ENCDOCRINOLOGY Flashcards
Location of the hypothalamus:
Location of the third ventricle
What do magnocellular neurons secrete in the posterior pituitary?
- Secrete ADH and oxytocin (from either supraoptic nucleus OR paraventricular nucleus
What is the blood supply of the ANTERIOR PITUITARY
Internal carotid artery which goes into the hypophyseal arteries–> form median eminence –> divides into veins (portal veins) –> come down and supply anterior pit.
What is the blood supply of the posterior pituitary?
- MIddle hypopyseal artery
- Inferior hypophyseal arteries
Where does the pituitary gland sit?
- In pituitary fossa
What is the pituitary gland surrounded by?
- Carnevous sinus (contains carotid arteries), cranial nerves, Sphenoid sinus
What will a tumor in the pituitary gland affect?
- The surrounding structures, puts pressure on the optic chiasm–> double vision
What does a tumor in the pituitary gland putting pressure on the canernous sinuses cause?
Bad headaches
What can a pituitary tumor that presses LATERALLY on the cranial nerve (oculomotor) cause?
- Transmission can be affected (lesions)
- Eye muscles don’t work properly
Where does the posterior pituitary develop from?
- Develops from BRAIN (buds off and moves down)
Where does the anterior pituitary develop from?
- Develops from roof of mouth and moves UP during development
What are the 5 cell types from the anterior pituitary and what do they secrete?
SOMATOTROPHS--> Growth Hormone (GH) LACTOTROPHS--> Prolactin (PRL) THYROTROPHS--> TSH (thyroid stimulating hormone) GONADOTROPHS-->FSH AND LH CORTICOTROPHS--> ACTH
Where are the parvocellular neurones and where do their nerve terminals go?
- Within paraventricular nucleus area of hypothalamus
- Nerve terminals go TO median eminence
Is the posterior pituitary a gland?
- NO! It is an extension of the hypothalamus (embryo-buds off from brain)
When are ADH or oxytocin released in terms of APs?
- If the nerves ARE electrically stimulated (AP)
Where are oxytocin and ADH made?
- Paraventricular nucleus and supraoptic nucleus clusters
- WIthin cell bodies of neurones
- Then transported DOWN axon and stored in axon terminal
What is oxytocin (what type of structure) and what is it inoolved in?
- 9aa peptide
- Involved in lactation
- Involved in suckling (positive feedback via mechanoreceptors) –> oxytocine released
- Labour (positive feedback) -stretch recepotrs–> signals to brain and hypothalamus
What does prolactin cause?
- Milk production
What does oxytocin casue in terms of feeding?
- Milk let down
Which two things is ADH most sensitive to?
- Change in plasma osmolarity (1% changes it is sensitive to)
- Change in BP (10-15% changes it is sensitive to) –> baroreceptors in aortic arch and carotid bodies + low pressure vol. receptors in atria and pulm venous system in chest.
Which receptors does ADH act on in kidney and blood vessels and what do these receptors do when ADH is bound?
Kidney= V2 receptors
Blood vessels= V1
- These receptors when activated cause more aquaporins to migrate to renal tubule membranes
Is the secretion of anterior pituitary hormones a balance between positive and negative hypothalmic influences?
- YES!
Is there a hypothalmic stimulator and inhibitor for each anterior pituitary hormone?
- YES!
What is hyperplasia?
- Increase in the number of cells