Disruptions to homeostasis

Question 1

Hormonal Disruptions

Answer 1

• disruptions to thyroxine production
• disruptions to insulin production

Question 2

Hyperthyroidism

Answer 2

• caused by an overactive thyroid gland
• as a result, the body produced too much thyroxine
• it can be the result of an autoimmune response causing Grave’s Disease which resutls in an enlarged thyroid gland (thyroid gland working too hard)
• Symptoms: rapid heart rate, weight loss, increased appetite, fatigue, sweat, anxiety and with grave’s disease, protruding eyes
• Treatment:
  1. drugs that block the thyroid glands use of iodine (needed to form thyroxine)
  2. surgery to remove all or part of the thyroid gland
  3. consume radioactive iodine which kills cells of thyroid gland as they absorb the iodine. Other cells in the body dont absorb the iodine so remain unaffected.

Question 3

Hypothyroidism

Answer 3

Caused by:

• far more common
• problems with the thyroid gland/pituitary gland/hypothalamus
• could also be due to a lack of iodine in the diet preventing thyroid gland from making thyroxine
• Hashimoto’s disease: attack of immune system of thyroid gland
• cancer and surgical removal of thyroid gland
• Results in low thyroxide production
• symptoms: slow heart rate, unexplained weight gain, fatigue/lack of energy and intolerance to cold, goitre (an enlarged thyroid gland as attempts to increase thyroxine production, the released TSH from anterior pituitary gland not used, causes a build up)
• treatment: increase iodine in diet, take synthetic forms of thyroid hormones (this will need to be closely monitored to ensure dosage is correct, if too low it won’t relieve symptoms, too high can result in hyperthyroidism)

Question 4

Diabetes Mellitus (Type 1) - insulin dependent

Answer 4

• an autoimmune condition in which the beta cells have been attacked by the immue system, preventing the production of insulin
• blood glucose levels can’t be regulated after a meal
• sufferers may experience hyperglycaemia (blood glucose levels are too high) and hypoglycaemia (blood glucse too low)
• hypogycaemia can results in symptoms of dizziness, disorientation and a diabetic coma which can be fatal
• in untreated diabetics, the kidney nephrons remove glucose from the blood. This can results in an excess of water moving into the nephrons producing large volumes of urine with glucose in it. This can make the suffere feel thirsty.
• it is treated by regular injections of insulin (this insulin was formerly extracted from pacreas of pigs but is now produced by genetically modified bacteria)
• long term effects = kidney failure, heart attack, stroke, blindness or nerve damage
• no current cure but maybe in future stem cells could be used to replace faulty beta cells

Question 5

Diabetes Mellitus (type 2) - non-insulin dependent

Answer 5

• appears to be genetic link but the following lifestyle choices increase the risk of getting it:
• a sedentary lifestyle
• high blood pressure
• • obesity
• a poor diet high in fat, sugar, salt and low in fibre
• high blood cholesterol
• smoking
• insulin production can be disrupted but generally some insulin is still produced
• the body’s cells become resistant to insulin, so they lose the ability to respond to the insulin to take up glucose from the blood and lower blood glucose
• Symptoms: excessively thirsty, frequent urination, blurred vision, lethargic and dizzyness
• Treatment: Management program to keep blood glucse levels within the normal range e.g. changing lifestyle choices, in particular exercise, diet (reducing sugar intake), maintaing a healthy weight and sometimes medications (including insulin).

Question 6

Behavioural Disruptions

Answer 6

There are many things we can do to disrupt the stable internal environment of the body, including:

• drugs
• excessive exercise
• eating habits

Question 7

Drugs 1

Answer 7

• Caffeine: stimulant
• increases heart rate
• causes release of adrenaline which also increases heart rate
• acts as a diuretic which can result in dehydration
• Alcohol: depressant
• stimulates insulin production which results in low blood sugar
• inhibits production of ADH therefore results in less water reabsorbed, increased urine output and dehydration
• Amphetamines:
• causes release of noradrenaline, dopamine and serotonin neurotransmitters in the brain
• improve alertness and motivation but also affect appetite and weight control

Question 8

Drugs 2

Answer 8

• Ecstasy: synthetic amphetamine:
• causes a release of noradrenaline, dopamine and accumulation of serotonin
• initiates body’s fight or flight response so user feels more energetic
• increases HR, BP, BR, causes sweating and dehydration and decreases appetite. May cause heart palpitations and vomiting in high doses.
• Cocaine: stimulant
• blocks removal of dopamine, noradrenaline and serotonin from synapse
• increase HR, BP, body temperature and BR, dilation of pupils and loss of appetite
• Heroin:
• binds to receptors in the brain resulting in euphoria, decreased perception of pain and relief from anxiety
• it slows down BR, BP and body temperature
• can result in loss of consciousness and death

Question 9

Excessive Exercise

Answer 9

• if exercise exceeds energy consumption over a long period of time it can result in the body breaking down protein to provide energy (decreasing muscle mass)
• menstruation in females stops - amenorrhoea (increases risk of osteoporosis)
• calcium levels can be affected resulting in loss of calcium from the bones and increasing risk of osteoporosis
• places greater strain on the heart and can lead to cardivascular disease

Question 10

Eating habits - lack of a balanced diet

Answer 10

• lack of iodine = hypothyroidism
• lack of iron = anaemia
• lack of calcium and vitamin D = osteoporosis
• vitamin K deficiency = blood clotting mechanisms won’t work effectively
• excessive vitamin A = nausea, headache, hair loss, liver problems
• excessive salt = hypertension
• excess kilojoule = obesity
• kilojoule shortage = anorexia

Question 11

Disruptions caused by disease

Answer 11

• emphysema = breakdown of alveoli in lungs impacts homeostatis of oxygen and carbon dioxide concentrations in blood
• fever = malfunction of hypothalamus due to infection, disrupts homeostasis of temperature causing it to become too high
• hypertension = disruption of blood pressure resulting in it becoming too high