bio chap 5 + 6

whihc body fluid compartment contains higher levels of Na+, Cl-, and HCO3-

both plasma and intersitial fluid

Hypoosmotic solutions have

lower concentrations of solutes than hyperosmotic solutions

the inside of a resting cell is slightly negative relative to the outside this is an example of

electrical disequilibrium

If a 10% sucrose solution is separated from a 20% sucrose solution by a membrane impermeable to sucrose, in which direction will net movement of water occur?

from the 10% sucrose solution to the 20% sucrose solution

what is a unique charcaterisitic of glucose as a solute in a biological system

100% of it is absorbed into the cell from the extracellular fluid.

The tonicity of a solution depends only upon the

concentration of nonpenetrating solutes

the term cellular metabolic energy indicates any biological process requiring

ATP

The sodium potassium pump can transport

only if sodium and potassium are available

Which of the following increased the rate of sodium-potassium transport?

increasing the number of membrane pumps

Which of the following describes the movement of ions by the sodium-potassium pump?

Potassium is moved into the cell.

What is the type of transport supplied by the glucose carriers in the activity?

facilitatetd diffusion

Which of the following can be true of both active transport and facilitated diffusion?

Lipid-insoluble solutes are transported across the membrane by a carrier protein.

Coupled transporters that move solutes in the same direction are called _______.

symporters

Which of the following describes the concentration of ions when the cell is at rest?

The concentration of potassium is higher inside the cell.

Which of the following is the driving force for the sodium-potassium pump?

ATP hydrolysis

Sodium ions are more concentrated in the extracellular fluid than in the intracellular fluid. This is an example of

chemical disequilibrium.

Which is NOT involved in creating the resting potential of a cell?

resting membrane permeability for sodium ions greater than potassium ions

A cell has a mutation in a sodium ion leak channel, and sodium cannot diffuse through this channel. What would you expect to happen to the resting membrane potential difference?

The resting membrane potential difference would be more negative, because there would be less diffusion of positively charged sodium ions into the cell.

Ions are unequally distributed across the plasma membrane of all cells. This ion distribution creates an electrical potential difference across the membrane. What is the name given to this potential difference?

Resting membrane potential (RMP)

Sodium and potassium ions can diffuse across the plasma membranes of all cells because of the presence of what type of channel?

Leak channels

On average, the resting membrane potential is -70 mV. What does the sign and magnitude of this value tell you?

The inside surface of the plasma membrane is much more negatively charged than the outside surface.

The plasma membrane is much more permeable to

K⁺ than to Na⁺.Why?

There are many more

K

⁺

leak channels than

Na

⁺

leak channels in the plasma membrane.

The resting membrane potential depends on two factors that influence the magnitude and direction of

Na

⁺

and

K

⁺

diffusion across the plasma membrane. Identify these two factors.

The presence of concentration gradients and leak channels (Yes! The large number of

K

⁺

leak channels ensures that the membrane is highly permeable to

K

⁺

.

The concentration gradient for

K

⁺

means that

K

⁺

diffuses out of the cell, leaving the inside of the cell negatively charged. In contrast, the relatively few

Na

⁺

leak channels means that the membrane is almost impermeable to

Na

⁺

.

The concentration gradient for

Na

⁺

means that

Na

⁺

will diffuse into the cell through the few leak channels that are open for it. )

What prevents the

Na

⁺

and

K

⁺

gradients from dissipating?

Na

⁺

-K

⁺

ATPase

The concentrations of which two ions are highest outside the cell?

NA+ and Cl-

Let's consider a scenario in which the resting membrane potential changes from minus70 mV to +70 mV, but the concentrations of all ions in the intracellular and extracellular fluids are unchanged. Predict how this change in membrane potential affects the movement of Na Superscript plus. The electrical gradient for Na Superscript plus would tend to move Na Superscript plus __________ while the chemical gradient for Na Superscript plus would tend to move Na Superscript plus __________.

out; in

The resting membrane potential of the cell

-70

Although it plays a role, it is not a primary determinant of the resting membrane potential

NA+ permebeality

The primary determinant of the resting membrane potential

k+ permeability

he point at which there is no net movement of

Upper K Superscript plus

into or out of the cell

-90mV

The membranes of neurons at rest are very permeable to _____ but only slightly permeable to _____.

K+; Na+

During depolarization, which gradient(s) move(s) Na+ into the cell?

both the electrical and chemical gradients

What is the value for the resting membrane potential for most neurons?

-90mV (the resting membrane potential for neurons depends on the distribution of both Na+ and K+ across the cell membrane. The potential is closer to the equilibrium potential of K+ because the cell is more permeable to K+.)

The Na+-K+ pump actively transports both sodium and potassium ions across the membrane to compensate for their constant leakage. In which direction is each ion pumped?

Na+ is pumped out of the cell and K+ is pumped into the cell.

The concentrations of which two ions are highest outside the cell.

Na+ and Cl-

What effect does increasing the extracellular potassium have on the resting membrane potential?

What effect did increasing the extracellular potassium have on the resting membrane potential?

What effect did decreasing the extracellular sodium have on the resting membrane potential?

Only a small change occurred, because the resting neuron is not very permeable to sodium.

The channels that provide for the movement of potassium in the resting neuron are _______.

leakage

Establishing the resting membrane potential requires energy through the use of the _______.

sodium-potassium pump.

Which of the following statements about receptor potentials is FALSE?

They can trigger an action potential.

The receptor proteins respond to stimuli.

Odor molecules can act as stimuli.

The receptor potential is carried by neuroglia.

The receptor potential is carried by neuroglia

Which of the following is NOT a functional region of a neuron?

secretory region

conducting region

receiving region

medullary region

medullary region

The conducting region of the neuron is the _______.

axon

The typical concentration of sodium is _______.

lower than potassium intracellularly

Which of the following describes a change from the resting membrane potential?

a receptor potential, a synaptic potential or an action potential

How do increased glucose availability in a pancreatic beta cell and the closure of the KATP channel lead to exocytosis of insulin-containing vesicles?

The closure of KATP channels causes membrane depolarization and the opening of voltage-gated Ca2+ channels that triggers exocytosis of insulin.

The most significant difference between a paracrine and an autocrine is the

cell that responds to it.

Neurotransmitters and neurohormones

both are released by neurons and both affect only cells with a specific receptor.

Why do some healthy cells fail to respond to a chemical signal?

Some cells lack the appropriate receptors.

DIFFERENCE BETWEEN TYPE 1 AND TYPE 2 DIABETES

Type 1 diabetes occurs when cells of the pancreas stop making insulin while type 2 diabetes occurs when the cells are no longer sensitive to insulin.

If you give a patient who recently developed diabetes a shot of insulin and blood glucose levels do not change, what type of diabetes does he or she most likely have?

TYPE 2

If glucose levels are low, how would you predict activation of the beta cell and insulin release to change?

DECREASE; DECREASE

Which form of cell-to-cell communication uses the direct transfer of electrical and chemical signals?

GAP JUNCTION SIGNALING

Inositol triphosphate is a second messenger that

binds to the calcium channel of the endoplasmic recticulum.

Second messenger molecules directly

change regulation of gene activity.

change enzyme activity.

change the regulation of ion channels.

increase intracellular calcium concentration.

The binding of lipophilic messengers, such as steroid hormones, to their receptors triggers

GENE TRANSCRIPTION

INTRACELLULAR SIGNAL RECCEPTORS

HAVE SLOWER RESPONSES RELATED TO CHANGES IN GENE ACTIVITY

CELL MEMBRANE/EXTRACELLULAR RECEPTORS

RAPID CELLULAR RESPONSE

Which of the following is the best example of a second messenger?

CA2+

Ion channels can be opened or closed through three signal transduction mechanisms. Two of them are extracellular signals and second messengers. What is the third mechanism for opening or closing ion channels?

G PROTEIN ACTION

Choose the correct example of signal amplification.

One hormone molecule causes the activation of more than one second messenger molecule.

The amplification of the signal from a water-soluble hormone is achieved through an increase in _______.

CAMP IN THE CYTOPLASM

Water-soluble hormones affect target cells by binding to __________.

PLASMA MEMBRANE RECEPTORS (Water-soluble hormones bind to specific receptors in the plasma membrane, whereas steroid hormones bind to cytoplasmic receptors.)

How do endocrine hormones reach their target cells?

Hormones are transported through the blood stream to target cells.

What is the role of activated protein kinases?

Phosphorylate proteins.

Cyclic AMP is degraded by

phosphodiesterase (Phosphodiesterase degrades cyclic AMP into AMP.)

When calcium becomes available inside a cell, it comes from

extracellular fluid and intracellular storage.

The ion that controls the widest variety of intracellular activities is __________.

CALCIUM

Protein receptors exhibit

specificity, competition, and saturation.

α-adrenergic receptors have a higher affinity for norepinephrine than for epinephrine. β-adrenergic receptors have a higher affinity for epinephrine than for norepinephrine. Which characteristics of receptor function do these statements describe?

Competition

The neurotransmitter epinephrine __________.

causes some blood vessels to dilate and others to constrict, because different blood vessels have different receptors for epinephrine

Homeostatic control that takes place at the tissue or cell by using paracrine or autocrine signals is called

LOCAL CONTROL

An integrating center

evaluates an incoming signal and compares it with the setpoint.

Which of the following is(are) a difference between endocrine and neural control systems?

speed

specificity

nature of the signal

duration of action

Cannon's second postulate states that some systems of the body are under tonic control. What does this statement mean?

The body has the ability to adjust the levels of regulated variables.

Thermoreceptors in the hypothalamus sense the temperature of the blood. When blood temperature begins to decrease, the hypothalamus releases TRH that stimulates the release of TSH from the anterior pituitary gland. TSH stimulates the thyroid gland to release thyroid hormone (TH). TH stimulates an increase in body temperature, which causes the hypothalamus to decrease release of TRH. Which type of reflex pathway is this thermoregulatory pathway?

Complex neuroendocrine reflex

Which of the following is a similarity between neural and endocrine reflexes?

Stimulus intensity can be increased with increased signal.

Compared with endocrine reflexes, neural reflexes __________.

respond rapidly but are short

Your instructor announces a pop quiz. This stimulates a reflex pathway that stimulates your sympathetic nervous system to increase your heart rate. In this reflex pathway, your heart is the ________.

TARGET