Anatomy and Physiology I chapter 12 (text/assesment questions + prelab/lab)
How do cochlear implants work? Watch the Biodigital below to assist you in addressing this question.
A cochlear implant is a small, complex electronic device that can help to provide a sense of sound. People who are profoundly deaf or severely hard-of-hearing can get help from them. The implant consists of two parts. One part sits on the outside of the body, behind the ear. A second part is surgically placed under the skin. The sounds comes in from microphone which then processed, The sound passes to the transmitter which transmit signal across the skull. Implant receiver passes the signal to cochlea which stimulates the auditory nerve.
Jane is in the lab analyzing receptive fields of two skin areas. She found one receptive field with a diameter of 2 cm. The other receptive field is much smaller, measuring 0.8 cm. She thinks that larger receptive field will give precise sensory information. Explain to Jane about receptive fields and their relationship with precision in the processing of sensory information.
An area of the skin with smaller receptive field suggests that there are a large number of sensory receptors and therefore the sensation is much more precise compared to the area with fewer sensory receptors. In the areas with larger receptive fields, the smaller number of sensory neurons may have extensive branches to occupy a wider area.
Which fiber type has the slowest conduction velocity to the CNS? Select an answer and submit. For keyboard navigation, use the up/down arrow keys to select an answer. Aα Aβ Aδ C
C A(alpha)
Middle - Vascular Layer:
Choroid: the most posterior part of the vascular layer, the choroid is a blood-rich tunic containing dark pigment to help prevent the scattering of light once it has entered the eye; the anterior-most portion of the choroid is modified to form the ciliary body and iris Ciliary Body: smooth muscle structure that attaches to the lens Iris: the opening of which is called the pupil; the iris dilates and constricts to increase or decrease the diameter of the pupil allowing more or less light to enter the eye
Inner ear:
Cochlea: the structure that transmits sound waves through its fluid-filled chambers; tiny hair cells (receptor cells) process sound according to frequency and pitch and generate nerve impulses that will navigate the auditory nerve pathway to the auditory cortex Semicircular canals: helps to maintain static equilibrium and senses the head's position when the body is still Vestibule: maintains dynamic equilibrium and senses the head's position, rotation, and movement of the body
Sensory adaptation refers to ______. the modality of a sensory receptor receptive field the ability of sensory neurons to respond to stimulation without end the receptors becoming less responsive in the presence of a constant stimulus
Correct Answer: the receptors becoming less responsive in the presence of a constant stimulus
Accessory Structures of the Eye:
Eyelids: involved in the protection of the eye Extrinsic Eye Muscles: attaching to the outer surface of the eye, these muscles produce gross eye movements making it possible to follow a moving object with just your eyes and not your whole head Lacrimal Apparatus: consisting of the lacrimal duct and gland, it is located above the lateral end of the eye; the gland continuously releases dilute salt secretions, aka tears, onto the anterior surface of the eye that are drained by the ducts into the nasal cavity Lacrimal secretions contain antibodies and lysozyme (an enzyme that helps to destroy bacteria) that cleanses, moistens, and protects the eye from possible infection Ever wonder why you get a runny nose when you have a tiny something in your eye? The secretions from the lacrimal apparatus increase in order to destroy potentially harmful substances from entering into the deeper structures of the eye. These secretions empty into the nasal cavity giving you the runny nose.
Perception
Humans are constantly bombarded with billions of sensory inputs from inside and outside our bodies—the temperature outside, the noises around us, the position of our joints in space, and much more. It is not possible to be consciously aware of all this information, so we selectively pay attention to the fraction of information that might indicate an immediate threat. This is known as perception. One thing that is impossible to ignore is pain.
Where does the light go once it enters the eye? Follow the Biodigital to help you answer this question.
Light enters the eye and is focused by the lens on the retina. The lens is a flexible structure that changes shape in order to focus images on the back of the retina. Once focused on the retina, the retina processes the image and converts it into nerve signals that can be perceived by the brain. The blind spot in the eye: no vision when light is centered on the blind spot as it is the point of exit of visual information from the retina to the optic nerve.
Why do cough drops make your throat feel cool?
Menthol in cough drops activates the TRPA1 channel, generating the sensation of coolness when the temperature of throat has not changed
Tunics of the Eye:
Outermost - Fibrous Layer: Sclera: thick connective tissue, the "white of the eye"; protective in nature Transparent Cornea: the central portion of the fibrous layerthe cornea is well supplied with nerve endings, mostly pain fibers it is often considered the "window" of the eye as it allows light to enter into the deeper structures for processingthe only tissue in the body that can be transplanted from one person to another without the issue of rejection due to its lack of blood vessels (the immune system has no access)
Parkinson's disease patients commonly describe insects crawling over their faces. What does this tell you about perception?
Parkinson's disease patients commonly describe insects crawling over their faces. What does this tell you about perception?
Why do some sensory cells never adapt to incoming stimulus?
Sensory cells do not adapt to cellular damage to ensure that a person determines the cause and seeks help to repair it.
Sound incoming to the ear is translated to electrical impulses that must be sent to the brain for processing. Where do these electrical impulses go? Use the song in the following video to help you review this complicated pathway.
The electrical impulses enter from cochlea, and into cochlear nucleus and into superior olivary complex which goes into the nucleus of the lateral lemniscus and then inferior colliculus and medial geniculate body and then auditory cortex in temporal lobe.
What did you learn from the video? List 3 points learned about the visual system.
The video covered visual nerve pathways from eyes to the brain. In the eyes we have a lens which sees it and flips it upside down. It will go to temporal side. The are nasal and temporal visual fibers. Nasal fibers cross at optic chiasm while temporal don't. temporal fibers handle stuff on opposite side.
Summary
This chapter covers how general sensations (touch, pain, pressure, movement, acceleration) are detected by the body and the nature of the cells that do so. These sensory cells transduce (change) physical information from the world into a form understandable by neurons that then relay that information to the CNS.
Middle ear:
Tympanic cavity: air-filled compartment within the temporal bone where the auditory ossicles are located Auditory ossicles: the malleus, incus, and stapes - tiny bones that move in response to the vibrations of the tympanic membrane, allowing for the transmission of sound waves from the outer ear to the fluid-filled inner ear Oval window: the stapes abuts this structure vibrating against it effectively transferring the sound waves to the fluids within the inner ear Ever wonder why a soar throat sometimes leads to an ear infection or achy ears can lead to a sore throat? The middle ear and throat communicate through the eustachian (auditory tube). This air-filled structure equalizes the pressure on either side of the tympanic membrane but also allows for the transmission of infection from one area to another.
Match the following receptor types to their sensory modality. baroreceptors proprioceptors nociceptors tactile receptors
baroreceptors=pressure proprioceptors=body position nociceptors=pain tactile receptors=touch
the ________ is the fluid-filled inner ear consisting of receptor (hair) cells that are involved in auditory processing
cochlea
The are highly concentrated in the periphery of the retina facilitate peripheral vision whereas the are highly concentrated in the retina's center and are charged with processing color.
rods cones
The simplest sensory receptors are ______. sensory nerve endings of unipolar neurons encapsulated nerve endings of unipolar neurons specialized cells of unipolar neurons specialized cells of bipolar neurons
sensory nerve endings of unipolar neurons
Arrange the following structures in the sensory pathway in the correct order. sensory receptor dorsal root ganglion dorsal root thalamus cerebral cortex
sensory receptor dorsal root ganglion dorsal root thalamus cerebral cortex
The is the only tissue in the body that evades the immune system.
transparent cornea
the _______ is an air-filled compartment where the _________ are located
tympanic cavity; auditory ossicles
Sort the structures of the eye to reflect the pathway of light from the retina into the eye en route to the cerebral cortex for processing.
- retina - optic nerve - optic chiasm - optic tract - optic disc - cerebral cortex
Where does sound go once it leaves the ear?
Auditory nerve: transmits electrical impulses from the inner ear to the brainstem where it is then taken to the thalamus; Thalamus: transmits the auditory information to the auditory cortex
Muscle spindles are __________. proprioceptors pressure receptors touch receptors osmoreceptors
Correct Answer: proprioceptors
Which of the following channels open at temperatures above 34°C? Select all that apply. TRPA1 TRPV1 TRPV2 TRPV3 TRPV4 TRPM8
Correct Answers: TRPV1 TRPV2 TRPV3 TRPV4
Sensory receptors use which of the following as they respond to a stimulus? modality location intensity duration
Correct Answers: modality location intensity duration
Sensation of sharp, acute pain is most likely transmitted along which of the following fibers? C fibers Aß fibers A∂ fibers B fibers
Correct Answer: A∂ fibers
True or False: Visceral organs have more pain receptors than anywhere else in the body. True False
Correct Answer: False Explanation There are fewer nociceptors in the abdominal organs.
Which of the following are found within mucous membranes? free nerve endings Merkel cells Meissner's corpuscles Krause's corpuscles Ruffini corpuscles
Correct Answer: Krause's corpuscles
Which signs and symptoms in the initial injury period can be attributed to impairment or disruption caused by the spinal cord injury? Justify your answer.
Artificial ventilation was required, suggesting possible involvement of phrenic nerve which supplies the diaphragm. The initial injury and inflammation in the cervical region may have interrupted the efferent stimulation of the diaphragm. Additionally, the local swelling may have caused the compression throughout the area thus interrupting both afferent and efferent pathways causing numbness and paralysis.
Sort the structures of the eye to reflect the pathway of light from its entrance into the eye en route to the retina. Aqueous humor Cornea Iris and Pupil Lens Vitreous humor
Aqueous humor Cornea Iris and Pupil Lens Vitreous humor
Why are icepacks commonly used on bruises?
Below 10° C, cold receptors do not detect cold temperature but instead bring about an anesthetic effect.
A 10-year-old boy is brought to the clinic by his mother because of a strange lump in his right brachial region. His medical history (as related by his mother) includes extreme clumsiness, broken bones, burns, and various cuts and scrapes over the past two years. In the physical exam, the deformity in the right brachial area is easily moved and subsequent x-ray confirms a fracture. The physical examination also reveals scars around his mouth, and the tip of his tongue is missing. Poking the patient's skin behind his knee with a needle evokes no response. What is likely wrong with the patient? His proprioceptors are absent. His mechanoreceptors are absent. His chemoreceptors are non-functional. He has no functional nociceptors.
Correct Answer: He has no functional nociceptors.
If there is a logarithmic relationship between stimulus intensity and action potential frequency in sensory neurons, how much will the action potential rate increase if the stimulus intensity increases by 100? It will stay the same. It will double. It will triple. It will decrease by 50%.
Correct Answer: It will double. Explanation A stimulus intensity of one would result in a graded potential of zero, but a stimulus intensity of 100 would result in a graded potential of two (because the log10 of one is zero and the log10 of 100 is two). Therefore if the stimulus intensity increases by 100, the action potential rate will double.
Which of the following detect can detect vibrations? free nerve endings Meissner's corpuscles Merkel cells
Correct Answer: Meissner's corpuscles
Which of the following sensory receptors are the encapsulated receptors that are found just beneath the epidermis in the dermal papillae in the non-hairy parts of the skin such as the lips and the finger tips? Merkel's discs Meissner's corpuscles Ruffini's nerve endings hair root plexuses
Correct Answer: Meissner's corpuscles
Touch and pressure are sensed by the following receptors except one. Identify the receptor that is not associated with touch and pressure sensation. Meissner's corpuscles Merkel cells Ruffini corpuscles Osmoreceptors Pacinian corpuscles
Correct Answer: Ruffini corpuscles
A 55-year-old male undergoes a neurological exam that indicates loss of pain and temperature sensitivity, vibratory sense, and proprioception in both his legs. These symptoms could be due to which of the following speculations? a tumor in the fiber tract of medial lemniscal pathway in the sacral spinal cord a tumor in the fiber tract of lateral spinothalamic pathway in the thoracic region of the spinal cord a tumor in the postcentral gyrus a large tumor in the sacral dorsal horn
Correct Answer: a tumor in the postcentral gyrus
Adaptation to a sensory stimulus produces __________. decreased sensation when a stimulus is removed increased sensation when a stimulus is removed decreased sensation when a stimulus is constantly applied increased sensation when a stimulus is constantly applied
Correct Answer: decreased sensation when a stimulus is constantly applied
Referred pain ______. is caused by over-excitation of spinal cord interneurons involved in pain transmission is caused by cross-talk between nociceptors occurs when pain is perceived in an area outside of where the cell damage occurred occurs when thermoreceptors are over-stimulated by chemicals found in peppers
Correct Answer: occurs when pain is perceived in an area outside of where the cell damage occurred
The process by which sensory information is interpreted in a meaningful form is known as ______. sensation perception conduction transduction
Correct Answer: perception
Which of the following neurons connect the spinal cord to the thalamus in the anterolateral pathway? first-order neuron second-order neuron third-order neuron fourth-order neuron
Correct Answer: second-order neuron
Pacinian corpuscles are examples of __________. thermoreceptors nociceptors chemoreceptors tactile receptors
Correct Answer: tactile receptors
A 67-year-old woman is in the doctor's office complaining of numbness on the left side of her body. She also has difficulty moving her left arm and her left leg. Further tests at the doctor's office reveal that she is unable to distinguish between a coin and a paper clip using her left hand when her eyes are closed and cannot feel vibrations of a tuning fork. Pinpricking resulted in duller pain on the left side than the right. Two days after her doctor's visit, she called the doctor's office with burning pain on the left side even with gentle touching. The doctor is suspecting a lesion along one of the sensory pathways. The location of the problem is occurring at the __________. right half of the medulla cerebral cortex peripheral nerves of the left leg and left arm thalamus right half of the spinal cord above C5
Correct Answer: thalamus Explanation Further investigation revealed that this patient had a lesion in the thalamus. A lesion in the thalamic nucleus could result in somatosensory loss. A lesion in the right half of the medulla might interrupt the medial lemniscus causing some of the symptoms, but the spinothalamic tract would be unaffected. A lesion in the cerebral cortex could affect one of the body parts such as the left leg or the left arm but not both as they are widely spread out within the somatosensory cortex. Peripheral nerves are ruled out because peripheral polyneuropathies are bilaterally symmetrical. (Application question)
The second-order neuron in an ascending sensory pathway is found ______. within the thalamus within the spinal cord or brainstem within the dorsal root ganglion within the cerebral cortex
Correct Answer: within the spinal cord or brainstem
Sensory Receptor Physiology
Sensory receptors are neurons that are activated in classical ways—by the opening of ion channels which causes depolarization of the cell membrane. They also possess the property of becoming less responsive in the face of constant stimulus—adaptation. Some receptors are rapidly adapting (phasic receptors), others slowly adapting (tonic receptors). Adaptation is a process by which sensory cells avoid fatigue and remain responsive to a change in a stimulus. Sensory receptors also differ in their receptive field—the area of skin or surface area covered by a single sensory cell. Stronger stimuli produce action potentials at a higher frequency. As the intensity of a stimulus increases, more sensory units are activated in a process known as recruitment.
Mechanoreceptors ______. Select all that apply. are part of general sensation are part of special sensation are part of both general and special sensation are widely distributed throughout the body
are part of general sensation dare widely distributed throughout the body
Sort the structures of the ear to reflect the pathway of sound through the ear en route to the cerebral cortex for processing. auricle external auditory meatus tympanic membrane auditory ossicles cochlea auditory nerve thalamus
auricle external auditory meatus tympanic membrane auditory ossicles cochlea auditory nerve thalamus
Mechanoreceptors detect ______. Select all that apply. Multiple answers:Multiple answers are accepted for this question changes in the cell membrane movement of cilia temperature changes cell damage
changes in the cell membrane movement of cilia cell damage
Review the basic anatomical structures of the eye using the Biodigital that follows. What is the function(s) of each structure that is labeled?
cornea-is a clear covering of tissue that aids in the focus of light into the eye. aqueous humor- The aqueous humor is a transparent fluid that fills the front of the eye and aids in its shape maintenance. iris-is the colorful portion of the eye that regulates the quantity of light that enters the eye pupil-is the dark center of the eye through which light enters. vitreous humor-is a translucent substance that fills the back of the eye and aids in its shape maintenance. retina-is a layer of light-sensitive cells located in the back of the eye that turns light into electrical signals that are then transmitted to the brain.
the _________ is a canal that carries sound waves to the tympanic membrane
external auditory meatus
Where are the smallest sensory cell receptive fields found in the body? lower back behind the knee fingertips on the forehead
fingertips
Your patient is experiencing difficulty reading. You suspect what condition? astigmatism myopia hyperopia
hyperopia
The controls the dilation and constriction of the pupil.
iris
The produces tears (secretions) that enable the eye to be flushed of microbes.
lacrimal apparatus
Match the sensory receptor to the stimulus it detects.
mechanoreceptor body position osmoreceptors solute concentration of fluids thermoreceptor changes in temperature nociceptor cell damage
Your patient complains that he is experiencing difficulty hearing, pain in his ear, and dizziness. You suspect an infection impacting: outer ear inner ear middle ear
middle ear
Sort the structures of the eye to reflect the pathway of light from the retina into the eye en route to the cerebral cortex for processing.
retina optic nerve optic chiasm optic tract optic disc cerebral cortex
Match the structures of the eye with their correct description. sclera-the "white" of the eye; protective in nature iris-pigmented region of the eye; the pupil is at its center optic disc-blind spot fovea centralis=the area of the retina with the greatest visual acuity
sclera-the "white" of the eye; protective in nature iris-pigmented region of the eye; the pupil is at its center optic disc-blind spot fovea centralis=the area of the retina with the greatest visual acuity
Your patient's chief complaint is that she is only able to see objects within her "nasal" visual field. You inform her that this is 'tunnel vision' that may be due to a tumor impacting the visual field pathway. Upon analysis of the MRI you confirm a pituitary tumor that is impacting your patient's
visual filed
How do infections of the middle ear disrupt hearing? Watch the Biodigital below to help you answer this question.
A middle ear infection, also called acute otitis media (AOM), is the infection and inflammation of the middle ear, often accompanied by fluid behind the tympanic membrane (eardrum). \n \nAOM is typically caused by a viral infection arising from another infection, such as an upper respiratory tract infection or the flu. The infection affects the tiny ossicles (bones) of the middle ear, surrounding tissue behind the eardrum, and may also spread to the inner ear. \n \nPatients with a middle ear infection often experience pain and diminished hearing, with redness or bulging of the tympanic membrane. As the ear infection progresses, the eardrum may become perforated (torn), and the patient may experience increased pain and fluid discharge.
Using your knowledge of summation at the postsynaptic cell, explain why a weak stimulus that triggers action potentials infrequently may not be conducted all the way to the central location to be perceived but instead may be lost during their passage through the sensory pathways.
A small change in temperature, for example, may trigger an action potential or two at the sensory receptor level but while it is being conducted along a sensory pathway, the stimulus may not be sufficient enough to allow summation of excitatory postsynaptic potentials, a step that is required to generate a new action potential in the postsynaptic neuron. Thus, we will never be able to learn about this mild change in temperature.
What are some symptoms of inner ear infections? Why are inner ear infections typically harder to treat than middle ear infections? Watch the Biodigital below to assist you in addressing these questions.
An inner ear infection, also called labrynthitis, is the infection and inflammation of the inner ear or nerves that connect the inner ear to the brain (vestibular and cochlear nerves). Inner ear infection is caused by a viral or bacterial infection, often arising from an existing middle ear infection. Patients with an inner ear infection often experience diminished hearing, problems with balance, dizziness, or vertigo. Difficulty to treat inner ear infections are experienced due to the difficulty in accessing the inner ear structures.
What is astigmatism? Briefly discuss the symptoms of the condition and possible treatments. Review the Biodigital below to help you answer this question.
Astigmatism is a condition in which the cornea tends to be oval-shaped (instead of round) leading to blurred vision. Astigmatism is characterized by impaired vision at all distances, headaches, eyestrain, and squinting. Astigmatism can be treated with eyeglasses, contact lenses, and refractive surgery.
A 63-year-old female presents to the hospital's dialysis clinic for dialysis. During a routine workup of the patient while receiving dialysis, the charge nurse notices that the woman has no soft tissue associated with her big toe. Palpation of the skin reveals that the skin covers bone and no other tissues. When the nurse asks the patient if she has noticed anything going on with her, the patient replies, "I haven't felt my feet in years." The patient is also obese and is being treated for hypertension, hyperlipidemia, and hyperglycemia. Diabetes over time may lead to neuropathy, and abnormal or poor sensations. Why was the patient unable to feel her feet? damage caused by hypertension genetic mutation affecting her ability to feel pain diabetic neuropathy had destroyed the nerves over time advanced age
Correct Answer: diabetic neuropathy had destroyed the nerves over time Explanation
The medial lemniscus is part of the ______. anterolateral pathway dorsal column pathway reticulospinal pathway first-order cell
Correct Answer: dorsal column pathway Explanation The axons in the dorsal column terminate in the nuclei of the medulla, where each synapse with interneurons. The interneurons from each one of the two nuclei, nucleus gracilis or nucleus cuneatus, cross the midline of the medulla and then continue to ascend the brain stem as a bundle called the medial lemniscus.
Loss of proprioceptive sensation in a patient with damage to the dorsal column is ______ the loss of pain sensation in the same patient. greater than same as less than
Correct Answer: greater than
Visceral pain __________. causes relaxation of nearby skeletal muscles resembles fast pain shows rapid adaptation is poorly localized
Correct Answer: is poorly localized
The edges of structures are emphasized by ______. lateral inhibition range fractionation signal/noise averaging logarithmic compression ' .
Correct Answer: lateral inhibition Explanation Cells that are activated the most inhibit the output of cells activated to a lesser degree, which increases edge resolution
A patient suffering from severe pain in his right leg undergoes ventrolateral cordotomy. Which specific tract is targeted by the neurosurgeon to offer relief of pain in this patient? left ventral spinothalamic tract right lateral spinothalamic tract left dorsal column left lateral spinothalamic tract
Correct Answer: left lateral spinothalamic tract Explanation The lower half of the body, such as the trunk and the lower limbs, form the lateral spinothalamic tract. Because the pain is felt on the right side, it is the left lateral spinothalamic tract that must be targeted. The lateral spinothalamic tract is part of the anterolateral pathway which conveys pain and temperature information in the spinal cord to higher centers of the brain.
Which of the following receptors become activated by the presence of a physical force? chemoreceptor thermoreceptor nociceptor mechanoreceptor
Correct Answer: mechanoreceptor Explanation Mechanoreceptors, which deal with mechanical stress and detect fluctuations in pressure and gravity, changes in cell volume and shape, position, touch, itch, and movement.
The distinct characteristic that makes one sensation different from others is called its __________. perception modality generator potential receptor potential
Correct Answer: modality
The distinct characteristic that makes one sensation different from others is called __________. perception modality receptive field generator potential
Correct Answer: modality Explanation Sensory modality is when each sensory receptor is optimized to respond to one specific type of stimulus at a much lower threshold than for other types of stimuli.
Which of the following two types of sensory receptors are free nerve endings? nociceptors and thermoreceptors thermoreceptors and olfactory receptors nociceptors and tactile receptors root hair plexuses and Merkel cells
Correct Answer: nociceptors and thermoreceptors
he cell bodies of the first-order neurons in the anterolateral spinothalamic pathway are located in the __________. postcentral gyrus medulla oblongata anterior grey horns of the spinal cord posterior root ganglia
Correct Answer: posterior root ganglia
Which of the following statements regarding the determination of the intensity of the stimulus is true? The magnitude of receptor potentials increases with increasing stimulus intensity. The magnitude of action potentials increases with increasing stimulus intensity. The frequency of action potentials increases with increasing stimulus intensity.
Correct Answers: The magnitude of receptor potentials increases with increasing stimulus intensity. The frequency of action potentials increases with increasing stimulus intensity.
Match the following mechanoreceptors with their property (slow or fast adapting). 1 Free nerve endings 2 Merkel cells 3 Meissner's corpuscles 4 Krause's corpuscles 5 Ruffini corpuscles 6 Pacinian corpuscles
Correct Answers: 1 slow 2 slow 3 rapid 4 rapid 5 slow 6 rapid
Free nerve endings ______. Select all that apply. Multiple answers:Multiple answers are accepted for this question can detect temperature are polymodal are rarely found in the skin detect sound in the ear
Correct Answers: can detect temperature are polymodal
Nociceptors can detect which of the following stimuli? mechanical thermal chemical
Correct Answers: mechanical thermal chemical Explanation Because nociceptors respond to tissue damage, any physical trauma involving mechanical stress like cutting , thermal injury such as burning and chemical injury can stimulate nociceptors.
Which of the following sensations are relayed via the dorsal column pathway? pain proprioception temperature touch vibration
Correct Answers: proprioception touch vibration
Types of Sensory Receptors
General sensory receptors are classified by their location, what they are sensitive to, and their structure. Location refers to whether these receptors are in the skinExteroceptors - situated near the surfaces of the body; they respond to stimuli from the external environment; detect touch, pressure, pain, and temperature.Interoceptors - located deep in the body(e.g.,within visceral organs or musculatory structures); they respond to changes in the body's internal environment; detect pressure, stretch, pain, and the position of bones and joints. Stimuli refer to what input the receptor responds to. This includes temperature (thermoreceptors), chemicals (chemoreceptors), pain (nociceptors), or mechanical deformation (mechanoreceptors). Structure refers to the physical characteristics of the receptors. This includes the presence of myelin, whether their dendrites are associated with other tissues, and whether they directly synapse on other neurons. The different sensory receptors are:Free nerve endings - found in the skin; detect temperature, touch, pressure, stretch and cell damage; both tonic and phasic typesMerkel cells - tactile discs; detect light touch on the skin surface; tonicMeissner corpuscles - encapsulated nerve endings in the skin; sensitive to light touch and vibrations between 10 and 50 Hz; phasicRuffini corpuscles - found in the skin; sensitive to skin stretch and sustained pressure; show little adaptationKrause's corpuscles - found in the skin and mucous membranes; detect pressure and cold temperatures; phasicPacinian corpuscles - found in hairless skin; respond to deep pressure and vibration; phasic
Differentiate the following conditions: hyperopia and myopia. Watch the Biodigitals below to assist you in addressing this question.
Hyperopia (farsightedness) is a condition whereby the incoming light focuses in front of (ahead of the retina) thereby resulting in difficulty seeing nearby objects. Hyperopia is caused by a shortened length of the eyeball when measured from front to back (axial length) or abnormal curvature of the cornea or lens. Normally light is refracted through the layers of the eye to produce a focused image on the retina. In hyperopia, a refractive error occurs if the curvature of the eye is too flat or the eye itself is too short, producing a blurry image behind the retina, instead of a focused image on the retina. Common symptoms of hyperopia include blurry vision, headaches, strained or tired eyes, squinting, and in some cases, crossed eyes. Although both near and far objects may appear blurry, far objects are often more clearly in focus than near objects. Family history increases a patient's likelihood of developing hyperopia, and aging may also contribute to changing eye or lens shape. Although hyperopia is often present from birth, it is treatable through prescription glasses or contacts and sometimes surgery. Myopia (nearsightedness) is a condition whereby the incoming light focuses beyond the retina thereby resulting in difficulty seeing far away objects. Myopia, or nearsightedness, is a common visual condition in which the eye's ability to focus on distant objects is impaired. Most patients with myopia experience blurry vision, but the condition is treatable. Myopia is caused by a longer than normal length of the eyeball when measured from front to back (axial length) or abnormal curvature of the cornea or lens. Normally light is refracted through the layers of the eye to produce a focused image on the retina. In myopia, a refractive error occurs if the curvature of the eye is too great or the eye itself is too long, producing a blurry image in front of the retina, instead of a focused image on the retina. Common symptoms of hyperopia include blurry vision, headaches, strained or tired eyes, and squinting. Objects may be especially difficult to see when driving, especially at night. Family history increases a patient's likelihood of developing hyperopia, as does occupation, hobbies, and environmental factors. Individuals who read frequently or habitually work on a computer may be more likely to develop myopia. Time spent doing intricate, close-up work may increase risk of myopia, and some studies suggest frequent time spent outside reduces risk of myopia. Myopia is treatable through prescription glasses or contacts and sometimes surgery.
When light enters the eye it is translated to electrical impulses that must be sent to the brain for processing. Where do these electrical impulses go once they leave the eye? Follow the Biodigital below to help you answer this question.
Light in the form of action potentials leaves the retina via the optic nerve. From the optic nerve, the action potential will travel through the following structures/ optic chiasm-Once sensory stimuli reaches the retina, this information is passed out of the eye via the optic nerve. optic chiasm- After traveling through the optic nerve, some visual signals cross sides at the optic chiasm. optic tract- The signals then travel through the optic tracts and synapse in the lateral geniculate nucleus in the thalamus. lateral geniculate nucleus (of the thalamus)- The signals then travel through the optic tracts and synapse in the lateral geniculate nucleus in the thalamus. From the thalamus, visual signals travel through the white matter and out to the visual cortex in the occipital lobe of the brain. optic radiation-The optic radiation is a network of nerve fibers that transports visual information from the retina to the occipital cortex occipital cortex-the region of the brain responsible for visual processing. muscles-six extraocular muscles attach to the eyeball and control the movements of the eye. The extraocular muscles are supplied by cranial nerves and help position the eyes to enhance visual acuity.
After watching the video below, describe the different disruptions that can occur in the visual pathway (starting with a disruption to the optic nerve) and the conditions they each cause.
Light is focused onto the retina in the eyes, where the visual pathway begins (there is temporal and nasal retina). The light is subsequently transformed into electrical signals, which are transmitted to the brain via the optic nerve and then optic chiasm. It passed through optic tract, superior colliculi, lateral geniciulate nuclei and thalamus. The impulses are next processed by the occipital brain, which is in charge of visual interpretation. The impulses are subsequently transmitted along the optic radiation to other areas of the brain, where they are utilised to generate a conscious perception of the visual data in the occipital lobe which stores the primary visual cortex. Disruptions to the visual pathway due to trauma, tumors, and vascular lesions. Examples of conditions that should be discussed include tunnel vision (caused by pituitary tumors impacting the optic chiasm), anopia-blindness in one eye due to blockage in optic nerve, and various forms of hemianopia-half of the visual field for one eye affected (tunnel vision).
Review the basic anatomical structures of the ear using the Biodigital that follows. What is the function(s) of each structure that is labeled?
Located within the temporal bone of the skull and on each side of the face, the ear is a complex organ responsible for hearing and balance. External, middle, and inner ear structures conduct sound waves through the ear and to the brain via nerves. The external ear is made up of the auricle (the cartilaginous outer structure) and the external acoustic meatus (canal). The canal is lined with tiny hair follicles (cilia) and ear wax to keep foreign particles out of the ear. Sound travels through the canal to the tympanic membrane (eardrum), the outermost portion of the middle ear. Small ossicles (bones) called the malleus, incus, and stapes make up the inner portion of the middle ear. The ossicles transmit sound vibrations from the eardrum to the inner ear. The inner ear is made up of a spiral structure that responds to sound waves called the cochlea and three curved semicircular canals. The cochlea translates sound vibrations received from the middle ear into auditory signals, which are transmitted to the brain via the vestibulocochlear nerve. In addition to hearing, the inner ear is also responsible for balance.
Where does light go once it leaves the eye?
Optic nerve: vision is transformed into electrical signals or action potentials that leave the retina by means of the optic nerve; the optic nerve contains bundles of sensory axons that transmit electrical signals that travel to the optic chiasm Optic Chiasm: one may consider this a crossroads in the visual pathway as it is the structure allowing for fibers coming from the middle region of each retina to cross over to the other side; this allows each eye to share its visual field with the other eye Optic tracts: fibers leaving the optic chiasm transmit electrical signals to the thalamus via optic tracts; the thalamus allows visual information to reach the occipital lobe by means of the optic radiation The eye is a hollow sphere composed of fluid, humor, that compartmentalizes the tunics and their respective structures. Aqueous humor: located in the chamber posterior to the cornea and anterior to the lens Vitreous humor: located in the chamber posterior to the lens and anterior to the retinaThese fluids must be adequately drained. If humor accumulates it will put pressure on the retina that could impair vision - this condition is known as glaucoma
Inner-Nervous Layer:
Retina: sensory tunic of the eye that is composed of two layers:Outer pigmented layer: composed of pigmented cells that, like the choroid, absorb light preventing it from scattering as it enters the eye; these cells also act like phagocytes, removing dead and damaged receptor cells and storing vitamin A (needed for proper vision)Inner Transparent layer: neural layer, consisting of cells specialized for visual processing, the rods and cones Distribution of rods and cones in the retina:Rods and cones are not evenly distributed in the retina; they are positioned to optimize the form of vision that they are specialized in processing and sending to the cerebral cortex Rods are most densely situated at the retina's periphery and decrease in number towards the center; they are most heavily involved in peripheral and night vision as they are specialized for processing gray tones in dim light Cones are most densely situated in the center of the retina and decrease in number towards the periphery; there are 3 types of cones, each sensitive to a particular wavelength of visible light facilitating vision in color Optic disc: known as the blind spot, electrical signals leave the eye from this location in the retina en route to the cerebral cortex via the optic nerve Fovea centralis: lateral to the optic disc, the fovea centralis is the region of the retina with the greatest concentration of cones and thereby the area of greatest visual acuity
Organization
The collection of internal and external information can occur either by general or specialized sensory cells. Cells in each of these categories are capable of detecting stimuli of different forms and converting it into action potentials that travel to the CNS for interpretation. General and specialized senses differ in the structure of sensory cells, the types of stimuli that they detect, the presence of additional cooperating cells, and where in the CNS the information is sent. General sensory receptors are either somatic or visceral:Somatic - touch, pressure, temperature, proprioception, and nociceptionVisceral - information from internal organs (mostly pressure & pain)
Somatosensory Pathways
The correct detection of any general sensation depends upon the correct pathway for the transmission of information to the CNS. Mechanical deformation (pressure and touch) and body position (proprioception) information are sent via the dorsal column pathway to the somatosensory cortex. Information about pain and temperature is sent via the anterolateral pathway to other regions of the CNS. Information about pain and mechanical stress enters the spinal cord, passes through the thalamus, and is routed to specific regions of the CNS. A large part of our experience of the world is mediated through the general sensory cells that detect the effects of touch, pressure, gravity, acceleration, pain, and heat. This is critical information our body collects to alert it of danger and the presence of damage. 12.8 In-Chapter Feedback
structure of the Eye:
The eye is a hollow, fluid-filled sphere composed of three tunics - the outer fibrous tunic, the middle vascular tunic, and the inner nervous tunic.
Locate the lateral spinothalamic tract in the following illustration.
The lower half of the body, such as the trunk and the lower limbs, form the lateral spinothalamic tract.
What did you learn from the videos? List 3 points learned about the auditory system.
The video covered what sound is. How frequency of waves of sound affects the pitch of sound, and level of air pressure related to how loud sound is. The outer part of ear catches these waves and has a special designed curve which indicates direction of sound and emphasize frequencies used in human speech. The sound waves travel through ear canal and strike the ear drum. The middle ear transfers the energy, and the little bones of body control the motion of the bones. The motion then creates waves in the fluid of inner ear. The sound wave then travels through the round shaped canal which has fibers that alert us that we heard something through the nerve which then goes to the brain.
Watch the video on the dissection of the cow eye below. As you do so, take notes on the anatomy of each structure identified in the video.
cornea-anterior structure. A lot of fat, and connective tissue around it protect from a blow to head which can cause delicate structures of eye to be damaged. optic nerve-tube like nerve going straight to the brain. eye muscle-allow eye to move sclera-under all connective tissue. Very tuff material to cut through. Liquid inside eyes helps maintain shape of cornea and eye. aqueous and vitreous humors-liquid inside eye which helps maintain shape of eye. Jelly like substance-vitreous humors which help maintain shape of the eye and press retina against the inside of the eye. retina-cream colored material covers inside of the eye. Holds all the photo receptors which detect incoming light. Retina pass through axons of the nerve in the retina which pass through back of the eye aka optic disc. optic disc-light cannot be detected there. All axons make optic nerve. choroid-very vascular that serves the eye. black color absorbs light. lens-anterior part of the eye. Gum ball shape. function is focusing the light in proper place. Very clear color and soft. iris, pupil-smooth looking structure-iris responsible for allowing more or less light entering eye. Pupil-hole which becomes larger or smaller by iris direction.
The consists of rods and cones where light processing begin
inner transparent layer
