Endocrine System Histology Flashcards
Where do exocrine glands secrete hormones?
Onto a surface, either directly or through a duct
Where do endocrine glands secrete their hormones?
Internally, ductless glands; utilize the cardiovascular system primarily for distribution
What are the two types of hormones?
Circulating and local
What are the two kinds of local hormones?
Paracrine and autocrine
What do paracrine excreted hormones end up interacting with?
nearby target cells
What do autocrine excreted hormones end up interacting with?
The same cell that secreted the hormone
What is the main role of the hypothalamus?
Main visceral control center for the body; the autonomic control center
What does the hypothalamus regulate? (6)
Body temperature, food intake, water balance/thirst, sleep-wake cycles, sexual behavior, and endocrine system functioning
The hypothalamus’s influence is vital to the body maintaining what?
Homeostasis
The hypothalamus is a major link between what two body systems?
The nervous system and the endocrine system
the hypothalamus is also called the command center for what?
The endocrine system
The hypothalamus secrets how many hormones?
9 hormones
The hypothalamus is connected to the pituitary gland via what?
The infundibulum
The pituitary gland is as the _______ gland of the endocrine system.
Master gland
The pituitary and the hypothalamus together regulate what?
Virtually all aspects of growth, development, metabolism, and homeostasis
The pituitary gland is also known as what?
Hypophysis
The pituitary gland sits in what?
The hypophyseal fossa within the sella turcica of sphenoid bone
What are the two significant parts of the pituitary gland?
The anterior lobe, (anterior pituitary, adenohypophysis) and the posterior pituitary (posterior lobe, neurohypophysis)
What are the three parts of the anterior pituitary?
Pars distalis, pars intermedia, pars tuberalis
Describe the pars distalis.
Bulk of anterior lobe of pituitary gland, cords of epithelial cells interspersed with fenestrated capillaries; develops from anterior wall of Rathke’s pouch
Describe the pars intermedia.
Thin remnant of posterior wall of Rathke’s pouch; next to pars distalis; the pars intermedia surrounds a series of colloid-filled follicles that represent the residual lumen of Rathke’s pouch
Describe the pars tuberalis.
From thickened lateral walls of Rathke’s pouch; forms a collar or sheath around infundibulum
Most cells around the pars tuberalis are what?
Basophilic gonadotropic cells
What are the two parts of the posterior pituitary?
Pars nervosa and infundibulum
Describe the pars nervosa.
Neurosecratory axons and their endings
Describe the infundibulum.
Contains neurosecratory axons forming the hypothalamo-hypophyseal tracts
The pituitary gland is derived in part from what two things?
An outpocketing of the ectoderm lining the roof the the mouth called the hypophyseal (Rathke’s) pouch and in part from an outpocketing of the neuroectoderm lining the floor of the hypothalamus called the neurohypophyseal bud
The anterior lobe develops from what?
The roof of the mouth (Rathke’s pouch)
The anterior pituitary is stimulated by what? (generally)
Releasing hormones (five of these)
The anterior pituitary is inhibited by what? (generally)
Inhibiting hormones (2) and negative feed back
How do the regulating hormones from the hypothalamus reach the anterior lobe of the pituitary?
The hypothalamo-hypophyseal portal system
What is the primary plexus of the hypothyseal portal system?
This is where the hypothalamic hormones secreted from the axon terminals will diffuse into the hypothyseal portal system
The hormones that enter the primary plexus of the hypophyseal portal system will eventually end up where?
In the cells of the pars distalis
There are what two cells in the pars distalis based on staining affinity and what volume do they contribute?
Chromophils and chromophobes (each contribute 50% total volume)
What are the two types of chromophils and what percent do they contribute to the total percent in the pars distalis?
Basophils (10%) and acidophils (40%)
What are the three kinds of chromophils that are basophils?
Gonadotropes, corticotrops, and thyrotropes
What percent does gonadotrophes contribute to the anterior lobe?
10%
What percent does corticotropes contribute to the anterior lobe?
15-20%
What percent does thyrotropes contribute to the anterior lobe?
5% least abundant
What are the two types of chromophils that are acidophils?
Somatotropes and lactotropes
What percent of the anterior lobe do the somatotropes make up?
50% most abundant
What percent of the anterior lobe do the lactotropes make up?
15-20%
What cell, cell type, and staining affinity secretes hGH?
Somatotrope; chromophil; acidophil
What cell, cell type, and staining affinity secretes TSH?
Tyrotropes; chromophil; basophil
What cell, cell type, and staining affinity secretes FSH?
Gonadotropes; chromophil; basophil
What cell, cell type, and staining affinity secretes LH?
Gonadotropes; chromophil; basophil
What cell, cell type, and staining affinity secretes PRL?
Lactotropes; chromophil; acidophil
What cell, cell type, and staining affinity secretes ACTH?
Corticotropes; chromophil; basophil
What cell, cell type, and staining affinity secretes MSH?
Corticotropes; chromophil; basophil
What are the two hormones stored in the posterior pituitary gland?
Oxytocin (OT) and ADH
The posterior pituitary contains what? (4)
Axons and axon terminals of hypothalimic nerosecretory neurons, along with fibroblasts, mast cells, and pituicytes
What are pituicytes?
A type of glial cell, resembling the astrocyte, that associates with the fenestrated capillaries; cell has many branches; pigment vesicles in cytoplasm; nuclei is round or oval, and this is the most common cell type in the posterior pituitary
Where are the two hormones found in the posterior pituitary synthesized?
Within the cell bodies of the neurosecratory neurons in the hypothalamus
What form the hypothalamo-hypophyseal tract in the infundibulum?
The axons of the hypothalamic neurosecratory neurons
What are herring bodies?
This is where hormones in the posterior pituitary are stored
What does the pineal gland regulate?
Daily body rhythm; day/night cycle (circadian rhythm)
What is the major hormone produced in the pineal gland?
Melatonin
What are the two cell types in the pineal gland?
Pinealocytes (parenchymal cells) 95% and interstitial (glial) cells 5%
What is the very characteristic histologic structure that can be found in the pineal gland?
Brain sand (corpora arenacea)
What are the two parts of the adrenal gland?
Cortex and medulla
The cortex is what percent of the adrenal gland?
80-90%
What are the layers of the adrenal gland starting from superficial to deep?
Zona glomerulosa, zona fasciculata, zona reticularis and adrenal medulla
The zona glomerulosa secretes what type of hormone, what main hormone and what is the main function of that hormone?
Mineralcorticoid hormone, aldosterone, this regulates Na+, K+, and water; control of blood pressure
The zona fasciculata secretes what type of hormone, what main hormone and what is the main function of that hormone?
Glucocorticoid hormone, cortisol, ragulates glucose and fatty acid metabolism, suppresses the immune system; provides resistance to stress
The zona retucularis secretes what type of hormone, what main hormone and what is the main function of that hormone?
Androgen hormones, DHEA (dehydroepiandrosterone); assists in early growth of axillary and pubic hair in both sexes
The medulla secretes what type of hormone, what main hormone and what is the main function of that hormone?
Catecholamines; epinephrine and norepinephrine; intensify sympathetic responses in other parts of the body
The adrenal medulla is a modified what?
Sympathetic ganglion of the autonomic nervous system (ANS)
The adrenal medulla develops from what?
Neural crest cells, which are the same embryonic tissues as all the other sympathetic ganglia in the body
The modified neurons of the adrenal medulla are called what?
Chromaffin cells
The chromaffin cells are controlled by what?
Sympathetic preganglionic neurons, which allow for quick signalling to release hormones via exocytosis
What is the endocrine portion of the pancreas?
Islets of langerhans (pancreatic islets)
What are the three principle cells of the islets of langerhans?
Beta or B cells 70%, alpha or A cells 17%, and delta or D cells 7%
Beta cells of the pancreas synthesize and secrete what?
Insulin
Alpha cells of the pancreas synthesize and secrete what?
Glucagon
Delta cells of the pancreas synthesize and secrete what?
Somatostatin (identical to growth hormone-inhibiting hormone (GHIH) from hypothalamus)
Insulin stimulates what?
Glycogenesis, lowers blood glucose
Glucagon stimulates what?
Glycogenolysis, raises blood glucose
Somastostatin inhibits what secretion from the pancreas?
Insulin and glucagon
The thyroid gland secretes what two hormones?
Thyroxine (4 atoms of iodine) and Tri-iodothyronine (3 atoms of iodine)
Both thyroid hormones are important for what?
Growth, cell differentiation, control of basal metabolic rate and oxygen consumption of body cells
Parafollicular cells are found in the thyroid gland and are responsible for the production of what?
Calcitonin
What does calcitonin do?
Decrease level of calcium in the blood by encouraging calcium salts to be deposited in bone matrix and inhibit osteoclasts
What is the secretion regulation of calcitonin?
Negative feedback system, high blood Ca^2+ levels stimulate secretion and low blood Ca^2+ levels inhibit secretion
What are the two types of cells in the parathyroid gland?
Chief cells and oxyphil cells
What hormone does the parathyroid gland secrete and what cell does it come from?
Produces PTH secreted from chief cells
What does PTH do?
Increases blood calcium levels by stimulating osteoclasts to resorb bone, and additionally acts on the kidneys to slow the rate of calcium loss from the blood into the urine
How is PTH regulated?
negative feedback system, low blood Ca levels stimulate and high blood Ca levels inhibit
What are the calcium homeostasis levels in blood?
9-11mg/100ml
What is a normal blood glucose level?
90mg/100ml
