Endocrine Histology and Embryology Flashcards
What is the primary function of the endocrine system
aid in establishment and maintenance of homeostasis
What is the main difference between endocine and exocrine glands
endocrine glands release their products directly into the bloodstream (ductless Glands), Exocrine glands release their products through ducts to an external environment (duct glands)
What are endocrine cells called
??
What is the chemical signal of the endocrine system
hormones
what determines cell response with the endocrine system
??
How fast is the speed of onset of the endocrine system
??
What is the duration of action of the endocrine system
??
What are the 9 main endocrine glands of the endocrine system
Pituitary (anterior and posterior) Hypothalamus Pineal Thyroid Parathyroid Thymus Adrenal glands pancreatic islets ovaries/testes
What is a hormone
a long distance chemical mediator produced by an endocrine gland, released into the bloodstream and transported to its target cells where it interacts with specific cells and affects cell function
What are the three main types of hormones
protein/peptide hormones
steroids (cholesterol based)
Eicosanoids
Where is the hypothalamus located, what is it made of, and what does it secrete
it is located at the base of the brian
it is made of brain tissue
It secretes ADH (anti-diuretic hormone) and Oxytocin
as well as hypothalamic-releasing and inhibiting hormones
What part of the brain in development develops into the hypothalamus, pituitary, and pineal gland
the Diencephalon
What cells of the hypothalamus secrete ADH and Oxytocin, and what happens to them once they are secreted
the neurosecretory cells secrete ADH and Oxytocin, once they are secreted they go to the posterior pituitary for storage, until they are released into the bloodstream
What is another name for the hypophysis
pituitary gland
where is the pituitary gland found
at the base of the hypothalamus
what are the two parts of the pituitary gland
the anterior and posterior pituitary
what tissue is the anterior pituitary made of
glandular epithelium
what tissue is the posterior pituitary made of
neural tissue
What are the steps in development of the pituitary gland
- infundibulum extends from the diencephalon toward the stomodeum
- Rathke’s pouch evaginates up from the stomodeum up towards the infundibulum
- Rathke’s pouch loses connection with the stomodeum, and lies anteriorly to the infundibulum
- Rathke’s pouch develops into adenhypophysis
- infundibulum develops into neurohypophysis
What are the three parts of the adenohypophysis
anterior lobe (pars distalis) pars tuberalis (surrounds infundibulum) Pars intermedia (cells that form between ant. and post. pituitary)
What are the three parts of the neurohypophysis
pars nervosa (posterior lobe)
pituitary stalk
infundibuluar recess
what is found in the pars nervosa
lots of non-myelinated axons and nerve endings
what are herring bodies
where the non-myelinated axons in the pars nervosa terminate
what is found in the infundibulum
nerve tracts from the hypothalamus to the pars nervosa
Where does the hypothalamus release its hormones
into the interstitial fluid of the median eminence
what kind of capillaries are found in the median eminence of the pituitary gland
fenestrated
what is the blood vessel system like in the pituitary gland
it is a portal system
there is a superior hypophyseal artery which enters the pituitary at the median eminence, where it picks up the hypothalamic hormones and takes them to the anterior pituitary through portal vessels.
there is an inferior hypophyseal artery which enters the posteior pituitary, picks up those hormones.
all the vessels leave as hypophyseal veins
which neurons of the hypothalamus send their hormones to the anterior pituitary, via the superior hypophyseal artery, after releasing them to the median eminence
neurosecretory neurons
which neurons of the hypothalamus send their hormones to the posterior pituitary
the supraoptic nuclei, and the paraventricular nuclei
What are the three ways in which the hypothalamus regulates the body
direct control by nervous system
direct release of hormones
indirect release of hormones
what body tissues does the hypothalamus directly control by the nervous system
the adrenal medulla, which secretes epinephrine and norepinephrine
what body tissues does the hypothalamus directly control by hormones
the posterior pituitary, which secretes ADH (kidneys) and Oxytocin (prostate and uterine smooth muscle and mammary glands)
what body tissues does the hypothalamus indirectly control through hormones
the anterior pituitary, the hypothalamus tells it to secrete its hormones
what are the 7 hormones of the anterior pituitary
ACTH (adrenal corticotropic hormone) TSH (thyroid stimulating hormone) GH (growth hormone) PRL (prolactin) FSH (follicle stimulating hormone) LH (leutinizing hormone) MSH (melanocyte stimulating hormone)
what is the action of ACTH
it causes the adrenal cortex to secrete glucocorticoids
what is the action of TSH
it causes the thyroid to secrete thyroid hormones
what is the action of GH
it causes the liver to secrete somatomedins, which affect bone, muscle and other tissues
what is the action of PRL
it causes milk production from the mammary glands
what is the action of FSH and LH
they cause the testes to produce inhibin and testosterone
they cause the ovaries to produce estrogen, progesterone, and inhibin
what is the action of MSH
it goes to the melanocytes, action is uncertain
what are the three disorders of GH
hyposecretion = pituitary dwarfism
hypersecretion before growth plates fuse = gigantism
hypersecretion after growth plates fuse = acromegaly
What are the pharyngeal arches, pouches, and grooves derived from
arches = mesoderm pouches = endoderm grooves = ectoderm
how many pairs of pharyngeal pouch pairs are there
4 (the 5th goes away)
What develops from the 1st pharyngeal pouch
the tympanic cavity and pharyngotympanic tube
what develops from the 2nd pharyngeal pouch
the palatine tonsil
what develops from the 3rd pharyngeal pouch
the inferior parathyroid and they thymus
what develops from the 4th pharyngeal pouch
the superior parathyroid and the ultimopharyngeal body
what is the fate of the ultimopharyngeal body, and what does it secrete
it becomes the parafollicular cells (C-cells), and they secrete calcitonin
what is the function of calcitonin
decreases blood calcium (opposition to the parathyroid hormone)
What are the steps in the development of the thyroid gland
- thyroid primordium forms at the foramen cecum
- thyroid primordium moves down the thyroglossal duct
- thyroglossal duct dissapears
- two thyroid lobes connect via an isthmus
- thyroid descends to inferior of the cricoid cartilage
what forms if the thyroglossal duct persists
a thyroglossal cyst or sinus
What stimulates the thyroid to secrete its hormones, what are its hormones
thyroid stimulating hormone stimulates the thyroid to secrete Calcitonin, Triiodothyronine(T3), and thyroxin (T4)
What are the teo types of cells in the thyroid
follicular cells
parafollicular cells
what are the follicular cells and parafollicular cells like histologically
follicular cells are simple cuboidal epithelium
parafollicular cells are cuboidal
What are the functions of T3 and T4
increase metabolism and assist in growth and development
what is required for synthesis of T3 and T4
iodine
what causes a goiter
too little iodine
what are the symptoms of hypothyroidism (Myxedemia)
fatigue weakness weight gain hair loss depression decreased libido
what are the symptoms of hyperthyroidism (graves disease)
palpitations nervousness heat intolerance insomnia fatigue fast heart rate weight loss bulging eyes
what causes the secretion of cacitonin
high blood calcium levels
what is caused when the thyroid fails to develop properly
cretinism
what is the parathyroid gland
4 bean shaped glands embedded in the fascial sheath of the thyroid that secrete parathyroid hormone
what is the function of parathyroid hormone
causes calcium to be moved into the blood from the bones (brakes down bones)
What are the two divisions of the adrenal gland
the adrenal cortex (outside) and the adrenal medulla (inside)
what are the three layers of the adrenal cortex from superficial to deep
glomerulosa
fasciculata
reticularis
what does the adrenal medulla secrete
catecholectamines (epinephrine and norepineprhine)
Where do the medulla and cortex originate from
medulla originates from the ectoderm
cortex originates from the mesoderm
what are the steps in the development of the adrenal glands
- mesothelial cells penetrate underlying mesencyhme
- these cells differentiate into cortex
- mesothelial cells penetrate mesenchyme again
- these 2nd cells surround the first cells, and most of the first cells regress, except the reticularis zone
- neural crest cells invade the medial aspect of the cortex
- these neural crest cells invade and arrange in clumps and cords = adrenal medulla
what are chromaffin cells
the neural crest cells that invade the primitive cortex and form the adrenal medulla
what are the types of hormones (and specific hormones) secreted from the three layers of the adrenal cortex
Glomerulosa = mineralocorticoids (aldosterone) Fasciculata = glucocorticoids (cortisol) reticularis = sex hormones
what is the function of aldosterone, and what causes it to be secreted
it causes sodium reabsorption into the blood in the kidneys, which causes water retention and assists in maintaining blood pressure.
blood pressure and electolyte balance regulate it by angiotensin 2
what is the function of cortisol and what causes it to be secreted
it causes increase blood glucose, and decreases antibodies
it is regulated by ACTH (but caused by stress)
what is the function of the sex hormones from the adrenal cortex and what regulates their secretion
they supplement the sex hormones from the gonads, and they are regulated by ACTH
What is the disease with excessive ACTH
cushing syndrome
- hyperglycemia and glucosuria
- fat in the face, mid section, and above the shoulders
- muscle tissue breakdown
what is the disease with insufficient ACTH
addison disease
- weight loss
- fatigue
- hypotension
- skin darkening
What are the two hormones secreted from the chromaffin cells of the adrenal medulla, what is their function, and what regulates them
epinephrine, norepinephrine (small amounts of dopamine)
they are important in fight or flight
they are regulated by the nervous system
What is the pancreas
an organ with endocrine and exocrine function that lies below the stomach, and is attached to the duodenum, and is 90% acinar (exocrine) cells
What are the steps in the development of the pancreas
- dorsal and ventral pancreatic buds grow off of the duodenum
- the ventral bud moves around the duodenum and joins with the dorsal bud
- the dorsal bud makes the head, body, and tail. the ventral bud makes the ucinate process and the main pancreatic duct
What occurs when the ventral buds of the pancreas migrate in opposite directions around the duodenum
you have an annular pancreas, with which the duodenum will be constricted by the pancreas that has formed around it
most of the pancrease if composed of ductal and exocrine glands, what is the remaining part of the pancreas made of
islets
what are pancreatic islets? and why do they get most of the blood supply to the pancreas
the islets are where alpha, beta and delta cells are located. They get most of the blood supply to the pancreas because they are the endocrine portion of the pancreas (thus they secrete hormones into the blood)
What do alpha, beta, and delta pancreatic cells produce
alpha cells produce glucagon
beta cells produce insulin
delta cells produce somatostatin
