body senses Flashcards
3 somatosenses
cutaneous sense
organic (internal) sense
vestibular sense
cutaneous sense
sensitivity to stimuli that involve the skin
eg pressure, vibration, temperature and pain
organic (internal) sense
a sense modality that arises from receptors within the inner organs of the body and muscles
proprioception - ability to sense position of the body and limbs
vestibular sense
perception of the bodies position, movement and balance
vestibular system
part of the inner ear
made up of 3 semicircular canals and the vestibular sacs
system filled with fluid
movement of fluid bends stereo cilia on hair cells (mechanoreceptors)
become excited
send a nerve impulse to Bain via vestibular nerve
how vestibular system detects head position
position of fluid in vestibular sacs detects head position
static head tilt and linear acceleration
movement of fluid in the semicircle canals
detect head rotation movements
structure of the skin
heaviest and largest organ, multiple layers
epidermis
thin, outer layer that provides a protective barrier against pathogens
dermis
thickest layer containing connective tissue, capillaries, hair follicles and sensory receptors
hypodermis
bottom layer of subcutaneous tissue/fat
5 receptors detecting specific stimuli
free nerve endings
mechanoreceptors:
Merkel receptors
Meissner corpuscle
Ruffini cylinder
Pacinian corpuscle
free nerve endings
unencapsulated dendrites of sensory neurons - free ends
found in both hairy and non-hairy skin
locked close to the epidermis and in hairy skin
surround hair follicles
distributed around bones, within muscles and internal organs
respond to damaging stimuli
- different types with respond to heat, pressure, temperature etc
Merkel receptors
fire continuously in response to pressure
responsible for sensing fine details, shape and texture
have small receptive field
Meissner corpuscle
fires only when a stimulus is first applied and removed
responsible for controlling hand grip and sensing motion across the skin
Ruffini cylinder
fires continuously in response to stimulation
associated with perceiving stretching of the skin
located deep within dermis
Pacinian corpuscle
fires only when a stimulus is first applied and removed
association with sensing rapid vibrations and fine texture
located deep within dermis
purpose of internal senses
sensory nerve endings in our internal organs, bones and joints protect against possible damage from strain
specially receptors in our muscles detect changes in muscle length
mechanoreceptors respond to the movement and angles of joints
together = proprioception, our sense of body position and movement
2 information pathways for internal senses
spinothalamic tract
medial lemniscus
both carry information in same way
skin to spinal cord in 1st order neuron
spinal cord to thalamus in 2nd order neuron
onto somatosensory cortex by 3rd order neuron
