Endocrinology Flashcards
(342 cards)
What is the difference between a endocrine and an exocrine gland?
- Endocrine = glands ‘pour’ secretions into the bloodstream
- Exocrine = glands ‘pour’ secretions through a duct to site of action
What are the endocrine glands?
- Hypothalamus
- Pineal Gland
- Pituitary Gland
- Thyroid
- Parathyroid
- Thymus
- Adrenal
- Pancreas
- Ovaries
- Testes
What are the three types of hormone action?
- Endocrine: the hormone is distributed in blood and binds to distant target cells
- Paracrine: the hormone acts locally on adjacent cells
- Autocrine: the hormone acts on the same cell that secreted it
Give an example of a water soluble hormone.
Peptides e.g. TRH, LH, FSH
Are water soluble hormones stored in vesicles or synthesised on demand?
Water soluble hormones e.g. peptides are stored in vesicles
How do water-soluble hormones e.g. peptides get into a cell?
They bind to cell surface receptors
Give an example of a fat soluble hormone.
Steroids, e.g. cortisol
Are fat-soluble hormones stored in vesicles or synthesised on demand?
Fat-soluble hormones, e.g. steroids are synthesised on demand
Where are the receptors found for:
a) peptide hormones
b) steroid hormones
c) thyroid hormone
a) cell membrane
b) cytoplasm
c) nuclear receptors
Give 5 ways in which hormone action is controlled.
- Hormone metabolism - increased metabolism to reduce function
- Hormone receptor induction
- Hormone receptor down-regulation
- Synergism - combined effects of two hormones amplified, e.g. glucagon and adrenaline
- Antagonism - one hormone opposes other hormone, e.g. glucagon antagonises insulin
Name two hormones that reduce appetite.
Leptin and PPY
Name a hormone that increases appetite.
Ghrelin (GREEDY)
Where is parathyroid hormone released from? What is it released in response to? What is its role?
- Parathyroid hormone (PTH) is released from the four parathyroid glands
- It is released in response to low calcium serum. It is also released in response to low magnesium and high phosphate serum
- Its role is to increase the serum calcium concentration
What does a high serum calcium concentration cause the release of and from where?
A high serum calcium concentration causes the release of calcitonin from the c-cells of the thyroid gland
What are the functions of PTH?
- Increases calcium reabsorption at the kidney (so less excreted in urine) and decreases phosphate reabsorption
- Stimulates the kidneys to convert vitamin D3 into calcitriol, which is the active form of vitamin D that promotes calcium absorption from food in the small intestine
- Increases bone resorption (increases number of osteoclasts in bone, causing reabsorption of calcium from the bone into the blood)
What is calcium used in?
Calcium is used in neurotransmission and muscle contraction
What are the causes of hypocalcaemia?
- Vitamin D deficiency (secondary hyperparathyroidism)
- Hypoparathyroidism
- Pseudohypoparathyroidism (PTH resistance)
- Hyperventilation
- Drugs
- Malignancy
- Toxic shock
What will the PTH, calcium and phosphate levels be like in vitamin D deficiency (secondary hyperparathyroidism)? Is this an appropriate or innapropriate response?
- PTH high
- Calcium low (Vitamin D causes calcium and phosphate reabsorption)
- Phosphate low
What will the PTH, calcium and phosphate levels be like in hypoparathyroidism? Is this an appropriate or innapropriate response?
- PTH low
- Calcium low (as less PTH to reabsorb it)
- Phosphate high (as less PTH to lower it)
- Innapropriate response as low PTH is the problem
What will the PTH, calcium and phosphate levels be like in pseudohypoparathyroidism (PTH resistance)?
- PTH high
- Calcium low
- Phosphate high
- Appropriate response because the PTH resistance is the problem
What are the symptoms and signs of hypocalcaemia?
- Symptoms: CATS go numb - convulsions, arrhythmias, tetany, spasm and numbness
- Signs: Chevostek’s (tapping facial nerve induces spasm) + Trousseau’s (BP cuff 20 mm Hg above systolic for 5 minutes causes wrist to flex and fingers to draw together)
What are the investigations for hypocalcaemia?
- Corrected calcium levels - done using serum calcium and serum albumin
- ECG (long QT interval)
- Parathyroid function
What is the management for hypocalcaemia?
- 10ml calcium gluconate/chloride 10% slow IV
- Oral calcium
- Vit D
What are the complications of hypocalcaemia?
Seizure, cardiac arrest (decreases heart rate and contractility) - a medical emergency!

















































