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What is the second major controlling system of the body?
Endocrine System
What is the main purpose of the endocrine System?
to maintain delicate balance of homeostasis
What signals does the Endocrine system use?
chemicals = hormones
What pathways do the E.S use?
blood transport or Extracellular fluid
What is the speed the info travels in the E.S?
slow
Is the duration of effects in the Endocrine System short or long?
they can be short or long lasting
What are the targets of the Endocrine system?
many cells throughout the body
What must be present in order for hormones to bind to a target cell?
specific hormone recpetors
What is the mechanism of communication Endo System uses?
signal transduction
How does signal transduction work?
stimulus is needed and then a trigger of chain reactions within the cell occurs
What kind of feedback does the Endocrine System have?
positive and negative feedback
T or F: one hormone produce different reactions in different cells
true
Negative feedback
ends the reaction/process that is occuring
positive feedback
keeps going and amplifies reaction/process
hormones
signaling molecules that are carried by bldstream, they bind to receptors on cells to elicit a response
target organs
organ that responds to a hormone
endocrine gland
ductless
release product right into bldstream
exocrine glands
haves ducts
releases product into a specific location
ex: salivary
hyposecretion
production at a slow rate/insufficient quantites
hypersecretion
production at an excessive rate overly large amount
tropic hormones
hormones which stimulate the release of other hormones
5 Endocrine Glands
pituitary
thyroid
parathyroid
adrenal
pineal
What kind of organ is the hypothalamus?
neuroendocrine organ
3 organs that have exocrine and endocrine fucntions
pancreas
gonads
placenta
Examples of other tissues/organs that produce hormones
adipose cells, thymus, cells in walls of small intestine, stomach, kidneys, and hearts
3 chemical groups of hormones
peptide
steroid
amine
T or F: peptide hormones aren’t the majority type of hormone
false
What are petides made up of?
chains of amino acids
Peptides are ___soluble therefore easily transported in blood plasma
water
Where are the hormone receptors for peptides located?
on the cell surface
2 examples of Peptide hormones
insulin and growth hormone
What are steroid hormones synthesized from?
cholestrol
Steroids are ____ soluble so they easily diffuse through cell membrane
lipid
Where are the receptors for steroid hormones located?
on nucleus or in cytoplasm
Steroid hormones can also activate …..
gene transcription
examples of steroid hormones
estrogen, testosterone, cortisol
What are amine hormones syntehsized from?
from amino acid tyrosine (single amino acid)
T or F: amine hormones can either be water or lipid soluble
true
examples of amine hormones
epinephrine, thyroxine
three types of signaling (distance)
endocrine
autocrine
paracrine
How far do autocrine signaling goes?
most local, acts on the same cell that secretes it
How far does paracrine signaling go?
only influences nearby cells
diffuses locally in ecf
degrades quickly
how is histamine release an example of paracrine signaling?
release of histamine caues smooth muscle in nearby bld vessel to relax which brings in more bld
Can water soluble hormones pass through the cell membrane?
no
Can lipid soluble hormones diffuse through the cell membrane?
yes
Where are the receptors for lipid soluble hormones located?
in the nucleus or cytoplasm
how hormones work (3 steps)
endocrine (secreting) cell sends the signal
hormone receptor
cell responds
3 types of hormone receptors
cell surface receptors
intracellular (cytoplasm) receptors
nuclear
What types of hormones bind to nuclear receptors
steroid amine
what types of hormones bind to intracellular receptors?
steroid amine
What types of hormones bind to cell surface receptors?
proteins, peptides, amines
amino acid-based hromones exert their effects through _____ systems
second messenger
two types of second messenger systems
cyclic AMP
PIP2-Calcium
5 steps of Cyclic AMP signaling mechanism
hormone binds to receptor
receptor activate G protein
gprotein activated/inhibits effector enzyme adenylate cyclase
adenylate cyclase converts ATP to cAMP
cAMP activats protein kinases that phosphorylate other proteins
What happens to the phosporylated proteins during Cyclic AMP signlaing?
they can either be activated or inactivated
in order to stop cAMP signaling, cAMP has to be degraded. Which enzyme degrades it?
phosphodiesterase
5 steps of direct gene activation
steroid hormone diffuses through ECF and binds to intracellular receptor
receptor hormone complex enters nucleus
receptor hormone complex binds a specific DNA regio
binding start transcription of the gene to mRNA
mRNA directs protein systhesis
What two things are needed to create a receptor hormone complex?
steroid hormone and receptor protein
3 types of endocrine gland stimuli
humoral
neural
hormonal
What is a humoral stimuli?
changes in blood level of ions and nutrients which directly stimulate secretion of hormones
Example of humoral stimuli
decline blood calcium concentration stimulates parathyroid glands to secrete parathyroid hormone
What is a nueral stimuli?
nerve fibers that stimulate hormone release
example of nerual stimuli
sympathetic nervous system fibers stimulate adrenal medulla to secrete catecholamines
WHat is a hormonal stimuli?
when hormoes stimulate other endocine organs to release their hormones
Hypothalamic hormones stimulate the release of most ____ hormones
anterior pituitary
Anterior pitutary hormones then sitmulate ____ to secrete more hormones
targets
What is the endocrine organ feedback loop?
hyptohalmaic- pitutitary-target
T or F: hormones from final target organs inhibit release of anterior pituitary hormones
true
T or F: nervous system can make adjustments to hormone levels when needed
true
nervous system can also ___ normal endocrine glands
override
3 factors of target cell activation
blood levels of hormone
relative number of receptors on/in target cell
strength of binding between receptors and hormone
can the amount of hormones influence number of receptors for that hormone?
yes
up-regulation
target cells form more receptors in response to low hormone levels
down-regulation
target cell lose receptors in response to high hormone levels
hormones can circulate the blood in two ways
free or bound
what hormones travel the blood binded to plasma proteins?
steroidsn and thyroid hormones