Endocrine System Flashcards
Functions of endocrine system
Maintain body homeostasis, help the body react to stress and regulate growth and development, including sexual development
How does the endocrine system achive its functions
Through the production and secretion of hormones
What are the main types of hormones produced by the endocrine system
Protein and glycoprotein, small peptide, derivatives of amino acids and steroids derived from cholesterol
What does the endocrine system consist of
Major endocrine organs, organs with partial endocrine roles and the diffuse endocrine system
What is the origin of most endocrine tissue
Epithelial
Some major endocrine glands
Pituitary, hypothalamus, pineal, thyroid, parathyroid, thymus, adrenal glands, pancreas and gonads
Why is the pituitary known as the master gland
As its hormones regulate the activity of many other endorine glands
Where is the pituitary located
Sella turcica of the sphenoid bone
Another name for the pituitary
Hypophysis
What are the two lobes of the pituitary
Anterior/adenohypothysis and posterior/neurohypophysis
What is the posterior lobe developed from
Downwards growth of the hypothalamus
What attaches the posterior lobe to the hypothalamus
Pituitary stalk
What does the anterior lobe form from
An upwards pocket of epithelium in the roof of the oral cavity called Rathke’s pouch
What controls the secretion from the anterior pituitary
Hormones released from the hypothalamus
How are the hormones from the hypothalamus delivered to the anterior pituitary
In high concentrations through they hypothalamic-hypophyseal portal system
What hormones does the pituitary secrete
Oxytocin, ADH, growth hormones, prolactin, gonadotropins, ACTH and TSH
What are the hypothamic hormones that regulate the anterior pituitary
Growth-releasing hormone, somatostatin, thyrotropic-releasing hormone, corticotrophin-hormone, alopanine and gonadotropin-releasing hormone
What does the anterior pituitary consist of
Packed secretory cells interspersed with fenestrated endothelium-lined vascular sinuses
What are the cells of the anterior pituitary
Acidophils, basophils and chemophobes
What are acidophils and basophils known as collectively
Chromophils
What does the posterior pituitary consist of
Axons of nerve cells in the suraoptic and paraventricular nuclei of the hypothalamus
What are the special glial cells within the posterior pituitary
Pituicytes
What are the swellings in the axons of the posterior pituitary
Herring bodies
What are herring bodies
Aggregations of oxytocin or ADH
What is the portion of the pituitary between the anterior and posterior lobes
Pars intermedia
What is the pars intermedia
The remnants of the lumen of Rathke pouch
What is contained within the pars intermedia
Follicles that contain a colloid
What is the functional unit of the thyroid gland
Thyroid follicle
What is the thyroid follicle
A spherical space lined by epithelial cells that are low cuboidal when inactive
What regulates the basal cell metabolism and heat production
T3 and T4
What are C cells
Cells adjacent to the follicle cells
They are within the basal lamina that surrounds the follicle
What do C cells produce
Calcitonin
What function does calcitonin have
Inhibits osteoclast activity and lowers blood calcium
What are C cells derived from
Neural crests
What are the parathyroid glands
Four oval glands on the posterior surface of the thyroid gland
What do the parathyroid glands produce
Parathyroid hormone
Function of parathyroid hormone
Increases serum calcium by stimulating the release of calcium from bone, increasing renal calcium absorption and increasing calcium absorption from the gut
What are the 3 cells within the parathyroid glands
Principle/chief cells, oxyphils and occasional adipose cells
Chief cells
Small, lightly stained cells with dark, central nuclei
Secrete PTH
Oxyphils
Larger eosinophil cells
Appear at puberty and become more numerous with age
Have large numbers of mitochondira
What surrounds the parathyroid gland
Connective tissue capsule
What forms the adrenal cortex
Epithelial cells
What forms the adrenal medulla
Neural crest cells
What surrounds the adrenal glands
A thick capsule with connective tissue trabeculae extending inwards through the cortex
Layers of the adrenal cortex
Zona glomerulosa
Zona fasciculata
Zona reticularis
What type of hormones are secreted by the zona granulosa
Mineralocorticoids
Function of mineralocorticoids
Electrolyte and fluid homeostasis
What is the main mineralocorticoid
Aldosterone
Function of aldosterone
Promotes Na+ retention in the distal convoluted tubule of the kidney
What type of hormones does the zona fasciculata produce
Glucocorticoids
Unction of glucocorticoids
Involved in many aspects of metabolism
What is the main glucocorticoid produced
Cortisol
Control of secretion of cortisol
ATCH from the anterior pituitary
What type of hormones does the zona reticularis produce
Sex hormones
What does the adrenal medulla reinforce
The actions of the sympathetic nervous system at times of stress
Cells of the adrenal medulla
Slightly basophilic and arranged in cords and nests
Consist of granules of adrenaline and noradrenaline
What type of gland is the pancreas
Both exocrine and endocrine
What does the endocrine pancreas consist of
Scattered islands of tissue called islets of Langerhan
Blood supply of the islets of Langerhan
Have a rich blood supply
Secretory cells of the pancreas
Lightly stained and spherical-clustered cells
Principle cells within the pancreatic islets
Insulin secreting cells, glucagon secreting cells and somatoststin secreting cells
Function of insulin secreting cells
Lowering of blood glucose
Function of glucagon secreting cells
Elevation of blood glucose
Function of somatostatin secreting cells
Inhibit insulin and glucagon secretion
What is an antibody
A identifiable marker on or in a specific cell
What hormone do the testes produce and what cell produces it
Testosterone and the Leydig cells
What hormones do the ovaries produce
Oestrogen and progesterone
