Endocrine System Flashcards
Main functions of the Endocrine gland
> Maintain body homeostasis
Help the body to react to stress in concert with nervous system
Regulate growth and development including sexual development and reproduction
How does the endocrine accomplish functions
by synthesis and secretion of hormones
Main type of hormones
Protein and glycoproteins > insulin
Small peptide hormones > Vasopressin
Hormones derivatives of amino acids > Adrenalin
Steroids derived from cholesterol > Testosterone
Major endocrine organs
principal or only role is to produce hormone
thyroid and adrenal gland
Organs with partial but significant edocrine role
pancreas, ovary, testes
Diffuse endocrine system
scattered cells within organs that fulfil an endocrine function
> enteroendocrine cells of gut
Major endocrine glands
Pituitary Gland Hypothalmus Pineal Gland Thyroid Gland Parathyroid gland Thymus Adrenal Gland Pancreas Gonads- Ovaries and Testes
Pituitary Gland
master gland
hormone regulate activity of many other endocrine glands
Where does the pituitary gland sit
In the sella turcica of sphenoid bone and is just below hypothalamus
How many lobes does the pituitary gland have ?
2 lobes
What are the lobes of the pituitary gland called?
Anterior lobe or adenhypophysis
Posterior lobe or neurohypophysis
Andrenohypophysis develops as…
an upward pocket of epithelium in the roof of the oral cavity called the Rathke’s Pouch
Neurohypophysis develops as…
downwards growth of the hypothalamus and stays attached to the hypothalamus by pituitary stalk
Hormones secreted into the anterior pituitary are controlled by?
hormones secreted from hypothalamus above
Factors that control the secretion of the hormones are delivered to the anterior pituitary via…
hypothalamic- hypophyseal portal system
Secretory cells of the anterior pituitary and how they stain
Acidophils - acid dyes
Basophils - basic dyes
Chromophobes - stain lightly
What are acidophils and basophils collectively known as ?
Chromophils
Somatotrophs and Lactotrophs
Acidophils
Thyrotrophs, corticotrophs and gonadotrophs
Basophils
what is used to identify each cell
immunohistochemistry
Posterior pituitary consists of …
and where do these travel
axons of nerve cells in Supraoptic and paraventricular nuclei of the hypothalamus
down the pituitary stalk and terminate near capillaries in the posterior pituitary
What are the special glial cells in the posterior pituitary called ?
Pituicytes
What are herring bodies and what do they represent?
They are swellings of axons and they represent the aggregations of oxytocin or antidiuretic hormone (vasopressin)
What is pars intermedia ?
Portion of anterior lobe bordering the posterior lobe
Pars intermedia is a lumen remnant of which pouch?
Rathke’s pouch
What does pars intermedia contain?
Follicles which contain colloid- role unknown
What is the functional unit of the thyroid glands?
Thyroid follicle, spherical space lined by epithelial cells that are low cuboidal during inactivity but are columnar when active.
Thyroid function
T3 + T4
regulate cell basal metabolism rate and hear production. Have a role in development and growth
Main thyroid hormones
Triiodothyronine > T3
Tetraiodothyronine > T4
Thyroid cells found adjacent to follicular cells ?
C cells or parafollicular cells
C cells
Clear in H and E
Easy to see in secretions stained for by their secretory product> Calcitonin
Calcitonin
Inhibits osteoclast activity and lowers blood calcium
Where are C cells derived from?
derivatives of neural crest > these cells invade thyroid during embryological development
Parathyroid Gland
4 small oval glands on posterior surface of thyroid gland
What does the parathyroid gland produce?
Parathyroid hormone
- a polypeptide hormone essential for life
Parathyroid hormone
increases serum calcium by
> stimulates release of calcium from bones
> Increases calcium reabsorption
> Increases calcium absorption from gut
3 principal cells found in the parathyroid
Principal or chief cells
Oxyphils
Adipose cells (occasionally )
Principal or chief cells
small, lightly stained with dark central nuclei
secrete PTH
Oxyphils
Large, eosinophil cells, appear at puberty and become more numerous with age
Larger number of mitochondria
Function unknown
Adrenal gland
cortex and medulla
Cortex
Formed of epithelial cells
Medulla
Formed of neural crest cells
modified sympathetic ganglion where the postganglionic neurons have lost their axons and instead release their transmitter (adrenalin and noradrenalin) into the blood
Cortex has 3 distinct layers called?
Zona Glomerulosa
Zona Fasciculata
Zona Reticularis
cortex secret three types of cholesterol based steroid hormones :
Mineralocorticoids
Glucocorticoids
Sex hormone
Mineralocorticoids
electrolyte and fluid homeostasis
- aldosterone - promotes Na + retention in distal convoluted tubules of kidney
Produced in outer layer of adrenal cortex- Zona glomerulosa
Glucocorticoids
involved in many aspects of blood
> raising blood glucose, promoting breakdown of proteins and liberation of lipids from fat stores
Produced in middle layer of adrenal cortex, Zona fasciculata - broadest band
secretion of cortisol controlled by ?
ACTH from anterior pituitary
sex hormones
Produced by inner thin layer of adrenal cortex, Zona reticularis, produce small amounts of androgens as well as glucocorticoids
Zona Glomerulosa
Mineralocorticoids (aldosterone)
Zona Fasciculata
Glucocorticoids (cortisol)
Zona Reticularis
Sex hormones ( various androgens)
what type of gland is the pancreas
endocrine and exocrine
What are the islets of tissue in the endocrine pancreas called?
Islet of Langerhans
Cells of the endocrine pancreas?
Insulin secreting cells
Glucagon secreting cells
Somatostatin secreting cells
tInsulin secreting cells
- causes lowering of blood glucose
lack of insulin causes type 1 diabetes mellitus
Glucagon secreting cells
-causes elevation of blood glucose
released into bloodstream by liver
Somatostatin secreting cells
Inhibits insulin and glucagon secretion but its role is unclear
Immunohistochemistry
An antibody specific for some markers on or in a specific cell type is used to label tissue secretions
Testes
produce spermatozoa but also secret testosterone (leydig cells)
Ovaries
produce ova > secrete female hormones - Oestrogen and progesterone
