Lab 13
structure of neurons
structure of neurons
Fichier Détails
| Cartes-fiches | 54 |
|---|---|
| Langue | English |
| Catégorie | Biologie |
| Niveau | Université |
| Crée / Actualisé | 09.03.2015 / 12.09.2023 |
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Describe Afferent Nerves.
Sensory nerves that carry information TOWARDS THE CNS. A few of the cranial nerves are purse sensory nerves.
Describe Efferent Nerves
Carry impulses AWAY from the CNS. The ventral roots of the spinal cord are motor nerves.
Describe MIXED NERVES
Carry both afferent and efferent signals - most nerves of the body, including all spinal nerves.
Describe the three tissue shealths of a nerve.
Endoneurium - outter layer of the nerve which insulates it from other neuron processes adjacent to it. Surrounds mylien shealth.
Perineurium - Surrounds groups of axons and is a coarser connective tissue to form bundles of tissue called FASICLES.
Epineurium - Binds all the fasicles together - forming a cordlike nerve.
What are sensory receptors?
Either modified dendritic endings or specialized cells associated with the dendrites that are sensitive to certain environmental stimuli. They react to such stimuli by initiating a nerve impulse.
Name the classifications of sensory receptors by the stimulis they detect.
Exteroceptors, Interoceptors, Proprioceptors.
Describe Exteroceptors -
Respond to stimuli in their external environment and are typically found close to the body surface.
Describe Interoceptors -
Respond to stimuli arising within the body (including the visceral organs).
Describe proprioceptors.
A subclass of interoceptors, are found in skeletal muscles, joints, tendons, and ligaments and report on the degree of stretch in these structures.
Where are cutaneous and proprioceptors located?
Cutaneous - reside in the skin
Proprioceptors - located in skeletal muscles, tendons and join capsules.
What are nonencapsulated free nerve endings?
They are endings of sensory neurons which respond chiefly to pain and temperature.
What are tactile epithelial complexs?
Also called merkel discs - they are free nerve endings associated with merkel cells to created merkel discs. Or they entwine in hair follicles to form hair follicle receptors. They generally function as light touch sensors.
Describe the tactile corpuscle
respond to light touch, located in the dermal papillae of hairless skin only.
Describe the Bulbous corpscles.
appear to respond to deep pressure and stretch stimuli.
Describe the lamellar corpsuscles
anatomically more distinctive and lie deepest in the dermis. These receptors respond only when deep pressure is first appplied. Best suited to high-frequency vibrations. Anatomically more distinctive than other receptors.
What are the two differen't regisons of the nervous syste?
The Central Nervous Systen and the Perepherial nervous system
What does the CNS include?
The brain and the spinal cord
What does the PNS include?
Everything outside of the CNS, nerves, sensory receptors and some clusters of nerve cells.
What are the two main cell types of the nervous system?
Neuroglia and Neruons
What are the Neuroglia found in the CNS?
Astrocytes, Oligodendrocytes, microglial
What are the Neuroglia found in the PNS?
Schwan cells, satellite cells
What are the functions of the Neuroglia?
- brace and protect
- act as phagocytes (microglial cells)
- capilary exchange and chemical enviornment control (astrocytes)
- mylenation - (schawn cells and oligodendrocytes)
What are neurons? What do neurons do?
basic functional units of the neurvous tissues. Highly specialized to transmit messages via electical signals.
Describe the cell body of the neuron.
a large central area of which long extensions extend. It is the biosynethic center of the neuron as well as the receptive region. It contains a large round nucleus surrounded by cytoplasm.
What are groups of cell bodies called in the CNS? In the PNS?
CNS - make up the grey matter of the CNS forming clusters called nuclei
PNS - Clusters of neuron cell bodies are called ganglia
Whar are the two prominent features found in the cytoplasm of the nueron? what do they do?
1. Neurofibrils - provide support for the cell and a means for transport of substances through the neuron.
2. Chromatophilic substance (Nissl bodies) - an elaborate type of rough ER involved in the metabolic activity of the cell.
What are the two types of processes found on a neuron?
Dendrites and Axons
What are dendrites?
receptive regions that bear receptors for neurotransmitters released by the terminal boutons of other neurons.
What are axons?
Also called nerve fibers, form the impulse-generating and impulse-conducting region of the neuron.
What makes up the white matter of the nervous system?
Axons
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