The special senses Flashcards
Sense organs are;
Information on your surroundings
processed in the CNS
5 special senses;
Senses
Somatosensory system (pressure, warmth, vibration, limb position)
Sight (Visual system)
Hearing (Auditory system)
Taste (Gustatory system)
Smell (Olfactory system)
Eye; Vision is the dominant sense in humans
How are they protected?
by orbit and cushion of fat
Accessory Structures
Eyebrows
Eyelids or palpebrae
eyelids allow to blink
Eyelashes
keeping airborne dirt, dust, lint and other debris from reaching the delicate eye tissues
Conjunctiva
transparent mucous membrane
Lacrimal apparatus
Lacrimal gland: Responsible for tears (PNS)
mucus, antibodies and lysozyme
nasolacrimal duct —> nasal cavity
Extrinsic Eye Muscles
Movement
Eye ball; 3 tissues/tunics
1) Fibrous Layer (Outer)
2) Vascular layer
3) Nervous tissue layer (inner most)
1) Fibrous Layer (Outer) - is made out of what 2 things, colour?
Sclera: white of the eye
Cornea: front of the eye (transparent)
Choroid
Dark: melanin containing cells
Absorbs light
2) Vascular layer (has a LOT of blood vessels in it)
Choroid
Dark: melanin containing cells
Absorbs light
Ciliary body
Cilliary muscles
Change thickness of Lens
Iris
Coloured part of eye
Highly vascularised
Pupil size controlled by muscles of the iris
Light passes through pupil
3) Nervous tissue layer (inner most)
Retina
Outer Pigmented retina
Prevents light reflection
Inner sensory retina
Why is the Cornea transparent?
light needs to pass through it (this is the outer layer of the eyeball)
How many chambers are there in the eye?
2 =
Anterior Segment / cavity (FRONT) + Posterior segment/cavity (BACK)
What is the anterior cavity made up of?
ANTERIOR CHMABER
chamber between cornea and iris
POSTERIOR CHAMBER
chamber between iris and lens
AQUEOUS HUMOR: Fills Anterior Segment
Watery liquid, replaced continuously
Filtered through ciliary body and returned to blood via venous synus
Nutrients
Refracts light
Maintains pressure
Posterior segment/cavity COMPOSITION?
VITREOUS CHAMBER
VITREOUS HUMOR: in posterior segment
Jellylike
Maintains pressure and refracts
Forms in embryo and doesn’t circulate
What is humor?
the liquid in the eye