IGCSE BIOLOGY REVISION [Syllabus 14] The Eye

The structure of the human eye. Main topics:
- Structure & function of the eye
- Pupillary reflex (The pupil size is controlled by the iris. There are two muscles in the iris: Circular and radial. When circular muscles contract, they make the pupil smaller. When Radial muscles contract they make the pupil bigger. These are antagonistic muscles so therefore when one contracts the other MUST relax)
- Accommodation (The lens changes shape depending on the proximity of the object. Closer objects require extra effort to focus and therefore the lens gets THICKER. This is called accommodation. Ciliary muscles CONTRACT to allow the lens to get larger / thicker to look at things up close. Looking at things in the distance will RELAX the ciliary muscles and make the lens THINNER).

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[abdulshukoorpms]

Pupil Reflex:
easier way to remember:
CCRRB
(Circular muscles Contract Radial muscles Relax in Bright light)

Just the opposite for dim light
CRRCD
(Circular muscles Relax Radial muscles Contract in Dim light)

[marwanaser]

Omg you're back! Welcome back!!! Please don't stop making videos, keep on going you're saving lives!

[kanmanisakthivel]

You're the best, within a very short time you cover a whole unit and you're explanation is very much understandable, thank you very much and don't stop until u complete the whole syllabus

[miakahlon]

You're truly amazing. I don't know how much I can thank you. You've helped me with so many topics that I wasn't able to understand. Appreciate your hard work and effort and will stay as a dedicated subscriber throughout. Thanks again.

[n.s]

Please finish the syllabus, that would be really helpful! 💜😅

[tumia]

Your videos are so helpful. I appreciate your hardwork. Is it possible for you to finish the syllabus before the may/june board exam??

[nasrinhaque]

11 may is my biology o level and you this video literally saved me😭

[crytichacker]

What's your name professor? I am an IGCSE student and I think you teach me so precise and tried your best to use simple words to explain each of the exterior and interior parts of an eye. I understand that teaching is so hard to teach students to let them understand the syllabus of the Biology. Thanks for putting a lot of effort on it and I'll look at it a several times just to make sure that I remember it easily.

[steelomens]

Really appreciate the videos THANK YOU!!

[daliadarkazanli]

thank you so much, you have always helped me with your videos.

[abiramims]

i have a doubt. you said that fovea has high concentrated of cones. so, does it mean that animals such as dogs and cats has less or don't have fovea. bec i hav heard that animals cannot distinguish between colours. pls clear this.

[velocityop]

just remeber CCC, Circular muscles contract to contrict if there is any confusion

[mqnkxy]

Thanks. I was struggling with accommodation and your explanation really helped me understand :))

[von]

hi i appreciate ur hardwork i really do so thank u, but can you also do exam questions and past papers. I can get u past paper or each topic's question from save my exams.

[mohammedal-mandhari]

Helloo
The most important topic ;;; reproduction please, before 20 may which is the day of my IGCSE exams
Plz urgently its the only topic I struggggle with.

[himalnilanka]

So, after someone stares at a bright object for example the sun we g0 blinded for a moment, so during that time what happens in the retina?do we get blind as a saftey procedure so prevent further harm?

[letbealove]

Hi um I have a question..
So does this mean that people who are colour blind have a few number of cones?

[osamatariq]

Can you please cover chapter 15 to 21? I have my exams next week.

[sally]

Hello sir plz continue doing video i need it plz

[anahadsaluja]

Hello please can you upload new topics, only few weeks left. Thank you