30 Questions
How can interstitial fluid volume be measured?
By calculating extracellular fluid volume minus plasma volume
What is the ionic composition of plasma and interstitial fluid?
Plasma has a higher concentration of proteins
What is the relationship between solute concentration and water concentration in a solution?
Higher solute concentration means lower water concentration
What is the ionic basis of the resting membrane potential in neurons?
Sodium channels are closed and potassium channels are open
Which of the following is not a characteristic of the resting membrane potential in neurons?
There is a net movement of ions across the membrane
What is the relationship between blood volume and hematocrit?
Blood volume is directly proportional to hematocrit
What peptide hormone induces thirst, salt appetite, and Blood Pressure elevations in the brain?
Angiotensin II
Which transmembrane protein is encoded by the family of slc9 genes?
SLC9A4
What is the role of Relaxin-3 in water drinking behavior?
Involved in water drinking behavior during pregnancy and/or other conditions
Which hormone is responsible for regulating water homeostasis throughout the body?
Secretin
What is the physiological stimulus for the increase of Angiotensin II in body fluids?
Hypovolemia, dehydration, and Na deficiency
How is Ang II-dependent water intake controlled according to Noda et.al., 2022?
Through GABAergic neurons
What is the driving force for water intake?
Thirst mechanism
What stimulates the hypothalamic thirst center osmoreceptors?
Plasma osmolality of 2-3%
Which factor may lead to hyponatremia?
Overuse of diuretics
What inhibitory feedback signals can suppress thirst?
Relief of dry mouth
Where are the thirst-driving systems located in the brain?
Subfornical organ and organum vasculosum of the lamina terminalis
Which neural pathways originate thirst signals from the SFO and OVLT?
AT1a neurons
What is the primary mechanism involved in causing edema?
Increased capillary hydrostatic pressure
Which brain region is the main sensing site for increases in sodium concentration that induce thirst?
Organum vasculosum of the lamina terminalis (OVLT)
Which conditions are prone to causing intracellular swelling?
Depression of tissue metabolic systems
Which neuronal population in the subfornical organ (SFO) is activated to suppress thirst during water drinking?
Cholecystokinin (CCK) neurons
What is a prelude to the death of tissue in an ischemic leg?
Intracellular edema
What causes sodium and other ions to diffuse into the interior of cells during inflammation?
Increased cell membrane permeability
Which neuronal population in the median preoptic nucleus (MnPO) is activated to suppress thirst during water drinking?
Glucagon-like peptide-1 receptor (GLP1R) neurons
In which fluid compartment does edema mainly occur?
Extracellular fluid compartment
Which brain region receives signals from the oral cavity and/or gastrointestinal tract during water drinking?
Nucleus of the solitary tract (NTS)
Which neuronal populations in the parabrachial nucleus (PBN) are activated to suppress thirst during water drinking?
Oxytocin receptor (Oxtr) neurons and prodynorphin (PDYN) neurons
What is the initial step recommended in deciding on proper therapy?
Determining primary loss or gain of sodium
Which brain region is involved in sensing systemic dehydration for water intake control?
Both B and C
Test your knowledge on calculating interstitial fluid volume and understanding the ionic basis of the resting membrane potential in neurons. Learn about the relationship between extracellular fluid volume, plasma volume, and blood volume, as well as the permeability of potassium and sodium channels in resting conditions.
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