Module 8 Flashcards
1
Q
Endotherms
A
Organisms that generate heat from their body metabolism, so their internal body temperature is independent of the ambient (external) temperature e.g Mammals.
2
Q
Adaptations
A
Are characteristics that organisms possess that will increase their survival and reproductive chances in their environment.
3
Q
What are the three different types of adaptations
A
Behavioural - the way an organism acts
Structural - the physical characteristics of the organism
Physiological - the way the organisms body functions
4
Q
Transpiration
A
The evaporation of water in a plant through the stomata in a leaf.
5
Q
Stomata
A
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.
6
Q
What is epidemiology?
A
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.
7
Q
What is the difference between Correlation and Causation?
A
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.
8
Q
Explain why an epidemiological study is beneficial for society, providing specific examples.
A
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.
9
Q
Describe 2 examples of behavioural adaptations in endotherms which assist in maintaining body temperature/homeostasis.
A
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.
10
Q
Describe 2 examples of structural adaptations in endotherms which assist in maintaining body temperature/homeostasis.
A
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.
11
Q
Describe 2 examples of physiological adaptations in endotherms which assist in maintaining body temperature/homeostasis.
A
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.
12
Q
Describe mechanisms in Hydrophytes that allow water balance to be maintained.
A
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.
13
Q
Describe mechanisms in Mesophytes that allow water balance to be maintained.
A
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.
14
Q
Describe mechanisms in Xerophyte
that allow water balance to be maintained.
A
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.
15
Q
Describe mechanisms in Xerophyte Succulent that allow water balance to be maintained.
A
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.
16
Q
Describe the cause and effect of a genetic disease.
A
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
17
Q
Describe the cause and effect of a disease caused by environmental exposure.
A
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.
18
Q
Describe the cause and effect of a nutritional disease.
A
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
19
Q
Describe the cause and effect of a type of cancer.
A
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.
20
Q
Evaluate the effectiveness of an educational program or campaign to prevent disease.
A
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.
21
Q
Evaluate the effectiveness of genetic engineering to prevent disease.
A
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.
22
Q
Distinguish between the terms ‘treatment’ and ‘management’ when referring to non infectious disease.
A
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.
23
Q
Briefly describe how radiation works as a treatment option for melanoma.
A
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.
24
Q
Briefly describe how chemotherapy works as a treatment option for melanoma.
A
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.
25
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.
26
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.
27
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.
28
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.
29
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
30
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
31
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.
32
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.
33
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.
34
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.
35
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.
36
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.
37
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)
38
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.
39
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.
40
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.
41
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.
42
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.
43
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.
44
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.
45
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.
46
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.
47
What is the structure and function of the Aqueous humour?
A transparent fluid with a watery consistency that is found in between the cornea and the lens. Keeps the shape of the eye and provides nourishment to the cells in the front of the eye.
48
What is the structure and function of the Vitreous humour?
A transparent gelatinous fluid that is found between the lens and the retina. Provides support for the back of the eye so light transmission to the retina is clear and free of obstruction. The fluid is mostly water but contains some salts, glucose and white blood cells to help prevent infections of the eye.
49
What is the structure and function of the ciliary body?
Produces aqueous humour. Also contains the ciliary muscles which control the shape of the lens.
50
What is the structure and function of the optic nerve?
Group of nerve fibres that travel from the retina to the brain. Transmits electrical message from the retinal cells to the brain for interpretation and response.
51
Explain the cause of the visual disorder myopia
Myopia is a disorder in which close objects can be viewed with no difficulty due to accommodation by the lens. However, distant objects appear to be blurred due to the light rays being refracted in front of the retina.
It is most common in youth. It usually results from any of the following causes:
- The shape of the eyeball is too elongated.
- The lens is too rounded as it may not flatten enough when the ciliary muscles contract.
- The refractive power of the cornea may be inadequate.
52
How does the lens change to view distant objects?
Light reaches eye in parallel rays.
Lens is quite flat/elongated and at resting state. Ciliary muscles relax.
Low refractive power. This means that there is very little to low levels of refraction occurring.
53
How does the lens change to view close objects?
Light reaches eye as diverging rays.
Lens becomes convex, that is bulging out. This is due to the ciliary muscle contracting.
High refractive power. This means that there is a high level of refraction occurring.
54
Explain the cause of the visual disorder hyperopia.
Hyperopia is a disorder in which distant objects can be viewed easily. However close objects appear blurry, due to the light rays being refracted behind the retina. Most common during later stages in life due to the weakening of the ciliary muscles and the decreased flexibility of the lens. It usually results from any of the following causes:
- The shape of the eyeball is too rounded (too short from front to back).
- The lens is too flat due to the weakening of the ciliary muscles and/or the the loss of elasticity of the lens
- The refractive power of the cornea may be too great for the shape of the eye.
55
Explain overall how spectacles/contact lenses are used to assist with the effects of visual disorders.
Spectacles are frames that hold corrective lenses made of clear, hard plastic. Contact lenses are lenses that are shaped to fit the curvature of the eyeball and are worn directly in contact with the surface of the eye.
56
Explain how Spectacles/Contact lenses are used to assist with the effects of a hyperopia disorder.
To correct hyperopia a convex lens is used either as spectacles or contact lenses. Through the use of the convex lens, which converges the light rays, the focal point hits the right spot on the retina. (Fovea)]
57
Explain how Spectacles/Contact lenses are used to assist with the effects of older age on vision.
For most people in old age the eye is unable to accommodate to near or distant vision - it is fixed at that person’s viewing distance, therefore bifocal lenses are needed in their spectacles. In bifocal lenses:
the upper segment focuses for distant viewing and
the lower segment focuses for close viewing.
58
Explain how Refractive Laser Eye Surgery is used to assist with the effects of vision disorders.
Refractive laser eye surgery is used to permanently reshape the cornea so that it converges or diverges the light entering the eye enough to correct the condition.
During the surgery, a flap of the cornea is cut and lifted and a laser beam is used to reshape the rest of the cornea, after which the flap of tissue is then replaced.
There are two common types of laser eye surgery:
LASIK (Laser Assisted In Situ Keratomileusis)
PRK (photorefractive keratectomy)
59
Compare LASIK and PRK laser eye surgery.
Both:
For both PRK and LASIK, the excimer laser then sculpts the stromal layer of the cornea to correct your refractive error.
The main difference between PRK and LASIK is that:
- In LASIK surgery a thin, hinged flap is created on the cornea to access the treatment area, whereas,
- In PRK the cornea's entire epithelial (outer) layer is removed to expose the area and no flap is created.
60
Explain briefly how LASIK eye surgery assists in treating vision disorders.
LASIK, or "laser-assisted in situ keratomileusis," is the most commonly performed laser eye surgery to treat myopia (nearsightedness), hyperopia (farsightedness) and astigmatism.
Like other types of refractive surgery, the LASIK procedure reshapes the cornea to enable light entering the eye to be properly focused onto the retina for clearer vision.
In most cases, laser eye surgery is pain-free and completed within 15 minutes for both eyes. The results — improved vision without eyeglasses or contact lenses — can usually be seen in as little as 24 hours.
61
Explain how the LASIK eye surgery procedure works?
Preparation:
- Eye exam to ensure the eyes are healthy enough for the procedure. They will evaluate: the shape and thickness of the cornea; pupil size; refractive errors (myopia, hyperopia and astigmatism); as well as any other eye conditions.
- Moistness of the eyes will also be evaluated, and a precautionary treatment may be recommended to reduce the risk of developing dry eyes after LASIK.
- An automated instrument called a corneal topographer is used to measure the curvature of the front surface of the eye and create a "map" of your cornea.
Process:
- Mechanical surgical tool called a microkeratome used to create a thin, circular "flap" in the cornea.
- Hinged flap is folded back to access the underlying cornea (called the stroma).
- Some corneal tissue is removed using an excimer laser. This highly specialized laser uses a cool ultraviolet light beam to remove ("ablate") microscopic amounts of tissue from the cornea to reshape it so it more accurately focuses light on the retina for improved vision.
- For nearsighted people, the goal is to flatten the cornea; with farsighted people, a steeper cornea is desired.
- After the laser reshapes the cornea, the flap is then laid back in place, covering the area where the corneal tissue was removed. Then the cornea is allowed to heal naturally.
62
How does the eye work when light enters?
Light enters eye and passes through thin conjunctiva --> Light passes through cornea, which refracts (bends) the light --> Light passes through pupil --> Light passes through lens, which refracts (bends) light to focus it on the retina --> Retina detects and converts light impulses into electrical stimuli --> Optic nerve carries electrical impulses from retina to brain --> Brain interprets electrical impulses to create an image.
63
Explain why future research is required to further develop Immunotherapy for melanoma
There are currently only two immunotherapy drugs available for use and these are not successful on all patients with melanoma. Further research is required to develop a greater variety of immunotherapy drugs, so that the majority of patients can benefit from this form of treatment of melanoma.
64
Explain why future research is required to further develop Vaccines for melanoma
The use of vaccines is in it's very early stages. More research is required to further refine this process and make it consistently effective. Further research may also involve investigating the relationship between melanoma and other cancers.
65
Cataracts
A cataract is a clouding of the clear lens in the eye, which reduces the transmission of light through the lens, causing blurred vision of both near and far objects, and increased sensitivity to the glare of bright sunlight. The proteins which form the lens are normally very precisely layered and arranged, allowing the lens to be completely transparent. If this internal structure deteriorates and the proteins become damaged or disorganised, the lens itself starts to become cloudy or brownish, interfering with the transmission of light through the lens and back onto the retina.
66
What are the causes of cataracts?
- Age - the incidence of cataracts rises rapidly from the sixth decade (from the age of 50-60) and keeps rising until the end of life.
- Other significant risk factors include family predisposition, eye trauma, diabetes and a history of dehydration in children from severe diarrhoeal infection and fevers.
- Lesser risk factors include the use of some drugs, the presence of other eye conditions, particularly inflammation in the eye and sunlight exposure.
- Children and babies can have cataracts and sometimes be born blind from it. This is called congenital cataracts and is uncommon.
67
Can cataracts be prevented?
Because of the way the risk factors such as age and family predisposition determine the likelihood of getting cataract, it is not generally possible to prevent cataract. However, the prevention of diabetes, the avoidance of eye trauma, the treatment of inflammatory diseases, the reduction of the burden of diarrhoeal diseases in communities and the avoidance of unnecessary use of certain drugs will result in some reduction of the load of cataract blindness. There is no known effective medical treatment which can prevent cataract from developing or slow its progress once it appears. Access to screening and good quality specialist eye services is crucial for people with cataract to get appropriate and timely advice about management and the need for surgery.
68
How is cataract surgery used to assist with cataracts?
Cataract surgery or intraocular lens implantation involves replacing the cloudy lens with an artificial lens called an intraocular lens (IOL). The IOL is implanted during cataract surgery, after the cloudy crystalline lens (otherwise known as a cataract) has been removed. There are two types of cataract surgery:
1. Phacoemulsification, or phaco: a small incision is made on the side of the cornea, the clear, dome-shaped surface that covers the front of the eye.
A tiny probe is then inserted into the eye. This device emits ultrasound waves that soften and break up the lens so that it can be removed by suction.
2. Extracapsular surgery: a longer incision is made on the side of the cornea and the cloudy core of the lens is removed in one piece. The rest of the lens is then removed by suction.
NOTE: A small incision is desirable because it is safer, the technique is faster and it heals rapidly without stitches (sutures), allowing a rapid return of good vision and normal activities.
69
How is replacing the lens used to treat cataracts?
After the cataract (cloudy lens) has been removed, it often is replaced by an intraocular lens (IOL). The IOL is a clear, plastic lens that requires no care and becomes a permanent part of the eye. Light is focused clearly by the IOL onto the retina, improving vision. The patient will not feel or see the new lens.
Some people cannot have an IOL. They may have another eye disease or have problems during surgery. For these patients, a soft contact lens, or glasses that provide high magnification, may be suggested.
70
Outline the structure of the ear.
The ear can be divided into three parts leading up to the brain – the outer ear, middle ear and the inner ear.
The outer ear consists of the ear canal and eardrum. Sound travels down the ear canal, striking the eardrum and causing it to move or vibrate.
The middle ear is a space behind the eardrum that contains three small bones called ossicles. This chain of tiny bones is connected to the eardrum at one end and to an opening to the inner ear at the other end. Vibrations from the eardrum cause the ossicles to vibrate which, in turn, creates movement of the fluid in the inner ear.
Movement of the fluid in the inner ear, or cochlea, causes changes in tiny structures called hair cells. This movement of the hair cells sends electrical signals from the inner ear up the auditory nerve (also known as the hearing nerve) to the brain.
The brain then interprets these electrical signals as sound.
71
What is the structure and function of the pinna?
Fleshy external organ consisting of a flap of cartilage and skin. It collects sound and directs into the ear canal.
72
What is the structure and function of the tympanic membrane (eardrum)?
Thin membrane between the external ear and middle ear. Vibrates when sound waves reach it; transfers the vibration to the hammer. Kinetic energy from air vibrations in pinna are transferred to the tympanic membrane, causing it to vibrate with the same amplitude and frequency. The kinetic energy is transferred to the ossicles.
73
What is the structure and function of the Ear ossicles?
Three tiny bones located in the middle ear; hammer, anvil and stirrup. They magnify and transfer vibrations from the tympanic membrane to the oval window on the cochlea.
74
What is the structure and function of the Oval window?
Flexible membrane between the middle and inner ear. Transfers vibrations from the stirrup to the fluid in the cochlea.
75
What is the structure and function of the Round window?
Flexible membrane between the middle and inner ear. Equalises pressure in fluid filled inner ear when oval window vibrates.
76
What is the structure and function of the Cochlea?
Fluid filled spiral tube that contains the organ of corti. Detects different frequencies of sound - high pitched sounds are detected at the start of the cochlea and low pitch sounds at the end of the spiral. Sound vibrations are transmitted as pressure waves in the fluid, where they stimulate the Organ of corti. This contains hair cells which are the actual "sensory cells". When stimulated by a pressure wave, each hair cell sets off a nerve impulse.
77
What is the structure and function of the Organ of Corti?
The Organ of Corti is found along the length of the cochlea. It contains about 15 000 hair cells which are distributed along the basilar membrane in rows of four. Sound waves cause the basilar membrane to flex and different frequencies cause movement of the membrane at different locations. Consists of hair cells on the basilar membrane. Hair cells translate vibrations into electrochemical signals.
78
What is the structure and function of the Auditory nerve?
Consists of the axons of the hair cells and leads from the cochlea to the brain. Transfers the impulse from hair cells to the brain.
79
Describe the cause and effect of conductive hearing loss.
Causes:
- Blocked ear canal caused by excessive earwax
- Infection in the ear canal
- perforated ear drum
- Benign tumour
- Fluid in the middle ear
- Middle ear infection
- Damage to ear ossicles
- Abnormal bone growth
Effect:
- Can be resolved
- Inhibit movement of vibrations through the outer and middle ear
- Usually affects loudness of sound
80
Describe the cause and effect of sensorineural hearing loss.
Causes:
- Damage to hairs or nerve cells in the cochlea, affecting the transmission of electrical signals
- Severe cochlea damage
- Head trauma
- Infection
- Malformation of the inner ear
- Autoimmune inner ear diseas
Effect:
- Permanent
- Damage to the inner ear
- Prevents vibrations being transformed into electrical impulses to be sent to the brain for interpretation
- Affects loudness and clarity of sound
81
Describe the process of hearing.
1. Pinna collects sound waves which pass through ear canal.
2. Waves reach ear drum causing it to vibrate.
3. Vibrations then pass to the middle ear (ossicles).
4. Ossicles amplify the noise and pass it to the inner ear.
5. Vibrations pass through the fluid of cochlea, making tiny hairs move.
6. This causes electrical signals to travel through the auditory nerve, to your brain.
82
Describe how a hearing aid is used to assist with hearing disorders.
Hearing aids are used for people with damage to outer or middle ear (ruptured tympanic membrane or damaged ossicles). They are not completely deaf, they need some residual hearing because hearing aids only amplify sound. Once in place, person can greatly improve comprehension, speech and low frequency discrimination. Hearing aid is used to magnify sound vibrations to better enable their transmission to the middle ear and then the inner ear.
83
Describe how a Bone conduction implant is used to assist with hearing disorders.
Also known as Bone anchored hearing aids (BAHAs). It is for people with moderate hearing loss, conductive and mixed hearing loss or single-sided deafness (unilateral hearing loss). Vibrations are passed via the implant to the bone above the ear where the vibrations are directed through the bone to the cochlea, bypassing the malformed or damaged outer and middle ear. Vibrations sent directly to the inner ear (cochlea).
84
Describe how Cochlear implants are used to assist with hearing disorders.
It is treatment for people that are profoundly deaf with damage to the inner ear (damaged hair cells in the cochlea) or auditory nerve. Its for people who will no longer receive any benefit from hearing aids.
It has a microphone that detects the sound and transforms it into a vibration. Uses an external speech processor and transmitter coil. Internally, a receiver is attached to an electrode implanted in the cochlea. The microphone of the speech processor detects sound, which is converted into a digital signal that is sent to the transmitter, then to the receiver. The digital signals are converted to electrical signals which are then sent to the electrode array in the cochlea where the nerve endings are stimulated. These signals are then sent to the brain for processing.
85
Evaluate the use of hearing aids as treatment for hearing disorders.
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Advantages:
relatively cheap
no surgery required so no recovery time is required.
no side effects
may be used successfully at any age
modern day hearing aids are programmable
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Disadvantages:
background noise is amplified
will not restore normal hearing
Quality is dependent on residual hearing
does not assist person if there is damage to the inner ear (cochlea), auditory nerve or auditory centre of the brain.
need to adjust to sound level
distance is limited to less than 3 m and most effective over 1m
may still depend on lip reading
amplification of sound can lead to distortion
if 2 hearing aids are worn you can get feedback interference
86
Evaluate the use of a bone conduction implant as treatment for hearing disorders.
Advantages:
Suited to people who are physically unable to wear conventional hearing aids
great for people with single-sided deafness
great for people with chronic ear infections
has an almost 100% satisfaction rate
shown to give significantly better hearing for voice
Disadvantages:
Implantation depends on the skin and bone condition of the patient
Local infection following the operation
Loss of the osseointegrated fixture (integration of implant in the bone) as a result of trauma
Chronic pain (very rare)
Expensive
87
Evaluate the use of a Cochlear Implant as treatment for hearing disorders.
Advantages:
Provides hearing to profoundly deaf people and can restore hearing after injury.
Is now MRI friendly so people with underlying disorders can still have access to this technology.
Electrodes designed to stimulate nerve cells to hear frequencies associated with speech (250 - 8000 Hz) so they can be involved in oral communication.
Disadvantages:
requires surgery to place electrode in the inner ear
surgery is expensive
there are postoperative side effects such as infection or facial nerve damage
need to learn to interpret sounds
programming needs to be adjusted for different situations eg: speaking on phone, in a classroom, dining with friends
background noise is amplified
It is not inconspicuous.
If battery goes flat, appliance will not work.
Cochlear implant sounds are different from normal hearing (electronic type of sound). Cannot hear all ranges out of the speech range that the electrodes are designed for.
Cannot be used if auditory nerve is damaged.
88
Adaptations of one animal in a hot/dry climate.
Macropus rufus utilise several adaptations to survive in a hot, dry climate. An example of a behavioural adaptation is that the animal will seek shade during the hottest part of the day and sit in a position where its hind legs and tail are shaded by the rest of the
body – they are positioned at right angles to the body, with the tail pointing forward, to reduce the large surface area exposed to the sun. The red kangaroo also uses vasodilation (physiological adaptation) to increase the amount of heat lost to the surroundings.
89
Glomerulus
A ball of capillaries within the Bowman’s capsule that acts as an ‘ultra’ filter.
90
Bowman’s Capsule
A cuplike sac that encloses the glomerulus; functions to carry out the first step in filtration of blood.
91
Proximal and Distal Convoluted tubules and Loop of Henle.
Play a role in the reabsorption of substances.
92
Collecting Tubule/Duct
Opens into the pelvis of the kidney. They transport urine and absorb water.
93
How does Haemodialysis assist with the effects of kidney disorders. (Draw diagram to support)
Some weeks/months before this dialysis the doctor will prepare a vascular access. A machine called a dialyzer will clean your blood outside your body, it mimics the nephron. It cleans your blood, clean blood is then returned to your body. Because the concentration of metabolic wastes is higher in the blood than in the dialysate, the wastes move by diffusion through the semipermeable membrane into the dialysate. Dialysate has the same concentration as blood plasma, without the metabolic wastes. Dialysate fluid (waste) is drained, not re-used, it needs to be continually replaced.
Must be done for 3-4 hours, 2-3 times per week making it very time consuming. Can be done at home or hospital.
Only limited amount of fluid or waste can be removed from the blood; other substances like sodium phosphate and potassium ions do not diffuse quickly & may accumulate in the blood. For this reason, patients must follow a specific diet to prevent this from happening.
Diagram on slides 98-100
94
Explain how dialysis is used to assist with the effects of kidney disorders.
Dialysis is an artificial method of removing waste substances from the blood and regulating levels of circulating chemicals (functions usually performed by the kidney).
The main function of a dialysis machine is to remove metabolic wastes that have built up in a person's blood.
There are 2 common types of dialysis -
1. Haemodialysis -
2. Peritoneal dialysis.
95
How does Peritoneal dialysis assist with the effects of kidney disorders. (Draw diagram to support)
This type of treatment can be done at home.
There are 2 types - daytime bags (continuous ambulatory peritoneal dialysis) or automated peritoneal dialysis which is done overnight.
A tube (catheter) carrying dialysate is inserted into the abdomen - peritoneal cavity
The peritoneal cavity has a lining called a peritoneum. The dialysate solution empties into the peritoneal cavity.
The dialysate is made to attract water, via osmosis and waste eg: urea, potassium and phosphate, via diffusion from your blood through the peritoneum.
The bag needs to be changed 4 times per day.
Diagram in video and on slide 102
96
Homeostasis
The maintenance by an organism of a relatively constant internal state, regardless of external changes in the environment. It is important to maintain this constant internal state to ensure optimal metabolic efficiency. Metabolism is controlled by enzymes, and enzymes function most efficiently within specific ranges of temperature, pH etc. Homeostasis typically involves negative feedback loops that counteract changes of various properties from their target values, known as set points. They do this in 2 stages; Detecting the change, Counteracting the change.
97
Hypothalamus
A region in the brain called the hypothalamus, is an important control centre of maintaining homeostasis. It contains receptors for certain factors such as body temperature and blood glucose levels.
The hypothalamus acts as a link between the nervous and endocrine systems and sends messages to the effectors to carry out a response.
98
Effectors
Effectors in the body respond to the change to bring the cells back to homeostasis (balance).
Effectors may be
Muscles – contract and relax to bring about movement.
Glands – Secrete chemical substances eg. Hormones, insulin, aldosterone
These effectors bring about a response that will reverse or counteract the change.
The link between detecting and counteracting the change is the control centre.
99
Explain why we need to have functioning kidneys. What happens if your kidneys stop working?
To remove nitrogenous wastes from the bloodstream. To regulate salt and water concentrations in blood. Non-functioning kidneys cause a buildup of wastes affecting the pH of blood, and thus, enzyme activity.
100
Draw a negative feedback loop showing internal body temperature regulation
Pg 473 of BIF
101
Draw a negative feedback loop showing blood glucose level regulation
Investigation 14.1 doc (or just look up)
102
Enzyme
Biological catalysts essential for maintaining metabolic efficiency.
103
Explain why Homeostasis is important for metabolic efficiency.
Enzymes are required to catalyse the metabolic reactions that keep us alive, e.g. respiration provides energy and digestion provides nutrition. Homeostasis maintains water and salt concentration, and the removal of wastes such as carbon dioxide and other metabolic wastes, to maintain internal conditions that allow maximum enzyme activity. Homeostasis allows internal conditions to be maintained in order to allow for the optimal functioning of enzymes to ensure that optimal metabolic efficiency is maintained.
104
Describe how the nervous system works.
Messages are transported around the nervous system via neural pathways. These messages travel very quickly along nerves to specific locations in the body. The information carried by nerves consists of messages transmitted in the form of electrochemical impulses. The actions involving the nervous system in homeostasis are involuntary and take place without conscious thought.
105
Describe the structure and function of the central nervous system.
Brain and spinal cord
- Receives information from the receptors, interprets it and initiates a response by the effectors.
- Sensory, inter and motor neurons are the cells involved
Both the brain and spinal cord are made of two types of nervous tissue;
106
Describe the structure of the peripheral nervous system.
Consists of:
sensory neurons: relay nerve impulses from the receptors toward the CNS.
interneurons: the link between sensory and motor neurons (CNS)
motor neurons: relay nerve impulses away from the CNS to the effectors.
(Draw each type and check with figure 14.11)
107
Neuron
A neuron is a nerve cell and consists of a cell body, dendrites and an axon covered by an insulating myelin sheath.
108
Nerve
A nerve is a bundle of specialised neuronal fibres or axons bound together like wires in a cable.
109
Describe the structure of a neuron
Cell Body – forms the grey matter of the CNS, and is the ‘control centre’ of the neuron containing the nucleus.
Dendrites – fine, branching extensions which conduct nerve impulses towards the cell body. (a single elongated dendrite is called a dendron – found in sensory neurons).
Axon – very long extension that forms the white matter of the CNS that conducts impulses away from the cell body.
Dendrites and axons are collectively referred to as neuronal fibres. They are often surrounded by a fatty, insulating cover, the myelin sheath.
The myelin sheath is produced and supported by Schwann cells on the outside - function is to protect and insulate these axons and enhance their transmission of electrical impulses.
If myelin is damaged, the transmission of these impulses is slowed down, which is seen in severe neurological conditions such as multiple sclerosis.
Nerve fibres are able to transmit messages rapidly along their entire length and pass them on to a successive neuron, over small gaps called synapses.
110
Neurotransmitters
Neurotransmitters are chemicals stored in vesicles at the end of the axon which transmit messages across the synapse. Dopamine and serotonin are examples of these neurotransmitters.
111
How are signals transmitted in the nervous system?
Signals are transmitted by nerves as electricity along the neuronal membrane and as chemical from one neuron to the next - Hence electrochemical signal. The signal changes from electrical to chemical to cross the synapse. When Na+ ions reach the axon terminal they cause the release of neurotransmitter molecules. When the neurotransmitter is released it travels to the dendrites of the next neuron. The dendrites membrane is stimulated to become permeable to Na+. This therefore initiates a nerve impulse (action potential) in the next neuron (message is passed on). The neurotransmitter is broken down by an enzyme so it can be removed from the receptor once the AP has passed, ready for the next one.
112
Name three types of receptors and describe the function of each.
Thermoreceptors detect changes in temperature. They are nerve endings sensitive to heat or cold and send info to the brain about external temperature.
Chemoreceptors detect the concentration of certain chemicals inside the body such as CO2 and O2. They also detect pH.
Osmoreceptors detect changes in osmotic pressure and are located in the hypothalamus. Osmotic pressure in the blood is determined by the concentration of substances dissolved in the blood plasma.
113
Label the following on a diagram of the brain;
| Cerebrum, Cerebellum, Pituitary gland, hypothalamus, medulla oblongata.
Page 487 BIF
114
Describe how the endocrine system works.
Works with the nervous system to maintain homeostasis through the release of hormones. Hormones travel in the bloodstream to cells possessing the receptors for the particular hormone. These are known as target cells. The hormones cause these cells to respond in a way that will maintain homeostasis
Hormones achieve this by influencing the activity or concentration of particular enzymes in these cells.
Glands can be stimulated to secrete hormones by:
messages from the nervous system, other hormones, or receptors located in the particular gland.
115
Hormones
Hormones are chemical messages that are produced by the endocrine glands.
116
Vasodilation
The process by which blood vessels dilate (expand), bringing blood closer to the skin and allowing heat to escape.
