Exam 10: March 27-31 Flashcards
does hypothyroidism have negative feedback?
no negative feedback
what are symptoms of hypothyroidism?
- increased TSH
- over-stimulated follicular cells
- enlarged gland = goiter
what is another name for hyperthyroidism?
Grave’s disease
what is hyperthryoidism caused by?
it’s an autoimmune disease
when the immune system causes problems, it’s called a self immune
caused by an antibody
proteins that are normally there to identify our pathogen’s antibodies are instead binding to TSH receptors and causes our TSH to act as if it’s there and get T3 and T4 to be made
does hyperthyroidism have negative feedback?
no
there’s negative feedback if TSH and TRH are there but neither of them is what’s causing the increase in T3/T4; it’s the antibody that’s boning to the receptor and acting as an agonist
can T3/T4 do negative feedback?
no they can’t do negative feedback on the immune system
what is happening physiologically if you have hyperthyroidism?
very high levels of T3 and T4 because the antibody is causing it to be produced, not the pathway
TSH and TRH levels are dropped - they aren’t what’s causing the high levels of T3/T4 since TSH receptors in the follicular cells are being activated by the antibody
do people with hyperthyroidism get goiters?
very because the antibody is overstimulating the follicular cells so you end of with a goiter
what are symptoms of hyperthyroidism?
1) heat intolerance: individuals have very high metabolism so they’re producing lots of heat – compared to hypothyroidism that gets very cold
2) decreased weight: due to burning glucose and high metabolism
3) increased sympathetic response: helped by T3 and T4 so you get jumpy
where is the adrenal gland located?
it sits on top of the kidney
what’s the composition of the adrenal gland?
1) cerebral cortex
2) medulla: sympathetic ganglion
what endocrines are secreted by the adrenal gland?
corticosteroids (steroids)
what impacts do the endocrines of the adrenal gland have?
metabolic saving processes
it tries to keep us from starving
what does cortisol do? where is it secreted from?
it’s secreted by the adrenal gland
1) stress endocrine
2) acts on the liver
3) increases breakdown of fat components
4) acts on epinephrine and norepinephrine
5) anti-inflamatory
how does cortisol act as a stress endocrine?
having enough energy and food was a big problem and the job of adrenal gland endocrines is to impact the metabolic saving processes to keep us from starving
cortisol comes into play to make sure that we can shut down the things we don’t need as much to make sure we have enough glucose for later
makes sure we’re alive tomorrow
how does cortisol act on the liver?
cortisol mainly acts not he liver
it increases catabolism (breakdown) of glucose so that we can do our equation 2 to get energy available
how does cortisol increase breakdown of fat components?
this is why stress sometimes costs weight loss since fat storage are being broken down
then cortisol starts breaking down proteins which means muscle loss
then after it will eventually break down bone because we don’t need any of those stores if we aren’t going to be alive tomorrow
how does cortisol act on epinephrine and norepinephrine?
it acts on epinephrine and norephinephrine to impact blood pressure
they are sympathetic NTs which makes sense because we’re stressed out
sympathetic system gives you high blood pressure so you can move nutrients out to the muscles where they’re needed
how does cortisol act as an anti-inflammatory?
inflammation is our immune system
so cortisol works against immune system to reduce it because we’re trying to save energy and one of the ways to accomplish that is to lower things that we don’t need
what are the costs of cortisol?
1) cortisol decreases growth
if you don’t have enough energy to make small you function, why would you want to get bigger if you can’t support it?
2) cortisol reduces reproduction
don’t take girls to scary movies because they induce stress which means high cortisol which means reduced reproductive interest
do humans need cortisol?
yes
when there’s no cortisol, you’re dead within days
when you drop below a certain cortisol threshold, you’re in extreme danger; you need some cortisol going through the system
what are the two types of adrenal gland disorders?
1) adrenal insufficiency
2) hypercortisolism
what is adrenal insufficiency disorder? what’s another name for it?
it’s a type of hypothyroidism because you have low cortisol levels but cortisol is still there; you’re just not producing enough to be in the safe range
“Addison’s syndrome”
what are symptoms of adrenal insufficiency disorder?
individual will be weak – you need cortisol to impact liver to get glucose put into the system so without cortisol the glucose levels drop too low and you can’t run equation 2 as efficiently
without enough cortisol you’ll have low BP because of low epinephrine and norepinephrine levels
what is hypercortisolism? what’s another name for it?
too much cortisol in the system
this doesn’t mean the person is under stress all the time – this is someone who is Hawaii relaxing on a beach yet their cortisol levels are still high; it’s an unnatural response
“Cushing’s syndrome”
what are physiological symptoms of hypercortisolism?
1) individuals will have high glucose levels because liver is being impacted by cortisol
high glucose levels people usually get diagnosed as being diabetic when they actually just have hypercortisolism
2) individuals usually have high BP
3) shut down of immune system so immune response is lowered/suppressed by cortisol
4) fragile bones because you’re breaking down fats, proteins then bone
5) distinct obesity pattern
what obesity pattern is associated with hypercortisolism?
you might say this doesn’t make sense since they’re putting so much energy in the system they should be losing weight…
but if you put high levels of cortisol in and keeping it in the system
cortisol wants to make sure you don’t starve so if you have all this extra energy in the system, the cortisol requires what isn’t used and putting it back into fat resources you can use later just incase you don’t get to eat tomorrow
the fat gets repositioned around organs so you see lots of belly fat and around your neck because you have vital organs in your belly and your brain in your head
what is somatic growth?
involves adding cells to you via mitosis
NOT adding reproductive cells via meiosis
what is needed for somatic growth?
1) increase protein synthesis
2) increase glucose catabolism
3) increase adipose catabolism
4) increase bone growth at epiphyseal plates
how does protein synthesis impact somatic growth ?
you have to increase potion synthesis
making proteins costs us energy
why is glucose needed for somatic growth?
need to increase glucose catabolism
running our equation 2 to get ATP which are needed for protein synthesis process
why is fat needed for somatic growth?
you need to increase adipose catabolism
need to break into fat storage
where do bones growth?
bones only grow at the epiphyseal plates near the ends of the bone
you don’t grow from the middle of your bone
you don’t see adults get taller, they just get more massive, because the plates gets fused
the steroids associated with puberty is what causes the plates to fuse which stopes upwards growth by changing bones and not allowing them to increase in length
this dow not mean growth is stopping because you can grow towards in weight gain
why does somatic growth need increased bone growth at the epiphyseal plates?
you can add all these cells being made to the bones at the epiphyseal plates
if you damage one of the plates in a kid, you need to get it checked out because you could have damaged the plate and they could end up with growth deficits
what endocrines controls somatic growth?
1) growth hormone
2) T3/T4
3) insulin
4) sex endocrines
5) cortisol
when are GH levels highest? specifically during a life time and throughout the day
highest during development
not consistently high though because you have growth spurts
it’s an endocrine that’s most active at night, not during the day which makes sense because GH needs a lot of energy and at night you can devote all your energy to it
what role does GH play in somatic growth?
it’s an endocrine 2 so it stimulates the release of IFG-1 –> release of IGF-1 happens in liver and bones because IGF-1 increases mitosis and gets us to make more cells
GH is an endocrine 2 that’s unusual in the it can stimulate muscle development all on its own
it mobilizeds nutrients and gets glucose into the system and breaks down fats so that we have energy available = fatty acid and glucose levels rise
what role does IGF-1 play in somatic growth?
release of IGF-1 is stimulated by GH
release of IGF-1 happens in liver and bones
IGF-1 increases mitosis and gets us to make more cells
bones need their own source of IGF-1 to make sure they grow and so they don’t have to rely on an incoming IGF-1
what role does T3/T4 play in somatic growth?
they impact growth by allowing for GH impact on the bones
if you have a problem with the thyroid gland you get a kid who doesn’t reach their maximum height
how does insulin impact somatic growth?
it increases protein synthesis
possibly IGF-1 agonist – still being researched
how do sex endocrines impact somatic growth?
testosterone and estrogen promote outward growth, not upward
how does cortisol impact somatic growth?
it inhibits GH secretion and effects
how is calcium regulated?
it’s NOT run through the hypothalamus so it does NOT have a quartet
is calcium static?
calcium is not static in the bones
we just saw in terms of cortisol that if we raise cortisol levels too much we break into the bones for energy and release Ca which is why bones are dynamic and not static
if you put stress on your bones they’ll grow but if you don’t then they get weaker and take longer to heal
what are the different forms of calcium in the body?
99% crystalline in our bones
- 9% intracellular calcium usually found in our soft tissues like muscle (SR)
- 1% extracellular calcium
where is extracellular calcium found?
0.1% of the calcium in our body is extracellular calcium
of that, 1/2 is restricted to plasma so it’s bound and is a static barrier
the other 1/2 is free to move and can be exchanged between plasma and intracellular fluid into the intracellular fluid
this is the part that we can play around with and measure with our blood levels
can impact dietary intake to impact GI track to uptake more calcium or via urinary extraction so that there isn’t as much loss of calcium (kidneys)
what is hypocalcemia?
having too low of calcium in the portion of calcium that is free to be moved and exchanged throughout the body
what regulates calcium?
1) PTH
2) 1,25-dihydroxyvitamin D
where does PTH come from?
it’s secreted by the parathyroid gland which sits on the thyroid gland
removing the thyroid gland makes calcium levels drop
how does parathyroid hormone impact calcium regulation?
1) PTH increases bone reabsorption to make sure you have enough calcium by breaking down bone so bone density goes down
2) PTH also impacts kidneys so that there’s decreased urinary excretion
3) PTH also increases dietary uptake indirectly by impacting another endocrine called 1,25-dihydroxyvitamin D
what is another name for 1,25-dihydroxyvitamin D?
calcitriol or active D
what is the source of 1,25-dihydroxyvitamin D?
UV impact on skin creates vitamin D
how is 1,25-dihydroxyvitamin D made?
a vitamin D precursor gets converted by liver then kidney into 1,25 ONLY under the influence of PTH
what does 1,25-dihydroxyvitamin D do?
it stimulates intestines to absorb calcium
1,25 causes GI tract to add transporters to allow for uptake of calcium
without 1,25 you can ingest as much calcium as you want but without 1,25 then it’ll just go right out of you in your urine
typically require synthetic intake in the US because we stay inside more and even when we go outside we put on lots of sunscreen to prevent UV from going through
what is rickets?
not having enough calcium and your bones actually bend
this is what’s happening with people’s legs when they’re bow legged
why do we need the circulatory system?
need circulatory system to create convective flow
diffusion needs help because it has a problem with distance which is significant enough to the point that diffusion is only effective over 2 millimeter lengths
what is convective flow?
convective flow is taking some sort of medium and being able to move it so we have conventive flow of air via our lungs
what are the components of the circulatory system?
1) Pump = heart: needed to fight gravity
2) containment = vessels (vasculature)
3) medium = blood
what is the flow of blood through the heart?
1) pulmonary veins (O)
2) L atrium
3) L ventricle via bicuspid
4) aorta via semilunar valve
5) body (O to deO)
6) suferior/inferior vena cava
7) R atrium
8) R ventricle via tricuspid
9) pulmonary artery via SLV
10) lungs (deO to O)
what do pulmonary beings do?
they bring stuff back from the lungs
aka bring back oxygenated blood
what does the bicuspid valve do?
it’s a one way valve between the atrium and ventricle so that blood flow doesn’t go backwards
what does the semilunar valve do?
it ensures that blood doesn’t go back into the left ventricle
what is the interventricular septum?
The interventricular septum (IVS) is the wall separating the the ventricles of the heart from one another
which chambers of the heart are bigger?
atria are smaller than ventricles
right side of the heart is smaller than the left
why the atria are smaller than the ventricles and why the right side of the heart is smaller than the left?
The left side is larger because it sends oxygenated blood throughout the whole body. The right side is smaller because it sends the blood through the lungs to be oxygenated
The ventricles on the left hand side of the heart have to pump blood all around the body. so require thick muscular walls.
atria are smaller than ventricles because blood is pumped out of the heart at greater pressure from these chambers compared to the atria.
is the myocardium striated?
striated muscle
nice parallel arrangement, not radial arrangement like in our smooth so the connect of our thins is via z discs/z lines, not dense bodies
what controls the myocardium?
autonomic control like smooth muscle
not somatic control
what is the structure of the myocardium?
short and branched myofibers
not very long myofibers like in our skeletal muscles
they aren’t long because we fused cells together to create our long skeletal muscles because we needed tension to be created to move the whole distance
in our heart we need a 3D contraction so we don’t need one cell wrapped around, we need multiple smaller ones that work together to create 3D squeeze
how are the myocardial cells connected?
all the cells are connected via intercalated discs
neighboring cells pull on each other when they contract; they don’t rip apart
intercalated discs are junctions between two myofibers
what junctions are in the myocardial cells?
desmosome and gap junction in the intercalated disc between two myofibers
our tight junctions aren’t present because they prevent extracellular movement which we need in our heart
how do desmosomes play a roll in the myocardium?
they are the strongest connection between cells so they’re good in our heart
that’s why when one cell contracts, it doesn’t rip apart from its neighbor
how do gap junctions play a roll in the myocardium? what are its pros and cons?
they act as our electrical synapses
they are bidirectional (cost)
an action potential can move along one cell and be passed immediately over to the other
the benefit to electrical junction is speed so all the cells can contract at the same time = synchronization so your heart squeezes at the same time
what triggers a contraction in the myocardium?
calcium induced calcium release
you start with an AP on the PM into traverse tubules (only NT trigger our AP)
voltage gated calcium channels in our transverse tubules: as AP comes along, we can trigger the threshold that gets these Ca channels to open
inside our TTs is interstitial fluid so when channels open, extracellular Ca comes into the cytosol of myocardial cell
what are the steps of a myocardial contraction?
1) AP on PM into traverse tubules
2) voltage gated calcium channels in our transverse tubules open and extracellular calcium comes into the cytosol of myocardial cell
3) ECF calcium floods into the cytosol and binds to troponin which changes the shape of tropomyosin and moves it out of the way so that myosin can bind to actin and get CBC started
4) ECF calcium also binds to chemically gated channels on the SR and triggers release of Ca from SR
what is calcium induced calcium release?
cardiac muscle has a pool of calcium requested inside of it in the SR
the SR has chemically gated calcium channels and the ligand that binds to them is calcium!
so some of the calcium that comes into the cytosol from the ECF binds to troponin but the rest binds to chemically gated calcium channels in the SR to cause them to open and released SR Ca into the cytosol
we have two sources of Ca in our cardiac muscle!
the Ca from the SR can either bind to troponin or it can bind to other chemically gated channels in the SR to trigger more release of Ca
the Ca brought in from the ECF starts the release of the requested Ca in the SR
why do we need CBC?
to get us tension
what kind of tension is there in our myocardial cells?
it’s a build up
cardiac needs to squeeze a space so that fluid exits
when tube of toothpaste is brand new, you don’t have to squeeze hard to get toothpaste out but at the end you’re squeezing super hard and need to increase the amount of force to get more and more fluid out
we aren’t creating linear tension, we’re creating a 3D tension so we get a ramping up of tension rather than a quick build up like in skeletal muscles
how does myocardial relaxation happen?
• Remove cytosolic calcium and return it to SR anddd out to extracellular
if you only pump it to one place, our system won’t work after a while
if you only pump to SR then you don’t have any extracellular calcium to start the process
this is why you need tight junctions!
why does your heart need tight junctions?
you need extracellular calcium to start calcium induced calcium release
this is why you don’t want tight junctions because you need calcium to be able to move easily
it’s a serious heart condition when there isn’t appropriate calcium levels outside of your heart
what causes the pattern of cardiac contraction?
we get a distinctive, always consistent flow pattern – this only happens if contraction pattern happens in the right way
all the cells of the heart don’t contract at exactly of the same time
the pattern of electrical flow creates the pattern of contraction
all of the AP are coming from CNS – we have efferent autonomic signals
what is the senatorial node?
70 bmp
it’s in the right atrium
it starts the action potential in the tissues associated with the heart
the AP from the CNS gets passed on to atrial cells surrounding the senatorial node
the AP will get the atrial cell to contract and transmit the AP to its neighboring cell via gap junctions in the intercalated discs
what separates our atria from our ventricles?
a white layer of fats and lipids
electrical activity is prevented in lipids = myelin so it prevents interaction between atria and ventricles so that the AP must go to atrioventrical node which is at the top of the inter ventricular septum
what is the atrioventrical node?
it’s at the top of the interventricular septum and transmits AP from atria to ventricles
what are the bundles of His?
they go through interventricular septem and carries electrical activity from atria to the bottom of the ventricle without passing AP to any of the ventricular cells within the interventricular septem = conduction without contraction
they releases AP through purkinje fibers (PF) – now the ventricular cells will contract and transmit to neighboring cells
what kind of contraction happens due to the bundles of his?
they bundles of his release AP through the purkinje fibers so that the ventriclular cells contract and transmit to neighboring cells
contraction for the ventricles is bottom to top because bundles of his get the conduction to the bottom
what are the parts of an EKG?
1) P wave
2) QRS complex
3) T wave
what is the P wave of an EKG?
atrial depolarization
atrial cells are doing their contraction, doing their depolarization
this is not the same as the AP graph where the y axis is the Vm of the cell, it’s the potential - this is the squeeze of the atrial part of the heart
what is the QRS complex of an EKG?
ventricular depolarization
squeezing of the ventricle which is a lot bigger because there’s more tissue in the ventricles
what is the T wave of an EKG?
ventricular repolarization
the electrical activity associated with the relaxation of the ventricle
what part is missing in an EKG? why?
Relaxing the atria
you’re not missing it, it’s just overtaken by the QRS complex because they happen at the same time
