sensory system

 Sensory system

The process of sensation begins in sensory receptors which can a sensory neuron.

The special senses of hearing, sight, smell and taste all have specialized sensory receptors (nerve endings) outside brain.

Thses are found in head, nose, ear, eyes, mouth.

In brain incoming nerve impulses undergo process of integration and coordination that result in perception of sensory information and variety of respnses inside and outside body.

Upto 80% of what we perceive come from sensory stimuli.

Classification of senses

1. General senses

Include touch, pressure, pain, temperature, vibration, proprioception.

Somatic senses; touch, pressure, temperature, pain, proprioception.

Visceral senses; consist maily pain and pressure, for example; blood pressure increased.

2. Special senses

Smell, taste, sight, vision, touch

Sensation or perception

Conscious awareness of stimuli received by sensory receptors.

Stimulus - receptors - action potential-  CNS and transmitted within brain.

Types of Sensory receptors 

1. Somatic

Touch; mechanoreceptors

Detect touch, pressure, vibration, hearing, equibrium, proprioception

Temperature; thermoreceptors 

Detect changes in temperature ( in skin).

Pain; Nociceptors (pain receptors)

Extreme heat, extreme cold, excessive pressure, inflammatory chemical

2. Visceral

Baroreceptors; detect changes in blood pressure.

Pain; Nociceptors; pain receptors

Pressure; mechanoreceptors

Osmoreceptors; detect levels of osmotic pressure in body fluid.

3. Special

Smell; chemoreceptors

Taste

(Detect changes in chemical environment)

Sight; photoreceptors; detect light (in retina of eye)

Sound; mechanoreceptors

Balance; mechanoreceptors