Cell Physiology Flashcards
Which of the following enzymes may be directly activated by ligand binding to G protein-coupled receptors?
Protein kinase A
All answers are correct
Protein kinase C
Phospholipase C
Phospholipase C
Which of the following situations does not represent a homeostatic mechanism?
During a hot summer day, a person sweats a lot and keeps body temperature the same.
As age increases, the skin loses its elasticity and becomes wrinkled.
In a cold day, a person shivers to increase production of body heat.
Eating a large serving of salty food increases salt content in the urine.
As age increases, the skin loses its elasticity and becomes wrinkled
The property of adaptability allows organisms to:
maintain a state of equilibrium
replace regulatory systems.
modify their responses.
rank multiple control systems
Modify their responses
The Na+/Ca2+ exchanger couples the efflux of calcium out of the cell to the influx of sodium into the cell. If inhibition of the Na+/K+-ATPase stops the Na+/Ca2+ exchanger, one can state that Na+/Ca2+ exchange is by:
passive diffusion.
facilitated diffusion.
primary active transport.
secondary active transport
secondary active transport
Which of the following 1 L solutions has the highest water concentration?
50 mM glucose, 150 mM NaCl, 10 mM CaCl2
130 mM sucrose, 50 mM KCl, 50 mM CaCl2
300 mM glucose, 25 mM NaCl, 10 mM CaCl2
40 mM sucrose, 50 mM NaCl, 100 mM KCl, 1 mM CaCl2
40 mM sucrose, 50 mM NaCl, 100 mM KCl, 1 mM CaCl2
Which of the following is a correct statement?
The % of total body water is always 60% of body weight.
Water does not move between compartments.
Total body water is proportional to lean body mass.
Increased body fat content increases water content as well.
Total body water is proportional to lean body mass
Which of the following is more likely to act via G protein-coupled receptors?
Thyroid hormone
Peptide hormones
Progesterone
Cortisol
Peptide hormones
Consider the possible relationships between the rate of flux of a molecule and the concentration gradient across the cell membrane shown in the graph below:
Which of the lines represents the function of the Na+/K+ pump) and which the movement of glucose via glucose transporters (e.g., GLUT2), respectively?
Parabolic increase
Which of the following cells do not have a nucleus?
Smooth muscle cells
Intestinal epithelial cells
Neurons
Red blood cells
Red blood cells
Pores and channels are:
peripheral membrane proteins.
gated.
binding sites for hormones.
integral membrane proteins.
integral membrane proteins
Which of the following best describes the role of endocytosis on water and solute movement?
It allows the entry of large macromolecules.
It serves to import lipid-soluble compounds.
It serves to release neurotransmitters.
It couples facilitated diffusion to receptors.
It allows the entry of large macromolecules
Which of the following statements about extracellular signals is true?
All signals are small and lipophilic.
Signals can be peptides and proteins.
Signals bind to cellular DNA.
All signals act on intracellular receptors.
Signals can be peptides and proteins
Hydrocortisone (a steroid hormone) is used topically to treat poison ivy because it decreases the synthesis of prostaglandins and leukotrienes. Based on its chemistry, hydrocortisone is prepared in:
injectable form.
an oil-based cream.
pills and capsules.
a water-based lotion.
an oil-based cream
A female subject continuously recorded her temperature for 30 days. She found that her body temperature fluctuated between 37.5C during the day and 36.9C at night. Which of the following is most likely true?
Warmer daytime temperatures slightly increase her body temperature.
She may have an infection because she has a slight fever during the day.
Her body temperature drops at night because sleep blunts neuronal reflexes.
Her body temperature set point changes during the day and night.
Her body temperature set point changes during the day and night
A UK laboratory has discovered a new hormone. The investigators determined that the new hormone is a small lipophilic molecule that is transported in the blood bound to proteins. Based on this information, you predict that the new hormone:
binds to intracellular receptors.
activates phospholipase C.
binds to G protein-coupled receptors.
inhibits gene transcription.
Binds to intracellular receptors
The processes of facilitated diffusion and active transport share the following characteristic:
they depend on the Na+/K+-ATPase activity.
both use membrane antiporter molecules.
they need specialized membrane transport molecules.
both use ATP to move molecules against their gradients.
They need specialized membrane transport molecules
Dr. Chemist developed a hydrophilic non-ionic, non-dissociable fluorescent dye “X”. In a separate experiment, Dr. Chemist concluded that “X” does not diffuse into human cells. If human red blood cells are placed in a solution of 50 mM NaCl, 40 mM CaCl2, and 100 mM “X”, what would happen?
The cells will shrink first, and then swell.
The cells will shrink.
The cells will not change.
The cells will burst.
The cells will shrink
When a chemical messenger functions in an endocrine fashion, it:
binds to intracellular receptors that activate adenylate cyclase.
binds to membrane receptors in neighboring cells only.
reaches target cells after being transported in the blood.
activates receptors that stimulate gene transcription.
reaches target cells after being transported in the blood
Emily is a senior living in a dormitory without air conditioning. On a hot summer day, Emily finds herself hot and sweating profusely. Yet, when she checks her temperature with a thermometer, it shows 98.5F (normal for healthy subjects). Which of the following represents an effector in this scenario?
Spinal cord
Temperature-sensitive sensory neuron
Hypothalamus
Sweat gland
Sweat gland
Interferon is a cytokine (chemical signal) produced by cells infected with viruses. When
secreted, it acts on neighboring cells of the same tissue. That means that interferon
behaves as:
a. an endocrine signal.
b. a paracrine signal.
c. an autocrine signal.
d. an exocrine signal.
a paracrine signal
In contrast to a steady state, in a state of equilibrium:
a. energy is used to hold a parameter at a certain value.
b. the parameter must be held at a fixed value.
c. two open systems interact with each other.
d. the parameter does not need to be regulated.
the parameter does not need to be regulated
Which of the following statements about steady states is correct?
a. Inputs must equal outputs.
b. Parameters cannot change.
c. Positive balances are common.
d. They are always regulated by positive feedback.
inputs must equal outputs
Compared to the plasma, the interstitial fluid has:
a. less sodium, more proteins.
b. more calcium, same chloride
c. less proteins, same potassium
d. only potassium, no sodium
less proteins, same potassium
An athlete passed out after running sprints on an extremely hot day. A quick check of his
vital signs showed his body temperature was 102F. A short while later, body temperature
rose to 103F and then to 105F. The athlete was submerged in an iced water bath; that
brought his body temperature to 97F. However, body temperature then increased to 98.6F.
Which of the following statements is most likely TRUE?
a. The rising body temperature is likely due to positive feedback.
b. The body’s temperature set point changed to 105F temporarily to help the athlete run
faster.
c. The athlete lacks the normal homeostatic set point for body temperature.
d. The athlete’s body temperature would have eventually cooled to 98.6F without the ice
bath.
the rising body temperature is likely due to positive feedback
The diffusion coefficient (D) from Fick’s first law of diffusion accounts for:
a. the area available for diffusion.
b. the charge of the molecule.
c. the thickness of the membrane.
d. how lipid soluble the molecule is.
how lipid soluble the molecule is
Compared to a typical eukaryotic cell (300 mOsm/L), a solution consisting of 50 mM CaCl2
+ 50 mM NaHCO3 + 50 mM urea will be:
a. isosmotic.
b. hyperosmotic.
c. it cannot be determined.
d. hyposmotic.
isosmotic
When the transport rate of a membrane transport protein reaches a maximal velocity that
does not change even when the concentration gradient of its substrate increases, we can
say that the transport protein is a:
a. gated channel
b. solute carrier
c. pore
d. sodium channel
solute carrier
Digitalis is a drug that inhibits the Na+ /K+ -ATPase in the cardiac muscle cells. Digitalis
likely_________ Na+ concentration inside cardiac muscle cells. The change in Na+
concentration likely ___________ the secondary active transport of glucose through the
Na+ /glucose symporter.
a. increases — decreases
b. increases — increases
c. decreases — decreases
d. decreases — increases
increases – decreases
Testosterone is a small lipid-soluble steroid hormone; therefore, it is likely to enter cells via:
a. endocytosis.
b. facilitated diffusion.
c. passive diffusion.
d. pinocytosis.
passive diffusion
Which of the following is not a step in a typical cell signaling pathway?
a. Ligand binding induces an intracellular signal.
b. Nuclear receptors have guanylyl cyclase activity.
c. The outcomes include functional changes.
d. Receptors transduce the extracellular signals.
nuclear receptors have guanylyl cyclase activity
In contrast to nuclear receptors, membrane receptors may also induce:
a. changes in protein synthesis.
b. a response to steroid hormones.
c. changes in gene expression.
d. the production of second messengers.
the production of second messengers
Which of the following statements about G protein-coupled receptors is true?
a. The G protein subunits dissociate after ligand binding.
b. All lipid-soluble hormones act via G protein-coupled receptors.
c. Their tyrosine kinase activity starts after autophosphorylation.
d. The receptors contain two enzymatic domains.
the G protein subunits dissociate after ligand binding
The stimulation of adenylyl cyclase activity may result in:
a. increased intracellular levels of cGMP.
b. inhibition of cAMP phosphodiesterase.
c. increased protein kinase A activity.
d. increased diacylglycerol content.
increased protein kinase A activity
