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SENSORY ORGANS AND SYSTEM - Coggle Diagram
SENSORY ORGANS AND SYSTEM
Types of sensory receptors
Type of stimulus
Mechanoreceptors ( respond to touch/pressure )
Thermoreceptors ( respond to temperature changes)
Photoreceptors ( respond to light )
Chemoreceptors ( respond to specific chemicals )
nociceptors ( respond to damaging stimuli )
Location on the body
exteroceptors ( respond to stimuli outside of the body )
Interoceptors ( respond to stimuli inside the body )
Proprioceptors ( respond to stimuli in skeletal muscle and related connective tissues )
Structure
Nonencapsulated nerve endings
Encapsulated nerve endings
Lamellar corpuscles
Bulbous corpuscles
Muscle spindles
Tendon organs
Ear
External and middle ear
transmit airborne sound waves to the fluid-filled inner ear, amplifying sound energy
Inner ear
contains receptors for conversion of sound wave into nerve impulses, making hearing possible
for the sense of equilibrium
Pathway of sound
Pathway 1
Through the scala vestibuli, around the helicotrema, and through the scala tympani, causing the round window to vibrate.
Pathway 2
A shortcut from the scala vestibuli through the basilar membrane. This pathway triggers activation of the receptors for sound by bending hairs of hair cells
The
Nose
The olfactory mucosa
olfactory receptor cells
supporting cells
basal cells
The smell depends on the olfactory receptor cells detecting odours or scents
To be smelled, the substance must be;
Sufficiently volatile so that some of its molecules can enter the nose in the inspired air
Sufficiently water soluble so that it can dissolve in the mucus coating the olfactory mucosa
Tongue
The receptor for taste and smell are chemoreceptors, which generates neural signals on binding with particular chemicals in environment.
Taste Bud
Content chemoreceptors
Has a small opening taste pore
Consists of about 50 long, spindle- shaped taste receptor cells with supporting cells
Signals in sensory inputs are conveyed via synaptic stops in the brain stem and thalamus to the cortical gustatory area (region in parietal lobe adjacent to the tongue area)
Taste signals are also sent to the hypothalamus and limbic system to add effective dimensions
5 Primary Taste
Triggered by amino acids (glutamate)
Elicited by alkaloids and poisonous substance
Evoked by the particular configuration of glucose
Caused by acids, which contain a free hydrogen ion, H+.
Stimulated by chemical salts (table salts
Nerve
Types of nerve
Mixed nerves
contain both sensory and motor neurons
Transmit impulses to and from the CNS
Sensory nerves
contain sensory neurons
Transmit impulses to the CNS
Motor Nerves
Contain motor neurons
transmit impulses from the CNS
Cranial Nerves ( 12 pairs )
Nerve from the brain
Spinal Nerves ( 31 pairs )
Extend from the spinal cord to areas of the body
Eye
Eye anatomy: Cornea, anterior chamber, lens, vitreous chamber, retina, aqueous humor
Retina: sensing layers of 5 nerve cell types (photoreceptors, bipolar, horizontal, amacrine and
ganglion)
Photoreceptor is made up photopigments which are rods (black and white perception) and
cones (three different pigments for color perception).
Photoreceptors converges into a bipolar cell, bipolar cells converges into a ganglion cell, everywhere except at the fovea (1-to-1 connection between photoreceptors and ganglion cells).Axons sweep across the retina from ganglion cells to form optic nerve.
Direction of light sequence:
Front of retina
Optic nerves fibres
Ganglion cells
Amacrine cells
Bipolar cells
Horizontal cells
Photoreceptors cells
Direction of retinal visual processing:
Photoreceptor cells
Horizontal cells
Bipolar cells
Amacrine cells
Ganglion cells
Optic nerve fibres
Front of retina