Nervous System III: Senses - Hole's Human Anatomy & Physiology

Comprehensive practice questions and answers covering general and special senses, including biology of the eye, ear, taste, and smell based on Hole's Human Anatomy & Physiology, 14th edition.

What are the two major categories of senses and where are their receptors located?

General senses (widely distributed in skin, organs, and joints) and Special senses (confined to structures in the head like eyes, ears, nose, and mouth).

Distinguish between sensation and perception.

Sensation is a feeling that occurs when the brain becomes aware of sensory information, whereas perception is the way the brain interprets that sensory information.

Which type of sensory receptor responds to changes in chemical concentrations?

Chemoreceptors.

Which receptors are specifically sensitive to tissue damage from mechanical, electrical, or thermal energy?

Pain receptors, also known as nociceptors.

What is the result of a sensory receptor being stimulated in terms of membrane potential?

It causes a local change in membrane potential called a graded potential, the intensity of which depends on the stimulus strength.

Explain the process of projection by the cerebral cortex.

It is the process where the brain interprets a sensation as being derived from certain receptors and projects it back to the apparent source, allowing a person to pinpoint the region of stimulation.

Define sensory adaptation.

The ability to ignore unimportant or continuous stimuli due to decreased response from receptors (peripheral) or along CNS pathways (central).

What are the three groups of general senses?

Exteroceptive senses (body surface), Interoceptive/Visceroceptive senses (visceral changes like blood pressure), and Proprioceptive senses (muscle and joint changes).

Which mechanoreceptors are responsible for detecting fine touch, texture, and distinguishing between two points on the skin?

Tactile (Meissner’s) corpuscles.

What are the temperature ranges for warm and cold receptors?

Warm receptors are sensitive to temperatures above $25^{\circ}\text{C}$ ($77^{\circ}\text{F}$) and unresponsive above $45^{\circ}\text{C}$ ($113^{\circ}\text{F}$). Cold receptors are sensitive between $10^{\circ}\text{C}$ ($50^{\circ}\text{F}$) and $20^{\circ}\text{C}$ ($68^{\circ}\text{F}$).

What is referred pain?

Visceral pain that feels as if it is coming from a part of the body other than the source, such as heart pain felt in the left shoulder, due to common nerve pathways.

Compare Fast pain fibers and Slow pain fibers.

Fast pain (A-delta) fibers are myelinated and conduct at up to $30\,\text{m/sec}$ (sharp pain), while Slow pain (C) fibers are unmyelinated and conduct at up to $2\,\text{m/sec}$ (dull, aching pain).

What are three pain-inhibiting substances produced by the body?

Enkephalins, Serotonin, and Endorphins.

What is the function of Muscle spindles?

They are stretch receptors in skeletal muscles that initiate stretch reflexes causing muscle contraction.

Define synesthesia.

A condition where the brain interprets a stimulus for one sense as coming from another (e.g., "the paint smelled blue").

How does the sense of smell relate to the sense of taste?

The sense of smell provides $75\text{-}80\%$ of the sense of taste.

Name the five primary taste sensations.

Sweet, Sour, Salty, Bitter, and Umami.

Which three cranial nerves conduct taste impulses to the medulla oblongata?

Facial nerve (VII), Glossopharyngeal nerve (IX), and Vagus nerve (X).

What are the three tiny bones of the middle ear (auditory ossicles)?

Malleus (hammer), Incus (anvil), and Stapes (stirrup).

What is the purpose of the tympanic reflex?

Muscle contractions (tensor tympani and stapedius) that occur during loud sounds to lessen vibration transfer and prevent damage to hearing receptors.

What is the function of the Auditory (eustachian) tube?

It connects the middle ear to the throat and helps maintain equal pressure on both sides of the tympanic membrane.

Distinguish between the osseous and membranous labyrinths of the inner ear.

The osseous labyrinth is a bony canal in the temporal bone filled with perilymph; the membranous labyrinth is a tube within it filled with endolymph.

What is the organ for the sense of hearing located on the basilar membrane?

The Spiral Organ, also known as the Organ of Corti.

Compare Conductive Deafness and Sensorineural Deafness.

Conductive deafness ($95\%$ of cases) involves interference with sound conduction to the inner ear (e.g., ear wax, ossicle injury); Sensorineural deafness involves damage to the cochlea or auditory nerve (e.g., loud music, tumors).

Differentiate between static and dynamic equilibrium.

Static equilibrium senses head position when not moving (receptors in the vestibule); dynamic equilibrium senses rotation and movement of the head/body (receptors in semicircular canals).

What are otoliths and where are they found?

Calcium carbonate crystals found on the surface of the macula in the vestibule that shift with gravity to help sense head position.

Name the four layers of the eyelid (palpebrae).

Skin, muscle, connective tissue, and conjunctiva.

What is the antibacterial component found in tears?

Lysozyme.

Name the three tunics of the eyeball and their components.

Outer/Fibrous (Cornea and Sclera), Middle/Vascular (Choroid coat, Ciliary body, and Iris), and Inner/Nervous (Retina).

What is accommodation in vision?

The change in lens shape to view close objects; the lens thickens for close vision and thins/flattens for distant objects.

Contrast Rods and Cones.

Rods provide colorless vision in dim light and produce outlines; Cones provide color vision and sharp images in bright light.

What is the visual purple pigment found in rods and what does it decompose into?

Rhodopsin; it decomposes into Opsin and Retinal in the presence of light.

Name the three light-sensitive pigments in cones and the colors they respond to.

Erythrolabe (red), Chlorolabe (green), and Cyanolabe (blue).

Define Stereoscopic vision.

The perception of distance, depth, height, and width resulting from two slightly different retinal images from the eyes.

What is presbyopia?

An age-related visual problem involving the loss of lens elasticity, which decreases accommodation.