LO: Unit 5 Flashcards
Name the five special senses
The five special senses are olfaction (smell)
gustation (taste)
vision (sight)
audition (hearing)
equilibrium (balance).
Name the organs of taste (gustation).
The organs of taste include taste buds, which are located on the tongue, soft palate, and epiglottis.
Name the organs of smell (olfaction).
The organs of smell include the olfactory epithelium, which is located in the upper part of the nasal cavity.
Describe the location and structures of receptor cells for taste.
The receptor cells for taste are located in taste buds, which are primarily found on the tongue, soft palate, and epiglottis. Each taste bud contains gustatory cells, which are the actual receptor cells for taste. These cells have microvilli that extend into the taste pore, where they come into contact with taste molecules.
Describe the location and structures of receptor cells for smell.
The receptor cells for smell are located in the olfactory epithelium, which is a specialized tissue located in the upper part of the nasal cavity. The olfactory epithelium contains olfactory receptor neurons, which are the receptor cells for smell. These neurons have cilia that extend into the mucus lining the nasal cavity, where they detect odor molecules.
Describe the cellular mechanisms of taste.
In taste (gustation), when a tastant (a chemical that can be tasted) comes into contact with the microvilli of gustatory cells in a taste bud, it binds to receptors on the microvilli. This binding activates a signaling pathway that ultimately results in the release of neurotransmitters, which stimulate sensory neurons connected to the taste bud. These sensory neurons then transmit signals to the brain, where the taste is perceived.
Describe the cellular mechanisms of smell.
In smell (olfaction), odor molecules bind to receptors on the cilia of olfactory receptor neurons in the olfactory epithelium. Each olfactory receptor neuron expresses only one type of olfactory receptor, but different neurons can express different receptors. When an odor molecule binds to its receptor, it activates a signaling pathway that leads to the generation of action potentials in the olfactory receptor neuron. These action potentials are then transmitted along the olfactory nerve to the olfactory bulb in the brain, where the odor is perceived.
Describe the central neuronal pathways of taste.
The central neuronal pathways of taste and smell both involve the transmission of sensory information to higher brain regions for processing and perception.
For taste, the sensory neurons from taste buds project to the brainstem, specifically the nucleus of the solitary tract (NST). From the NST, taste information is relayed to the thalamus and then to the primary gustatory cortex in the insular cortex, where taste perception occurs.
Describe the central neuronal pathways of smell.
For smell, the olfactory receptor neurons project their axons through the cribriform plate to the olfactory bulb, where they synapse with mitral cells and tufted cells. The axons of these cells form the olfactory tract, which projects to several areas in the brain, including the olfactory cortex, the orbitofrontal cortex, and the amygdala. These areas are involved in processing and integrating olfactory information, leading to the perception of smell.
Describe the location and structures of receptor cells for vision.
The receptor cells for vision are located in the retina, which is the light-sensitive tissue lining the inner surface of the eye. The primary receptor cells are called photoreceptors, which come in two types: rods and cones. Rods are responsible for vision in low light conditions and do not detect color, while cones are responsible for color vision and function best in bright light. These photoreceptors contain photopigments that undergo chemical changes when exposed to light, initiating a signaling cascade that ultimately leads to the generation of electrical signals sent to the brain for visual processing.
Describe the cellular mechanisms of vision.
The cellular mechanisms of vision involve the conversion of light into electrical signals that can be processed by the brain. This process primarily occurs in the photoreceptor cells of the retina, known as rods and cones.
When light enters the eye and reaches the retina, it is absorbed by the photopigments in the rods and cones. This absorption causes a chemical change in the photopigments, leading to the activation of a signaling cascade within the photoreceptor cell.
In rods, this signaling cascade leads to the closure of sodium ion channels, which hyperpolarizes the cell and decreases the release of neurotransmitters onto bipolar cells. This reduction in neurotransmitter release signals to the bipolar cells that light is present.
In cones, the process is similar but more complex, involving different types of cones that are sensitive to different wavelengths of light (colors). The activation of different cone types allows for color vision.
The electrical signals generated in the photoreceptor cells are then transmitted to other retinal cells, such as bipolar cells and ganglion cells, before being sent along the optic nerve to the brain for further processing and perception.
Describe the central neuronal pathways for vision.
The central neuronal pathways for vision involve the transmission of visual information from the retina to the visual cortex in the brain for processing and perception.
After the photoreceptor cells in the retina generate electrical signals in response to light, these signals are transmitted to bipolar cells and then to ganglion cells, whose axons form the optic nerve. The optic nerve carries the visual information from each eye to the brain.
At the optic chiasm, some of the fibers from the nasal retina of each eye cross to the opposite side, while others remain uncrossed. This partial crossing allows for binocular vision, where visual information from both eyes is integrated to create a single, three-dimensional image.
After the optic chiasm, the visual information travels along the optic tracts to the lateral geniculate nucleus (LGN) of the thalamus. From the LGN, the visual signals are relayed to the primary visual cortex located in the occipital lobe of the brain. Here, the visual information is processed to extract features such as shape, color, and motion, ultimately resulting in visual perception.
Describe the anatomy of the ear, including the auditory and vestibular systems.
The ear is divided into three main parts: the outer ear, the middle ear, and the inner ear.
Outer ear: The outer ear consists of the pinna (or auricle) and the ear canal (external auditory meatus). The pinna helps collect sound waves and funnel them into the ear canal, which leads to the eardrum (tympanic membrane).
Middle ear: The middle ear is an air-filled space located behind the eardrum. It contains three small bones called the ossicles (malleus, incus, and stapes) that transmit sound vibrations from the eardrum to the inner ear. The middle ear is also connected to the back of the throat by the Eustachian tube, which helps equalize air pressure between the middle ear and the environment.
Inner ear: The inner ear is a complex structure that contains both the auditory and vestibular systems.
Auditory system: The cochlea is the primary structure of the auditory system. It is a spiral-shaped, fluid-filled organ that converts sound vibrations into electrical signals that can be interpreted by the brain. The cochlea contains specialized hair cells that are stimulated by the movement of fluid within the cochlea, which occurs in response to sound waves. These hair cells then transmit electrical signals along the auditory nerve to the brain.
Vestibular system: The vestibular system is responsible for balance and spatial orientation. It includes the vestibule and three semicircular canals, which are fluid-filled structures that detect changes in head position and movement. The semicircular canals detect rotational movements, while the vestibule detects linear acceleration and the orientation of the head with respect to gravity. Hair cells in the vestibular system transduce these movements into electrical signals that are sent to the brain via the vestibular nerve.
Describe the location and structures of receptor cells for hearing and equilibrium.
The receptor cells for hearing and equilibrium are located in the inner ear, specifically in the cochlea for hearing and the vestibular system for equilibrium.
Hearing (Cochlea): The receptor cells for hearing are called hair cells, which are located in the cochlea. The cochlea is a spiral-shaped structure filled with fluid. Inside the cochlea, there are three rows of outer hair cells and one row of inner hair cells. These hair cells are located on the basilar membrane, which runs the length of the cochlea. When sound waves enter the cochlea, they cause the basilar membrane to vibrate, which in turn causes the hair cells to bend. This bending of the hair cells stimulates them to produce electrical signals, which are then sent to the brain via the auditory nerve for processing.
Equilibrium (Vestibular System): The receptor cells for equilibrium are also hair cells, but they are located in the vestibular system, which includes the semicircular canals and the vestibule. The semicircular canals detect rotational movements of the head, while the vestibule detects linear acceleration and the orientation of the head with respect to gravity. In the semicircular canals, hair cells are located within a structure called the ampulla, which contains a gelatinous mass called the cupula. When the head rotates, the movement of the fluid in the semicircular canals causes the cupula to bend, which stimulates the hair cells. In the vestibule, the hair cells are located in the utricle and saccule, which detect linear acceleration and gravity. When the head moves, the movement of the otoconia (small calcium carbonate crystals) in the utricle and saccule stimulates the hair cells, sending signals to the brain via the vestibular nerve.
Describe the cellular mechanisms of hearing and equilibrium.
Hearing:
Sound waves are collected by the outer ear and funneled down the ear canal to the eardrum.
The eardrum vibrates in response to the sound waves, transmitting these vibrations to the middle ear.
The ossicles (malleus, incus, and stapes) in the middle ear amplify and transmit these vibrations to the oval window, a membrane-covered opening that leads to the inner ear.
The vibrations in the oval window cause fluid in the cochlea to move, stimulating the hair cells located on the basilar membrane.
The movement of the hair cells generates electrical signals that are transmitted along the auditory nerve to the brainstem and then to the auditory cortex in the brain, where they are interpreted as sound.
Equilibrium:
The semicircular canals of the vestibular system detect rotational movements of the head.
When the head rotates, the movement of the fluid in the semicircular canals causes the cupula (a gelatinous mass) to bend, stimulating the hair cells located within.
The bending of the hair cells generates electrical signals that are transmitted to the brain via the vestibular nerve, informing the brain about the direction and speed of the head movement.
The utricle and saccule of the vestibule detect linear acceleration and the orientation of the head with respect to gravity.
In the utricle and saccule, the movement of the otoconia (small calcium carbonate crystals) stimulates the hair cells, generating electrical signals that are transmitted to the brain for processing.
