Peripheral Senses 9(d)

Referred Pain The phenomena in which pain caused in one region of the body is felt in another region is called referred pain. Can you think of any regions in which pain is felt but occurs elsewhere? – Stomach pain manifests sometimes in the form of “heartburn” in the chest – The heart muscle can exhbit pain/ distress over the area of the left shoulder and arm. – The lungs exhibit pain over the left neck. – The liver & gallbladder exhibit pain over the right neck. Referred pain is caused by: nerves from different regions crossing nearby on the spinal cord.

Somatic (Body) Senses

Somatic Senses What are the five senses of our PNS? (Peripheral nervous system) 1.Touch (tactile perception) 2.Smell (olfaction) 3.Taste 4.Hearing 5.Vision

Somatic Senses Tactile perception (touch) – Mechanoreceptors Detects tactile sensation. – Nociceptors Detects pain. – Thermoreceptors Detects temperature variations. – There are many more receptors!

Somatic Senses Olfaction (smell) – Olfactory receptors Detect the chemical makeup. – Humans can detect about 17,000 smells. – We have 10cm 2 surface area of receptors. – Dogs can detect many more smells! – They have 170cm 2 surface area for receptors! – We have one of the weakest smells in the animal kingdom…

Somatic Senses Taste – Fungiform papillae Mushroom-like bundle on tongue, contains taste buds. – Five flavors Sweet, sour, salty, bitter, umami

Somatic Senses Hearing – Tympanic Membrane Eardrum. Vibrates form sound pressure.

Somatic Senses Vision – Rods Cells on the retina which detect light and dark. – Cones Cells on the retina which detect color. Q: Why can cats see well in the dark, but we can’t? A: Because they don’t have any cones – all those extra rods do great at night vision. Humans have many cones – cones are unable to function in low-light.

Blind spot Optic nerve Retina Choroid Layer Sclera

Sclera (white part of eye)

Blind spot Optic nerve Retina Choroid Layer Sclera Iris Lens Cornea Conjunctiva

Conjunctivitis (pink eye)

Blind spot Optic nerve Retina Choroid Layer Sclera Iris Lens Cornea Conjunctiva Pupil

Iris & Pupil

Blind spot Optic nerve Retina Choroid Layer Sclera Iris Lens Cornea Conjunctiva Pupil Suspensory Ligament Ciliary Muscle

Testing for the blind spot.