Endocrine System Flashcards by Bethany Matthews

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

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How does the endocrine accomplish functions

by synthesis and secretion of hormones

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Main type of hormones

Protein and glycoproteins > insulin
Small peptide hormones > Vasopressin
Hormones derivatives of amino acids > Adrenalin
Steroids derived from cholesterol > Testosterone

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Major endocrine organs

principal or only role is to produce hormone

thyroid and adrenal gland

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Organs with partial but significant edocrine role

pancreas, ovary, testes

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Diffuse endocrine system

scattered cells within organs that fulfil an endocrine function
> enteroendocrine cells of gut

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Major endocrine glands

Pituitary Gland
Hypothalmus 
Pineal Gland 
Thyroid Gland 
Parathyroid gland 
Thymus 
Adrenal Gland 
Pancreas 
Gonads- Ovaries and Testes

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Pituitary Gland

master gland

hormone regulate activity of many other endocrine glands

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Where does the pituitary gland sit

In the sella turcica of sphenoid bone and is just below hypothalamus

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How many lobes does the pituitary gland have ?

2 lobes

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What are the lobes of the pituitary gland called?

Anterior lobe or adenhypophysis

Posterior lobe or neurohypophysis

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Andrenohypophysis develops as…

an upward pocket of epithelium in the roof of the oral cavity called the Rathke’s Pouch

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Neurohypophysis develops as…

downwards growth of the hypothalamus and stays attached to the hypothalamus by pituitary stalk

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Hormones secreted into the anterior pituitary are controlled by?

hormones secreted from hypothalamus above

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Factors that control the secretion of the hormones are delivered to the anterior pituitary via…

hypothalamic- hypophyseal portal system

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Secretory cells of the anterior pituitary and how they stain

Acidophils - acid dyes
Basophils - basic dyes
Chromophobes - stain lightly

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What are acidophils and basophils collectively known as ?

Chromophils

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Somatotrophs and Lactotrophs

Acidophils

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Thyrotrophs, corticotrophs and gonadotrophs

Basophils

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what is used to identify each cell

immunohistochemistry

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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

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What are the special glial cells in the posterior pituitary called ?

Pituicytes

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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)

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What is pars intermedia ?

Portion of anterior lobe bordering the posterior lobe

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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

Endocrine System Flashcards

(60 cards)