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Questions and Answers
What characteristic differentiates rods from cones in the retina?
What characteristic differentiates rods from cones in the retina?
Which of the following structures is responsible for the highest visual acuity?
Which of the following structures is responsible for the highest visual acuity?
What is the primary role of the aqueous humor in the eye?
What is the primary role of the aqueous humor in the eye?
What causes senile cataracts in the eye?
What causes senile cataracts in the eye?
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Which wavelength of light corresponds to the color red in the visible spectrum?
Which wavelength of light corresponds to the color red in the visible spectrum?
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Which type of lingual papillae is characterized by having no taste buds?
Which type of lingual papillae is characterized by having no taste buds?
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Which of the following structures primarily protects the eye from foreign matter?
Which of the following structures primarily protects the eye from foreign matter?
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Which taste sensation is classified as pleasant and savory, primarily associated with glutamate?
Which taste sensation is classified as pleasant and savory, primarily associated with glutamate?
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What is the main function of gustatory epithelial cells?
What is the main function of gustatory epithelial cells?
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What characteristic is specific to the bulbar conjunctiva?
What characteristic is specific to the bulbar conjunctiva?
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Study Notes
Special Senses
- Olfaction (smell) involves olfactory receptors responding to airborne chemicals.
- Olfactory organs are located in the nasal cavity.
- Olfactory organs are made of two layers: olfactory epithelium and lamina propria.
- Olfactory epithelium contains olfactory sensory neurons, supporting cells, and basal epithelial cells.
- Lamina propria contains areolar tissue, blood vessels, and nerves, and olfactory glands.
- Olfactory reception begins with odorants binding to G-protein-coupled receptors, creating a generator potential.
- Afferent fibers collect into 20 or more bundles.
Gustation (Taste)
- Gustation is the sense of taste.
- Gustatory epithelial cells are taste receptors found in taste buds.
- Taste buds are distributed on the superior surface of the tongue and pharynx.
- Different types of lingual papillae contain taste buds: filiform, fungiform, vallate, and foliate.
- Taste buds contain basal epithelial cells.
- Gustatory epithelial cells extend microvilli through taste pores.
- Receptors are replaced every 10 days.
- Sensory information travels to the thalamus, and gustatory complex of the insula.
Accessory Structures of the Eye
- Eyelids (palpebrae) continue the skin and blink to keep the eye lubricated and clean.
- Palpebral fissure is the gap between upper and lower eyelids.
- Medial canthus and lateral canthus connect the eyelids.
- Eyelashes are hairs to prevent foreign matter.
- Tarsal glands and lacrimal caruncle produce secretions.
Internal Eye Structures
- The fibrous layer is the outer layer of the eyeball, including the sclera and cornea.
- The vascular layer (uvea) contains the iris (which controls pupil size) and ciliary body.
- The neural layer (retina) contains photoreceptors (rods and cones).
- The ciliary body and lens divide the eye into anterior and posterior cavities.
- The aqueous humor circulates in the anterior cavity.
- The vitreous body is a gel-like substance in the posterior cavity.
- The lens focuses light on the retina.
Physiology of Vision
- Rods detect light/dark.
- Cones provide color vision and are concentrated in the fovea centralis.
- Photoreceptors generate electrical signals which are processed in the visual cortex.
- Structures like the optic disc, and optic nerves play an important role in the visual pathway.
- Visual acuity is the clarity of vision.
Equilibrium
- The vestibular complex provides sensations of head position and movement through the utricle and saccule in the vestibule, and semicircular canals.
- Hair cells in the vestibule detect linear acceleration and gravity.
- Hair cells in the semicircular canals detect rotational acceleration.
- Messages travel through the vestibulocochlear nerve (VIII) and synapse within the vestibulocochlear nuclei.
- Sensory information is integrated, and commands are sent to motor nuclei for smooth movement of eyes, head, and neck to maintain equilibrium.
Hearing
- Sound waves vibrate the tympanic membrane.
- Auditory ossicles transmit vibrations to the internal ear.
- Vibrations of the basilar membrane cause hair cells to vibrate against the tectorial membrane.
- Information about sound is transmitted to the auditory cortex in the brain through the auditory pathway.
- The spiral ganglion contains the cell bodies of bipolar sensory neurons that monitor cochlear hair cells, and afferent fibers send information.
Endocrine System Overview
- Endocrine cells and tissues produce hormones.
- Hormones control and coordinate body processes.
- Mechanisms of intercellular communication, such as direct, paracrine, and autocrine communication
- Different classes of hormones include amino acid derivatives, peptide hormones, and lipid (steroid) derivatives
Pituitary Gland
- The pituitary gland is a major endocrine gland located in the sella turcica.
- It has an anterior and a posterior lobe.
- The anterior lobe (adenohypophysis) releases hormones under hypothalamic control.
- The posterior lobe (neurohypophysis) releases hypothalamic hormones.
- The hypothalamus regulates the pituitary gland via releasing and inhibiting hormones.
Thyroid Gland
- The thyroid gland is located inferior to the thyroid cartilage of the larynx.
- It consists of two lobes connected by an isthmus.
- Follicle cells secrete thyroid hormones (T3 and T4), and C cells produce calcitonin
- Thyroid hormones regulate metabolism.
Parathyroid Glands
- Embedded in the posterior surface of the thyroid gland, the parathyroid glands produce parathyroid hormone (PTH), which increases blood calcium levels.
- PTH stimulates osteoclasts, enhances calcium reabsorption in the kidneys, and stimulates calcitriol formation
Adrenal Glands
- Paired adrenal glands are located above each kidney.
- The adrenal cortex secretes steroid hormones (mineralocorticoids, glucocorticoids, and androgens).
- The adrenal medulla secretes catecholamines (epinephrine and norepinephrine).
Pancreas
- The pancreas is both an exocrine and endocrine gland.
- Exocrine portion produces digestive enzymes.
- Endocrine portion (islets of Langerhans) produces hormones that regulate blood glucose levels.
- Alpha cells produce glucagon (increases blood glucose).
- Beta cells produce insulin (lowers blood glucose).
- Delta cells produce somatostatin.
Other Endocrine Organs
- Many other organs have secondary endocrine functions.
- Kidneys, heart, intestines, thymus, and gonads secrete hormones to influence various physiological processes.
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Description
Explore the fascinating world of olfaction and gustation. This quiz covers the anatomy and physiology of the senses of smell and taste, detailing their respective receptors and mechanisms. Test your knowledge on how these sensory systems function and their significance in perception.
