Senses Flashcards
What comprises the outer layer of the eye?
Cornea and sclera
What is the cornea?
Transparent dome front surface
Protection and focus of light
What is the sclera?
Fibrous, white surface
Structural support and muscle attachment
What is the uvea?
The middle section of the eye comprising of the pupil, iris, ciliary body and choroid
What is the iris?
Coloured section surrounding pupil
Muscles control pupil size and how much light enters
What is the pupil?
Black centre
Changes shape using muscles in the iris to allow varying amounts of light in
What is the ciliary body?
Ring behind the iris
Muscles control the lens to adjust focus
What is the choroid?
Vascular layer supplying oxygen and nutrients
Absorbs excess light
What structures comprise the inner eye?
Retina, macula and optic nerve
What is the retina?
Thin tissue layer that lines the back of the eye
Abundant photoreceptors that convert light to chemical signals (rods and cones)
What are rods and cones?
Photoreceptor cells found in the retina
Rods detect in dim light and peripheral vision
Cones detect bright light and colour vision
What is the macula?
A small region on the retina with an abundance of cone photoreceptors for central vision and fine detail. The fovea area gives us the sharpest vision
How are electrical signals transmitted from the retina to the brain?
Via the optic nerve - optic chiasma - occipital lobe
What is the lens?
An auxiliary structure behind the iris that focuses light onto the retina. It’s shape is controlled by the ciliary muscles
What is humorus?
Fluid that maintains the shape of the eye and provides nutrients
Aqueous humour is in the front chamber
Vitreous humour is behind the lens
What is the sequence of events which turns light into ‘vision’?
Light enters eye via cornea
Light travels through the pupil (controlled by iris)
Light reaches the lens which changes shape (controlled by ciliary body) to focus on the retina
Light hits cones + rods in retina causing phototransduction to create an electrical signal
Optic nerve carries signal via chiasma to the occipital lobe
What is decussation?
When visual information crosses over at the optic chiasma
(Lateral vision does not cross over)
What is the purpose of taste?
Identify nutritious food
Respond to bodily demand
Recognise harmful food
Create memory to remember the above
Describe the structure of the tongue?
Skeletal muscle covered in mucus membrane
Surface covered in papillae which contain taste buds
Taste buds contain gustatory cells
What are the regions of the tongue?
Apex, body and root
What are the 5 tastes?
Sweet (detect sugar)
Sour (detect acid)
Salty (detect sodium and minerals)
Bitter (detect unpleasant)
Umami (savoury flavour linked to glutamate amino acid)
Describe the structure of the olfaction system?
Olfactory mucosa is covered in a mucus layer
Olfactory mucosa contains olfactory receptor cells with cilia that project into the mucus layer
Olfactory nerve carries electrical signals to the olfactory bulb and onto the brain
How does smell occur?
Odorous chemicals enter the nose and dissolve into the mucus layer
Olfactory cell cilia detect and are stimulated by these chemicals
An electrical signal is created and sent to the brain
What is anosmia?
Loss or altered sense of smell
What is ageusia?
Loss of taste
What is hypogeusia?
Reduced taste