Hormones Flashcards
Intracellular signaling
within cell
CDKs
cAMP
inter cellular signaling
between cells
growth factors (PDGF)
neurotransmitters
hormones
types of signalling
inter cellular
intra cellular
between organisms
local signalling molecules
- Secreted into extracellular fluid
- Travel by diffusion
- Short lived
- Very local effects
- Histamine, neurotransmitters
pheromones
Longer distance
Signal other individuals
2. Molecules travel by air
3. Sensed by vomeronasal organ
hormones
transported around body by blood Produced by endocrine system Endocrine glands/cells Some neurons (secretive neurons) Delivered by blood (diffuses in) and interstitial fluid received by target cells
target cells
. Cells with receptors for that specific hormone
intracellular receptors
Bind lipid Hormones like steroids
Testosterone and thyroid hormones
Often affect promoters regulating transcription
Anterior Pituitary regulated by
Hypothalamus
Hypothalamus
monitors hormone blood levels
Neg. Feedback: Anterior Pituitary hormones
Low levels of hormones cause hypothalamus to signal Anterior Pituitary via secretory neurons
Neurons make releasing hormones (_RH) that signal the anterior pituitary to begin secreting stimulating hormones (_SH)
releasing hormones
signal the anterior pituitary to begin secreting stimulating hormones (_SH)
Stimulating hormones
also called Tropins
are hormones that travel to an organ
Thyroid function Negative Feed back example
Hypothalamus monitors blood levels of thyroid hormones (T3/T4)
Low levels of T3/T4 cause hypothalamus to make releasing hormones (TRH) that signal the anterior pituitary to begin secreting (TSH ) thyroid stimulating Hormone
TSH binds to receptors in thyroid gland causing it to produce T3 & T4
T3/T4 feed back to shut down hypothal. & pit
membrane receptors
Membrane Receptors
Bind peptide/protein hormones
Binding produces 2nd messenger mols. Like cAMP
cAMP initiates chain reaction
resulting series of chem. rxns is called a cascade
ex. glucagon
pancreatic hormones
Hormones produced in Pancreatic Islets
2 types of cells in islets
1) alpha cells = glucagon
2) beta cells = insulin
glucagon=
peptide hormone
Polar
Binds to membrane receptor
low blood glucose process
Low blood glucose triggers alpha cells
Glucagon produced, binds to liver cells
Cascade causes breakdown of glycogen into glucose
High blood glucose levels = neg. feedback
high blood glucose process
High blood glucose levels trigger beta cells
Produce insulin
Insulin causes cascade resulting in uptake of glucose
(only hormone to do this)
Low glucose levels = Neg. feedback
what does insulin target and promote
Targets skeletal muscle, fat & liver cells
Promotes: protein, fat & glycogen synthesis
Diabetes mellitus
Cells do not take up glucose properly
Failure to transduce signal
Diabetes mellitus type
one
autoimmune attack on Beta cells (juvenile onset diabetes)
Diabetes mellitus type
two
target cells ignore insulin
Beta cells constant production of insulin = fail
Insulin shots required
Caused by genetics & obesity
hormone regulation
1) Antagonistic pairs
2) Negative Feedback –
3) Positive Feedback –
Antagonistic pairs
opposing functions
Ex insulin and glucagon
negative feedback
increasing end-product shuts down system
positive feedback
– increasing end-product encourages more production
Have some want more
Positive Feedback example posterior pituitary
Oxytocin triggers uterine contractions
And uterine contractions signal hypothalamus to make MORE oxytocin
Positive Feedback example posterior pituitary PROCESS
Oxytocin produced in neuron cell bodies within the hypothalamus
It is then sent down axon to posterior pituitary where it is released and diffuses into blood
Blood carries oxytocin to uterus
Why do intracellular receptors need Carrier proteins in blood
Because they are hydrophobic and lipids in water clump up so need to bind to get around
Difference between peptide/protein hormones and lipid hormones
Peptide/protein hormone bind membrane receptors but Lipid hormones can diffuse through cell membrane (they are non-polar) to Intracellular receptors
