Applied Endocrine And MSK Flashcards
What is the role of the endocrine system?
- The endocrine system is a collection of glands located throughout the body
- Hormones are chemical signals produced in the endocrine glands and travel in the blood stream
- Apart from the endocrine glands other organs and tissue also release important hormones: heart, liver, stomach, placenta, adipose tissue, kidneys
What is cortisol and what does it do?
Cortisol is a steroid hormone which is released from the adrenal gland
This actions are:
»> increase protein breakdown in muscle
»> increase lipolysis in fat
»> increase gluconeogenesis in the liver
»> increased resistance to stress
»> has anti-inflammatory effects
»> depression of the immune system
Cushing syndrome
This is chronic excessive exposure to to cortisol
External causes»_space;> prescribed glucocorticoids»_space;> most common endogenous causes»_space;> rare
- benign pituitary adenoma (tumour)
- excess cortisol is produced by an adrenal tumour
- non pituitary-adrenal tumours producing ACTH
Signs and symptoms…..
…..plethora moon-shaped face
…..”buffalo hump”
…..abdominal obesity
…..purple striae
…..acute weight gain
…..hyperglycaemia
…..hypertension
Addisons disease
This is due to chronic adrenal insufficiency
- main cause used to be due to a complication of tuberculosis
- main cause now is due to destructive atrophy from autoimmune response
- this disease affects more women than men
- the reason for the autoimmunity is unknown
- rarer causes»_space;> fungal infection, adrenal cancer, haemorrhage
Signs and symptoms…..
…..postural hypotension
…..lethargy
…..weight loss
…..anorexia
…..increase skin pigmentation
…..hypoglycaemia
Thyroid gland
- lies against and around the front larynx and trachea
- lies below the thyroid cartilage»_space;> Adam’s apple
- isthmus extends from 2nd to 3rd rings of trachea
- 2 lobes joined by isthmus»_space;> bow tie shape
- parathyroid and thyroid are distinct glands
The thyroid gland produces two main hormones:
1) T3 = tri-iodothyronine
2) T4 = thyroxine - T3 is secreted directly from the thyroid gland
- T4 is converted to T3 in tissues and cells
- T3 influences body metabolism
Formation and release of T3 and T4
Iodine is essential for the formation of T3 and T4
»> thyroid gland selectively takes up iodine from blood
»»» TSH released from pituitary gland stimulates the release of T3 and T4 into blood
Function of T3 and T4
T3 and T4 are 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
All influenced by T3 and T4, evident when thyroid is under or over active
What can go wrong with the thyroid?
Hypothyroidism - under-active thyroid»_space;> not enough T4 is produced for the body’s needs»_space;> most common disorder
Hyperthyroidism - over-active thyroid»_space;> too much T4 is produced for the body’s needs
Goitre
May accompany either hyper or hypothyroidism
Develops when the thyroid gland is overstimulated
Causes…..
…..failure of thyroid gland
…..TSH/TRHH deficiency
…..inadequate dietary supply of iodine
…..radioactive iodine
…..autoimmunity
…..post-surgery
…..anti-thyroid drugs
Symptoms
»> obesity»_space;> lethargy»_space;> intolerance to cold»_space;> bradycardia»_space;> dry skin»_space;> Alopecia»_space;> hoarse voice»_space;> constipation»_space;> sow reflexes»_space;> low T3 and T4»_space;> elevated TSH
Hashimoto’s disease
- an autoimmune disease resulting in destruction of thyroid follicles. Leads to hypothyroidism
- most common disease of the thyroid gland
- this condition is 5x more likely in women than men
- goitre may or may not also be present
Plasma
»> low T3 and T4»_space;> elevated TSH
Treatment
»> oral thyroid hormone»_space;> T4 used since longer half-life»_space;> normally 50-200 micrograms/day in a single dose
Hyperthyroidism
- autoimmune disease resulting in hyperthyroidism
- caused by production of thyroid stimulating immunoglobulin (TSI)
- TSI continuously stimulates thyroid hormone secretion
- outside normal negative feedback pathways
Causes
»> autoimmune Graves’ disease
»> toxic multinodular goitre
»> solitary toxic adenoma
»> excessive T3 or T4 therapy
»> drugs-amiodrone
»> thyroid carcinoma
Pineal gland
Responsible for the formation and secretion of melatonin
- darkness stimulates the release of this and light inhibits its secretion
- melatonin is secreted into blood and enters the CSF
- melatonin is excreted in urine
- the production of melatonin decreases with age
Implications for patients
»> noisy bright wards»_space;> supplements»_space;> out of sync cardiac rhythm»_space;> decreased quality of life»_space;> poor physical and mental health»_space;> decreased bowel movements»_space;> links to diabetes and obesity
What are the 5 basic tissues comprising the the MSK
1) bones
2) ligaments
3) cartilage
4) skeletal muscle
5) tendons
Hormonal impacts on muscles
Differences between catabolism and anabolism
Catabolism»_space;> set of metabolic pathways that break down molecules into smaller units that are either oxidised to release energy or used in other anabolic reactions
Anabolism»_space;> set of metabolic pathways that construct molecules from smaller units in reactions that require energy known as an endergonic process
Hormonal impact of bones
Oestrogen
- regulates bone metabolism
- promotes activity of osteoblasts
- revenge bone cell death by osteoclasts
