Exam 9: March 20-24 Flashcards
What is a withdrawal response spinal reflex?
involuntary contraction like when something is too hot
we have to have the threshold reached to get the involuntary response from our spine rather than wait and have our cerebral cortex response
we can’t inhibit the extensor directly because it’s a skeletal muscle but we need to inhibit the motor neuron for the extensor so our flexor can do its job
contraction: flexor - contralateral extensor
relax: extensor - contralateral flexor
where is smooth muscle located?
1) digestive tract lining
2) vessels
3) urogenital tract
4) glands
what does smooth muscle do in digestive tract lining, vessels, urogenital tract and glands?
1) digestive tract lining: to squeeze space and change volume and pressure to move things through digestive system
2) vessels: to change blood pressure - can have different BP in each of your arms by changing the pressure in the vessels
3) urogenital tract: to urinate and reproductive components
4) glands
how do smooth muscles contract?
3D movement/contractions
the actin is connected via dense bodies*
what are dense bodies/what do they do?
actin in smooth muscles is connected via dense bodies
instead of having linear pull with z lines like in skeletal muscles you get a radial pull with our dense bodies
instead of pulling in one line, you extend in a circular motion like an octopus playing tug o war – the radial pull is what you need because you need a 3D tension
is there tropomyosin in smooth muscles?
tropomyosin is associated with smooth muscle but it doesn’t block
it’s always there but it’s always allowing myosin to interact with actin
there’s no troponin associated with the tropomyosin
do smooth muscles depend on calcium?
you still need Ca in the cytosol for a contraction even though there’s no troponin associated with tropomyosin
how do you increase calcium levels in smooth muscles?
smooth is controlled by autonomic nervous system – NT again are what get Ca to increase
unlike skeletal where the only thing that can control it is somatic efferents
with smooth muscle you can have endocrines that can cause contraction because they’ll bind to chemically gated channels that will allow Ca to come in
what are pacemakers?
pacemakers can also impact smooth muscles by setting up a regular pattern
they can trigger a regular activity of that muscle
do chemicals impact smooth muscles?
yes
how does stretch impact smooth muscles?
some of our muscles as they get stretch opens channels and causes movement due to mechanically gated channels
what is calmodulin?
a protein in smooth muscle that is activated by calcium = calcium modulated protein
what happens when calcium binds to calmodulin?
binding of Ca causes a shape change and activates it
activated calmodulin goes and activates myosin light chain kinase
myosin light chain kinase impacts myosin by doing equation 1 and giving myosin energy by phosphorylating myosin - myosin needs ATP
myosin deflexes and reaches out to do another pull
actin is radially arranged and gives you a 3D pull
what does myosin light chain kinase do?
it phosphorylates myosin to give it ATP
the relaxed position is when myosin is in the “flexed” position so we need to energize it so it can deflex and do another pull to get CBC
actin is radially arranged so you get a 3D pull by combining a bunch of different linear pulls in different directions
does smooth muscle have a sarcoplasmic reticulum?
no
you need to get rid of Ca in the cell to get a relaxation
smooth muscles doesn’t have an SR so Ca is coming from outside the cell into the cytosol so we have to pump it back out of the cell
what happens during a smooth muscle relaxation?
1) pump Ca out of the cell since there’s no SR
decreased [Ca] means that calmodulin won’t be activated and will return to inactive form
w/o active calmodulin, myosin light chain kinase also becomes inactive and we no longer have the “reach out” part of CBC
2) get rid of ATP bound myosin heads with myosin light chain phosphatase
what are the two things that need to happen to get a smooth muscle relaxation?
1) pump Ca out out of the cell to deactivate calmodulin
2) get rid of any myosin heads that have ATP bound to them
what is the relaxed position of smooth muscles?
with the myosin heads in the flexed position
what does myosin light chain phosphatase do?
gets rid of ATP energy without resulting in movement
it makes sure all the myosin heads are in the flexed position but without doing the pull to get them there
aka you use the ATP energy to reach out and grab on to be in the flexed position BUT there’s no pull because phosphatase takes the left over energy so you can’t do the pull
how does the endocrine system communicate?
blood carried communication
how fast does the endocrine system work?
slower because it travels over farther distances via the blood so you see the results LATER
does the speed that the endocrine system work at make sense?
yes!
in sympathetic nervous system you get the NT there quickly and get an immediate response like heart rate change because you’re in fight or flight and need to react quickly
adrenal medulla releasing epinephrine in our system kicks in later because it’s slower
how long do endocrine system effects last?
longer lasting effect
if we’re studying and roommate walks in and scares you you’re heart rate will go up really quickly but adrenaline rush will stay around longer even though your heart rate will go back down
how is the endocrine system regulated?
negative feedback regulation
we need to shut down the process of a certain endocrine being released
what is the key of the endocrine system?
the messengers themselves are the key to the system – it’s called the endocrine system not the glandular system – you need a bunch of messengers to get a gland to work
what varies between endocrine messengers?
messengers have different production
they types of endocrines are determined by how they’re made
binding of ligand to the receptor is determined by shape and charge which is determined by how the endocrine is put together
what are the types of endocrine messengers?
1) amines
2) steroids
3) peptides
what is the structure of amines? what are they all derived from?
they all have cyclohexane rings because they all come from the same amino acids
they’re all derived from tyrosine!
if you become tyrosine deficient you’ll wipe out this class of endocrines
they’re polar (except T3 and T4)
what are types of amine endocrine messengers?
1) T3/T4
2) dopamine
3) epinephrine and norpeinephrine
what are T3 and T4?
amine endocrine messengers
produced by the thyroid gland
they’re different because they have two rings which tips them from being polar to non polar
non polarity is important because they are going to have problems traveling through polar plasma
what is dopamine?
amine endocrine messenger
it’s a neurotransmitter in our bioamine group but here it’s acting as an endocrine within our mammary gland component
what are epinephrine and norepinephrine?
amine endocrine messengers
the only difference between the two is a methyl group so they act pretty similarly
fight or flight
what’s the structure of steroids?
they’re all derived from cholesterol
aka all of them have a series of carbon rings
what is the polarity of steroids?
they’re all derived from steroids which is amphipathic, however it’s primarily no-par
so all steroids are nonpolar
they have problems traveling within the blood plasma!
what are types of steroids?
1) cortisol
2) aldosterone
3) testosterone/estrogen
4) placental endocrines
what is cortisol?
steroid
comes from cortex of the adrenal gland
regulates stress levels
what is aldosterone?
steroid
released from adrenal gland
regulates sodium levels
what are testosterone/estrogen?
sex steroids
what are placental endocrines?
steroids
placenta is the structure that allows for exchange between mom and fetus
majority of the encodrines created by placenta are in the steroid category
what are peptides?
a group of endocrine messengers
they’re just small proteins
they largest group of endocrines
how are peptides made?
they’re created as proteins
they get made with too many AA in the string so they’re made too big - when this happens they can’t do their job
that’s okay because we want them to do their job outside in the system, not inside the cell that’s making them aka it’s a safety mechanism
what is a prohormone?
it’s a safety mechanism on the protein, specifically peptides, we refer to it as prohormone because it’s initially inactive
they can later be activated
how are peptides transported?
they’re proteins that are made with too many AA so they can’t just get sent through the PM
we have to put them in a vesicle that we can exocytose so we can secrete the endocrine into the body
once the endocrine is in the vesicle we can activate the prohormone because they’re protected
what happens to peptides before they’re needed in the body?
endocrines sit in vesicles until we need them just like how Ach waits in neuromuscular junction waiting to be released once they’re needed
what are endocrines?
ligands
what is the most important characteristic of endocrines?
they’re ligands so polarity is key
ligands fall into nonpolar or polar which determines which types of receptors in terms of location that they can bind to
nonpolar ligands can bind to intercellular receptors
polar ligands bind to membrane bound receptors
how can endocrines be disrupted?
we can disrupt endocrines by messing with their synthesis or release
if you take cholesterol you lose all the steroid or if you take out tyrosine you lose all the amines
if you’re membrane bound then to can exocytose or endocytose receptor to change response but with intercellular you can only catabolize or anabolize the receptor
what is clearing?
endocrines are always moving through the blood so if you make changes to the blood you effect the endocrines
endocrines can be removed from the blood by our kidney
this is how pregnancy sticks work!
where is the pituitary gland located?
it’s attached to the brain but it’s not part of it
it’s connected to the hypothalamus by a hallow tissue stock called the infundibulum = connective stock
what’s another word for pituitary?
hypophysis