Adrenal and Pineal Microstructure Flashcards
What are the 2 parts of the adrenal gland?
cortex and medulla
What does the cortex produce?
mineralocorticoids, glucocorticoids and androgens
What does the medulla produce?
catecholamines (epinephrine and norepinephrine)
What are the layers of the adrenal gland from outside to inside?
capsule, zona glomerulosa, zona fasciculata, zona reticularis and medulla
What does zona glomerulosa produce?
steroid hormone and mineralocorticoid aldosterone
How are the cells organized in the zona glomerulosa?
into lobules of cells surrounded by the CT
What is the function of the zona glomerulosa?
secretes mineralocorticoids that regulate sodium and potassium homeostasis and water balance: main secretion aldosterone.
What does the zona facsciculata produce?
cortisol steroid hormone
How are the cells arranged in zona fasciculata?
Cells are arranged in columns with capillaries (fenestrated) lying in between the columns. Cells look frothy and pale staining.
Why do the cells of the zona glomerulosa and fasciculata have a spongy look?
because they contain many lipid droplets
What hormone controls the secretions of the adrenal cortex?
CRH (corticotropin releasing hormone) from the hypothalamus and ACTH from the anterior pituitary
What are the functions of cortisol?
- Promotes normal carbohydrate metabolism
- stimulates glycogen synthesis in the liver.
- Stimulates mobilization of fats
- Suppresses inflammation
- Involved in resistance to stress
What is produced by zona reticularis?
dehydroepiandrosterone (DHEA) steroid hormone
What regulates synthesis and secretion of DHEA?
CRH (from hypothalamus) and ACTH (from anterior pituitary)
Describe the histology of the zona reticularis
cells appear more dense in this area/stain more intensely, fewer lipid droplets than the other zones, and cells are arranged in bundles
What 2 types of cells does the medulla contain?
Chromaffin cells and autonomic ganglion cells
What are chromaffin cells?
Modified neurons (postganglionic sympathetic) of the medulla. There are 2 types, one that makes epinephrine and one that makes norepinephrine. Cells have many dense secretory granules. Don’t develop their own processes. Found near fenestrated capillaries.
What stimulates a chromaffin cell?
ACh released from the preganglionic sympathetic neuron whose cell body lies in the lateral horn of spinal cord.
What inhibits chromaffin cells from developing their own processes?
glucocorticoids (cortisol) made in the cortex.
How are glucocorticoids transported to the chromaffin cells?
via the blood supply. Takes the route from the artery to vein that has no capillary beds in the cortex.
What does the pineal gland develop from?
Neuroectoderm
What does the pineal gland regulate?
is a photosensitive organ that regulates day/night cycles and circadian rhythm.
What are the three cell/molecules of the pineal gland parenchyma?
- pinealocytes
- astorcytes (supprotive, glial-type cells)
- corpora arancea (brain sand, precipitates of Ca and K)
What are pinealocytes?
Large cells with pale nuclei and prominent nucleolus. Secretes the products of the pineal gland.
What does the pineal gland produce?
Melatonin which comes from serotonin
How does the pineal gland receive light information from the environment?
light from the retina is sent to the suprachiasmatic nucleus of the hypothalamus. Fibers then descend to the superior cervical ganglion and then post ganglionic fibers are sent back up to the pineal gland telling it to either produce more or less melatonin depending on the environment.
When are melatonin levels high?
At night. Day light inhibits production of melatonin, so serum levels during the day drop.
What is the rate limiting steop of melatonin formation?
serotonin-N-acetyltransferase
What does the pineal gland regulate?
regulates reproductive functions by inhibiting steroidogenic activity of the gonads.
Role in adjusting to changes in day length
role in emotional response to change in length of day and temperature.
