Flashcards in Endocrinology and cell signalling Deck (62)
What disease will someone with Hypoadrenalism suffer from?
What is Cushsings syndrome?
Excess glucocorticoids - cortisol
Name 4 hormones which are synthesised in the Anterior Pituitary gland
Follicle stimulating hormone
Thyroid stimulating hormone
Give 5 functions of cortisol
Maintain muscle function
Decrease bone function
Decrease connective tissue
Inhibit inflammatory and immune response
Maintain cardiac output
Facilitate maturation of foetus
Increase glomerular filtration
Modulate emotional tone
List 3 things which could cause excess hormone production
Neoplasm in endocrine gland
Hyperplasia of endocrine tissue
List 4 things which could cause a deficit in hormone production
Autoimmune attack of gland
Under development of gland
Give 2 examples of peptide hormones
How are steroid hormones synthesised?
Hydrolysis of esters or uptake of cholesterol
Cholesterol converted to pregnenalone by C P450 in mitochondria
Pregnenalone is processed in smooth ER
Then diffuses out of the cell
Which cells generally have autocrine signalling as a common feature?
Production of growth hormones perpetuates proliferation
What 3 effector mechanisms can be used to change cell behaviour?
Alter gene transcription
Alter ion balance across membrane
Alter level of enzyme activity
Which residues does phosphorylation mostly occur on?
Serine and threonine
Describe the phototransduction pathway?
Photon binds to rhodopsin receptor
cGMP phosphodiesterase converts cGMP to GMP
Closes Na channels and changes membrane potential
In order for a molecule to diffuse across a membrane, what must occur?
Solute must dissolve in the hyrophobic core of the membrane
What are GLUT transporters?
Glucose transported into cell and then converted to glucose 6 phosphate in order to maintain concentration gradient
What is an endocrine gland?
Gland which secretes hormones directly into the blood stream
What is an exocrine gland?
Gland which secretes chemicals via a duct
What tissues have endocrine function?
What are 3 types of hormones?
Modified amino acids
Describe steroid hormone synthesis
Hydrolysis of esters and cholesterol uptake
Conversion of cholesterol to pregnenalone in mitochondria
Processing of pregnenalone in smooth ER
Diffusion from the cell
Describe protein and peptide hormone synthesis
Translation on rough ER
Post translational modification in Golgi
Packaging into secretory vesicles which are stored and ready for release when signalled
How is parathyroid hormone synthesised?
Pre-pro-PTH with signal, pro, biologically active and c terminal fragments
Cleaved twice to form active PTH
How is ACTH formed?
Formed as propriomelanocortin which is cleaved into ACTH, amino terminal fragment and B-lipotropin
Give an example of a tyrosine kinase receptor system
What is the only example of a positive feedback loop in endocrinology?
LH surge in menstruation caused by oestrogen levels
Describe the anatomy of the thyroid gland
2 lateral lobes and an isthmus
In front of trachea
Large: 5cm long, 2-3cm deep, 3-4cm wide, 15-20g
What hormones does the thyroid gland make?
Basal metabolic rate: thyroxine (T4), tri-iodothyronine (T3)
Calcium homeostasis: calcitonin
What are T3 and T4 derived from?
4 iodine molecules in T4
3 iodine molecules in T3
Describe the thyroid gland microstructure
Made of follicles: follicular cells containing colloid, parafollicular cells (c cells)
Follicular cells produce T3 and T4
Parafollicular cells produce calcitonin
What are the steps of thyroid hormone synthesis?
Thyroglobulin synthesis (from tyrosine) - colloid
Uptake and concentration of iodide (I-)
Oxidation of iodide to iodine (Thyroid peroxidase, luminal membrane of follicular cell)
Iodination of thyroglobulin to MIT and DIT mono-, di-iodotyrosine
Conjugation of 2 iodinated tyrosine molecules to form T4 or T3