Week 5 Flashcards
what is the palpebral fissure ?
the palpebral fissure is the opening between the upper and lower eyelids, it is the area between the eyelids that allows the eye to be exposed to the environment.
what is the lateral commissure ?
this is the outer corner of the eye, where the upper and lower eyelids meet.
what is the medial commissure ?
this is the inner corner of the eye, where the upper and lower eyelids meet.
what is the lacrimal caruncle ?
the lacrimal caruncle is the small, pinkish tissue found at the medial commissure. it contains sweat glands and sebaceous glands.
what is the sclera ?
the sclera is the white part of the eye that surrounds the iris. it is the tough, fibrous outer layer that provides structure and protection to the eyeball.
what is the pupil ?
the black circular opening in the center of the iris. it controls the amount of light that enters the eye and it can change size in response to light conditions.
describe in detail, the lacrimal apparatus.
the lacrimal apparatus is the system that produces, stores, and drains tears.
components:
1. lacrimal glands: the lacrimal glands are located just beneath the eyebrow. these glands produce lacrimal fluid/tears.
2. lacrimal ducts: the lacrimal ducts are responsible for draining the tears from the lacrimal glands and distributing the tears over the cornea and conjunctiva.
3. lacrimal puncta: there are tiny openings called lacrimal puncta located at the inner corners of the upper and lower eyelids. they are the first step in draining tears from the eye.
4. lacrimal canaliculi: after tears enter the puncta, they travel through small channels called lacrimal canaliculi that direct tears towards the lacrimal sac.
5. lacrimal sac: the lacrimal sac collects the tears from the canaliculi before they are drained further down into the nasolacrimal duct.
6. the nasolacrimal duct is a tube that extends from the lacrimal sac down through the side of the nose. its main function is to drain tears into the nose.
what is the role of tears ?
lubrication: they keep the eye moist preventing dryness and irritation
protection: they contain lysozyme which helps fight bacteria
nourishment: tears provide essential nutrients to the cornea, which doesn’t have its own blood supply
cleaning: tears help wash away dust and debris
what are the components of a typical tear ?
water, electrolytes, proteins: one being lysozyme which is an enzyme that has antibacterial properties, lipids to help reduce evaporation, mucus
identify the extrinsic eye muscles ?
there are 6 in total which attach to the sclera and control eye movement in various directions.
superior rectus: this muscle is located at the upper part of the eye and moves the eye upwards.
inferior rectus: this muscle is located at the lower part of the eye and moves the eye downwards.
lateral rectus: this muscle is on the outer side of the eye and moves the eye outwards: laterally.
medial rectus: this muscle is located on the inner side of the eye and moves the eye inwards: medially.
superior oblique: this muscle rotates the eye downward and inward.
inferior oblique: this muscle rotates the eye upwards and outward
the internal structures of the eye can be grouped into ?
3 main layers: the fibrous layer, the vascular layer, and the inner layer.
what makes up the fibrous layer ?
the fibrous layer forms the outer protective layer of the eye. it is made up of two main structures: cornea and sclera.
what is the cornea ?
the cornea is a transparent, dome shaped structure that forms the front part of the eye. its function is to bend light entering the eye and direct it towards the retina.
anterior vs posterior pole ?
the anterior pole is the point in the front of the eye where the cornea and sclera meet. the posterior pole is the point in the back of the eye where the retina attaches to the optic nerve.
what is the vascular layer of the eye ?
the vascular layer of the eye contains the blood vessels that help nourish the eye and consists of 3 main parts: iris, ciliary body, and ciliary zonule/suspensory ligament.
what is the iris ?
the iris is the colored part of the eye. it controls the size of the pupil regulating the amount of light that enters the eye.
what is the ciliary body ?
the ciliary body is a ring shaped structure located behind the iris. it consists of ciliary muscle and ciliary processes.
ciliary muscle: controls shape of lens for focusing. it also produces the aqueous humor.
what is the inner layer ?
the inner layer is also known as the retina. it is responsible for detecting light and converting it into neural signals which are then sent to the brain for visual processing. it includes the macula lutea and the optic disc.
what is the macula lutea ?
the macula lutea is a small yellowish region located at the centre of the retina. it contains a high concentration of CONES which are responsible for sharp details and color detection.
what is the fovea centralis ?
the fovea centralis is a small depression in the centre of the macula where the highest concentration of cones is located.
what is the optic disc ?
the optic disc is a small area on the retina where the optic nerve exits the eye. it clacks photoreceptor cells so it does not detect light.
clearly distinguish between rods and cones.
rods: primarily responsible for night vision and low light conditions. they do not detect color. allow us to see shapes and movement in low light environments.
cones: responsible for color and sharp central vision and function vest in bright light and provide detailed high resolution vision necessary for tasks like reading, recognizing faces, and seeing in daylight.
RODS: found mainly in the peripheral areas of the retina.
CONES: found mainly in the central part of the retina, especially the fovea centralis.
- way more rods than cones
what are bipolar cells ?
bipolar cells are intermediate neurons in the retina that transmit signals from the rods/cones to the ganglion cells.
what are ganglion cells ?
ganglion cells are the final output neurons, they receive electrical signals from the bipolar cells and process these signals to form the final visual information that is sent to the brain via the optic nerve.
describe in detail, the signalling pathway that results in phototransduction, starting with rhodopsin and ending with activation of the ganglion cells.
- light hits rhodopsin in the photoreceptor cells, causing retinal to change from 11-cis to all-trans form, activating rhodopsin.
- the activated
distinguish between emmetropic, myopic, and hyperopic eyes.
emmetropic eye: normal or ideal eye where light entering the retina is perfectly focused onto the retina.
myopic eye: nearsightedness: eye is too long or cornea is too curved.
- causes blurry vision for distant objects, near vision is clear.
- can be corrected with concave lenses
hyperopic eye:
farsightedness: eye is too short or the cornea is too flat.
- causes blurry vision for close objects, distant vision is clear.
- can be corrected with convex lenses.
what is rhodopsin and retinal ?
rhodopsin is a light sensitive protein found in the retina of the eye, specifically in rod cells, which is responsible for vision in low light conditions.
retinal is a molecule that acts as the light absorbing molecule within rhodopsin, meaning when light hits retinal, it changes shape, triggering a signal that initiates the process of vision.
describe in detail, the olfactory epithelium.
the olfactory epithelium is a specialized tissue located in the upper part of the nasal cavity that plays a crucial role in the sense of smell.
describe the arrangement of a typical taste bud.
list the 5 flavours.
sweet, sour, salty, bitter, umami
describe in detail, the signalling pathway that results in olfaction.
describe the signalling pathway that results in taste.
