ENDOCRINOLOGY Flashcards
Network of ductless glands that secrete hormones directly into the blood
Considered to be the regulatory system of the body
Regulated by means of control of hormone synthesis rather than by degradation
Endocrine System
Chemical signals produced by specilized cells, secreted into the blood stream and carried to a target tissues
Hormones
An increased in the product results to elevation of the activity of the system and the production rate
Ex: Gonadal, Thyroidal and Adrenocortical hormone
Positive Feedback System
An increased in the product results to decreased activity of the system and the production rate
Ex: Leutenizing Hormone
Negative Feedback system
Secreted in one location and release into blood circulation; binds to specific receptor to elicit physiological response
Endocrine
Secreted in endocrine cells and released into interstitial space; binds to specific receptor in adjacent cell and affects its dunction
Paracrine
Secreted in endocrine cells and released into interstitial space; binds to specific receptor in adjacent cell and affects its function
Paracrine Hormones
Secreted in edocrine cells and sometimes released into interstitial space; binds to specific receptor on cell of origin resulting to self-regulation of its function
Autocrine
Secreted in endocrine cells and remains in relation to plasma membrane; acts on immediately adjacent cell by direct cell-to-cell contact
Juxtacrine Hormone
Secreted in endocrine cells and remained as well as function inside the synthesis of origin
Intracrine hormone
Secreted in endocrine cells and released into lumen of gut; affects their function
Exocrine Hormone
Secreted in neurons and released into extracellular space; binds to receptor in nearby cell and affects its funciton
Neurocrine Hormone
Synthesized and stored within the cell in the form of secretory granules and are cleaved as needed
Cannot cross the cell membrane due to their large molecular size and thus; produce their effects on the outer surface of the cell
Peptides and Proteins
Follicle-Stimulating Hormone
HCG
Thyroid Stimulating Hormone
Erythropoietin
Glycoprotein
ACTH
ADH
GH
Angiotensin
Calcitonin
Cholecystokinin
Gastrin
Glucagon
Insulin
Melanocyte-Stimulating Hormone
Oxytocin
PTH
Prolactin
Somatostatin
Polypeptide
Lipid molecules that have cholesterol as a common precurosi
Produced by adrenal glands, ovaries, testes and placenta
Water insoluble (hydrophobic) and circulate bound to a carrier protein
Steroids
Derived from an amino acid & they are intermediary between steroid and protein hormones
Ex: Epinephrine, Norepinephrine, Triiodothyronine, Thyroxine
Amines
Portion of the brain located in the walls and floor of the third ventricle
Link between the nervous system and the endocrine system
Hypothalamus
Hormone
TRH
Gn-RH
GH-IH
GH-RH
PIF
Hormones produced in the Hypothalamus
Attached to the midbrain
Secretes melatonin that decreases the pigmentation of the skin
Secretions are controlled by nerve stimuli
Pineal Gland
“Master Gland”
Located in a small cavity in the sphenoid bone of the skull called the sella turcica or Turkish saddle
Connected by the infundibular stalk to the median eminence of the hypothalamus
All pituitary hormones have circadian rhythms
Pituitary Gland
Hypophysis
“True Endocrine Gland”
Regulates the released and production of hormones
Hormones are either peptides or glycoproteins
Adenohypophysis
Anterior Pituitary Gland
Secrete growth hormone
Immunochemical Test
Somatotrophs
Secrete prolactin
Immunochemical Test
Lactotrophs
Mammotrophs
Secrete TSH
Immunochemical Test
Thyrotrophs
Secrete Proopiomelandcortin produce ACTH, B-endorphin, & B-lipotropin
Immunochemical Test
Corticotrophs
Secrete LH & FSH
Immunochemical Test
Gonadotrophs
Most abundant of all pituitary hormones
Major stimulus: Deep sleep
Secretion is erratic and occurts in short burst
Growth Hormone (GH) Somatotropin
Reference Value:
(< 7 ng/mL)
Most common cause of GH deficiency in children
Children with pituitary dwarfism, normal proportions are retained and show no intellectual abnormalities
Idiopathic Growth Hormone Deficiency
Most common etiology in adult-onset GH deficiency
Pituitary Adenoma
Due to Overproduction of GH
Acromegaly
Patient preparation for Growth Hormone measurement
Rest 30 minutes before blood collection
Screening Test for measurement of GH
Result: Elevated Serum GH
Physical Activity Test
Exercise test
Confirmatory test:
GOLD STANDARD for measurement of GH
Insulin Tolerance Test
2nd Confirmatory Test for GH
It is a 24-hour or nighttime monitoring of GH
Confirmed GH deficiency: Failure of GH to rise >5ng/mL in adults & >10ng/mL in children
Arginine Stimulation Test
Screening test for detection of Acromegaly
Insulin-like Growth Factor 1 (IGF-1)
Confirmatory test for the detection of Acromegaly
Blood is collected every after 30 minutes for 2 hours
Fasting sample is required
Glucose Suppression Test
Important markers in diagnosing fertility and menstrual cycle disorders
Present in the blood of both male and female at all ages
Gonadotropins
FSH & LH
Aids in spermatogenesis in male (Sertoli cells)
Aids in follicular growth in female
Follicle-Stimulating Hormone
Helps Leydig cells to produce testosterone and is necessary for ovulation and final follicular growth in female
Luteinizing Hormone
Acts on Thecal cells to cause the synthesis of androgens, estrogens and progesterone
Luteinizing Hormone
Elevation of FSH is a clue in the diagnosis of
Premature menopause
Also known as Thyrotropin
Main stimulus for the uptake of iodide by the thyroid gland
Acts to increase the number & size of follicular cells; stimulates thyroid hormone synthesis
Thyroid Stimulating Hormone (TSH)
Single-chain peptide without disulfide bonds
Produced in response to low serum cortisol, regulator of adrenal androgen synthesis
Adrenocorticotrophic Hormone (ACTH)
Deficiency of ACTH will lead to atrophy of the _____
Zona Glomerulosa
Zona Reticularis
Highest levels of ACTH is between
6:00 - 8:00
Lowest level of ACTH is between
6:00 pm - 11:00 pm
ACTH is increased in:
Addison’s Disease
Ectopic Tumors
Protein-rich meals