Homeostasis Inquiry question: How is an organism’s internal environment maintained in response to a changing external environment?

● Construct and interpret negative feedback loops that show homeostasis by using a range of sources, including but not limited to:’

Homeostasis is the maintenance of a relatively stable internal environment in response to a changing external environment. The process of homeostasis involves:

- Detecting changes from the stable state - Counteracting changes from the stable state in a negative feedback loop

Feedback refers to the bodies efforts to detect change, put in pace an action to adjust the change then to send a message (feedback) about the change. This is a continuous process. If the change back to far, the feedback tells the body this and further actions will be initiated to maintain homeostasis.

Sense Organ Receptor What Stimuli it Detects

Skin Thermoreceptors Mechanoreceptors

Heat Pressure, movement

Ears Mechanoreceptors Sound

Eyes Photoreceptor Light

Nose // Tongue Chemoreceptors Chemicals Homeostasis usually involves a feedback mechanism. In a feedback mechanism the response is monitored.

In a negative feedback system a specific change results in a response opposite to the initial situation. E.g. body temperature In a positive feedback system the monitoring will reinforce and amplify a situation. E.g. during childbirth oxytocin is released to cause contractions. As the baby’s head pushes on the cervix more oxytocin is released (causing more contractions)

➢ Temperature

How organisms exchange heat with their environment:

- Conduction ~ Occurs when the temperature of the organism and the environment are different.

- Convection ~ Is the transmission of heat from a warmer region to a colder region, resulting from the movement of liquid or gas.

- Radiation ~ Is heat transfer via electromagnetic energy. - Evaporative Cooling ~ Occurs as energy and us lost through a phase state

change from water to water vapour. Mechanism humans use to produce heat:

- Voluntary Movement ~ During physical effort, the amount of heat produced by the muscles is increased

- Shivering Thermogenesis ~ The production of metabolic heat is increased through shivering. It is stimulated by adrenaline

- Increasing Metabolism (the rate of cellular respiration) ~ Metabolic processes as the internal organs are the main source of heat production when the organism is at rest.

➢ Glucose

● Investigate the various mechanisms used by organisms to maintain their internal

environment within tolerance limits, including: ➢ Trends and patterns in behavioural, structural and physiological

adaptations in endotherms that assist in maintaining homeostasis Animals are either ectothermic (poikilothermic) or endothermic (homoiothermic). The only endotherms are the birds and mammals, where the body temperature is kept relatively constant even when the environment temperature fluctuates widely. All other animals are ectotherms, where body temperature varies with environmental temperature. The activity of ectotherms is affected by environmental temperature. As the environmental temperature rises they become more active and as the temperature falls, they become sluggish and lethargic. Such animals are restricted in the habitat they can occupy since they are at the mercy of environmental temperatures. Endotherms on the other hand, because of their constant body temperature, can remain very active in varying environmental temperatures and have therefore successfully invaded a greater range of habitats on earth. Physiological ~ Internal and/or cellular features of an organism that enable them to survive in their environment (e.g. snakes produce poisonous venom to ward off predators and to capture prey). Structural ~ Physical features of an organism that enable them to survive in their environment (e.g. a penguin has blubber to protect itself from freezing temperatures).

Behavioral ~ Actions of an organism that enable them to survive in their environment (e.g. bears hibernate in winter to escape the cold temperatures and preserve energy).

➢ Internal coordination systems that allow homeostasis to be maintained, including hormones and neural pathways

There are two main coordination systems that maintain homeostasis. The nervous system (NS) and endocrine system both communicate with each other to maintain homeostasis. The nervous system consists of the central nervous system (CNS) which is the brain and spinal cord, and the peripheral nervous system (PNS) which are the nerves. The N.S. recieves info (stimuli) from the environment via sensors which contain receptors. A message is sent from a sense organ via sensory nerves (neurons) to the CNS which coordinates a response. A message is sent from the CNS via motor neurons to effector organs (muscles // glands) which carry out a response. Nerve impulse is an electrochemical signal and is very fast. The endocrine system consists of glands that secrete hormones. These are chemical signaling molecules that regulate homeostasis in animals and plants. When a hormone is released by a gland it will interact with a target cell to regulate cell activity (e.g. growth // metabolism). The master gland is the pituitary gland. This controls the release of other hormones into the circulatory system. The endocrine system works more slowly than the N.S.

➢ Mechanisms in plants that allow water balance to be maintained Plants may be adapted in a number of ways which allow them to balance water levels. Mechanisms for water retention are observed widely in Australian flora, as they are often subject to harsh, drought like conditions. Firstly, we need to recall the process of water transport in plants (Transpiration Cohesion Tension theory). Theory of Transpiration Cohesion Tension theory: the mechanism by which water flows through the xylem of plants is due to the combined effects of:

- Transpiration (evaporation of water through the stomata of plants) - Cohesion (that water molecules are attracted to each other, so will move in a

cohesive stream) - Tension (water molecules are attracted to the surfaces which they touch)

By regulating the levels at which transcription occurs, plants are able to retain or release water as required. This may be achieved by:

- Smaller Leaves: Reduces surface area to volume ratio (reducing surface available for transcription reduces water loss)

- Closing Stomates: Inhibits ability for water to leave the plant through the leaves. - Movement: Angling leaves away from the sun at different times of the day may

reduce rates of transcription spiration (cooler temperatures result in less evaporation)

- Dropping leaves during summer and droughts: Conserves water to essential parts of plant

- Large cavities for water storage in stems // trunks Causes and Effects Inquiry question: Do non-infectious diseases cause more deaths than infectious diseases?

● Investigate the causes and effects of non-infectious diseases in humans, including but not limited to: ➢ Genetic diseases

Chromosome // gene abnormalities (e.g. Down's syndrome)

➢ Diseases caused by environmental exposure Exposure to toxins and harmful factors (e.g. asbestos, allergies)

➢ Nutritional diseases Diet related, excessive or insufficient food consumption (e.g. scurvy, obesity, type 2 diabetes)

➢ Cancer Many causes (e.g. infections, genetics, environment)

● Collect and represent data to show the incidence, prevalence and mortality rates of non-infectious diseases, for example: ➢ Nutritional diseases

Many nutritional diseases result from lack of, imbalance or sometimes over consumption of certain nutrients. This can lead to kwashiorkor, a disease that causes fluid retention, anorexia, ulcerating skin and an enlarged liver. A lack of other nutrients can lead to a number of different diseases such as scurvy, rickets and coronary heart disease. Kwashiorkor ~ Kwashiorkor is a nutritional disorder caused by a severe protein deficiency found in regions where there is severe famine. It also occurs in cases of abuse, neglect or ‘fad’ diets.

Symptoms: Kwashiorkor causes the muscles become wasted and the person feels constantly tired. The liver becomes enlarged, the hair thins, teeth fall out and the skin develops dermatitis. The immune system is affected leading to more frequent and severe infections. Long term effects can show in lower physical and mental development. These symptoms are so broad because all cells require protein, and therefore all cells are affected and most major organ systems show symptoms Host Response: Reduced protein intake reduces plasma proteins, which impairs the body’s ability to maintain osmotic pressure with the osmotic imbalance in the gastrointestinal tract leading to fluid retention and problems with the lymphatic system. Prevalence: Globally Kwashiorkor is most prevalent in overpopulated regions, e.g. Africa, Central and South America and South Asia and is typically seen in young children (1-3 yrs old) In Australia, malnutrition is a serious problem and has been called the ‘silent epidemic’. Prevalence occurs in aged care facilities and isolated rural areas. Incidence and Mortality: In areas where Kwashiorkor is prevalent there is a relatively high case mortality rate. In Australia kwashiorkor has low incidence and very low mortality rate.

➢ Diseases caused by environmental exposure Asbestosis ~ Asbestosis is a chronic respiratory disease caused by inhaling asbestos fibres and is an important factor in many cases of occupational cancer. Cause: Asbestosis usually results from breathing in microscopic asbestos fibres over a long time (e.g. by people working with asbestos in mines or making products containing asbestosis). The fibers are inhaled in dust leading to the formation of scar lung tissue (e.g. around bronchioles and alveolar ducts). Symptoms: Symptoms of asbestosis usually appear a long time after exposure to the fibres (10-20 yrs). First symptoms include tightness in the chest, shortness of breath (due to the reduced lung volume), coughing, wheezing, chest pain etc. This can lead to respiratory failure. Complications caused by asbestosis can lead to lung cancer and pulmonary heart disease. Asbestos fibres can cause a pleural mass to grow on either layer and spread to the other later developing into a sheath like mass around the lung causing pleural mesothelioma.

Host Response: Asbestos fibres activate the immune system in the lung and the inflammatory response. Macrophages engulf the asbestos fibres and accumulate in bronchioles and blood vessels stimulating fibrosis to deposit fibrous connective tissue in a process called fibrosis. Prevalence, Incidence and Mortality Rate: The Australian Bureau of Statistics provides data on the leading causes of death and the Australian Mesothelioma Registry (AMR) provides data about the incidence and prevalence of mesotheliomas. The Cancer Institute of NSW provides cancer statistics (cancer incidence, mortality and survival with data on cancer screening and clinical trials). Historically asbestosis has been a male dominated disease mainly due to occupational exposure. The Australian Mesothelioma Registry reported in their 2015 Annual Report that there were 650 people (505 males and 145 females) newly diagnosed with mesothelioma in 2015 compared to 732 people (593 males and 139 females) in 2014 and that Australia has the highest global incidence of malignant mesothelioma. Epidemiology Inquiry question: Why are epidemiological studies used?

● Analyse patterns of non-infectious diseases in populations, including their incidence and prevalence, including but not limited to: ➢ Nutritional diseases

Obesity Cause:

- High calorie diets - Sedentary lifestyle

Global Patterns:

- In 2016, 650 million adults were obese (13% of adults over 18) - 41 million children over 5 were overweight or obese - 340 million children and adolescents 5-19 were overweight or obese - Obesity has tripled worldwide since 1975 - At least 2.8 million die per year as a result of being overweight or obesity - Prevalence of obesity is highest in the americas (26%) and lowest in south east

Asia (3%) - In the Americas, Europe, and Eastern Mediterranean, roughly 25% of all women

are obese (in all regions, women are more likely to be obese than men) Contributing Factors:

- ‘Nutritional transition’ is a term used to define a set of hanging risk factors that a country may face as they develop

- Changes in diet: as countries become more developed, populations usually begin to purchase more processed food, rather than grow or buy fresh ingredients, leading to diets with more fat and lower complex carbohydrates

- Changes to lifestyle: as food production technologies develop, populations undergo changes to their work and leisure activities, usually resulting in more sedentary lifestyles

- The effects of these factors can be seen in India and China among urban residents and high income rural residents

➢ Diseases caused by environmental exposure

Cancer Cause:

- Physical, chemical, and biological carcinogens, as well as genetic factors, resulting in transformation of normal cells into abnormal tumour cells.

Global Patterns:

- Second leading cause of death globally (8.8 million deaths in 2015) - 70% of cancer deaths occur in low and middle income countries - Tobacco use is responsible for approximatrly 22% of cancer deaths - Most fatal cancers globally: lung, liver, colorectal, stomach, breast

● Investigate the treatment/management, and possible future directions for further

research, of a non-infectious disease using an example from one of the non-infectious diseases categories listed above

Type 2 diabetes Type 2 diabetes is a condition whereby the body becomes resistant to the effects of insulin, and gradually becomes unable to produce insulin effectively. The result of this is that individuals are unable to regulate their blood glucose levels effectively. It may also lead to medical problems such as cardiovascular disease, and nerve and kidney damage. Prevention:

- Maintaining a normal weight - Eating a healthy and varied diet - Exercising regularly

Treatment and management: - Lifestyle changes ~

➢ Eating well: helps to manage levels of blood glucose

➢ Exercising: lowers blood pressure and helps insulin to work effectively, reducing the risk of heart disease. Physical activity also helps to lower blood sugar levels, as glucose is being used by cells to enact aerobic respiration

- Monitoring ~ testing blood glucose levels regularly allows patients to effectively manage their treatment, ensuring that these levels stay within a healthy range.

- Treatment ~ ➢ A medication called metformin which decreases the amount of glucose

produced in the liver, as well as increasing insulin sensitivity in many tissues.

➢ As type 2 diabetes progresses, and the pancreas continues to become less effective at producing insulin, patients may also be required to take insulin injections. Insulin signals to cells to take up glucose, and therefore helps to lower blood glucose levels in diabetics.

➢ Bariatric surgery may also help in reducing its effects (reducing the size of the stomach by removing a portion of it). This may potentially reset the metabolism, essentially curing diabetes.

Future directions for research: - An increased understanding of the factors contributing to the development of

type 2 diabetes would help in designing better prevention measures and create effective treatment and management strategies

- Understanding genetic risks and analysing genomes to identify genes which may place an individual at risk of developing the disease. This would allow the tailoring of preemptive, personalised medicine.

- Type 2 diabetes is commonly treated by taking insulin shots. Synthetic production of insulin is an important area of research, particularly in terms of how to make this process faster, more efficient, and less expensive.

- Another treatment option is whole organ pancreas transplant - Instead of inserting an entirely new organs into patients, islet cell transplant may

be an option for diabetes. As islet cells are dysfunctional in diabetic patients, unable to properly produce insulin.

● Evaluate the method used in an example of an epidemiological study

Types of epidemiological studies: Descriptive ~ A study of the patterns of distribution within and across populations Analytical ~ A study examining known associations, or testing specific hypotheses. Experimental ~ A study which measures the effectiveness of interventions, such as clinical or community trials of new treatments.

Analytical Study ‘Smoking and Carcinoma of the Lung’: Initial hypothesis ~ That the significant increase in deaths attributed to cancer of the lung in England and Wales between 1922 - 1947 was a result of either: atmospheric pollution from car exhaust fumes or the smoking of tobacco, both of which had become more prevalent in the 50 years prior to the study. Methodology ~ 20 London hospitals in the north west area were asked to participate in the study. Whenever a patient was admitted to said hospitals presenting with carcinoma of the lung, a researcher would visit the hospital and interview the patient. Four designated researchers conducted all interviews using a set questionnaire. For each lung-carcinoma patient interviewed, an individual of the same sex and age affected by a cancer other than carcinoma was interviewed, using the same questionnaire, in the same hospital at the same time. Evaluation ~ The questionnaire used attempted to thoroughly investigate the history of patients, and collected data not only on smoking habits but on other lifestyle factors. Reliability may have been improved by taking data from hospitals outside of the immediate London area, so that environmental variables could be more sufficiently taken into account. In addition, a study monitoring individuals across a larger period of their lives, rather than only after they had developed a disease, may have provided a more statistically sound conclusion.

● Evaluate, using examples, the benefits of engaging in an epidemiological study Epidemiology is an interdisciplinary field which combines the expertise of epidemiologists, laboratory technicians, statisticians, doctors, and public health professionals. This means that studies are often comprehensive and wide reaching in their implications and applications. The use of a thorough, rigorous methodology to trace the origins of disease ensures that findings remain objective, and may at times uncover unexpected findings. E.g. when Doll and Hill first began studying causes of lung cancer, they believed that it was mostly due to either car fumes of new material tarmac. However, they discovered that tobacco smoking was the only significant common factor between patients with carcinoma. Epidemiology is concerned with disease surveillance, investigating outbreaks, and conducting observational studies which help to identify risk factors in disease. By identifying the causes of disease, epidemiology provides public health professionals information so that they can strategise and plan programs and campaigns to help

prevent disease. E.g. the Australian Cancer Council is currently undertaking the ABC study, with an outlook towards designing better preventative measures. By determining the levels of disease impact at national, regional, and global levels health and inequality. This displays how epidemiology makes an important link between research and public health policy, and the overall benefits of a community based approach to disease treatment and health. Additionally, identification of the causes of disease allows scientists to better understand where to direct research efforts. Prevention Inquiry question: How can non-infectious diseases be prevented?

● Use secondary sources to evaluate the effectiveness of current disease-prevention methods and develop strategies for the prevention of a non-infectious disease, including but not limited to: ➢ Educational programs and campaigns

Educational Campaign: Slip! Slop! Slap! Disease: Skin Cancer Methods:

- Television advertisements and community service announcements, including a catchy jingle

- Aimed to raise awareness of skin cancer and the risks posed by ultraviolet light exposure from the sun

- A cartoon seagull, Sid, appeared in the campaign, encouraging people to ‘slip’ on sun protective clothing, ‘slap’ on sunscreen and ‘slap’ on a hat

- In 2009, the SunSmart campaign added two more sun protection measures - ‘seek’ shade and ‘slide’ on sunglasses

- Since the success of the program in the 1980s, SunSmart have incorporated further strategies to their campaign, including: ➢ Implementation of legislative changes ➢ Development of educational resources for schools and workplaces ➢ Sponsorship of sporting events

Effectiveness:

- One of the most successful health campaigns in Australia’s history - Believed to have played a key role in the shift of Australian attitudes towards sun

safety - Incidence of two most common skin cancers has decreased since the

introduction of the campaign - Incidence of most lethal skin cancer (melanoma) has, however, increased - Program has been shown to be particularly effective amongst younger people

- For people aged 20-24, the rate of melanoma has fallen from 25 per 100 000 to 14 per 100 000 between 1996 and 2010

- Estimated to have prevented more than 43 000 skin cancers in Victoria (where the campaign was started) between 1988 and 2011

- The SunSmart programs are considered to be extremely cost effective, saving the Victorian government $2.20 for every dollar spent in the Victorian public health program

➢ Genetic engineering

Many non-infectious diseases are the result of mutations to our genetic material. If we are able to trace the causes of disease to specific changes in our DNA sequences, this opens up the possibility of curing diseases using genetic engineering. Genetic engineering techniques allow us to make changes to the genetic code, thus allowing us to edit sequencing causing non-infectious disease.

● Gene therapy: The correction of genetic disorders by introducing a normal, functioning gene into cells. This is achieved by inserting corrected gene sequences into a cell where a defect has occurred. Techniques used to inject new genetic material include the insertion of viral vectors, use of a gene gun, and inorganic nanoparticles. This can be used to treat:

- Severe combined immune deficiency - Haemophilia - Parkinson’s disease

● CRISPR: A gene editing system by which point mutations may be accurately into genomes. CRISPR may be used to improve gene therapies by making point mutations (up to 20bp) to dysfunctional cells. Such changes will alter the genomes of all edited cells, as well as any cells which grow from them, resulting in lasting somatic cell edit.

● Embryo screening or editing: Increased access and decreased costs of whole genome sequencing opens up the possibility of screening embryos for genetic disorders. This may be particularly beneficial for couples who carry known genes for disease. Screening allows selection of embryos only without genetic defects for implantation. Editing technologies, especially at the early embryo stage, open up the possibility that whole organism changes may be made to the offspring. Steps involved in preimplantation screening:

1. A few cells are collected from the embryos (test tube baby) 2. The DNA of each removed cell is screened to detect whether they are

carrying any genetic or chromosomal abnormalities 3. The embryos not carrying abnormalities are put into the womb 4. Extra embryos stored and frozen for later use

Technologies and Disorders Inquiry question: How can technologies be used to assist people who experience disorders?

● Explain a range of causes of disorders by investigating the structures and functions of the relevant organs, for example: ➢ Hearing loss

Sound is the vibration of particles and occur as compression waves. The pitch relates to the number of waves per second and the amplitude relates to the volume. The ear is composed of three sections:

1. The outer ear (pinna and ear canal) 2. The middle ear (ossicles - hammer, anvil and stirrup - and ear drum) 3. The inner ear (the cochlea, and auditory nerve and the brain)

When sound enters the ear in the form of waves, the eardrum vibrates. This vibration movement causes the bones of the middle ear, the ossicles, to move in a chain like fashion. This movement ‘knocks’ on a membrane window of the cochlea. The cochlea is filled with fluid, which moves in response to this knock. Hair cells lining the cochlea are bent in response to the fluid vibrations, which creates an electrical impulse to be sent along the auditory nerve to the brain.

● Conductive hearing loss: Occurs when there is damage to the outer or middle ear, resulting in ineffective sound transfer. In these cases, the cochlear may still be functional, but does not receive sufficient signal to create an auditory impulse. Conductive deafness may result from ear infections, otosclerosis (abnormal bone growth in the middle ear), or perforation of the eardrum.

● Sensorineural hearing loss: Occurs when there is damage to the inner ear. Sound may arrive at the cochlear, but it is not properly passed on to the auditory nerve, or the auditory nerve itself may be damaged. Damage may be congenital (hearing loss present at birth), as a result of genetic factors or disease, or acquired due to a wide range of factors, such as age, noise exposure, physical trauma, or diseases such as meningitis.

● Mixed hearing loss: Has both conductive and sensorineural hearing loss. ● Auditory processing disorders: involve problems in the brain that prevent

sounds being processed correctly The eardrum (tympanic membrane) can be burst (or perforated) by injuries to the ear, or by pressure building up in the middle ear. A burst eardrum can be caused by an object entering the ear canal and puncturing the eardrum. Vibrations from a very loud noise can burst the eardrum. Middle-ear infections and changes in atmospheric pressure, e.g. when scuba diving or flying in an aeroplane, can cause pressure to build up inside the middle ear, which can also burst the eardrum. It is important in these cases to equalise the pressure in the ears to avoid damage to the eardrum.

➢ Visual disorders Light enters the eye firstly through the cornea, a clear, curved ‘window’ on the front of the eye. The cornea refracts light through the pupil, an opening at the front of the eye, the width of which is controlled by the movement of the iris. Pupils are able to dilate and contract, the shape of the iris changing how much light enters the eye. Light then passes through the lens, a curved, flexible structure which focuses light by shortening or lengthening its width. The globe of the eyeball is filled with vitreous gel, a dense transparent substance that gives the eye its spherical shape whilst still allowing light to be transmitted to the back of the eye. Light rays come to a focal point, where the image is focused at the retina in the back of the eye. The retina acts like a kind of camera and is composed of two types of cells: rods and cones. These cells are excited by different wavelengths of light. As light hits the retina, light energy is converted into electrical impulses by the rods and cones, which sends the messages onto the optical nerve, and through to the brain for processing.

As a complex organ, there are a number of disorders which may contribute to malfunction of the eye.

● Refractive errors: Occur when the eye does not focus light properly, due to incorrect shaping of the cornea.

● Myopia: Nearsightedness, occurs when the cornea is too curved or the eyeball is too long, resulting in light refracted at an angle which places the focal plane in front of the retina. In this case, objects far away are blurry.

● Hyperopia: Farsightedness, occurs when the cornea is too flat or the eyeball is too short, resulting in light being focused beyond the retina. In this case, objects close up are blurry.

● Astigmatism: A disorder where vision is blurred at all distances, as a result of

misshapen cornea where curvature is not uniform in all directions. ● Other prevalent disorders include:

➢ Glaucoma: Blindness due to a build up of pressure in the eye, causing optic nerve damage.

➢ Cataracts: Clouded areas in the lens, causing blurry or tinted vision

➢ Loss of kidney function Kidneys are the body’s cleaners, processing blood to filter out waste products, and balance salt and water levels. Waste products are collected as urine, which moves from the kidneys to the bladder through the ureters, then out of the body through the urethra. Blood enters the kidney from the renal artery, and leaves via the renal vein. The main areas of the kidney are the cortex (outermost layer of the kidney), medulla (petal like inner structures), and pelvis (drainage area at the center of kidney, connected to the ureter).

Filtering is performed by microscopic structures called nephrons, situated across the cortex and the medulla. Every kidney has about a million nephrons, each performing the job of filtration. Capillaries are wound around the nephron structures, providing an interface across which exchange of nutrients may occur. When blood first enters the kidneys, the capillaries are squeezed into a very tightly wound structure called a glomerulus. This structure is so compact that all fluid in the blood (everything but red blood cells) is squeezed out, into the bowman's capsule. In the proximal convoluted tubule, essential molecules such as water, glucose, salts and nutrients are transferred back into the capillary. The rest of the nephron structure performs a balancing function, regulating the return of salts back into the blood in response to certain bodily requirements. Hormones may also act on the nephron, increasing permeability to certain substances to promote their reabsorption into the blood. All wastes, excess substances and fluids are then drained into the collecting duct, which leads to the renal pelvis to eventually be drained out of the kidney and the body.

What occurs at: Glomerulus ~ it is a ball of capillaries where components of the blood are forced into the bowman's capsule (urea, water, salts, glucose, amino acids, vitamins and minerals). Bowman’s Capsule ~ first part of the nephron where filtrate from the glomerulus moves in. Proximal Tubule ~ Glucose, some salts, amino acids, vitamins and minerals are pushed back into the blood by active transport. Loop of Henle ~ Active transport of salt back into the blood (causing a salty environment) and blood because of osmosis. Distal Tubule and Collecting Duct ~ some reabsorption will occur at the distal tubule of urea, some salts and water. Most is collected in the collecting duct and moved back into the ureter. Kidney failure occurs when the kidneys are no longer able to remove waste from your blood and control the level of fluid in your body. Some causes include polycystic kidney disease (causes cysts to form in kidney), diabetes and high blood pressure. These cause symptoms like nausea, loss of appetite and urine colour change. If kidney failure remains untreated it will result in blood toxicity leading to death. Acute kidney failure = occurs suddenly Chronic kidney failure = develops slowly over time

● Investigate technologies that are used to assist with the effects of a disorder, including but not limited to: ➢ Hearing loss: cochlear implants, bone conduction implants, hearing aids

Hearing aids: Hearing aids are electronic devices that can amplify sounds entering the external ear and are worn behind the ear or in the ear canal. They have a microphone to detect and convert sound into electrical signals, an amplifier to strengthen these signals, a receiver to convert the signals back to sound, and a speaker to direct the

sound into the external ear. Hearing aids rely on the natural functions of the ear to perceive the sound and to detect the larger vibrations. Benefits of hearing aids: amplifies sound, enables hearing, amplifies certain frequencies only (ones you can't hear - high frequencies) Limitations of hearing aids: lack of clarity, hard to distinguish specific voices in a crowd // lots of noise, only work with people who can partially hear - not deaf Bone conduction implants: People with outer or middle ear problems that block or restrict the flow of sound waves can be helped to hear with bone conduction implants. An external sound processor is attached either magnetically or directly to a small titanium implant that is surgically placed in the bone behind the ear. The sound processor detects and converts sound into vibrations that are transferred directly through bone to the cochlea. Hair cells within the cochlea convert these vibrations into nerve impulses to be sent to the brain, so that the person can hear. People with hearing loss can trial bone conduction treatment prior to surgery, by wearing the sound processor and external vibrator on a headband. Cochlear implants: Cochlear implants (‘bionic ears’) are used to treat profoundly deaf people with missing or damaged hair cells in the cochlea. Worn externally behind the ear is a speech processor that detects sound and converts it into digital code. This digital code is transmitted to an implant, just under the skin. The implant converts the digital code into electrical impulses and sends them along electrodes into the cochlea. The impulses directly stimulate the cochlear (auditory) nerve. The signals are recognised by the brain as sound, allowing the person to hear. Cochlear implants work best when implanted before the age of 5 years. They do not fully reproduce the sounds experienced by someone with full hearing and do not work if the auditory nerve is damaged. Once fitted, the patient has to be trained to interpret the sounds they ‘hear’ for the first time with the implant. Cochlear implants are very expensive due to production costs, the need to surgically implant the electrodes and ongoing costs to maintain the external parts. However, for people with significant hearing loss, cochlear implants facilitate hearing to occur. This is particularly helpful in allowing young children with hearing loss to learn spoken language.

➢ Visual disorders: spectacles, laser surgery The way light refracts (bends) as it travels through the cornea and lens of the eye determines whether vision is clear. Many people have visual disorders due to refractive errors that cause them to experience blurry vision. Effective treatment is usually achieved for most people with these disorders through using glasses, contact lenses or laser surgery.

Several common visual disorders that occur due to refractive errors include: - Myopia (short sightedness // nearsightedness) ~ Blurry vision is experienced

for objects that are distant. This is caused by the light being focused in front of the retina. The cause of the disorder could be the shape of the eye is too long or the cornea is too curved.

- Hyperopia (long sightedness // farsightedness) ~ Blurry vision is experienced for objects that are close. This is caused by the light being focused behind the retina. The cause of the disorder could be the shape of the eye is too short or the cornea is too flat.

- Astigmatism ~ is a visual disorder that can be caused by an irregular shaped cornea or irregular shaped lens. The light is focused on multiple points in the retina causing double or blurry vision.

- Presbyopia ~ is an age related visual disorder involving a refractive error that causes blurry vision. It typically causes light to focus behind the retina of the eye, in a similar manner to hyperopia. For near vision, the ciliary muscles contract and the lens becomes rounder. For distant objects, the ciliary muscles relax and the lens becomes flatter. As people age, the ciliary muscles don’t work as well as the lens is less elastic and makes it hard to focus and can no longer accommodate. Accommodation refers to the ability of the lens to change shape to focus on near and far objects.

Convex vs Concave Lens Convex lenses correct hyperopia as it brings the focal point forward so the focus is now on the retina and not behind the eye. Concave lenses correct myopia as it brings the focal point back so the focal point is no longer in front of the retina. Glasses vs Contact Lens Refractive errors that cause vision disorders can be effectively corrected using glasses and/or contact lenses. Presbyopia often requires correction using a combination of lenses and so bifocal (or multifocal) lenses are typically used. For people with astigmatism, the curvature of the lenses used in their glasses or contacts are varied to counteract the asymmetry in the cornea or lens of their affected eye(s).

Advantages Disadvantages

Glasses - Take off easy - Less infections // ulcers

(dirt // sand get caught underneath)

- Distance between eye and lens creates distortion

- Less peripheral vision - Discomfort → sensitivity in eye

Contact Lenses

- Don’t fog up - Can’t always put them in ~ eye sensitivity

Eye Surgery

1. Local anaesthetic is applied using eye drops 2. The eyelid is held open by a lid separating device 3. An ultrathin flap is made in the top layers of the cornea using a laser 4. The corneal flap is temporarily lifted back 5. A cool laser is used to remove corneal tissue to correct the shape of the cornea 6. The corneal flap is returned to its correct position.

Risks could include dry eyes, sensitivity to light and blurred vision. Cataracts: Cataracts are regions of cloudiness in the clear lens of the eye. They cause vision to become blurry and change the way colours are seen. They commonly develop as people age. Some people have larger cataracts that cause more severe visual disorders, while others only have such small cataracts that they don’t even notice them. Fred Hollows → did a bunch of cataract surgery in third world countries. Set up foundation before he died.

➢ Loss of kidney function: dialysis The preferred treatment in most cases of kidney failure is a kidney transplant. However, transplant organs need to be carefully matched to recipients to prevent host immune responses destroying the introduced organ. People with kidney failure often have to wait a number of years before a transplant becomes a treatment option. Kidney dialysis is a life prolonging treatment for people with kidney failure. The most common form of kidney dialysis is haemodialysis. Hemodialysis needs to be done at least three times per week, with each session lasting for four to five hours. Haemodialysis involves the patient’s blood being pumped through a dialyser. Within the dialyser, the blood passes through many tiny tubes made of semi-permeable membranes. These tubes are constantly surrounded by a special fluid called dialysate. The semipermeable membrane allows small substances, such as salts, water and urea, to pass by diffusion between the blood and dialysate, but does not allow large substances to pass, such as blood cells. The dialyser allows the blood to be ‘cleaned’ and helps to regulate the homeostasis of water and ion concentrations.

● Evaluate the effectiveness of a technology that is used to manage and assist with the effects of a disorder

Kidney Failure

Technology Haemodialysis

Description Haemodialysis is a type of dialysis in which waste is filtered outside of the body, using a dialysis machine. An A-V fistula is made across the patient’s veins, from which blood is drawn. Blood is circulated through a dialyser, through a series of semipermeable membranes, allowing for toxins to be filtered from the blood by passive transport. Dialysers have:

- A compartment for blood - A compartment for dialysate fluid (which is specifically calanced in order to allow excess

wastes to pass into it by passive transport along the concentration gradient) - A semipermeable membrane separating the two liquids

Effectiveness (positive effects)

- Allows for removal of metabolic wastes (urea) when kidneys no longer function (a buildup of urea may lead to seizures and ultimately death)

- Provides a long term solution (people are able to be treated using dialysis for many years), and gives patients time when waiting for kidney transplants

Effectiveness (negative effects)

- Works only by passive, not active transport, so not all wastes can be filtered, as they will only move into the dialysate until equilibrium is reached across the membrane

- Requires repeated, large blocks of time (4 hour sessions in hospital a few times a week), particularly in cases of advanced kidney failure, so can have a large impact on patient quality of life, both in terms of time consumption and the requirement to travel to hospital regularly

- Limits patient mobility and may be expensive - Dialysis requires that diet and fluid consumption are regulated, and often restricted - Dialysis does not cure kidney disease; it merely mitigates its effects, so if patients have

severe kidney failure, they may need dialysis for the rest of their lives, or until they have a kidney transplant.

Peritoneal Dialysis: Cleansing fluid is flown into the peritoneal cavity in the abdomen by a catheter (tube). Wastes are filtered into the cavity from the blood. The fluid with the waste products is then drawn from the abdomen and discarded. Peritoneal dialysis can be performed by yourself at home or whilst travelling, allowing for more flexibility in lifestyle and independence.