Lecture 2

Question 1

Where does the hypothalamus sit?

Answer 1

sella turcica in the skull

Question 2

What is the clinical relevance of the position of the pituitary?

Answer 2

Encased in skull, if enlargement/inflammation/tumour, can only grow up, pushing into optic chiasm = visual disturbances

Question 3

What is suggested by endocrine imbalances after a road traffic accident?

Answer 3

infundibulum fracture

Question 4

What is the neurohypophysis and what is its role?

Answer 4

Posterior pituitary gland (downgrowth from brain including nerve fibres), secretes ADH and Oxytocin

Question 5

Name two HPA hormones that overlap in activity and explain why.

Answer 5

In oxytocin and vasopressin (ADH), 7 of 9 amino acids are identical so they influence some of the same receptors

Question 6

Discuss the synthesis of ADH and oxytocin?

Answer 6

Synthesized inactive in neurones of hypothalamus (supraoptic nuclei and paraventricular nucleus) and stored in posterior pituitary where they are converted to active in as they are released into bloodstream.

Question 7

Describe the secretion and action of ADH.

Answer 7

Secretion influenced by plasma osmolarity, influence v2 receptors, causing translocation of aquaporins allowing water reabsorption.. Also stimulate V1 receptors, causing vasoconstriction

Question 8

When is oxytocin important?

Answer 8

pregnancy (production increases but so does oxytocinase production), parturition/birth (uterine smooth muscle contraction), lactation (nipple smooth muscle contraction), increased bonding (recognition) between mother and child

Question 9

What condition is caused when ADH is not produced and what are its symptoms?

Answer 9

Diabetes insipidus, thirst, large levels of urine produced, very dilute urine

Question 10

How much urine is passed per day in most people and in those with ADH deficiency?

Answer 10

750 mL in most people. 12 L in people with ADH deficiency.

Question 11

What is the name of the condition where excess ADH is secreted?

Answer 11

SIADH: Syndrome of inappropriate ADH (fluid accumulation occurs)

Question 12

What stimulates oxytocin secretion?

Answer 12

stimulation of genitals and nipples, nervous signal sent to pituitary, post pituitary releases oxytocin, travels through blood stream, arrives at breast, delay of about 2 min. Paired stimulus baby crying (pavlov theory)

Question 13

Describe the cycle of oxytocin release

Answer 13

Oxytocine acts on G-Protein linked receptor causes calcium influx, smooth muscle stretch, action (expulsion of milk/foetus) producing further stimulation leading to more oxytocin secretion.

Question 14

Describe the origin of the anterior pituitary and another name it has.

Answer 14

adenohypophysis: upgrowth from roof of mouth into brain

Question 15

What hormones are secreted by the anterior pituitary?

Answer 15

Growth Hormone, Prolactin, Thyroid Stimulating Hormone, Adrenocorticotrophic Hormone, Follicle Stimulating Hormone, Luteinising Hormone

Question 16

Where are the hormones secreted by the anterior pituitary synthesized?

Answer 16

Also ant pituitary, by separate cells. TSH by thyrotrophe cells. Adrenocorticotrophic hormone by corticotrophe cells, FSH by gonadotrophe cells