Hormones - Introduction Flashcards
Define haemocrine
A chemical messenger secreted by a gland that travels in the blood to a distant target.
Define paracrine
A hormone that has an effect only in the vicinity of the gland secreting it e.g a neighbouring cell
Define autocirne
A cell produced substance that has an effect on the cell from which it was secreted
Define solinocrine
A hormone secreted into the lumen of an organ e.g GI tract, urogenital etc
What is ketoacidosis a sign of?
Hyperglycemia therefore diabetes
What can cause hypoglycemia?
Insulinoma (tumour on the beta cells of the pancreas)
What is thyrotoxicosis?
Excess production of thyroxine
What causes an excess production of thyroxine?
Autoimmune activation of the thyroid gland
What does excess production of thyroxine do to the body - explain the symptoms.
Sensitises the body to adrenaline, giving symptoms of tachycardia, weight loss, heat intolerance and tremours.
What is hypothyroidism?
Lack of production of thyroxine
What causes hypothyroidism?
Autoimmune disease where the thyroid is destroyed
What does hypothyroidism lead to?
Goitre and weight gain.
How do you detect hypothyroidism?
Test TSH and T3 and T4 levels in the blood.
TSH high
T3 and T4 levels low
How would you detect thyrotoxicosis?
Test TSH and T3 and T4 levels in the blood.
TSH levels low
T3 and T3 levels high
What are steroid hormones synthesised from?
Cholesterol
What are the two main steroid hormones produced by the adrenal gland?
Cortisol
Aldosterone
What conditions cause the body to release cortisol?
Stress and low blood glucose
Where in the adrenal gland is cortisol produced?
Zona fasciculata
What type of hormone is cortisol?
Glucocorticoid steroid hormone
What type of hormone is aldosterone?
Mineralcorticoid steroid hormone
Where in the adrenal gland is aldosterone produced?
Zona glomerulosa
What is the main function of aldosterone?
Increase sodium retention in the kidney
What type of receptors do aldosterone and cortisol bind to and why?
Intracellular receptors as they are steroid hormones they can diffuse through the cell surface membrane.
What causes cushings syndrome?
Overproduction of ACTH or a tumour in the adrenal gland which leads to excessive cortisol production.
What are the symptoms of cushings syndrome?
Obesity Diabetes due to cortisol raising blood glucose levels Hypertension Thin skin Muscle weakness
What is Addisons disease and how is it caused?
Hypoadrenalism caused by autoimmune destruction of the adrenal gland.
What are the symptoms of Addisons disease?
Weight loss
Dizziness
Weakened immune system
Strange pigmentation of the skin
What controls ACTH production?
CRH
Where does CRH act?
Corticotrophs in the anterior pituitary
What is the leptin feedback loop?
- Fat cells produce leptin
- Leptin decrease food intake
- Less food intake means fat levels decrease
- Decreased fat levels means less leptin produced
- Less leptin produced = eat more, fat levels increase
Define diurnal
During the day
Was is goitre?
Swelling of the neck due to enlargement of the thyroid.
