Sensory Receptors: Tonic and Phasic Response

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Questions and Answers

What type of receptor adapting rapidly, but generates an off response on removing the stimulus?

Phasic receptor (correct)

Tonic receptor

Slowly adapting receptor

Rapidly adapting receptor

Which type of receptor maintains information about the stimulus, considering it valuable?

Tonic receptor (correct)

Rapidly adapting receptor

Slowly adapting receptor

Phasic receptor

What is the role of the first-order neuron in the transmission of sensory information?

Relay information from the thalamus to the cerebral cortex

Process information in the cerebral cortex

Transmit sensory information from the periphery to the CNS (correct)

Communicate with reflex networks in the spinal cord

Which receptor type adapts slowly to a stimulus, exemplified by pain?

Tonic receptor Signup and view all the answers

What is the purpose of rapidly adapting receptors?

To allow the body to ignore unimportant information Signup and view all the answers

What is the sequence of transmission of sensory information from the periphery to the CNS?

First-order neuron, Second-order neuron, Third-order neuron Signup and view all the answers

What is the primary function of the stimulus-sensitive channels in separate receptor cells?

To permit net Na+ entry and produce receptor potential Signup and view all the answers

What is the primary role of Ca2+ entry in the afferent neuron?

To trigger exocytosis of neurotransmitters Signup and view all the answers

What is the primary difference between the FASTER process and the SLOWER process?

The location of the sensory receptor in each process Signup and view all the answers

What is the primary function of the voltage-gated Na+ channels in the afferent fiber?

To generate action potentials in the afferent neuron fiber Signup and view all the answers

What is the primary role of the neurotransmitter receptor-channel at the afferent ending?

To open chemically gated receptor-channels Signup and view all the answers

What is the final destination of the action potential in the afferent neuron fiber?

The central nervous system (CNS) Signup and view all the answers

What is the primary function of the receptor on an afferent neuron?

To respond to the stimulus and allow for nonspecific ion channel opening Signup and view all the answers

What type of channel is opened in the sensory receptor when a stimulus is present?

Stimulus-sensitive nonspecific cation channel Signup and view all the answers

What is the sequence of events that leads to the generation of an action potential in an afferent neuron?

Stimulus opens stimulus-sensitive channels, permitting Na+ entry, followed by local current flow and opening of voltage-gated Na+ channels Signup and view all the answers

What is the role of sodium ions in the generation of an action potential in an afferent neuron?

Sodium ions enter the cell, generating a depolarization and contributing to the action potential Signup and view all the answers

What is the result of the receptor potential in specialized afferent endings?

The exocytosis of neurotransmitters, which generates a faster action potential Signup and view all the answers

What percentage of cells in the central nervous system are neurons?

90% Signup and view all the answers

What is the primary function of astrocytes in the central nervous system?

To establish the blood-brain barrier and support neurons in 3D space Signup and view all the answers

Which type of glial cell forms the myelin sheath in the peripheral nervous system?

Schwann cells Signup and view all the answers

What is the primary function of microglia in the central nervous system?

To provide immune defense and scavenge pathogens Signup and view all the answers

What is the function of ependymal cells in the central nervous system?

To form the cerebrospinal fluid and regulate its flow Signup and view all the answers

What is the term for the process by which astrocytes take up neurotransmitters such as GABA and glutamate?

Neurotransmitter reuptake Signup and view all the answers

Where are the cell bodies of afferent neurons located?

In the dorsal root ganglion Signup and view all the answers

What type of neurons carry sensory information from receptors in the skin and other organs?

Afferent neurons Signup and view all the answers

What is the function of the dorsal root ganglion?

To transmit sensory information from the body to the brain Signup and view all the answers

What is the role of the autonomic division?

To regulate involuntary body responses Signup and view all the answers

What is the function of efferent neurons?

To carry motor information from the brain to skeletal muscles Signup and view all the answers

What is the difference between afferent and efferent neurons?

Afferent neurons transmit sensory information, while efferent neurons transmit motor information Signup and view all the answers

Study Notes

Receptor Adaptation

Rapidly adapting receptors respond quickly to a stimulus but adapt quickly, generating an off response when the stimulus is removed. This is useful for detecting changes in stimuli.
Slowly adapting receptors maintain information about the stimulus, signaling its duration and intensity. This is essential for monitoring valuable stimuli, like pain.

Sensory Information Transmission

First-order neurons are the first neurons in the sensory pathway. Their peripheral endings act as sensory receptors, converting stimuli into electrical signals.
Stimulus-sensitive channels in separate receptor cells open in response to a stimulus, leading to a change in membrane potential.
Ca2+ entry in the afferent neuron triggers the release of neurotransmitters.
Voltage-gated Na+ channels in the afferent fiber generate action potentials that propagate along the axon.
Neurotransmitter receptor-channels at the afferent ending trigger postsynaptic potentials in the next neuron in the pathway.

Cellular Processes

The FASTER process involves rapid adaptation, while the SLOWER process involves slow adaptation.
The receptor potential in specialized afferent endings can trigger action potentials in afferent neurons.
Sodium ions are crucial for generating action potentials in afferent neurons by moving across the membrane through voltage-gated sodium channels.
The final destination of the action potential in the afferent neuron fiber is the central nervous system (CNS).

CNS Cells

Neurons are the primary cells in the central nervous system, responsible for transmitting information.
Astrocytes support neurons by providing nutrients, regulating neurotransmitter levels, and forming the blood-brain barrier.
Microglia act as the immune cells of the CNS, scavenging debris and protecting against pathogens.
Ependymal cells line the ventricles of the brain and spinal cord, helping to produce and circulate cerebrospinal fluid.
Oligodendrocytes form the myelin sheath in the CNS, insulating axons and increasing the speed of signal transmission.
Schwann cells form the myelin sheath in the peripheral nervous system.
Glial cells constitute a significant proportion of the nervous system, playing crucial roles in supporting, protecting, and modulating neuronal function.

Sensory Pathways

Afferent neurons carry sensory information from receptors to the CNS.
Dorsal root ganglia contain the cell bodies of afferent neurons, which are responsible for transmitting sensory information from the periphery.

Autonomic and Efferent Neurons

Autonomic division of the nervous system controls involuntary functions, such as heartbeat and digestion.
Efferent neurons carry signals from the CNS to muscles and glands.

Afferent vs. Efferent

Afferent neurons transmit sensory information from the periphery to the CNS.
Efferent neurons transmit motor commands from the CNS to muscles and glands.

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Description

Learn about the differences between tonic and phasic receptors, including how they respond to stimuli, adapt to changes, and generate on and off responses. Understand the characteristics of each type of receptor and how they process sensory information.