The Human Eye and Brain Function

The Eye

The eye is a spherical eyeball.
Sclera: The white, thick coat covering the back and sides of the eyeball.
Cornea: The transparent front of the eyeball that lets light in.
Iris: The colored part of the eye, a muscle ring that controls pupil size.
Pupil: A hole in the middle of the iris that adjusts to control light entry.
Lens: Focuses light by changing shape via attached ligaments.
Retina: The inner layer containing light receptor cells.
Optic Nerve: Sends messages from the retina to the brain.
Blind Spot: Area where the optic nerve leaves the retina, lacking receptor cells.
Image Formation: Light rays are bent (refracted) by the cornea and lens to focus on the retina, forming an image.

Short-sightedness (myopia):
- Problem: Image focuses in front of the retina because the eyeball is too long.
- Correction: Concave lenses spread light rays before they enter the eye.
Long-sightedness (hyperopia):
- Problem: Image focuses behind the retina because the eyeball is too short.
- Correction: Convex lenses bend light rays inwards before they enter the eye.

Brain Composition: Contains about 100 billion nerve cells (neurons), each connected to approximately 10,000 others.
Coordination: The brain sorts information received from receptors, decides on actions, and sends messages to muscles and organs.
Functions: Memory, intelligence, emotions, personality.
Cerebrum: The largest part of the brain, responsible for sense information processing, decision-making, and memory storage.
Cerebellum: Controls balance and coordination of movement.
Brain Stem (Medulla): Controls breathing and heart rate.
Learning and Memory: Efficient information storage (tidiness) in the brain aids retrieval.