Lecture 12 - Saltatory Transmission, the NMJ and somatic reflexes Flashcards
Explain the role of myelin in determining the speed of action potential propagation.
myelination is a highly efficient adaptation in the nervous system, allowing for the rapid and energy-efficient transmission of action potentials. It plays a crucial role in the proper functioning of both the central and peripheral nervous systems, enabling the swift communication of information between neurons and throughout the body.
Explain the role of Schwann cells in determining the speed of action potential propagation.
Schwann cells are essential for myelinating axons in the PNS, which enables saltatory conduction and rapid action potential propagation. The myelin sheath, along with the nodes of Ranvier, allows action potentials to be efficiently regenerated and transmitted, contributing to the swift and effective communication of signals in the peripheral nervous system.
Explain the role of oligodendrocytes in determining the speed of action potential propagation.
oligodendrocytes in the CNS play a critical role in myelinating axons, which facilitates saltatory conduction and rapid action potential propagation. Myelin sheaths, along with the nodes of Ranvier, allow action potentials to be efficiently regenerated and transmitted, contributing to the swift and effective communication of signals within the central nervous system.
Explain the difference between continuous action potential propagation and saltatory action potential propagation
the main difference between continuous and saltatory action potential propagation lies in the presence or absence of myelin and the mechanism of signal transmission. Continuous propagation occurs in unmyelinated axons, travels more slowly, consumes more energy, and involves the entire axonal membrane. In contrast, saltatory propagation occurs in myelinated axons, travels faster, is energy-efficient, and involves the “jumping” of action potentials between nodes of Ranvier, leaving the insulated internodes inactive. Saltatory conduction is a specialized adaptation that enhances the speed and efficiency of signal transmission in the nervous system
Describe multiple sclerosis in relation to myeline sheath
multiple sclerosis is an autoimmune disease that primarily affects the myelin sheath in the central nervous system. The immune-mediated demyelination disrupts the normal conduction of electrical impulses along nerve fibers, leading to a wide range of neurological symptoms. Early diagnosis and appropriate management are crucial for individuals with MS to minimize disability and improve their quality of life.
Describe the structure of the NMJ
the NMJ is a highly specialized structure that allows for the efficient transmission of nerve impulses from motor neurons to muscle fibers, leading to muscle contraction. It involves a complex interplay of neurotransmitters, receptors, ion channels, and intracellular processes.
What is a motor unit?
A motor unit is the motor neurone and all the muscle fibres it innovates
What is DHP-receptor?
Dihydropryridine receptor (a modified voltage gated receptor)
What is RyR
a. Ryanodine receptor
b. And it is physically connected to DHP-R
Define and describe neural efferent and afferent pathways
afferent pathways carry sensory information from the periphery to the central nervous system, allowing us to perceive and respond to our environment, while efferent pathways transmit motor commands from the central nervous system to effectors, enabling voluntary and involuntary movements and bodily functions. Together, these pathways form the foundation for the body’s ability to sense, process, and react to stimuli, maintaining homeostasis and allowing us to interact with our surroundings
Describe the distinction in the organization of autonomic vs somatic efferent pathways
the key distinction in the organization of autonomic vs. somatic efferent pathways lies in their target tissues, modes of control, neuron chains, and the type of responses they govern. Somatic pathways control voluntary movements of skeletal muscles, while autonomic pathways regulate involuntary functions of smooth muscles, cardiac muscles, and glands, playing a critical role in maintaining homeostasis and bodily functions
Describe the location of primary sensory neuron cell bodies associated with spinal nerves
a. Located in the dorsal root ganglion (spinal ganglion)
b. the dorsal root ganglia serve as relay stations for sensory information, collecting signals from sensory receptors in the body and transmitting them to the spinal cord for further processing and relay to the brain.
Describe major somatic sensations
a. Tactile = touch and pressure
b. Proprioceptive = positive and movement
c. Thermometer = external temperature
d. Nociceptive = “pain”, risk of body injury
Describe the major visceral sensations
a. Mechanoceptive = blood pressure (baroreceptor)
b. Chemoceptive = pH, blood gas
c. Pain = referred pain
d. Temperature = core temperature
Define the term proprioception
a. Proprioceptors in the muscle and joints keep the brain and CNS aware of the bodies position in space
b. “sense of awareness of the position and movement of the body”
