232 exam2 Flashcards
Describe the structure of the olfactory epithelium
The olfactory epithelium contains the olfactory sensory neurons, supporting cells, and regenerative basal epithelial cells (stem cells). It covers the inferior surface of the cribriform plate, the superior portion of the perpendicular plate, and the superior nasal conchae of the ethmoid. The second layer, the underlying lamina propria, consists of areolar tissue, numerous blood vessels, and nerves.
Describe and understand the process of olfactory reception and the pathway to the brain.
Begins with afferent fibers leaving the olfactory epithelium that collect into 20 or more bundles. These bundles penetrate the cribrifome plate of the ethmoid bone to reach the olfactory bulbs, where the first synapse occurs. Efferent fibers from the nuclei elsewhere in the brain also innervate neurons of the olfactory bulbs. Leave the olfactory bulb to the olfactory cortex of the cerebral hemispheres, the hypothalamus, and portions of the limbic system.
Describe the structure of taste buds and taste receptors
inside the folds of the 3/4 papillae contain taste buds. The taste pore receives the molecule of food particle where it lands on the taste hairs or microvilli of the gustatory epithelial cell. In between the gustatory epithelial cells is the transitional cells. Basal epithelial cells are in the beach ball structure as stem cells if the gustatory epithelial cells are damaged or needs to be replaced.
Describe and locate the four types of lingual papillae
filiform papillae
fungiform papillae
vallate papillae
foliate papillae
Describe the gustatory pathways, including which cranial nerves innervate which lingual papillae
The gustatory pathway starts with taste buds, which are innervated by cranial nerves VII (facial), IX (glossopharyngeal), and X (vagus).
Describe the four primary and two lesser known taste sensations
Primary taste sensation: sweet, salty, sour, bitter
The two lesser known taste sensations: umami and water
Identify the accessory structures of the eye and explain their functions.
eyelids, palpebral fissure, medial angle, lateral angle, eyelashes, tarsal glands, lacrimal caruncle, conjunctiva, palpebral conjunctiva, bulbar conjunctiva, lacrimal apparatus, fornix, lacrimal gland, lacrimal puncta, lacrimal canaliculi, nasolacrimal duct
the internal structures of the eye
Fibrous layer:
Sclera - covers most of the ocular surface. Consists of a dense fibrous connective tissue containing both collagen and elastic fibers. thickest over the posterior surface and thinnest over the anterior surface. Six extrinsic eye muscles insert on the sclera, blending their collagen fibers with those of the fibrous layer.
Cornea - Structurally continuous with the sclera. the border between the two is called the corneoscleral junction (corneal limbus).
Describe the internal structures of the eye in the fibrous layer and explain their functions
Sclera - covers most of the ocular surface. Consists of a dense fibrous connective tissue containing both collagen and elastic fibers. thickest over the posterior surface and thinnest over the anterior surface. Six extrinsic eye muscles insert on the sclera, blending their collagen fibers with those of the fibrous layer.
Cornea - Structurally continuous with the sclera. the border between the two is called the corneoscleral junction (corneal limbus). Consists of primarily of a dense matrix containing multiple layers of collagen fibers, organized so as not to interfere with the passage of light. no blood vessels. obtain oxygen and nutrients by diffusion from the tears. has numerous free nerve endings.
Describe the internal structures of the eye in the Vascular layer and explain their functions
Iris - is a pigmented, flattened ring structure, that is visible through the transparent corneal surface. Contains blood vessels, pigment cells (melanocytes), and two layers of smooth muscle (pupillary muscles). When the muscles contract it changes the diameter of the pupil. The two muscles are: Dilator pupillae and sphincter pupillae. The muscles are controlled by the autonomic nervous system. Sympathetic activation causes the pupils to dialate and Parasympathetic causes it to constrict.
Ciliary body - where the iris attaches on the periphery at the anterior portion to the ciliary body. Which is a thickened region that begins deep to the corneoscleral junction. It extends posteriorly to the level of the ora serrata (the serrated anterior edge of the neural layer of the retina). Mainly consists of ciliary muscles (a ring of smooth musclesthat projects into the interior of the eye.epithelium covers the muscle which has numerous folds called ciliary processes. ciliary zonule is a ring of fibers that attaches the lens to the ciliary processes. This holds the lens posterior to the iris allowing any light passing through the pupil also passes through the lens.
Choroid - is a vascular layer that separates the fibrous layer and the inner layer posterior to the ora serrata. It is covered by the sclera and attached to the outermost layer of the retina.
Describe the internal structures of the eye in the Inner layer and explain their functions
Pigmented layer of the retina - absorbs light that passes through the neural layer, preventing light from bouncing back through the neural layer and producing visual “echoes.”
Neural layer - Cellular organization: several layers of cells. The inner layer of the retina contains supporting cells and neurons that do preliminary processing and integration of visual information. The outermost part, closest to the pigmented layer of the retina, contains photoreceptors (the cells that detect light). The photoreceptors are rods and cones. Rods do not discriminate among colors of light. Highly sensitive to light, they enable us to see in dimly lit spaces. Cones give us sharper, clearer, color vision.
Optic disc: part of the neural layer goes to optic nerve (II). Has no photoreceptors.
Describe and understand the organization of the retina
The retina is what is considered the inner layer. it consists of the pigmented layer which has the cells that prevent light from bouncing through the neural layer. Cellular organization is the photoreceptors which is the rod and the cones. These converge to the bipolar cells which then in turn converge to the ganglion cells to send back to brain for processing and interpretation.
Understand the relationship between ciliary muscle contraction/relaxation and lens shape in reference to focal distance.
The lens is held in place by the ciliary zonule that originates at the ciliary body. Smooth muscle fibers in the ciliary body act like sphincter muscles. When the ciliary muscle contracts, the ciliary body moves toward the lens, thereby reducing the tension in the ciliary zonule. The elastic capsule then pulls the lens into a rounder shape that increases the refractive (bending) power of the lens. This enables it to bring light from nearby objects into focus on the retina. When the ciliary muscle relaxes, the ciliary zonule pulls at the circumference of the lens, making the lens flatter.
Understand visual acuity (normal vs. abnormal vision)
is rated by comparison to a “normal” standard. The standard vision rating of 20/20 is defined as the level of detail seen at a distance of 20 feet by a person with normal vision. That is, a person with a visual acuity of 20/20 sees clearly at 20 feet what should normally be seen at 20 feet. Vision rated as 20/15 is better than average, because at 20 feet the person is able to see details that would be clear to a normal eye only at a distance of 15 feet. Conversely, a person with 20/30 vision must be 20 feet from an object to discern details that a person with normal vision could make out at a distance of 30 feet.
Describe the anatomy of rods and cones
Rods do not discriminate among colors of light. Highly sensitive to light, they enable us to see in dimly lit rooms, at twilight, and in pale moonlight. Rods have a rod shape the inside the the top of the ride is pancake shaped lipid bilayer. Cones give us color vision. Cones give us sharper, clearer images than rods do, but cones require more intense light. Similar to the rod the cones has a shaped top, but is shaped cone like. Inside the cone is a wave back and forth of lipid bilayer.
Understand the activities of the dark current
Sodium entry though gated channels produces dark current.
The plasma membrane in the outer segment of the photoreceptor contains chemically gated sodium ion channels. In darkness these gated channels are kept open in the presence of cGMP (cyclic guanosine monophosphate), a derivative of high-energy compound guanosine triphosphate (GTP). Because the channels are open, the membrane potential is approximately -40mV, rather than -70mV (which is the typical resting state of neurons). At the -40mV membrane potential, the photoreceptor is continuously releasing neurotransmitters (in this case, glutamate) across synapses at the inner segment. the inner segment also continuously pumps sodium ions out the cytosol.
Describe and understand the steps in photoreception
Photoreception is the ability to absorb photons.
When it is dark and the eyes are closed the rods and cones are creating an inhibiting current to the bipolar cells. This is with a chemically gated channel with cGMP. When the light hits the rod or cone the organelle of Rhodopsin which has a protein called opsin bound to the pigment retinal. The 11-cis retinal changes shape in light to 11-trans retinal. The opsin activates and in turn activates transducin then phosphodiesterase. The phosphodiestrase breaks down the cGMP to CMP removing the chemical keeping the sodium gated channel open. This inactivates the rods and cones allowing the bipolar neuron to activate and send a signal.
Describe and understand the process of bleaching and regeneration.
1) On absorbing light, retinal changes to a more linear shape. This change activates the opsin molecule.
2) Opsin activation changes the Na+ permeability of the outer segment, and this changes the rate of neurotransmitter release by the inner segment at its synapse with a bipolar cell.
3) Changes in bipolar cell activity are detected by one or more ganglion cells. The location of the stimulated ganglion cell indicates the specific portion of the retina stimulated by the arriving photons.
4) After absorbing a photon, the rhodopsin molecule begins to break down into retinal and opsin. This is know as bleaching.
5) The retinal is converted to its original shape. This conversion requires energy in the form of ATP.
6) Once the retinal has been converted, it can recombine with opsin. The rhodopsin molecule is now ready to repeat the cycle. The regeneration process takes time. After exposure to very bright light, photoreceptors are inactivated while pigment regeneration is under way.
Understand the phenomenon of color vision
An object appears to have a particular color when it reflects photons from one portion of the visible spectrum and absorbs the rest. Color discrimination takes place through the integration of information arriving from all three types of cones: Blue, Green, and Red. We also perceive black and white through the rods that can only detect light and dark.
Understand how vision changes in dark and light adapted states
Dark-adapted state is a state in which the pigments are fully receptive to stimulation and almost all the visual pigments will have recovered from photobleaching. Think when the coming in from outside on a bright day and not being able to see very well since everything seems so dark.
Light-adapted state when the rate of bleaching is balanced by the rate at which the visual pigment reassemble. Think going from a dark room to bright outside, where it is unbearably bright.
Describe and understand the monitoring of rods by M-cells and cones by P-cells
M cells are the fairly large ganglion cells that monitor rods. They provide information about the general form of an object, motion, and shadows in dim lighting. Since there is so much convergence occurring the activation of an M cell indicates that light has arrived in a general area rather than at a specific location.
P cells is the ganglion cells that monitor cones. The process of visual stimuli from cones is different because of their lack of convergence. In the fovea centralis, the ratio of cones to ganglion cells is 1:1.
Describe and follow the pathways of impulses of the optic nerve to the visual cortex (including all stops along the way)
Describe the structures of the external and middle ears and explain how they function
External ear consists of auricle or pinna that surrounds the passageway of the external acoustic meatus, or auditory canal. Along the acoustic meatus are cerminous glands that are integumentary glands that secrete a waxy material called cerumen (or earwax). The auditory canal ends with the tympanic membrane.
The middle ear or tympanic cavity is an air-filled chamber separated from the external acoustic meatus and the tympanic membrane. The middle ear communicates with both the nasopharynx and the auditory tube. The middle ear contains the auditory ossicles. These three bones are the malleus, the incus, and stapes. Also the middle ear contains the tensor tympani which is a short ribbon of muscle originating on the petrous part of the temporal bone and the auditory tube, and inserting on the “handle” of the malleus (which is controlled by trigeminal nerve V). Also the Stapedius muscle is innervated by the facial nerve VII. Contractions of the stapedius pulls on the stapes, reducing its movement at the oval window.
Describe and understand the relationship of the bony labyrinth, perilymph, membranous labyrinth, and endolymph
bony labyrinth is filled with perilymph, which inside the perilymph is the membranous labyrinth. Inside the membranous labyrinth is filled with the endolymph.
Describe what components of the inner ear make up the vestibular complex
The vestibular complex provides with equilibrium sensations. It is the semicircular canals (anterior, lateral, and posterior), the ampullary crest with amullae, maculae, endolympatic sac, and vestibule (which contains the utricle and saccule). The semicircular ducts and the vestibule have receptors called hair cells.
Describe the structure of the cochlea
The cochlear duct or scala media, lies between a pair of perilyphatic chambers, or scalae: the scala vestibuli (or vestibular duct) and the scala tympani (or tympanic duct). These three ducts are encased by the bony labyrinth everywhere except the oval window and the round window. These ducts are a continous spiral tubes. The hair cells are loctaed in the an structure called the spiral organ (organ of Corti). The sensory structure sits at the basilar membrane (separates the chochlear duct from the scala tympani. The hair cells are arranged in a series of longitudinal rows. Their sterocilia are in contact with the overlying tectorial membrane. This membrane is firmly attached to the inner wall of the cochlear duct.
Describe and understand the relationship of the semicircular canals, ampulla, endolymph, cupula, and the sense of three-dimensional movement of the head.
The semicircular canals are arranged to be able to sense gravity and movement in the three directions and a combination of the three. Each simicircular duct contains an ampula, an expanded region that contains the receptors. The region in the wall of the ampulla that contains the hair cells is the ampullary crest. And each cell is bound to an amupllary cupla (a gelatinous structure that extends the full width of the smulla. The endolymph flows through the membranous labyrinth moving the cupula allowing the sense of three-dimensional movement of the head.
Describe and understand the relationship of the utricle, saccule, otolith, and the sense of gravitational pull and linear acceleration.
The vestibule contains the utricle and saccule. The hair cells of this area provide position and linear movement sensations. There are densley packed calcium carbonate crystals called otolith. When they move over the cluster of hair cells in the utricle and saccule called maculae, can sense gravity and movement. Depending if the crystals are together pressing down on the maculae or moving across it (sensing movement). and the sense of gravitational pull and linear acceleration
Describe the pathway for equilibrium sensations
Hair cells of the vestibule and semicircular ducts are monitored by sensory neurons located in adjacent vestibular ganglia. Sensory fibers from these ganglia form the vestibular nerve, a division of the vestibulocochlear nerve (VIII). These fibers innervate neurons within the pair of vestibular nuclei at the boundary between the pons and the medulla oblongata.
The reflexive motor commands issued by the vestibular nuclei are distributed to the motor nuclei for cranial nerves involved with eye, head, and neck movements (CN III, IV, VI, and XI). Instructions descending in the vestibulospinal tracts of the spinal cord adjust peripheral muscle tone and complement the reflexive movements of the head or neck
Describe and understand the structure of the spiral organ and how it relates to hearing
The hair cells of the cochlear duct are located in the spiral organ. The spiral organ is the spiral-shaped cochlea. This sensory structure sits on the basilar membrane. The hair cells are arranged in a series of longitudinal rows. They lack kinocilia, and their sterocilia are in contact with the overlying tectorial membrane. This membrane is firmly attached to the inner wall of the cochlear duct. As the basilar membrane moves the hair cells move over the tectorial membrane causing stimulus that is sent to the nerve fibers.
Describe and understand the processes involved in hearing
1) Sound waves arrive at tympanic membrane.
2) Movement of the tympanic membrane displaces the auditory ossicles.
3) Movement of the stapes at the oval window produces pressure waves in the perilymph of the scala vestibuli.
4) The pressure waves distort the basilar membrane on their way to the round window of the scala tympani.
5)Vibration of the basilar membrane causes vibration of hair cells against the tectorial membrane.
6) Information about the region and intensity of stimulation is relayed to the CNS over the cochlear nerve.
Describe the pathway of hearing sensations.
1) Stimulation of hair cells at the specific location along the basilar membrane activates sensory neurons.
2) Sensory neurons carry the auditory information in the cochlear nerve to the cochlear nucleus on that side.
3)Information ascends from each cochlear nucleus to the superior olivary nuclei of the pons and the inferior colliculi of the midbrain.
4) The inferior collciculi direct a variety of unconscious motor responses to sounds.
5) Ascending auditory information goes to the medial geniculate body.
6) Projection fibers then deliver the information to specific locations within the auditory cortex of the temporal lobe.
Describe and understand the four types of intercellular communication and give examples
Direct Communication occurs between two cells of the same type, and the cells must be in extensive physical contact.
Paracrine Communication is when communication between cells involve the release and receipt of chemical messages within a single tissue.
Autocrine communication occurs when the messages affect the same cells that secrete them, and the chemicals involved are autocrines. (ei prostaglandins secreted by smooth muscle cells to cause contraction of those cells.)
Endocrine Communication occurs when the endocrine system uses chemical messengers called hormones to relay information and instructions between cells in distant portions of the body. endocrine cells release these hormones in one tissue, and they are then transported in the bloodstream and distributed throughout the body to their target cells.
Identify the major organs/tissues of the endocrine system
Hypothalamus
Pituitary Gland
Thyroid gland
Adrenal glands
Pancreas (Pancreatic Islets)
Pineal gland
Parathyroid Glands
Identify the 3 classes of hormones
Amino acid derivatives (biogenic amines)
Peptide hormones - glycoproteins, and short polypeptides and small proteins.
Lipid derivatives - eicosanoids and steroid hormones
Describe the major parts and regions of the pituitary gland
Anterior lobe: pas tuberalis ( the largest and most anterior portion of the pituitary gland), pars distalis (which wraps around that adjacent portion of the infundibulum) and pars intermedia (a narrow band bordering the posterior lobe). They receive RH or IH from the hypothalamus to release the hormone it needs to release.
posterior lobe (neurohypophysis) contains axons of the hypothalamic neurons.
Identify the hormones produced and secreted by the anterior lobe, along with their target organ, effects, and any hypothalamic control.
Thyroid-Stimulating Hormone (TSH)
Adrenocroticotropic Hormone (ACTH)
Gonadotropins: Follicle-Stimulating Hormone (FSH) and Luteinizing Hormone (LH)
Prolactin (PRL)
Growth Hormone (GH)
Melanocyte-Stimulating Hormone (MSH)
Identify the hormones secreted from the posterior lobe, along with their target organ, effects, and location in hypothalamus where produced.
Antidiuretic Hormone (ADH)
Oxytocin (OXT)
Discuss and understand the renin-angiotensin system for regulating blood pressure and blood volume.
RAAS
