 6% of Australian adultsPrevalence = 2% higher for men, increases rapidly up to age 75Contributed to 11% of deaths in 2017Trends: incidence gradually increasing (due to increasing obesity and improving diagnostic methods)Twice as high for lowest SES than highest SESHigher in rural/remote areasATSI people 4x more likely to have diabetes than non-indigenous peopleGlobal prevalence—risen by about 4% since 1980, rising faster in middle/low income countriesAmerican Diabetes Association—found 69% of respondents with type 2 diabetes reported no/less than recommended physical activity, 62% eat less than recommended fruit/veg servings per day, 82% were overweight/obese.Diseases caused by environmental exposure Lung CancerRecognised link between smoking and lung cancer, smoking linked to certain age groups, occupations and alcohol consumption.As age increases, death rates increase.Smoking causes an average of 2.9% of hospitalisations in Australia, and cause an average of 14.4% of deaths (about 8% higher in males)Melanoma (skin cancer)Australia = highest rate of skin cancer.Melanoma = type of skin cancer.1/18 Australians are diagnosed with melanoma before they turn 85.Most common cancer in Australians aged 15-29.Investigate treatment/management and future directions of research of a non-infectious disease (lung cancer)Treatment/management carried out by a multidisciplinary team of medical and allied health professionals.Methods are based on patient’s health and personal preference; and the cancer type, stage, location and severity.Management—intervention programs to monitor and improve outcomes.Treatment (can also be used to manage) involves one or more of the following, and may take years: (CRITS)Surgery—invasive, involves removing cancerous and surrounding tissue (wedge resection).Radiation therapy—high-powered radiation rays kill cancer cells by damaging their DNA, can be carried out externally or internally (e.g. through tubes). Can relieve pain in advanced cancer, side effects include skin problems and fatigue.Chemotherapy—uses drugs to kill/slow cancer, also damages healthy cells. Used in cycles, w/ periods of rest to allow cells to recover. Often used after surgery/radiation to kill remaining cancer cells.Targeted drug therapy—substances kill/block growth of cells without harming healthy cells. Must be matched to patient’s gene/caner type, may be given in cycles.Immunotherapy—boosts immune system to fight cancer and removes barriers produced by cancer to block immune system.Future directions of researchDevelop greater variety of targeted therapy and immunotherapy drugsVaccines/screening programs for early detection and interventionGenetic/molecular profiling of tumour/patient to allow more personalised and effective treatment.Evaluate method used in an example (Pima Indian population) of an epidemiological studyPima Indians = Arizona Native-American population.Through an analytical cohort study (compared two groups with differing exposure to disease cause over a period of time), examined role of physical activity in developing type 2 diabetes.Found that for both genders, decreased physical activity leads to increased diabetes rates.EvaluationSatisfies large sample size and long examination period—carried out between 1987-2000 (13yrs) with 1728 non-diabetic Pima Indians between 15-59 -> increase reliability.Satisfies cohort study—non-diabetic Pima Indians from same areas and ages studied every over 13yrs, variation = physical activity levelsIncidence calculated for individual age groups, genders and physical activity levels -> determine risk factors/groups.Same Pima Indians examined every 2 years over 13 years -> reliable, valid.Objective, scientifically approved methods and data (e.g. glucose tests, physical examinations, medical history records, reliable records of leisure/occupation-related activity) used to judge activity levels and diagnose diabetes.Scientifically tested/reliable models used to analyse incidence of diabetes in relation to activity and BMI.Scientifically valid and unbiased questions by trained interviewers used to determine activity levels.Trained interviewers would judge when activity levels are incorrectly/insufficiently reported, and remove these results -> increase accuracy/validity.Report peer reviewed before publication -> reduce bias, increase validity.Therefore, the epidemiological study is valid and reliable, following epidemiological principles.Evaluate, using examples, benefits of engaging in an epidemiological studyAllows research into the causes/risk factors, vulnerable groups and effects of infectious disease, non-infectious diseases, and events such as suicide and car accidents -> allows effective intervention and prevention. Health resources may be allocated to groups/areas most in need. Allow public health authorities to manage, evaluate and plan for health services to prevent, control and treat disease.Used to develop health promotion strategies/policies (e.g. health warnings on cigarette packets)E.g. ATSI people—studies by AIHW show that the burden of the disease is over 2x higher for ATSI people -> resources can be allocated in areas of ATSI disease; 19% of ATSI burden caused by mental health/substance issues -> highlight need to increase awareness and change attitudes (such as ensuring counsellors/teachers in ATSI schools are educated about ATSI culture and issues)E.g. Pima Indians—study showed that decreased physical activity increased diabetes rates -> health promotion can promote exercise to reduce diabetes incidence)All of this ultimately decreases future disease occurrence/severity. 4: Prevention—How can non-infectious diseases be prevented?Use secondary sources to evaluate effectiveness of current disease-prevention methods and develop strategies for the prevention of a non-infectious diseaseEducational programs and campaignsPublic health programs Aim to improve health and prevent disease by raising awareness and empowering people to make healthy choices.Should be diverse to reach different population groups.Includes health education, risk factor monitoring, taxes (e.g. sugar tax), disease detection/prevention.Local/federal governments and NGOs (e.g. Cancer Council, Heart Foundation) fund research, initiatives, treatment, promotion, etc.E.g. QUIT—decreased smoking prevalence and incidence/mortality rates of lung cancer (smoking prevalence decreased from 27.7% in 1990 to 14.7% in 2014-15 following the National Tobacco Campaign, plain packaging, bans on tobacco advertising, etc.)Educational programsEducate public about risk factors (e.g. sun exposure -> skin cancer, poor diet -> diabetes)Promote healthy choices, vaccinations, check-ups, support networks.E.g. Slip, Slop, Slap (Cancer Council); No hat, no playE.g. Work, Health, Safety legislation—codes of practice reduce diseases caused by environmental exposure, e.g. asbestosis.Screening programsTesting/examining people for disease.May be offered to certain groups based on sex, age, ethnicity, family history, etc.Regular screening = increase accuracy.E.g. BreastScreen—free mammograms for women over 50 to test for breast cancer -> increase chances of effective treatment and survival.Prenatal screening—blood tests/ultrasound for pregnant women to test for conditions such as Down Syndrome.National Cervical Screening Program—detects early changes in the cervix, recommended for women between 18 and 69 who were/are sexually active. Involves five-yearly Cervical Screening Test which also tests for HPV with increases risk of cancer.Genetic engineeringInvolves genetically modifying cells to treat/prevent disease.Genetically modified cellsUsed to study cellular processes and create/improve cell-based therapiesE.g. Peter MacCallum Cancer Centre is looking for ways to boost specific T cell numbers in cancer patients—T cells removed from patient, modified with TCR genes that code for receptors that make T cells more able to target cancer cells. They are then grown in vitro and returned to the patient.Recombinant DNA technologyInvolves inserting genes from an organism into a different type of organismE.g. transgenic mice to test cancer drugs/treatmentsE.g. cloning insulin by inserting the human insulin gene into a bacterial plasmid and allowing it to grow by mitosis. Replaced extraction of insulin from pigs/cattle—expensive, time consuming, risk of allergic reaction and disease.Gene therapyGenetic material used to treat diseases caused by missing/dysfunctional genes.Issues of safety, ethics, cost. Delivering genes in eukaryotic cells is risky.Only works on individuals, as it involves only somatic (body) cells.Viral vectors—used to transfer therapeutic genes (e.g. adeno-associated virus), modified to carry a gene and not induce an immune response. Can insert a gene into the chromosome -> permanently produce gene, but risk of mutation.Direct delivery—gene put in viral vector, injected into patient, travels to target organ.Cell-based delivery—vector-packaged therapeutic gene, embryonic stem cells and adult stem cells grown in vitro then inserted int patient.E.g. Haemophilia, replacement therapy—adeno-associated viral proteins carry Factor IX (gene for clotting protein) to the liver -> reduces symptoms.LiposomesSmall phospholipid vesicles that can diffuse across cell membranes/enter cells through endocytosisDNA is inserted into liposome, carried into cell, and released.Can be safer than viral vectors.Strategies for prevention of severe combined immunodeficiencySCID = genetic disorder, deficiency in enzyme adenosine deaminase -> often destroys T cells needed for immune response.Hematopoietic stem cell transplant -> improve T cell production and immune response.Gene therapy—retrovirus viral vector introduces human adenosine deaminase gene to increase T cell production. Often effective in immune system restoration, but can lead to leukaemia -> current methods use self-inactivated retroviruses to decrease disease likelihood.5: Technologies and Disorders—How can technologies be used to assist people who experience disorders?Explain a range of causes of disorders by investigating structures/functions of relevant organsHearing lossEar—structure and function (PATOORCOA) (Pretty Adventurous Tropical Orangutans Overthrow Ruthless Communist Overlord Alligators)StructureAnatomyFunctionOuter earPinnaLarge external part of earFunnels sound waves into earAuditory canalHollow canal leading into earFunnels sound waves to tympanic membraneMiddle earTympanic membrane Eardrum, membrane stretching across canalVibrates when sound waves reach it, pass vibrations to ossiclesOssiclesThree tiny bonesAmplify/conduct vibrations from tympanic membraneOval windowThin membranePicks up vibrations from ossicles and passes them into cochlear fluidRound windowThin membraneDissipates vibrations and allows pressure differences in cochleaInner earCochleaSpiral coiled, fluid filled tubeContains receptor hair cellsOrgan of CortiSmall spiral organ within the cochleaConverts mechanical energy (vibrations) -> electrochemical energy (nerve impulses)Auditory nerveNerve from ear to brainTransmits electrochemical signals to brain to be interpretedDisorder—hearing lossConductive hearing lossCaused by issue with mechanical conduction of vibrations through outer and middle ear.Causes: Malformation of ear structures, perforated (has holes) ear drum, ear infections, damage to ossicles due to trauma (e.g. loud noise).Affects loudness of sound.Sensorineural hearing lossCaused by damage to/malformation of inner ear.Causes: Excessive noise exposure, birth defects, heredity, infections, tumours, ageing.Affects loudness and clarity of sound, usually permanent.Prevents mechanical energy of vibrations from being transformed into electrical impulses.Visual disordersEyes—structure and function (CCSAIPLCPRCROBE)StructureAnatomyFunctionConjunctivaClear epithelial cells across front surface of eyeProtect front of eye, lubricates cornea.CorneaMembrane over front of eyeballProtects eye, refracts light rays to direct them into lensScleraTough layer, forms white of eyeProtects eye, holds fluid and spherical shapeAnterior chamberBetween cornea and lens—contains aqueous humourLubricates eye, holds shape, refracts lightChoroidBlack layer between sclera and retina with many blood vessels, forms iris.Provides blood supply, prevents false images.IrisMuscular ring—extension of choroid.Contract/dilate to regulate pupil size, blocks excess light.PupilOpening at front of eye.Changes size to control light entering eye.LensFlexible disc behind iris.Blocks UV, changes shape/thickness through accommodation to focus light onto retina.Ciliary bodyEncircles lens with ligaments and muscle.Holds lens in position, changes its thickness.Posterior chamberContains vitreous humour—between lens and retina.Maintains shape of eyeball, refracts light, hydrates.RetinaSensory layer in back of eyeball, holds photoreceptor cells and neurons.Converts light -> electrochemical energy.Cone cellsPhotoreceptor neurons, denser towards edge of retina.Responds to bright light and colours.Rod cellsPhotoreceptors, denser towards edge of retina.Responds to dim light and movement.Optic nerveNerve between aye and brain.Carries nerve signals about images to brain.Blind spotSmall area of retina where optic nerve exits.No photoreceptorsEye musclesMuscles attached from eyeball to boneHolds/rotates eyeballAccommodationUsed to focus on objects by changing thickness of lensMaximum accommodation: Lens is rounded, refractive power is high used to look at close objects.At rest: Lens is flatter, refractive power is low, used to look at distant objects.DisordersMyopia (short-sightedness)Distant objects appear blurred.Causes: Elongated eyeball, inadequate refractive power in cornea, lens may not flatten enough.Hyperopia (long-sightedness)Near objects appear out of focus.Causes: Eyeball too rounded, lens too flat (e.g. due to loss of elasticity in old age), refractive power too high.CataractsLens grows cloudy and opaque -> prevents light entering retina -> eventual blindness.Causes: Aging, metabolic disorders, trauma, heredity.AstigmatismCornea/lens curvature is irregularly shaped -> blurred vision.Macular degenerationDegeneration of retinal pigment epithelium beneath the retina.Prevents light from being focused to retina -> loss of central vision.Causes: Smoking, unhealthy diet, UV light exposure.Loss of kidney functionThe kidney regulates salt and water levels in the blood, and filters out toxic substances to be excreted in the urine. Blood exiting through the renal vein has less urea (removed to form urine), water, solutes, ions (depends on hydration) glucose, oxygen (used to generate energy), and more carbon dioxide (by-product).2221747606900FiltrationBlood enters the kidney through the renal artery then travels through blood vessels to nephrons.Blood enters the nephron’s glomerulus capillary and becomes glomerular blood. This capillary travels into the Bowman’s capsule, and any substances (nitrogenous waste, amino acids, glucose, salt ions) in the blood small enough pass through the glomerular walls into the Bowman’s capsule, leaving large molecules (blood cells, proteins) in the blood.This fluid (glomerular filtrate) flows out the proximal tubule at the back of the capsule (proximal tubule -> loop of Henle -> distal tubule -> collecting tubules)243447259365ReabsorptionReturns essential components that have been filtered out of the blood to the bloodstream (e.g. amino acids, glucose, ions, vitamins).Reabsorbed solutes move by active transport and facilitated diffusion in the proximal and distal tubule.In the ascending Loop of Henle and the collecting duct, ions (mostly sodium) are actively pumped into the medulla -> water concentration of medulla becomes lower than that of tissues -> water moves from Loop of Henle and collecting duct into medulla by osmosis, so it may be reabsorbed into the blood.SecretionInvolves removal of toxic substances (e.g. metabolic wastes—urea, ammonia, hydrogen; drugs—penicillin, morphine) from blood capillaries and tissues surrounding tubules by actively moving/diffusing them into tubules for removal.Most substances are secreted into the proximal tubule, while urea is secreted into the descending loop of Henle (as other tubule areas are impermeable to urea).OsmoregulationHormone aldosterone stimulates reabsorption of salt in the loop of Henle -> regulate salt/water balance in kidney.Antidiuretic hormone (ADH) stimulates reabsorption of water in the kidney.Disorders—Loss of kidney functionTypes of kidney disease include:Kidney stones—rock hard crystals in kidneysPolycystic kidney disease—inherited, causes cystsDiabetic kidney disease—damage caused by diabetesGlomerulonephritis—inflammation of glomeruli (kidney’s filters)Kidney infection—urinary tract infection affecting kidneysKidney cancer—rare Loss of kidney functions occurs graduallyCauses include:Diabetes—high blood glucose -> kidneys filter more blood -> stress/damage to nephrons -> larger molecules (e.g. proteins) can leak into tubules -> blockages -> further damage.High blood pressure—high force of blood pushed into glomerulus -> damages nephrons -> leakages of large molecules, further damage.Kidney infections—this and prolonged use of certain medications can damage nephrons and kidney function.Kidney stones/tumours/other blockages—urine backs up into kidney -> pressure build up -> kidney damage -> complete shutdown.Damage to nephrons (filtering units) -> cannot carry out filtering, reabsorption and secretion -> cannot remove waste effectively or balance salt/water levels. Symptoms: nausea, fatigue, muscle cramps, changes in urine volume produced, itching.Investigate technologies used to assist with effects of a disorderHearing loss—cochlear implants, bone conduction implants, hearing aidsTechnologyStructureFunctionHearing aidsElectronic amplification devices—contain microphone (detect sound), device (modulate sound), amplifier (increase volume), and battery.Some fit behind ear, some in ear canal.New features—improved battery, decreased size, tailoring to individual need.Assists with deafness caused by damage to outer/middle ear.Amplifies vibrations that pass into the ossicles.If fitted as early as possible (to avoid sensory deprivation), can improve impact of hearing disorders.HearablesAKA smart headphones, new technologyWireless earpiece device containing a microcomputerFits into ear canalAssists with mild hearing lossUses wireless technology to connect with other devices (e.g. smartphone)Sound output of music, audio, phone conversation and biometric monitoring (e.g. heart rate) is fed into ear canal.Cochlear implantHas an external sound processor and an implant/processor under the skin attached to an electrode array in the inner ear.Very expensive (~$40,000), side-effects, quality of sound varies.Assists people who are mostly/completely deaf.Replaces function of damaged sensory hair cells in cochlea -> improve clarity of sound.Receiver picks up sound, passes it to processor, which transmits signals to receiver.Visual disorders—spectacles, laser surgeryTechnologyStructureFunctionSpectacles Frames that hold corrective lenses made of clear, hard plastic. Can be concave or convex.Myopia is corrected through concave lenses—thinner towards centre, bends light rays outwards -> they diverge before meeting the eye, extending focal length -> image falls on retina.Hyperopia is corrected through convex lenses—thinner towards edges, bends light inwards -> converges before reaching eye, shortening focal length -> image falls on retina.Contact lensesSmall lenses shaped to fit curvature of eye, worn on surface of eyeWork the same as glassesLaser surgeryThin flap of corneal tissue cut outTissue folded back and laser beam applied to corneaFlap returnedContacts worn for a week -> hold flap in place.Reshapes the curvature of the cornea -> light enters the eye and hits the retina in the correct fashion.Bionic eyeConsists of camera attached to pair of glasses and microchip implanted in eye. Restores vision to people with retinitis pigmentosa (where rod and cone cells degenerate) and macular degeneration.Camera transmits radio-signals to a microchip in the eye.Electrodes on the chip convert these signals into electrical impulses -> stimulate cells in the retina to convert light rays into electrical impulses -> sent to brain via optic nerve.Loss of kidney function—dialysisRenal dialysisIf kidney function has decreased to 10-15%, dialysis is needed to keep one alive while they wait for a kidney transplant.Blood is removed and pumped through a dialyzer.Dialyzer contains a semi-permeable porous membrane, which mimics the selective absorption of materials into the Bowman’s capsule using artificial porous.261556527277000Fresh dialysis fluid is returned to the patient as wastes are removed and water/solute concentration is maintained.Peritoneal dialysisDone at home—dialysis occurs inside body and patient continues with everyday life.Involves flushing of whole abdominal cavity—30cm catheter tube inserted into abdomen and remains there.Often used for children.281337517989700HaemodialysisCan be done at home through specialised equipment or through regular trips to dialysis clinic.Machine acts as artificial kidney to filter patient’s blood.Mimics filtration—small solute molecules diffuse through semi-permeable dialysing membrane, leaving larger proteins and cells.Time consuming and expensive, severe work and travel restraints—4-5 hours 3+ times per week.Kidney transplantProvides treatment for kidney disease -> longer, more active life.However, the kidney must be a suitable match, and the waiting time in Australia is over three years. Kidney allocation is decided by national guidelines and usually kept anonymous.Australian Paired Kidney Exchange Program uses computer software to search database of recipient/donor kidneys to look for compatible matches.Deceased donor—person who has died with healthy organs, and has registered to be an organ donor/family has decided. Living donor—may be related by blood to recipient, unrelated but known, or anonymous (non-directed kidney donation to recipient on waiting list).Surgical procedure = 2-3 hours, recovery = days.New kidney connected to bladder and carefully monitored until normal function.Evaluate effectiveness of a technology used to manage and assist with effects of a disorderKidney transplantsVery successful—In Australia, over 94% are working a year after surgery.Increases freedom and potential to live long, active life.However, waiting time is over 3 years and person needs to be healthy to have a transplant—surgery and anti-rejection drugs put strain on the body.Medication that suppresses the immune system to prevent rejection of the organ must be taken for the life of the kidney -> make person more prone to serious illness (infections, cancers).Testing for these illnesses is usually carried out on a weekly basis.Restrictions on vaccinations—live vaccines (e.g. TB, measles) aren’t safe for those with transplants.Restrictions on medications—anti-rejection medications don’t combine well with some medications for e.g. malaria, altitude sickness, leading to transplant drug toxicity.Therefore—successful in allowing effective kidney function and a longer, more free life; but waiting time is long and transplant places limitations on vaccinations and medications, and makes recipient more prone to serious illnesses. ................
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