Cranial Nerves and Sensory Physiology Quiz

The nervous system is organized hierarchically, with distinct levels of complexity: Central Nervous System (CNS) and Peripheral Nervous System (PNS).

A nerve is a bundle of axons, much like a cable carrying electrical signals.

The sympathetic nervous system prepares the body for 'fight or flight' by increasing heart rate, dilating pupils, and diverting blood to muscles.

The parasympathetic nervous system promotes 'rest and digest' by slowing heart rate, constricting pupils, and enhancing digestion.

Cranial nerves emerge from the brain and brainstem, connecting to parts of the head and neck.

Spinal nerves branch off from the spinal cord, connecting to the rest of the body.

Cranial nerves can carry sensory information (from the body to the brain), motor commands (from the brain to the body), or both.

Olfactory nerve (I) is responsible for our sense of smell.

The parasympathetic nervous system is responsible for "rest and digest" functions like slowing heart rate, stimulating digestion, and constricting pupils.

The parasympathetic nervous system is part of the autonomic nervous system, which controls involuntary bodily functions.

Cranial nerves are a set of 12 nerves that connect the brain to different parts of the head and neck.

The sympathetic nervous system is responsible for "fight or flight" responses like increasing heart rate, diverting blood to muscles, and dilating pupils.

Sensory receptors are specialized cells that detect stimuli in our environment, converting them into signals that can be interpreted by the nervous system.

Receptor potential is the graded potential generated in a sensory receptor in response to a stimulus. Its amplitude is proportional to the stimulus intensity.

Frequency coding is a way of encoding stimulus intensity by changing the frequency of action potentials in a single neuron. A stronger stimulus leads to more frequent firing.

Population coding is a method of encoding stimulus intensity by recruiting more neurons to fire. As the stimulus strengthens, more neurons become involved.

Tonic receptors are sensory receptors that adapt slowly or not at all to continuous stimulation. They continue to send signals to the brain about the stimulus.

Phasic receptors are sensory receptors that quickly adapt to a sustained stimulus, reducing their firing rate even with continued stimulation.

Adaptation is the process where sensory receptors become less responsive to a sustained stimulus. This allows us to focus on changes in our environment.

Sensory receptors convert different types of stimuli (light, sound, pressure) into electrical signals that the nervous system can understand. This process is called transduction.

The initial segment of a myelinated sensory axon where the action potential is generated.

A graded potential (GP) is similar to an excitatory postsynaptic potential (EPSP) in that it can vary in amplitude depending on the stimulus strength. A larger stimulus results in a larger GP. Unlike EPSPs, GPs are not propagated actively like action potentials and don't make the membrane refractory.

In the case of somatosensory mechanoreceptors, the GP arises from the direct impact of mechanical stimuli on stretch-sensitive channels. These channels are non-selective, allowing both sodium (Na+) and potassium (K+) ions to pass through. However, due to the greater driving force for Na+, the net result is depolarization.

The GP in nociceptors, photoreceptors, and chemoreceptors involves separate cells or G-protein-coupled mechanisms that indirectly influence ion channels. The initial stimulus triggers a cascade of events within these separate cells, eventually leading to the opening or closing of ion channels and the generation of a GP.

The Receptor Potential is a type of GP that occurs in specialized sensory receptor cells. It represents the initial response of a receptor cell to a stimulus.

Specialized sensory receptor cells like auditory and photoreceptor cells have a separate cell ending. The initial stimulus triggers a series of events within these specialized cells that ultimately lead to the generation of a GP.

In specialized sensory receptor cells like auditory and photoreceptors, the GP is generated within the separate cell ending. This implies that the sensory neuron itself doesn't directly receive the initial stimulus, but is influenced by the specialized cell's response.

The Receptor Potential is a graded potential, which means its strength is proportional to the intensity of the stimulus.

Sensory receptors are specialized cells or structures that detect changes in the internal or external environment. They convert these changes into electrical signals that the nervous system can interpret.

Muscle stretch receptors sense the length of muscles, while joint proprioceptors detect the angle of joints. This information helps the CNS maintain posture and balance.

Phasic receptors quickly adapt to a constant stimulus, becoming less responsive over time. Think of putting on clothes: you quickly forget you're wearing them. When you take them off, you notice the change (the 'off response').

Nerve fibers can be classified by their conduction velocity, size, and myelination status. This classification uses letter designations (A, B, C) and Roman numerals.

Group A nerve fibers are the fastest, largest, and myelinated. They are responsible for conveying signals related to touch, pressure, temperature, and motor commands.

Group B fibers are smaller, slower, and myelinated. They transmit signals related to autonomic functions, such as regulating heart rate and digestion.

Group C fibers are the smallest, slowest, and unmyelinated. They carry pain sensations as well as some autonomic signals.

A classification system for peripheral nerve fibers using Roman numerals (I-IV) based on their diameter, which corresponds to their conduction velocity. Primarily used for sensory axons.

This system classifies nerve fibers using letters: Aα, Aβ, Aγ, Aδ and B. This scheme is used for both sensory and motor axons.

Sensory nerve fibers that are the largest and fastest, responsible for proprioception (muscle position) and touch.

The main motor neurons that trigger muscle contraction.

Sensory fibers for touch, pressure, and some temperature.

Motor neurons that control the intrafusal muscle fibers in muscle spindles, contributing to proprioception.

Sensory fibers for temperature, pain, and some touch. They are smaller and slower than Aβ fibers.

Autonomic nerve fibers that carry signals for the parasympathetic nervous system.

Smaller, unmyelinated nerve fibers involved in pain, temperature, and some autonomic functions.

The speed at which a nerve impulse travels along a nerve fiber.