Sensory Receptors 1 & 2 Flashcards
what are the main classes of sensory receptor found in the body?
- mechanoreceptors
- thermoreceptors
- nociceptors
- electromagnetic receptors
- chemoreceptors
what is the role of mechanoreceptors?
detect mechanical compression or stretching of the receptor / of tissues adjacent to receptor
what is the role of thermoreceptors?
detect changes in temperature, with some receptors detecting cold and others warmth
what is the role of nocioceptors?
detect physical or chemical damage occurring in the tissues
what is the role of nocioceptors?
detect physical or chemical damage occurring in the tissues
what is the role of electromagentic receptors?
detect light on retina of eye; vision via rods and cones
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
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
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
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
what is a receptor potential?
the change in electrical
what is a receptor potential?
the change in electrical potential of the membrane (once a receptor has been stimulated)
how can a receptor potential be created via mechanoreceptors?
mechanical deformation which stretches receptor membrane and also opens ion channels
how can a receptor potential be created via chemoreceptors?
applications of a chemical to the membrane which opens ion channels
how can a receptor potential be created via thermoreceptors?
change in membrane temperature which changes the permeability of the membrane
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
