Pituitary, pancreatic and thyroid endocrinology

Question 1

what hormones are secreted from the anterior pituitary gland?

Answer 1

• TSH
• GH
• ACTH
• Prolactin
• LH
• FSH

Question 2

what hormones are secreted from the posterior pituitary gland?

Answer 2

• ADH (vasopressin)

- Oxytocin

Question 3

Where are the hormones made that are secreted from the anterior pituitary gland?

Answer 3

it has endocrine cells that make and store the hormones

Question 4

where are the hormones made that are secreted in the posterior pituitary gland?

Answer 4

Cell bodies in the supraoptic and paraventricular nuclei make the hormone and vesicles travel down the axons and are stored in the PPG awaiting exocytosis

Question 5

what hormones are made at response? what are released at response

Answer 5

made at response = steroid hormones

released at response = peptide hormones

Question 6

what is the action of ACTH? what cell synthesises it?

Answer 6

causes the production of cortisol in the zona fascicula in the adrenal cortex

synethesised in basophil cells

Question 7

what is the action of TSH in males? what cell synthesises it?

Answer 7

acts on the thyroid gland to produce thyroxinne - triiodthyroninne - T3 and tetraidothyroninne

synthesised by basophil

Question 8

what is the action of Growth hormone? what cell synthesises it?

Answer 8

it acts on the liver to produce IGF-1 which causes growth of body tissue

synthesised by acidophils

Question 9

what is the action of prolactin? what cell synthesises it?

Answer 9

it acts on the breast tissue to stimulate milk production

synthesised by acidophils

Question 10

what is the action of FSH in females? what cell synthesises it?

Answer 10

stimulates the maturation of follicular cells

synthesised by basophils

Question 11

what is the action of LH in females? what cell synthesises it?

Answer 11

• supports theca cells
• stimulates oestrogen production
• LH surge causes ovulation
• stimulates the corpus luteum to produce porgesterone

synthesised by basophils

Question 12

what is the action of LH in males? what cell synthesises it?

Answer 12

stimulates lydeig cells to produce testosterone

synthesised by basophils

Question 13

what is the action of FSH in males? what cell synthesises it?

Answer 13

stimulates steroli cells to produce sperm.

synthesised by basophils

Question 14

what is the action of oxytocin? what cell synthesises it?

Answer 14

• causes uterine contractions
• causing lactation in breast tissue
• know as the love molecule encourages caring behaviour

synthesised mainly in the paraventricular nuclei

Question 15

what is the action of ADH (vasopressin)? what cell synthesises it?

Answer 15

• causes the insertion of vesicles containing aquaporin 2 channels in the apical membrane of principal cells in the nephrin collecting duct
• systemic vasoconstrictor

synthesised mainly in the supraoptic nuclei

Question 16

what are the cell types in the pancreatic islets of langerhans? what do each of them secrete? in what proportions?

Answer 16

alpha cells - glucagon - 20%
beta cells - insulin - 70%
delta cells - somatostatin - 8%
2% something else that i don’t care about

Question 17

what is the mechanism of insulin secretion?

Answer 17

• excess glucose enters the beta islet cells
• glucose is metabolised and ATP is produced
• ATP K+ channels to close causing depolarisation of the cell
• depolarisation causes Ca2+ voltage gated channels to open
• Ca2+ influxes into the cell causing vesicles containing insulin to be exocytosised

Question 18

what is the action insulin has at cells?

Answer 18

• insulin binds to receptors on muscle and fat cell plasma membranes
• causes an intracellular signalling cascade (probs cAMP)
• this causes vesicles containing GLUT-4 channels to be inserted in the plasma membrane
• glucose then enters the cells

muscle cell - stored as glycogen and used for protein synthesis

fat cells - used for fatty acid synthesis

Question 19

what is the bodies physiological response to a decreased blood glucose level?

Answer 19

• lowered blood glucose stimulates alpha cells in the islets of langerhans to secrete glucagon
• glucagon increases the breakdown of glycogen and increases gluconeogensis

Question 20

describe the anatomy of the thyroid gland?

Answer 20

• 2 lobes L + R connected by an isthmus and sometimes a pyramidal lobe is present
• 2 arteries superior and inferior
• 3 veins superior, middle and inferior

Question 21

what is the function of T3 and T4? how does it achieve this?

Answer 21

they increase metabolic rate by increasing gene transcription and mRNA production

they have different effects on different tissues

Question 22

what are some effects of T3 and T4 on tissues?

Answer 22

CVS

• increase CO
• increase HR
• increase respiration

Metabolism

• increase O2 consumption
• increase glucose absorption,glycolysis gluconeogenesis, lipolysis
• increase protein synthesis
• increase BMR

-stimulates CNS development

Question 23

what form of thyroid hormone is more metabolically active? which one is produced more?

Answer 23

T3 -triiodthyroninne is more metabollically active

T4 - thyroxinne - tetraidothyroninne is produced more but cleaved at the cell before entering

Question 24

briefly describe how thyroid hormone is produced.

Answer 24

• Iodine is actively transported into the folicular cell with Na+ using a symporter (Na+ is transported back using Na+/K+ antiporter)
• Iodine is then transported into the colloid via pendrin a I-/Cl- antiporter
• Iodine is then turned into a Iodine radical molecule via the action of peroxidase
• the iodine radical can then bind to tryosine rings that are attached to a thyroglobulin back bone (thyroglubin is produced in the folicular cell and transported into the colloid)
• the thyroglobulin and now attached T3 or T4 reenter the cell and lysosome break off the thyroglobulin back bone

T3 and T4 are transported through the blood on plasma proteins are they are lipid soluble