Term
| The endocrine system controls body activities by releasing mediator molecules called...? |
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Definition
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Term
| What are the general functions of hormones? |
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Definition
- extracellular fluid
- metabolism
- biological clock
- contraction of cardiac & smooth muscle
- glandular secretion
- immune functions
- growth & development
- reproduction
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Term
| Differentiate b/n endocrine & exocrine glands: |
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Definition
exorine
-secrete products into ducts which empty into body cavities or body surface
-sweat, oil, mucous, & digestive glands
endocrine
-cells in close association w/ capillaries
-secrete hormones into bloodstream (other organs secrete hormones as 2nd function)
-pituitary, thyroid, parathyroid, adrenal, pineal |
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Term
| Describe neurosecretory cells: |
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Definition
- neuron endings near capillaries
- synthesis in neuron bodies
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Term
| hormones only affect target cells with specific membrane proteins called...? |
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Definition
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Term
| Although hormones travel in blood throughout the body, they affect only specific _________ cells. |
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Definition
| target; target cells have specific protein or glycoprotein receptors to which hormones bind |
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Term
| Receptors are constantly being...? |
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Definition
| synthesized & broken down |
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Term
| Synthetic hormones that block the receptors for particular naturally occuring hormones are available as what? |
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Definition
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Term
| The regulation of hormone receptors can be what two kinds of feedback? |
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Definition
- negative feedback (self-limiting)
- positive feedback (explosive)
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Term
| Differentiate b/n down & up regulation for negative feedback: |
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Definition
down-regulation
-excess hormone leads to dec in # of receptors
-receptors undergo endocytosis & degraded
-dec sensitivity of target cell to hormone
up-regulation
-deficiency of hormone leads to inc # of receptor
-target tissue more sensitive to hormone |
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Term
| Describe the up-regulation of positive feedback: |
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Definition
- excess of hormone leads to inc. # receptors
- target tissue more sensitive to hormone
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Term
| hormones that travel in blood & act on distant target cells |
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Definition
| circulating hormones or endocrines |
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Term
| hormones that act locally w/o first entering blood stream |
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Definition
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Term
| local hormone that acts on neighboring cell |
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Definition
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Term
| local hormones that acts on same cell that secreted it |
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Definition
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Term
| What are 2 examples of lipid-soluble hormones? |
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Definition
Steroids
-lipids derived from cholesterol
-progesterone, estrogen, testosterone, aldosterone
thyroid hormones
-tyrosine ring plus attached iodines are lipid-soluble |
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Term
| Describe all the actions of lipid-soluble hormones: |
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Definition
- hormone diffuses through phospholipid bilayer into cell
- attaches to transport protein
- binds to receptor turning on/off specific genes
- new mRNA formed & direct synthesis of new proteins (reserve hormone)
- new protein alters cell's activity
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Term
| What are 2 examples of water-soluble hormones? |
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Definition
amine, peptide, & protein hormones (modified a.a. or a.a. put together)
-serotonin, melatonin, histamine, epinephrine
-some glycoproteins
eicosanoids
-derived from arachidonic (fatty) acid
-prostaglandinis or leukotrienes |
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Term
| Describe all actions of water-soluble hormones: |
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Definition
- cannot diffuse through plasma membrane but are secreted by exocytosis
- act through 2nd messengers
- circulate in free form in blood
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Term
| What has a strong influence on the endocrine system? |
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Definition
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Term
| What is the major integrating link b/n the nervous & endocrine systems? Why is this so? |
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Definition
hypothalamus
- receives input from cortex, thalamus, limbic system, & internal organs
- hypothalamus controls pituitary gland w/ 9 dif. releasing & inhibiting hormones
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Term
| The hypothalamus & pituitary gland (hypophysis) regulate virtually all aspects of what? |
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Definition
| growth, development, metabolism, & homeostasis |
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Term
| anterior pituitary gland is aka |
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Definition
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Term
| List the hormones of the APG: |
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Definition
- human growth hormone (hGH)
- thyroid-stimulating hormone (TSH)
- follicle-stimulating hormone (FSH)
- luteinizing hormone (LH)
- prolactin (PRL)
- adrenocorticotrophic hormone (ACTH)
- melanocyte-stimulating hormone (MSH)
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Term
| The human growth hormone (hGH) is secreted by what? What is it stimulated and inhibited by? |
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Definition
- secreted by somatotrophs
- stimulated by growth hormone releasing hormone (GHRH)
- inhibited by somatostatin & IGF-I
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Term
| The thyroid stimulating hormone (TSH)is secreted by what? What is it stimulated and inhibited by? |
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Definition
- secreted by thryrotrophs
- stimulated by thryrotropin releasing hormone (TRH)
- inhibited by thyroid hormone, dopamine, & somatostatin
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Term
| The follicle-stimulating hormone (FSH) is secreted by what? What is it stimulated and inhibited by? |
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Definition
- secreted by gonadotrophs
- stimulated by Gonadotrophin releasing hormone (GnRH) & estrogen
- inhibited by sex steroids & inhibin
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Term
| The luteinizing hormone (LH) is secreted by what? What is it stimulated and inhibited by? |
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Definition
- secreted by gonadotrophs
- stimulated by Gonadotrophin releasing hormone (GnRH) & estrogen
- inhibited by sex steroids
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Term
| The prolactin hormone (PRL) is secreted by what? What is it stimulated and inhibited by? |
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Definition
- secreted by lactrotrophs
- stimulated by thyrotropin releasing hormone (TRH) & VIP
- inhibited by dopamine
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Term
| The adrenocorticotrophic hormone (ACTH) is secreted by what? What is it stimulated and inhibited by? |
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Definition
- secreted by corticotrophs
- stimulated by corticotrophin-CRH releasing hormone
- inhibited by glucocorticoids
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Term
| The secretion of anterior pituitary gland hormones is regulated by _________ _________ hormones & by ________ _________ mechanisms. |
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Definition
| The secretion of anterior pituitary gland hormones is regulated by hypothalamic regulating hormones & by negative feedback mechanisms. |
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Term
| The anterior lobe of the APG is linked to the hypothalamus via what system and the posterior lobe is derived from what? |
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Definition
- anterior lobe linked to hypothalamus via hypothalamic-hypophyseal portal system
- posterior lobe of gland derived from neural tissue (nerve cell bodies located in hypthalamic nuclei)
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Term
| Hormones are made in the __________, packaged in ________ _________, and transported down the axons to be stored for the release by the ________ _________. |
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Definition
| Hormones are made in the hypothalamus, packaged in secretory granules, and transported down the axons to be stored for the release by the posterior pituitary. |
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Term
| The thyroid hormone is related to what kind of feedback system? Which is oxytocine related to? |
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Definition
- thyroid hormone = negative feedback
- oxytocine = positive feedback
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Term
| ACTH & MSH are derived from what? |
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Definition
| proopiomelanocortin (POMC) |
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Term
| Characteristics of hGH: What is its function, how is secretion inc/dec, what kind of feedback is it, etc. |
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Definition
- acts indirectly on tissues by promoting synthesis & secretion of small protein hormones called insulin-like growth factors (IGFs)
- secretion inc. = sleep, stress, starvation, puberty, excercise
- secretion dec. = obesity, hyperglycemia, pregnancy
- negative feedback
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Term
| Describe 3 types of pituitary gland disorders including what occurs when there is hypo/hyper-secretion during childhood & hypersecretion during adulthood: |
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Definition
- hyposecretion in childhood: pituitary dwarfism (proportional, childlike body)
- hypersecretion in childhood: gigantism (proportional, very tall)
- hypersecretion in adulthood: acromegaly (growth of hands, feet, facial features, & thickening of skin)
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Term
| What produces TRH and what produces TSH? TSH stimulates the synthesis & secretion of what? |
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Definition
- hypothalamus produces TRH
- anterior pituitary produces TSH
- TSH stimulates synthesis & secretion of T3 & T4...(metabolic rate stimulated)
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Term
| What controls gonadotrophs that release FSH? What are the functions of FSH for females & males? |
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Definition
- releasing hormone from hypothalamus controls gonadotrophs that release FSH
- female = initiates formation of follicles w/n ovary & stimulates follicle cells to secrete estrogen
- male = stimulates sperm production in testes
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Term
| What produces LH? What does LH stimulate in females & males? |
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Definition
- gonadotrophs produce LH
- females = secretion of estrogen, ovulation of 2nd oocyte from ovary, formation of corpus luteum, secretion of progesterone
- males = stimulation of interstitial cells of testes to secrete testosterone
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Term
| What is the function of prolactin? What factors increase and inhibit its secretion? |
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Definition
- PRL initiates & maintains milk secrection by mammary glands & inc milk production in breast
- suckling reduces levels of hypothalamic inhibition & prolactin levels rise w/ milk prod.
- thyrotropic release factor inc secretion
- PRL inhibits own secretion by stimulating dopamine release
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Term
| Adrenocorticotrophic hormone (ACTH) controls the production & secretion of what? What stimulates corticotrophs that secrete ACTH & MSH? |
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Definition
- ACTH controls production & secretion of hormones called glucocorticoids by the cortex of the adrenal gland
- hypothalamus releasing hormones stimulate corticotrophs that secrete ACTH & MSH
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Term
| What does MSH do & what increases its release? |
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Definition
- MSH inc. skin pigmentation (exact role in humans unknown)
- hypothalamus releasing hormone inc. MSH release from anterior pituitary by corticotroph cells
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Term
| Posterior pituitary gland is aka? |
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Definition
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Term
| Characteristics of posterior pituitary gland & the two hormones made by the hypothalamus that it stores & releases: |
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Definition
- consists of axon terminals of hypothalamic neurons
- does not synthesize hormones
- 2 hormones: oxytocin (OT) & antidiuretic hormone (ADH)
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Term
| What are the functions of oxytocin? |
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Definition
- two target tissues (neuroendocrine reflexes): mammary glands & uterus
- during delivery baby's head stretches cervix, OT enhances uterine muscle contraction to aid delivery
- after deliver positive feedback ceases, OT stimulates contraction of uterus, expulsion of placenta, & ejection of milk (nursing baby stimulates OT release)
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Term
| What is the function of ADH or Vasopressin (what does it stimulate?) & what is ADH primarily controlled by? |
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Definition
- stimulates water reabsorption by kidneys & arteriolar constriction to dec. urine volume & conserve body water (dec. urine production, dec. sweating, inc. BP)
- primarily controlled by osmotic pressure of blood
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Term
| What happens to ADH when someone is dehydrated? Overhydrated? |
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Definition
- dehydrated = ADH released
- overhydrated = ADH inhibited
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Term
| A patient that is involved in a car acident starts to feel very thirsty. Which could be a cause of these symptoms? |
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Definition
| increased plasma osmolarity |
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Term
| What disfunction of the posterior pituitary causes hyposecretion of ADH? What symptoms does it cause and what are features are associated with it? |
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Definition
- hyposecretion of ADH = diabetes insipidus
- excretion of large amts of dilute urine & subsequent dyhydration & thirst
- associated features: visual field loss, optic atrophy, papilledema, other pituitary hormone abnormalities
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Term
| What disfunction of the posterior pituitary causes ADH hypersecretion? |
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Definition
- after neurosurgery, trauma, or secreted by cancer cells
- syndrome of inappropriate ADH secretion (SIADH)
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Term
Where is the thyroid gland located? Histologically, the thyroid consists of thyroid follicles
composed of ________ ____, which secrete the thyroidhormones __________ & _______________, & parafollicular cells, which secrete __________. |
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Definition
| Located just below larynx & has 2 lobes. Histologically, the thyroid consists of thyroid follicles composed of follicular cells, which secrete the thyroid hormones thyroxine (T4) & triiodothyronine (T3), & parafollicular cells, which secrete calcitonin (CT). |
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Term
| Describe the formation, storage, & release of thyroid hormones (TH): |
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Definition
- synthesized from iodine & tyrosine w/n large glycoprotein molecule called thryroglobulin
- transported in blood by plasma proteins; mostly thyroxine-binding globulin (TBG)
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Term
True or False:
T4 is ten times more active than T3 and peripheral tissues convert T3 to T4.
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Definition
FALSE
T3 is ten times more active than T4 and peripheral tissues convert T4 to T3. |
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Term
| What is the function of thyroid hormones T3 & T4? |
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Definition
- respobnsible for metabolic rate, calorigenic, synthesis of protein, breakdown of fats, use of glucose for ATP production
- maintenance of blood pressure
- regulation of tissue growth
- development of skeletal & nervous systems
- reproductive capabilities
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