phgy 209- homework 1

body fluids and transport mechanisms

what is the fluid portion of blood?

plasma

example: glucose concentration fluctuates throughout the day so _________ homeostatic mechanisms help maintain the stability in the body.

compensatory

what are the two types of fluid in the body

intracellular and extracellular

what is the study of how an organism functions

physiology

any fluid of the body that is not contained in the cells is called _____ fluid

extracellular

principles of physiology

homeostasis is essential for health survival

the functions of organ systems are coordinated with each other

most physiological functions are controlled by multiple regulatory systems, working in opposition

information flow between cells tissues and organs, allowing for the integration of physiological practices

controlled exchange of materials occurs between compartment and across cellular membrane

dictated by laws of chem and physics

require the transfer and balance of matter and energy

structure is a determinant of function

Which of the following is significantly different between the interstitial fluid compartment and the plasma in nearby capillaries?

Dissolved protein concentration

what is the difference between plasma and interstitial fluid

the protein concentration ( < plasma)

which pair is most similar in composition

interstitial fluid and plasma

proteins must be retained within the ___ and are not required in the __

intracellular

extracellular

homeostatic variables _____

can undergo oscillations around an average value but still be considered to be in balance

When a homeostatic control system activates compensatory mechanisms in response to the deviation of a variable from normal, the mechanism generally ____ the variable to overshoot in the opposite direction of the original change.

does not overcompensate and force

which pair of compartments are the most different in their compositions

intracellular fluid and extracellular fluid

true or false, homeostasis implies that a given physiological function or variable is rigidly constant with respect to time

false

One of the main concepts of physiology states that physiological processes require the transfer and balance of ___ and __

matter and energy

Water is the most abundant ______ in the body.

solvent

Water exists as a liquid at temperatures between what two temperatures

0-100 C

what is true of amphipathic molecules

they contain polar or ionized regions at one site and nonpolar regions at other sites, when they dissolve in water they cluster with the nonpolar regions oriented toward the center of the cluster and polar regions facing the water

Solute concentration is defined as the amount of the solute present in a unit volume of

solution

An acid is a substance that releases ______ in solution.

protons

A molecule is classified as a(n) ______ when it acts as a proton acceptor.

base

Water molecules can form covalent bonds with other water molecules.

false hydrogen

The acidity of a solution refers to the free (unbound) ______ ion concentration.

hydrogen

When a single class of molecule is neither purely hydrophilic nor hydrophobic but has elements of both, it is referred to as a(n) ____ molecule.

amphipathic

The amount of solute present in a unit volume of solution is referred to as the solute

concentration

A molecule that can release protons (H+) into a solution is classified as a(n)

acid

A solution's acidity directly reflects the concentration of its ______ ions.

H+

refers to the amount of solute present in a unit volume of solution.

concentration

The passage of substances into and out of the cell is regulated by the 

cell membrane

The plasma membrane is made up mainly of phospholipids and ______.

proteins

The portion of plasma membranes that acts as the main barrier to the movement of polar molecules across the lipid bilayer of cells is ______

the nonpolar tails of phospholipids

A slightly amphipathic molecule that associates with the fatty acid tails of phospholipids and influences the fluidity of the plasma membrane at different temperatures is called

cholesterol

Which best describes an *integral* membrane protein?

An amphipathic protein that associates with polar and nonpolar regions of the phospholipid bilayer, and cannot be easily extracted.

Selective permeability is a property of ______, and it is defined as ______.

plasma membranes; the regulated movement of specific substances between the intracellular and extracellular fluid compartments

All membranes consist of a double layer of  __ molecules containing embedded _ .

phospholipids and proteins

The polar head groups of plasma membrane phospholipids face______; the nonpolar tails face ______.

the extracellular and intracellular fluid spaces; the interior of the membrane bilayer

Membrane structure is described by the ______-______ model, because proteins are free to move around and form different patterns within a sea of phospholipid molecules.

fluid-mosaic

The close association of the nonpolar rings of molecule X with the fatty acid tails of phospholipids tends to limit the ordered packing of fatty acids in the membrane. Molecule X is known as ____

cholesterol

The type of intercellular junctions in which neighboring cells are connected in a band around the entire circumference of the cell, and which typically create barriers to movement of molecules between epithelial cells are known as 

tight junctions

A peripheral membrane protein is one that ______

is associated only with the polar heads of phospholipids on the inner surface of the plasma membrane and can be easily extracted

_______are disk-shaped connections between cells that involve anchoring proteins known as cadherins, and which provide a strong mechanical attachment of adjacent cells in a tissue.

Desmosomes

gap junction

A gap junction is formed by interlocking proteins that directly connect the cytosols of adjacent cells. PROTEIN CHANNELS

tight junction

A tight junction is a circumferential ring formed by the joining of adjacent cells. TWO MEMBRANE SURFACES TG

Peripheral proteins do not associate with the polar regions of phospholipids.

false

The type of cell junction that holds cells together and seals off the space between adjacent cells making it difficult for substances to pass between cells is a(n)_____  junction.

tight

_____ are intercellular junctions characterized by accumulations of "dense plaques" that serve as disk-shaped anchoring points for cadherin proteins and which create a strong physical attachment between cells.

desmosomes

Which best describes an *integral* membrane protein?

An amphipathic protein that associates with polar and nonpolar regions of the phospholipid bilayer, and cannot be easily extracted.

Which best describes the membrane junctions known as *tight* junctions?

Transmembrane proteins form a band around the apical surface of epithelial cells, that limit the movement of substances between cells.

Most epithelial cells are joined near their apical surfaces by membrane junctions known as _______________ . These limit the movement of substances between cells.

tight junctions

Routes by which body water is gained include ______.

liquids and moist foods

metabolic condensation reactions

Evaporation of water from the skin and the lining of the respiratory passageways is classified as ______ water loss because the person is unaware of its occurrence.

insensible

What are routes by which body water is lost from the body?

Sweat and feces

Menstrual flow 

Insensible routes

Urine

Insensible water loss occurs ______.

by evaporation from the skin and respiratory passages

True or false: The energy for simple diffusion comes from ATP.

False: Simple diffusion does not require ATP. The energy comes from heat which leads to random thermal motion of the molecules.

To calculate the flux you would need to know the ____ of material and the unit of time.

amount

Which of the following would increase the time it takes for diffusion equilibrium to be reached between a cell's intracellular fluid and the blood plasma?

Increasing the distance between the cell and the blood stream

Based on Fick's diffusion equation, the magnitude of net flux across a membrane is ______

proportional to the concentration gradient, membrane permeability, and membrane surface area

The mathematical formula for Fick's first law of diffusion is ______.

J = P × A × (Co − Ci)

Molecules of substances within solids, liquids, and gases are in constant motion, and the source of energy causing this motion is ______

heat

The main barrier that limits the diffusion of polar molecules across a plasma membrane is the ______ of the membrane

hydrophobic core

Flux is defined as ______.

the amount of material moving in one direction between two compartments in a given period of time

The function of the lipid bilayer, in terms of movement of molecules, is to ______ movement of polar substances.

limit

Distance is an important factor in determining the ____ at which molecules diffuse. 

rate

Nonpolar molecules diffuse much more rapidly across plasma membranes because these molecules can dissolve in the nonpolar regions of the membrane occupied by the fatty acid chains of the membrane’s ______.

phospholipids

What are the factors that influence the magnitude of the net flux based on Fick's diffusion equation?

Membrane surface area

Membrane permeability

Magnitude of the concentration gradient

 ______ molecules are lipid-soluble and can easily cross a plasma membrane, while ______ molecules cannot.

nonpolar; polar

Fick's first law of diffusion states that the rate of diffusion of a substance is proportional to its

concentration gradient

Ions require ion channels to move through a membrane because ions are ______

charged

The diffusion of substances across a membrane is limited by the chemical composition of the membrane. Specifically, the membrane has an interior that is ______

hydrophobic

Integral membrane proteins that allow ions to diffuse through the membrane are called ion ____

channels

The lipid bilayer functions as a barrier to the passage of______-soluble molecules.

water

The property of ion channels to only allow certain ions to pass through them is known as

specificity or selectivity

A membrane's permeability to a molecule depends on which of the following?

The lipid solubility of the molecule

The molecular weight of the molecule

The exchange of oxygen and carbon dioxide gases occurs through which type of transport mechanism?

simple diffusion

Which of the following factors influences the net flux of ions across the cell membrane, but does not affect the net flux of nonpolar substances?

the membrane potential

True or false: The lipid bilayer is highly impermeable to all charged molecules.

True. Lipid bilayers are permeable to many lipophilic molecules but not to charged atoms or molecules.

The difference in electrical charge between the inside and outside of a cell membrane is known as the ______

membrane potential

Ions are able to cross the cell membrane by ______

moving through channel proteins

The combination of the forces acting on an ion due to the concentration gradient and the membrane potential is known as the _____________

electrochemical gradient

The lipid bilayer is more permeable to which type(s) of molecule(s)? Select all that apply.

hydrophobic

lipid soluble

nonpolar

True or false: The diffusion of ions is influenced by the same factors that influence the diffusion of other solutes, plus the electrical forces that act upon them and the presence or lack of ion channels.

True: Since ions are charged, they are also influenced by the presence of electrical forces acting on them.

When ion channels change between their open and closed states we can see changes in the membrane's ____ to ions. 

permeability

The separation of the electrical charge that exists across plasma membranes of most cells is known as the membrane 

potential

This type of channel experiences a change in shape when a specific molecule binds to it

Ligand-gated ion channel

When membrane potential changes cause movement of charged regions on channel proteins which alter the shape these channels are identified as _____-gated ion channels. 

voltage

The ion’s electrochemical gradient results from the combination of a membrane ____ and a difference in ion  __ across a membrane.

potential, concentration

Which of the following act as transporters for nutrients to cross the plasma membrane?

integral proteins

Liver cells are able to break down glycogen into glucose, thus causing the intracellular glucose concentration to become higher than the extracellular glucose concentration. What happens to facilitated diffusion of glucose under these conditions?

Facilitated diffusion causes net movement of glucose out of the liver cells.

Ion channels are proteins that can usually be in one of two states. What are the names of the two states?

open/closed

In active transport, the "active" refers to Blank______.

the use of energy to power the movement of molecules across a membrane

Proton pumps hydrolyze ATP to provide the energy to move H+ against its concentration gradient. This is an example of which type of molecular movement?

Primary active transport

_____ are ion channels that open or close in response to changes in the membrane potential.

voltage gated channels

The passage of amino acids and glucose and the nondiffusional movements of ions across cell membranes are mediated by integral membrane proteins known as

transporters

One of the best examples of primary active transport is the movement of sodium and potassium ions across plasma membranes by the transporter called Na+/K+- ______.

ATPase pump

Which is TRUE about facilitated diffusion across a cell membrane?

The net transport by facilitated diffusion will be zero when concentrations of a substance are equal on the two sides of the membrane.

For each molecule of ATP hydrolyzed, the Na+/K+-ATPase pump moves  __ sodium ions out of a cell and  _ potassium ions into a cell

3;2

In a typical example of secondary active transport, the energy required for the movement of a solute across a membrane against its concentration gradient is most directly obtained from ______

movement of another solute like Na+ down its concentration gradient

Primary active transport is directly achieved by hydrolysis of ______

ATP

Ultimately, the energy for secondary active transport is derived from metabolism in the form of the _____ that is used by the Na+/K+-ATPase to create the Na+ concentration gradient.

ATP

All cells have a primary active transporter that pumps ______.

Na+ out of cells and K+ into cells