Physiology and Membrane Structure Quiz
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Questions and Answers

What is the study of biological function?

Physiology

What is the emphasis in the study of physiology?

Mechanisms

The study of physiology only involves human bodies.

False

What is the application of knowledge of human physiology in the management of dysfunctions and diseases in human beings?

<p>Medical physiology</p> Signup and view all the answers

What is the key subject in medicine?

<p>Physiology</p> Signup and view all the answers

What is the basis of understanding disease processes and the insight into disease management and prevention?

<p>Physiology</p> Signup and view all the answers

The Nobel Prize in Physiology and Medicine is awarded for groundbreaking discoveries in the health sector.

<p>True</p> Signup and view all the answers

What is the foundation of medical practice?

<p>Physiology</p> Signup and view all the answers

What did S. Singer and G. Nicolson propose in 1972?

<p>The fluid mosaic model</p> Signup and view all the answers

What percentage of the molecules in the membrane are lipids?

<p>98%</p> Signup and view all the answers

What percentage of the lipids are phospholipids?

<p>75%</p> Signup and view all the answers

Fatty acids can only contain an even number of carbon atoms.

<p>False</p> Signup and view all the answers

What are fatty acid chains that contain no double bonds called?

<p>Saturated</p> Signup and view all the answers

What are fatty acid chains that contain one or more double bonds called?

<p>Unsaturated</p> Signup and view all the answers

Glycolipids are molecules that contain only carbohydrate.

<p>False</p> Signup and view all the answers

What are glycolipids that are attached to the amino alcohol sphingosine called?

<p>Glycosphingolipids</p> Signup and view all the answers

Glycosphingolipids are found in greatest amounts in muscle tissue.

<p>False</p> Signup and view all the answers

Glycosphingolipids are antigenic.

<p>True</p> Signup and view all the answers

Glycosphingolipids are only found in human cells.

<p>False</p> Signup and view all the answers

The carbohydrate portion of a glycolipid serves as a cell surface receptor for cholera and tetanus toxins.

<p>True</p> Signup and view all the answers

What are prostaglandins, thromboxanes, and leukotrienes collectively known as?

<p>Eicosanoids</p> Signup and view all the answers

Eicosanoids are produced in large amounts in specialized glands.

<p>False</p> Signup and view all the answers

What is phosphatidylinositol cleaved into?

<p>Diacylglycerol and inositol trisphosphate</p> Signup and view all the answers

Diacylglycerol and inositol trisphosphate act as second messengers.

<p>True</p> Signup and view all the answers

Cortisol blocks the action of phospholipase A2.

<p>True</p> Signup and view all the answers

Aspirin blocks the action of cyclooxygenase.

<p>True</p> Signup and view all the answers

NSAIDs block the action of leukotriene biosynthesis.

<p>False</p> Signup and view all the answers

Cholesterol molecules constitute about 20% of the membrane lipids.

<p>True</p> Signup and view all the answers

Cholesterol stiffens the membrane.

<p>True</p> Signup and view all the answers

Steroid hormones are derived from cholesterol in animals.

<p>True</p> Signup and view all the answers

Hormones like testosterone and estradiol are involved in the development of sexual characteristics.

<p>True</p> Signup and view all the answers

Proteins constitute about 75% of the membrane weight.

<p>False</p> Signup and view all the answers

What are proteins that pass through the membrane called?

<p>Integral (transmembrane) proteins</p> Signup and view all the answers

Most integral proteins are glycoproteins.

<p>True</p> Signup and view all the answers

Peripheral proteins do not protrude into the phospholipid layer.

<p>True</p> Signup and view all the answers

What is an example of a peripheral protein that is bound to the spectrin network?

<p>The anion exchanger</p> Signup and view all the answers

What is the protein that anchors the anion exchanger to the spectrin network?

<p>Ankyrin</p> Signup and view all the answers

What is the predominant protein of the skeletal protein lattice?

<p>Spectrin</p> Signup and view all the answers

What is the name for chemical signals that cells use to communicate?

<p>Receptors</p> Signup and view all the answers

All signaling molecules can enter the target cell.

<p>False</p> Signup and view all the answers

Second messenger systems are triggered by the binding of a messenger to a surface receptor.

<p>True</p> Signup and view all the answers

Proteins can function as enzymes.

<p>True</p> Signup and view all the answers

Channel proteins are always open.

<p>False</p> Signup and view all the answers

What are the three types of stimuli that channel protein gates respond to?

<p>Ligand-regulated gates, voltage-regulated gates, and mechanically regulated gates</p> Signup and view all the answers

Pumps actively transport ions across the membrane.

<p>True</p> Signup and view all the answers

Carriers transport substances against their concentration gradients.

<p>False</p> Signup and view all the answers

Membrane structure makes them selective about which molecules can pass through them.

<p>True</p> Signup and view all the answers

The hydrophobic interior of the lipid bilayer makes membranes impermeable to polar molecules.

<p>True</p> Signup and view all the answers

What are the two basic processes of transport through the cell membrane?

<p>Diffusion and active transport</p> Signup and view all the answers

Lipid solubility is a factor that determines how rapidly a substance diffuses through the lipid bilayer.

<p>True</p> Signup and view all the answers

The term permeable means that a structure allows the passage of substances through it; impermeable means that a structure doesn't allow the passage of substances.

<p>True</p> Signup and view all the answers

Plasma membranes permit all substances to pass through them at the same rate.

<p>False</p> Signup and view all the answers

The lipid bilayer portion of the membrane is permeable to polar molecules like glucose.

<p>False</p> Signup and view all the answers

Simple diffusion is the only form of transport across cell membranes that is not carrier-mediated.

<p>True</p> Signup and view all the answers

Simple diffusion requires metabolic energy.

<p>False</p> Signup and view all the answers

Facilitated diffusion occurs down an electrochemical gradient.

<p>True</p> Signup and view all the answers

Facilitated diffusion requires metabolic energy.

<p>False</p> Signup and view all the answers

Facilitated diffusion uses a membrane carrier and exhibits all the characteristics of carrier-mediated transport.

<p>True</p> Signup and view all the answers

Simple diffusion is a type of carrier-mediated transport.

<p>False</p> Signup and view all the answers

Mediated transport is much more rapid than other molecules of similar molecular weight and lipid solubility.

<p>True</p> Signup and view all the answers

The transport rate of mediated transport is not affected by the concentration of the transported compound.

<p>False</p> Signup and view all the answers

Active transport requires energy.

<p>True</p> Signup and view all the answers

Passive transport requires energy.

<p>False</p> Signup and view all the answers

Primary active transport uses ATP.

<p>True</p> Signup and view all the answers

Secondary active transport uses ATP directly.

<p>False</p> Signup and view all the answers

Active transport allows the concentration of substrates against concentration or electrochemical potential gradients.

<p>True</p> Signup and view all the answers

Active transport moves solutes down an electrochemical potential gradient.

<p>False</p> Signup and view all the answers

The Na+-K+ ATPase pump moves 3 sodium ions out of the cell and 2 potassium ions into the cell.

<p>True</p> Signup and view all the answers

The Na+-K+ pump maintains a high intracellular concentration of sodium ions.

<p>False</p> Signup and view all the answers

Secondary active transport relies on the electrochemical gradient created by primary active transport.

<p>True</p> Signup and view all the answers

Cotransport occurs when two solutes move in opposite directions across the membrane.

<p>False</p> Signup and view all the answers

Countertransport occurs when two solutes move in the same direction across the membrane.

<p>False</p> Signup and view all the answers

Cardiac glycosides inhibit the Na+-K+ pump.

<p>True</p> Signup and view all the answers

Osmosis is the flow of water across a semipermeable membrane from an area of high solute concentration to an area of low solute concentration.

<p>False</p> Signup and view all the answers

A semipermeable membrane allows the passage of both water and solutes.

<p>False</p> Signup and view all the answers

The presence of solute decreases the chemical potential of water.

<p>True</p> Signup and view all the answers

A solution with a higher solute concentration has a higher chemical potential of water.

<p>False</p> Signup and view all the answers

Decreasing the chemical potential of water in a solution lowers vapor pressure, lowers the freezing point, and lowers the boiling point.

<p>False</p> Signup and view all the answers

Osmolarity refers to the total solute concentration of a solution.

<p>True</p> Signup and view all the answers

A 1 milliosmolar solution contains 1000 milliosmoles of solute particles per liter.

<p>False</p> Signup and view all the answers

The normal osmolarity of intracellular and extracellular fluid is approximately 300 mOsm.

<p>True</p> Signup and view all the answers

What does the equation $\pi = g \times RT \times C$ represent?

<p>Van't Hoff's law for osmotic pressure</p> Signup and view all the answers

Study Notes

Physiology

  • Physiology is the study of biological function, focusing on how the body works from the cellular level to the organismal level.
  • The emphasis is on mechanisms and cause-and-effect sequences.
  • It examines how living organisms function.
  • Human physiology specifically studies the functions of cells, organs, and organ systems in the human body.
  • Medical physiology applies human physiology knowledge to manage dysfunctions and diseases in human beings.

Membrane Structure

  • In 1972, S. Singer and G. Nicolson revised the fluid mosaic model of membrane structure.
  • The model suggests that globular proteins are embedded in the lipid bilayer with nonpolar segments interacting with the interior portion of the bilayer and polar portions protruding from the membrane surface.
  • Membrane lipids are predominantly phospholipids.
  • They form a bi-layer with hydrophilic phosphate-containing heads facing the water and hydrophobic tails facing the center of the membrane.
  • Fatty acids are monocarboxylic acids that usually contain an even number of carbon atoms.

Glycolipids

  • Glycolipids are molecules containing both carbohydrate and lipid components.
  • Like phospholipids, they are essential components of all membranes, but are concentrated in nerve tissue.
  • They are found in the outer leaflet of the plasma membrane and play a role in cellular interactions, growth, and development.
  • Glycolipids are antigenic and serve as a source of blood group antigens, embryonic antigens, and some tumor antigens.
  • Prostaglandins, thromboxanes, and leukotrienes are collectively known as eicosanoids.
  • They originate from polyunsaturated fatty acids with 20 carbons.
  • Prostaglandins are potent compounds affecting both physiological and pathological responses, acting locally.
  • They are produced in small amounts in various tissues rather than specialized glands.

Membrane Lipids

  • Lipids are about 98% of membrane molecules, 75% of which are phospholipids.
  • Amphiphilic molecules arrange into a bilayer.
  • Hydrophilic phosphate heads face water. Hydrophobic tails avoid water and face the center of the membrane.

Cholesterol

  • Cholesterol molecules found among fatty acid tails constitute about 20% of membrane lipids.
  • Cholesterol interacts with phospholipids, making the membrane less fluid in spots.
  • High concentrations conversely increase fluidity.

Membrane Proteins

  • Proteins are only about 2% of membrane molecules by weight—however, they represent about 50% by mass and are larger than membrane lipids.
  • Some proteins, called integral proteins, pass entirely through the membrane.
  • Other proteins, called peripheral proteins, do not protrude into the lipid bilayer but adhere to the face of the membrane.
  • Many integral proteins are glycoproteins with oligosaccharides on the outer membrane layer.
  • Functions include receptors, second messenger systems, and enzymes.

Channel Proteins

  • Channel proteins are integral proteins with pores allowing water and hydrophilic molecules to pass through.
  • These gates respond to various stimuli such as chemical messengers, electrical potential changes, and physical stress (e.g., stretch or pressure)

Transport of Substances Through the Cell Membrane

  • Membranes are selective about what passes through.
  • The lipid bilayer is impermeable to polar molecules.
  • Transport can be through diffusion or active transport.
  • Diffusion depends on lipid solubility.

Membrane Permeability

  • Permeability refers to a structure allowing substance passage.
  • Plasma membranes exhibit selective permeability, allowing some substances to pass more easily than others.
  • The lipid bilayer is permeable to nonpolar, uncharged molecules.
  • It is impermeable to ions and large, uncharged polar molecules.
  • It's slightly permeable to small, uncharged polar molecules like water and urea.

Simple Diffusion

  • Occurs down an electrochemical gradient.
  • Does not require metabolic energy.
  • Flux (flow) depends on concentration gradient, partition coefficient, diffusion coefficient, membrane thickness, and surface area.

Facilitated Diffusion

  • Like simple diffusion, it occurs down an electrochemical gradient.
  • However, it employs a membrane carrier protein exhibiting saturation and competition.

Active Transport

  • Moves substances against electrochemical gradients.
  • Requires metabolic energy—typically ATP.
  • Primary active transport directly uses ATP, and secondary active transport leverages energy from primary active transport electrochemical gradients.

Osmosis

  • Osmosis is the movement of water across a semipermeable membrane from a lower solute concentration to a higher solute concentration.
  • Osmosis occurs because solute concentration gradients alter the chemical potential of water, affecting osmosis.

Osmolarity

  • Osmolarity is a measure of the total solute particle concentration.
  • The normal osmolarity of intracellular and extracellular fluid is approximately 300 mOsm.

Calculating Osmotic Pressure

  • Van't Hoff's law calculates osmotic pressure.
  • Variables include concentration (C), gas constant (R), absolute temperature (T), and the number/factor of particles (g)

Vesicular Transport

  • Large particles, fluids, or molecules move through vesicles.
  • Endocytosis brings matter into a cell.
  • Exocytosis releases matter from a cell.
  • Endocytosis types include phagocytosis, pinocytosis, and receptor-mediated endocytosis.

Tonicity

  • A hypotonic solution has a lower solute concentration than the interior of a cell, causing water to flow into the cell, potentially bursting it (hemolysis).
  • A hypertonic solution has a higher solute concentration than the interior of a cell, causing water to flow out of the cell, potentially shrinking it (crenation).
  • An isotonic solution has an equal solute concentration, resulting in no net water movement.

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Transport of Substances Through the Cell Membrane Lecture PDF

Description

Test your knowledge on the fundamentals of physiology, focusing on cellular and organism functions. This quiz also covers the fluid mosaic model of membrane structure and the role of phospholipids. Perfect for students studying human physiology and cellular biology.

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