Exam II- Bio 208
Questions and Answers
- 1.
Arrange the following stpes involved inthe generation of an action potential into their proper sequence: a. Sodium channels are inactived b. Potassium channels open and potassium oves out of the cell c. Sodium channels regain their normal properties d. Graded depolarization brings area of excitable membrane to threshold e. A temperary hyperpolarization occurs f. Sodium channel activation occurs g. Sodium ions enter the cell and depolarization occurs
- A.
D,f,g,c,b,e,a
- B.
E,g,d,a,b,c,f
- C.
B,d,f,g,a,c,e
- D.
D,f,g,a,b,c,e
- E.
D,b,e,f,g,c,a
Correct Answer
D. D,f,g,a,b,c,e -
- 2.
During salatory conduction, (APs=action potentials)
- A.
APs move in all directions along an axon
- B.
Local currents depolarize adjacent areas of membrane so that APs continue to form along the membrane
- C.
APs produce a local current that is strong enough to spread along the length of the axon
- D.
Local potentials produce a continuous outward flow of potassium ions
- E.
APs occur between successive nodes along the length of stimulated axon
Correct Answer
E. APs occur between successive nodes along the length of stimulated axonExplanation
During salatory conduction, action potentials (APs) occur between successive nodes along the length of the stimulated axon. This is because salatory conduction is a form of rapid conduction in myelinated axons, where the APs "jump" from one node of Ranvier to the next. This allows for a faster and more efficient propagation of the AP along the axon, as the myelin sheath insulates the axon and forces the electrical signal to "leap" between the nodes. This process reduces the energy required for conduction and speeds up the transmission of the signal.Rate this question:
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- 3.
Multiple Sclerosis (MS) is associated with a loss of myelin. MS may then involve:
- A.
Oligodendrocytes
- B.
Astrocytes
- C.
Microglia
- D.
Ependymal
- E.
Reshaw neruons
Correct Answer
A. OligodendrocytesExplanation
In Multiple Sclerosis (MS), the immune system mistakenly attacks the protective covering of nerve fibers called myelin. Oligodendrocytes are the cells responsible for producing and maintaining myelin in the central nervous system. Therefore, in MS, the loss of myelin is directly associated with the dysfunction or damage to oligodendrocytes. This loss of myelin disrupts the normal transmission of nerve signals, leading to the symptoms experienced by individuals with MS.Rate this question:
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- 4.
The later part of the rising (depolarizing) phase of the action potential is mediated by a(n) )____ ion membrane channel
- A.
Ligand- gated
- B.
Voltage-gated
- C.
Leak
- D.
Active pump
- E.
Facilitated diffusion
Correct Answer
B. Voltage-gatedExplanation
The later part of the rising phase of the action potential is mediated by a voltage-gated ion membrane channel. Voltage-gated channels open and close in response to changes in the voltage across the membrane. In the rising phase of the action potential, the membrane potential becomes more positive, triggering the opening of voltage-gated sodium channels, allowing sodium ions to enter the cell and depolarize the membrane. This leads to the rapid upswing of the action potential. Therefore, the correct answer is voltage-gated.Rate this question:
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- 5.
Which of the following is TRUE of a graded potential?
- A.
The potential is propagated with a constant magnitude
- B.
The potential is all-or-none
- C.
Stimulus causes ion channels to open changing membrane permeability
- D.
No summation of potentials occurs
- E.
The potential has a refractory period
Correct Answer
C. Stimulus causes ion channels to open changing membrane permeabilityExplanation
A graded potential is a change in the membrane potential that can vary in magnitude. It is not propagated with a constant magnitude like an action potential. When a stimulus occurs, it causes ion channels to open, which changes the permeability of the membrane. This allows ions to flow across the membrane, resulting in a change in the membrane potential. Graded potentials can summate, meaning that multiple graded potentials can add together to create a larger change in membrane potential. Graded potentials do not have a refractory period like action potentials do.Rate this question:
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- 6.
Opening of Na+ channels in the membrane of a neuron normally results in
- A.
Hyperpolarization
- B.
Repolarization
- C.
Depolarization
- D.
Increased negative charge inside neuron
- E.
None of these
Correct Answer
C. DepolarizationExplanation
The opening of Na+ channels in the membrane of a neuron normally results in depolarization. When the Na+ channels open, sodium ions rush into the neuron, causing the inside of the neuron to become more positive. This shift in charge disrupts the resting membrane potential and triggers an action potential, which allows the neuron to transmit an electrical signal. Hyperpolarization refers to an increase in the negative charge inside the neuron, while repolarization refers to the restoration of the resting membrane potential after depolarization.Rate this question:
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- 7.
A resting (trans) membrane potential of a cell has a valuue of approximatly
- A.
-9 V
- B.
+9 V
- C.
0 mV
- D.
+70 mV
- E.
-70 mV
- F.
-80 mV
Correct Answer
E. -70 mVExplanation
The resting (trans) membrane potential of a cell refers to the electrical charge difference across the cell membrane when the cell is at rest. A negative value indicates that the inside of the cell is more negative compared to the outside. A value of approximately -70 mV is within the typical range for resting membrane potential in most cells. This negative potential is maintained by the balance of ions across the membrane, with higher concentrations of negatively charged ions inside the cell and positively charged ions outside. This potential is important for various cellular processes, including the transmission of nerve impulses.Rate this question:
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- 8.
What prevents an action potential from traveling in both directions down an axon?
- A.
The resting potential
- B.
Ligand-gated channels
- C.
Graded potentials
- D.
The refractory period
- E.
Leak channels
Correct Answer
D. The refractory periodExplanation
The refractory period prevents an action potential from traveling in both directions down an axon. During this period, the axon is temporarily unable to generate another action potential, as the voltage-gated sodium channels are inactivated and unable to open. This ensures that the action potential moves in one direction, from the axon hillock towards the axon terminals, allowing for efficient and unidirectional transmission of signals in the nervous system.Rate this question:
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- 9.
A person whose genetic makeup or training makes then a better SPRINTER than a marathon runner probably has ____ in their leg muslces
- A.
More red muscle fibers
- B.
More white muscle fibers
- C.
More noncontractile fibers
- D.
Equal amounts of read and white m.fibers
- E.
Less myoglobin than hemoglobin
Correct Answer
B. More white muscle fibersExplanation
A person who is genetically predisposed or trained to be a better sprinter than a marathon runner likely has more white muscle fibers in their leg muscles. White muscle fibers are associated with fast, powerful movements and anaerobic activities like sprinting, while red muscle fibers are associated with endurance and aerobic activities like long-distance running. Therefore, having more white muscle fibers would give the person an advantage in sprinting rather than marathon running.Rate this question:
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- 10.
The smooth but steady increase in muscle tension (submaximally) produced by increasing the number of active motor units is called:
- A.
Recruitment
- B.
Tetany
- C.
A twitch
- D.
Relaxation
- E.
Recovery
Correct Answer
A. RecruitmentExplanation
Recruitment refers to the process of increasing the number of active motor units in order to produce a smooth but steady increase in muscle tension. This is achieved by activating additional motor units as the intensity of the muscle contraction increases. This allows for a gradual increase in muscle force without causing a sudden twitch or tetany. Relaxation and recovery, on the other hand, refer to the processes of releasing tension and recovering after muscle contraction, respectively.Rate this question:
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- 11.
____ is involved in BOTH synaptic transmission and excitation-contraction coupling?
- A.
Myosin
- B.
Chloride
- C.
Calcium
- D.
Tropomyosin
- E.
T-tubules
Correct Answer
C. CalciumExplanation
Calcium is involved in both synaptic transmission and excitation-contraction coupling. In synaptic transmission, calcium ions play a crucial role in the release of neurotransmitters from the presynaptic neuron into the synaptic cleft. This allows for the transmission of signals between neurons. In excitation-contraction coupling, calcium ions are released from the sarcoplasmic reticulum in muscle cells, triggering muscle contraction. Calcium ions bind to troponin, causing a conformational change in tropomyosin, which exposes the myosin-binding sites on actin filaments, allowing for the interaction between actin and myosin and subsequent muscle contraction.Rate this question:
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- 12.
Which striated muscle band is directly adjacent to the Z-line?
- A.
A-band
- B.
H-band
- C.
T-band
- D.
M-band
- E.
I-band
Correct Answer
E. I-bandExplanation
The I-band is directly adjacent to the Z-line in striated muscle. The I-band contains only thin filaments and is responsible for the light appearance of the muscle under a microscope. It is the region where actin filaments are anchored to the Z-line, which helps to stabilize the structure of the muscle fiber.Rate this question:
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- 13.
During relaxation, muscles return to their original length NOT because of
- A.
Renshaw inhibition
- B.
Elastic forces
- C.
The pull of gravity
- D.
The contraction of opposing muscles
- E.
The elastic nature of the sarcrolemma
Correct Answer
A. Renshaw inhibitionExplanation
During relaxation, muscles return to their original length due to the elastic forces present in the muscle fibers and the pull of gravity. The contraction of opposing muscles also helps in the relaxation process as it counteracts the contraction of the muscle being relaxed. However, Renshaw inhibition is not responsible for the return of muscles to their original length during relaxation. Renshaw inhibition is a mechanism in the spinal cord that prevents excessive muscle contraction by inhibiting the motor neurons that stimulate the muscle.Rate this question:
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- 14.
At rest, active sites on the actin are blocked by
- A.
Myosin molecules
- B.
Calcium ions
- C.
ATP molecules
- D.
Troponin molecules
- E.
Tropomyosin molecules
Correct Answer
E. Tropomyosin moleculesExplanation
Tropomyosin molecules block the active sites on the actin when the muscle is at rest. This prevents the myosin molecules from binding to the actin and initiating muscle contraction. When calcium ions are released in response to a nerve impulse, they bind to the troponin molecules, causing a conformational change that moves the tropomyosin molecules away from the active sites on actin, allowing myosin to bind and initiate muscle contraction. Therefore, tropomyosin plays a crucial role in regulating muscle contraction by blocking the active sites on actin in the absence of calcium ions.Rate this question:
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- 15.
Tropomyosin wraps itself around which other muscle element?
- A.
Myosin
- B.
F-actin
- C.
Troponin
- D.
Titin
- E.
H-band
Correct Answer
B. F-actinExplanation
Tropomyosin wraps itself around F-actin, which is another muscle element. F-actin, also known as filamentous actin, is a protein that forms the main component of the thin filaments in muscle fibers. Tropomyosin is a regulatory protein that lies in the groove of F-actin, preventing the interaction between actin and myosin. This interaction is crucial for muscle contraction. Therefore, the correct answer is F-actin.Rate this question:
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- 16.
The 'powerstroke' in skeletal muslce contraction is directly associated with:
- A.
Myosin head pivots at joint pulling action
- B.
AP movement down t-tubule
- C.
Calcium release from SR
- D.
AP movement along sacrolemma
- E.
Calcium binding to troponin
Correct Answer
A. Myosin head pivots at joint pulling actionExplanation
The powerstroke in skeletal muscle contraction is directly associated with the myosin head pivoting at the joint, which results in the pulling action. This movement is triggered by the binding of ATP to the myosin head, causing it to detach from actin. As ATP is hydrolyzed to ADP and inorganic phosphate, the myosin head undergoes a conformational change and pivots, pulling the actin filament towards the center of the sarcomere. This movement is responsible for muscle contraction and the generation of force.Rate this question:
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- 17.
We can distinguish between sensation orginating in different body areas because
- A.
Receptors from each body region synapse in specific brain regions
- B.
Snesory neurons carry only one type of information
- C.
Incoming sensory information is first assessed by the thalamus
- D.
Different types of sensory receptors produce different types of AP's
- E.
Sensory neurons in different parts of the body
Correct Answer
A. Receptors from each body region synapse in specific brain regionsExplanation
Receptors from each body region synapse in specific brain regions, allowing us to distinguish between sensations originating in different body areas. This is because sensory information from different body regions is transmitted to specific areas in the brain that are responsible for processing that specific type of sensory information. By analyzing which brain regions are activated, we can identify the specific body area from which the sensation originated.Rate this question:
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- 18.
Diffusion across the Arachnoid Granulations returns excess CSF to
- A.
The third ventricle
- B.
Arterial circulation
- C.
Venous circulation
- D.
The fourth ventricle
- E.
The central canal
Correct Answer
C. Venous circulationExplanation
Arachnoid granulations are small protrusions of the arachnoid membrane into the venous sinuses of the brain. They act as one-way valves, allowing cerebrospinal fluid (CSF) to be reabsorbed into the bloodstream. Therefore, diffusion across the arachnoid granulations returns excess CSF to the venous circulation, allowing it to be transported away from the brain and eventually eliminated from the body.Rate this question:
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- 19.
Soon after a person dies (and loses all ATPs), their skeletal muscles:
- A.
Flex with significant force
- B.
Stiffen from actin and myosin binding
- C.
Extend with significant force
- D.
Get smaller in volume
- E.
Get larger in volume
Correct Answer
B. Stiffen from actin and myosin bindingExplanation
When a person dies, their skeletal muscles stiffen due to a process called rigor mortis. Rigor mortis occurs because after death, the body is no longer able to produce ATP, which is necessary for muscle relaxation. Without ATP, the actin and myosin filaments in the muscles remain bound together, causing the muscles to become stiff and rigid. This stiffness typically starts a few hours after death and peaks within 24-48 hours. Therefore, the correct answer is that the skeletal muscles stiffen from actin and myosin binding.Rate this question:
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- 20.
Each of the following are characteristics of smooth muscles EXCEPT
- A.
Have small diameters and lengths compared with skeletal muscles
- B.
Have actin and myosin
- C.
Have autorhythmicity
- D.
Have striations
- E.
Little fatigue with prolong contraction
Correct Answer
D. Have striationsExplanation
Smooth muscles do not have striations, unlike skeletal muscles. Striations are alternating light and dark bands that are seen in skeletal and cardiac muscles due to the arrangement of contractile proteins. Smooth muscles lack this organization, resulting in a smooth appearance under a microscope. Therefore, the absence of striations is a characteristic of smooth muscles.Rate this question:
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- 21.
Which of the following is responsible for reciprocal inhibition?
- A.
Sensory neurons
- B.
Interneurons in the spinal cord
- C.
Extensor neurons
- D.
Motor neurons
- E.
None of these
- F.
All of these
Correct Answer
B. Interneurons in the spinal cordExplanation
Interneurons in the spinal cord are responsible for reciprocal inhibition. Reciprocal inhibition is a neural mechanism that involves the simultaneous relaxation of one muscle and the contraction of its antagonist muscle. This allows for smooth and coordinated movement by preventing conflicting muscle contractions. Interneurons in the spinal cord receive input from sensory neurons and transmit signals to motor neurons, coordinating the activity of different muscle groups. Therefore, interneurons in the spinal cord play a crucial role in reciprocal inhibition.Rate this question:
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- 22.
Arrange the following steps involved in a reflex arc into their proper sequence: a. activation of a sensory neuron b. activation of a motor neuron c.response by an effector d.arrival of a stimulus e.information processing
- A.
D,a,e,b,c
- B.
D,e,c,a,b
- C.
A,c,d,e,b
- D.
C,a,d,e,b
- E.
D,c,a,e,b
Correct Answer
A. D,a,e,b,cExplanation
The correct sequence of steps involved in a reflex arc is as follows:
1. Arrival of a stimulus (d)
2. Activation of a sensory neuron (a)
3. Information processing (e)
4. Activation of a motor neuron (b)
5. Response by an effector (c)
In a reflex arc, the first step is the arrival of a stimulus which triggers the activation of a sensory neuron. The sensory neuron then carries the information to the central nervous system for processing. After processing, the motor neuron is activated, leading to a response by the effector, which is the final step in the reflex arc.Rate this question:
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- 23.
People perceive different intensities of light when their brains recieve different ___.
- A.
Action potentials send to various regions of the brain
- B.
Shapes of action potentials
- C.
Sizes of action potentials
- D.
Wavelengths of light
- E.
Rates of action potentials
Correct Answer
E. Rates of action potentialsExplanation
The correct answer is rates of action potentials. When light enters the eye, it is converted into electrical signals by specialized cells called photoreceptors. These signals, known as action potentials, are then transmitted to the brain. The intensity of the light is encoded in the rate at which these action potentials are generated. Higher rates of action potentials indicate brighter light, while lower rates indicate dimmer light. Therefore, people perceive different intensities of light when their brains receive different rates of action potentials.Rate this question:
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- 24.
Part of the brian most closely associated with emotions is:
- A.
Cerebrum
- B.
Thalamus
- C.
Hypothalamus
- D.
Cerebellum
- E.
Medulla oblongata
Correct Answer
C. HypothalamusExplanation
The hypothalamus is the part of the brain most closely associated with emotions. It plays a crucial role in regulating emotions, as well as various bodily functions such as temperature regulation, hunger, thirst, and sleep. It controls the release of hormones that influence our emotions and is also involved in the stress response. Damage to the hypothalamus can lead to emotional disturbances and affect our overall emotional well-being.Rate this question:
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- 25.
Overseeing the postural muscles of teh body and making rapid adjustments to maintain balance and equilibrium are functions of the
- A.
Cerebrum
- B.
Midbrain
- C.
Pons
- D.
Cerebellum
- E.
Medulla
Correct Answer
D. CerebellumExplanation
The cerebellum is responsible for overseeing the postural muscles of the body and making rapid adjustments to maintain balance and equilibrium. It receives information from the sensory systems, spinal cord, and other parts of the brain to coordinate movements and ensure smooth and coordinated muscle activity. The cerebellum plays a crucial role in motor control and coordination, allowing us to maintain balance and perform precise movements.Rate this question:
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- 26.
The cell bodies of the sympathetic preganglionic neurons are in the:
- A.
Lateral gray horns of T1 through L2 region of the spinal cord
- B.
Brain stem and sacral area of the spinal cord
- C.
Lateral gray horns of the cervical region of the spinal cord
- D.
Anterior gray horns of the entire spinal cord
- E.
Lateral gray horns of the entire spinal cord
Correct Answer
A. Lateral gray horns of T1 through L2 region of the spinal cordExplanation
The sympathetic preganglionic neurons are responsible for transmitting signals from the central nervous system to the sympathetic ganglia. These neurons have their cell bodies located in the lateral gray horns of the T1 through L2 region of the spinal cord. This is where the preganglionic neurons originate before synapsing with the postganglionic neurons in the sympathetic ganglia. Therefore, the correct answer is the lateral gray horns of T1 through L2 region of the spinal cord.Rate this question:
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- 27.
Activity of the parasympathetic ANS mainly
- A.
Is directed towards different sets of organs than the sympathetic ANS
- B.
Is involved in the fight or flight response
- C.
Increases when someone turns into the hulk
- D.
Increases blood glow to skeletal muscles
- E.
Increases while calmly digesting dinner
Correct Answer
E. Increases while calmly digesting dinnerExplanation
The parasympathetic ANS is responsible for the "rest and digest" response in the body. During this state, the body is in a relaxed state and focuses on activities such as digestion. The parasympathetic ANS increases its activity during this time, allowing for increased blood flow to the digestive organs and promoting optimal digestion. This is why the activity of the parasympathetic ANS increases while calmly digesting dinner.Rate this question:
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- 28.
The cell bodies of the parasympathetic preganglionic neurons are found in the:
- A.
Lateral gray horns of T1 through L2 region of the spinal cord
- B.
Brain stem and lateral gray horns of the sacral area of the spinal cord
- C.
Lateral gray horns of the cervical region of the spinal cord
- D.
Anterior gray horns of the entire spinal cord
- E.
Lateral gray horns of the entire spinal cord
Correct Answer
B. Brain stem and lateral gray horns of the sacral area of the spinal cordExplanation
The parasympathetic preganglionic neurons are responsible for transmitting signals from the central nervous system to the autonomic ganglia in the parasympathetic division. These neurons have their cell bodies located in specific regions of the central nervous system. In this case, the correct answer states that the cell bodies of the parasympathetic preganglionic neurons are found in the brain stem and lateral gray horns of the sacral area of the spinal cord. This means that the cell bodies are located in both the brain stem and a specific region of the spinal cord, which is the sacral area.Rate this question:
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- 29.
Of the 31 pairs of spinal nerves, each one monitors a particular _____.
- A.
Organ
- B.
Muscle
- C.
Dermatome
- D.
Brain region
- E.
Sesnory modality (like vision or hearing)
Correct Answer
C. DermatomeExplanation
Each pair of spinal nerves in the human body is responsible for monitoring a specific region of the skin called a dermatome. These dermatomes are divided along the length of the body and help to transmit sensory information from the skin to the spinal cord and brain. By monitoring specific dermatomes, the spinal nerves can detect sensations such as touch, temperature, and pain in different areas of the body.Rate this question:
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- 30.
When General A. Jackson said "Don't fire until you see the whites of their eyes!" he was referring to their:
- A.
Iris
- B.
Sclera
- C.
Cornea
- D.
Ciliary body
- E.
Choroid
Correct Answer
B. ScleraExplanation
General A. Jackson's statement "Don't fire until you see the whites of their eyes!" refers to the sclera. The sclera is the white, outer layer of the eye that is easily visible when looking at someone's eyes. The statement implies that the soldiers should wait until the enemy is close enough that they can clearly see the whites of their eyes before firing their weapons. This would ensure that their shots are accurate and have the highest chance of hitting the target.Rate this question:
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- 31.
Nerve fibers that are considered adrenergic secrete _____ as the neurotransmitter
- A.
Acetylcholine
- B.
Glutamate
- C.
Substance P
- D.
Serotonin
- E.
Norepinephrine
Correct Answer
E. NorepinephrineExplanation
Nerve fibers that are considered adrenergic secrete norepinephrine as the neurotransmitter. Norepinephrine, also known as noradrenaline, is a neurotransmitter that plays a role in the sympathetic nervous system, which is responsible for the fight-or-flight response. It is involved in regulating various physiological processes such as heart rate, blood pressure, and stress response. Norepinephrine is released in response to stress or danger and helps prepare the body for action.Rate this question:
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- 32.
What eye part changes in order to focus images at different distances onto retina?
- A.
Contraction of pupillary muscles
- B.
Shape of anterior chamber
- C.
Shape of posterior chamber
- D.
Shape or size of lens
- E.
Shape or size of pupil
Correct Answer
D. Shape or size of lensExplanation
The lens of the eye changes its shape or size in order to focus images at different distances onto the retina. When focusing on objects that are close, the lens becomes thicker and more curved, allowing the eye to bend light rays more strongly and bring the image into focus. For objects that are far away, the lens becomes flatter, allowing the eye to bend light rays less and bring the image into focus. This adjustment in the shape or size of the lens is necessary for proper vision at different distances.Rate this question:
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- 33.
When the eyeball is too deep and lens is unable to flatten enough for crisp focus:
- A.
Myopia
- B.
Hyperopia
- C.
Presbyopia
- D.
Astigmastism
- E.
Strabismus
Correct Answer
A. MyopiaExplanation
Myopia, also known as nearsightedness, occurs when the eyeball is too long or the cornea is too curved. This causes light to focus in front of the retina instead of directly on it, resulting in blurred vision when looking at distant objects. The lens is unable to flatten enough to compensate for the elongated eyeball, leading to difficulty in achieving crisp focus.Rate this question:
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