Biology Exam Review Essay

Biology Exam Review
Layers of eye:
Sclera: white portion of eye, maintains shape.
Iris: coloured portion of the eye.
Pupil: opening in the center of the eye.
Conjunctiva: mucous membrane layer that covers the sclera.
Lacrinal gland: produces tears Lacrinal Duct: is in the inner edge of eye.
Cornea: transparent, nonvascular layer covering the coloured part of the eye.
Choroid: in between retina and sclera. Rich with blood vessels.
Lens: biconvex structure that helps focus the image onto retina. It changes shape.
Ciliary body: each side of lens, has muscles that adjust lens.
Suspensory Ligaments: holds lens in place, helps change the shape of lens.
Retina: layer that changes light into nerve impulses.
Rods: white black or gray light. Cones: color. Bright lights.
Fovea Centralis: where the sharpest image is obtained. CENTRAL VISION.
Optic Nerve: receives impulses from retina and sends it to brain.
Optic disc: does not have any rods or cones. BLIND SPOT.
Aqueous humor: fluid between the pupils and cornea.
Vitreous humor: maintains eye shape; inside the eye ball.
Astigmatism: light rays don’t meet a focal point
Monochromatism: color blindness.
Achromatic Vision: cannot distinguish any color. White black grey.
Cataract: lens in eye becomes progressively cloudy, dead cells in lens.
Conjunctivitis: pink eye, inflammation of conjunctiva.
Glaucoma: disorder due to the increase in intraocular pressure.
Myopia: near sightedness (rays meet before retina) concave
Hyperopia: far sightedness (rays meet past retina) convex
Ocular Melanoma: cancer from melanocytes. Often in people in 60s. caused by increased UV radiation, and symptoms include blur, flashing, shadow, clouding.
Strabismus: eye’s different direction due to weak muscles.
The Nervous System
Synapse: small spaces between neurons. More synapses=slower transmission.
Pre synaptic>release acetycholine messenger>post synaptic>choline sterase.
Insecticides: work by nerve messengers contract but do not relax.
Straighten arm out to release a ball (excitatory)>bend arm back (inhibitory).
Parkinson’s Alzheimer’s Disease: deterioration of the transmitter chemicals.
Gray Matter: brains cells without neurilemma=damage permenant.
Neuron: around 100 billion, cells that conduct nerve impulses.
Action potential: a rapid depolarization of the neurons.
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When the ions are in its place, positive on the outside and negative in the inside, it is Polaraized (polarization).
Depolarization: decreasing of polarization towards zero. When an impulse passes through and the sodium and potassium ions switch over.
Repolarized: it is when the ions move back to its original place.
All or none response: either you feel the impulse or you don’t
Threshold: one’s level of pain it can withstand to feel or not. People develop their own threshold.
Refractory Period: it is when the neuron resists another action potential. It is composed of two parts: the absolute and relative. The absolute refractory period is the first part of the period in which the membrane can not produce an action potential. The relative refractory period is the second part in which it takes a stronger than usual stimulus to trigger an action potential.
Endocytosis: when a cell takes in molecules.
Exocytosis: is when a cell releases molecules from its cell membrane.
Hypothalamus: involved with drives associated with survival such as hunger, thirst, emotion, sex, and reproduction.
Cell organelles:
Nucleus: a large membrane enclosed structure that contains the cell’s genetic material in the form of DNA. It is the control tower.
Cytoplasm: is the portion of the cell outside the nucleus.
Nucleus membrane or envelope: allows things to enter and leave the nucleus.
Nucleolus: this is where ribosomes are made and assembled.
Ribosomes: proteins are assembled on ribosomes.

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