Human Physiology exam 6

How does active transport differ from passive transport?

-Active transport must use a carrier molecule, while passive occurs with or without a carrier. -Active transport goes against the concentration gradient, while passive goes along the gradient. -Active transport requires use of ATP that powers specific carrier proteins, which are often called pumps, while passive does not.

functions of Antidiuretic Hormone (ADH).

-Decrease blood osmolality -Stimulate water intake -Increase water retention

Which of the following factors affects the rate of diffusion?

-Size of molecules -temperature -Steepness of the concentration gradient

Check all of the characteristics shared by carrier proteins and enzymes in the cell membrane.

-Specificity -Saturation -Competition

Passive transport

-movement of oxygen from the alveoli into the pulmonary capillaries -movement of water from the plasma to the interstitial fluid -organic molecules, such as glucose, moving into or out of a cell using carrier protein -lipid soluble hormones entering. a target cell

active transport

-movement sodium and potassium during sodium/potassium pump -coupled movement of sodium Into a cell and glucose out of a cell -calcium moving from the cytoplasm to the sarcoplasmic reticulum of skeletal muscle

The extent to which an ion contributes to the value of the equilibrium potential depends on ________.

-the ion concentration inside and outside the cell -the valence of the ion

CONTRANSPORT OF GLUOSE: steps in order

1. sodium and glucose bind to the same carrier protein 2. the carrier protein undergoes a conformational change in shape 3. sodium and glucose move by symport into the cells interior

Arrange the following in the proper order in which they occur. 1. Binding of ligand to receptor site 2. Dissociation of G protein subunits 3. Diffusion of calcium ions into the cell

123

During one cycle, the sodium-potassium pump binds and moves ________.

3 Na+ out of and 2 K+ into the cell

The osmolality of a red blood cell is __________.

300 mOsmoles

Choose the statement that correctly describes a ligand.

A small molecule that binds to a membrane-bound receptor

Which of the following is a component of passive transport

Can occur with or without a carrier molecule

Which of the following statements accurately describes the extracellular fluid?

Extracellular fluid includes blood plasma and interstitial fluid.

Initially, bound to the alpha subunit of the G-protein is a(n) __________.

GDP molecule

The activation/inactivation of G proteins occurs as a result of ________.

GDP/GTP exchange and GTP hydrolysis

What is the source of energy used to power the sodium-potassium pump?

Hydrolysis of ATP

A student has had a severe case of stomach upset with fever, vomiting, and diarrhea for several days, and ends up in the emergency room. What type of IV solution should be given to the student?

Hypotonic

Facilitated diffusion

Includes the movement of small organic molecules through a protein located within the plasma membrane

simple diffusion

Involves the movement of lipid soluble molecules from a high concentration to a low concentration

Which of the following statements about the protein calmodulin is TRUE?

It binds to Ca 2+ ions to mediate a cellular response.

A slice of potato is placed in a hypertonic salt water solution. In a few hours, what would be the appearance of the potato slice?

It would be shriveled.

Which of the following is a function of the gradient created by the Na+/K+ pump?

Produces electrochemical gradient across the cell membrane

Which of the following correctly characterizes resting membrane potential?

Slightly more positive than the potassium equilibrium potential

Which of the following will pass through a cell membrane most easily?

Small nonpolar molecules

What does the hydrolysis of ATP do in a Ca2+ pump or Na+/K+ pump?

Temporarily blocks both exits of the carrier

aquaporins(specific proteins)

The protein channels in plasma membrane that permit osmosis to occur across the membrane. In certain tissues, aquaporins are inserted into the plasma membrane in response to stimulation by antidiuretic hormone. ex. the collecting ducts of the kidney,

Methods of Carrier-mediated transport:

a. Facilitated diffusion b. Active transport

Non-carrier-mediated transport

a. Simple diffusion of lipid-soluble molecules through the phospholipid layers of the plasma membrane B. Simple diffusion of ions through the protein channel in the plasma membrane C. Simple diffusion of water molecules (osmosis) through aquaporin (water) channels in the plasma membrane

Facilitated diffusion requires __________.

carrier proteins

The extracellular matrix includes ________.

collagen

Red blood cells in an isotonic solution are __________.

disc-shaped

If a plasma membrane was only permeable to calcium ions, the resting membrane potential would be ________.

equal to the equilibrium potential for Ca2+

The transport of glucose from the blood across plasma membranes occurs by facilitated diffusion. Facilitated diffusion, like simple diffusion, is powered by the thermal energy of the diffusing molecules and involves net transport from the side of higher concentration to the side of lower concentration. ATP is not required for either facilitated or simple diffusion.

facilitated diffusion= The carrier-mediated transport of molecules through the cell membrane along the direction of their concentration gradients. It does not require the expenditure of metabolic energy.

Integrins are ________.

glycoproteins that are found extending through the plasma membrane

A red blood cell placed into a 0.3 m-solution of urea (a penetrating solute) will exhibit __________.

hemolysis and be destroyed

Facilitated diffusion occurs __________.

in either direction depending on the concentration gradient of the molecule

If a regulatory molecule is nonpolar, the receptor protein would most likely be found ________.

in the cytoplasm

What structures connect the intracellular and extracellular compartments through the plasma membrane?

integrins

Which fluid compartment contains water found within body cells?

intracellular compartment

Human erythrocytes function best in a(n) __________ solution.

isotonic

active transport

movement of molecules across the plasma membranes of epithelial cells from a low concentration to a high concentration

Two solutions are said to differ in __________ if they have different concentrations of nonpenetrating solutes.

osmolarity

Primary active transport involves a conformational change in the carrier protein. The most immediate stimulus for this is ________.

phosphorylation within the cell

The ion that has the greatest influence on a cell's resting membrane potential is __________.

potassium

A polar regulatory molecule will require a __________ to cause changes in the cell.

second messenger

A red blood cell placed in a hypertonic solution will __________.

shrink/ shrivel and become crenated

Cells continually generate carbon dioxide and must get rid of it. The mechanism whereby carbon dioxide moves out of the cell is called ________.

simple diffusion

The sodium-potassium pump functions to pump ________.

sodium ions out of the cell and potassium ions into the cell

Once acetylcholine binds to the receptor, it causes ________.

sodium ions to diffuse through and enter the cell

Facilitated diffusion is used to transport __________.

sugars

As a result of the ligand binding to its site, ________.

the G-protein changes conformation and GTP replaces the GDP on the alpha subunit

When sugar is mixed with water, equilibrium is reached when ________.

the dissolved sugar molecules are evenly distributed throughout the solution

When the acetylcholine binds to the receptor sites, __________.

the sodium channels open

When the acetylcholine receptor sites are not occupied, __________.

the sodium channels remain closed

Osmosis is best defined as the movement of __________.

water molecules from an area of low solute concentration to an area of higher solute concentration