Flashcards in Neuroanatomy Pages 19- Deck (50)
What are sensory systems responsible for? (3)
-Collecting info regarding external & internal environment
-Conveying info from PNS to CNS
-Sensory info is utilized by CNS in various ways
In what ways is sensory info utilized by the CNS?
- conscious appreciation of specific qualities of sensory stimulus
- appropriate reflex response to a stimulus
What do sensory receptors of the PNS do?
- monitor changes in external & internal environment
- serve as biological transducers- monitor stimuli
- the info generated in PNS gets sent to CNS
What are primary sensory neurons?
Sensory neurons in PNS
Cell bodies of primary sensory neurons are located where?
Peripheral ganglia of spinal and cranial nerves
Peripheral processes innervate what?
Peripheral sensory receptors in peripheral tissues
Central processes project into what?
into the CNS
What are the classifications of stimulus receptors and they're functions?
Chemoreceptors- monitors changes in concentration of various chemical species in tissues
Mechanoreceptors- physical or mechanical stimuli
Nociceptors- noxious stimuli (potentially harmful- chemical, mechanical, or thermal stimuli)
What is the difference between a nonencapsulated and an encapsulated ending?
Nonencapsulated- terminals of axons that lie next to cells or free in the extracellular space
Encapsulated- consist of terminals of axons enclosed by a capsule of non-neuronal cells
What are the 3 types of nonencapsulated ending receptors?
- Free nerve endings- axon terminals distributed between cells
- Merkel endings/discs- associated with cells located in deep layers of epidermis (hairless especially)
- Peritrichial nerve endings- associated with axon terminals distributed along root of hair follicles
What are the 5 types of encapsulated ending receptors?
- Pacinian corpuscles- single axon terminal with layers o non-neural cells
- Meissner's corpuscles- one or more axons inside capsule- highly branched (long and slender capsule)
- Ruffini endings- single axon inside delicate capsule
- End bulbs- variable size & shape - often round - highly branched - often found at muco-cutaneous junctions
- Others: neuromuscular spindles (skeletal muscle) & neurotendinous spindles (tendons & ligaments- Golgi)
Where are the free nerve endings found in cutaneous areas and what do they monitor?
- epidermis, dermis, subcutaneous tissue
- monitor thermal, painful (noxious), and tactile stimuli
What do the peritrichial endings in cutaneous areas monitor?
Movement of hair (tactile)
Where are Merkel endings found in cutaneous areas and what do they detect?
Deep layer of epidermis
Where are Ruffini endings found in cutaneous areas and what do they detect?
Dermis & subcutaneous tissue
Where are Meissner's corpuscles found in cutaneous areas and what do they detect?
Dermal papillae of mostly glabrous (hairless) skin, especially fingertips
Where are Pacinian corpuslces found in cutaneous areas and what do they detect?
Dermis & subcutaneous tissues
Mechanoreceptors that detect vibration
What 4 type of receptors are found in joints? Where and what kind of stimuli do they detect?
- Free nerve endings- synovial membrane (proprioception), joint capsule, & periarticular CT (nociception)
- Small pacinian corpuscles- periarticular CT around joint capsule- proprioception
- Ruffini- joint capsular tissue- proprioception
- Neurotendinous spindles (Golgi tendon organ)- in articular ligaments- proprioception
What 2 types of receptors are found in skeletal muscles?
- Free nerve endings- mainly CT around muscle- nociceptor
- Neuromuscular spindles- in muscle near junction with tendon - proprioception
What 2 types of receptors are found in tendons?
Free nerve endings- nociceptors & proprioceptors
Golgi tendon organs- proprioceptors
What 2 types of receptors are found in viscera?
- Free nerve endings- nociceptors, chemoreceptors, stretch/distension
- Pacinian corpuscle- fullness/distension
What are the functions of A-alpha fibers?
- motor to skeletal muscle
- sensory from neuromuscular spindle
What is the function of A-beta fibers?
- sensory from neuromuscular spindles, Ruffini endings, GTO's, Meissner's, and Pacinican corpuscles
What is the function of A-gamma fibers?
Motor to neuromuscular spindles
What is the function of A-delta fibers?
- Peritrichial endings, pain and temperature receptors
What are the functions of B fibers?
- Preganglionic autonomic fibers
- Sympathetic & Parasympathetic
What are the functions of C fibers?
- Postganglionic autonomic fibers, pain & temperature receptors
- Nociceptic information
Which of the A, B & C fibers is unmyelinated?
What type of receptor is a Ia fiber, and what is it's equivalent?
Neuromuscular spindle, A-alpha