bio notes

Homeostasis

The body's automatic process of keeping a stable and balanced internal state. Helps regulate blood pressure, body temp, glucose levels, ph level.

• Both the nervous system (uses nerve impulses) and the endocrine system (uses hormones secreted by glands) are involved in maintaining homeostasis. 

Negative feedback loop

Occurs when a variable throws the body out of balance causing the body to counteract in response to maintain homeostasis.

• Stimilus → Receptor → Control Center → Effector → Response

Temperature Homeostasis ( Negative Feedback Loop)

 Recognised by thermoreceptor (receptor), nerves transmit information to hypothalamus (control center), effectors trigger action to increase/decrease temperature → temperature respond by increasing/decreasing.

• Increased temp: sweat glands, vasodilation, evaporative cooling.

• Decreased temp: shivering, vasoconstriction, goosebumps.

Glucose homeostasis (Negative Feedback Loop)

Blood glucose sugar level increases/decreases based on foods being eaten and physical activity. More carbs= more insulin. Less carbs = more glucagon.

• Hyperglycaemia: BGL too high, detected in pancreas by beta cells, releases insulin, causing liver to convert glucose to glycogen= cells become more permeable=decreases.

• Hypoglycaemia: BGL too low, detected in pancreas by alpha cells, releases glucagon, causing liver to convert glycogen back to glucose= increasing BGL levels.

Endotherms

Organisms that use internal processes to regulate body temperature in a narrow range, regardless of the external temperature. E.g Mammals, Birds

Ectotherms

Organisms that cannot regulate their internal temperature and must adjust their behavior based on the external environment. E.g Reptiles, Fish

Kangaroo Adapations

• Structure: high density of feathers to trap heat, no muscles in feet only tendons, bone limits exposure of muscle to cold environment as the proteins would freeze.
  
  

• Behavioural: huddle together and rotatet to maintain internal temperature, they can also fluff their feathers up which can trap warmth, and keep cool..
  
  

• Physiological: counter current exchange as blood flow in the capillaries traveling up and down are placed side by side to exchange heat, which warms up cool blood, increases temperature of blood

Internal Coordination Systems

Nervous system: Consists of nerves that are extended all over the body and pass messages through electrical impulses.

• Neural Pathways: requires messages to be sent around the body, to and from the control centre. Consists of the brain and spinal cord and peripheral nerves.

Endocrine system: Hormones are signalling molecules that regulate the activity of specific target cells, interacting with specific receptors

• Hormones: Chemical messenger molecules, transported by the bloodstream.

Regulating Stomata Opening

Plants maintain internal water homeostasis through regulation of stomatal opening.

• Guard cells control the opening and closing of stomata, allowing CO₂ to enter for photosynthesis while controlling water loss through transpiration. During dry conditions, stomata can close to reduce water loss and prevent dehydration.

Thick waxy cuticle

Plants also maintain water balance through their thick waxy cuticle.

• The waxy cuticle forms a waterproof barrier, preventing excessive evaporation from the leaf surface and reducing water loss through transpiration in unfavourable conditions.

Types of non-infectious dieases

• Genetic disease: Down syndrome is the result of having additional 3-chromosome 21. This causes mild to moderate retardation and poor muscle tone; higher risk of disorders

• Nutritional diseases: Anemia is the result of iron deficiency. This causes tiredness and muscle weakness, pale skin, headache, dizziness, light headedness.

• Environmental Exposure: Melanoma is the result of UV radiation from the sun. Interferes with the correct functioning of the body. Discoloured area of skin, yellow discolouration. Dilation of blood vessels. Destruction of elastic tissue.

Cancer

A disease characterized by uncontrolled cell division, leading to the formation of benign or malignant tumors.

• Bowel cancer is the result of a growth (tumor) on the inner lining of the large intestine and/or rectum. Symptoms include diarrhoea, constipation, blood in the faeces, weight loss, a lump in the anus or rectum and abdominal pain

Incidence, Prevalence, Mortality

• Incidence:  the number of new cases diagnosed.

• Prevalence: the total number of cases in the population.

• Mortality: the number of deaths due to a condition.

Types of studies

Descriptive studies: Provides information about the frequency of the disease, which section of the population is affected (age, gender, SES ect), geographic location and timeframe. Allows early hypotheses on cause of disease.

Intervention studies: Testing the effectiveness of a treatment or public health campaign e.g. experiment study allowing testing of new drugs by giving one group the trial drug and the other placebo.

Analytical studies: Used to collect more data to statistically analyse hypotheses to find likely causes of disease. Uses mortality, morbidity, incidence and prevalence.

• Cohort studies: studying two or more similar groups of people who are free of the disease and exposing one to the possible cause. They are then followed for some time to compare incidence. 

• Case control: comparing people with the disease (case) to people without (control) and comparing differences to find the cause.
  
  

Evaluating Epidemlogical Studies

• Conducted over a long period of time

• Study a large sample size (thousands) 

• Collect relevant data from affected and unaffected people

• Participants need to represent the wider population (e.g. age, gender, diet) 

• Controls should have similar aspects to the case cohort (e.g. similar ages if that isn’t being tested)

• Collect data on incidence, prevalence, mortality and morbidity -> use this for statistical analysis

• Identify causes of disease and risk factors

Educational Programs / Campagins

Provides information and educates the population about effects of a disease and its risk factors (and therefore protective behaviours).

• Slip, slop, slap, seek, slide (for skin cancer e.g. melanoma): Involved television advertisement, sunscreen vans, catch phrase, jingle/song, free bottles on sunscreen and more gov. funded research → Led to a decline in melanoma

Genetic Engineering

 The use of transgenic species to prevent nutritional diseases ➔ vitamins deficiencies and poor diet are issue in developing countries; transgenic species can supplement certain nutrient (e.g. Golden rice).

Hemodialysis

A type of dialysis that uses a machine to filter blood outside the body.

Myopia (short-sightness)

Eye can focus on near objects, but the focal length when viewing distant objects is too short. Concave glasses help light rays to diverge slightly before entering the eye so that the image is then focused on the retina.

Hyeropia (long-sightness)

Eye can focus on distant objects, but the focal length when viewing near objects is too long. Caused by, convex glasses help light rays to converge slightly before entering the eye so that the image is then focused on the retina.

LASIK Surgery

It is used to correct myopia, hyperopia and astigmatism which are caused by refraction errors in the eye which can be caused by problems with the shape of the cornea. In LASIK surgery a thin flap is opened on the surface of the cornea, a laser then reshapes the cornea to provide the correct refraction and the flap is laid back into place.

Types of Hearing Loss

Conductive hearing loss: Caused by blockage or damage in the outer and/or middle ear.

• This includes blockages of the ear canal e.g. wax or foreign objects ,perforated eardrum e.g. trauma (pencil)
  
  

Sensorineural hearing loss: caused by damage to, or malformation of, the inner ear, including parts of the cochlea, hair cells or auditory nerve preveting vibrations being transformed into electrical impulses to be sent to the brain for interpretation. 

• The causes include excessive noise exposure, heredity, birth defects, infections, tumours, medication and ageing.

Types of Ear Technology

Hearing aids: electronic devices that can amplify sounds entering the external ear.Can help with conductive or mild sensorineural hearing loss e.g. in the elderly. Consist of microphone, amplifier, receiver, speaker.

Bone cochlear implants: External processors that send sound as vibrations through bone directly to the inner ear. Can help with more severe hearing loss, bypassing both the outer and middle ear.

Cochlear implants: 'bionic ear' sends sound as electrical impulses directly to the auditory nerve. Can help to treat severe to profoundly deaf people with missing/damaged hair cells.

Kidney Failure

Occurs when kidneys are no longer able to filter blood effectively. Usually involves damage to the nephrons. T

• This prevents the nephrons from carrying out its function properly: filtering, reabsorption and secretion of wastes not being removed efficiently and an inability to balance water and salt levels in blood.

Kidney Dialysis

Dialysis is a treatment that filters waste and excess fluid from your blood when your kidneys are failing through the diffusion of small solute molecules through a partially permeable  membrane in a dialysis machine.