MINDARIE SENIOR COLLEGE
3A/3B Human Biological Science
Homeostatic Dysfunction
Hormonal causes of disruptions:
Diabetes mellitus
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Symptom:
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Role of insulin:
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Stimulate cells to take in glucose from blood.
Stimulate conversion of glucose into glycogen by liver and
muscle cells.
Dysfunction:
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Hyperglycaemia: abnormally high levels of blood glucose.
Insufficient insulin production or cells resistant to insulin
effects.
High levels of blood glucose.
Large quantities of glucose excreted in urine.
Types:
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Type 1 (insulin dependent diabetes).
Type 2 (non-insulin dependent or adult onset diabetes).
Type 1 (insulin dependent or juvenile diabetes ).
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Cause:
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Treatment:
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Fault in immune system causes destruction of beta cells in Islets of
Langerhans.
No insulin produced.
Tablets not suitable as insulin is digestible.
Regular injections of insulin
Programmable insulin pump
No cure
Long Term Effects:
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Kidney failure
Heart attack
Stroke
Amputations
Blindness
Nerve damage
Type 2 (non-insulin dependent or adult onset diabetes).
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Cause:
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Insulin is produced but cells do not respond to it.
Lifestyle disease.
Risk factors:
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Treatment:
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Inactivity
Obesity
Energy rich/low fibre diet
Hypertension
High blood cholesterol
Smoking
Often no symptoms – and not diagnosed.
Preventable by adopting a healthy lifestyle.
No cure
Early diagnosis can lead to successful management.
Long Term Effects:
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Heart disease
stroke
Kidney disease
Eye problems
Nerve damage
Skin and foot problems.
Hormonal causes of disruptions:
Excess or deficiency of thyroid
hormones.
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Symptom:
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Role of thyroxine and tri-iodothyronine:
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Stimulate carbohydrate, protein and fat metabolism.
Regulate basal metabolic rate.
Influence long term homeostasis of body temperature
Dysfunction:
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Too little or too much thyroid hormones (thyroxine and triiodothyronine)
Imbalance in Thyroid Stimulating Hormone from anterior
Pituitary leads to imbalance in thyroxine.
Large quantities of glucose excreted in urine.
Types of dysfunction:
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Hyperthyroidism
Hypothyroidism
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Cause:
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Graves’ disease (most common form)
Enlarged thyroid caused by immune system reaction.
Genetic predisposition.
Effects:
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Too much thyroid hormone secreted.
Types:
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Hyperthyroidism
Overstimulation of cells
restlessness
Rapid heart rate
Weight loss
Increased appetite
Anxiety/excitable
Fatigue
Sweating
Swings in mood and emotional state.
Protruding eye balls – exophthalmia - (Graves’ disease)
(Pres G W H Bush suffered this condition.)
Treatment:
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Drugs to block thyroid gland’s use of iodine.
Surgery to remove all or part of thyroid gland
Radioactive iodine used to over active thyroid cells.
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Cause:
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Too little thyroid hormone secreted.
Problems with hypothalamus, pituitary gland or thyroid gland.
More common of the two conditions (6%-10% Australian females suffer)
Lack of iodine in diet prevents thyroid secreting sufficient hormones.
Surgical removal (cancer treatment) of gland or parts of gland.
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Goitre
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Effects:
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Thyroid gland becomes enlarged in attempt to produce more hormone.
Cretinism
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Deficiency of iodine in maternal diet
Baby severely mentally and physically retarded, impaired movement and hearing.
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Immune system attacks thyroid gland
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Hypothyroidism
Hashimoto’s disease
Treatment:
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Inclusion of extra iodine in diet (if this is the cause)
No cure.
Carefully monitored doses of thyroid hormone (tablets)
Behavioural causes of
homeostatic disruption
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Drugs
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Non-medicinal drugs may interfere with nerve impulse
transmission by binding to receptor sites.
Caffeine
Effects
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Stimulates metabolism and CNS
Increases heart rate
Increases kidney blood flow, increasing urine production.
Increases pulmonary blood flow and relaxes bronchioles,
increasing pulmonary ventilation.
Alcohol
Effects
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CNS depressant
Stimulates insulin secretion, lowering blood sugar levels.
Inhibits secretion of ADH, increasing urine output and
dehydration
More behavioural causes of
homeostatic disruption
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Drugs (continued)
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Amphetamine and methamphetamine
Effects
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Cause release of noradrenaline, dopamine (hormones and
neurotransmitters) and serotonin (neurotransmitter)
May enhance alertness, motivation and clear thinking
Disrupts homeostasis by affecting appetite and weight control
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Synthetic amphetamine
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MDMA (ecstacy)
Effects
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Cause release of noradrenaline, dopamine and accumulation of serotonin.
Initiates fight or flight syndrome, user feels more energetic
Increase heart rate and blood pressure
Increases breathing rate
Causes sweating and dehydration
Decreases appetite
In high doses – rapid rise in body temp and BP, heart palpitations,
vomiting.
More behavioural causes of
homeostatic disruption
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Drugs (continued)
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Cocaine
Effects
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Blocks removal of noradrenaline, dopamine and serotonin from synapse between
nerve cells
Stimulates CNS
Disrupts homeostasis by increasing heart rate, blood pressure, body temperature,
breathing rate, dilating pupils, loss of appetite.
Heroin
Effects
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Used medicinally as strong analgesic.
When injected recreationally, binds to brain receptors resulting in
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Intense euphoria
Decrease in pain perception
Relief from anxiety.
Profound effects on homeostasis
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Depresses control of breathing
Depressed control of blood pressure and body temperature
Irregular heart rate
Unconsciousness, coma or death (large dose)
More behavioural causes of
homeostatic disruption
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Excessive activity
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Well planned, monitored and not obsessively over
taxing exercise levels are beneficial
Excessive activity may cause physical damage to
tendons, muscles, ligaments, cartilages, bones and
joints.
Homeostatic dysfunction may result
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If nutrition is inadequate muscle may breakdown to
source energy
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Eating disorders are strongly linked to excessive exercise.
Great stress on heart may lead to cardiovascular
problems
Loss of Calcium deposition may lead to osteoporosis.
Amenorrhoea may occur if energy uptake is inadequate.
More behavioural causes of homeostatic
disruption
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Eating habits
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Deficiency diseases may result from inadequate intake of vitamins and minerals
Examples of deficiency:
 Iodine
 Iron
 Causes anaemia:
 insufficient haemoglobin
 Reduced oxygen carrying capacity of RBC’s
 Reduced rate of Cellular Respiration and energy release.
 causing weakness, fatigue, breathlessness, elevated heart rate.
 Vitamin B
 causes Pernicious anaemia (stem cell divisions don’t occur)
 Vitamin K
 Produced by bacteria in large intestine.
 Lack causes reduced blood clotting ability.
 Homeostasis compromised if excessive blood is lost.
Energy balance (intake and use) is a complex but essential element of homeostasis.
Alimentary canal, hormones, CNS (hypothalamus), Autonomic NS are linked.
Imbalances may be caused physically or psychologically.
Lifestyle, eating habits and natural selection play a role in contributing to obesity
epidemic
Homeostatic disruption caused by disease.
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A disease is any condition in which normal functioning is impaired.
Some diseases have direct effects on homeostasis
Emphysema:
Alveolar walls breakdown, reducing surface area for gas exchange
 results in difficulty in taking in oxygen
Cause:
 Smoking
Symptoms
 Breathlessness, initially during activity, and eventually, constantly
Treatment:
 damage is irreversible
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Fever:
 An elevation of body temperature
A symptom of a disease
Cause:
 Many infections.
Symptoms
 1 or 2 degrees C increase in core temperature.
Effect:
 Helps immune system overcome infection
 Disrupts homeostasis by affecting many body reactions - increasing temp beyond
optimal range.
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More homeostatic disruption caused
by disease.
Hypertension:
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Cause:
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Homeostatic mechanisms unable to keep blood pressure within normal range
 Genetic factors,
 excessive salt intake
 obesity
 Inactivity
 High alcohol intake
 Kidney disease
Poor lifestyle choices
Effects
 Significant risk factor for cardiovascular disease and kidney failure
Treatment:
 Adopt a healthy lifestyle
Injuries:
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Examples:
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Excessive blood loss limits supply of oxygen and glucose, and removal of carbon
dioxide and wastes.
Punctured/collapsed lung impairs gas exchange
Immobility limits venous return
Spinal cord injuries reduce innervation of respiratory muscles.
Hormonal treatments to
homeostatic disruptions
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Hormone replacement therapy
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To treat symptoms of menopausal women
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hot flushes and night sweats
Uncomfortable skin sensations
Headaches
Thinning and dryness of walls of vagina
Aches and pains
Frequent urination
Reduced libido
Tiredness and irritability
Mood disturbances, loss of self esteem, depression
Sleeping difficulties
Treatment
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May not require medical intervention
Severe symptoms may need HRT
Oestrogen and progesterone prescribed to counteract loss or irregularities
in natural secretions
Carefully managed doses given as tablets, patches, gels, implants or nasal
spray.
Risks and benefits must be carefully assessed
May lead to side effects – bleeding, bloating, breast tenderness, slight
increase in risk of breast cancer, CV disease, thrombosis.
More hormonal treatments for
homeostatic disruptions
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Corticosteroids and treatment of
rheumatoid arthritis
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Rheumatoid arthritis
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A crippling disease
Immune system attacks synovial membrane of joints,
causing painful swelling and deformity
Treatment
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Corticosteroids, closely related to cortisol (the ‘ stress
hormone’ secreted by the adrenal gland)
Act on immune system to block production of substances
which stimulate allergic and inflammatory responses
Side effect – reduce resistance to infection due to
interference to WBC’s.
Usage of lowest possible doses must be managed very
carefully
Behavioural treatments for homeostatic
disruptions
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Control of reproduction
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Intervention in Menstrual Cycle and Ovarian Cycle
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Female infertility
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Hormonal contraception
 Combined Pill (synthetic progesterone and oestrogen)
 Prevent ovulation
 Reduce ability of sperm to enter uterus
 Reduce likelihood of implantation
 Mini Pill (progesterone substitute)
 Thickens mucus plug in cervix preventing entry of sperm
 Reliable, effective and allows personal choice.
 Some risks involved with intervention to normal body functioning
 Combined pill - Headaches, nausea, increased appetite, breast
tenderness, increased incidence of heart attacks, strokes, blood clots
 Mini Pill – fewer complications, but less reliable if not used with
discipline.
Drugs, synthetic forms of pituitary hormones, can be used to induce ovulation
High risk of multiple pregnancy
Use of in-vitro fertilization
Side effects to hormones, multiple pregnancies, premature birth must be
considered.
Male infertility
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Problem with up to 50% of infertile couples due to male sperm problems
Treatment with gonadotrophins over several months may help.