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faridi homeostasis
122 final
43
Pharmacology
Graduate
04/07/2010

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Cards

Term
amt of water in avg person
Definition
40 L
Term
water daily intake
Definition

2500

2300: food and drink

200: cell metabolism

Term
water daily output
Definition

2500

kidneys: 1500 mL > primary regulator of water excretion at the hormonally controlled late DCT and collecting duct

skin: 600 mL > sweat, evaporation

lungs: 300 mL > evaporation

GI tract: 300 mL > vomiting, diarrhea

Term
fluid homeostasis
Definition

hypervolemia: increase water and solutes > infusion of isotonic solution

hypovolemia: decrease water and solutes > trauma, blood loss, hemorrhage, surgery, burns, vomiting, diarrhea

 

overhydration: increase too much water > drinking too much

dehydration: decrease too much water > sweating (sweat is primarily water, some solutes)

Term
shock
Definition

must lose more than 15 mg/kg of blood

 

-can be hemorrhagic or trauma caused

Term
4 regulations of fluid homeostasis
Definition

1. ADH

2. aldosterone

3. thirst center

4. SNS

Term
ADH
Definition

binds to ADH receptor on principal cells of late DCT and collecting duct > GPCR > activates adenylate cyclase to make cAMP > activates PKA > cell signaling causes increased aquaporins > allow for water reabsorption

 

stimulus for release: osmoreceptors detecting high osmolality

-produced in the supraoptic nuclei of the hypothalamus, released through the posterior pituitary

Term
thirst
Definition

regulates water intake

 

-stimulus:

1. dry mouth: stimulates thirst center in the hypothalamus

2. hypothalamic osmoreceptors: detects increased osmolality > stimulates thirst center

3. decreased blood pressure: detected by baroreceptors > baroreceptor reflex > production of angiotensin 2 > stimulates thirst center

Term
aldosterone
Definition

stimulus

1. increased Na and decreased K concentration in plasma

2. low BP > renin angiotensin system > angiotensin 2

 

-aldosterone released from the adrenal cortex > places extra Na/K antiporters on the principal cells of the late DCT and collecting duct > Na reabsorption and K secretion

Term
SNS
Definition

low BP in renal blood vessels > baroreceptors in heart, aortic arch, carotid arteries activated > send signal to medulla > increased sympathetic outflow causes:

1. increased renin from JG cells

2. vasoconstriction of systemic arterioles (except afferent arteriole because it is protected by NO)

 

-intense SNS stimulation causes extreme vasoconstriction > vasoconstrict afferent arteriole > decreased GFR > less fluid loss > increased BP/BV 

Term
electrolyte homeostasis
Definition

enter: food and beverage

leave: kidneys, skin, feces, severe vomiting that involves intestines, diarrhea

 

electrolyte = salt that dissociates in water

Term
 Na levels
Definition

136-145 meq/L NORMAL

> 145 meq/L HYPERNATREMIA

< 136 meq/L HYPONATREMIA

Term
potassium levels
Definition

3.5-5.1 meq/L NORMAL

> 5.1 meq/L HYPERKALEMIA

< 3.5 meq/L HYPOKALEMIA

Term
Ca levels
Definition
9-11 mg/dL NORMAL
Term
causes for edema
Definition

edema = accumulation of fluid in the interstitium

 

1. decreased plasma colloid osmotic pressure (Po): liver disease

-albumins located in plasma pull blood from interstitium

2. increased hydrostatic pressure (PHb): hypertension

3. increased capillary permeability: local inflammation or injury

-fluid is able to flow out of capillaries easier

4. lymphatic obstruction/removal

-water usually leaves via the lymph

Term
water disturbances
Definition

1. HYPERVOLEMIA: gain both water and solutes: infusion of isotonic fluid

2. HYPOVOLEMIA: loss of both water and solutes: blood loss, hemorrhage, trauma, burns, vomiting, diarrhea

3. OVERHYDRATION: gain water

-drinking too much water

4. DEHYDRATION: loss of water

-sweating (more water than solute loss)

Term
Na homeostasis
Definition

roles of sodium

1. muscle contraction

2. nerve impulse

3. major extracellular positive ion

4. primary regulator of water movement in the body

-cotransports glucose and AA in the late DCT and collecting duct

 

Term
hypernatremia
Definition

associated with hypertonicity > water loss

1. sweating

2. excessive salt intake

 

results: cell shrinkage, increased thirst (high osmolarity), increased blood volume and pressure

 

clinical presentation

1. thirst

2. restlessness

3. irritability

4. spasticity

5. seizures

6. coma

7. death

8. intracranial bleeding

9. edema

Term
classifications of hypernatremia
Definition

1. hypervolemic hypernatremia: iatrogenic (caused my medication mistakes)

2. hypovolemia hypernatremia

3. isovolemic hypernatremia: diabetes insipidus (no ADH > water loss)

Term
hyponatremia
Definition

result: cell swelling, nervous impulse conduction, muscle contraction

 

clinical presentation

for hypovolemic hyponatremia: poor skin turgor, tachycardia, hypotension

1. cellular swelling:cerebral edema with increased intracranial pressure

2. lethargy

3. confusion

4. seizures

5. coma

 

Term
classifications of hyponatremia
Definition

depending on serum osmolality

 

1. hypertonic hyponatremia: hypertonic infusions

2. hypotonic hyponatremia: classified further

3. isotonic hyponatremia

Term
classifications of hypotonic hyponatremia
Definition

depending on ECF volume

 

1. hypovolemic (low BP, high HR, poor skin turgor) hypotonic hyponatremia

2. hypervolemic hypotonic hyponatremia

3. isovolemic hypotonic hyponatremia: SIADH > too little ADH hormone

Term
K homeostasis
Definition

roles:

1. major intracellular positive ion

2. sets resting membrane potential

3. nerve impulse

4. muscle contraction

5. maintenance of normal cardiac rhythm

6. acid base balance (H/K antiporter on luminal membrane of intercalated cells of late dct and collecting tube)

Term
diuretics and K homeostasis
Definition

loop diuretics: inhibit the Na/K/2Cl symporter on the luminal side of the thick ascending limb of the loop of henle

-causes more salt to stay in the urine > water moves from plasma to the urine > decreased BV > decreased BP

-K wasting > K goes out into the urine > can  cause hypokalemia > need to ingest extra K

Term
hyperkalemia
Definition

caused by

1. excessive K intake: overuse of salt substitutes

2. decreased K excretion: renal failure

3. metabolic acidosis > H/K antiporter on the intercalated cells > high H > H secreted and K reabsorbed

 

results: 

1. muscle weakness: restlessness, neuromuscular irritability, paralysis

2. intestinal problems: cramping and diarrhea

3. cardiac problems: EKG problems

4. death by CARDIAC arrest

Term
hypokalemia
Definition

causes

1. decreased K intake: unbalanced diets

2. increased K secretion: potassium wasting diuretics (loop diuretics)

3. metabolic alkalosis: not enough H > need to reabsorb H and secrete K > using H/K antiporter on the luminal membrane of intercalated cells in the late DCT and collecting tubule

 

results:

1. muscle weakness: decreased tone in smooth muscles

2. intestinal problems

3. cardiac problems: bradycardia

4. death by RESPIRATORY arrest

Term
Ca homeostasis
Definition

roles

1. crucial to normal body function

Term
hypercalcemia
Definition

1. thyroid gland releases calcitonin

2. calcitonin inhibits the actions of osteoclasts which breakdown bone

3. stimulates actions of osteoblasts which cause bone formation which uses Ca and PO4-

 

causes: cancer (lung, breast, multiple myeloma > metastatic > attacks bone which causes bone breakdown> increased Ca > leads to cardiac arrest), hyperthyroidism (too much PTH)

symptoms

1. heart dysrhythmias

2. fatigue

3. confusion

4. nausea

5. coma

6. cardiac arrest

7. calcification of the soft tissues

 

treatment: biphosphonates (bone loss inhibitors) and calcitonin

Term
hypocalcemia
Definition

1. PTH is released from the parathyroid gland

2. PTH causes increased number and action of osteoclasts which break down bone into Ca

3. PTH causes increased Ca and Mg reabsorption at the kidneys

4. causes increased vitamin D at the kidney > vit D is activated to calcitriol > required for Ca and PO4 absorption in the GI tract 

 

causes: vit D deficiency (no calcitriol > cannot reabsorb Ca into GI tract > lose Ca in feces), parathyroid gland dysfunction (no PTH production)

 

symptoms

1. muscle spasms

2. tetanus around mouth and extremities: Ca is needed for NT release

3. ECG changes that lead to heart failure

4. respiratory arrest

Term
acid/base levels
Definition

NORMAL ECF: 7.35-7.45

ACIDEMIA: < 7.35

ALKALEMIA: > 7.45

Term
acid base concepts
Definition

acids = proton donors

bases = proton acceptors

 

pH = log [H+]

 

henderson hasselbalch equation: relates pH to the ratio of the concentrations of the conjugate base and acid

pH = pKa + log [A-]/[HA]

Term
H+ homeostasis
Definition

must be regulated because pH changes cause conformational changes in proteins which change their functions

 

H+ changes caused by

1. metabolism: CO2 as a byproduct which is then used by carbonic anhydrase

2. diet: ingest acids or bases

Term
3 regulations of H+ in the body
Definition

1. chemical

2. respiratory

3. renal

Term
chemical regulation of H+
Definition

-fastest > buffers resist changes in pH and are most effective at their pKa

 

1. phosphate buffer system: intracellular and in urine

-H2PO4- + OH- > HPO42- + H+

-H+ secreted into the urine > cannot leave the body as H+ > converted to H2PO4 and excreted

 

2. protein buffers: bind or release H+

-NH2-X-COOH + H+ > NH3+-X-COOH

-NH2-X-COOH + OH- > NH2-X-COO-

 

3. carbonic acid/bicarbonate buffer system using carbonic anhydrase

CO2 + H2O > H2CO3 > H+ + HCO3-

-most important

Term
respiratory regulation of H+
Definition

chemoreceptors respond to changes in PaCO2, H+ and pH

 

1. hyperventilation > decreased PaCO2 > decreased H+ > increased pH

 

2. Hypoventilation > increased PaCO2 > increased H+ > decreased pH

Term
renal regulation of H+
Definition

slowest form of regulation (hours to days)

 

1. reabsorption of bicarb

2. formation of bicarb by kidney tubule cells

3. secretion of H+ in the PCT and DCT

-intercalated cells: H/K antiporter

-PCT: Na/H antiporter

-H+ is titrated with Na2HPO4 and NH3 to yield excretable acidic products > CANNOT URINATE H+ > will damage ureters

Term
4 types of acid/base disturbance
Definition

1. respiratory acidosis

2. respiratory alkalosis

3. metabolic acidosis

4. metabolic alkalosis

 

Term
metabolic acidosis
Definition

excess acid or loss of bicarb

 

causes of excess acid production:

1. diabetic ketoacidosis

2. starvation acidosis

3. lactic ketosis (lactic acid breakdown)

4. kidney disease (H+ not getting excreted)

5. hyperkalemia (H/K antiporter)

 

causes of loss of bicarb:

1. diarrhea

2. excessive vomiting that involves the intestines

 

compensation

1. increased ventilation: decrease PaCO2 > decrease H+ > increase pH

2. increased excretion of H+ > titrate with NH3 or PO4

Term

respiratory alkalosis

 

Definition

caused by hyperventilation which decreases PaCO2

 

-compensation

1. HCO3- excretion into the urine

 

 

Term
 respiratory acidosis
Definition

caused by hypoventilation which increases PaCO2

 

compensation:

1. kidneys retain bicarb

2. secrete H+ (Na/H antiporter in the PCT, H/K antiporter at the intercalated cells of the late DCT/collecting duct)

Term
metabolic alkalosis
Definition

 

excess bicarb or loss of acid

 

causes of loss of acid:

1. mild to moderate vomiting that only involves the stomach

2. hypokalemia (H/K antiporter)

 

causes of excess base:

1. ingesting too much bicarb

 

compensation

1. decrease ventilation > increase PaCO2 > increase H+ > decrease pH

2. increase bicarb secretion

 

Term
davenport diagram or acid/base nomogram
Definition

1. blood pH > alkalosis vs acidosis

2. PaCO2 level > high PaCO2 = metabolic, low PaCO2 = respiratory

3. plasma HCO3 level >high bicarb = respiratory, low bicarb = metabolic

Term
2 types of intercalated cells
Definition

1. H+ secreting

2. bicarb secreting

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