10 Questions
Which type of receptors react to stimuli from within the body related to the degree of filling or stretch of organs like the alimentary canal and bladder?
Enteroceptors
What type of receptor provides sensation of body position, muscle tone, and movement?
Proprioceptors
Which type of receptor is a bare axon called a nonencapsulated (free) nerve ending?
Encapsulated nerve endings
What kind of sensory endings are encapsulated by connective tissue sheaths?
Pacinian corpuscles
Which sensory receptor is sensitive to skin stretch?
Ruffini's corpuscles
Where are muscle spindles located?
Within skeletal muscle
What do Golgi tendon organs detect?
Tension at musculotendinous junctions
Which part of a peripheral nerve surrounds bundles of axons with connective tissue?
Perineurium
What term is used to describe the outermost layer of a peripheral nerve that protects the nerve from surrounding tissues?
Epineurium
Which type of peripheral nerve fibers carry signals towards the central nervous system?
Afferent fibers
Study Notes
Peripheral Nervous System (PNS)
- Composed of peripheral nerves, specialized nerve endings, and ganglia containing nerve cell bodies outside the central nervous system
Peripheral Nerves
- Made up of many nerve fibers carrying sensory and motor information between the body and the brain and spinal cord
- Nerve fibers can refer to the axon with its coverings (myelin and Schwann cell) or the axon alone, or any process of a nerve cell (dendrite or axon)
Connective Tissue Components of a Peripheral Nerve
- Endoneurium: loose connective tissue surrounding individual nerve fibers, with sparse fibroblasts, collagen fibrils secreted by Schwann cells, and mast cells and macrophages
- Macrophages mediate immunologic surveillance and participate in nerve tissue repair
- Perineurium: specialized connective tissue surrounding each nerve fascicle, serving as a metabolically active diffusion barrier and contributing to the blood-nerve barrier
- Perineurial cells are squamous, with external (basal) lamina on both surfaces, and contain actin filaments
- Tight junctions between perineurial cells provide the basis for the blood-nerve barrier
- Epineurium: dense irregular connective tissue surrounding a peripheral nerve and filling the spaces between nerve fascicles, often associated with adipose tissue
Functions of Peripheral Nerves
- Establish communication between centers in the CNS and sense organs and effectors (muscles, glands, etc)
- Contain both afferent and efferent fibers
- Afferent fibers carry information from internal body regions and the environment to the CNS
- Efferent fibers carry impulses from the CNS to effector organs
- Nerves can be classified as sensory, motor, or mixed nerves, with some having both myelinated and unmyelinated axons
Afferent (Sensory) Receptors
- Specialized structures located at the distal tips of the peripheral processes of sensory neurons
Learn about the structure and components of the peripheral nervous system (PNS), including peripheral nerves, specialized nerve endings, and ganglia outside the central nervous system. Explore how sensory and motor information is transmitted between the body organs and brain/spinal cord.
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