BIO 180 - Human Anatomy and Physiology I - Unit V Notes (copy)

Special Senses: Olfaction

• Olfactory Receptors:

  • Olfactory Glands (Bowman’s):

    • Produces mucus that dissolves odorants.

  • Olfactory Stem/Basal Cells:

    • Regenerate olfactory receptor cells.

  • Olfactory Epithelia:

    • Contains olfactory receptor cells.

  • Olfactory Cilia:

    • Hair-like structures that bind odorants.

  • Lamina Propria:

    • Connective tissue layer supporting olfactory epithelium.

  • CN I - Olfactory Nerve, Bulb, & Tract:

    • Transmits olfactory information to the brain.

Special Senses: Gustation

• Taste Buds:

  • Papillae:

    • Structures on the tongue that contain taste buds.

  • Gustatory Epithelial Cells:

    • Taste receptor cells.

  • Gustatory Hairs:

    • Microvilli that project into the taste pore and bind tastants.

  • Taste Pore:

    • Opening in the taste bud that allows tastants to enter.

  • Types of Lingual Papillae:

    • Filiform (no taste buds, texture).

    • Fungiform (taste buds).

    • Circumvallate (taste buds).

  • Types of Taste/Flavors:

    • Sweet, salt, sour, bitter, umami, and water.

Olfactory and Gustatory Pathways

• Olfactory pathway involves the olfactory receptors in the nasal cavity sending signals to the olfactory bulb, then to the olfactory cortex without passing through the thalamus.

• Gustatory pathway involves taste receptors on the tongue sending signals to the medulla oblongata, then to the thalamus, and finally to the gustatory cortex.

Special Senses: Vision - Accessory Structures of the Eye

• Accessory Structures:

  • Eyebrows/Lashes:

    • Protects the eyes from debris and sunlight.

  • Eyelids:

    • Lateral and medial canthus, tarsal glands.

    • Protects and lubricates the eye.

  • Conjunctiva:

    • Lines the eyelids and covers the anterior surface of the eye.

  • Lacrimal Apparatus:

    • Lacrimal glands, lake, puncta, canaliculi, caruncle, nasolacrimal duct.

    • Produces and drains tears.

  • 6 Extrinsic Eye Muscles:

    • Controls eye movement.

Structures of the Eye

• Fibrous Layer:

  • Sclera (white of the eye).

  • Cornea (transparent anterior portion).

• Vascular Layer/Uvea:

  • Choroid (blood-rich layer).

  • Ciliary Body (controls lens shape).

  • Iris (controls pupil size).

  • Pupil (opening in the iris).

• Inner/Neural Layer/Retina:

  • Ora Serrata (serrated edge of the retina).

  • Pigmented Layer (absorbs light).

  • Neural Layer (contains photoreceptors).

  • Photoreceptors (rods and cones).

  • Bipolar Cells.

  • Ganglion Cells.

  • Optic Disc (blind spot).

  • Macula Lutea (area of high visual acuity).

  • Fovea Centralis (area of sharpest vision).

  • Lens (focuses light).

  • Anterior Segment/Cavity:

    • Anterior Chamber.

    • Posterior Chamber.

    • Aqueous Humor.

    • Canal of Schlemm (drains aqueous humor).

  • Posterior Segment/Cavity:

    • Vitreous Humor.

Events Converting Light into Neural Signal

• Photoreceptors:

  • Rods (black and white vision).

  • Cones (color vision).

• Photopigments:

  • Light-sensitive molecules in photoreceptors.

• Retinal:

  • Light-absorbing molecule in photopigments.

• Phototransduction:

  • Process by which light is converted into an electrical signal.

• Accommodation:

  • Adjustment of the lens to focus on objects at different distances.

• Refraction:

  • Bending of light as it passes through the cornea and lens.

• Adaptation:

  • Adjustment of the eye to changes in light intensity.

• Color Vision (Cones) vs. Black and White Vision (Rods):

  • Cones: Color vision in bright light.

  • Rods: Black and white vision in dim light.

Visual Pathway

• Optic disc → optic nerve (CN II) → optic chiasm → lateral geniculate nuclei → optic radiation → occipital lobes

Special Senses: Hearing - Structures of the Ear

• Outer Ear:

  • Auricle/Pinna (collects sound waves).

  • External Auditory/Acoustic Canal/Meatus (transmits sound waves).

  • Ceruminous Glands (produces earwax).

• Middle Ear:

  • Tympanic Membrane (eardrum).

  • Oval and Round Window (membranes connecting middle and inner ear).

  • Malleus, Incus, Stapes (ossicles that transmit vibrations).

  • Auditory Tube (Eustachian tube, equalizes pressure).

  • Tensor Tympani (muscle that dampens loud sounds).

  • Stapedius (muscle that dampens loud sounds).

• Inner Ear:

  • Bony Labyrinth (outer bony shell).

  • Membranous Labyrinth (inner membrane-bound tubes).

  • Perilymph (fluid between bony and membranous labyrinths).

  • Endolymph (fluid within membranous labyrinth).

  • Vestibule (saccule, utricle - balance).

  • Semicircular Canals (anterior, posterior & lateral - balance).

  • Cochlea (hearing).

  • Macula (sensory receptor for static equilibrium).

  • Semicircular Duct (contains endolymph).

  • Ampulla (swelling at the end of semicircular canal).

  • Crista Ampullaris (sensory receptor for dynamic equilibrium).

  • Cupula (gelatinous structure covering hair cells).

  • Scala/Ducts:

    • Cochlear Duct (Scala Media).

    • Vestibular Duct (Scala Vestibuli).

    • Tympanic Duct (Scala Tympani).

  • Vestibular Membrane.

  • Basilar Membrane.

  • Organ of Corti (contains hair cells).

  • Hair Cells (sensory receptors for hearing).

  • Spiral Ganglia.

Terms Related to Sound

• Frequency:

  • Number of sound waves per second (measured in Hertz).

• Pitch:

  • Perception of frequency.

• Volume/Intensity:

  • Amplitude of sound waves (measured in decibels).

• Resonance:

  • Amplification of sound waves.

Auditory and Equilibrium Pathways

• Auditory pathway involves sound waves causing vibrations in the tympanic membrane, which are transmitted through the ossicles to the oval window, creating pressure waves in the cochlear fluid that stimulate hair cells in the organ of Corti, leading to electrical signals sent to the auditory cortex.

• Equilibrium pathway involves hair cells in the vestibule and semicircular canals detecting changes in head position and movement, sending signals to the vestibular nuclei and cerebellum to coordinate balance and posture.