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endocrine exam 1 > introduction/overview > Flashcards

introduction/overview Flashcards

1
Q

neuronal intracellular messenger

A

neurotransmitters at synaptic junctions, which act locally

ex: Ach, NE

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2
Q

endocrine intracellular messenger

A

release of hormones from specialized glands or cells into the blood circulation to influence the functions of target cells some distance away (insulin, ACTH, oxytocin)

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3
Q

neuroendocrine

A

secretion of products from neurons that reach the blood circulation and influence the function of target cells distance away (CRH)

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4
Q

paracrine

A

cell secretion products that diffuse into ECF and effect neighboring cells

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5
Q

autocrine

A

cell secretion products that affect function of the same cell by binding to cell surface receptors

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6
Q

cytokine

A

secreted cell proteins that function as autocrines, paracrines or endocrines and often act on a broad spectrum of target cells
(ex: IL, LT, TNF alpha)

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7
Q

acetylcholine mediates communication at _____ and _____ nerve terminals

A

parasympathetic and somatic

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8
Q

norepinephrine mediates communication at ____ nerve terminals

A

sympathetic

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9
Q

NTs are produced both _____ and _____

A

centrally and peripherally

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10
Q

what are the neurohormones secreted from neuroendocrine cells?

A

antidiuretic hormone (ADH/vasopressin) and oxytocin

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11
Q

what hormones do not directly interact with neuronal systems and are not under direct influence of neuronal activity for release?

A

neurohormones

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12
Q

what makes hormones?

A

hypothalamus

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13
Q

hormones reach anterior pituitary through ____ system

A

circulatory

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14
Q

the pancreas releases what hormones into what?

A

insulin (beta cells) and glucagon (alpha cells) into muscle, adipose, and liver

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15
Q

the adrenal medulla is controlled by____ and releases _____ into what?

A

controlled by CNS

releases epinephrine into muscle, adipose, liver

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16
Q

3 groups of hormones based on chemical structure or synthesis

A
  • proteins and peptides (TRH, GH, insulin)
  • steroids (derivatives of cholesterol–testosterone, cortisol, estrogen)
  • derivatives of tyrosine (from thyroid gland T3 & T4 and adrenal medulla–epinephrine and norepinephrine)
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17
Q

protein/peptide hormones are made in the -_____

A

rough ER

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18
Q

preprohormone

A

initially formed protein that is larger than the active hormone

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19
Q

preprohormone is cleaved to form a _____ in ER

A

prohormone

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20
Q

the prohormone is packaged in secretary vesicle in the _____

A

golgi apparatus

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21
Q

with endocrine cell stimulation, hormone and co-peptides are released into extracellular fluid by ______

A

exocytosis

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22
Q

steroid synthesis, storage, and secretion

A
  • little storage of hormone in steroid endocrine cells but there are large stores of cholesterol esters for synthesis of steroid hormones
  • hormone diffuses through cell membrane into EC fluid
  • cholesterol removed from plasma for synthesis, but there is also de novo synthesis of cholesterol from acetate
23
Q

steroids are synthesized from _____

A

cholesterol

24
Q

like ____, steroids are _______ thus cross membrane barriers readily

A

thyroid hormones

lipid soluble

25
Q

____ is needed for formation of thyroid hormones and catecholamines

A

tyrosine

26
Q

how are thryoid hormones formed?

A

by enzymatic action in cytosol/cytoplasm

-synthesized by iodination of tyrosine amino acid on thyroglobulin in follicles within thyroid gland

27
Q

how are thyroid hormones stored?

A
  • no storage in discrete granules
  • large stores of thyroxine (T4) and triiodothyronine (T3) as part of large iodinated protein (thyroglobulin) that is stored in lumens of thyroid gland follicles
28
Q

how do thyroid hormones leave the gland?

A

diffusion through cell membrane

29
Q

thyroid hormones are _____ soluble

A

lipid

30
Q

catecholamines (CAs)

A
  • adrenal medullary and sympathetic nerve hormones
  • epinephrine and norepinephrine
  • formed by enzymatic action in cytosol
31
Q

storage and synthesis of catecholamines

A

taken up into preformed vesicles and stored until secreted by process of exocytosis

32
Q

the cortex of the adrenal gland makes ____

A

aldesterone and cortisol

33
Q

the medulla of the adrenal gland makes

A

epinephrine mostly

a little norepinephrine

34
Q

chromaffin cell secretions

A

epinephrine mostly

a little norep

35
Q

size of hormones required to control most metabolic and endocrine functions

A

super small
1 picogram–> few micrograms
VERY POTENT
rate of daily secretion super small

36
Q

rate of hormonal secretion is mostly controlled by ______ mechanism

A

negative feedback mechanism

37
Q

explain negative feedback

A

endocrine glands over secrete hormones
when too much function/activation of target cell occurs, negative feedback to endocrine gland decreases secretary rate (prevents over-activity)

38
Q

negative feedback helps maintain ____

A

homeostasis

39
Q

surges of hormones also occur with ____

A

positive feedback

ex: LH during ovulation

40
Q

examples of cyclical variations of hormone release

A
  • cortisol

- melatonin

41
Q

how are water soluble hormones transported?

A

(peptides and catecholamines)

-dissolved in plasma and transported from their sites of synthesis/release to target tissues

42
Q

steroid and thyroid hormones circulate in blood mainly bound to ______

A

plasma proteins

-serve as reservoirs (not active)

43
Q

how are hormones cleared from blood?

A

destruction
binding to tissues
excretion via liver (bile) and kidneys

44
Q

hormone-receptor interaction is coupled to _____ that causes a _____ by altering the activity and/or amounts of enzymes, carrier proteins, etc

A

coupled to a signal-generating mechanism that causes a change in intracellular processes

45
Q

different types of receptors

A
  • intracellular receptor (thyroid hormone)
  • ion channel-linked receptor (acetylcholine)
  • G-protein linked/coupled receptor (epinephrine)
  • enzyme-linked/catalytic receptor (insulin)
46
Q

role of second messengers

A
  • cell responses to protein/peptide and CA mediated by second messengers
  • mediate hormone responses through intracellular mechanisms
  • coupling of receptors to SMG systems intracellularly
47
Q

adenylyl cyclase (AC-cAMP)

A
  • hormone-receptor interaction stimulates the CM-bound enzyme adenylyl cyclase
  • stimulation of AC results in synthesis of SMG, cyclic AMP (cAMP) via G protein
  • cAMP activates kinase A (PKA)–> protein phosphorylation that activates/inactivates target enzymes
48
Q

phospholipids and SMG generation

A
  • hormone receptor interaction–> activates CM-bound enzyme phospholipase C (PLC)
  • PLC causes phospholipids in CM to split into SMGs, DAG, and IP
  • DAG activates PKC
  • IP3 mobilizes calcium from IC stores –> enhancing activation of PKC
  • phosphorylation of enzymes by PKC activates or deactivates enzymes mediating hormone responses
  • DAG hydrolyzed to form arachidonic acid, a precursor for PGs
49
Q

calcium-calmodulin system

A
  • hormone-receptor interaction activates calcium channels in membrane–> calcium entry from outside
  • some calcium can be mobilized by IC stores by hormone
  • Ca ions intracellularly, bind with protein calmodulin, forming a complex that alters activity of Ca dep enzymes (myosin kinase) and IC reactions–> phys responses
50
Q

G-protein-independent mechanisms/effects

A
  • involve cGMP
  • cGMP=second messenger that mediates the effects of atrial natriuretic peptide/factor (ANF) and NO without involving G protein–> cause direct activation of guanylyl cyclase to produce cGMP from GTP
  • peptide hormones (insulin/leptin) bind to CM receptors to cause phos of IC receptor sites –> alters enzymatic activity
51
Q

how does insulin produce its effects

A

via activation of large transmembrane glycoprotein insulin receptor having 2 alpha and 2 beta subunits linked by disulfide bonds to form heterotetramer

52
Q

insulin receptor is a _____

A

tyrosine kinase

53
Q

cell responses to ____ and ____ hormones are mediated by stimulating protein synthesis via intraceullar receptors

A

steroid and thyroid

  • hormones enter cells and bind to IC receptors in cytoplasm or nucleus
  • H/R interaction –> conformational change in receptor
  • H/R complex binds to specific sites on DNA strands in chromosomes, resulting in activation of specific genes, transcription and translocation of mRNA to cytosol for protein synthesis
54
Q

down-regulation of receptors can occur due to:

A
  • inactivation of some receptor molecules
  • inactivation of some IC protein signaling molecules
  • temporary sequestration of receptor to inside of cell
  • destruction of receptors by lysosomes
  • decreased production of receptors

endocrine exam 1 (5 decks)

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