Lecture 19 Flashcards
secrete their products (hormones) into the adjacent interstitial fluid or blood vessels, usually in a capillary bed
endocrine glands
Hormones; mediator molecules
secretary products
carries mediators to target cells
vascular system
harbor receptors to specific mediators to carry out required response
target cells
released by axon terminals of neurons into the synaptic junctions and act locally to control nerve cell functions
neurotransmitters
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
secreted by neurons into the circulating blood and influence the function of target cells at another location in the body
neuroendocrine hormones
secreted by cells into the extracellular fluid and affect neighboring target cells of a different type
paracrines
secreted by cells into the extracellular fluid and affect the function of the same cells that produced them
autocrines
peptides secreted by cells into the extracellular fluid and can function as autocrines, paracrines, or endocrine hormones
cytokines
Hormones that trigger biochemical signals upon interacting with receptors on cell surface
Intracellular signaling causes a molecular response (_____).
second messenger system
two groups of receptor hormones with receptors on cell surface
Peptide hormones (Ex: Growth Hormone, insulin)
Small molecules (ex: the Amine-derived Epinephrine)
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
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
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
- Hypothalamus
- Pituitary
- Pineal
- Parathyroid
- Thyroid
- Thymus
- Adrenal
- Pancreas
- Ovaries
- Testes
- Adipose tissue
Proteins and polypeptides chemical structure ?
Ex: ?
anterior and posterior pituitary gland, parathyroid, pancreas
Ex: insulin, glucagon, parathyroid hormone
steroids chemical structure?
EX ?
adrenal cortex, ovaries, testes, placenta
ex: cortisol, aldosterone, estrogen, progesterone, testosterone
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)
- Binds with a specific _______
- Combined receptor protein-hormone enters the ______
- Binds to ____ activating the specific transcription process forming _____
- mRNA diffuses into cytoplasm promoting translation of new proteins
- 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
