Sensory Receptors 1 & 2 Flashcards by Anna Dunlop

what are the main classes of sensory receptor found in the body?

mechanoreceptors
thermoreceptors
nociceptors
electromagnetic receptors
chemoreceptors

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what is the role of mechanoreceptors?

detect mechanical compression or stretching of the receptor / of tissues adjacent to receptor

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what is the role of thermoreceptors?

detect changes in temperature, with some receptors detecting cold and others warmth

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what is the role of nocioceptors?

detect physical or chemical damage occurring in the tissues

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what is the role of nocioceptors?

detect physical or chemical damage occurring in the tissues

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what is the role of electromagentic receptors?

detect light on retina of eye; vision via rods and cones

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what is the role of chemoreceptors?

detects taste in the mouth, smell in the nose, oxygen level in arterial blood, osmolality of body fluids, carbon dioxide concentration, and other factors that make up the chemistry of the body

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what are the different aspects detected by chemoreceptors?

TASTE
- receptors of taste buds

SMELL
- receptors of olifactory epithelium

ARTERIAL OXYGEN
- receptors of aortic and carotid bodies

OSMOLALITY
- neurons in or near supraoptic nuclei

BLOOD CO2
- receptors in or on surface of medulla and in aortic and carotid bodies

BLOOD GLUCOSE, AMINO ACIDS, FATTY ACIDS
- receptors in hypothalamus

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what are the different aspects detected by chemoreceptors?

TASTE
- receptors of taste buds

SMELL
- receptors of olifactory epithelium

ARTERIAL OXYGEN
- receptors of aortic and carotid bodies

OSMOLALITY
- neurons in or near supraoptic nuclei

BLOOD CO2
- receptors in or on surface of medulla and in aortic and carotid bodies

BLOOD GLUCOSE, AMINO ACIDS, FATTY ACIDS
- receptors in hypothalamus

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what are the different aspects detected by chemoreceptors?

TASTE
- receptors of taste buds

SMELL
- receptors of olifactory epithelium

ARTERIAL OXYGEN
- receptors of aortic and carotid bodies

OSMOLALITY
- neurons in or near supraoptic nuclei

BLOOD CO2
- receptors in or on surface of medulla and in aortic and carotid bodies

BLOOD GLUCOSE, AMINO ACIDS, FATTY ACIDS
- receptors in hypothalamus

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what is a receptor potential?

the change in electrical

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what is a receptor potential?

the change in electrical potential of the membrane (once a receptor has been stimulated)

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how can a receptor potential be created via mechanoreceptors?

mechanical deformation which stretches receptor membrane and also opens ion channels

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how can a receptor potential be created via chemoreceptors?

applications of a chemical to the membrane which opens ion channels

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how can a receptor potential be created via thermoreceptors?

change in membrane temperature which changes the permeability of the membrane

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how can a receptor potential be created via electromagnetic receptors?

effects of electromagnetic radiation e.g. light on visual receptor which changes receptor membrane characteristics allowing ions to flow through membrane channels

what is the maximum amplitude of most sensory receptor potentials?

100 millivolts

what is the maximum amplitude of most sensory receptor potentials?

100 millivolts

what is the maximum amplitude of most sensory receptor potentials?

100 millivolts

what are the main types of cutaneous receptors?

pacini’s corpuscles
meissner’s corpuscles
merkel disks
ruffini corpuscles
skin hair receptors

what are features of pacini’s corpuscles?

largest mechanoreceptor (2mm)
onion like encapsulation of nerve endings
found in deep layers of dermis
detects high frequency (40-500Hz) vibration
Aβ fibres
glabrous & hairy skin types
rapidly adapting due to slick viscous fluid between layers
low activation threshold

what are features of meissner’s corpuscles?

encapsulated nerve endings similar to pacini’s but smaller
stacks of discs interspersed with nerve branch endings
found between dermal papillae
detects touch, flutter and low frequency vibration (2-40Hz)
Aβ fibres
glabrous skin types
low activation threshold

what are features of merkel disks?

non-encapsulated nerve endings
detect static touch and light pressure
Aβ fibres
glabrous & hairy skin types
consist of specialised epithelial cell + nerve fibre
slowly adapting
just under skin surface e.g. fingertips
good discrimination
multiple branches found in ‘Iggo Dome’

which cutaneous receptors work together to determine texture?

meissner’s corpuscles

- merkel disks

what are features of ruffini corpuscles?

- encapsulated nerve endings - responds to skin stretch - located in deeper layers of skin, tendons and ligaments - glabrous & hairy - esp. abundant in hands, fingers, soles of feet - nerve endings weave between collagen fibres which activate nerve when pulled longitudinally

what are features of skin hair cell receptors?

- skin hair cell has mechanosenstivive receptor wrapped around follicle - detects muscular movements of hair (erector muscle) - detects external displacements of hair

what is the relation of receptor potential to action potential?

- when receptor potential rises above the threshold for eliciting action potentials in the nerve fibre attached to the receptor, then action potential occurs - the more receptor potential rises above threshold levels, the greater the action potential frequency becomes

how do we "know" the modality?

- nerve fibres transmit ONLY impulses - nerves terminate at specific point in CNS and the types of sensation felt is determined by the point in the NS to which the fibre leads - modal information is also delivered to the CNS in a topographic fashion i.e. pain from leg is delivered to a particular part of the CNA which is different to, but near, stretch or vibration signals from the leg

how does phantom limb sensation arise?

when sensory neurons from absent limbs are spontaneously active, and can be mimicked by electrical stimulation

what is the precision of localisation of a particular stimulus determined by?

- size of individual nerve fibre receptive field - density of sensory units - amount of overlap in nearby receptive fields

how does receptor field distribution and size differ between receptor types?

- different sensory modalities are used by the brain to describe the world around us - the quality of information will relate directly to our ability to comprehend them - the higher the resolution, and the higher the number of modalities for a given situation, the better the understanding will be - pacini's corpuscles and meissner's corpuscles are both sensitive, but have different receptor field sixes which reflect their differing roles in cutaneous sensation

what is two point discrimination?

the ability to discern that two nearby objects touching the skin are truly two distinct points, not one

what causes variation in results of two point discrimination test?

result of receptive field size and receptor density in area

what is lateral inhibition?

the capacity of an excited neuron to reduce the activity of its neighbors. Lateral inhibition disables the spreading of action potentials from excited neurons to neighboring neurons in the lateral direction

what is the function of lateral inhibition?

aids in enabling localisation of stimulus