PSL-Week 4 Flashcards
What ares oem of the improtant functions of Ca, in what is it involved?
involved in intracellular signalling where changing its concentration allow vesicle to be exocytosed, in hormone secretion as in insulin, blood clotting, neral ability, and buliding/ maintanence of the bone
How is Ca found in the extracellular matrix of the bone?
Ca is trapped as it forms crytsals called hydroxyapalite and when it gets ionized, then the Ca is free and can be exchanged
Where can we find Ca and in which of the places is it most abundant
Ca can be found in ECF, extracellular matrix, and intracellular as free Ca
it is most abundunt in the Extracellular matrix of teh bone (99%)
What are the three cells responsible for forming and maintaining the bone?
osteoblast: bone forming cell
osteoclast- bone resoprtion
osteocytes: bone maintenance
What is the turnover for calcium in infants vs adults?
infants-100%
adults- 18%
Osteoclast are responsible for boen resorption, how do they achieve that?
the cells for osteoclasts are usually large as tehy are multinucleated, and they use the proteases and acidic environment to start dissolving the matrix of the matrix of teh bone where the proteases come from the cell and the acidic environement is achieved by HCL where H is provided by carbonic anhydrase and Cl by the HCO3 and CL exchanger
Hiw do osteoblast promote the forming of osteoclasts?
that is through the RANK/ RANKL interaction where RANK is the receptor on inactive osteroclast and RANKL is teh ligand for that receptor which is made by osteoblast, so by osteoblast making RANKL and bindning the receptor, that will cause the precurson osteoclast to differentiate and fuse with others to become active
What are the three hormones controlling the plasmsa Ca levels?
parathyroid hormone, calcitriol, and calcitonin
What prevent the interaction between osteoclast and osteoblast RANK/RANKL?
OPG, osteoprotegin which is a receptor also made by the osteoblast to prevent the differentiation and fusion of the osteoclast
RANK/RANKL?OPG system was discovered in late 1990s, if you were employee of biochemistry company, how might you have used this knowledge to develop drug for treating osteoporsis?
mimic effect of OPG
How does PTH increase Ca levels when it is down?
by acting directly on the bone and kidney:
bone- increase RANK”s production and lowers OPG’s to increase bone resorption and have Ca free from crystal
kidney- by having it reabsorb Ca and go back to bloodstream by increasing calcitriol synthesis and reabsorption of Ca in distial tubule
What are characteristics of the parathyroid hormone?
it is apeptide hormone whose main function is to increase Ca and is released from parathyroid gland
How does the parathyroid gland sense the Ca levels to be able to know if the are down?
using the Ca sensing receptor (CaSR) which is a G protein receptor on the chief cells in the parathyroid gland, as long as Ca is bound to receptor, then levels are okay, but when teh Ca isn’t bound, that will initiate sequence of events in teh cell to increase that Ca level in plasma
What are teh three organs that calcitriol needs to get synthesized and becoem active hormone?
skin to absorb sunlight, the liver, and the kidney
what are the precursores until we can have active calcitriol?
7-dehydrocholestrol is the precursor found in our body which is in teh skin so when it gets hit by sunlight, it becomes cholecalciferol and that precursor goes to teh liver to get converted into 25-hydroxycholecalciferol by enzymes of liver and then in the kideny, it get converted into the active hormone calcitriol(1,25-hydroxycholecalciferol) by PTH
how does calcitriol help with Ca absorption?
Ca cannot be absorbed by the digestion system without the help of calcitriol which causes the synthesis of important enzymes to be able to absorb that Ca
How does calcitriol activate the synthesis of enzymes needed to break and absorb that Ca when it is present in digestion system?
Calcitriol binds Vitamin D nuclear receptor found in nuclear membrane by freely diffusing through memebrane and entering cytosol, then this complex, VDR bound to calcitriol, makes it way into nucleus and heterodimerize with RXR so that thsi complex can bind VDRE in DNA and activate transcription of improtant enzymes for Ca absorption
What happens to the phosphates that are released when hydroxyapolite are broken?
Calclitriol will increase its absorption by intestine and reabsorption by kidney to save it for boen fomration while PTH will increase its release of it since it doesn’t need it
What are the thre ways in which PTH raises plasma Ca?
PTH mobilizes the Ca from bone using osteoclasts via the RANK/RANKL
PTH enhaces renal absorption
PTH enhances teh production of calcitriol which will help with abropetion of Ca
Which statment is false?
a- PTH act directly on osteoclasts to increase Ca reabsorption
b- PTH increase Ca through multiple mechanisms
c- PTH is secreted from 4 glands on thyroid
d- PTH is involved withc alcitriol synthesis
a
How is calicitonin different from the other two hormones?
it is secreted due to increase of Ca in plasam and its role is to tone down the Ca levels
How does calcitonin decraese level of Ca plasma?
by increasing kidney release and decreasing bone resroption
What are the consequences of hypercalcemia vs hypocalcemia?
hypercalcemia will cause person to suffer from constipation, psychic moans, boen pain, kidney stones, and psychatric overtones
hypocalcemia will have person suffering from CATS: convulsions, arrhythmias, tetany, spasms/seizure
How is teh water distributed in our body?
2/3 is in the ICF and 1/3 is in the ECF and of that water in the ECF, 3/4 is in the interistitial fluid and other 1/4 is in the plasma
What are consequences of excessive water loss vs having too much water?
too much water loss= hypotension/shock which is due to less ECF causing decrease in blood pressure and can lead to amke of no urine
having too much water will cuase it to build up in lungs, legs,a dn abdomen making it difficult to breath
What is the nephron responsible for?
exerting waste, regulating blood volume, controls pressure, blood pH,a nd vitamin D via PTH
What is definition for osmolarity?
the concentration of solution expressed as total number of solute aprticles per liter
Is the water permeability of collecting duct an all or non response like AP where it either absorb water or it doesn’t?
no, there is graded effect of vasopressin which allows the body to match the concentration of the urine closely to body’s needs
more vasopressin=more water absorption
Where is vasopressin made and what are its primary functions?
made in the hypothalamus and gets secreted by posterior pituitary
main functions include: increase water reabsoprtion to conserve body water, to keep water balance and will increase blood volume and blood pressure
What are teh stimuli that causes teh hypothalamus to secret its ADH?
the most potent signal is the increase in plasma osmolarity which is detected by osmoreceptores in hypothalamus and can also be stimulated by trhe decrese in blood pressure which is sensed by areia walls of heart and the aortic and carotid arteries
What is the process in where the vasopressin cause teh collecting duct to increase its water reabsoprtion?
vasopressin is a hormone that can freely diffuse across membrane and find its receptor in collecting cell, then it bind receptor to signal cAMP and inititiate signal cascade that translate more aquaporins 2 pores and these pores get inserted into membrane facing nephron and they will start absorbing the water and water will go to the bloodstream to decraese the plasma osmolarity
Dave consumes large size pack of salty potato chips. What would you expect to observe in response?
acquaporines moving to apical membrane
Where is aldosterone made and what are its function?
made in zoma glomerulosa in adrenal cortex and its functions are to reabsorb Na which retaisn water, to secrete K, and to act on distal tubule and collecting duct
What are the two ways in which aldosterone is controlled by negative feedback?
cimple way is by K and osmolarity which is stimulated by increasing K concnetration
complex way is by renin-angiotensin II which is stimulated by blood pressure
What inhibts the synthesis of aldosterone?
high osmolarity of ECF
What does the simple way in which aldosterone cause the increase in Na reasboprtion and increse in K secretion
aldosterone will freely diffuse intp the cell’s cytosol of P cells and bind its receptor in cytosol to form the hormone-receptor complex that cna go into nuclues and start transcribing mRNA that will translate into new channels like Na channels and new pumps like Na/K pump to result in increase in Na absoprtion and increase K secretion
What si another way to cause secretion of aldosteroen in teh kidney along other things in response to low blood pressure?
that is through the Renin-angiotensin aldosterone pathway.
The lungs nd liver contain enzymes that convert teh prucorser into angiotensin II
Liver will produce angiotensinogen and then renin from teh juxtaglkomerular cells will travel through bloodstream to convert angiotensinegen into angiotensin I and angiotensin I gets converted into active angiotenin II by ACE from the lungs
How does the renin-angiotensin elevate a low blood pressure?
that is by acting on adrenal cortex to produce aldosterone, by causing vasoconstriction, and by altering the brain to make u think your thirsty and cause drinking
What are characteristics of angiotensin II?
it increases vasopressin, stimulate thirst, cause vasoconctriction, and increase proximal tube Na retention
Where are the juxtaglomerular cells found?
are positioned in the affecerent artiole to sense blood pressure and stimulate RAAS pathway when it sense decreased blood pressure
What are natruiretic peptides?
peptides that act as hormone and are family of ANP, BNP, and CNP which are secreted by secodnary endocrine glands
How are the ANP and BNP hormones involved in decreasing blood pressure?
ANP are found in atria and neurons while BNP are found in ventricular cells and when they stretch, that is due to increased volume and too much pressure on the heart so they cause decrease in Na and water reabsoprtion, they suppress the renin, aldpsterone, and vasopressin all to lower the blood pressure
How is the adrenal gland divided?
into two different tissues, adrenal medulla whcih is modified sympathetic region, and the adrenal cortex which is steroid factory
What is teh hormone released in adrenal medulla and what is its purpose?
the hormone released in epinephrine and its released by activation of sympathetic nervous system and epinephrine’s role is to mediate rapid stress response
What affect does epinephrine cause on the liver and fat once stimulated?
will increase their production to increase ATP by having glucose released by glucogenolysis and fatty acids released
What affect does the epinephrine have on heart, brain, and respiration?
will increase HR by increasing force of contraction to send blood through systematic circulation quicker, will increse alertness of the brain, and will cuase bronchodilation of teh lungs to bring in more oxygen
How does the epinephrien affect the intestine, skin, kidney, and muscle?
it will cuase muscle relaxation in intestine and ateriole constriction in teh skin, intestine, and kidney to have teh blood flow to areas that needs it more for the flight/fight response, and even in the muscle, there will be ateriole contraction for alpha receptores and ateriole relaxation for teh beta 2 receptores since also some muscles will need that blood more than others
Epipen contain epinephrine, how does that help someone with severe allergy reaction?
Epipen contains epinephrine and that is to stimulate dilation which is important for someone with severe allergy reaction to prevent anaphylatic shock where teh airways constrict, so epipen will cause bronchdilation, vasoconstriction of skin/kidney/intestine and vasodilation of skeletal and cardiac muscle
What are the three regions of adrenal cortex and what hormone is produced in each region?
zona glomerulosa- aldosterone
zona fasciulata- glucocorticoids
zona reticularis- sex hormones
How come different reegions of the adrenal cortex secrete different hormones even though all hormones are made from chortisol?
that’s because each region contain different enzymatic activity which will alter teh choristol in different ways producing three different hormones
What are characteristics of androgens. sex hormones, secreted by adrenal cortex?
they are weak compared to estrogens and testoterone but have greater effect on children as their reproductive systems haven’t developed yet but have no effect in adult men and are believed to be source of estrogen in older women after menopause
Why is cortisol esential for life?
it is the main glucocorticoid and has role in mediating long term stress
What are the two effects of cortisol?
has protective effect and metabolic effect, the protective effct is against hypoglycemia and matbolic effect is by having the following process occur like glucogenesis, breaking of skeletal muscle proteins, enhancing lipolysis, and suppressing amino system
How is cortisol secreted and how is it regulated?
stress and circadian rythm will cause hypothalamus to seccrete CRH which acts on the anterior pituitary gland to secrete ACTH and then ACTH will cause adrenal cortex to secrete cortisol which increase blood glucose and decrease immune system, this can be regulated by negative feedbck from cortisol on ACTH or from cortisol on CRH
How can cortisol be used to suppress immune system’s response?
by inbiting teh inflammatory response for conditions like poison ivy, allergies, asthma, but long term use can cause inhibition of ACTH and strophy of cortisol secreting cells
What are characteristics of addison’s disease?
it is chronic disease due to adrenal insufficiency because of hyposecretion of adrenal steroid hormones and can be caused by destroyed adrenal cortex due to autoimmunity or infection and symptoms include hypotension and hypoglycemia
What is cushing’s syndrome due to and what are its symptoms?
due to excess cortisol which can be due to tumour or cortisol therapy and symptoms include hyperglycemia, muscle protein break down, increased appetite, mood elevation, and build of fat at trunch and face
