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
What is the function of calcitonin?
decrease blood calcium levels
Define the thyroid gland disorder Cretinism.
Thyroid dwarfism
too little secretion of thyroid hormones during fetal development and infancy (first 2 years)
severe forms of mental and physicla retardation in newborn
What is Hashimoto’s disease?
Immune diease that attacks the follicular cells causing hypothyroidism in adults
What is Grave’s disease?
Immune disease that activates the follicular cells to produce a lot of thyroid hormone
What is endemic colloid goiter?
insufficient dietary iodine to make T3 and T4
causes over secretion of TSH by the anterior pituitary gland– excessive activation and overgrowth of the thyroid gland follicles
(happens in certain regions such as desert)
What are the main functions of the parathyroid hormone (4)?
mobilizes calcium and phosphate
decreases calcium excretion
increases phosphate excretion
increases intestinal absorption
How are the effects of parathyroid hormone on cells mediated?
by the cAMP second messanger system
What is the function of calcitonin?
decreases calcium plasma level by
inhibiting osteolysis and osteoclastic bone reabsorption
decreasing calcium absorption by the intestines
decreasing calcium reabsorption by the kidneys
What is hypoparathyroidism?
When the parathyroid is surgically removed (accidentally) causing blood calcium levels to drop low. This causes death in 2 days from tetanus.
What are sokme symptoms of hyperthyroidism?
renal stone formation (calcium) and soft fragile deformed bones
From the medulla of the adrenal gland outward, what are the 3 zona layers in order?
zona reticularis, zona fasciculata, zona glomerulosa
The adrenal medulla is related to the sympathetic nervous system. What are the main functions?
secrete epi and NE, which increase heart activity, vasoconstriction, pupil dilation, cellular metabolic rate
decreases urine output
What does the zona glomerulosa excrete and what effect does it have on the body?
contains aldosterone synthase- secretes mainly aldosterone which increases renal tubular reabsorption of sodium and secretion of potassium in urine
Aldosterone deficiency causes _____ and cardiac toxicity.
hyperkalemia
Excess aldosterone causes ______ and muscle weakness.
hypokalemia
What does the zona fasciculata secrete and what effect does it have on the body?
secrete glucocorticoids, mainly corticosterone and cortisol, plus some androgens and estrogens
glucocorticoids stimulate gluconeogenesis and decrease glucose utilization by the body cells
glucocorticoids also increase blood amino acids & blood fatty acids
anti-inflammatory and important in resisting stress
What does the zona reticularis secrete and what effect does it have on the body?
secretes the male sex steroids androstenedione and DHEA
Secretion of both zona fasciculata and zona reticularis is controlled by the hypothalamic ___ ___ ___ and the anterior pituitary ____ ____.
Corticotropin Releasing Hormone (CRH) Adrenocorticotrophic Hormone (ACTH)
What is Addison’s disease?
hypoadrenalism- autoimmune atrophy or injury of the adrenal glands that causes the inability to secrete sufficient adrenocortical hormones
When talking about Addison’s disease; aldosterone deficiency causes what?
hyponatremia, hyperkalemia, cardiac shock and death
When talking about Addison’s disease; cortisol deficiency causes what?
decrease in body energy mobilization and inability to resist stress leasing to Addisonian Crisis
What is the cause of Cushing’s syndrome?
hyperadrenalism- hypersecretion of the adrenal cortex hormones due to excess ACTH or cortisol secretion by adenomas of the hypothalamus , anterior pituitary or adrenals
What are some symptoms of Cushing’s syndrome?
mobilization of fats- ‘moon face’, ‘buffalo hump’
mobilization of proteins- muscle wasting and weakness
What is the treatment for Cushing’s syndrome?
surgival removal of adenomas, radiation or drugs that block steroidogenesis
What is the cause for Conn’s syndrome?
hypersecretion of aldosterone by a tumor of the zona granulosa cells
What are symptooms of Conn’s syndrome?
excess aldosterone- hypokalemia (causes occasional muscle paralysis), metabolic alkalosis, increased blood volume, hypertension, decreased plasma renin
What is the treatment for Conn’s syndrome?
surgical removal of the tumor or receptor antagonistic drugs
What is the cause for adrenogenital syndrome?
excessive secretion of the androgens androstenedione and DHEA from adrenocortical tumor.
What are the symptoms in adrenogenital syndrome?
in females- virilization, masculinization, beard growth, baldness, clitoris enlargement.
in prepubertal male- early puberty and rapid development of male sex organs
what is the treatment for adrenogenital syndrome?
surgical removal of the tumor
What do the endocrine and exocrine parts of the pancreas secrete?
endocrine- 5 hormones (pancreatic islets of langerhans)
exocrine- digestive enzymes (acini)
The endocrine part of the pancreas secretes 5 different hormones. What are the cell names and the hormones?
alpha- glucagon
beta- insulin & amylin
delta- somatostatin
PP- pancreatic polypeptide
What protein is insulin secreted equally with?
C-protien
What stimulates insulin secretion?
increased glucose, amino acids and fatty acid blood levels after a meal
What does insulin do?
decreases blood glucose levels, increases liver uptake of glucose & storage of excess glucose as glycogen in the liver, increases glucose storage as glycogen in muscles, increases fat synthesis and storage, increases protein synthesis and storage
Glucagon is synthesized by the alpha cells in the pancreas. What stimulates its secretion and what is glucagon’s mechanism of action?
- secretion stimulated bu decreased blood glucose levels, inc blood amino acid levels, or exercise
- glucagon binds to cell membrane receptors that acitvates adenylyl cyclase, cAMP and protein kinase
What stimulates the secretion of somatostatin?
increased blood levels of glucose, fatty acids and GI hormones
What is the role of somatostatin?
inhibts insulin, glucagon and growth hormone secretion
inhibits motility, secretion and absorption in GI tract
What is the range for a normal fasting plasma glucose levels in adults?
80-100 mg/dL
What plasma levels would be indicative of someone with diabetes mellitus?
fasting plasma glucose >110 mg/dL or random level is >200 mg/dL
What test results may be indicative of diabetes mellitus?
impaired glucose tolerance test, glucose in urine, high plasma insulin
What are 6 characteristics of diabetes mellitus?
hyperglycemia, polyphagia, polyuria, polydipsia, glucosuria, asthenia
What occurs in type I diabetics if they inject too much insulin?
Insulin Shock
Why do type I diabetics enter metabolic acidosis without insulin injection?
they will have excessive fatty acid oxidation for energy and the production of keto acids because they glucose being ingested cannot be used
In type II diabetes; why is there an insulin resistance?
fewer insulin receptors or a defect in the insulin signaling pathway
Would a person with type II diabetes (unmanaged) usually have high or low plasma insulin levels?
High because they’re trying to compensate for the receptor resistance
Impaired gucose uptake in type II diabetics can lead to what? at what plasma glucose level?
diabetic coma when plasma glucose levels rise to 1000 mg/dL or more
What are possible treatments for type II diabetics?
weight loss, drugs, beta cell exhaustion
Name 3 drugs used in type II diabetics and what they do?
thiazolidinediones- increase insulin sensitivity
sulfonylureas- increase beta cells insulin release
metformin- suppress liver glucose production
What are metabolic consequences of chronic diabetes?
arterosclerosis, retinopathy, peripheral neuropathy, nephropathy, hypertension
What is insulinoma?
hyperinsulinemia- excessive insulin secretion form an adenoma of the pancreatic islets or from excessive insulin injections
What do granulosa cells produce and where are they located?
estradiol
in wall of ovarian follicle
What do corpus luteum cells produce?
progesterone
What are the functions of estradiol and progesterone?
development of female rep system, bone growth, secondary sexual characteristics
regulate menstrual cycle and sustain pregnancy
prepare mammary glands for lactation
What does the interstitial cells in the testes produce?
testosterone
What do the sertoli cells in the testes secrete?
inhib which surpresses FSH secretion and stabilizes sperm production rates
What does atrial natriuretic peptide that the heart produces do?
lowers blood volume and pressure by increasing sodium and water loss by the kidneys
Where is vitamin D3 produced?
the skin
the liver converts it to calcidiol
What 4 hormones are produced in the liver?
erythropoietin, angiotensin, hepcidin, and calcidiol
What is the active form of vitamin D and how is it made?
calcitriol
skin produces vitamin D3–> liver converts D3 to calcidiol–> kidneys convery calcidiol to calcitriol
What hormone does adipose tissue produce?
leptin
