Module 8 Flashcards
Endotherms
Organisms that generate heat from their body metabolism, so their internal body temperature is independent of the ambient (external) temperature e.g Mammals.
Adaptations
Are characteristics that organisms possess that will increase their survival and reproductive chances in their environment.
What are the three different types of adaptations
Behavioural - the way an organism acts
Structural - the physical characteristics of the organism
Physiological - the way the organisms body functions
Transpiration
The evaporation of water in a plant through the stomata in a leaf.
Stomata
Any of the minute pores in the epidermis of the leaf or stem of a plant, forming a slit of variable width which allows movement of gases in and out of the intercellular spaces.
What is epidemiology?
The study of the distribution and determinants of health-related states or events (including disease) and the application of this study to the control of diseases and other health problems.
What is the difference between Correlation and Causation?
Correlation is the extent to which the change in two variables is related. Causation is when one variable changes as a direct result of the other. Two variables can have weak or strong correlation. Finding correlation between variables is a starting point for further research to find out if there is a causal relationship.
Explain why an epidemiological study is beneficial for society, providing specific examples.
Epidemiological studies allow better disease prevention, by assisting research into risk factors and strategies to prevent the disease, e.g. epidemiological data helped to show that cigarette smoking causes lung cancer, prompting changes to smoking laws and government campaigns to reduce smoking rates. Similarly, epidemiological studies of diabetes helped identify lifestyle risk factors (e.g. poor diet and lack of exercise). This prompted improved education, public health initiatives, and investment into research on diabetes.
Describe 2 examples of behavioural adaptations in endotherms which assist in maintaining body temperature/homeostasis.
The Macropus rufus - the red kangaroo - has the adaptation of changing of body position/alignment and movement to different areas to increase or decrease the amount of exposure of their surface area to the sunlight allowing them to thermoregulate. If the ambient temp is too high, these animals may change the position of their body to reduce the surface area exposed, seek shade, shelter in burrows or move into water to cool down. The red kangaroo does this during the hottest part of the day where it moves, seeking a position where it’s hind legs and tail are shaded by the rest of its body.
The grey plover - Pluvialis squatarola - migrates. Migrating organisms move to a different habitat that is within their tolerance range. The grey plover breeds in the northern hemisphere between May and August, then migrates to Australia during August and stays until April. This allows the birds to avoid the severe weather of winter.
Describe 2 examples of structural adaptations in endotherms which assist in maintaining body temperature/homeostasis.
The feathers of fairy penguins provide an insulating layer trapping a layer of air next to the skin to reduce the amount of heat lost. This layer of air can be altered depending on the ambient temperature. In cold conditions the feathers are lifted away from the skin, increasing the air layer and providing a greater degree of insulation. In hotter conditions the feathers lie flat against the skin, trapping a smaller amount of air.
The polar bear lives in a cold environment and is thus larger with a small surface area to volume ratio. This means that there is only a small surface area for heat loss compared to the volume, which allows the body to conserve heat.
Describe 2 examples of physiological adaptations in endotherms which assist in maintaining body temperature/homeostasis.
Blood flow can be increased or decreased at extremities to control temperature. The bilby has an extensive network of capillaries throughout the ear that aid in releasing heat to it’s surroundings.
Countercurrent exchange allows the warm blood in arteries to heat the cooler blood in the veins coming back from the cold extremities, before this blood is returned to the heart. This occurs in the feet of the platypus, so that the internal core temperature is not lowered by cool blood returning from limbs that have a large SA exposed to the cold water.
Describe mechanisms in Hydrophytes that allow water balance to be maintained.
Water Lily’s have high numbers of stomata on the upper surface of leaves which maximise water loss via transpiration as they have a plentiful supply of water. They also have leaves with very large surface areas which allows for maximum transpiration and photosynthesis.
Describe mechanisms in Mesophytes that allow water balance to be maintained.
The clover has the mechanism of opening and closing of stomata. When water is available the stomata remain open so the plant can maximise photosynthesis and promote the evaporation of any excess water. Mesophytes can conserve water if they need to by closing the stomata.
Describe mechanisms in Xerophyte
that allow water balance to be maintained.
Eucalyptus has few stomata protected within a localised depression and/or with stomatal hairs which helps maintain a humid microclimate. They also have thick waxy cuticles (outer layer) which ensure that all the epidermal cells are waterproof, preventing loss of water by evaporation from these surface cells. It also has leaves that hang vertically which minimises exposure to sunlight and water loss via evaporation.
Describe mechanisms in Xerophyte Succulent that allow water balance to be maintained.
The cactus has an Extensive root system (shallow roots spread out laterally to maximise absorption from desert soil) which Maximises its water absorption from the soil. As well as small and tough leaves which limit the surface area in proportion to volume → minimises water loss.
Describe the cause and effect of a genetic disease.
Cystic fibrosis is an inherited disease caused by mutations in a gene called the cystic fibrosis transmembrane conductance regulator (CFTR) gene on chromosome 7. The effect of this is:
- Thick mucus that clogs certain organs, such as the lungs, pancreas, and intestines.
- May cause malnutrition, poor growth, frequent respiratory infections, breathing problems, diabetes, liver failure, infertility and chronic lung disease as well as reduced life expectancy
Describe the cause and effect of a disease caused by environmental exposure.
Melanoma is caused by ultraviolet (UV) radiation from the sun and from tanning lamps and beds.
- It appears as a new spot or as a change in an existing mole or freckle, and can spread to other parts of the body.
- With time, the melanoma will spread to nearby lymph nodes, vessels and skin → then to distant lymph nodes, other areas of the skin and other organs → interfering with the correct functioning of the body and unless successfully treated will lead to death.
Describe the cause and effect of a nutritional disease.
Obesity is generally caused by eating too much and moving too little, which could be caused by a number of factors including psychological, cultural and economic factors. Its effects include:
- poorer mental health outcomes and reduced quality of life.
- Can lead to diabetes, heart disease, stroke, and some types of cancer.
- Increased blood pressure, atherosclerosis, gallbladder disease, stroke, type 2 diabetes, problems with weight bearing joints, increased risk of developing certain cancers.
- Reduced life expectancy
Describe the cause and effect of a type of cancer.
Lung cancer is caused by various factors including:
- Smoking
- Exposure to secondhand smoke - Previous radiation therapy
- Exposure to radon gas
- Exposure to asbestos and other carcinogens
- Family history of lung cancer
Its effects include:
- Shortness of breath if cancer grows to block the major airways
- Can also cause fluid to accumulate around the lungs, making it harder for the affected lung to expand fully when you inhale.
- The spread of cancerous cells can eventually lead to death.
Evaluate the effectiveness of an educational program or campaign to prevent disease.
The National Tobacco campaign was designed to prevent diseases including:
- chronic obstructive pulmonary disease
- acute myocardial infarction
- lung cancer
- stroke
Some of the strategies used to try to change the behaviour of individuals in the population included:
- Sponsorship bans at sporting events.
- Bans on smoking indoors (smoke free dining, banns in pubs, clubs, gaming venues and public transport) and in many outdoor public spaces.
- Legislation requiring plain paper packaging on all cigarette packets and storage in cupboards out of sight of consumers to reduce the appeal of tobacco products
- Increased excise of tobacco products to make them more expensive in a bid to discourage consumers from buying them.
- Graphic images in the media and on cigarette packets to highlights the dangers of cigarette smoking
- Use of slogans “Quit for life” “ICanQuit”
Effectiveness studies show that in the first 6 months of operation, the national tobacco campaign achieved a reduction of 1.4% in smoking prevalence and avoided 32 000 cases of chronic obstructive pulmonary disease, 11 000 cases of acute myocardial infarction, 10 000 cases of lung cancer and 2 500 cases of stroke. However, the campaign has targeted males more than females as the mortality rates due to smoking for females has increased since 1968, thus, it is not completely effective in targeting all groups of smokers.
Evaluate the effectiveness of genetic engineering to prevent disease.
An example of Genetic engineering being used to prevent a disease is the use of golden rice in developing countries, as the beta-carotene it contains allows the body to produce vitamin A, which reduces risk of blindness and strengthens the immune system by reducing vitamin A deficiency. It’s beneficial in that it reduces Vitamin A deficiency and thus reduces the risk of blindness, however, the vitamin A it provides may not be sufficient. There are also risks associated with its use including the fact that it could cross-breed with and contaminate wild rice.
Distinguish between the terms ‘treatment’ and ‘management’ when referring to non infectious disease.
Treatment of a disease will depend on the type of disease. Some non-Infectious diseases such as vitamin or mineral deficiency, simply require the correct amount of the vitamins/minerals to be included in the diet, whether in food or by supplementation. Other diseases, such as cancer, require more complex treatments to try and cure the individuals. Management refers to care and attention given to try and minimise the symptoms of a non-infectious disease.
Briefly describe how radiation works as a treatment option for melanoma.
Radiation - when cells are exposed to X-rays, normal cells can repair their DNA more easily than cancer cells can. X-rays damage the DNA of cancer cells and kill them. Care must be taken in directing the radiation to specific cells that are intended for destruction. Can be administered externally or by placing a radioactive source in the body near the cancer cells.
Briefly describe how chemotherapy works as a treatment option for melanoma.
Chemotherapy - drugs slow the growth of cancer cells, but they have not been particularly effective in treating melanoma, and so are not used to treat this form of cancer as much as in other cancers.
Briefly describe how immunotherapy works as a treatment option for melanoma.
Immunotherapy - treatments effectively cause the body’s own immune system to fight the melanoma. Two approaches are in the early stages of development and use. One of the approaches is to use drugs called ‘checkpoint inhibitors’ that cause the immune system to recognise and destroy melanoma cells. The other approach is to use vaccinations as a method of treatment rather than prevention. An antigen is produced using the melanoma cells, and when injected allows the immune system to more easily identify and destroy the melanoma cells.
Briefly describe how targeted therapies work as a treatment option for melanoma.
Targeted therapies - involve the use of drugs that affect the molecules that control the growth of the tumour cells, which effectively stops the growth and spread of the tumour to other organs.
Explain why future research is required to further develop the Targeted therapies for melanoma
The use of targeted therapies is based on different types of mutations that cause uncontrolled cell division that occurs in melanoma. Drugs have been developed to interrupt these specific pathways. Scientists are aware that numerous other mutations are yet to be identified, and so research is continuing in order to identify these. Once these mutations have been identified, further drugs will be developed to interrupt many more of these pathways.
How does a descriptive epidemiological study work?
- Data including information about age, sex, diet, occupation, drinking habits, location of work and home and places visited are collected from diseased individuals and commonalities are determined in order to find a positive cause.
- Hypotheses proposed about disease cause
- Provides information about the patterns of a disease including the frequency of the disease, which section of the population is affected (age, gender, socioeconomic status etc) the geographical location and whether there was a particular time period in which individuals were affected.
How does an analytical epidemiological study work?
- Morbidity and mortality are used
- Case control studies and cohort studies are two types of analytical studies that can be used
- Provides data about the incidence and prevalence
How does an Intervention study work?
Used to test the effectiveness of a new drug. People suffering from a disease/condition are observed for a set period of time. Participants randomly placed into 2 groups. One group receives a trial drug, other receives a placebo. Effects of medication are recorded and statistically analysed to determine effectiveness.
- Provides data about the effectiveness of a treatment
Distinguish between case-control studies and cohort studies.
Case control: Compare people with the disease to people without and look for differences in exposure to the possible cause of the disease. Age, sex, diet, location, lifestyle etc are collected from both groups
Cohort studies: involve studying two or more similar groups of people who are free of the disease. They differ in their exposure to the potential cause of the disease (one exposed and one not). Groups are followed over a long period of time.
What are random errors in epidemiological studies and how can they be reduced?
Random errors unpredictable variations in the data and have an inconsistent effect on measurement within a study. They make the study less precise but do not shift the results of the study in a particular direction. The effects of Random error can usually be corrected using statistics.
Describe and give an example of Selection bias
Selection bias is bias in selecting subjects to include in the study. In any study, the subject must be representative of the population that is to be studied. A number of factors in the selection process can cause bias, so that the sample studied is not representative of the population. An example of selection bias is sampling bias, in which the way the subjects are chosen or where they are chosen from does not lead to a sample that represents the population that is to be studied.
Describe and give an example of Information bias
Information bias involves errors in taking measurements or recording information. Inaccurate or incomplete measurements and observations will result in information bias if the inaccuracy affects each Study Group differently. An example of information bias is misclassification bias in which some of the subjects are already suffering from the condition and are undiagnosed at the start of the study.
Describe and give an example of confounding factors
A confounding factor is a type of systematic error that occurs when an unrecognised factor may be affecting the result of a study and leading to bias. A particular factor may be attributed to have caused a disease, but another factor could also have contributed to the same disease. For example, asbestos workers and non asbestos workers were studied to find the occurrence of lung cancer in each group. A confounding factor that needed to be taken into account in this study is whether the study participants were smokers, as this Factor could also contribute to the development of lung cancer.
Evaluate the method used in an example of an epidemiological study.
Epidemiological study (observational cohort study) on the incidence of Type 2 Diabetes in the Pima Indian population which examined the role of physical activity in the development of Type 2 diabetes in the Pima Indian population.
Evaluation:
- The study size of 1728 individuals and the 13 year time period over which it occurred - large sample size and a long period of study, reducing the effect of sampling bias
- Non diabetic Pima Indians from the same designated areas and aged 15 to 59 were studied, the group’s varied in the amount of physical activity that was part of their daily life. - Satisfies requirement of 2+ similar groups of people who are free of the disease being studied and the major difference between the groups being the factor that is being studied
- The diagnosis of diabetes was made by scientifically approved testing at the first and each follow-up visit. This reduced the likelihood of measurement bias.
- Trained interviewers used a scientifically valid questionnaire to determine the activity levels of a participant, reducing both interviewer and measurement bias.
- mathematical models - participants’ physical activities were weighted for their intensity level, and the activity levels of each individual were then classified as either high or low.
- Scientifically tested models were used to analyse the results and determine the incidence rates in diabetes related to activity levels and BMI index.
- Data was excluded from the analysis if individuals were thought to have incorrectly reported activity levels, which reduced recall bias.
- The written report of the study was peer-reviewed before publication.
Explain how Spectacles/Contact lenses are used to assist with the effects of a myopia disorder.
To correct myopia a concave lens is used either as spectacles or contact lenses. Through the use of the concave lens, which diverges the light rays, the focal point hits the right spot on the retina. (Fovea)
Accomodation
The process by which the lens changes shape according to the distance of an object of which it is focusing on. Without accommodation the eye would not be able to change focus from distant to close objects. Accommodation is important because it allows the eye to form focused images on the retina from objects at a range of distances from the eye. When the eye is at rest, the shape of the lens is flattened, the suspensory ligaments are taut, the ciliary muscles are relaxed, the focus is on far objects, focal length is long and refractive power is low. At full accomodation, the lens is bulging and rounded, the suspensory ligaments are relaxed, the ciliary muscles are contracted, the focus is on near objects, focal length is short and refractive power is high.
What is the structure and function of the conjunctiva?
Transparent membrane that covers the sclera. Lubricates and nourishes the eye. An infection of the conjunctiva causes a highly contagious condition called conjunctivitis.
What is the structure and function of the cornea?
A very sensitive transparent dome-shaped casement that covers the front of the eye. Refracts light and allows it to be focused on the cells of the retina.
What is the structure and function of the sclera?
The tough outer coating of the eye made of fibrin connective tissue. It is known as the ‘white of the eye’. Protects the inner parts of the eye and helps to keep its shape.
What is the structure and function of the choroid?
Layer of blood vessels in between the retina and the sclera. Provides nutrients to the back of the eye.
What is the structure and function of the pupil?
The opening that is made by the iris. Allows light to pass through to the retina.
What is the structure and function of the retina?
O.5mm thick lining the back of the eye, composed of approximately 150 million light sensitive nerve cells called rods and cones,. Rods are more numerous than cones and are light sensitive to shades of black and white but not to colour. Cones are colour-receptive cells. Converts light into electrochemical message that is sent to the brain for interpretation.
What is the structure and function of the Iris?
The coloured part of the eye that opens and closes to determine how much light enters. Controlled by the iris sphincter muscles that relax and contract depending on the light intensity in the environment.
What is the structure and function of the Lens?
A transparent biconvex disc behind the iris. Helps to focus light onto the retina. Its shape is changed by the ciliary muscles that help to focus the light entering the eye.
