COM S2 Flashcards
Name anatomical parts of the eye.
Conjunctiva, Cornea, Sclera, Choriod, Retina, Iris, Lens, Aqueous and Vitreous Humor, Ciliary Body, Optic Nerve
Give the description and function for the Conjunctiva
Delicate membrane
Covers the surface of the eye and inside eyelids
Protects front part of eye
Give the description and function for the Cornea
Front part of eyeball
Transparent & relatively thick
Refracts light rays as they pass through
Give the description and function for the Sclera
White part of eye
Continuous with cornea but not transparent
Protects eye
Helps maintain shape
Give the description and function for the Choroid
Inside of sclera
Thick, black layer containing blood vessels
Carry oxygen and nutrients to eye & remove carbon dioxide and wastes
Prevents light in eye from reflecting internally
Give the description and function for the Retina
Inner most layer of eye & lines back of eyeball
Contains photoreceptors (rods & cones)
Contains retinal nerve cells – convert incoming light into nerve impulses
Receives light changes into electrical impulses that travel via the optic nerve to the brain
- Allow us to see shape, movement and colour
Give the description and function for the Iris
Coloured part of eye
Ring of muscles with a hole in middle (the pupil)
Controls amount of light entering the eye
Give the description and function for the Lens
Transparent, biconvex protein disc behind the pupil and iris
Focuses light rays onto the retina
Give the description and function for the Aqueous and Vitreous Humor
Aqueous humour
Viscous liquid fills front chamber of eye
Vitreous humour
Jelly-like fills larger back chamber of
Help keep eyeball in spherical shape
Refract light as pass through
Give the description and function for the Ciliary Body.
Connects choroid with lens
Contains suspensory ligaments and ciliary muscles
Suspensory ligaments Hold lens in position
Ciliary muscles Alter shape of lens
Give the description and function for the Optic Nerve
Connects eye to brain
Blind spot: has no photoreceptors and cannot produce an image
Carries nerve signals from retina to visual cortex in brain interprets them as images
First-hand investigation of a mammalian eye to gather first-hand data to relate structures to functions, name an aim.
Aim: To dissect a cow’s eye so that various structures can be identified and related to their function
First-hand investigation of a mammalian eye to gather first-hand data to relate structures to functions, name a method can be summarised.
- Collect dissecting scissors, scalpel forceps, newspaper and eye
- Observe exterior
• 4 muscle attachments move eye from side to side
(Trim off muscle and fat)
• Sclera protects and maintain shape of eye
• Cornea transparent opening that allow light to enter and refract light
• Optic nerve lower back – white cylinder – transmits impulses to visual cortex of brain that then interprets them as an image - Used scalpel to make incision at junction of cornea and sclera
Clear liquid that flows out = aqueous humour (helps eye maintain pressure) - Make incision around circumference of sclera
Jelly-like liquid = vitreous humour (helps eye retain its shape and refract light) - Observe front half of eye
Clear biconcave lump of thick jelly = lens (changes shape to focus) - Iris
Surrounds the lens
Opens and closes to regulate amount of light entering
Associated with ciliary body (set of muscles which change shape of lens) - Back of eye:
Retina = blood vessels (contains rods and cones that detect light and colour) - Behind the retina (ONLY SPECIFIC TO COWS)
Tapetum Bright coloured layer that helps reflect light in dark
Specific to nocturnal animals
Sits in front of choroid layer = prevents internal reflection
First-hand investigation of a mammalian eye to gather first-hand data to relate structures to functions, name a conclusion.
• The structures of the eye relate to its function of admitting light, refracting and focusing it to form an image and converting this to an impulse that is presented to the brain
Identify the limited range of wavelengths of the electromagnetic spectrum detected by humans
- Electromagnetic spectrum = range of wavelengths of electromagnetic radiation
- Can detect wavelengths between 380 and 780 nm of the electromagnetic spectrum
- Range = visible light (what we can only see) colours red, orange, yellow, green, blue, indigo and violent
- Blue-green (500nm) Most effective wave lengths for human eye
Identify the limited range of wavelengths of the electromagnetic spectrum detected by vertebrates
• Can detect different ranges of electromagnetic ranges compared to humans
• Many not able to distinguish colours
• Dogs see similarly to human who is red-green colour blind
• Rattlesnakes have receptors in pits between eye and nostril detect infrared radiation
Helps locate prey (animals radiate heat, a form of infrared radiation)
• Fish and snakes can see longer wavelengths so can detect infrared radiation (heat)
• Birds detect greater wavelength than humans
Some very sensitive to ‘red’ end of spectrum
Can detect infrared radiation ‘ Some can detect UV light – reflected by white and violet-coloured flowers and insects (see below)
Identify the limited range of wavelengths of the electromagnetic spectrum detected by invertebrates
- Can detect different ranges of electromagnetic radiation
- Spiders & Insects (e.g. Bees) see UV light
- Less sensitive to higher wavelengths (red end) of the spectrum
The rattlesnake and the electromagnetic spectrum.
A vertebrate, infra red and visible, wave lengths detected = 850-480 nm
Wave lengths detected by a human?
700-400nm and detected in the visible section of the Electro magnetic spectrum.
The Honey Bee and the electromagnetic spectrum
Invertebrate, detects ultraviolet and visible, wavelengths detected = 700-300nm
Use available evidence to suggest reasons for the differences in range of electromagnetic radiation detected by humans and other animals
- Colour sensitivity is related to the structure of the eye
- Number of types of colour-sensitive cones + sensitivity range = determines colour vision
- Some organisms with compound eyes (e.g. bees) have visual cells sensitive to different ranges of electromagnetic radiation
- Colour vision related to evolution
- Believed that humans and our primate line evolved from nocturnal ancestor our colour vision evolved separately from many of the other placental mammals
Compare the differences in range of electromagnetic radiation in vertebrates with a Rattle snake and a human.
Rattle snake =
Infrared and visible Active at night
Detect infrared from their prey
Allows snake to hunt successfully at night
Human =
Visible Active during day uses colour for perception of objects
Compare the differences in range of electromagnetic radiation of invertebrates with a honey bee and a monarch butterfly
Honey Bee =
UV and visible Can detect ultraviolet markings on flowers that we cannot see
> Patterns guide the insect to pollen or nectar source
Monarch Butterflies =
UV Use UV to navigate in the sky when migrating over great distances
