L24. Endocrine System 2 Flashcards
What happens to the pituitary gland at 4 weeks after fertilization
the oral ectoderm starts to collapse
the neural ectoderm invaginates and descends towards the oral ectoderm
What happens to the pituitary gland at 5 weeks after fertilization
The neural ectoderm that starts to descend forms the neurohypophyseal pouch
The oral ectoderm forms the Rathke’s pouch
Identify the Neurohypophyseal bud, oral ectoderm and Rathe’s pouch on pg 6 of L 24
pg 6 lecture 24
Describe what happens to the pituitary gland at 8 weeks after fertilization
The neurohypophyseal bud from the neural ectoderm forms the pituitary stalk
the oral ectoderm forms the Rathke’s pouch which then ‘breaks off’ from the oral ectoderm, the remnants form a regressing hypophyseal stalk
Where does the anterior pituitary derive from?
It is derived from the oral ectoderm
Where does the posterior pituitary derive from ?
Posterior Pituitary is derived from the neural ectoderm
What is the sella turcica
orchestration of different materials ( nervous tissue, blood supply, bone, non-nervous tissue)
Sella turcica is the bone that supports the pituitary gland
What is the pituitary stalk interruption syndrome?
truncated or absent pituitary stalk ( derived from the oral ectoderm) which implies that hormone concentration associated with the anterior pituitary decreases.
- growth failure and pituitary hormone deficiencies
What is the pars distalis ? Where does it develop from? What does it contain
anterior lobe of the pituitary
derived from the oral ectoderm
contains non-nervous tissue
What is the pas nervosa? Where does it develop from? What does it contain
posterior lobe of the pituitary
derived from the neural ectoderm
contains nervous tissue
How can HE be used to categorize cells
Can differentiate between hormone secreting and non-hormone secreting cells
marks cells that have secretory granules
Why do endocrine cells have secretory granules?
needed for hormone storage and release
Draw the anterior pituitary components ( pg 10 L 24)
pg 10 b L 24
What predominates in the anterior pituitary
cell bodies
What are chromophobic cells and what are their characteristics?
stain lightly in HE
no secretory granules
could be immature secretory cells
have a supportive function
What are chromophlic cells, what are their characteristics
stain intensely in HE
contains secretory granules
acidophilic ( means they attract acidic dyes stain red but are basic themselves)
basophilic ( means they attract basic dyes will appear blue and are acidic themselves)
What are gonadotropes
One of the unique cell type in the anterior pituitary gland
- ruled by GnRH
- makes FSH and LH
- chromophilic
- contains secretory granules
What are folliculostellate?
- support cells of gonadotropes
- have a paracrine function
- no secretory granules ( stains lightly: chromophobic)
What are the limitations in HE staining?
cannot reflect cell phenotype or cell identity
What is the product of somatotropes , acidophilic or basophilic
GH , acidophilic
What is the product of lactotrope, acidophilic or basophilic
prolactin , acidophilic
What is the product of thyrotropes, acidophilic or basophilic
TSH , basophilic
What is the product of corticotropes, acidophilic or basophilic
ACTH, basophilic
What is the product of gonadortropes, acidophilic or basophilic
FSH, TH , basophilic
Draw the posterior pituitary components ( pg 14b L 24)
pg 14b L 24
Describe the components in the posterior pituitary
- nerve terminals
- swellings and Herring bodies ( contains hormones) , packed with secretory granules
- pituicytes
- provides physical and nutritive support
- cell body and nucleus present
- neuroglial in nature
Describe the components in the anterior pituitary
- predominently filled with cell bodies
- has chromophils
- has chromophobs
Which of anterior / posterior sections would look like there are more cells
anterior portion
What is the function of the intermediate lobe of the pituitary
-secretes melanocyte-stimulating hormones which changes the skin colour
What are the 2 hormones released by the thyroid gland
- thyroid hormone
- calcitonin
What is the pathway for thyroid hormone production
- hypothalamus cells secrete the 1 hormone ( Thyroid releasing hormone in the paraventricular neuron)
- the neuron travels down the hypophyseal artery and the TSH (thyroid stimulating hormone ) is secreted in teh anterior pituitary gland which enters the hypophyseal vein
- the follicular cells in the thyroid upon receiving 2 hormone (TSH) releases the thyroid horone
What is the pathway for calcitonin hormone secretion
- elevated Ca2+ level in blood
- stimulates parafollicular cells to secrete calcitonin
Describe the relation between the follicular cell and paracfollicular cell
- act as separate units*
- follicular unit: contains follicular cell and synthesizes TH , responds to TSH from anterior pituitary
- parafollicular unit: contains chromophilic, synthesizes calcitonin, responds to changes in blood calcium
Describe calcitonin
- made by parafollicular cells
- 32 amino acid , linear polypeptide
- release is stimulated by increase in circulating Ca2+ levels
- inhibits Ca2+ action ( osteoclasts inhibited?)
What are the 2 cell types in the parathyroid gland
- chief cells
2. oxyphil cells
Describe the chief cells in the parathyroid gland
- dense cytoplasm
- has secretory granules, chromophilic
- secretes parathyroid hormones
Describe the oxyphil cells in the parathyroid gland
- could be inactive chief cells
- clear cytoplasm
- chromophobic
Describe the parathyroid hormones
- 84 amino acid polypeptide
- secretion is stimulated by decreases in the blood calcium levels
- enhances Ca2+ release in the bone, absorption in intestines and reabsorption in the kidneys
Describe the parathyroid gland
- 4 glands within the posterior part of the thyroid
- regulation is independent of the thyroid
- chief cells regulate PTH secretion
Describe the role of parathyroid and calcitonin in calcium homeostasis
- PTH increases the calcium levels
- calcitonin decreases the level of calcium
