Renal - Hormonal Regulation of Body Fluid - Lecture 6 Flashcards
What is the responsible for the major elimination of water?
What are 4 other ways that water loss can be facilitated?
Kidneys! - regulate water balance and are the major route for elimination of water from the body
- Insensible water loss - evaporation from cells of the skin & respiration
- Sweat
- GI tract via fecal water (100mL/day)
- Diarrhea - increased dramatic water loss (20L/day)
State the order of magnitude of water loss for the following:
Urine, Insensible, feces, sweat
Urine > Insensible (skin/respiration) > Feces > Sweat
1500 mL > 700 ml > 200 mL > 100 mL
What is the TBW (total body water) amount?
What is ICF?
ECF?
42 L
ICF = 28L
ECF = 14L ( Plasma: 3.5L and Interstitial: 10.5 L)
Which selective permeabilities are similar?
P, ICF, ISF, ECF
P and ECF, ISF and ICF
What is the osmolarity in each fluid compartment?
300 mosm/L
What is the major electrolyte composition of the following:
- Plasma
- Interstitial Fluid
- Intracellular fluid
- Plasma - Na & Cl-
- Interstitial Fluid - Na + and Cl-
- Intracellular Fluid (skeletal muscle) - K+
Describe:
- Positive Water Balance
- Negative Water Balance
- Intake Exceeds Loss
2. Intake is Less than Loss
What is the major determinant of plasma osmolality? (or body fluid osmolality)
Na+
What kind of urine does high water intake produce?
Low intake/Loss of Water?
- Hypoosmotic Urine
2. Hyperosmotic Urine
Where is ADH stored? How is it released?
- ADH is stored in the posterior Pituitary
2. It is released via exocytosis when the nerve endings are stimulated
What kind of feedback system does ADH utilize?
What kind of Physiologic regulation does it perform?
Where are the sensors located?
What is the effector?
What is the target of ADH?
What is the response of ADH
- Negative feedback
- Osmolality regulation of plasma, volume & pressure of the vascular system
- Effector - EXOCYTOSIS of ADH from terminal axons of supraoptic neurons & paraventricular neurons into the blood of the posterior pituitary
- The target is Extracellular ADH receptors in distal tubules & collecting duct
- Response: change in cytoarchitecture and cellular matrix remodeling, increased passive water reabsorption into RENAL MEDULLA
Which of the 5 factors that inhibit/stimulate ADH release?
- Nicotine
- Angiotensin II
- ANP
- Ethanol
- Nicotine - stimulates ADH release (water reabsorption increases)
- Angotensin II - stimulates ADH release (water reabsorption increases)
- ANP - inhibits ADH release (reduce ECFV)
- Ethanol - inhibit ADH release (producing large amounts of urine due to decreased water reabsorption)
Where are afferent fibers from the Baroreceptors carried?
CN 9 and 10
- leads to posterior pituitary of hypothalamus
What is ADH most sensitive to? (3)
What is the ADH release threshold? (in mosm/kgH20)
What is the thirst threshold?
- High sensitivity to increases and decreases in plasma osmolality
& DECREASES in BP or VOLUME! - ADH threshold is near 280 most/kgH20
- Thirst threshold - 298 mOsm/kgH20
What are some ADH disorders?
- Central (pituitary) diabetes insipidus - Polyuria, polydipsia
- Nephrogenic Diabetes Insipidus - Polyuria, Polydipsia
What is polyuria? Polydipsia?
Polyuria - copious amounts of dilute urine
Polydipsia - excessive thirst