types of receptors 2

8/11/2019 Types of Receptors 2

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nerveous tissue


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NERVEOUS TISSUE

Presentation

Made ByRABBIA SIDDIQUE VIRK


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Sensory nerve endings

The sensory nerve endings respond to stimuli

in the periphery and send nerve impulses to

the central nervous system(hence they may be

called beginnings)


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types of receptors

MORPHOLOGICAL CLASSIFICATION OF NERVE

ENDINGS

1) Nonencapsulated (free) nerve endings

2) Encapsulated nerve ending


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NONENCAPSULATED NERVE ENDING

constitute the most common variety of

sensory nerve endings in the body

these may be unmyelinated or fine myelinated

found in connective tissue fibres and cells and

around muscle fibre


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free nerve fibers

are functionally specialized to respond tosensation of pain,temperature and fine touch

in epidermis,

a no. of free nerve terminals form expended, disc likeendings which are associated with modified epithelialcells located in the stratum basale called merkel cells

collectively called as merkel corpuscle

function s specialized mechanoreceptors thatperceive discrimnatory touch found in finger tipsand lips


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ENCAPSULATED NERVE ENDINGS

nerve fibre terminals are enveloped by

specialized connective tissue capsules

greatly in shape and size


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CLASSIFICATION OF ENCAPSULATED

NERVE ENDINGS

meissner's corpuscles

pacinian corpuscles

ruffini's corpuscles krause's end bulbs

muscle spindles

golgi tendon organs


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MEISSNER'S CORPUSCLES

these are oval bodies measuring about 150 micro metre inlength and 75 micro metre in diameter found in, finger tips, palms and soles

eyelids, lips and nipples

They are covered by connective tissue capsule,continueswith epineurium

multilayered stacks of transversely disposed flattenedcells,which are supposed to be specialized Schwann cells found with in the capsule

They are concerned with the perception of touch sensationonly also known as tactile corpuscles of Meissner


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PACINIAN CORPUSCLES

large

ovoid structures

diameter, about 1-2 mm in length and 0.5-1 mm in diameter

contains one unmyelinated nerve fibre, which

becomes myelinated as it leaves the corpuscle


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INNER CORE

surrounds axon along entire length and consist of

many layers of tightly packed,flatened Schwann

cells

OUTER CORE

bulk of capsule consist of approximately 60

concentric layers found in deep dermis andhypodermis


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RUFFINI'S CORPUSCLES

fusiform structures

about 1-2mm in length and 0.2 mm in diameter

consist of thin connective tissue capsule

enclosing a fluid filled space this space is transversed by bundle of collagen

fibre that pass through capsule are joined toother collagen

ruffin's corpuscles are found indermis,subcutaneous tissue, joint capsule


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KRAUSE'S END BULBS

spherical bodies consisting of thin connective

tissue that surrounds a central cavity

a myelinated fibre enters the cavity loses its

myelin sheath, and divides into a number of

branches which terminate in club like endings

found in papillary layer of dermis of skin, in

peritoneum ,conjunctiva ,joints and external

genitalia


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MUSCLE SPINDLES

also called as neuromuscular spindles

a muscle spindle is generally less than a mmwide upto 5 mm long

each muscle consist of 6 to 14 modefiedstriated muscle fibres called intrafusal musclefibres

smaller in both diameter and length thanordinary muscle spindle called extra fusalmuscle fibre


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VARIETIES OF INTRAFUSAL MUSCLE

FIBRES

1) nuclear bag fibres

2) nuclear chain fibres

NUCLEAR BAG FIBRES

show a central bag like dilation in which areclustered numerous myonuclei

NUCLEAR CHAIN FIBRES

are thinner than nuclear bag fibres

exibit only single row of myonuclei in their centralpart


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GOLGI TENDON ORGANS

found in

tendons and are located near the muscletendon

junction

are cylinderical structures

about 0.1 mm in diameter and 1 mm in length

consist of fiberous capsule which contains a

bundle of loosely arranged, wavy collagen

fibres called intrafusal collagen fibres


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nerve impulses from the golgi tendon organs

reach the interneurons in the spinal cord,

which in turn exert an inhibtory influence on

alpha motor neuron

located in anterior grey horns of spinal cord,

causing relaxation of muscles to which the

particular tendon is attached


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types of receptors 2

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