1. homeostasis: how is an organism’s internal environment maintained in response to a changing external environment?

1.1

NEGATIVE FEEDBACK

• homeostasis: the proccess by which organisms maintain a relatively stable internal environment, especially for optimum enzyme function

• tolerance limits: variables in internal environment (temperature, glucose) are maintained within a narrow range eg. 30-45 degrees for body temperature and has an ideal value known as the set point 37 degrees

1.2

ADAPTATIONS

• adaptation: any inherited characteristic, process, or behaviour that aids an organism’s survival in a particular habitat. arise due to natural selection

• ectothermic: body temperature changes with ambient temperature/metabolism generate little heat eg. reptiles, amphibians (water holding frog)

• endothermic: body temperature remains relatively constant. Maintenance requires complex metabolic processes and therefore more food eg. mammals and birds

• behavioural: the activities and behaviours of the organism eg. red kangaroo position so tail is in sun, bilby come out at night to avoid heat/predators.

• structural: the physical characteristics of the organism eg. blubber in the Australian fur seal, SA:V of Äfrican elephant ears

• physiological: the processes carried out by the structure/functions within the body eg. evaporative cooling, torpor by wombat (body temperature drops, metabolism, heart rate and respiratory rate decrease, reduced response to external stimuli

COORDINATION

• Coordinating systems of the body work to maintain body temperature. The nervous & endocrine systems coordinate and provide pathways of communication for negative feedback process

  Nervous System = neural pathways

• very fast, up to 100m/s

• CNS: brain & spinal cord. transmits messages to and from the brain and controls spinal reflexes

• PNS: branching network of nerves, all enter/leave CNS eg. sensory nerves (arise from internal/external sensory receptors carry to CNS, interneurons carry impulses from sensory to motor neurons, motor nerves carry from CNS to effectors = muscles (somatic or autonomic)

  Nervous Control:

• Stimulus: a change occurs in the environment (internal/external) → Receptor: sensory receptors detect the stimulus and convert into electrochemical impulses that are directed to the CNS → Control centre: the brain determines the response. different parts of brain = different functions eg. hypothalamus maintain temperature → Effectors: motor neurons carry impulses from the spinal cord to effectors eg. muscles, glands, organs → Response: muscle/gland responds accordingly

• Reflex: bypass brain
  Nerve Structure: cell body (similar to other cell body), dendrites(receive signals from other neurons and carry to cell body), axon (carries messages away from cell body)

• myelinated fibres: white matter in CNS, unmylenated fibres &cell body: grey matter

• Synapse: space between axon of one neuron and dendrite/cell body of next

• electrical synapse: action potential moves directly from one neuron to the next

• chemical synapse: impulse reaches end of axon, release chemicals (neurotransmitters) that travel to next neuron

1. stimulus causes Na+ channels to open, potassium pumps to close. Na rush in, increase voltage, may reach threshold

2. repolarisation: Na+ channels close, K+ open, inside of cell more negative

3. hyperpolarisation: K+ channels close relatively slowly, inside of cell temporarily negative

4. resting state: Na/K pumps open and restore resting potential

• action potential: change in electrical potential of the cell membrane of axon, caused by electrochemical impulse

• Resting Membrane Potential: -70mV as there are more Na+ outside the cell

Endocrine System

• glands & hormones

• long-lasting but relatively slow

• hormones: chemical messengers that are transported by the bloodstream/extracellular fluids that change cell behaviour to maintain homeostasis. reach cell → bind to receptors → trigger response

• pituitary gland: releases hormones (often on direction of hypothalamus) to regulate other glands

• thyroid & parathyroid: release thyroxine, regulate body temp and blood calcium

• adrenal: on top of kidneys, secrete cortisol (stress & conversion of carbohydrates)

• pancreas: insulin & glucagon

• hypothalamus: links nervous & endocrine system. sorts sensory information and produces numerous hormones.

Plants

• only use hormones

• auxins (growth, bending towards light), cytokinins (cell division, seeds etc), gibberellins, abscisc acid (inhibit germination), ethylene (ripening and aging)

  Water Balance in Plants

• opening & closing of stomata. Turgid = open. Thick, waxy cuticles, sunken stomata, succulent leaves (storage), deep roots below water table, shallow roots to absorb surface moisture

2. cause and effects: do non-infectious diseases cause more deaths than infectious diseases?

2.1

Non-infectious diseases: not caused by pathogens and aren’t transmittable from one individual to another

Categories

Genetic Disease: mutations that occur in germ-line cells that affect whole zygote eg. Down’s Syndrome. point mutation/chromosomal mutation (incorrect number of chromosomes)

Diseases Caused by Environmental Exposure: Factors in the environment have potential to cause disease eg. poor water quality, availability, and sanitation, vector-borne diseases, poor ambient and indoor air quality, toxic substances and environmental change.

• Lifestyle: eg tobacco, drugs, alcohol can cause cancer, liver damage and mental health issues

• Physical: eg. UV exposure and loud noises cause skin cancer and deafness

• Chemical: Asbestos (lung disease), heavy metals. Disease depends on type/length of chemical exposure

Cancer: Normal cell growth/regulatory genes disturbed leading to uncontrolled cell replication and a tumour. Can be caused by environmental exposure. Benign cancer cells don’t spread (sarcoma/connective tissue, lymphoma/lymphatic tissue), malignant do (invade surrounding tissue, metastasis occurs, new blood vessels must develop).

Nutritional Disease: caused by lack of balance and correct nutrients.

• undernutrition: insufficient intake of quality/quantity of food eg. wasting, stunating and underweight

• micronutrient-related malnutrition: micro-nutrient deficiencies/excess eg scurvy(vitamin C), rickets (vitamin D), night blindness (vitamin A), anaemia (iron)

2.2

incidence: new cases in a specific time

mortality: deaths over a given time period

prevalence: number of people diagnosed with a disease that are still alive at the end of a given time period

3. epidemiology: why are epidemiological studies used?

Epidemiology: study patterns of disease in population

Helps determine cause, affected populations, guides development of treatment/prevention for hospitals, census, WHO, health practitioners etc results can be applied to large scale population (sanitation) or at risk (breast screening)

• Descriptive studies: distribution in relation to age, ethnicity, sex etc

• Intervention: evaluate treatment and prevention methods (eg. clinical trials)

• analytical studies: determine cause, risk factors & protective factors (observational/case-controlled compare diseased and healthy individuals, are retrospective & experimental compare individuals who are exposed to different risk factors, prospective)

Factors to improve validity: large sample size, variety of backgrounds, control group, conducted over long period of time

4. prevention: how can non-infectious diseases be prevented?

Educational Programs & Campaigns

Carried out by all levels of government, private organisations & health professionals. Aim to educate about risk factors.

Legislation: minimise risk factors, particularly those that are addictive. eg. Tobacco Plain Packaging Act 2011 all tobacco must display educational warnings and graphic imagery. bans on underage drinking etc

Screening Programs: Not educational campaigns but used in conjunction with campaigns!!! eg. A Gift For Life bowel screening kits + media

Paid Advertising: TV/radio/internet-based advertising eg. Slip! Slop! Slap! TV ads. key role in changing sun protection attitudes cases of melanoma in young people fell 5 per cent each year from the mid-1990s to 2010. launched 1981

School Based Education: programs delivered in schools, universities, worksites eg. NSW PDHPE curriculum education around alcohol, tobacco & other drugs

Genetic Engineering

Direct manipulation of an organism’s genome

Pre-Implantation Genetic Testing: IVF → 8 cell stage → singles cell removed and tested for certain genetic diseases (cystic fibrosis, Huntington’s disease, thalassaemia and muscular dystrophy). affected embryos discarded therefore highly affected

Mitochondrial Replacement Therapy: singular circular piece of genetic information, 37 genes, vital for apoptosis & energy within the cell. one mode of MRT involves placing mother genetic information in donor oocyte then fertilising. prevent diseases such as MELAS

Biofortification: increases nutritional value eg. golden rice rice contain genes from maize & soil bacterium, allows beta-carotene production, precursor to vitamin A. 1/4 to 1/2 million children suffer vitamin A related blindness.

Vaccines to prevent cancer: Human Papilloma virus linked to majority of cervical cancer & some other cancer cases. When administered pre-pubescently almost 100% effective in preventing infection

5. technologies and disorders: how can technologies be used to assist people who experience disorders?

EAR

Hearing Loss

Conductive Hearing Loss: issues with mechanical conduction of vibrations throughout outer and middle ear eg. perforated ear drum, infection, hardening of stapes bone, exposure to sudden loud noises, malformation. generally affects volume of noise. assisted by hearing aid & bone conduction implants

Sensorineural Hearing Loss: damage to inner ear including cochlea, hair cells or auditory nerve. usually permanent, affecting volume & clarity. caused by noise exposure, heredity, birth defects, infections, tumours, medication and aging. assisted by cochkear impants.

EYE

accommodation: lens must adjust curvature to refract light correctly for distant/close objects. for distant objects ciliary muscles relax, draw sclera back, flatten lens = less refraction of light. vice versa for close

myopia (short sighted): distant objects are focussed too far forward = blurred. due to elongated eyebal, inadequate refractory power of cornea, lens not flatten enough when cilliary muscles contract. can occur as a result of being in confined space

hyperopia (long sighted): light is focussed too far back, sometimes overcome by accommodation. due to rounded/short eyeball, lens too flat (eg. loss of elasticity old age), refractive power too great for shape of eye

Assistive Technologies:

Laser Surgery: reshape surface of eyes for better refraction eg. myopia, hyperopia, astigmatism (cornea curved more in one direction than other)

Cataract Surgery: natural clouding/yellowing of lens generally due to old age. ultrasound break up lens, fragments removed via suction. clear artificial lens in place

Bionic Eye: camera in glasses gathers data, sends directly to processing centres in brain, bypass rods & cones

KIDNEY

PROCCESS

1. Filtration: under high pressure blood forced through glomerulus (inside bowman’s capsule).All substances small enough will pass through walls of glomerulus eg. nitrogenous waste, water, ions etc. This becomes glomerular filtrate, rest remains blood

2. Reabsorption: returns essential components (sodium, potassium, chloride, calcium, hydrogen bicarbonate) reabsorbed by active transport and facilitated diffusion. solutes reabsorbed into medulla = water follows because osmosis = reabsorption of water

3. Secretion: contributes to urine formation. toxic substances removed. metabolic wastes eg. urea and ammonia (diffusion), drugs, hydrogen (active transport)

4. Removal: urine collects in pelvis of kidney before moving through ureters to bladder, then excreted

Hormonal Regulation

ADH/vassopressin: released if there is water loss eg sweating and blood is more concentrated. increases permeability of collecting duct, more water reabsorbed, urine more concentrated

aldosterone: if salt needs to be conserved eg. bleeding or diarrhoea, released by adrenal gland. increases permeability of distal convoluted tubules = increased reabsorption of sodium = increased absorption of water, decreased potassium= concentrated urine

Loss of Kidney Function

Many can survive with only one kidney. however severe loss of functioning can result in chronic kidney disease

Chronic kidney disease: results in build up of excess waste in bloodstream. Due to exposure to toxic chemicals, birth defects, kidney stones, infection, reduced blood flow, medication, artery problem (eg. high blood pressure). results in loss of function over time

Acute kidney failure: causes rapid loss of kidney function. decreased blood flow (eg. serious injury, burn, dehydration, surgery, septic shock) rapid decline in kidney function. autoimmune disease, urinary tract blockages, pregnancy and clots can also be factores

Dialysis

Treatment that substitutes for function of normal kidneys, instituted when 85-90% of functioning is lost. removes metabolic eastes, excess water and sodium. extends life expectancy 5-10 years

Haemodialysis: blood removed via vein → pumped through thousands of tiny hollow synthetic fibers (semipermeable membrane) → blood flows between fibers, dialysis solution around outside of fibres, water & wastes move between → cleansed blood returned to body

Peritoneal Dialysis: catheter placed into abdominal cavity → dialysate washes around intestines → peritoneal membrane acts as a filter between fluid and bloodstream → different types of solutions allow removal of different types of wastes