What stimulates Angiotensin II secretion
Angiotensin I availability (which is dependent on Renin)
What are the direct effects of Angiotensin II
- *Systemic vasoconstriction (strongest constrictor)
- *increase Na+ reabsorption and H+ excretion in prox. tubules (acts on kidneys via its self and by activating aldosterone)
- *Increase aldosterone secretion (on adrenal gland)
- vasoconstriction –> decreases GFR
- Increase ADH secretion
What are the indirect effects of Angiotensin II
- increase water reabsorption (increase blood volume)
- increase in Na+ reabsorption
- increase BP
- increase thirst (via CNS)
- Metabolic alkalosis
What stimulates aldosterone secretion
- *angiotensin II
- *Hyperkalemia (high potassium)
- *decrease plasma [Na+]
- ACTH (weakest influence)
What are the direct effects of aldosterone
- increase Na+ reabsorption in distal tubules and therefore the passive reabsorption of water
- increase K+ secretion in distal tubules
- increase H+ secretion in distal tubules
What are the indirect effects of aldosterone
- Increase water reabsorption
- increase BP
- decrease serum K+
- Metabolic alkalosis
What stimulates ADH secretion
- increased serum osmolarity (ECF)
- decreased BP/volume
- Angiotensin II
- hypoglycemia
What are the direct effects of ADH
- *Systemic vasoconstriction
- *Insertion of aquaporin channels in distal tubules and collecting ducts leading to increased FREE WATER REABSORPTION
- increase ACTH secretion
What are the indirect effects of ADH
- decrease serum Na+, which decreases serum osmolarity
- increase BP
- decreases urine output
What hormones stimulate reabsorption of Na+ in the kidneys
Angiotensin II and aldosterone
How is water reabsorption stimulated in the kidneys
indirectly stimulated by Angiotensin II and aldosterone
and directly by ADH
how is potassium reabsorption stimulated in the kidneys
indirectly stimulated by Angiotensin II and aldosterone
When levels of coritsol are elevated, how does it behave
like aldosterone
What prevents reabsorption of K+ in the kidneys
aldosterone
What drives K+ from ECF to ICF
- insulin
- catacholamines (epiniphrine)
What are the major overall effects of Angiotensin II
- increase BP
- increase blood volume
What are the major overall effects of aldosterone
- increase BP
- increase blood volume
- decrease serum [K+]
What are the major overall effects of ADH
- increase BP
- increase blood volume
- decrease [Na+]***
What stimulates renin secretion
- decrease in BP (renal perfusion pressure)
- decrease in [NaCl] around macula densa
- increase efferent SNS activity
- *Independent of one another
What is the rate limiting step in the mechanism of activating angiotensin II
the release of renin
*this is very tightly controlled
What is the job of renin
to hydrolyze angiotensinogen into angiotensin I
What inhibits renin
- increase in BP
- lots of Angiotensin II (which ultimatly increases BP)
- ANP (atrial natriuretic peptide)
- *independent of one another
When [NaCl] is low around the macula densa what is happening?
- Renin release will be stimulated
- the [ECF] will decrease
How is Kenny’s SNS affecting his RAA axis?
Kennys hypovolemia and increased HR stimulates increase SNS activity, which increases renin release
How does angiotensin II vasoconstrict?
promotes increase in intracellular [Ca2+] through actions of phospholipase C and IP3
Angiotensin II effects on the CNS
- increases sympathetic NS outflow
- increase BP
- increase cardiac output - dipsogenic actions (stimulates thirst)
- Increase ADH release
- increase ACTH
What stimulates thirts
- increase in plasma osmolarity (ECF)
- decrease blood volume
- decrease blood pressure
- increase in angiotensin II
- dryness of mouth
Angiotensin II effects on the kidneys
- decreases GFR due to vasoconstriction
- promotes Na+ reabsorption in the prox. convoluted tubule
- inhibits renin secretion
What is another name for vasopressin
ADH
At max. plasma ADH what will happen to urine production?
Volume of urine produced will be very low (low urinary flow rate) but the osmolarity of the urine produced will be very high
**Therefore, ADH is directed at water not solute!
What is our estimated plasma volume?
~ 3 liters
How does ADH increase water reabsorption in the distal tubules and collecting ducts?
By binding to its receptor and activating aquaporins which allow water to be reabsorbed
Normal physiological pH
- 4 +/- 0.02
* Baby’s don’t have as much control over this as adults
bronsted lowry acid
Can donate a proton
Bronsted lowery base
can accept a proton
lewis acid
can accept a pair of electrons
lewis base
can donate an electron pair
strong acid/base behavior and example
complete dissociation occurs (one way arrow with the reaction formula)
ex. HCL —> H+ + Cl- (get two molecules total)
what is the pH of a solution if you add 0.2 moles of HCl to 3 L of water?
pH= 1.17
how to get from pH to [H+]
pH= -log[H+]
What is the relationship between pKa and Ka
inverse relationship (the bigger the Ka the smaller the pKa)
[A-] is the conjugate ____ and [HA] is the conjuate _____
base and acid
What does it mean when the ratio of weak acids is high?
it is forced to dissociate
Ka and Keq are fixed for what conditions
temperature and pressure
when the ratio of conjugate base/conjugate acid is one, what does that mean about the pKa and pH
pKa= pH
is the conjugate acid or base in higher concentration when the pH > pKa and why
the base is in higher concentration becasue the conjugate acid is being forced to dissociate into its conjugate base
In what ratio will the forms of carbonic acid exist in the ECF? pKa of carbonic acid= 3.77
[HCo3-]/[H2Co3] = 4265.79
hint. HH eqn
buffer region
from pKa -1
to
pKa +1
(buffer region spans +/- 1 pKa unit from when pKa=pH
does the acid or base predominate when the pH
acid form predominates
coordinates of a titration curve
Y axis: pH
x axis: mol OH-
each buffer region or platue will occur when pKa=pH
Explain the buffer zone and what happens as it reaches the equivalence points
when you add conjugate base (with a salt) to a weak acid in a buffer system, you continue to add base until all of the acid form us used up and you only have the new base left. Once it is all used you are at the equivalence point. (you have completely removed your proton)
when you get to pKa=pH you have removed half of the protons from the acid and put them on half of the bases
formula for phosphoric acid
H3PO4
formula of carbonic acid
H2CO3
formula for acetic acid
CH3COOH
does concentration of the buffer have any effect on the pH it works at?
no, but the concentration of the buffer DOES effect the buffer capacity at which is can resist pH change
a normal range for lab data is
the mean value +/- 2 SD (includes 95.4% of population) anything outside of 4 SD is defintely abnormal
accurate
close to the true value
precise
little variation
factors that effect a value besides disease
gender, age, position, blood source, time of day, nutritional status, genetics, pregnancy, medications, stress, environment, ethnicity
draw table formate for sensitivty, specificty, etc.
**
sensitivity
measures the ability of a test to dect disease in a diseased population
**positivity in the disease
(top row)
**Looking to avoid false negatives
specificity
measures the ability of a test to dect non-disease in a non-diseased population
**detecting negativity in health
(last row)
**Looking to avoid false positives
false positive
you test positive for a disease you DO NOT have
false negative
you test negative for a disease you actually DO have
high sensitivity, low specificity will result in
more false positives
low sensitivity, high specificity will result in
more false negatives
+ predictive value
the true number of positive results in all positive results
what is the relationship between the predictive value + and disease prevalence?
the PV + will be higher in diseases that are more prevalent
- as disease prevalence increases, PV + is equally huge, and PV- decreases
Is there more fluid in the ICF or ECF?
ICF
compartments of the ECF
- plasma
- interstital fluid
- lymphatics
- transcellular water
* plasma and interstital fluid is separated by the plasma membrane
TBW is a function of what
LBM - our weight is about 60% water (less for F)
mass (kg) x 0.6 = TBW
More adipose means what for TBW
more fat = less TBW
is ECF or ICF more constant over time
ICF
how much does ECF and ICF contribute to TBW
20%- ECF
40%- ICF
what indicator do you use when measuring TBW
3H20
what indictor do you use when measuring ECF Volume
14C/inulin (bc doesn’t get into cells)
what indicator do you use when measuring plasma volume
125I (remains in vasculature)
assumptions when calculating fluid volumes with indicatiors
- indicator dispersed uniformly and only within the compartment of interest
- volume of indicator added was negliable to the total volume of the compartment
- enough time was allowed for equilibrium to be achieved
- the compound added was not metabolized, excreted, or secreted
ECF =
ECF = Plasma volume + TCW + ISFV
total blood volume =
total blood volume = plasma volume /(1-Hct)
anion gap =
[sum of Cations (+)] - [sum of anions (-)]
in bulk solution, anions and cations are __
equal
normal range for an anion gap
12-18mEq/L
what cations and anions are more prevalent in the ECF
Na+, Cl-, HCO3-, glucose
what cations and anions are more prevelent in the ICF
PO4-, K+, Mg2+