coordination system the senses
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COORDINATION SYSTEM THE SENSES. Ch.9/XI bil. Sensory system. Sense organs or receptors are receptors, it functions to receive information These organs are designed to receive stimuli which make us aware of changes taking place in our environment Receptor is an external stimulus receiver - PowerPoint PPT PresentationTRANSCRIPT
COORDINATION SYSTEM
THE SENSES
Ch.9/XI bil
Sensory system• Sense organs or receptors are receptors, it functions to
receive information• These organs are designed to receive stimuli which make
us aware of changes taking place in our environment• Receptor is an external stimulus receiver• Senses, which have special receptor cells to identify
changes in the external environment, have function to provide information ( heat, cold,pressure, touch etc)
• Stimulus from external environment is carried by the somatic nerve.
Sensory system• All the senses have highly specialized receptors enabling
them to respond to stimuli– Chemoreceptors : chemical– Photoreceptors : light– Phonoreceptors : sound– Tangoreceptors : touch/pressure
• Exteroreceptors = detects stimuli originating outside the body• Interoreceptors = detects stimuli originating inside the body• Proprioreceptors = located within the body muscles, joints
and bones (kinestetic)
Sense of touch
• The sense organ for touching and pressure is skin.
• The skin is richly supplied with nerve endings and these enable it to act as a sense organ
• Stimulation of nerve endings in the skin produces sensations related to temperature, pain and touch which are important for survival
Skin
• Type of receptors in skin Merkel : touch corpusclePaccini : pressure
corpuscleRuffini : heat
(thermoreceptor)Meissner : cold
corpuscleFree nerve endings :
pain
Sense of taste
• The tongue is covered by projections called papillae on the surface.
• The papillae contain taste receptors – taste buds
• The taste receptor is a chemoreceptor because it can be stimulated by various chemical substances
• Sense of taste depends to the sense of smell
Tongue• There are 4 main kinds of
tastes :Bitter : on the backSweet : on the tipSour : on the side to tipSalty : on the sides
Sense of hearing
• The sense of hearing is concerned with the perception of sound
• The ear is the only organ of hearing and it is also concerned with balance
• There is a close relationship between the sense of hearing and speech
Ear structure• Three parts of ear :
Outer ear (external)oAuricle/Pinna/flap : receive and collect the soundsoAuditory canal : is a canal, covered by hair, sebaceous
and ceruminous glands – secretes cerumen (ear wax) Middle ear
o Tympanic membraneo Ear bones (ossicles): responsible for the transmission
Malleus (hammer) Incus ( anvil) Stapes (stirrup)
o Eustachian tube : connect middle ear and pharynx
Ear structureInner ear (internal)
oOval windowo Semicircular canal : balance organ
• Sacculus• Utriculus• Ampula
oCochlea : Sound receptor
Ear
• Middle ear
The inner ear
• Semicircular canal • Cochlea
Anatomy of inner ear
• Within the cochlea, there is a fluid called perilymph and endolymph– Scala vestibuli– Scala media– Scala tymphani
Sound transmission
Sense of smell
• Smelling rods (olfactory rods) – bipolar cells – are located on the surface of the nasal cavity (upper part)
• The nose is both an organ of the respiratory system and sensory system
• The odor dissolves in the layer of moist mucous membrane covering the receptors in the upper nasal cavity. The impulses are transmitted to the brain for interpretation
The nose
Sense of sight• This sense organs responsible for vision.• Eye is the vision organ that composed of photoreceptor
cells that receive light (intensity and colour) – visual receptors in the retina are highly sensitive to light
• Two different receptors– Cone cells : for vision in bright day and colours– Rod cells : for vision in low light /night
• Accomodation power = ability to change lens shape and focal length that enables the eye to receive clear images of objects
Eye structure
The eye
• External structure
The eye
• Internal structure
Photoreceptors
Physiology of vision
Light transmission
The senses(summary)
Sense organ receptors Type of receptors
Type of stimulus
location
Sense of touch Nerve endings exteroreceptor touch skin
Sense of taste Taste buds exteroreceptor chemical tongue
Sense of smell Olfactory cell exteroreceptor chemical nose
Sense of hearing
Organ of corti exteroreceptor sound ear
Sense of sight Rod and Cones exteroreceptor light eye
Disorders and disturbances