Homeostasis

Normal cellular function requires that the intracellular composition be maintained within a __________ range.

narrow

The maintenance of constant volume and composition of the body fluid compartments is termed __________.

homeostasis

In an open system, homeostasis occurs through the process of __________ balance.

steady-state

A state of __________ balance exists when input is greater than output.

positive

When input is less than output, a state of __________ balance exists.

negative

Water makes up approximately __________ of the body’s weight.

60%

The intracellular fluid (ICF) compartment contains approximately __________ of the total body water.

two-thirds

The extracellular fluid (ECF) compartment contains approximately __________ of the total body water.

one-third

The __________ compartment is further subdivided into interstitial fluid and plasma.

extracellular fluid (ECF)

The presence of impermeant molecules results in the __________ effect, leading to the accumulation of permeant molecules/ions.

Gibbs-Donnan

The Na+,K+-ATPase transports __________ Na+ ions out of the cell for every two K+ ions into the cell.

three

The major determinant of the osmolality of the extracellular fluid is __________.

Na+

The __________ junction serves as a pathway for the movement of water, ions, and small molecules across the epithelium.

tight

Epithelial cells demonstrate __________ transport, which allows solutes to move from one side of the cell to the other.

vectorial

The driving forces for fluid movement across the capillary wall are __________ pressure and oncotic pressure.

hydrostatic

An isotonic NaCl solution increases the volume of the extracellular fluid without affecting the __________.

intracellular fluid volume

The intracellular fluid is characterized by a low [Na+] and a __________ [K+].

high

Water movement across epithelia is passive and driven by __________ pressure gradients.

osmotic

The apical surface of epithelial cells can have structures like __________, which increase surface area.

microvilli

Transepithelial transport depends on the orientation of specific membrane transporters in the __________ and basolateral membranes.

apical

In individuals with familial hypomagnesemia, mutations affect the function of __________ in renal epithelial cells.

claudin 16

What is homeostasis in the context of body fluids?

Homeostasis is the maintenance of constant volume and composition of the body fluid compartments.

Which ion predominantly influences the osmolality of extracellular fluid?

Sodium (Na+) is the major determinant of the osmolality of extracellular fluid.

What drives water movement across epithelial cells?

Osmotic pressure gradients drive passive water movement across epithelial cells.

What effect do impermeant molecules have on permeant molecules/ions?

The presence of impermeant molecules leads to the Gibbs-Donnan effect, causing accumulation of permeant molecules/ions.

What structural feature can be found on the apical surface of epithelial cells to enhance absorption?

Microvilli increase the surface area on the apical surface of epithelial cells.

What does transepithelial transport depend on?

Transepithelial transport depends on the orientation of specific membrane transporters in apical and basolateral membranes.

What is the role of tight junctions in epithelial tissues?

Tight junctions prevent the passage of substances between epithelial cells, maintaining selective permeability.

How does hydrostatic pressure affect fluid movement?

Hydrostatic pressure promotes the movement of fluid out of capillaries into the interstitial space.

What is the function of the Na+,K+-ATPase pump?

The Na+,K+-ATPase pump helps maintain the electrochemical gradient by transporting sodium out and potassium into the cell.

Define the term 'interstitial fluid'.

Interstitial fluid is the fluid that occupies the spaces between cells within the extracellular fluid compartment.

What is the significance of potassium (K+) in the intracellular fluid?

Potassium (K+) is crucial for maintaining the resting membrane potential and cellular functions.

How do osmotic pressure gradients influence fluid distribution in the body?

Osmotic pressure gradients determine the movement of water between compartments, affecting fluid balance.

What happens to extracellular fluid volume when a hypertonic solution is administered?

Extracellular fluid volume increases, while intracellular fluid volume decreases due to water moving out of cells.

Explain the principle of vectorial transport in epithelial cells.

Vectorial transport allows solutes to be selectively absorbed on one side and secreted on the other side of epithelial cells.

What effect do changes in oncotic pressure have on fluid movement?

Changes in oncotic pressure influence the reabsorption of fluid from the interstitial space back into the capillaries.

Describe the Gibbs-Donnan effect in regards to cellular fluid balance.

The Gibbs-Donnan effect refers to the distribution of ions and water due to the presence of impermeable solutes, influencing fluid balance in cells.

What is osmolality?

Osmolality is a measure of the concentration of solute particles in a solution.

How is osmolality calculated?

Osmolality is calculated by determining the total number of osmoles of solute per kilogram of solvent.

What role does osmolality play in body fluids?

Osmolality influences fluid distribution and movement between body compartments, impacting hydration status.

What is the normal range for plasma osmolality?

The normal range for plasma osmolality is typically between 275 to 295 mOsm/kg.

How do changes in osmolality affect cell function?

Changes in osmolality can lead to cell swelling or shrinking, affecting cellular functions and overall health.

What is an osmometer?

An osmometer is a device used to measure the osmolality of a solution.

What is hyperosmolality?

Hyperosmolality refers to a condition where the osmolality of a fluid is elevated, often indicating dehydration or solute overload.

What is hypoosmolality?

Hypoosmolality refers to a condition where the osmolality of a fluid is decreased, often indicating overhydration or electrolyte imbalance.

What equation describes the relationship between pressure, volume, and temperature in gases?

The Ideal Gas Law (PV=nRT).

What is the equation for calculating osmolality?

Osmolality = 2[Na+] + [Glucose]/18 + [BUN]/2.8.

How do you calculate the concentration of a solute in a solution?

Concentration = amount of solute/volume of solution.

What equation represents the relationship between flow rate, pressure gradient, and resistance?

Flow rate (Q) = Pressure gradient (ΔP) / Resistance (R).

What is the Nernst equation used for?

The Nernst equation calculates the equilibrium potential for a specific ion across a membrane.

How do you calculate the filtration rate in kidneys?

Glomerular Filtration Rate (GFR) = Kf x (ΔP - Δπ), where Kf is the filtration coefficient.

What is the equation for osmotic pressure?

Osmotic Pressure = iCRT, where i is the van 't Hoff factor, C is the concentration, R is the gas constant, and T is the temperature.

What does the Henderson-Hasselbalch equation relate?

It relates pH, pKa, and the ratio of the concentration of an acid and its dissociated form.