Eye Diseases/Conditions, Senses, Neuron Anatomy, Nervous System Pathways, Neuron Communication

Astigmatism

• Definition: A common vision condition that causes blurred or distorted vision.

• Causes: Irregular shape of the cornea or lens, or an uneven curvature of the eye.

• Symptoms: Blurred vision, eyestrain, headaches, difficulty seeing at night.

• Treatment: Eyeglasses, contact lenses, or refractive surgery.

• Complications: Eye strain, headaches, reduced visual acuity and lazy eye

Retinablastoma

• Definition: Retinoblastoma is a rare form of eye cancer that primarily affects young children.

• Symptoms: White pupil (leukocoria), crossed or misaligned eyes (strabismus), poor vision, eye redness or swelling.

• Causes: Genetic mutation in the RB1 gene, inherited or sporadic.

• Treatment: Enucleation (removal of the affected eye), chemotherapy, radiation therapy, laser therapy.

• Complications: Risk of secondary cancers, vision loss, cosmetic concernss

Amplyopia (lazy eye)

• Definition: A condition where one eye has reduced vision due to abnormal visual development during childhood.

• Causes: Strabismus (misalignment of the eyes/muscle imbalance), refractive errors, cataracts, or eye injuries.

  • One eye has a weak signal to the brain

• Symptoms: Blurred vision, poor depth perception, squinting, or tilting the head.

• Treatment: Patching the stronger eye to force the weaker eye to work, eyeglasses, eye drops, or surgery.

Color blindness

• Color blindness is caused by a deficiency or absence of certain color-sensitive cells in the eyes.

  • cones in retina not developing properly or not developing at all

• Symptoms include difficulty distinguishing between certain colors, especially red and green.

• can cause light sensitivity

• color blind glasses

Cataracts

• Definition: Cataracts are a clouding of the lens in the eye.

  • small bits of protein in lower lens

• causes double vision

• Causes: Aging, injury, certain medications, and medical conditions.

• Symptoms: Blurred vision, sensitivity to light, difficulty seeing at night.

Glaucoma

• Definition: A group of eye conditions that damage the optic nerve, leading to vision loss.

• Symptoms: Gradual loss of peripheral vision, tunnel vision, blurred vision, eye pain or redness.

• more blind spots, loses communication w/brain

• eye pain/blindness

• Complications: Vision loss, blindness, decreased quality of life.

conjunctivitus/ pink eye

• Causes: Viral, bacterial, or allergic reactions

• membrane under the eyelids has blood vessels inflamation

• blurred vision and sensitivity to light

receptive field

Receptive Field:

• Definition: The area of the input space that a neuron is sensitive to.

  • larger field = poorer ability to pinpoint

  • smaller = greater ability to pinpoint sensatoin

nucleus

houses dna and controls cell

dendrites

signals received

mitochondria

power house of the cell

nissl body

makes proteins/ macromolecules

collateral

where axons can branch off

axon

long section of neuron where signal carries

axon hillock

start of impulse propagation

synaptic terminal

signal sent to next cell

synapse

space where a neuron can communicate with another cell

General senses

temperature, pain, touch, pressure, vibration, proprioception (body position relativity)

Special Senses

Smell, taste, vision, hearing, balance

Temperature

recptor - thermoreceptors

• Notice changes fast and adapt quickly

pain

receptor: nociceptors

• common on surface of skin, joints

• receptive field typically large

Touch, pressure, vibration, position (overall)

overall sensory receptor : mechanoreceptors

Touch/pressure/vibration (all)

Tactile receptors

• Often difficult to differentiate between touch, pressure, and vibration

• fine touch vs. crude touch

Pressure (only)

Receptor: Baroreceptors

• typically for autonomic activities, between tissues of the wall of organ & blood vessels

Position (only)

receptor: proprioceptors

• monitors position of joints, tension in tendons and ligaments, and state of muscle contraction

• constant stream of information to your conscious/subconscious

Equlibrium

receptor: hair cells inside inner ear

• on top of hair cells is a gelatinous mask and CaCO3 (otolith) crystals, which push down on hair cells

• when the head tilts, otolith crystals move with gravity and “frees” the hair cells, which upsets one’s equilibrium

hearing

receptor : hair cells

• uses pressure in the form of sound waves and vibrations between hair cells to formulate a sensation

smell

receptor: olfactory'

• receptors can bind to many different odorant molecules

• 800+ receptors in humans

taste

receptor: taste receptors ( sweet, bitter)

• primarily identifies toxins and nutrients

• sweet, bitter, salty, sour, savory (umami)

central nervous system

analyszes sensory information and coordinates output

consists of brain & spinal cord

afferent division —> somatic sensory receptor OR visceral sensory receptor

afferent : sends sensory info to CNS

sometic sensory receptor : from outside envirement

efferent division → somatic OR autonomic

efferent: motor commands

somatic : voluntary actions

autonomic: involuntary actions / naturally occuring

somatic → skeletal muscle

voluntary actions

autonomic →parasympathetic OR sympathetic → smootj/cardiac muscle, glands, adipose tissue

parasympathetic: rest and digest , opposite of sympathetic

Sympathetic: fight or flight

receptors

recieves input

effectors

motor commands through…

action potential

travels through synaptic terminal and depolarizes membrane

calcium channels

open and calcium ions enter

Neurotransmitter vesicles

move to fuse with the ST membrane

Vesicles

release neurotransmitters(NT) through exocytosis to synapse (aka synaptic cleft)

Neurotransmitter →

binds with NT receptor, triggering AP in next cell

Neurotransmitter →

degraded our reabsorbed by NT transporter