Podcast
Questions and Answers
What is unique about the structure of first order neurons?
What is unique about the structure of first order neurons?
What happens when a stimulus from the outside world hits the sensory receptors?
What happens when a stimulus from the outside world hits the sensory receptors?
What is the significance of smaller receptive fields?
What is the significance of smaller receptive fields?
Why is two-point discrimination possible?
Why is two-point discrimination possible?
Signup and view all the answers
What is the function of the central branch of the first order neuron?
What is the function of the central branch of the first order neuron?
Signup and view all the answers
What is the primary function of the afferent division of the nervous system?
What is the primary function of the afferent division of the nervous system?
Signup and view all the answers
What type of receptors are responsible for detecting pain?
What type of receptors are responsible for detecting pain?
Signup and view all the answers
What is the term for the junction between two neurons, where one neuron sends signals to another?
What is the term for the junction between two neurons, where one neuron sends signals to another?
Signup and view all the answers
How many neurons are involved in the somatosensory pathways?
How many neurons are involved in the somatosensory pathways?
Signup and view all the answers
Where is the cell body of the third order neuron located in the somatosensory pathways?
Where is the cell body of the third order neuron located in the somatosensory pathways?
Signup and view all the answers
Study Notes
Nervous System Divisions
- The nervous system can be divided into afferent (sensory) and efferent (motor) divisions.
Afferent Division
- Brings sensory information from the outside world into the brain.
- Involves special senses (vision, hearing, taste, smell) and general somatic senses (somatosensory system).
- The somatosensory system is involved in the sense of touch, proprioception, pain, and temperature.
Sensory Neurons
- Found all over the body.
- Have receptors classified according to the stimulus they respond to:
- Mechanoreceptors for touch and proprioception.
- Nociceptors for pain.
- Thermoreceptors for temperature.
Neuron Structure
- Composed of a cell body (containing organelles) and nerve fibers (projections extending from the neuron cell body).
- Nerve fibers are either:
- Dendrites (receive signals from other neurons).
- Axons (send signals to other neurons).
Synapse
- Where two neurons come together.
- One end of an axon sends neurotransmitters to the dendrites or directly to the cell body of the next neuron in the series.
Somatosensory Pathways
- Made up of a relay of four neurons:
- First order neuron (sensory neuron) with sensory receptors that convert stimuli into an impulse.
- Second order neuron with its cell body in the spinal cord or brainstem.
- Third order neuron with its cell body in the thalamus.
- Fourth order neuron with its cell body in the sensory cortex of the brain.
First Order Neurons
- Also called pseudounipolar neurons.
- Have only one axon that extends out from the cell body, with two branches:
- Peripheral branch (goes from the cell body to peripheral tissues).
- Central branch (goes from the peripheral branch to the spinal cord).
Receptive Fields
- The area that a first order neuron receives sensory input from.
- Vary in size, with smaller receptive fields having higher resolution (allowing stimuli to be localized more precisely).
- Example: smaller receptive fields in the fingertips than at the back, allowing for high resolution in reading Braille.
Action Potential
- Triggered when a first order neuron reaches a certain threshold of depolarization.
- Sent through the peripheral branch and back to the central branch, and from there to the spinal cord.
Two-Point Discrimination
- Requires receptive fields of two sensory neurons to be separated by at least one neuron's receptive field.
- The third neuron sends a negative signal between the two positive ones, allowing two-point discrimination.
Studying That Suits You
Use AI to generate personalized quizzes and flashcards to suit your learning preferences.
Description
Learn about the two main divisions of the nervous system, afferent and efferent, and how they process sensory information from the outside world.