uark physiology exam 1

Which of the following factors can affect the membrane potential? Select two answer choices.

- permeability of the membranes to ions

- concentration of gradients of ions

The electrochemical gradient only influences the movement of potassium ions (K+) across the plasma membrane.

False

Most neuron and muscle cells have a resting membrane potential (set points) of ____.

-70mV

The equilibrium potential for K+ is -90 mV, and the equilibrium potential for Na+ is +66 mV. The actual membrane potential is closer to the ______ equilibrium potential because the resting membrane is more permeable to it. If the membrane becomes ______ permeable to a particular ion, the membrane potential is moved towards that ion's equilibrium potential.

K+; more

Leak channel proteins which are always open for K+ allow K+ to move out of the cell. This means K+ is moving ____ its concentration gradient. The gradient is ____ due to the concentration differences across the membrane.

down; steep

During a chemical reaction, a catalyst increases the rate at which the reaction occurs.

true

The substrate binds to the ______________ of the enzyme.

active site

Enzymes:

catalyze chemical reactions

Insulin decreases glucose concentration and glucagon increases glucose concentrations. In a scenario where blood glucose levels decrease from normal, which of the following changes applies negative feedback to reach the original set point of glucose levels?

decrease in insulin - increase in glucagon

If the amount of sodium in the blood decreases from the set point, what would a negative feedback control mechanism be expected to do?

Increase the amount of sodium in the blood to the set point.

Hypotonic blood plasma will cause the red blood cell to

increase in volume.

Hypertonic interstitial fluid will cause the red blood cell to

shrink

Why do water molecules need aquaporins?

They get stuck in the nonpolar hydrophobic fatty acid interior of the membrane so need protein channels

How does the co-transport mechanism of Na+/glucose work?

It uses the sodium gradient to transport glucose into the cell against its concentration gradient.

In secondary active transport, if the other substance is moved in the same direction as Na+, it is called

cotransport

One substance flows down its concentration gradient, and the energy is harnessed to move another substance up its gradient in the same direction. This best describes

co-transport secondary active transport

Norepinephrine (secondary messenger) binds to a receptor protein which uses ____ to open an ion channel in the membrane?

G proteins

The intracellular fluid includes the fluid inside cells and blood plasma.

False

In a phospholipid bilayer, the phospholipids orient themselves such that:

the hydrophilic heads face outward towards the water, and the hydrophobic tails face inward away from the water.

The effector in this example is the _____.

heart

In order to communicate, hormones regulate via the bloodstream . This type of cell signaling is called:

endocrine

Contraction of ____________ muscle are generally voluntarily controlled.

skeletal

The breakdown of hydrogen peroxide is catalyzed by

catalase

Physiology is the study of

how organisms function

Which of these statements about homeostasis is true?

Negative feedback mechanisms act to correct deviations of a variable around a set point.

The Na+/K+ pump works against the electrochemical gradient. This gradient moves _______ out of the cell, against both gradients. This pump takes energy in the form of ______ which is broken down by an enzyme into _____ and _______.

Na+ ; ATP; ADP; Pi

What is happening at letter D?

Some ions from the extracellular fluid move into the pump and bind per the affinity of the protein

Why are the Na+/K+ pumps needed? Select all that are true.

- These pumps contribute to the potential difference across the plasma membrane

- The extrusion of Na+ is required for osmotic reasons, to prevent the undue osmosis of water into cells.

- The steep Na+ gradient produced by the pumps is needed for secondary active transport

ADP is released causing a shape change to the protein and some ions are exiting the pump to extracellular fluid.

At box C

The Na+/K+ pump transports _______ out of the cell and ________ into the cell per cycle.

3Na+, 2K+

The Na+/K+ pump is constantly transporting ions except when K+ or Na+ channels are open.

False

The active transport of Na+ and K+ re-sets the intracellular concentration such that Na+ is lower than its extracellular concentration, whereas the reverse is true for K+.

True

How do SSRIs primarily affect serotonin levels in the brain?

By preventing the reuptake of serotonin

How does the external temperature affect human body temperature regulation?

The body activates mechanisms like sweating or shivering to maintain temperature.

Refer to the figure above. If you are dehydrated, your blood osmolality is ____________. What is the effect from the trigger of thirst?

increased; H2O taken in

Refer to the figure above. The stimulus required for a increase in plasma osmolality is ______________. In order to increase water intake what part of the feedback system will receive the information from the sensor?

dehydration; integrating center

The stimulus for dehydration is the osmoreceptors.

False

The primary function of epithelial cells includes absorption, secretion, and protection.

True

There is only one specific type of protein channel that transports sodium ions across the cell membrane.

False

Two receptors, A and B, bind the same ligand. The concentration of the ligand required to reach 50 percent saturation is twice as great for receptor B. Therefore the receptors have the same ________, but different ________.

specificity, affinity

Which is the best definiton of affinity?

strength of ligand-protein binding

Which describes the action of a ligand's competitive antagonist?

It blocks the binding of the ligand to its binding site and prevents activation of the protein.

Which is the best definition of the term ligand?

a molecule that binds to a protein

Which of the following would increase saturation for binding sites?

concentration and affinity

A certain protein receptor is capable of binding the epinephrine but does not bind to dopamine, glutamate, or serotonin. This is because the receptor displays what characteristic?

specificity

Passive transport is characterized by:

Movement of substances across a membrane without the need for energy

Why are cells in body organs generally within 100 um of a blood capillary?

to decrease mean diffusion time

The rate of diffusion is influenced by

- membrane surface area.

- membrane permeability.

- the concentration gradient.

urinary system

regulates fluid balance

nervous sytem

Detects and processes information through electrical signals

cardiovascular system

Circulates blood throughout the body

immune system

defends against pathogens

respiratory system

Removes carbon dioxide from the body

endocrine system

secretes hormones

Digestive system

process food for use by the body

osmosis is the movement ___ in attempt to bring solutions inside and outside of a cell into ____. The movement is from the ____ area to the ___ area

water; equilibrium; diluted; concentrated

Homeostasis is best thought of as being a state of

dynamic constancy

All of the following statements about enzymes are true EXCEPT

enzymes are consumed during a chemical reaction

During a chemical reaction, a catalyst increases the rate at which the reaction occurs.

true

By what transport methods does glucose enter most cells

facilitated diffusion

An example of synaptic communication would be:

neurotransmitters

Maryam has fallen ill. Her Body temperature has risen to high levels, her blood pressure is high and her glucose level is low. Which of the following will allow one variable to reach homeostasis?

Apply negative feedback to restore glucose levels in the blood stream by using the hormone glucagon which will raise blood sugar

When you decrease the osmolarity of the intracellular fluid, water will ___. This means there are fewer solutes n the IF

moves into the cell

The primary intracellular cation is

K+

Norepinephrine acts as a

neurotransmitter