endocrine Flashcards
Are gonads considered endocrine glands or endocrine tissues?
endocrine glands
Define hormones.
Hormones are chemical regulators of various body functions such as growth and reproduction
How are hormones transported?
They’re secreted into the blood and transported by the blood to affect the functions of their target cells.
What is the general scheme of hormone function?
stimulus–> gland with hormone in it–> hormone secretion–> to the blood–> blood transports hormone to the target cell–> action
Compounds acting as hormones are classified according to their chemical structure. What are the three divisions?
Steroids, amines, proteins & polypeptides
What are hormones made of 100 or more amino acids called?
proteins (less than 100 is a polypeptide)
Where do steroid hormones bind?
to cytoplasmic receptors and increase protein synthesis by mitochondria and ribosomes
Where do thyroid hormones bind?
to nuclear receptors and increase gene transcription in the cell nucleus
Where do hormones other than steroid or thyroid hormones bind?
to cell membrane receptors and activate cAMP, DAG, or inositol triphosphate second messanger systems
When blood level of the endocrine gland hormone reach an optimum value, it inhibits secretion of the hypothalamic and anterior pituitary hormones that stimulate the gland. What is the control of secretion called?
Negative feedback secretion
When the response to an endocrine gland hormone reach an optimum level, it increases secretion of the hormone that stimulate the response. What is the control of secretion called?
Positive feedback
Where is the hypothalamus?
central area of the basal brain limbic system (back of the head, towards the bottom)
What are the hypothalamic hormones?
they makes the endocrine system work
What are the 9 hypothalamic hormones?
GHRH, GHIH (somatostatin), PRH, PIH (dopamine), CRH, GnRH, TRH, ADH, OT
Where are OT and ADH secreted from?
Posterior pituitary
What ar ethe two parts of the pituitary gland?
anterior (adenohypophysis) and posterior (neurohypophysis)
What is the posterior pituitary?
derived form neural brain tissue and connects to the hypothalamus by the hypothalamic hypophyseal tract (secreteds ADH and OT)
What is the anterior pituitary?
derived from ectodermal tissue in the roof of the embryonic mouth and connects to the hypothalamus by the hypophyseal portal blood vessels
Both nuclei of the hypothalamus, paraventricular and supraoptic nucleus, produce both OT and ADH but whihc produces which dominantly?
paraventricular- OT
supraoptic- ADH
A polypeptide hormones of 9 amino acids. Target tissue are kidneys, sweat glands and the blood arterioles, what hormone am I?
ADH (vasopressin)
- causes kidneys and sweat glands to conserve water to increase blood volume
- causes vasoconstriction of arterioles to increase blood pressure
A polypeptide hormone of 9 amino aicds. Target tissues are the smooth muscles of reproductive system of both sexes. What hormone am I?
OT
male- contraction of smooth muscles during ejaculation
female- labor contractions and release of milk from mammary glands
Somatotropes
human growth hormone (hGH)
Corticotropes
Adrenocortecotropin (ACTH)
Thyrotropes
Thyroid Stimulating Hormone (TSH)
Lactotropes
Prolactin (PRL)
Gonadotropes
Gonadotropic Hormones (follicle stimulating hormone (FSH) and luteinizing hormone (LH))
What is pituitary dwarfism caused by?
GH hyposecretion in children and adolescents resulting in a small body
What is acromegaly?
GH hypersecretion in adults– causes soft bones to grown
What tissue does th TSH target?
thyroid gland- stimulates secretion of thyroid hormones
What tissue does ACTH target?
adrenal cortex, stimulates secretion of the adrenal cortex hormones
What tissue does prolactin target (PRL)?
mammary glands- only one that doesn’t target a hormonal tissue- stimulates milk production in the mammary glands in concert with other hormones
Gonadotropins are what and target what tissues?
FSH and LH
target the ovaries and the testes
control female and male reproductive physiology
All the hypothalamic and pituitary hormones are controlled by ____ _____ from peripheral endocrine glands hormones.
negative feedback
Where is the thymus gland located?
superior to the heart
What does they thymus gland secrete?
thymopoietin and thymosin hormones that regulate the developement anf activation of the T-lymphocytes
Where is the pineal gland?
found in the roof of the third ventricle of the brain (above the hypothalamus and pituitary gland)
The pineal gland secretes what?
serotonin by day and melatonin at night
What are the eight steps of thyroid hormone synthesis?
Iodide trapping Synthesis of thyroglobulin oxidation of iodide organification of tyrosine coupling of T1 & T2 Pinocytosis Secretion of T3 & T4 Transport of T3 & T4
Where is the thyroid gland located?
in the neck below the voice box (larynx)
What is the difference between RT3 (3,3’,5’) and T3 (3,5,3’)?
reverse T3 is not active and will be rebroken and reused