Lecture 3 Flashcards
Fluid Intake Methods (3)
Metabolism - 10%
Food - 30%
Beverages - 60%
Fluid Excretion Methods (4)
Feces - 4%
Sweat - 8%
Insensible Loss (Skin/Lungs) - 28%
Urine - 60%
Triggers of Thirst (3)
- Osmolarity
- Volumetric
- Angiotensin
Osmolarity
Increased osmolarity from increased salt intake or decreased water volume triggers thirst response to try and fix the osmolarity of the blood.
Volumetric
Decreased blood volume. Limited vascular restriction assistance. Need to increase intake and volume to offset the imbalance.
Receptors to Detect Volumetric Imbalance
- Low Pressure - baroreceptors in great veins, pulmonary vessels, and right atrium
- High Pressure - baroreceptors in carotid sinus & aorta
Angiotensin II Effects (5)
- Thirst
- More Water/Na+ absorption
- Releases aldosterone
- Vasoconstriction
- ADH Secretion
ADH Mechanism
Released by hypothalamus. Causes blood vessels to constrict and makes the collecting duct highly permeable to water to allow for lots of its reabsorption (doesn’t affect salt). Increases blood pressure and volume
Aldosterone Mechanism
Acts on Na+/K+ pumps and increases their numbers in the kidneys. Pulls more sodium out of cell and increases amount of sodium in blood stream that causes water to follow it.
Other ways to Intake Fluids (3)
- IV
- Gastric Tubes
- Subcutaneously
Body Fluid Compartments (3)
- Vascular - blood vessels
- Interstitial - in between vessels and cells
- Intracellular - inside cells
Fluid Forces (3)
- Hydrostatic pressure - pushes fluid from inside the vessel out, decreases in pressure the farther away from the heart you get
- Osmotic pressure - pushes fluid from outside the vessel in, constant throughout the body
(net out closer to the heart, net in farther away) - Osmosis - driven by osmolarity, water moves towards hypertonic solutions
Types of Fluid Imbalances (2)
- Extracellular fluid
2. Body fluid concentrations
Extracellular Imbalances (aka Saline Imbalances)
Impacts vascular and interstitial fluid volumes. Caused by too little or too much fluid. Concentration is right, just not the right volume.
How do extracellular imbalances occur? (too little volume) (5)
- Loss of salt water from the body (vomiting, diarrhea)
- Excess renal excretion of salt & water (excess use of diuretics or aldosterone deficiency)
- Hemorrhaging
- Excessive sweating (diaphoresis)
- Burns
Thiazide Mechanism
Block Na+/Cl- transporter in distal tubule, preventing Na+ absorption, decreasing blood volume due to Na+ and H2O excretion
Potassium-Sparing Diuretic Types
- Sodium Channel Inhibitors
2. Mineral Corticoid receptor antagonist
Sodium Channel Inhibitors Mechanism
Block sodium channels in collecting duct, decreases Na+ reabsorption and subsequent excretion of potassium. Water follows the Na+
Mineral Corticoid Receptor Antagonist Mechanism
Competes with aldosterone receptor, decreases sodium reabsorption of sodium channels