Lecture 19 Flashcards by Sydney Perry

secrete their products (hormones) into the adjacent interstitial fluid or blood vessels, usually in a capillary bed

endocrine glands

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Hormones; mediator molecules

secretary products

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carries mediators to target cells

vascular system

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harbor receptors to specific mediators to carry out required response

target cells

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released by axon terminals of neurons into the synaptic junctions and act locally to control nerve cell functions

neurotransmitters

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released by glands or specialized cells into the circulating blood and influence the function of target cells at another location in the body

endocrine hormones

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secreted by neurons into the circulating blood and influence the function of target cells at another location in the body

neuroendocrine hormones

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secreted by cells into the extracellular fluid and affect neighboring target cells of a different type

paracrines

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secreted by cells into the extracellular fluid and affect the function of the same cells that produced them

autocrines

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peptides secreted by cells into the extracellular fluid and can function as autocrines, paracrines, or endocrine hormones

cytokines

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Hormones that trigger biochemical signals upon interacting with receptors on cell surface

Intracellular signaling causes a molecular response (_____).

second messenger system

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two groups of receptor hormones with receptors on cell surface

Peptide hormones (Ex: Growth Hormone, insulin)
Small molecules (ex: the Amine-derived Epinephrine)

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Hormones that diffuse across target cell’s plasma membrane to interact with intracellular receptors

these are ______ molecules

Complexes bind to promoter and enhancer DNA elements, affecting gene expression

example?

Steroids – estrogen, progesterone, glucocorticoids

Thyroxine

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which system nervous or endocrine is…

close to site of release
delivers to cells of body
delivers to cells many muscle
takes longer
lasts longer

nervous
endocrine
nervous
endocrine
endocrine

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roles of endocrine system

Regulation of water and ion balance
Response to infection, trauma, stress
Regulating growth and development
Reproduction
Digesting, storing and utilization of nutrients

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Hypothalamus
Pituitary
Pineal
Parathyroid
Thyroid
Thymus
Adrenal
Pancreas
Ovaries
Testes
Adipose tissue

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Proteins and polypeptides chemical structure ?
Ex: ?

anterior and posterior pituitary gland, parathyroid, pancreas

Ex: insulin, glucagon, parathyroid hormone

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steroids chemical structure?
EX ?

adrenal cortex, ovaries, testes, placenta

ex: cortisol, aldosterone, estrogen, progesterone, testosterone

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amines chemical structure?
examples?

derivatives of amino acid tyrosine

thyroid, adrenal medulla

ex: Thyroxine, triiodothyronine, epinephrine, norepinephrine

Polypeptides; ________ amino acids (AKA; proteins)
Peptides ____ amino acids

100 or more
<100

in endocrine cells the polypeptides and peptides are made in the ________ and can also form ______ and _____

ER
prehormones (1 step away)
pro hormones (2 seps away)

from ER they are moved to ________ and packages into ______ to be stored in the _______.

They can then be released by _____ when they are needed.

Golgi aparatus
vesicles
cytoplasm

exocytosis

steroid production is from ______.

it is not stored but produced when needed from circulating ______ in plasma

cholesterol
cholesterol

amine hormone production is derived from _____ from ______ and ______

stored in _____ as _______
makes _______ when needed

tyrosine
thyroid and adrenal medulla

thyroid gland
thyroglobulin
epi and norepinephrine

Circulating hormones combine with __________ which slowly releases the hormones to the target tissues

plasma proteins (thyroxine-binding globulin)

amine hormones Epi, norepinephrine are formed within the ________. more _____ formed. _______ stored within vesicles and released through exocytosis when needed Circulate free or combined with other substances

adrenal medulla epinephrine Catecholamines

hypocalcemia is a

negative feedback loop

timing for mechanisms

Some exert their effects immediately while others may take weeks to months

amounts for mechanisms

active in very small quantities

half live for mechanisms

vary catecholamines (free) minutes to hours steroids –hours thyroxine- days

Hormone activity at the target tissues remains under constant control primarily through ________ - Hormone levels themselves - Reached effective target tissue activity Feedback can occur at any of the steps, synthesis, packaging etc

negative feedback system

Cyclical variations primarily due to _____ control - Seasonal - Developmental stages - Age - Daily cycle - Sleep-wake

neural

Hormone itself can cause continued secretion which would be ____________ example?

positive feedback luteinizing hormone - stimulated by effects of estrogen on the anterior pituitary - works to stimulate more estrogen - estrogen stimulates more LH until level is reached

transport of Water soluble hormones and what are they

peptides and catecholamines dissolve and move freely through the plasma to their target tissues

transport of protein bound hormones example

cleared slowly from the plasma steroids, thyroid small % are free in plasma remain inactive in circulation until they dissociate from the protein molecule

Metabolic Clearance is controlled by ?

rate of secretion rate of removal (metabolic clearance rate)

mechanisms of clearance are

tissue destruction tissue binding liver excretion into bile kidney excretion into bile kidney excretion in urine

Most mechanisms will affect target tissue by forming a __________ Altering the function of the receptor itself It is the activated receptor that initiates the hormonal effects Examples of Hormone Receptor Interactions - Intracellular Signaling - Ion channel linked receptors - G protein-linked hormone receptors - Enzyme linked hormone receptors - Intracellular Hormone Receptors and activation of genes

hormone-receptor complex

Second messenger mechanisms examples include Therefore: depending upon the hormone, the mechanism (processes) of how it alters the function of the target tissue can be different

Adenyl cyclase-cAMP second messenger system Cell membrane Phospholipid system Calcium-Calmodulin system

Each cell has thousands of receptors - Down regulated or upregulated Located at various sites of the cell - Membrane-peptides, catecholamines - Cytoplasm-steroids - Nucleus-thyroid hormones Once bound to their specific hormone the activated receptor then initiates the hormones effects either ___________ or by __________

directly (primary) a secondary messenger system

intracellular signaling includes ____________ examples include - Neurotransmitter substances combine with receptors in the postsynaptic membrane - Ion channel–linked receptors open or close ion channels - Movement of these ions (electrochemical gradient) through the channels cause the subsequent effects on the postsynaptic cells Most of the hormones that work by this mechanism (ie. Opening or closing ion channels) do this indirectly by ________________

ion channel linked receptors coupling with G protein–linked or enzyme-linked receptors

G protein–linked receptors Cell membrane proteins called ________ Hormones bound to these proteins to facilitate their effects by either increasing or decreasing the activity of intracellular enzymes Inhibitory G proteins (______) Stimulatory G proteins (_______)

heterotrimeric GTP-binding proteins (G proteins) Gi proteins Gs proteins

Enzyme-linked receptors Some activated receptors function directly as enzymes or are associated with enzymes that they activate Enzyme-linked receptors bind with the hormone on the _______ of the cell membrane Hormone binds to the_______ part of the receptor, activating an enzyme inside the cell membrane Ex: ____________

outside extracellular Leptin-release from adipocytes regulates appetite and energy balance

Intracellular Hormones and Gene Activation 1. Adrenal, thyroid hormones, vitamin D, bind with _______ inside the cell 2. Readily cross the cell membrane and interact with receptors in the ________ 3. Activated hormone-receptor complex binds with a specific regulatory (promoter) _______(hormone response element) 4. Either activates or represses_______ of specific genes and formation of the messenger RNA (mRNA) if the appropriate combination of gene regulatory proteins is present 5. The new _____ alter the cell’s activity and cause responses typical of that hormone

protein receptors cytoplasm or nucleus sequence of the DNA transcription proteins

How Hormones Act on Genetic Function (Steroid) 1. Binds with a specific _______ 2. Combined receptor protein-hormone enters the ______ 3. Binds to ____ activating the specific transcription process forming _____ 4. mRNA diffuses into cytoplasm promoting translation of new proteins 5. The new ______ alter the cell’s activity and cause responses typical of that hormone

receptor protein nucleus DNA mRNA proteins

Hormones Act on Genetic Function (Thyroid Hormones) Increase _______ by binding with receptors –subsequently activating _______ that control specific gene promoters

gene transcription transcription factors