Cell Biology: Vesicular Transport Quiz
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Questions and Answers

What is the process by which large, water-soluble molecules are transported across the cell membrane?

  • Facilitated Diffusion
  • Simple Diffusion
  • Vesicular Transport (correct)
  • Passive Diffusion

Which of the following best describes phagocytosis?

  • Transport of substances across the membrane by carriers
  • Active transport of ions through channels
  • Engulfment of solid particles by the cell (correct)
  • Engulfment of liquid particles by the cell

What is the osmotic pressure?

  • The pressure that facilitates osmosis
  • The pressure required to stop osmosis (correct)
  • The pressure exerted by solute particles in a solution
  • The pressure created by water movement

Which condition is necessary for both exocytosis and endocytosis to occur?

<p>Presence of $Ca^{2+}$ and energy (A)</p> Signup and view all the answers

What characterizes pinocytosis?

<p>It is characterized by the engulfment of liquid solutions. (B)</p> Signup and view all the answers

How does the Gibbs Donnan effect influence ion distribution?

<p>It leads to unequal distribution of ions due to impermeable solutes. (B)</p> Signup and view all the answers

What happens to the total surface area of the cell as a result of exocytosis and endocytosis coupling?

<p>It remains constant. (D)</p> Signup and view all the answers

What defines osmosis in terms of solute concentration?

<p>Movement of water from high to low water concentration. (B)</p> Signup and view all the answers

What is the process by which water moves from low solute concentration to high solute concentration?

<p>Osmosis (B)</p> Signup and view all the answers

What does osmotic pressure measure in a solution?

<p>The pressure required to stop osmosis (A)</p> Signup and view all the answers

What unit is used to express the osmotic concentration of a solution?

<p>Osmole (B)</p> Signup and view all the answers

How many osmoles are produced when 1 gram of a substance that dissociates into two ions is dissolved?

<p>2 osmoles (D)</p> Signup and view all the answers

What is the standard osmolarity of extracellular and intracellular fluids in the body?

<p>290 milliosmoles per liter (D)</p> Signup and view all the answers

What is the relationship between osmolarity and osmolality in biological fluids?

<p>Osmolarity is measured in osmoles per liter and osmolality in osmoles per kilogram (C)</p> Signup and view all the answers

What is the effective osmotic pressure produced by plasma proteins known as?

<p>Colloidal osmotic pressure (B)</p> Signup and view all the answers

What pressure corresponds to a concentration of 1 milliosmole per liter at normal body temperature?

<p>19.3 mm Hg (D)</p> Signup and view all the answers

What determines the filtration coefficient of a membrane?

<p>Surface area and permeability of the membrane (A)</p> Signup and view all the answers

Which process primarily facilitates the movement of water through membranes in the body?

<p>Osmosis (B)</p> Signup and view all the answers

What is solvent drag in the context of ultrafiltration?

<p>The movement of solute molecules due to water flow (A)</p> Signup and view all the answers

How does water normally move across the plasma membrane?

<p>Primarily through aquaporins and to some extent by simple diffusion (A)</p> Signup and view all the answers

Which statement about plasma osmolarity is true?

<p>Normal plasma osmolarity is approximately 290 osmol/L (C)</p> Signup and view all the answers

What is the effect of increased blood glucose on plasma osmolarity?

<p>Increases plasma osmolarity (B)</p> Signup and view all the answers

Which type of solution has a greater osmolality than plasma?

<p>Hypertonic solution (B)</p> Signup and view all the answers

What happens to cell volume when osmolality of the extracellular fluid (ECF) increases?

<p>Cells shrink (A)</p> Signup and view all the answers

What is the primary role of the Na+-K+ pump in relation to plasma osmolarity?

<p>Keeps low sodium levels inside the cell (A)</p> Signup and view all the answers

Why is saline (0.9 % NaCl solution) used in medical treatments?

<p>It expands plasma volume without affecting cells (B)</p> Signup and view all the answers

What is one effect of the Gibbs-Donnan effect on ion distribution?

<p>Greater negativity inside the cell compared to ECF (A)</p> Signup and view all the answers

How does the presence of non-diffusible plasma proteins in blood affect water distribution?

<p>It facilitates reabsorption of water from interstitial fluid to blood (C)</p> Signup and view all the answers

What is the relationship between osmolarity of ECF and ICF under normal conditions?

<p>ECF and ICF have equal osmolarity (A)</p> Signup and view all the answers

What primarily drives the process of filtration across capillary walls?

<p>Hydrostatic pressure (D)</p> Signup and view all the answers

Which force is a filtering force in the Starling forces concept?

<p>Capillary hydrostatic pressure (Pc) (B)</p> Signup and view all the answers

What effect does a positive net filtration pressure (NFP) have?

<p>Fluid loss from the blood (D)</p> Signup and view all the answers

Which of the following is NOT a factor affecting filtration?

<p>Surface tension of the fluid (B)</p> Signup and view all the answers

Which force tends to cause osmotic movement of fluid into the capillaries?

<p>Capillary plasma colloid osmotic pressure (Пр) (C)</p> Signup and view all the answers

What happens when filtering forces exceed reabsorbing forces?

<p>Fluid is filtered into interstitial spaces (C)</p> Signup and view all the answers

What is the role of interstitial fluid colloid osmotic pressure (Πif)?

<p>To facilitate fluid movement into the interstitial spaces (C)</p> Signup and view all the answers

When calculating net filtration pressure, what does a negative result indicate?

<p>Fluid is absorbed back into the capillaries (B)</p> Signup and view all the answers

Flashcards

Vesicular Transport

The process of moving large water-soluble molecules across the cell membrane, using vesicles.

Exocytosis

A type of vesicular transport where materials are released from the cell via vesicles fusing with the membrane.

Endocytosis

A type of vesicular transport where materials are taken into the cell via vesicles forming from the membrane.

Phagocytosis

A type of endocytosis where large particles, like bacteria, are engulfed by the cell.

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Pinocytosis

A type of endocytosis where small particles or liquids are taken into the cell via vesicles.

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Osmosis

The passive movement of water across a semipermeable membrane from a high water concentration to a low water concentration.

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Osmotic Pressure

The pressure required to stop the movement of water across a semipermeable membrane due to osmosis.

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Exocytosis/Endocytosis

Coupled processes that maintain cellular membrane area by balancing the addition of membrane material during exocytosis with the removal during endocytosis.

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Plasma Osmolarity

A measure of the total concentration of dissolved solutes in blood plasma, calculated using the concentrations of sodium, glucose, and blood urea nitrogen (BUN).

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Hyperglycemia & Osmolarity

Increased blood glucose levels, like in diabetes, raise plasma osmolarity, drawing water from cells and potentially causing dehydration.

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Renal Failure & Osmolarity

Elevated BUN levels, due to impaired kidney function, also increase plasma osmolarity, leading to fluid shifts.

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Tonicity

A comparison of the osmolality of a solution to that of plasma.

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Isotonic Solution

Has the same osmolality as plasma. Doesn't cause fluid shifts.

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Hypertonic Solution

Has a higher osmolality than plasma. Draws water out of cells.

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Hypotonic solution

Has a lower osmolality than plasma. Pushes water into cells.

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Gibbs-Donnan Effect

The unequal distribution of ions across a cell membrane due to the presence of non-diffusible ions (like proteins) in the cell.

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Filtration Rate

The rate at which fluid is filtered from blood across a membrane, determined by the Net Filtration Pressure (NFP) and the Filtration Coefficient (surface area and permeability of the membrane).

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Ultrafiltration

A type of filtration using a semipermeable membrane that separates large molecules (colloids) from smaller molecules (crystalloids). This is how the kidneys filter blood.

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Solvent Drag

The movement of dissolved molecules (solute) along with the bulk flow of solvent (water) across a membrane due to pressure differences.

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Aquaporins

Specialized protein channels in cell membranes that allow water to pass through quickly and efficiently.

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Filtration vs. Osmosis

Filtration is driven by pressure differences, moving water and dissolved molecules across a membrane. Osmosis is driven by concentration differences, moving only water across a membrane.

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Filtration

Movement of water and solutes through a porous membrane from high to low pressure, driven by hydrostatic pressure.

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Hydrostatic Pressure

The pressure exerted by a fluid against a surface, like the capillary wall, due to its weight.

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Starling Forces

Four pressures that determine fluid movement across capillary walls: capillary hydrostatic pressure (Pc), interstitial fluid hydrostatic pressure (Pif), capillary plasma colloid osmotic pressure (Πр), and interstitial fluid colloid osmotic pressure (Πif).

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Net Filtration Pressure (NFP)

The difference between the filtering forces (Pc and Πif) and reabsorbing forces (Πр and Pif), determining whether fluid moves out of or into the capillaries.

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Factors Affecting Filtration

Factors influencing the rate of filtration: pressure gradient across the membrane, surface area of the membrane, and permeability of the membrane.

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Capillary Hydrostatic Pressure (Pc)

Pressure exerted by blood inside the capillaries, pushing fluid OUT into the interstitial space.

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Interstitial Fluid Colloid Osmotic Pressure (Πif)

Pressure exerted by proteins in the interstitial fluid, pulling fluid OUT of the capillaries.

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Osmotic Concentration

A measure of the number of osmotically active particles (molecules or ions) in a solution per unit volume.

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Osmolality vs. Osmolarity

Osmolality measures the number of osmoles per kilogram of solvent, while osmolarity measures the number of osmoles per liter of solution.

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What is an Osmole?

A unit used to express the osmotic concentration of a solution, based on the number of osmotically active particles.

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What is the relationship between Osmolality and Osmotic Pressure?

Higher osmolality creates a greater osmotic pressure. This means a higher concentration of solute particles will exert a stronger force to draw water towards itself.

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What is Colloidal Osmotic Pressure?

The osmotic pressure produced by plasma proteins, which are large molecules that cannot easily cross the blood vessel walls, contributing to a significant force keeping fluids within the blood vessels.

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Why are ions more osmotically active?

Ions are charged particles that dissociate in solution, effectively increasing the number of osmotically active particles. This results in a stronger osmotic pressure.

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What is the normal osmolality of body fluids?

About 290 milliosmoles per liter for both the extracellular and intracellular fluids.

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Study Notes

Vesicular Transport

  • Vesicular transport is how large, water-soluble molecules move between the extracellular fluid (ECF) and intracellular fluid (ICF) when they cannot be transported by channels or carriers.

Exocytosis

  • Vesicles containing material for export (like secretory granules, hormones, or neurotransmitters produced in the Golgi apparatus) fuse with the cell membrane
  • The fusion area breaks down, releasing the vesicle's contents outside the cell while leaving the cell membrane intact.

Endocytosis

  • This is the reverse of exocytosis, bringing material into the cell.
  • Types include phagocytosis and pinocytosis.

Phagocytosis

  • The process by which cells (like white blood cells) engulf bacteria, dead cells, other bits of microscopic material, or debris.
  • The material contacts the cell membrane, which invaginates, pinches off, creating a membrane-enclosed vacuole with the engulfed material inside, leaving the cell membrane intact.

Pinocytosis

  • This process is similar to phagocytosis but engulfs substances in solution.
  • Vesicles are much smaller.

Noteworthy Points (N.B.)

  • Both exocytosis and endocytosis require calcium ions (Ca2+) and energy.
  • Exocytosis increases the amount of membrane surrounding the cell, while endocytosis removes membrane. This balance maintains the cell's normal surface area.

Osmosis

  • Osmosis is the passive movement of water through a semipermeable membrane from an area of higher water concentration to an area of lower water concentration.
  • Water moves from an area of low solute concentration to an area of high solute concentration across a membrane impermeable to the solute. This is net diffusion of water down its concentration gradient.

Osmotic Pressure

  • Osmotic pressure is the pressure required to stop osmosis.
  • It's a measure of the driving force of osmosis.

Osmolarity & Osmoles

  • Osmolarity is the number of osmotically active particles (molecules or ions) per liter of solution.
  • A solute dissociating into ions (like NaCl or CaCl2) has a greater osmotic effect compared to a non-dissociating solute (like glucose).
  • One osmole is 1 gram molecular weight of an osmotically active solute.
  • 1 milliosmole = 1/1000 osmole
  • 180 grams of glucose = 1 osmole
  • 58.5 grams of sodium chloride = 2 osmoles

Osmolality

  • Osmolality is the number of osmoles of solute per kilogram of solvent.
  • Osmolarity and osmolality are used to measure the concentration of solutes in body fluids, and are typically expressed as osmoles/liter.

Normal Osmolarity

  • Normal osmolality of extracellular and intracellular fluids is about 290 milliosmoles per liter.
  • This is dependent on body temperature and relevant to osmotic pressure.
  • A concentration of 1 milliosmole per liter at 37°C causes 19.3 mm Hg osmotic pressure.

Calculation of Plasma Osmolarity

  • A formula exists to calculate plasma osmolarity: Osmolarity (mOsm/L) = 2 [Na+] (mEq/L) + 0.055 [Glucose] (mg/dL) + 0.36 [BUN] (mg/dL)

  • Increased blood glucose (hyperglycemia) and increased BUN (in renal failure) increase plasma osmolarity.

Tonicity

  • Tonicity describes the osmolality of a solution relative to plasma. Solutions are classified in to:
    • Isotonic: the same osmolality as plasma
    • Hypertonic: a greater osmolality than plasma
    • Hypotonic: a lower osmolality than plasma

Gibbs-Donnan Effect

  • The presence of a non-diffusible ion on one side of a membrane affects the distribution of other diffusible ions in a predictable way.
  • Proteins are non-diffusible anions inside cells; because of this, there are higher levels of osmotically active molecules in intracellular fluid than extracellular fluid.
  • There is more negative charge within the intracellular fluid. There are also differences in electric gradients.
  • Presence of plasma proteins inside the blood ensures the flow of diffusible water from interstitial fluid (ISF) to blood—essential for preventing loss of plasma water in ISF.

Filtration

  • Filtration is the movement of water and solutes through a porous membrane due to hydrostatic pressure, from a high-pressure area to a low-pressure area.

  • It is important for exchange in capillaries.

  • Hydrostatic pressure in capillaries forces fluid and dissolved substances through pores into the interstitial spaces.

  • Conversely, osmotic pressure caused by plasma proteins draws fluid back into the capillaries. This balance prevents significant fluid loss from the blood to the interstitial spaces.

  • Factors affecting filtration include: -Pressure gradient -Surface area of the membrane, -Permeability of the membrane

Ultrafiltration

  • A specific type of filtration, such as that occurring in the glomeruli of the kidneys. where colloid solutions are separated from crystalloids.
  • Solvent drag is involved in this process.

Movement of Water Across Membranes

  • Water moves across membranes by both osmosis and through channels.
  • Water permeates phospholipid bilayers in slow, as it is polar.
  • Aquaporins are water channels that speed up passage of water.

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Vesicular Transport, Osmosis and Filtration Lecture 4 PDF

Description

Test your knowledge on vesicular transport mechanisms, including exocytosis and endocytosis. This quiz covers key processes such as phagocytosis and pinocytosis. Understand how substances move in and out of cells and the role of vesicles in cellular function.

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