Pituitary, Adrenal, Thyroid Flashcards
What is the MOA of steroidal hormones
1) move into membrane
2) Binds to intracellular receptor
3) Increases transcription factors and causes change in mRNA
What is the MOA of non steroidal hormones
1) Binds to cell surface receptor
2) cAMP signalling pathway
How are the hypothalamus and posterior pituitary gland linked
Neuronal pathways
What is function of hypothalamus
Controls release of hormone signals to anterior and posterior pituitary
How is the hypothalamus and anterior pituitary linked
Vascular links
What hormones are released by the posterior pituitary
Oxytocin
Vasopressin
What does oxytocin do
Child birth muscle contraction
Social development and behaviours
Secretes milk during breastfeeding
What does vasopressin do
1) V2 receptor = ADH that increases water permeability and increases reabsorption
2) V1 receptor = Binds to smooth muscle and controls contractions
How are hormones released from the posterior pituitary
Hypothalamus secretes hormones in vesicles
Transported down neuronal pathway axons
Stored in neuronal terminals in pituitary
Becomes excitable and released into circulation
What hormones does the anterior pituitary released and summarise what they do
1) Growth Hormome - Stimulates IGF-1 from liver to increase peripheral growth in tissue
2) Thyroid stimulating - stimulated production of T3, T4
3) Adrenocorticotropic - Stimulates adrenal cortex growth
4) Follicle stimulation - reproductive processes
5) Luteinizing - helps reproductive cycle and menstruation
6) Prolactin - regulates lactation and breast production
Outline the three hormone sequence
1) Hypothalamus releases hormones
2) Stored in anterior pituitary gland
3) Released into bloodstream via capillary diffusion transportation
4) Gland (ie, thyroid)
5) Hormones released from gland and targets the desired organH
How is the regulation of hormones controlled?
1) Negative feedback loops - too much hormone = stop in production
2) Hypothalamus
What is the target for growth hormone
Somatostatin receptors
What is released from the andrenal glands
Aldosterone
Corticosteroids
Androgens
What hormone regulates aldesterone release
Adrenocorticotropic
What is the function of the mineralocorticoid aldesterone
Promotes Na+ reabsorption via Na+/K+ channels
Increase blood volume due to osmosis
Distal convoluted tubule and collecting ducts
What are the effects of cortisol on the body
1) Increase gluconeogenesis, glucose cell uptake and blood glucose
2) Anti-inflammatory/ immunosupressive
3) Stress
Summarise how cortisol is secreted
1) Hypothalamus secreted CRF hormone
2) Adrenocorticotropic hormone released by anterior pituitary
3) Adrenal cortex stimulated
4) Releases cortisol
What causes cushings syndrome
Increased cortisol release via CRF, ACTH
Hyperglycaemia, moonface, poor wound healing
Give examples of steroid medications
Prednisolone, beclomethasone, hydrocortisone
What are the systemic side effects of long term steroid use
1) Adrenal suppression
2) Immunosuppression - increased infections
3) Psychiatric - mental health and nightmares
What role does the hypothalamus have in secreting thyroid hormone
1) Hypothalamus -releases TRH
2) Pituitary gland (adrenal) releases TSH
3) Allows thyroid to make and release T3 and T4
Describe anatomy of thyroid structure
1) Follicular cells - Product thyroid hormone and store it
2) Thyroglobulin - Carries Iodine, tyrosine, calcitonin
3) Parafollicular cells - Secrete calcitonin
What is the sequence of the 3 step process used to produce T3 and T4
1) Oxidation
2) Organification
3) Coupling
What stimulates transfer if iodide ions into the blood
TSH
How are iodine ions transported from blood to thyroid
Na+/ I- transporter
What enzyme facilitates the conversion id iodide ions to iodine
Thyroperoxidase through oxidation
What is organification in thyroid production
1) Thyroglobulin + I2 (oxidised I-)
2) Produces: MIT and DIT
How is T3 and T4 transported back into the blood from where?
1) Transported from follicular lumen
2) uses endocytosis to transport back to blood
3) Lysosomes break down vesicles
4) T3, T4 released
What is coupling in thyroid production
3) MIT + DIT = T3
4) DIT + DIT = T4
What are the symptoms of HYPO-thyroidism
weakness,
fatigue,
weight gain
hair loss
Name a disease associated with HYPO-thyroidism
Hashitmotos - autoimmune where thyroid is destroyed
due to extra TSH release
What would you expect to see in levels of TSH, T3, T4 in someone with HYPO-thyroidism
1) INCREASE TSH
2) DECREASE T3, T4
What would you expect to see in levels of TSH, T3, T4 in someone with HYPER-thyroidism
1) DECREASE TSH
2) INCREASE T3, T4
What is the pharmaceutical approach for HYPO-thyroidism
Levothyroxine (T4 structure)
25-50mcg daily
What are the symptoms for HYPER-thyroidism
Sweating
anxiety
tremor
eye problems
Name 3 diseases associated with HYPER-thyroidism and summarise them
1) Graves - Immune system creates antibodies to mimic TSH and act as the pituitary gland to secrete more thyroxine
2) Toxic nodular goitre - INCREASE in follicle formation, more follicles = more iodine to be converted into thyroxine
3) Tumours - Benign tumours = can secrete more TSH
When is a beta blocker used in thyroid problems
HYPER-thyroidism
Relief of sympathetic symptoms: Sweating, tremor, anxiety
Propranolol
Gives some Medicinal approaches to HYPER-thyroidism
1) Carbimazole - Inhibits thyroidperoxidase
(first line)
2) Propylthiouracil - inihibts thyroidperoxidase
Red flag symptoms of carbimazole
Lowers immune system and blood cell count
