Module 8 Flashcards
What is homeostasis
maintenance of an internal environment despite changes in the external environment.
Explain what a negative feedback loop is with steps
A system where change is detected and counteracted to return body to its optimal state.
- A change occurs
- The change is detected by an appropriate receptor
- Receptor sends a signal to the control centre
- Control centre sends a signal to an appropriate effector
- Effector responds to the signal.
Explain the negative feedback loop for temperature regulation
Heat
1. Stimulus: body temeprature rises over 37 degress
2. Receptor: thermoreceptor detects change, sent to hypothalamus
3. Effector
* Vasodilation: Capillaries fill with warm blood so more heat can radiate from the skin’s surface
* Sweating: sweat glands activate and secrete perspiration which is vaporised by heat
Cold
1. Stimulus: body temeprature drops below 37 degress
2. Receptor: thermoreceptor detects change, sent to hypothalamus
3. Effector
* Vasoconstriction: blood is diverted from capillaries to minimise heat loss from skin
* Shivering: muscle contractions producing heat
Explain the negative feedback loop for blood glucose level regulation
Hyperglycaemia
1. Stimulus: BGL rises above 4-6mmol/L
2. Receptor: Beta cells in pancreas detects change
3. Effector: Hormone inslulin is released, increasing rate of glucose taken up by body cells and causes liver to store sugar as glycogen
Hypoglycaemia
1. Stimulus: BGL falls above 4-6mmol/L
2. Receptor: Alpha cells detect change
3. Effector: Hormone glucagon is released causing the liver to break down glycogen and release glucose in blood
Explain the behavioural adaptations in endotherms that assist in maintaining homeostasis
- Licking (cats) heat evaporates through saliva
- Panting (dogs) expells hot air
- Seaking shade / sun (cats) heat or cold radiation
Explain the structural adaptations in endotherms that assist in maintaining homeostasis
- Blubber (whale) insulates from cold water
- fur (polar bear) Insulates skin from cold air
- SA:V ratio - higher for hot and lower for cold () heat easily loss or kept
Explain the physiological adaptations in endotherms that assist in maintaining homeostasis
- Hibernation (bears) inhabit inhospitable environments
- Sweating (horses) expelling heat through vapour
- Vasodilation (humans) more heat can radiate from skin
Explain the internal coordination system of neural pathways that allow homeostasis to be maintained
Thr nervous system uses electrochemical impulses in nerves to relay information such as stimulus reception, interpretation and generation of an appropriate response
* Sensory neurons receive information and send to CNS
* Motor neurons from CNS sends a response to effector organs
E.g. thermoreceptors detect hot surface -> sensory neurons send message to CNS -> motor neurons make muscle move
Explain the internal coordination system of hormones that allow homeostasis to be maintained
The endocrine system consists of glands which secrete hormones into the bloodstream and travel to targeted cells, triggering a specific response.
E.g. Beta cells detect high BGL -> pancreas secreates insulin -> liver absorbs abd stores glucose
Explain the homeostasis mechanisms in plants
- Stomata: opens early morning and evening in cool temperature for photosynthesis but closes during intense heat and sunlight, preventing dehydration
- Thick and waxy cuticle: insulates water from excess sunlight, decreasing evaporation rate
- Shiny leaves: reflects sunlight, reducing internal temperature and rate of transpiration
Explain the causes and effects of genetic non-infectious diseases in humans
Cystic Fibrosis
Cause: Mutation involving deletion of three base (CCT) in CF gene.
Effect: Effects cells responsible for secretion of mucus, sweat and digestive fluids. Individuals may have problems with breathing or performing exercise.
Explain the causes and effects of non-infectious diseases caused by environmental exposure in humans
Skin cancer
Cause: Thymine dimer – bonding of thymine bases on same DNA strand.
Effect: Discoloured area of skin, yellow discolouration. Dilation of blood vessels. Destruction of elastic tissue.
Explain the causes and effects of non-infectious nutritional diseases in humans
Iron deficiency
Cause: Insufficient intake of iron
Effect: Tiredness and muscle weakness, pale skin, headache, dizziness, light- headedness
Define incidence, prevalence and mortality rate
Incidence: number of new cases per 100,000 in a population
prevalence: total number of cases per 100,000 in a population
Mortality rate: number of deaths
Analyse the treatment/management for further reasech of a disease caused by environmental exposure
Cancer
* Chemotherapy: drugs eliminating cancer cells during mitosis
* Surgery: localised melanoma cells cut out
* Monoclonal antibodies: injection of antibodies specific to particular antigen on cancer cells
Analyse the treatment/management and possible future directions for further reasech of a disease caused by environmental exposure
Immunotherapy: stimulates body’s immune system. Cytotoxic T cells are removed and modified to have t-cell receptors speicifc to a protein expressed on cancer cells, binding to it and causing apoptosis.
What is the purpose of epidemiological studies?
Epidemeology study of how diseases occur in a population and why, utilising large amounts of data to demonstrate correlation between incidence or prevalence with a social, geographical or lifestyle factor in order to infer causation.
Evaluate methods used in an epidemiological study
- Sample range (age, lifestyle, ethnicity): must include to eliminate bias
- Sample size (local, state, national): the larger, the more valid
- Control variable: reliability
- Data collection method: accuracy
Evaluate the benefits of epidemiological studies
Important role in public health:
* Creating public policy and laws
* Deciding allocation of funding and research
* Determine where more education is needed
Downsides: timely, costly, hard to establish true cause
Evaluate the effectiveness of educational programs and campaigns as a non-infectious disease prevention strategy
Addresses how disease is cause and how it can be prevented
e.g. Slip, slop, slap addresses nation-wide problem of skin cancer and sun-protection methods to prevent it including sunscreen abd wearing hats
This is highly effective in promoting health in Australia and protective actions. This campaign exhibited an overwhlemily positive result, decreasing incidence from 25/100,000 to 14/100,000 in 14 years
Evaluate the effectiveness of gene therapy as a non-infectious disease prevention strategy
Used for recessive genetic diseases, a normal allele is introduced through a vector into a cell in place of a missing or defective allele, correcting the disease.
E.g. For PKU, normal allele for PAH gene is deposited into liver cells, allowing phenylalanine to be properly converted into tyrosine
Explain how the ears work
Sound waves funnel through the ear canal to the ear drum, causing it to vibrate at the same frequency. This makes the ossicles vibrate and amplify the vibrations which pass the cochlea where the cillia in the organ of Corti detect them. When the hair cells move according to frequency and amplitude, electrical nerve impulses are generated and travel through the auditory nerve to the cerebrum of the brain where sound is decoded and interpreted.
Explain the cause of hearing loss
Sensorineual hearing loss: damage to inner ear/nerves due to loud noise, age, illness or genetic disorders
Conductive hearing loss: Mechanical disruption to the middle ear due to infection, perforated eardrum, damage to bones
Evaluate the effectiveness of technology that is used to manage and assist with the effects of hearing loss
Cochlear implants: electronic device that gives hearing to those profoundly deaf due to damaged hair cells. A speech processor detects sound and converts it into digital code, transmitted to the implant where it is converted to electrical impulses. This travels along an electrode directly to the optic nerve in the cochlea which is recognised by the brain. -> should be implanted young, trained to understand, not full sound, expensive
Bone conduction implants: improves hearing for those with damanged middle ears. External sound processor detects and converts sound into vibrations whuch are directly transferred thorugh bone to the cochlea. The hair cells converts this into nerve impulses, sent to the brain. -> bypass mid n outer ear, requires surgery, infection
Hearing aids: Overcomes loss of sensitivity in the cochlea through microphone detecting sound and converting it to an electrical signal which is amplified and made clearer, then converted back to sound by receiver and transmitted into the ear through a speaker. -> different shapes and sizes, cheaper, all ear must function
Explain how the eyes work
Light enters the cornea thorugh the aqeous humour and gets refracted by the lens which change shape accordingly. to focus the light onto the retina. This is transmitted into nervous signals which travel down the optic nerve to the brain where it is interpreted.
Accomodation
* near objects, cillary muscles contract
* far objects, cillary muscles relax
Explain the cause of visual disorders
Myopia: abnormal lens or shape of eye causing focal point to lie before the retina
Hyperopia: abnormal lens or shape of eye causing focal point to lie after the retina
Astigmatism: Cornea is improperly shaped, causing light to enter the eye one different angles and have multiple focal points, resulting in blurriness
Cataracts: With age and exposure to UV, lens becomes cloudy
Evaluate the effectiveness of technology that is used to manage and assist with the effects of visual disorders
Spectacles and contact lenses:
hyperopia: convex lens brings focal point closer
myopia: concave lens bring focal point further
Laser eye surgery:
A small circular flap is created in the cornea using a laser. A laser is then used to vaporise material in the corneal stroma to reshape the cornea, correcting refactiver errors. The flap is replaced and the eye can heal.
-> high success rate, dry eyes, haemorrhage, pain
Explain how the kidney works
Blood comes into the nephrons through the artery where the high blood pressure squeezes out everything except for blood cells including glucose, salt and urea. This is collected in the bowman’s capsule, travelling through the loop of Henle and along the capillaries where it is reabsorbed while urea remains and is collected in the bladder for excretion.
Explain the cause of loss of kidney function
Chronic kidney disease
* Damaged blood vessels due to high blood pressure or diabetes
* Autoimmune disease: body attacks kidney
* Kidney stones: high sodium diets causing blockages
Evaluate the effectiveness of technology that is used to manage and assist with the effects of loss of kidney function
Dialysis:
Blood is pumped out of their arm and into a machine and through a dialyser where fresh dialysate runs along the blood and urea diffuses into the dialysate, filtering the blood.
-> Effective in cleaning blood, inconvenient, takes hours, multiple times a week
