Sense (special and general)

Special Senses?

Vision

hearing

taste

smell

General Sense

Touch

General Sensory Pathway Vs special sensory pathway

general- ONLY 3 neurons involved

special- at LEAST 3 neurons involved

Photoreceptors

respond to light

Nociceptors

respond to chemicals from damaged tissue (pain)

Thermoceptors

respond to changes in temp

Chemoreceptors

respond to chemicals (must be dissolved in solution)

mechanoreceptors

respond to mechanical forces

types of mechanoreceptors

1. proprioceptors

2. barorecptors

3. stretch receptors

4. golgi tendon organ

Proprioceptors

senses changes in tension of muscles an tendons

helps maintain equilibrium and body sense of stability

Baroreceptors

sense changes in pressure

stretch receptors

sense changes in length of muscles

how do stretch receptors work?

1. when the muscle is stretched rapidly, muscle spindle fibers send signals to the spinal cord

2. spinal cord signals a reflex contraction of the same muscle

3. prevents overstretching

Golgi Tendon Organ (GTO)

senses tension from a muscle

how does the Golgi Tendon Organ work?

if tension gets too high, GTO sends a signal to the spinal cord

spinal cord signals same muscle to relax

prevents over contraction

Referred Pain

pain felt in a part of the body other than it’s actual source

(aka visceral pain)

Eyelid layers

1. outermost- skin

2. muscle- orbicularis oculi

3. conn. tissue

4. innermost- conjunctiva

1. Eyelid

Conjunctiva,

function and pathology

fold back to cover eye’s anterior surface

if it’s inflamed- conjunctivitis

1. Eyelid

Tarsal Gland

function and pathology

secrets an oily fluid to decrease friction b/w eyelid and eye surface

if inflamed and blocked- stye

1. Eyelid

Locator Palpebrae Superioris

smooth muscle

holds eyelid when awake

Accessory Structures of the Eye

1. eyelid

2. lacrimal apparatus

3. extrinsic muscle of eye

2. Lacrimal Apparatus

lacrimal gland

produces tears

2. Lacrimal Apparatus

S&I Canalculi

drains tears from medial corner of the eye

2. Lacrimal Apparatus

Lacrimal Sac, inside what bone?

lacrimal nasolacrimal duct-into nasal cavity

3. Extrinsic Muscle of the Eye

Lateral Rectus- CN, movement

-CN VI (abducens)

-movement- laterally

3. Extrinsic Muscle of the Eye

Superior Rectus- CN, movement

-CNIII (oculomotor)

movement- superiorly

3. Extrinsic Muscle of the Eye

Inferior Rectus- CN, movement

-CNIII (oculomotor)

movement- inferiorly

3. Extrinsic Muscle of the Eye

Medial Rectus- CN, movement

-CNIII (oculomotor)

movement- medially

3. Extrinsic Muscle of the Eye

Inferior Oblique- CN, movement

CN III (oculomotor)

movment- superior, laterally

3. Extrinsic Muscle of the Eye

Superior Oblique- CN, movement

CN IV (trochlear)

movement- inferior and lateral

Structure of the Eye

Wall- 3 layers

1. outer- fiberous

2. middle- vascular

3. inner- nervous

Structure of the Eye

2 structures of the outer (fiberous) layer

1. sclera- whites of the eye, the majority of the fibrous layer, mostly posterior. some anterior

2. cornea- anterior- bulges outwards, no blood vessels

Structure of the Eye

Midde Vascular layer has what? (list them)

many structures

choroid

cilliary body

iris

pupil

lens

Structure of the Eye- Vascular Layer

Choroid

lines interior sclera

dark brown

Structure of the Eye- Vascular Layer

Cilliary Body (4)

smooth muscle

anterior part of choroid

attaches to the lens by suspensory ligaments

muscle contraction changes lens thickness

Structure of the Eye- Vascular Layer

Iris- rainbow (4)

colored part of the eye (pigment)

contains smooth muscle fibers

suspensed b/w cornea and lense

opening in the middle (pupil)

Structure of the Eye- Vascular Layer

Pupil characteristics

can dialate and constrict to regulate light

contains radial fibers (dialator Pupilae M.)

Structure of the Eye- Vascular Layer

Pupil responses

dim light- sympathetic response, has circular fibers (constrictor pupilae M.)

bright light- parasympathetic

Structure of the Eye- Vascular Layer

Lens (4)

posterior to iris/pupil

transparent, avascular

held in place by suspensory ligaments

ciliary body muscle contraction changes the tension on the ligaments, changing the thickness

Cavities/ Chambers of the Eye

Anterior Cavity- location and subdivisions

from cornea to lens

1. anterior chamber (from cornea to lens)

2. posterior chamber (from iris to lens)

Cavities/ Chambers of the Eye

Posterior Cavity location

from lens to retina