Pineal Gland & Endocrine Pancreas

Question 1

Endocrine vs Exocrine Pancreas blood supply

Answer 1

pancreatic islet = insuloacinar portal system
pancreatic acini = islet capillary + acinar vascular system

Question 2

Major cell types in Islets of Langerhans

Answer 2

Alpha = glucagon = ↑blood glucose (periphery)
Beta = insulin = ↓blood glucose (not periphery)
Delta = somatostatin = inhibit insulin/glucagon release

Question 3

Glucagon and Insulin release

Answer 3

• high glucose level = pre-proinsulin –> proinsulin
• remove C-peptide in secretory vesicle = mature insulin
• insulin released taken up by cells to get glucose in
• glucagon breakdown glycogen in liver (release to increase glucose)

Question 4

Pineal Gland Cells

Answer 4

• pinealocytes (nuclei with euchromatin)
• interstitial cells (dark nuclei)
• brain sand (calcified concretions)

Question 5

Pineal Gland Function

Answer 5

• regulate circadian rhythms
• pinealocytes make melatonin from tryptophan
• melatonin released into capillaries
• sympathetic nervous system regulates melatonin

Question 6

How does the Pineal Gland “see” Light?

Answer 6

1) light signals to suprachiasmatic nucleus
2) signal sent to spinal cord + superior cervical ganglia
3) postganglionic sympathetic fibres signals to pineal
4) dark = ↑ melatonin / light = ↓ melatonin