Unit 1A Flashcards
What are true hormones?
-chemical signaling molecules secreted by ductless gland
How are true hormones transported
They are transported through the blood they exit the gland, diffuse into intestinal space, and are then transported
How do true hormones work?
The responsive target cells contain specific hormone receptors on plasma membrane or inside cell and then hormone binding triggers a response
What can true hormones do to the cell?
-cause changes in ionic membrane permeability
-can inhibit or trigger enzymatic activity
- can activate or inhibit specific genes
What kind of cells can true hormones target?
Cells and tissues that are far away as long as they have receptors on membrane or within cell
What are examples of true hormones?
-thyroid hormones
-growth hormones
What are local hormones?
Signaling molecules that don’t circulate in blood
What are the two types of local hormones?
autocrine and paracrine
What are autocrine hormones?
Hormones that effect same cell where the messenger was formed (binds to the same cell it was released from)
What are paracrine hormones?
Hormones that effect neighboring cells
What are examples local hormones?
eicosanoids and prostaglandins
What are eicosanoids?
a primary type of local hormone formed with fatty acids within the phospholipid bilayer of the membrane
What are prostaglandins?
- A diverse group of widely released eicosanoids that are synthesized by most tissues in the body.
- most stimulate pain, fever, and inflammation by increasing the inflammatory response.
What are NSADS
Medicine that interferes with prostaglandins by inhibiting their formation,
What are similarities between true and local hormones?
-both are signaling molecules that must bind to a receptor to cause a response
What are the three ways hormones can be secreted?
-humoral stimulation
-hormonal stimulation
- nervous stimulation
What is hormonal stimulation?
When a gland releases its hormone in response to another hormone binding to it causing a cascade effect
What are examples of hormonal stimulation?
-t3
-t4
-tsh
How does TSH work?
-the anterior pituitary releases TSH which binds to the thyroid gland stimulating it to release TH (brain, blood, thyroid gland)
What is humoral stimulation?
when a hormone is released in response to changes in blood levels of a nutrient like glucose or ion like calcium
What is a prime example of humoral stimulation?
Blood glucose levels?
How is blood sugar regulated
-through a negative feedback loop
- blood glucose levels increase stimulating the pancreas to release insulin, and released insulin causes blood sugar to go down
What is nervous stimulation?
When a hormone is released in response to direct nervous stimulation
Which type of stimulation is the most effective?
nervous stimulation
Where does nervous stimulation stem from?
medulla in the adrenal gland
What are examples of nervous stimulation
norepinephrine and epinephrine
How do norepinephrine and epinephrine work?
- the sympathetic nervous system is activated, sympathetic preganglionic axons stimulate the adrenal medulla to release epinephrine and norepinephrine, epinephrine and norepinephrine are released from the adrenal gland (brain, spinal cord, preganglionic axon, adrenal gland
What are the two types and three classifications of hormones
-Water soluble and non-water soluble
-proteins
-steroids- biogenic amines
What are biogenic amines?
-hormones derived from amino acids
-water-soluble except for thyroid hormones (thyroid hormones are lipid soluble)
What are examples of biogenic amines?
-thyroid hormones
-catecholamines
- epinephrine
-norepinephrine
- dopamine
What are protein hormones
- chains of amino acids like peptides, polypeptides, and glycoproteins
- water soluble
What are glycoproteins?
Proteins with sugars attached
What are examples of proteins hormones?
ADH
insulin
glucagon
What is ADH?
antidiuretic hormone
What are steroid hormones?
- derivatives of cholesterol
-lipid soluble
What are examples of steroid hormones?
-testosterone
-estrogen
-progesterone
Which hormones are water soluble?
-biogenic amines except for thyroid hormones
-proteins
Which hormones are lipid soluble?
- steroid and thyroid hormones
Which type of hormone has a longer 1/2 life?
lipid-soluble hormones
How do lipid-soluble hormones travel?
-mostly bound to water-soluble carrier proteins in blood with a small concentration dissolved in plasma to protect it from water
-unbinds when it gets to tissues so it can diffuse out of the blood and interact with target cells
What type of hormones can interact with target cells?
unbounded/ free hormones
How do lipid-soluble hormones communicate?
- unbound hormones cross the plasma membrane binding to intracellular hormone response complexes located inside the cell (either nucleus or cytoplasm)
- hormone-receptor complex interacts with hormone-response element on DNA initiating transcription of specific genes
- transcription and translation form new proteins and cause changes in cell
( lipid soluble, intracellular receptors, DNA and HRE, transcription + translation, cellular product)
*image to go along with this in slides
What is an HRE
-hormone response elements
-where hormone response complexes can park and initiate transcription
- made of strands of DNA
How do water-soluble hormones travel?
travel unbounded/ free in plasma
How do water-soluble hormones communicate?
-target cell must have membrane-bound receptors for hormone to bind to
-since it binds outside cell it needs an intracellular messenger (2nd messenger) to make an effect
- the effect depends on intracellular 2nd messenger
How do signal transduction pathways work?
-hormone binding on plasma membrane can activate g-protein
- results in the binding of gtp instead of gdp
- the activated g-protein then travels along the inside of the membrane activating or inhibiting other intracellular enzymatic cascades
How does the adenylate cyclase signal transduction pathway work?
- GDP is bumped and GTP binds to a g-protein to activate it
- activated g-protein travels along the plasma membrane after being released from the receptor.
- activated g-protein activates plasma membrane enzyme (adenylate cyclase) and uses ATP to generate cAMP
- cAMP serves as a second messenger and activates protein kinase A enzyme by binding to it
- Protein Kinase A is a phosphorylating enzyme that adds a phosphate to other molecules activating or inhibiting them
- a cascade effect is brought on by protein kinase A
*image to go along with this in slides
How does a phospholipase C signal transduction pathway work?
- activated g-protein binds to phospholipase c and activates it
- activated phosphorylase c splits Pip2 into IP3 and DAG
3a. IP3 leaves the membrane and stimulates the endoplasmic reticulum causing Ca2+ amplification
3ai. Ca2+ can then act as a third messenger or have a direct effect
3b. DAG binds and activates protein kinase C
4a. Calcium acts as a third messenger where it binds to calmodium so it can be used later to turn other kinases on and off
4b. Calcium binds to ion channels to cause changes in membrane potential
*image in slide
What is up-regulation?
-increases the number of hormone receptors on a cell in order to increase sensitivity to a hormone in response to low levels of that hormone in the blood
- less fish in a pond you need more poles to catch one
*image in slides
What is down-regulation?
- decreases the number of hormone receptors on a cell in order to decrease sensitivity to the hormone in response to high levels of that hormone in the blood
- more fish in a pond you need less poles to catch one
*image in slides
When do up and down-regulation occur?
with changes in cell cycle, cell activity, hormone levels, or development
What is a synergistic hormone interaction?
hormones work together to have a greater effect
-1+1=3
What are examples of synergistic hormone interactions?
estrogen and progesterone
What is a permissive hormone interaction?
- When the first hormone allows for the action of the second hormone
- think of permission
What is an antagonistic hormone interaction
-When one hormone causes the opposite effect of another hormone?
1-1=0
What is an example of a permissive hormone interaction?
-prolactin and oxytocin (oxytocin’s milk ejection can only happen after prolactin’s milk generation)
What is an example of a permissive hormone interaction?
-prolactin and oxytocin (oxytocin’s milk ejection can only happen after prolactin’s milk generation)
What is an example of an antagonistic hormone response?
insulin and glucagon (glucagon raises blood sugar and insulin lowers it)
What are hormone interactions?
when different target cells have different types of receptors which means they can bind simultaneously and these interactions can produce different effects
