Endocrine Disorders

Question 1

What can go wrong with hormone signalling?

Answer 1

Secretion levels:
- Hyposecretion: too little hormone is secreted into the plasma
- Hypersecretion: too much hormone is secreted into the plasma

Sensitivity or hormone receptors:
- Hyposensitive: receptors are less sensitive; receptors get desensitised, causing them to respond less or not at all

Question 2

List the cortisol disorders

Answer 2

Addison’s Disease and Cushing’s Disease

Question 3

Describe Addison’s Disease: the causes, what it is and the symptoms

Answer 3

Common cause: autoimmune disease that attacks the adrenal cortex

Hyposecretion disorder: reduced cortisol and aldosterone secretion causes reduction in normal effects

Symptoms:
- Low blood pressure
- Craving salty foods; increased thirst

Question 4

Describe Cushing’s Disease: the causes, what it is and the symptoms

Answer 4

Common cause: adrenal cortex tumour or taking glucocorticoid medication for long periods

Hypersecretion disorder: excess cortisol secretion causes amplification of normal effects, plus other symptoms

Symptoms:
- High blood pressure
- Thinning or arms and legs, weight gain in torso

Question 5

List the growth hormone disorders

Answer 5

Dwarfism, Gigantism, Acromegaly

Question 6

Describe Dwarfism: the causes, what it is and the symptoms

Answer 6

Common causes: Genetic mutation or inheritance (eg. have short parents)

Hyposecretion disorder: reduced growth hormone secretion

Symptoms: short stature

Note: Dwarfism is an umbrella medical term for 100s of growth conditions that result in short stature

Question 7

Describe Gigantism: the causes, what it is and the symptoms

Answer 7

Common cause: pituitary gland tumour in childhood

Hypersecretion disorder: excess growth hormone secretion before long bones have stopped growing (epiphyseal plates have not yet fused)

Symptoms: Tall stature

Question 8

Describe Acromegaly: the causes, what it is and the symptoms

Answer 8

Common cause: pituitary gland tumour in early adulthood

Hypersecretion disorder: excess growth hormone secretion after long bones have stopped growing (epiphyseal plates have fused)

Symptoms: large and irregularly shaped extremities and characteristic facial features

Question 9

List the thyroid secretion disorders

Answer 9

Infantile hypothyroidism, Adult hypothyroidism, Simple Goitre, Graves disease

Question 10

Describe Infantile hypothyroidism: the causes, what it is and the symptoms

Answer 10

Common causes:
- Missing or poorly developed thyroid gland
- Poorly functioning anterior pituitary
- Lack of iodine in the mothers diet

Hyposecretion disorder: reduced secretion of thyroid hormone causes reductions of its normal effects, plus other symptoms

Symptoms include:
- Low metabolic rate
- Delayed growth and development

Most affected infants have few or no symptoms and can be treated with thyroid hormone. Early diagnosis is essential to prevent permanent damage.

Question 11

Describe Adult hypothyroidism: the causes, what it is and the symptoms

Answer 11

Common causes:
- Autoimmune disease
- Iodine deficiency in diet
- Surgical removal of thyroid gland

Hyposecretion disorder: reduced secretion of thyroid hormone causes reductions of its normal effects

Symptoms:
- Low metabolic rate; tiredness
- Sensitive to cold

Question 12

Describe Simple Goitre: the causes, what it is and the symptoms

Answer 12

Common cause: lack of iodine in diet

Hyposecretion disorder:
- Without iodine, the thyroid gland cannot make thyroid hormone
- Without thyroid hormone negatively feeding back, TRH and TSH get continually secreted
- Excess TSH causes the thyroid glands to swell

Symptoms: Enlarged thyroid gland = a goitre

Question 13

Describe Graves Disease: the causes, what it is and the symptoms

Answer 13

Cause: autoimmune disorder

Hypersecretion disorder: excess secretion of thyroid hormone causes amplifications of its normal effects, plus other symptoms

Symptoms:
- High metabolic rate; weight loss
- Sensitive to heat

Question 14

List the calcium homeostasis disorders

Answer 14

Hyperparathyroidism, Hypoparathyroidism

Question 15

Describe Hyperparathyroidism: the causes, what it is and the symptoms

Answer 15

Common cause: Parathyroid tumour

Hypersecretion disease: excess secretion of parathyroid hormone causes amplifications of its normal effects

Symptoms:
- Bones become soft, deformed and fragile
- Kidney stones (excess Ca2+ accumulates in kidney)

Question 16

Describe Hypoparathyroidism: the causes, what it is and the symptoms

Answer 16

Common cause: damaged parathyroid glands due to genetic or autoimmune disease

Hyposecretion disorder: reduced secretion of parathyroid hormone causes reduced plasma [calcium] - hypocalcaemia

Symptoms:
- Muscle tetant (tetanus); muscle spasms, cramps
- Seizures

Question 17

List the glucose homeostasis disorders

Answer 17

Type I Diabetes Mellitus, Insulin Resistance and Type II Diabetes Mellitus

Question 18

Describe Type I Diabetes Mellitus: the causes, what it is and the symptoms

Answer 18

Commons cause: beta islet cells in pancreas get destroyed by a virus or autoimmune disease

Hyposecretion disorder: reduced secretion of insulin causes symptoms related to chronically high plasma glucose (which can damage blood vessels and nerves), with inability for cells to use the glucose

Symptoms:
- Polyuria (excessive urine production)
- Polydipsia (excessive thirst)

Question 19

Describe Insulin Resistance and Type II Diabetes Mellitus: the causes, what it is and the symptoms

Answer 19

Common cause: Unhealthy lifestyle - inactivity, poor diet, obesity

• Hyposensitivity disorder (insulin resistance): insulin receptors on target cells become insensitive (resistant) to insulin due to chronically high insulin levels
• Hyposensitivity and Hyposecretion disorder (Type II Diabetes): As insulin resistance gets worse and the pancreatic beta islet cells wear out. This leads to progressively reduced insulin secretion.

Symptoms:
- Polyuria (excessive urine production)
- Polydipsia (excessive thirst)

Treatment and prevention: insulin, excersise, good diet