Endocrine system Flashcards by Lili Prolze

What are the 8 endocrine glands?

Pituitary gland
Pineal gland
Thyroid gland
Thymus gland
Adrenal gland
Pancreas
Ovaries
Testis

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What are hormones?

Chemical signals produced in endocrine glands or tissues that travel in the bloodstream to cause an effect on other tissues

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What is cortisol?

A steroid hormone that is released from the adrenal gland

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What are the actions of cortisol?

Increased protein breakdown in muscle (catabolic)
Increased lipolysis in fat (catabolic)
Increased gluconeogenesis in liver (catabolic)
Resistance to stress
Anti-inflammatory effects
Depression of immune system

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What is Cushing’s syndrome?

Chronic excessive exposure to cortisol

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What is the external cause of Cushing’s syndrome?

Prescribed glucocorticoids (most common cause)

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What are the endogenous causes of Cushing’s syndrome?

Benign pituitary adenoma (tumour)
Excess cortisol produced by adrenal tumour
Non pituitary-adrenal tumours producing ACTH (very rare)

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What are the signs and symptoms on Cushing’s syndrome?

Plethoric moon-shaped face
‘Buffalo hump’
Abdominal obesity
Purple striae
Acute weight gain
Hyperglycaemia
Hypertension

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What is Addison’s disease?

Chronic adrenal insufficiency

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What are the causes of addison’s disease?

Main cause at the time of discovery was a complication of tuberculosis
Most common cause now is destructive atrophy from autoimmune disease - exact reason for autoimmunity is unknown
Rarer causes include fungal infection, adrenal cancer, adrenal haemorrhage

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What are the signs and symptoms of Addison’s disease?

Postural hypotension
Lethargy
Weight loss
Anorexia
Increased skin pigmentation
Hypoglycaemia

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Where is the thyroid gland?

Lies against and around front larynx and trachea
Below thyroid cartilage
Isthmus extended from 2nd to 3rd rings of the trachea
2 lobes joined by isthmus
‘Bow tie’ shape and location
Parathyroid and thyroid are distinct glands

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What are the 2 main hormones produced by the thyroid gland?

T3 - tri-iodothyronine
T4 - thyroxine

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Secreted directly from the thyroid gland
Influences body metabolism

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Converted into T3 in tissues and cells
Iodine is essential for the formation of T3 and T4
TSH stimulates the release of T3 and T4

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What are the functions of T3 and T4?

Essential for normal growth and development, especially of skeletal and nervous system
Most other organs and systems are influenced by thyroid hormones - heart, skeletal muscles, skin, digestive organs, reproductive organs

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What is Hypothyroidism?

Underactive thyroid
Not enough thyroxine (T4) is produced for the body’s needs
Most common

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What is hyperthyroidism?

Overactive thyroid
Too much thyroxine is produced for the body’s needs

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What is a goitre?

Enlargement of the thyroid gland
May accompany either hypo or hyperthyroidism but not necessarily present in either
Develops when the thyroid gland is overstimulated

What are the causes of a goitre?

Failure of thyroid gland
TSH or TRH deficiency
Inadequate dietary supply of iodine
Radioactive iodine
Autoimmunity
Post surgery
Congenital
Anti-thyroid drugs

What are the symptoms associated with a goitre?

Obesity
Lethargy
Intolerance to cold
Bradycardia
Dry skin
Slope is
Hoarse voice
Constipation
Slow reflexes
Low T3 and T4
Elevated TSH

What is Hashimoto’s disease?

Autoimmune disease resulting in destruction of thyroid follicles
Leads to hypothyroidism
Most common disease of the thyroid gland
5 times more common in women than in men

What are the signs of Hashimoto’s disease?

Low T3
Low T4
Elevated TSH
Goitre may or may not be present

What is the treatment for Hashimoto’s disease?

Oral Thyroid hormone
T4 used since longer half life

What are the causes of hyperthyroidism?

Autoimmune Graves’ disease Toxic multinodular goitre Solitary toxic adenoma Excessive T4 or T3 therapy Drugs - amiodarone Thyroid carcinoma

What are the symptoms of hyperthyroidism?

Weight loss Irritability Heat intolerance Tachycardia Fatigue, weakness Increased bowel movements Sweating and tremor Breathlessness

What is graves’ disease?

Autoimmune disease resulting in hyperthyroidism Caused by production of thyroid stimulating immunoglobulin (TSI) TSI continuously stimulates thyroid hormone secretion (outside normal negative feedback control)

What are the symptoms of graves’ disease?

Increase in BMR Excessive sweating Decrease in body weight Muscle weakness Heart palpitations Bulging eyes

What is melatonin?

Hormone linked to sleep Darkness stimulates release Light inhibits secretion Secreted into blood and enters CSF Excited in urine Production decreases with age

What are the implications of melatonin for patients?

Noisy bright wards decrease secretion May need supplements Out of sync circadian rhythm - poor quality or life, poor mental health , poor physical health decrease in bowel movements Links to diabetes Links to obesity

What are the 5 tissues comprising the MSK system?

Bones Ligaments (attaching bone to bone) Cartilage (protective gel like substance lining joints and intervertebral disks) Skeletal muscles Tendons (attaching muscles to bone)

What is Catabolism?

The set of metabolic pathways that breaks down molecules into smaller units that are either oxidised to release energy or used in other anabolic reactions

What is anabolism?

The set of metabolic pathways that construct molecules from smaller units, these reactions require energy, known also as an endergonic process

What impact does glucagon have on muscles?

Promotes skeletal muscle wastage to supply amino acids for energy (gluconeogenesis)

What impact does cortisol have on muscles?

Secreted by adrenal glands Helps to deal with stress Increases protein breakdown Decreases protein synthesis

What impact does adrenaline have on muscles?

Stimulate sympathetic nervous system Breaks down muscle mass by using ATP and fuel stores in preparation for exercise

What impact does testosterone have on muscles?

Increases growth hormone release

What impact does oestrogen have on muscles?

Increases muscle metabolism Reduced muscle break down Helps repair muscles

What impact does Insulin-like Growth Factor-1 have on muscles?

Released from liver Signal to cells to undergo hypertrophy and cell division

What are osteoblasts?

Bone-building cells - they deposit new bone tissue around themselves, they eventually become trapped in tiny pockets in the growing bone, and differentiate into osteocytes

What are osteocytes?

Mature bone cells - they do not divide and are responsible for bone formation and calcium homeostasis

What are osteoclasts?

Bone-reabsorbing cells - breakdown bone releasing calcium and phosphate. As new bone cells are made, old ones are destroyed by osteoclasts

What impact does oestrogen have on bone?

Regulates metabolism Promotes activity of osteoblasts Prevents bone cell death by osteoclasts

What is osteoporosis?

When the skeletons loses mineral density, the structure becomes thin and unable to take normal weight, leaving bones that break easily

What are the risk factors for osteoporosis?

Gender Heredity Age Fracture history Medical conditions Medications

What conditions can cause bone loss?

Alcoholism Cancers Coeliac disease Crohn’s disease Cushing’s disease Diabetes Type 2 Eating disorders Hyperthyroidism Hypogonadism Liver disease Malabsorption Rheumatoid arthritis