Homeostasis refers to body conditions in which
a) the internal environment is constant within narrow limits.
b) energy is released by reactions occurring during growth.
c) input stimuli increase all output stimuli.
d) conditions within the internal environment never change.
e) body fluids always maintain the same composition.
a
Select all of the following statements that are true about negative feedback
mechanisms.
a) One is triggered when blood calcium levels drop below the homeostatic
range.
b) One occurs when Na+ enters a neuronal axon during depolarization.
c) They use muscles and glands as effectors.
d) They occur in the nervous system only.
e) One can cause an increase in sweat production if body temperature is
40⁰C.
a c e
Positive feedback mechanisms:
a) work to decrease a stimulus.
b) include sweating in response to an increase in body temperature.
c) include decreased uterine contractions in response to the release of
oxytocin from the posterior pituitary gland.
d) include shivering in response to a decrease in body temperature.
e) include platelet activation in response to chemical factors released from
activated platelets in a damaged blood vessel.
e
Animal cells inside the human body:
a) can easily survive across a wide range of temperatures.
b) survive because positive feedback mechanisms maintain tightly regulated
extracellular ion concentrations.
c) are very sensitive to changes in temperature, pH, and ion concentrations in
extracellular fluids.
d) are never able to respond to stimuli in the external environment.
e) are described by more than one of the above statements.
c
Which of the following is true of the cell membrane?
a) Membrane carbohydrates are usually located on the inner surface of the
membrane.
b) Receptor proteins transport solutes like glucose into and out of the cell.
c) Small, non-polar molecules such as O2 and CO2, are able to pass freely
across the phospholipid tails of the membrane.
d) Gap junctions form tight junctions that prevent substances from moving
between cells.
e) Water always moves across membranes from areas of high solute
concentration to areas of low solute concentration.
c
Desmosomes:
a) are carrier proteins that allow glucose to enter the cell by diffusion.
b) break down and inactivate neurotransmitter on the outer surface of muscle
fibre membranes.
c) are membrane proteins that join adjacent cells to one another.
d) are glycoproteins on the outer surface of plasma membranes used for cell
identification.
e) are gated ion channel proteins that control ion movement across the
membrane.
c
When a liver cell is placed in pure water
a) the cell is said to be hypotonic to the water.
b) the cell will dehydrate.
c) there will be no net movement of water into the cell.
d) the cell is said to be hypertonic to the water.
e) both a) and b) are true.
d
A red blood cell immersed in a 0.9% NaCl solution
a) does not have an overall gain or loss of fluid.
b) has a cytosol with the same osmotic pressure as the solution.
c) is immersed in a solution that is hypertonic to its cytosol.
d) is described by a) and b).
e) is described by a), b) and c).
d
The sodium-potassium ATPase:
a) is a secondary active transport protein.
b) moves Na+ and K+ across the membrane by diffusion.
c) is a transport protein that uses osmosis to alter concentration gradients
across cell membranes.
d) pumps sodium out of the cell and potassium into the cell.
e) is described by both a) and b).
d
An inhibitory postsynaptic potential (IPSP):
a) can be produced by opening gated ion channels specific for sodium ions.
b) increases the chance that the post-synaptic cell will experience an action
potential.
c) is also called a generator potential.
d) is most often produced when acetylcholine binds to chemically gated
channels.
e) can be produced when chloride ions enter the postsynaptic cell.
e
Which of the following is not involved in establishing the resting membrane
potential?
a) Entry of negatively charged ions from the extracellular fluid into the
cytoplasm.
b) Non-gated K+ channels in the neuronal cell membrane.
c) The activity of the sodium-potassium ATPase pump in the neuronal cell
membrane.
d) Large negatively charged proteins trapped in the cytoplasm.
e) Loss of positively charged ions from the cytoplasm to the extracellular
fluid.
a
Voltage-gated Na+ channels on an axon open when the membrane
a) potential is -70 mV.
b) becomes hyperpolarized.
c) potential reaches a threshold potential of -55mV.
d) repolarizes.
e) is in its resting state.
c
A touch stimulus that is perceived in your shoulder:
a) uses a two neuron pathway to reach the post-central gyrus in the brain.
b) begins with the opening of chemically gated ion channels on the touch
receptor.
c) produces an IPSP in the tactile (Meissner’s) corpuscle
d) opens chemically gated ion channels in the dendrites of a neuron in the
thalamus.
e) is carried directly from the spinal cord to the post-central gyrus by a
second-order neuron.
d
You are walking around outside without any shoes on when you step on a piece of glass with your right foot. Your left leg will experience:
a) a flexor reflex.
b) the activation of a polysynaptic pathway that contracts the quadriceps
femoris muscle.
c) the activation of a polysynaptic pathway that contracts the hamstring
muscles.
d) the activation of an ipsilateral response.
e) an autonomic reflex.
b
Which of the following is not considered a function of the hypothalamus?
a) Control of the sympathetic and parasympathetic nervous systems.
b) Maintenance of body temperature within set-point values.
c) Coordinating hormone release from endocrine glands.
d) Regulation of skeletal muscle contraction in the arms and legs.
e) Control of sleep-wake cycles.
d
Tonic receptors:
a) decrease the rate of action potentials sent to the brain when a stimulus
continues at constant strength.
b) respond only to changes in the frequency or intensity of a stimulus.
c) detect stimuli that are not critically important to the body.
d) always communicate stimuli to the CNS regardless of frequency or
intensity.
e) have the ability to adapt to stimuli that they receive.
d
When gated ion channels specific for sodium are in the “open” position:
a) the neuron is waiting to be stimulated.
b) the neuron may have experienced a mechanical stimulus.
c) they are helping to maintain the resting membrane potential of a neuron.
d) they allow sodium ions to exit the neuron.
e) they cause hyperpolarization of the neuron.
b
Acetylcholine
a) is a neurotransmitter only at the neuromuscular junction.
b) is broken down by monoamine oxidase, which is located on the
postsynaptic membrane.
c) is released at salivary glands by sympathetic postganglionic neurons.
d) diffuses into fibres at myelin sheath gaps (nodes of Ranvier),
generating action potentials.
e) is released by cholinergic neurons and binds to receptors on skeletal
muscle fibre membranes.
e
Preganglionic neurons of the sympathetic nervous system
a) release the neurotransmitter norepinephrine.
b) have cell bodies located within the brain stem.
c) can stimulate the adrenal medulla.
d) directly increase secretion of sweat from sweat glands by releasing
norepinephrine.
e) are adrenergic neurons.
c
A patient could not feel her left arm or left leg and said that they were not
hers. A tumor could be present in the
a) right posterior portion of the occipital lobe.
b) premotor cortex of the left side.
c) general sensory cortex of the right parietal lobe or the thalamus.
d) premotor cortex of the right temporal lobe, or basal nuclei.
e) Broca’s area.
c
Insulin is an example of a water-soluble hormone. Insulin:
a) binds to receptors in the cytoplasm.
b) activates transcription of genes inside of target cells.
c) is released in response to humoral stimuli.
d) binds to a receptor in the target cell nucleus.
e) easily passes through the phospholipid bilayer to enter the cell.
c
Which of the following is not a benefit of second messenger systems?
a) They produce long-lasting effects that persist for days or weeks.
b) They allow rapid responses when time is critical.
c) They can be shut down quickly when the response is no longer
needed.
d) They rapidly activate molecules already present inside of the cell.
e) They allow amplification of a single stimulus.
a
During a fight-or-flight response:
a) the person is experiencing long term stress.
b) heart rate decreases while respiratory rate increases.
c) there is increased blood flow to the skin, causing it to appear red.
d) frequent urination occurs.
e) blood insulin levels are low.
e
Select all of the following statements that are true about the endocrine
system.
a) It can influence the activities of virtually every cell in the body.
b) It releases thyroid hormone as a result of the Alarm reaction of the
General Adaption Syndrome.
c) It acts completely independently of the nervous system.
d) It has effects that are generally of shorter duration than effects of the
nervous system.
e) It regulates growth, metabolism and reproduction.
a e
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1: homeostasis27
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2: cell membrane68
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3: nervous system - electrical properties83
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4: nervous system - sensory pathways43
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5: nervous system - reflex pathways35
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6: nervous system - brain stem functions126
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7: endocrine system - overview59
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8: endocrine system - reproduction67
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9: cell physiology56
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midterm practice32
