Neuro: sensory Receptors Quiz

Synapse

• Synapse is the point of connection between a nerve cell and another cell
• It's a specialized junction for nerve cell (neuron) communication with target cells
• Target cells can be nerves, muscles, or glands

Types of Synapses

• Electrical Synapses: Found in vertebrates, relatively rare

• Membranes of the two cells are in close contact

• Enable rapid and reliable transmission of nerve impulses (action potentials)

• Chemical Synapses: More complex

• Presynaptic and postsynaptic cells are separated by a gap (synaptic cleft)

• Prevents simple electrical transmission of action potentials

• Transmission is accomplished by neurotransmitters

Neurotransmitter Action

• Presynaptic nerve terminal cytoplasm is packed with synaptic vesicles holding neurotransmitters
• When an action potential arrives, it stimulates voltage-gated calcium channels opening in the terminal membrane
• Calcium ions flood the cell and trigger synaptic vesicles to release their contents into the synaptic cleft
• Released neurotransmitters diffuse across the cleft to interact with specialized protein receptors on the postsynaptic membrane
• Neurotransmitter binding produces a change in the receptor's shape, opening an intrinsic ion channel
• At nerve-muscle synapses and some nerve-nerve synapses, receptors act as ion channels.

Synaptic Transmission Steps

• Step 1: Action potential reaches axon bulb, opens calcium channels, and calcium flows in
• Step 2: Calcium inflow triggers synaptic vesicles to move toward and fuse with the presynaptic membrane
• Step 3: Neurotransmitters are released into the synaptic cleft through exocytosis
• Step 4: Released neurotransmitters travel across the synaptic cleft and attach to receptors on the postsynaptic membrane
• Step 5: Neurotransmitter binding causes ion channels to open and depolarize/hyperpolarize the postsynaptic membrane
• Step 6: Enzymes break down or reabsorb the neurotransmitters to prevent prolonged stimulation/inhibition.

Seven Processes in Neurotransmitter Action

• Neurotransmitter synthesis from precursors enzymes
• Storage of neurotransmitters in vesicles
• Leakage of neurotransmitter from vesicles (destroyed by enzymes)
• Vesicle fusion with presynaptic membrane; release of neurotransmitter into synapse
• Neurotransmitter binding with auto receptors (inhibits release) and postsynaptic receptors
• Neurotransmitter deactivation either via reuptake or enzymatic degradation

Not All Synaptic Transmission is Excitatory

• Some neurotransmitters act as inhibitory transmitters, making the postsynaptic cell less excitable and less likely to generate an action potential.
• Often act on receptors that function as channels for chloride or potassium ions, typically hyperpolarizing the postsynaptic cell.

Excitatory and Inhibitory Neurotransmitter Actions

• EPSP (Excitatory Postsynaptic Potential): Action potential arriving at the presynaptic terminal results in a flood of positively charged sodium ions into the postsynaptic cell, making the membrane potential less negative.
• IPSP (Inhibitory Postsynaptic Potential): Neurotransmitters bind to receptors acting as channels for chloride or potassium ions, making the membrane potential more negative.

Details of a Synapse

• Diagram of the pre-synaptic terminal, synaptic cleft, synaptic vesicle, post-synaptic element and related components.

Nerve Communication

• Illustration of neurotransmitters being released into the synaptic cleft, degraded, and reuptaken.

Synaptic Transmission

• Detailed step-by-step description illustrating the process.

Types of Neurotransmitters

• Table classifying neurotransmitters with their type and function/effect, with examples.

Neural Circuits

• Neural circuits, both anatomical and functional, for example the myotatic reflex (knee-jerk reflex).
• The sensory and motor components for this specific circuit

Divergence and Convergence

• Divergence is the spread of information from one neuron to several other neurons; e.g., visual input
• Convergence is the synapsing of several neurons on a single neuron; e.g. coordinating multiple stimuli to create a single response

Serial Processing

• Information relayed in a stepwise fashion from one neuron or neuronal pool to the next.
• Example: sensory information being relayed from one part of the brain to another
• Serial processing is vital for sending data from one area of the brain to another

Parallel Processing

• Several neurons or neuronal pools process the same information simultaneously

Neural Circuit Types

• Includes descriptions of sensory and motor pathways, integration, wakefulness and sleep, learning and memory

Levels and Pathways of Sensation

• Overview of pathways for conveying sensations from the body to the brain.

Sensation

• Conscious or unconscious awareness of internal or external stimuli
• Sensations differ depending on receptor stimulation and the destination of impulses in CNS

Perception

• The conscious awareness and interpretation of a sensation
• Includes localization and identification of the sensation, and storage of memories for later use.

Sensory Modalities

• Properties of sensory modalities
• Different types of sensory modalities like touch, pain, temperature, vibration, hearing, vision and special senses.

Receptors

• Structural classification of sensory receptors (free nerve endings, encapsulated nerve endings and separate cells),
• Type of stimuli detected by types of sensory receptors (e.g., mechanoreceptors detect physical or mechanical stress, chemoreceptors detect specific chemicals).

Touch

• Types of touch and receptors involved:
  • Crude touch
  • Discriminative touch

Receptors

• Specific types of sensory receptors in skin: Meissner corpuscles, hair root plexuses, Merkel discs, Ruffini corpuscles.

Sensory Receptor Structures and Types

• General sensory receptors and special sensory receptors, along with examples of their structures and locations

Generator Potentials

• Generator potential is a type of graded potential, produced by free nerve endings, encapsulated nerve endings and olfactory receptors
• Conversion of stimulus energy into electrical energy

Receptor Potential

• Type of graded potential, produced by sensory receptors of vision, hearing, equilibrium or taste.
• Generation converts stimulus energy into electrical energy for transmission of stimuli in the peripheral nervous systems.

Types of Sensory Receptors

• Exteroceptors, interoceptors, proprioceptors. (Example placement on body for each type).

Adaptation

• Most sensory receptors exhibit adaptation—the tendency for the generator/receptor potential to decrease in amplitude during a maintained constant stimulus.
• Some receptors adapt quickly, while others adapt slowly.

Tonic Receptors and Phasic Receptors

• Tonic receptors adapt slowly and continuously, while Phasic receptors adapt rapidly and stop responding to ongoing constant stimuli, but can detect changes in stimulus intensity or rate.

Pain

• Fast and Slow pain; locations within the body and how their sensory signals ascend through associated tracts of the nervous system.
• How different types of stimuli lead to pain mechanisms are differentiated within the body

Visceral pain

• Description; differences with somatic pain; examples.

Pain Threshold and Tolerance

• Pain threshold
• Pain Tolerance; e.g., how much pain a person can endure.

Test your knowledge about sensory receptors, including exteroceptors, proprioceptors, and various receptor types responsible for detecting sensations such as pain and temperature. This quiz delves into the functions and characteristics of sensory receptors in the human body.