BIOL 252 Human Anatomy & Physiology
II w/Lab Revised Test For Approved
Questions And Certified Answers For
Garanteed Grade
What are the phases of an action potential?
Resting, depolarization, repolarization, hyperpolarization, and return to resting
membrane potential.
What triggers the release of neurotransmitters at a chemical synapse?
The influx of Ca²⁺ ions through voltage-gated channels.
What are EPSPs and IPSPs?
EPSPs (excitatory postsynaptic potentials) depolarize the membrane; IPSPs (inhibitory
postsynaptic potentials) hyperpolarize it.
What is the resting membrane potential (RMP) typically?
-70 mV, maintained by Na⁺/K⁺ pumps and K⁺ leak channels.
What is the role of the sarcomere in muscle contraction?
It is the functional contractile unit of muscle fibers.
What is the structure of a sarcomere?
Contains Z discs, I bands, A bands, H zones, and M lines.
What initiates excitation-contraction coupling in muscle fibers?
An action potential in the motor neuron leading to the release of ACh at the
neuromuscular junction.
What is the function of troponin in muscle contraction?
Binds Ca²⁺ to move tropomyosin and expose myosin-binding sites on actin.
What characterizes cardiac muscle?
Involuntary, striated, branched fibers with intercalated discs and autorhythmic
properties.
What is the purpose of the refractory period in action potentials?
Prevents the generation of another action potential during certain phases.
What are the types of neural circuits?
Diverging, converging, reverberating, and parallel-after-discharge circuits.
What is the role of Schwann cells in the PNS?
Myelinate one axon segment and assist in nerve regeneration.
What does the Central Nervous System (CNS) consist of?
The brain (cerebrum, diencephalon, brainstem, cerebellum) and spinal cord.
What is the function of the Somatic Nervous System (SNS)?
Controls voluntary skeletal muscle movements.
What are the two branches of the Autonomic Nervous System (ANS)?
Sympathetic (fight or flight) and Parasympathetic (rest & digest).
, What is the role of astrocytes in the CNS?
Form the blood-brain barrier, regulate potassium levels, and recycle neurotransmitters.
What is myelin and its function?
A lipid-rich insulating sheath that increases conduction speed of action potentials.
What is the difference between fast and slow axonal transport?
Fast transport (200-400 mm/day) uses microtubules for vesicles and organelles; slow
transport (1-5 mm/day) moves cytoskeletal elements.
What neurotransmitter is primarily excitatory in the CNS?
Glutamate.
What is the function of the enteric nervous system?
Regulates gastrointestinal tract functions like peristalsis and secretion.
What is the significance of the axon hillock?
It is the site where the decision to generate an action potential is made.
What are the main types of muscle fibers?
Skeletal, cardiac, and smooth muscle.
What is the role of neurotransmitter reuptake?
It removes neurotransmitters from the synaptic cleft to terminate the signal.
What is the difference between graded potentials and action potentials?
Graded potentials are decremental and can vary in strength; action potentials are all-or-
none and non-decremental.
What neurotransmitter diffuses across the neuromuscular junction (NMJ)?
Acetylcholine (ACh)
What happens when ACh binds to nicotinic ACh receptors on the sarcolemma?
Ligand-gated Na⁺ channels open, leading to an end plate potential (EPP).
What triggers the generation of an action potential in muscle fibers?
If the end plate potential (EPP) reaches threshold.
What enzyme breaks down ACh after it has activated its receptors?
Acetylcholinesterase (AChE).
What is the role of calcium ions (Ca²⁺) in muscle contraction?
Ca²⁺ binds to troponin C, causing tropomyosin to shift and expose myosin-binding sites
on actin.
What occurs during the power stroke of cross-bridge cycling?
Release of ADP + Pi causes the myosin head to pivot and pull actin toward the M line.
What happens if there is no ATP present during muscle contraction?
Rigor mortis occurs, as myosin cannot detach from actin.
What is the function of SERCA pumps in muscle relaxation?
They pump Ca²⁺ back into the sarcoplasmic reticulum (SR), requiring ATP.
What are the core functions of the nervous system?
Sensory input, integration, motor output, and higher-order functions.
What are the types of receptors involved in sensory input?
Mechanoreceptors, thermoreceptors, nociceptors, chemoreceptors, photoreceptors.
What is the primary role of interneurons?
Integration and decision-making; they make up about 90% of neurons.
What are the two main structural divisions of the nervous system?
II w/Lab Revised Test For Approved
Questions And Certified Answers For
Garanteed Grade
What are the phases of an action potential?
Resting, depolarization, repolarization, hyperpolarization, and return to resting
membrane potential.
What triggers the release of neurotransmitters at a chemical synapse?
The influx of Ca²⁺ ions through voltage-gated channels.
What are EPSPs and IPSPs?
EPSPs (excitatory postsynaptic potentials) depolarize the membrane; IPSPs (inhibitory
postsynaptic potentials) hyperpolarize it.
What is the resting membrane potential (RMP) typically?
-70 mV, maintained by Na⁺/K⁺ pumps and K⁺ leak channels.
What is the role of the sarcomere in muscle contraction?
It is the functional contractile unit of muscle fibers.
What is the structure of a sarcomere?
Contains Z discs, I bands, A bands, H zones, and M lines.
What initiates excitation-contraction coupling in muscle fibers?
An action potential in the motor neuron leading to the release of ACh at the
neuromuscular junction.
What is the function of troponin in muscle contraction?
Binds Ca²⁺ to move tropomyosin and expose myosin-binding sites on actin.
What characterizes cardiac muscle?
Involuntary, striated, branched fibers with intercalated discs and autorhythmic
properties.
What is the purpose of the refractory period in action potentials?
Prevents the generation of another action potential during certain phases.
What are the types of neural circuits?
Diverging, converging, reverberating, and parallel-after-discharge circuits.
What is the role of Schwann cells in the PNS?
Myelinate one axon segment and assist in nerve regeneration.
What does the Central Nervous System (CNS) consist of?
The brain (cerebrum, diencephalon, brainstem, cerebellum) and spinal cord.
What is the function of the Somatic Nervous System (SNS)?
Controls voluntary skeletal muscle movements.
What are the two branches of the Autonomic Nervous System (ANS)?
Sympathetic (fight or flight) and Parasympathetic (rest & digest).
, What is the role of astrocytes in the CNS?
Form the blood-brain barrier, regulate potassium levels, and recycle neurotransmitters.
What is myelin and its function?
A lipid-rich insulating sheath that increases conduction speed of action potentials.
What is the difference between fast and slow axonal transport?
Fast transport (200-400 mm/day) uses microtubules for vesicles and organelles; slow
transport (1-5 mm/day) moves cytoskeletal elements.
What neurotransmitter is primarily excitatory in the CNS?
Glutamate.
What is the function of the enteric nervous system?
Regulates gastrointestinal tract functions like peristalsis and secretion.
What is the significance of the axon hillock?
It is the site where the decision to generate an action potential is made.
What are the main types of muscle fibers?
Skeletal, cardiac, and smooth muscle.
What is the role of neurotransmitter reuptake?
It removes neurotransmitters from the synaptic cleft to terminate the signal.
What is the difference between graded potentials and action potentials?
Graded potentials are decremental and can vary in strength; action potentials are all-or-
none and non-decremental.
What neurotransmitter diffuses across the neuromuscular junction (NMJ)?
Acetylcholine (ACh)
What happens when ACh binds to nicotinic ACh receptors on the sarcolemma?
Ligand-gated Na⁺ channels open, leading to an end plate potential (EPP).
What triggers the generation of an action potential in muscle fibers?
If the end plate potential (EPP) reaches threshold.
What enzyme breaks down ACh after it has activated its receptors?
Acetylcholinesterase (AChE).
What is the role of calcium ions (Ca²⁺) in muscle contraction?
Ca²⁺ binds to troponin C, causing tropomyosin to shift and expose myosin-binding sites
on actin.
What occurs during the power stroke of cross-bridge cycling?
Release of ADP + Pi causes the myosin head to pivot and pull actin toward the M line.
What happens if there is no ATP present during muscle contraction?
Rigor mortis occurs, as myosin cannot detach from actin.
What is the function of SERCA pumps in muscle relaxation?
They pump Ca²⁺ back into the sarcoplasmic reticulum (SR), requiring ATP.
What are the core functions of the nervous system?
Sensory input, integration, motor output, and higher-order functions.
What are the types of receptors involved in sensory input?
Mechanoreceptors, thermoreceptors, nociceptors, chemoreceptors, photoreceptors.
What is the primary role of interneurons?
Integration and decision-making; they make up about 90% of neurons.
What are the two main structural divisions of the nervous system?
