Exam 4 Flashcards
Function of parathyroid hormone
Acts on kidneys (renal tubules) to increase reabsorption and decrease excretion of Ca2+
Function of antidiuretic hormone
Aka arginine vasopressin
Released from posterior pituitary gland in response to increase in ECF osmolarity/decreased blood volume (dehydration)
Acts on kidneys to increase water and Na+ reabosorption
What inhibits the secretion of antidiuretic hormone?
Alcohol
Function of renin
Enzyme released by kidneys in response to decreased blood pressure
Cuts small peptide off the end of angiotensinogen
Ultimate result after cascade: decreases excretion of Na+ and water, increases reabsorption, and increases excretion of K+, increase in blood pressure
Function of angiotensinogen
After a peptide is cut off by renin, becomes angiotensin I
Made in liver
Function of angiotensin I
Once it reaches the lungs, it is converted to angiotensin II
Function of angiotensin II
Vasoconstrictor
Causes release of aldosterone from adrenal glands
Causes release of antidiuretic hormone
Function of aldosterone
Hormone
Acts on renal tubules to increase Na+ reabsorption and K+ excretion (water follows Na+)
= increased blood volume = increased blood pressure
Also increases K+ uptake into cells
Roles of Na+ in the body
Maintaining water and electrolyte balance
Aids in nutrient absorption
Neural and muscular function
What cation circulates in blood with 50% of the total being bound to albumin?
Ca+
Symptoms of Na+ deficiency
Vomiting, diarrhea, heavy sweating, muscle cramps, mental apathy, loss of appetite
Symptoms of Na+ toxicity
Edema, hypertension
Functions of Cl-
Maintaining fluid and electrolyte balance HCl production (stomach)
Symptoms of Cl- deficiency
Heavy sweating, diarrhea, vomiting (same as Na+)
Functions of K+
Fluid and electrolyte balance
Nerve and muscle function
Growth
Function of epinephrine
Might be important after exercise to prevent hypokalemia (low blood K+)
Function of insulin
Increases K+ uptake after eating
Symptoms of K+ deficiency
Hypokalemia
Diarrhea, vomiting, severe dehydration
Associated with use of diuretics (like alcohol), steroids, laxatives
Muscle weakness, paralysis, confusion, cardiac arrhythmias
May cause hypertension
Symptoms of K+ toxicity
Hyperkalemia
Occurs with overuse of supplements
Muscle weakness, vomiting, severe heart failure
What are the trace minerals?
Cr, Mn, Fe, Cu, Zn, Mo, Se, I
Which is the ferrous form of iron?
Fe2+
Which is the ferric form of iron?
Fe3+ (THREEsomes make me sICk
Function of hemosiderin?
Storage protein for iron
Mainly used in liver and when there is excess
Marker for toxicity
Which form of iron is in heme?
Ferrous (2+)
What makes up hemoglobin?
4 heme groups + 4 protein subunits
What is the function of myoglobin and where does it act?
Muscles
Releases oxygen for ATP production and muscle contraction
What makes up a heme group?
A protoporphyrin ring (nitrogen containing) with ferrous (2+) iron and oxygen
What is a cytochrome?
Cytochromes are, membrane-bound hemeproteins containing heme groups and are primarily responsible for the generation of ATP via electron transport chain
What does the body do if it does not need iron?
It is not absorbed, and therefore excreted with the sloughing off of intestinal cells
What does the body do if it needs iron?
Ferritin releases iron to ferroportin to be transported out of the mucosal cell, it is oxidised, then taken by trasferrin to blood
What is the function of hepcidin?
Released by liver in response to adequate storage of iron
Decreases the absorption of iron
Pulls ferroportin away from the basolateral membrane
How does iron regulate the expression of genes that are involved in its own metabolism?
When present, a 4Fe-4S complex will bind to IRP1, blocking it from attaching to the IRE on the mRNA that codes for the transferrin receptor and ferritin, and unbound IRP2 protein is targeted for destruction by the proteosome = nuclease digestion of transferrin receptor mRNA, and expression of ferritin
When absent, the complex does not bind to the IRP and then it can bind to the IRE = expression of transferrin receptor protein and not of ferritin
Functions of zinc
VERSATILE
cofactor for metalloenzymes and DNA binding proteins
