1
Q
Which of the following correctly traces a homeostatic reflex pathway?
A
Receptor → Control/Integration center → Effector
This pathway illustrates the sequence of events in a reflex action.
2
Q
The CNS includes which structures?
A
- Brain and spinal cord
- Spinal nerves and cranial nerves
The CNS is responsible for processing and transmitting information.
3
Q
Which part of the nervous system controls voluntary muscle movement?
A
Somatic division
The somatic division is responsible for voluntary control of body movements.
4
Q
Which type of neuroglia forms the myelin sheath in the CNS?
A
Oligodendrocytes
Oligodendrocytes are specialized cells that insulate axons in the central nervous system.
5
Q
In the PNS, myelin is produced by:
A
Schwann cells
Schwann cells are essential for myelination of peripheral nerves.
6
Q
The gaps between Schwann cells along a myelinated axon are called:
A
Nodes of Ranvier
These nodes facilitate rapid conduction of nerve impulses.
7
Q
A cluster of neuron cell bodies in the PNS is called a:
A
Ganglion
Ganglia serve as relay points for signals in the peripheral nervous system.
8
Q
Which classification describes a neuron with a single process that splits into peripheral and central branches?
A
Unipolar
Unipolar neurons are typically sensory neurons.
9
Q
A motor neuron is functionally classified as:
A
Efferent
Efferent neurons transmit signals away from the central nervous system.
10
Q
Which connective tissue surrounds a fascicle of nerve fibers?
A
Perineurium
The perineurium protects and supports bundles of nerve fibers.
11
Q
What kind of channel opens in response to a specific chemical, like a neurotransmitter?
A
Ligand-gated
Ligand-gated channels are crucial for synaptic transmission.
12
Q
During the depolarization phase of an action potential, which channels are open?
A
Voltage-gated Na⁺
These channels allow sodium ions to enter the neuron, causing depolarization.
13
Q
The resting membrane potential of a neuron is approximately:
A
–70 mV
This value represents the electrical charge difference across the neuron’s membrane at rest.
14
Q
What happens during repolarization?
A
K⁺ leaves the cell
Repolarization restores the negative membrane potential after depolarization.
15
Q
The absolute refractory period ensures:
A
Unidirectional impulse flow
This period prevents the neuron from firing again immediately.
16
Q
Which of the following increases the speed of impulse conduction?
A
Myelination
Myelination allows faster transmission of electrical signals along the axon.
17
Q
Saltatory conduction occurs in:
A
Myelinated axons
This conduction method is more efficient than continuous conduction.
18
Q
At a chemical synapse, neurotransmitters are released from:
A
Axon terminal of presynaptic neuron
This release is crucial for communication between neurons.
19
Q
Temporal summation refers to:
A
One neuron sending rapid signals in succession
This process can lead to a stronger postsynaptic response.
20
Q
Which of the following is NOT a function of muscle tissue?
A
Vitamin D synthesis
Muscle tissue is primarily involved in movement, posture, and heat production.
21
Q
Which muscle type is voluntary and striated?
A
Skeletal
Skeletal muscle is under conscious control and has a striated appearance.
22
Q
Which muscle type has intercalated discs?
A
Cardiac
Intercalated discs facilitate synchronized contraction of cardiac muscle.
23
Q
Which connective-tissue covering surrounds a whole skeletal muscle?
A
Epimysium
The epimysium encases the entire muscle, providing structure and support.
24
Q
The functional unit of a myofibril is the:
A
Sarcomere
Sarcomeres are the repeating units that contract to produce muscle movement.
25
Thick filaments are composed primarily of:
Myosin
## Footnote
Myosin is essential for muscle contraction through cross-bridge cycling.
26
Which regulatory protein blocks **myosin-binding sites** on actin?
Tropomyosin
## Footnote
Tropomyosin regulates muscle contraction by preventing myosin from binding to actin.
27
During muscle contraction, the **H zone**:
Narrows or disappears
## Footnote
The H zone is the region of the sarcomere that shortens during contraction.
28
Which structure conducts **action potentials** deep into the muscle fiber?
T-tubule
## Footnote
T-tubules facilitate the transmission of action potentials to the interior of the muscle cell.
29
Calcium ions bind to _______ to expose active sites on actin.
Troponin
## Footnote
This binding is crucial for initiating muscle contraction.
30
According to the **sliding-filament theory**, muscle contraction occurs when:
Filaments slide past each other
## Footnote
This theory explains how muscle fibers shorten during contraction.
31
The **latent period** in a muscle twitch represents:
Excitation-contraction coupling
## Footnote
This period is the time between stimulus and the onset of muscle contraction.
32
Which describes **wave summation**?
Increased force from rapid stimulation
## Footnote
Wave summation results from successive stimuli that increase muscle tension.
33
Which of the following describes **treppe**?
Progressive increase in strength after repeated stimuli
## Footnote
Treppe occurs when a muscle is stimulated repeatedly, leading to increased contraction strength.
34
Which of the following energy sources provides **ATP** for the first few seconds of contraction?
Creatine phosphate
## Footnote
Creatine phosphate quickly regenerates ATP during the initial phase of muscle activity.
35
Anaerobic respiration produces:
Lactic acid and small amounts of ATP
## Footnote
This process occurs when oxygen is limited during intense exercise.
36
During prolonged exercise, which pathway predominates?
Aerobic
## Footnote
Aerobic respiration is more efficient for sustained energy production.
37
Which best defines **oxygen debt**?
Oxygen required to restore metabolic conditions post-exercise
## Footnote
Oxygen debt refers to the amount of oxygen needed to recover from exercise.
38
Muscle fatigue occurs when:
ATP production fails to meet demand
## Footnote
Fatigue results from an imbalance between ATP supply and muscle activity.
39
Which type of muscle fiber is most resistant to **fatigue**?
Slow oxidative
## Footnote
Slow oxidative fibers are adapted for endurance activities.
40
Single-unit smooth muscle is typically found in:
Walls of digestive tract
## Footnote
Single-unit smooth muscle contracts as a coordinated unit.
41
Multi-unit smooth muscle is characterized by:
Independent fiber contraction
## Footnote
Multi-unit smooth muscle fibers operate independently of each other.
42
Which of these correctly pairs a **connective-tissue wrapping** to its content?
Endomysium → Muscle fiber
## Footnote
The endomysium surrounds individual muscle fibers.
43
A **motor unit** consists of:
A motor neuron and all muscle fibers it controls
## Footnote
Motor units are essential for muscle contraction and coordination.
44
Which statement is true about the **all-or-none principle**?
Individual fibers contract fully or not at all
## Footnote
This principle ensures consistent contraction of muscle fibers.
45
In a resting muscle fiber, most **Ca²⁺** is stored in the:
Sarcoplasmic reticulum
## Footnote
The sarcoplasmic reticulum regulates calcium levels for muscle contraction.
46
Myofibrils are composed of:
Bundles of actin and myosin filaments
## Footnote
Myofibrils are the contractile elements of muscle fibers.
47
Which is TRUE about **smooth muscle**?
Lacks T-tubules and sarcomeres
## Footnote
Smooth muscle has a different structure compared to skeletal and cardiac muscle.
48
Cardiac muscle fibers are joined by **gap junctions** to allow ion flow between cells.
Gap junctions
## Footnote
Gap junctions facilitate electrical coupling in cardiac muscle.
49
Which statement best differentiates **spatial from temporal summation**?
Spatial = multiple neurons firing simultaneously; Temporal = rapid firing of one neuron
## Footnote
This distinction is important for understanding synaptic integration.
50
Which of the following would increase the **propagation speed** of a nerve impulse?
Increased axon diameter and myelination
## Footnote
Larger diameter and myelination enhance the speed of nerve signal transmission.
51
List the **three major types of muscle tissue** and one unique feature of each.
* Skeletal: Striated and voluntary
* Cardiac: Striated and involuntary, intercalated discs
* Smooth: Non-striated and involuntary
## Footnote
Each muscle type has distinct structural and functional characteristics.
52
Describe the **“all-or-none” principle** and its significance in muscle contraction.
Each muscle fiber contracts fully or not at all; ensures consistent contraction without partial activation
## Footnote
This principle is crucial for effective muscle function.
53
Explain the difference between **graded (local)** and **action potentials**.
* Graded potentials: Local, decremental changes
* Action potentials: All-or-none, propagated along the axon
## Footnote
Understanding these differences is key to grasping neuronal signaling.
54
List and describe the **three types of gated ion channels** in neurons.
* Ligand-gated: Open with chemical
* Voltage-gated: Open with membrane potential change
* Mechanically-gated: Open with pressure or stretch
## Footnote
These channels are essential for neuronal excitability and signaling.
55
What happens during the **absolute and relative refractory periods**?
* Absolute: No new AP can start
* Relative: Stronger stimulus required to fire again
## Footnote
These periods regulate the timing of action potentials.
56
Define **saltatory conduction** and state its advantage over continuous conduction.
Saltatory conduction = impulse “jumps” node to node on myelinated axons; faster than continuous conduction
## Footnote
This mechanism increases the speed of nerve impulse transmission.
57
Compare and contrast **aerobic and anaerobic ATP production** in muscle cells.
* Aerobic: Uses oxygen, high ATP yield, slower
* Anaerobic: No oxygen, quick ATP burst, lactic acid by-product
## Footnote
Understanding these pathways is crucial for exercise physiology.
58
What is **oxygen debt** and how is it repaid after exercise?
Oxygen debt = extra O₂ needed to restore ATP, CP, and remove lactic acid after exercise
## Footnote
This concept is important for understanding recovery after physical activity.
59
Describe the role of **Ca²⁺ and ATP** in muscle contraction.
* Ca²⁺ binds to troponin to expose binding sites
* ATP detaches cross-bridges and powers myosin head movement
## Footnote
Both are essential for the contraction process in muscle fibers.
60
What is the functional difference between **single-unit and multi-unit smooth muscle**?
* Single-unit: Cells linked by gap junctions (contract as a sheet)
* Multi-unit: Independent fibers contract separately
## Footnote
This distinction affects how these muscle types function in the body.
61
Describe the sequence of events at a **chemical synapse** from arrival of an action potential to postsynaptic potential generation.
* AP arrives → Ca²⁺ enters axon terminal → vesicles release neurotransmitter → NT binds to postsynaptic receptors → graded potential generated
## Footnote
This process is critical for neuronal communication.
62
Name the **connective-tissue layers** of a skeletal muscle from deepest to most superficial.
* Endomysium → Perimysium → Epimysium
## Footnote
These layers provide structure and support to muscle fibers.
63
What is **direct phosphorylation**?
A method of regenerating ATP using creatine phosphate
## Footnote
It provides a rapid source of energy for muscle contraction.
64
What is **oxidative phosphorylation**?
A process that produces ATP through the electron transport chain and chemiosmosis
## Footnote
It occurs in the mitochondria and requires oxygen.
65
Which statement best explains why **lactic acid** builds up in fatigued muscle?
Lack of O₂ forces pyruvate into anaerobic pathways
## Footnote
This leads to the production of lactic acid during intense exercise.
66
Which connective-tissue wrapping surrounds each individual **muscle fiber**?
Endomysium
## Footnote
It provides support and protection to individual muscle fibers.
67
The latent period of a muscle twitch represents:
Interval between stimulus and tension development as excitation–contraction coupling occurs
## Footnote
This phase is crucial for the initiation of muscle contraction.
68
If a second stimulus arrives before the muscle has fully relaxed, the result is:
Wave summation
## Footnote
This leads to increased muscle tension due to successive stimuli.
69
A muscle producing smooth, sustained contractions is demonstrating:
Tetanus
## Footnote
This occurs when muscle fibers are stimulated at a high frequency.
70
Which process directly restores ATP during the first few seconds of activity?
Direct phosphorylation of ADP by creatine phosphate
## Footnote
This is the fastest way to regenerate ATP in muscles.
71
Which is a characteristic of **smooth muscle** but not **skeletal muscle**?
Gap junctions allowing synchronized contraction
## Footnote
This feature enables coordinated contractions in smooth muscle.
72
Which structure in **cardiac muscle** allows rapid electrical communication between cells?
Gap junctions within intercalated discs
## Footnote
These structures facilitate synchronized heart contractions.
73
Which statement best explains why **ATP** is necessary for muscle relaxation?
It detaches myosin from actin and powers Ca²⁺ reuptake into the SR
## Footnote
ATP is crucial for both contraction and relaxation processes.
74
During **rigor mortis**, muscles remain stiff because:
ATP is unavailable to break cross-bridges
## Footnote
This condition occurs after death due to lack of ATP production.
75
Which factor primarily determines the **force of a muscle contraction**?
Number of active cross-bridges (motor units recruited)
## Footnote
More cross-bridges lead to stronger contractions.
76
When a neuron's membrane potential moves from –70 mV to –90 mV, this is called:
Hyperpolarization
## Footnote
This makes the neuron less likely to fire an action potential.
77
Which event restores resting potential after **depolarization**?
K⁺ efflux through voltage-gated channels
## Footnote
This process helps return the membrane potential to its resting state.
78
If extracellular potassium levels rise abnormally high, neurons become:
Less excitable (hyperpolarized)
## Footnote
High potassium levels can inhibit action potentials.
79
Neurotransmitter release at the axon terminal is triggered by:
Influx of Ca²⁺
## Footnote
Calcium ions play a crucial role in the exocytosis of neurotransmitters.
80
The region where neurotransmitters cross to the next neuron is called the:
Synaptic cleft
## Footnote
This space is essential for communication between neurons.
81
Which event best explains the **refractory period** of a neuron?
Na⁺ channels are inactivated and cannot reopen immediately
## Footnote
This period ensures unidirectional propagation of action potentials.
82
Which of the following would increase **conduction speed** the most?
Myelination and a large axon diameter
## Footnote
These factors enhance the speed of nerve impulse transmission.
83
What is the primary function of the **nodes of Ranvier**?
Provide sites for ion exchange during impulse transmission
## Footnote
They facilitate saltatory conduction in myelinated axons.
84
Which part of the nervous system directly controls **skeletal-muscle movement**?
Somatic motor neurons
## Footnote
These neurons are responsible for voluntary muscle control.
85
Which connective-tissue layer of a nerve encloses an entire nerve (all fascicles)?
Epineurium
## Footnote
It provides protection and structural integrity to the nerve.
86
Which event occurs at the **neuromuscular junction** immediately after acetylcholine binds to receptors?
Depolarization of the sarcolemma
## Footnote
This initiates the process of muscle contraction.
87
If acetylcholinesterase were inhibited, the result would be:
Continuous muscle stimulation and spasm
## Footnote
This occurs due to the accumulation of acetylcholine.
88
Which situation would lead to the fastest **muscle recovery**?
Maintaining high blood flow and oxygen supply
## Footnote
Adequate oxygen helps clear lactic acid and replenish energy stores.
89
The “**recruitment**” of motor units allows a muscle to:
Produce a stronger contraction by activating additional fibers
## Footnote
This mechanism enables graded muscle responses.
90
A muscle’s ability to stretch without damage refers to:
Extensibility
## Footnote
This property is essential for normal muscle function.
91
Which of the following statements about **muscle tone** is TRUE?
It results from partial, continuous activation of some motor units
## Footnote
Muscle tone is important for posture and readiness.
92
Explain why **myelinated fibers** conduct impulses faster than unmyelinated ones.
Action potentials 'jump' between nodes of Ranvier, reducing ion exchange
## Footnote
This process, known as saltatory conduction, speeds up signal transmission.
93
Describe the sequence of events that occur at a **chemical synapse** when an action potential reaches the axon terminal.
Action potential arrives → voltage-gated Ca²⁺ channels open → Ca²⁺ enters → vesicles release neurotransmitter → neurotransmitter binds to receptors
## Footnote
This sequence is crucial for neurotransmission.
94
Compare the roles of **Na⁺** and **K⁺ channels** during depolarization and repolarization of an action potential.
Na⁺ channels open first for depolarization; K⁺ channels open later to repolarize
## Footnote
This sequence is essential for the action potential's shape.
95
Explain how **temporal summation** can lead a neuron to reach threshold.
Rapid, repeated stimulation from one presynaptic neuron causes EPSPs to build up
## Footnote
This accumulation can trigger an action potential.
96
Define **recruitment** and explain how it contributes to graded muscle contractions.
Recruitment = activation of additional motor units as stimulus strength increases
## Footnote
This allows muscles to adjust force output based on demand.
97
Why is **ATP** required both for muscle contraction and relaxation?
ATP attaches to myosin to release actin and powers myosin-head pivoting
## Footnote
It is essential for both the contraction and relaxation phases.
98
Describe how **oxygen debt** is repaid after intense exercise.
Oxygen restores ATP and creatine phosphate, converts lactic acid back to pyruvate
## Footnote
This process helps restore normal metabolic function.
99
What causes **rigor mortis** and why does it eventually subside?
Rigor mortis results when ATP is depleted; it subsides as cellular proteins degrade
## Footnote
This breakdown leads to the relaxation of muscles.
100
Explain how **calcium ions** regulate the contraction cycle.
Ca²⁺ binds to troponin, shifting tropomyosin off actin’s binding sites
## Footnote
This allows cross-bridges to form between actin and myosin.
101
Distinguish between **single-unit** and **multi-unit smooth muscle** in terms of structure and function.
Single-unit = sheets linked by gap junctions; multi-unit = independent fibers for precise control
## Footnote
This difference affects how these muscle types contract.
102
What would happen to muscle contraction if **acetylcholinesterase** were blocked? Explain why.
Continuous stimulation and spastic paralysis occur due to acetylcholine accumulation
## Footnote
This prevents muscle relaxation and leads to sustained contraction.
103
List the **connective-tissue coverings** of a skeletal muscle from deepest to most superficial and state what each surrounds.
* Endomysium: surrounds each muscle fiber
* Perimysium: surrounds a fascicle
* Epimysium: surrounds entire muscle
## Footnote
These layers provide structure and support to muscle tissue.
104
What is the **total muscle length**?
The length of muscle fibers when fully extended
## Footnote
This measurement is important for understanding muscle function and biomechanics.
105
What is the significance of **lactic acid** in muscle activity?
It accumulates during anaerobic metabolism, contributing to muscle fatigue
## Footnote
Lactic acid is a byproduct of glycolysis when oxygen levels are low.
106
Which best explains the **stair-step (treppe) phenomenon**?
* Repeated stimuli increase Ca²⁺ availability before muscle fully relaxes
* Recruitment of new motor units each time
* ATP depletion between stimuli
* Random summation of twitches
## Footnote
This phenomenon describes the increased force of contraction with repeated stimulation.
107
Which type of muscle fiber would dominate in a **weight-lifter’s quadriceps**?
* Fast glycolytic
## Footnote
These fibers are suited for short bursts of high-intensity activity.
108
A drug that blocks **Ca²⁺ reuptake** into the SR would cause:
* Prolonged contraction (incomplete relaxation)
## Footnote
This is due to sustained calcium presence in the cytoplasm.
109
Which factor contributes most to **muscle fatigue** during intense activity?
* Accumulation of inorganic phosphate and lactic acid
## Footnote
Other factors include depletion of energy substrates and ionic imbalances.
110
If the **axon hillock** is damaged, what is directly impaired?
* Initiation of action potentials
## Footnote
The axon hillock is crucial for generating action potentials in neurons.
111
In **saltatory conduction**, action potentials occur only at:
* Nodes of Ranvier
## Footnote
This allows for faster transmission of electrical signals along myelinated axons.
112
Which structural feature ensures **unidirectional flow** of information in a neuron?
* Axon hillock orientation and refractory periods
## Footnote
These features prevent backward propagation of action potentials.
113
The effect of increasing **extracellular K⁺** slightly is:
* Easier depolarization (cell becomes more excitable)
## Footnote
Elevated potassium levels can lower the threshold for action potentials.
114
Which is the best example of an **isometric contraction**?
* Holding a plank position
## Footnote
Isometric contractions occur when muscle length does not change despite tension.
115
When acetylcholine binds to receptors on the **motor end plate**:
* Ligand-gated Na⁺ channels open, depolarizing the sarcolemma
## Footnote
This initiates the process of muscle contraction.
116
A single motor neuron stimulating multiple fibers illustrates:
* A motor unit
## Footnote
Motor units are fundamental for muscle contraction and force generation.
117
Which statement about **smooth muscle** is TRUE?
* It contracts slowly and can maintain tone without fatigue
## Footnote
Smooth muscle is found in various organs and is essential for involuntary movements.
118
Which outcome occurs if **extracellular Ca²⁺ levels** fall drastically?
* Weaker synaptic transmission and muscle contraction
## Footnote
Calcium is crucial for neurotransmitter release and muscle contraction.
119
If a patient’s **patellar reflex** is absent, this most likely indicates:
* Damage to spinal segments L2–L4
## Footnote
The patellar reflex tests the integrity of specific spinal cord segments.
120
A muscle with high **myoglobin content** and many mitochondria is best suited for:
* Endurance and fatigue resistance
## Footnote
These characteristics are typical of slow-twitch muscle fibers.
121
Which event would increase the duration of the **refractory period** in neurons?
* Slower Na⁺ channel recovery
## Footnote
This affects the ability of neurons to fire again after an action potential.
122
Explain how **demyelination** affects action potential conduction speed and reliability.
It removes insulation, forcing continuous conduction instead of saltatory; impulses slow and may fail entirely
## Footnote
This can lead to neurological deficits.
123
Describe the metabolic pathway used for **ATP production** during a 400 m sprint and why fatigue set in.
Used anaerobic glycolysis—rapid ATP with lactic-acid by-product; fatigue occurs as pH drops and ATP yield is low
## Footnote
This pathway is efficient for short bursts of high-intensity exercise.
124
How does a local anesthetic that blocks **voltage-gated Na⁺ channels** prevent pain sensation?
It prevents depolarization and action-potential generation, so pain impulses never reach the CNS
## Footnote
This is a common mechanism for local anesthetics.
125
How can a neuron convert a **weak stimulus** into a stronger perceived signal?
* Stronger stimuli increase frequency of firing (temporal summation)
* Recruit more neurons (spatial summation)
## Footnote
This enhances the overall signal perceived by the brain.
126
Describe the **short-term and long-term muscular adaptations** that occur with strength training.
* Short-term: improved neural recruitment and coordination
* Long-term: hypertrophy, more myofibrils, mitochondria, and glycogen stores
## Footnote
These adaptations enhance muscle performance and endurance.
127
Why does **cardiac muscle** not experience tetanus, and what would happen if it did?
* Cardiac cells have long refractory periods; tetanus would stop rhythmic pumping—fatal if it occurred
## Footnote
This is crucial for maintaining effective heart function.
128
Compare the role of **Ca²⁺** in skeletal-muscle contraction versus neurotransmitter release.
* In muscle, Ca²⁺ binds troponin to uncover actin sites
* At synapses, Ca²⁺ triggers vesicle fusion and neurotransmitter release
## Footnote
Calcium plays a vital role in both processes but in different contexts.
129
During **hyperkalemia**, explain how resting membrane potential and neuron excitability change.
* Extra K⁺ makes the resting potential less negative (depolarized), making neurons hyper-excitable or unable to repolarize
## Footnote
This can lead to abnormal neuronal firing.
130
What are the effects on **skeletal-muscle contraction and relaxation** if a person inhales a toxin that blocks ATP production?
* Without ATP, myosin can’t detach (rigor), Ca²⁺ pumps stop, and muscles stay contracted—no relaxation or sustained activity
## Footnote
This can lead to muscle stiffness and inability to relax.
131
Explain how the **length–tension relationship** affects the strength of a muscle contraction.
* Optimal overlap between actin and myosin produces maximal tension; too stretched or too compressed reduces cross-bridge formation
## Footnote
This relationship is crucial for effective muscle function.
132
Describe how the **autonomic nervous system** responds to a sudden threat and then returns the body to normal.
* Sympathetic division triggers “fight-or-flight”: ↑ heart rate, dilation, glucose release; parasympathetic later restores rest-and-digest balance
## Footnote
This dual response is essential for survival.
133
How does a **reflex arc** bypass the brain for rapid response?
* It routes impulses through the spinal cord instead of the brain, giving instant protective responses that prevent injury
## Footnote
This design enhances survival by allowing quick reactions.
