Learning Outcomes Exam 6 PDF

Exam 6 Learning Outcomes Chapters 15-16 What you need to know for the “new” part (85%) of Exam 6. Cumulative questions will make up about 15%. Note: Information from any in-class activities such as case studies is also fair game f...

Exam 6 Learning Outcomes Chapters 15-16 What you need to know for the “new” part (85%) of Exam 6. Cumulative questions will make up about 15%. Note: Information from any in-class activities such as case studies is also fair game for exams. Ch. 15: Autonomic Nervous System Section 15.1 General Properties of the Autonomic Nervous System 1. Explain how the autonomic and somatic nervous systems differ in form and function. (see table 15.1 and fig. 15.2) a. Autonomic nervous system/visceral motor system – motor nervous system that controls glands, cardiac muscle, and smooth muscle; involuntary b. Somatic nervous system – Single-neuron chain from the central nervous system (CNS) directly to skeletal muscle; Heavily myelinated axons for rapid signal transmission; voluntary 2. Describe visceral reflex arcs, including structural and functional details of sensory and motor (autonomic) components. (see fig. 15.1) a. Unconscious, automatic, stereotyped responses to stimulation b. Includes receptors (nerve ending detect stretch, tissue damage, blood chemistry, body temp, and other internal stimuli), afferent neurons that lead to integrating center and interneurons in CNS, efferent neurons carrying motor signals away from CNS, and effector that carries out response 3. Explain how the two divisions of the autonomic nervous system (sympathetic and parasympathetic divisions) differ in general function. a. Define autonomic tone. – balance between sympathetic and parasympathetic activity b. Identify the anatomical components and nerve pathways of the sympathetic and parasympathetic divisions. i. Sympathetic division - Thoracolumbar region of the spinal cord (T1-L2); Short preganglionic neurons synapse with long postganglionic neurons in ganglia located close to the spinal cord 1. Neurotransmitters: Acetylcholine (Ach) released by preganglionic neurons, norepinephrine (NE) released by postganglionic neurons 2. Nerve pathways - Thoracolumbar outflow: Pre-ganglionic neurons exit the spinal cord and synapse in the sympathetic chain ganglia or prevertebral ganglia. 3. Postganglionic neurons: These neurons then project to target organs, such as the heart, lungs, blood vessels, and digestive tract. ii. Parasympathetic division - Craniosacral region of the CNS; Long preganglionic neurons synapse with short postganglionic neurons in ganglia located near or within the target organs.  1. Neurotransmitters: Acetylcholine (Ach) released by both preganglionic and postganglionic neurons 2. Nerve pathways - Cranial nerves innervate the head, neck, and thoracic organs; Sacral outflow: Sacral nerves innervate the pelvic organs c. Contrast the anatomy of the parasympathetic and sympathetic systems, including central nervous system outflow locations, ganglia locations, pre- and post-ganglionic neuron relative lengths, and ganglionic and effector neurotransmitters. (see fig. 15.2, 15.8) i. Somatic pathway 1. Motor neuron in brainstem or spinal cord issues myelinated fiber (axon) that reaches skeletal muscle ii. Automatic pathway 1. Signal travels across 2 neurons to get target organ, crosses synapse where 2 neurons meet in autonomic ganglion 2. Axon of 1st neuron in pathway called preganglionic fiber; axon extends from brainstem/spinal cord to autonomic ganglion outside CNS, then synapse w/ second neuron and secretes neurotransmitter Ach 3. Axon from 2nd neuron called postganglionic fiber leaves d. Discuss the relationship of the adrenal glands to the sympathetic nervous system. i. Sympathetic Nerve Stimulation: When the body perceives a threat, the sympathetic nervous system is activated. This triggers the release of acetylcholine from preganglionic neurons, which stimulates the adrenal medulla. ii. Hormone Release: The adrenal medulla, in response to this stimulation, releases two primary hormones: 1. Epinephrine (adrenaline): This hormone increases heart rate, blood pressure, and blood sugar levels, providing a surge of energy. 2. Norepinephrine (noradrenaline): This hormone works in conjunction with epinephrine to enhance the body's response to stress. iii. Amplified Response: The release of these hormones amplifies the effects of the sympathetic nervous system, further preparing the body for action. This includes increased alertness, heightened senses, and improved muscle function. Section 15.2 Anatomy of the Autonomic Nervous System 4. Identify the anatomical components and nerve pathways of the sympathetic and parasympathetic divisions a. Sympathetic i. Thoracolumbar division – begin in thoracic and lumbar region which is why its called like this ii. Synapse with post-ganglionic neurons most commonly at sympathetic chain (paravertebral) ganglia, or at adrenal medulla iii. Define splanchnic nerve – some nerves that pass through sympathetic ganglia w/o synapsing, beyond ganglia they travel to splanchnic nerves, which lead to collateral ganglia; preganglionic fibers synapse w/ postganglionic neurons b. Parasympathetic i. Craniosacral division – signaling pathways begin in brain and sacral region of spinal cord; travel in certain cranial and sacral nerves  ii. Synapse with post-ganglionic neurons most commonly at terminal ganglia near organ iii. Cranial nerves that carry parasympathetic fibers: 1. Oculomotor, facial, glossopharyngeal 2. Vagus nerve (CN X): carries 90% of all parasympathetic preganglionic fibers 5. Discuss the relationship of the adrenal glands to the sympathetic nervous system (see fig. 15.6 and section 15.2b) a. Rest like hats on superior poles of kidneys; outer rind called adrenal cortex secretes steroid hormones; inner core called adrenal medulla is a sympathetic ganglion 6. Describe the enteric nervous system of the digestive tract and explain its significance. a. Doesn’t arise from brainstem or spinal cord, it innervates smooth muscle and glands; functions independently of rest of nervous system and is influenced by vagus nerves. b. Regulates motility of esophagus, stomach, and intestines and secretion of digestive enzymes and acid; digestive activities require regulation by sympathetic and parasympathetic system Section 15.3 Autonomic Effects on Target Organs 7. Name the neurotransmitters employed at different synapses of the ANS. (see fig. 15.8) a. Sympathetic preganglionic fibers: ACh b. Sympathetic postganglionic fibers: NE c. Parasympathetic preganglionic fibers: ACh d. Parasympathetic postganglionic fibers: ACh 8. Name the receptors for these neurotransmitters and explain how they relate to autonomic effects. a. Differentiate between types of cholinergic receptors (muscarinic and nicotinic) i. Any neuron that secretes ACh is called cholinergic neuron and any receptor that binds is called cholinergic receptor; 2 types of cholinergic receptors 1. Muscarinic receptors – named for muscarine which is mushroom toxin; all cardiac muscle, smooth muscle and gland cells 2. Nicotinic receptors – nicotine; occur at synapses in autonomic ganglia, where the preganglionic fibers stimulate the postganglionic cells; always excitatory b. Differentiate between locations of cholinergic and adrenergic nerve fibers (see Table 15.4) i. Sympathetic division has preganglionic fibers that are always cholinergic, most postganglionic fibers will be adrenergic and a few cholinergic ii. Parasympathetic division has preganglionic fibers that are always cholinergic, and its postganglionic fibers will always be cholinergic c. Know the locations and effects of all adrenergic receptors. i. a-adrenergic receptor: excitatory effects; promotes labor contractions, stimulates piloerections, constricts dermal blood vessels and inhibits intestinal motility 1. a1 act thru calcium ions as second messenger 2. a2 receptors inhibit synthesis of cyclic AMP (cAMP) ii. b-adrenergic receptors: usually inhibitory, but can also have excitatory effects 1. b1 and b2 both act through cAMP as second messenger  d. Know which enzymes break down acetylcholine (AChE: acetylcholinesterase) and epinephrine/norepinephrine (COMT and MAO: Monoamine oxidase). 9. Explain how the ANS controls many target organs through dual innervation. a. Target organs to know: heart, blood vessels (of viscera), bronchioles, pupil diameter, sweat glands i. 1. Heart: 1. Sympathetic: Increases heart rate and force of contraction (fight-or- flight response). 2. Parasympathetic: Decreases heart rate and force of contraction (rest- and-digest response). ii. 2. Blood Vessels (of Viscera): 1. Sympathetic: Constricts blood vessels, reducing blood flow to the viscera. 2. Parasympathetic: Dilates blood vessels in some areas, increasing blood flow to the viscera. iii. 3. Bronchioles: 1. Sympathetic: Dilates bronchioles, allowing for increased airflow (important for exercise or stress). 2. Parasympathetic: Constricts bronchioles, reducing airflow (important for rest). iv. 4. Pupil Diameter: 1. Sympathetic: Dilates the pupil (mydriasis), allowing for more light entry (useful in dim light or during alertness). 2. Parasympathetic: Constricts the pupil (miosis), reducing light entry (useful in bright light or during rest). v. 5. Sweat Glands: 1. Sympathetic: Stimulates sweat production, aiding in thermoregulation (cooling the body during exercise or stress). 2. Parasympathetic: Minimal or no effect on sweat glands. 10. Define dual innervation (section 15.3b, see fig. 15.9) a. When viscera receive nerve fibers from both sympathetic and parasympathetic divisions 11. Explain how control is exerted in the absence of dual innervation (section 15.3c, see fig. 15.10) a. ANS can exert precise control over target organs through tonic activity and modulation of neurotransmitter release. This allows for a wide range of physiological responses, ensuring that the body can adapt to various internal and external conditions Adrenergic Major Locations Effect Receptor β1 Heart, kidneys, adipose tissue Increase heart rate and force of contraction, stimulates kidneys to secrete renin (involved in blood pressure regulation) Β2 Lungs, blood vessels serving heart, liver, Mostly inhibitory, dilates blood vessels and skeletal muscle bronchioles, relaxes smooth muscle β3 Adipose tissue Stimulates lipolysis α1 Blood vessels of skin, mucosae, abdominal Constricts blood vessels and visceral organ viscera, kidneys, salivary glands, sympathetic sphincters, dilates pupils organs except heart α2 Membrane of adrenergic axon terminals, Inhibits NE release from adrenergic axon pancreas, blood platelets terminals, inhibits insulin secretion by pancreas, promotes blood clotting Agonist stimulates receptors; Antagonist blocks the receptor Section 15.4 Central Control of Autonomic Function a. Identify what parts of the brain influence the autonomic nervous system. a. Cerebral cortex – anger, fear, thoughts of good food, sexual thoughts or stimulation increase blood flow to genitals, and anxiety inhibits sexual function; emotional responses? b. Hypothalamus – major control center of ANS/visceral motor system; hunger, thirst, thermoregulation, emotions and sexuality c. Midbrain, pons, and medulla oblongata – cardiac and vasomotor control, salivation, swallowing, sweating, gastrointestinal secretion, bladder control, pupillary constriction and dilation, primitive functions d. Spinal cord – autonomic reflexes as micronutrition (urination), defecation, erection and ejaculation Ch. 16: Special Senses Section 16.1 Properties and Types of Sensory Receptors 1. Define receptor and sense organ. a. Receptor – structure specialized to detect stimulus b. Sense organ – structure that combines nervous tissue w/ other tissues that enhance response to certain stimuli 2. Define transduction. a. Conversion of one form of energy to another into nerve signals 3. List the four kinds of information obtained from sensory receptors and describe how the nervous system encodes each type. a. Modality – type of stimulus or perception it produces; ex vision hearing and taste; determined by where sensory signals end in brain b. Location – also define receptive field and two-point discrimination (see fig 16.1) i. Encoded by neurons issuing signals to brain ii. Receptive field – sensory neuron detects stimuli within an area iii. Fingertips have finer two-point touch discrimination than skin on back c. Intensity – whether sound is loud or soft, light is bright or dim, pain is mild or excruciating, etc. d. Duration – how long stimulus lasts  i. Define adaptation – is stimulus prolonged, firing of neuron gets slower over time and becomes less aware of stimulus ii. Distinguish between phasic receptors and tonic receptors 1. Phasic receptors – generate burst of action potentials when first stimulated, then adapt and reduce or stop signaling even if stimulus continues; found in smell, hair movement and cutaneous pressure and vibration 2. Tonic receptors – adapt slowly and generate signals more steadily; proprioceptors and pain receptors are among most persistently responding tonic receptors because brain always aware of body position, muscle tension, joint motion or pain e. Explain the phenomenon of adaptation. 4. Outline three ways of classifying receptors: a. Stimulus modality: thermoreceptors, photoreceptors, nociceptors, chemoreceptors, mechanoreceptors i. Thermoreceptors – heat and cold; skin ii. Photoreceptors – eyes respond to light iii. Nociceptors – pain iv. Chemoreceptors – chemicals, odors, tastes, and body fluids membranes v. Mechanoreceptors – physical deformation of cell or tissue caused by vibration, touch, pressure, stretch, or tension b. Origin of stimulus: exteroceptors, interceptors, proprioceptors i. Exteroceptors – sense stimuli external to body ii. Interceptors – detect stimuli internal organs iii. Proprioceptors – sense position and movements of body and body parts c. Distribution in the body: general vs. special senses i. General – distribute to skin, muscles, tendons, joints, and viscera ii. Special – limited to head, innervated by cranial nerves, and employs relatively organs Section 16.2 The General Senses 5. List the types of somatosensory receptors (see Table 16.1). 6. a. Describe each of the following types of receptors, indicating what sensation it detects and giving an example of where it can be found in the body: i. pain receptors (nociceptors) – tissue/potential damage; found throughout body (skin, muscles, internally) ii. temperature receptors – change in temp; found on skin and internally iii. mechanoreceptors – mechanical deformation of receptor; proprioception 1. proprioceptors – detects change in muscle length and joint angle, found in muscle, tendons, and joints 2. baroreceptors/pressoreceptors – detects change in blood pressure, found in walls of blood vessels iv. chemoreceptors – chemical substances; found in nose, tongue, and carotid and aortic bodies; smell, taste, blood gas levels v. photoreceptors – light; found in retina of eye (rods and cones); vision 7. Refresh your memory on somatosensory projection pathways (see section 16.2c, also originally part of the information on spinal tracts from Ch 13) a. Complex system of neurons that transmits sensory information from body to brain; data includes sensations such as touch, pressure, pain, temperature, and proprioception b. Sensory projection is transmission of data from receptor to specific locality in cerebral cortex which enables brain to detect and identify stimulus c. Signals travel by 3 neurons called 1st, 2nd, and 3rd neurons, axons called fibers i. 1st fibers for touch pressure, proprioception is large, myelinated and fast, heat and cold are small, unmyelinated or lightly, and slow ii. In brainstem, 1st order fiber synapse w/ 2nd that decussate and lead to thalamus, 3rd order neuron complete pathway to cerebellum; proprioceptive signals from head are exception as second order fibers carry them to cerebellum d. First order fibers enter posterior horn of spinal cord; signals ascend cord in spinothalamic; signals for proprioception below head travel up spinocerebellar tracts to cerebellum; signals from thoracic and abdominal viscera travel to medulla oblongata by way of sensory fibers in vagus nerve CN X; visceral pain signals ascend spinal cord in gracile fasciculus 8. Describe the types and mechanisms of pain. a. Define pain – unpleasant perception of actual or potential tissue damage; symptom of underlying condition b. Define visceral pain, deep somatic pain, neuropathic pain, referred pain i. visceral pain – internal organs; diffuse, dull and difficult to locate; associated w/ feelings of squeezing, cramping, and nausea ii. deep somatic pain – bones, joints, muscles; arthritis, sprains, bone fractures; results from excessive stretch sprain/pulled muscle) iii. neuropathic pain – injuries to nerves, spinal cord, meninges, or brain iv. referred pain – pain from one part of the body is perceived as coming from another part c. Know the projection pathways for pain (fig 16.3) i. First order nerve fiber conducts pain signal to posterior horn of spinal cord; second order fiber conducts to thalamus, third order fiber conducts to cerebral cortex ii. Signals from spinothalamic tract pass through thalamus; signals from spin reticular tract bypass thalamus otw to sensory cortex d. Define analgesic, endorphins, opioids i. Analgesic – substance that relieves pain ii. Endorphins - Natural chemicals produced by the body that act as pain relievers and mood elevators. They bind to the same receptors in the brain as opioids iii. Opioids - A class of drugs that mimic the effects of endorphins, providing pain relief and altering mood. Opioids can be natural (like morphine), semi-synthetic (like oxycodone), or synthetic (like fentanyl). They are highly addictive and can lead to serious health problems if misused. e. Know how spinal gating works (fig. 16.5). Note that the first steps from the first-order neuron from the nociceptor through the third-order neuron that lands in the cerebral cortex is the same pathway as the spinothalamic tract. i. Pain signals can be stopped at dorsal horn 1. - 2. Section 16.3 – Omit Section 16.4 Hearing and Equilibrium 9. Identify the properties of sound waves that account for pitch and loudness. a. Pitch is high/treble or low/bass; determined by frequency at which sound source, eardrum, and other parts of ear vibrate i. Cycle – movement of vibrating object back and forth ii. Frequency - # of cycles per second b. Loudness is perception of sound energy, intensity or amplitude of vibration i. Amplitude is measure of how far forward back the cone vibrates on each cycle and how much it compresses 10. Describe the gross and microscopic anatomy of the ear (see fig. 16.11 and 16.13) a. Identify the hearing structures of the outer, middle and inner ear. i. Outer ear: auricle – outside part of ear, auditory canal (external acoustic meatus) – passage leading temporal bone to eardrum ii. Middle ear: tympanic membrane (eardrum), ossicles (malleus, incus, stapes) – bones that connect the tympanic membrane to inner ear, oval window – ringlike ligament where inner ear begins, round window – covered by membrane called secondary tympanic membrane iii. Inner ear: cochlea – organ of hearing, scala vestibuli – superior fluid filled chamber, cochlear duct – middle triangular space chamber (scala media), scala tympani – inferior fluid filled chamber 1. Bony labyrinth: vestibule, semicircular canals 2. Membranous labyrinth: utricle, saccule, semicircular ducts, ampulla(e) iv. Receptors: spiral organ, macula, crista ampullaris 1. Spiral organ has epithelium composed of hair cells and supporting cells 2. Macula – supporting cells 3. Crista ampullaris – within ampulla is mound of hair cells and supporting cells b. Roles of the accessory structures i. Describe the functions of the ceruminous glands. 1. Secretions mix w/ dead skin cells and form cerumen (earwax) ii. Describe the role of the auditory tube in drainage and equalization of pressure in the middle ear. 1. Auditory tube: passageway to nasopharynx; serves to aerate and drain middle ear; normally closed but swallowing and yawning opens it and allows air to enter tympanic cavity which equalizes air pressure 11. Explain how the ear converts vibrations to nerve signals and discriminates between sounds of different intensity and pitch. a. Describe how the various structures of the outer, middle and inner ear function in hearing. i. Describe how the spiral organ converts sound waves into action potentials (see fig. 16.17) 1. Spiral organ is composed of hair cells; tips of hair cells are bathed in high potassium fluid, the endolymph, by cells around circumference of cochlear duct; vestibular membrane retains fluid in duct; K+ gives endolymph electrical potential, so there’s strong electrochemical gradient from endolymph to hair cell cytoplasm which provides  potential energy that enables hair cell to work; inner hair cells which generate all signals we hear has transmembrane protein which serves as gated ion channel 2. Summary – each upward movement of basilar membrane pushes inner hair cells together to stationary tectorial membrane; stereocilium has tip link connecting ion channel at top of next shorter stereocilium; when taller one bends, it pulls channels open and potassium ions flow into hair cell and depolarize; hair cell releases burst of neurotransmitter, exciting sensory processes of cochlear nerve cells below it; signal generated in cochlear nerve and transmitted to brain 3. Loud sound vibrates longer segments of basilar membrane and thus excites a greater number of hair cells b. Describe the sound conduction pathway from the auricle (pinna) to the fluids of the inner ear and the path of nerve impulses from the spiral organ to various parts of the brain. (See fig. 16.16 for some of the first part and fig 16.19 for the last part from the cochlear nerve —> auditory cortex) i. Cochlear nerves -> vestibular nerve -> pons-> inferior colliculus -> medial geniculate nucleus of thalamus -> primary auditory ii. Transmitted thru vibrations iii. Sound waves coming into ear -> tympanic membrane -> malleus -> incus -> stapes -> oval window-> stapes vibration causes fluid in scala tympani to vibrate as it crosses over cochlear duct and basilar membrane is disturbed; vibration of receptors = depolarization 1. Cochlear + vestibular = vestibulocochlear nerve which heads towards pons and heads up to inferior colliculus and then to thalamus, then to primary auditory cortex c. Explain how the structures of the ear enable differentiation cortex of pitch and loudness of sounds. (See fig. 16.18) i. If brain detects moderate firing rates associated w/ hair cells in relatively narrow bands of cochlea, it interprets as soft sound; if detects firing frequency in nerve fibers associate w/ broader bands, it interprets this as louder sound; when brain receives signals main from inner hair cells at distal end, it interprets the sound as low pitched; when signals come mainly from proximal end, it interprets the sound as high pitched 12. Explain how the vestibular apparatus enables the brain to interpret the body's position and movements. a. Distinguish between static and dynamic equilibrium. (See section 16.4d) i. State equilibrium, perception of the orientation of head in space dynamic equilibrium, the perception of motion or acceleration b. Describe the structure of the maculae and their function in static equilibrium. (See fig. 16.20) i. Include: otoliths, otolithic membrane, hair cell, supporting cell, vestibular nerve. 1. Otolithic membrane is weighted w/ protein calcium carbonate granules called otoliths which adds the inertia of the membrane and enhances sense of gravity and motion 2. w/ head erect, otolithic membrane bears directly down hair cells, stimulation is minila; when head tilts, heavy otolithic membrane sags and bends stereocilia, stimulating hair cells  ii. Understand that gravity acts on the otolithic membrane when you move your head or accelerate, and the movement of the otolithic membrane causes the hair cells to bend, which causes depolarization of hair cells. iii. Head position is determined in your brain by how the otolithic membrane sags/bends hair cells in your right and left macula sacculi and right and left macula utriculi. As your head changes positions, the rate of action potentials changes in each receptor. c. Describe the structure of the crista ampullaris and its function in dynamic equilibrium. i. Include: semicircular ducts, cupula, endolymph, hair cells, vestibular nerve fibers. 1. Ducts are filled w/ endolymph, each opens utricle and has dilated sac at one end called ampulla; within ampulla is mound of supporting cells called crista ampulla; hair cells have stereocilia and kinocilium embedded in capula, a gelatinous cap that extends from crista to roof of ampulla; when head turns, duct rotates but endolymph lags behind, pushed cupula, bends stereocilia and stimulates hair cells d. Describe how the vestibular apparatus enables the brain to interpret the body’s position and movements (vestibular projection pathways, see fig. 16.22) i. Fibers of vestibular apparatus lead to complex of four vestibular nuclei on each side of pons and medulla; nuclei on right and left sides of brainstem communicate extensively w/ each other, so each receives input from both right and left ears; they process signals about position and movement of body and relay data to 5 targets (cerebellum, reticular formation, spinal cord, thalamus, and nuclei of oculomotor, trochlear, and abducens nerve (CN’s III, IV, VI)) 13. Disorders to know (look up if not in the text) a. Otitis media (see deeper insight 16.1 pg. 580) i. Middle ear inflammation ii. Common result of sore throat iii. Frequent case of hearing loss in children iv. Eardrum bulges and becomes inflamed v. Usually treated with antibiotics vi. Accumulation of large amounts of fluid/pus: myringotomy (lance the eardrum) & implant a tube to drain b. Conduction deafness - something hampers sound conduction to the fluids of internal ear (Ex. Compacted earwax, ruptured eardrum) c. Sensorineural deafness - damage to any neural structures between cochlear hair cells – auditory cortical cells Section 16.5 Vision 14. Describe the anatomy of the eye and its accessory structures. a. Know the 6 extrinsic eye muscles, what actions they perform, and which cranial nerve innervates them. (see fig 16.25) Extrinsic Eye Muscle Action Cranial Nerve Lateral Rectus Moves eye Laterally Abducens (VI) Medial Rectus Moves eye Medially Oculomotor (III) Superior Rectus Elevates eye and turns it medially Oculomotor (III) Inferior Rectus Depresses eye and turns it medially Oculomotor (III) Inferior Oblique Elevates eye and turns it laterally Oculomotor (III) Superior Oblique Depresses eye and turns it laterally Trochlear (IV) b. Know the function of the fovea centralis and macula lutea i. Macula lutea 1. Oval “yellow spot” in exact posterior 2. Lateral to optic disc 3. Fovea centralis – tiny pit in center a. Contains only cones b. Images focused when placed directly on fovea c. Why is the optic disc called the blind spot? (Pg. 596) i. It’s a weak spot, has no sclera, and there are no photoreceptors (brain “fills in”) 15. Discuss the structure of the retina and its receptor cells. a. Retina is inner layer which originates from the brain, has millions of photoreceptors which transduce light energy i. Has 2 layers; outer pigmented layer which absorbs light and inner neural layer that deals w/ vision ii. Thin transparent membrane attached to rest of eye w/ 2 points: optic disc where optic nerves leave rear of eye and ora serrata which is scalloped anterior margin 16. Explain how the optical system of the eye creates an image on the retina. a. Trace the path of light as it passes through the eye to the retina and the path of nerve impulses from the retina to various parts of the brain. i. Understand that the light refracts (bends) light when it comes into the eye at the cornea and the lens b. Define emmetropia – state which eye is relaxed and focused on object more than 6m (20ft) away; light rays coming from object are parallel and rays are focused on retina w/o effort c. Describe the near response – adjustment to close range vision involves 3 processes to focus image on retina (convergence of the eyes, constriction of the pupil, accommodation of the lens) (see fig. 16.33) i. Convergence of eyes – moving finger closer to baby’s nose will make it look cross eyed; convergence of eyes orients visual axis of eyes toward object to focus its image on each fovea ii. Constriction of pupil - also known as miosis, is the narrowing of the pupil, the black circle in the center of your eye. This is a normal physiological response to bright light or near vision. The iris, the colored part of the eye, contracts to reduce the size of the pupil, limiting the amount of light entering the eye and protecting the retina from damage iii. Accommodation of lens – accommodation is change in curvature of lens that enables us to focus on nearby objects d. Describe hyperopia and myopia and what type of lenses correct for these. (see fig. 16.35) i. Hyperopia – farsightedness; eyeball too short; corrected w/ convex lenses  ii. Myopia – nearsightedness; eyeball too long; corrected w/ concave lenses 17. Discuss how the retina converts this image to nerve signals (phototransduction) – how we take light and convert them into action potentials a. Describe how light activates photoreceptors. (receive light) (see fig 16.39) i. Visual pigments: rhodopsin (opsin and retinal) 1. Inside rods a. Have 2 parts; retinal and opsin i. Retinal changes shape when light is absorbed; when retinal absorbs light it becomes transretinal ii. Opsin is protein part ii. Rhodopsin bleaching (see fig. 16.39) 1. Hyperpolarization and action potential propagate along optic nerve 2. When light is being absorbed b. Explain the mechanism of generating visual signals (fig. 16.40) i. Darkness: 1. Rods are depolarized because sodium ion channel is open. The rod releases glutamate onto bipolar cells. 2. Bipolar cells are hyperpolarized (glutamate inhibits them) 3. Ganglion cells receive no stimulus from bipolar cells, and therefore do not send any action potentials along the optic nerve. ii. Light: 1. Rods are hyperpolarized because sodium ion channel closes. 2. Bipolar cells are depolarized because there is a lack of glutamate/inhibition from the rods. Bipolar cells release neurotransmitter that binds to receptors on ganglion cells. 3. Ganglion cells are depolarized (from bipolar cell neurotransmitter binding to receptors on ganglion cell), and ganglion cells send action potentials along optic nerve. iii. Rods and bipolar cells can depolarize/hyperpolarize but cannot send action potentials. Only ganglion cells can send action potentials. c. Compare and contrast the function of rods and cones in vision. i. Rods – dim light, peripheral vision, black/white ii. Cones – bright light, high-res color 18. Explain the process of light and dark adaptation. (Pg. 602-603) a. During light, ion channel closes and no sodium allowed in, during dark sodium is allowed in and causes depolarization b. Light adaptation occurs when you go from dark/dimly lit area into brighter light i. Rod pigments bleached by lights in room c. Eyes undergo dark adaptation before you can see well enough to find way through dark i. Takes a while for rods to adjust to dark 19. Describe the mechanism of color vision (generally) a. Well developed in primates for evolutionary reasons; based on three kinds of cones named for absorption peaks of their photopsins: short wavelength cones, medium wavelength cones and long wavelength cones; blue green and red cones b. Cones in photoreceptor cells responsible for color vision; in brain, signals are processed and interpreted to create perception of color 20. Trace the visual projection pathways in the brain. (see fig. 16.45)  a. visual pathway is a complex neural network that carries visual information from the retina to the visual cortex in the brain b. c. Diagram of hemi decussation and projection to primary visual cortex. Blue and yellow are visual fields of left and right eyes; green is area of overlap and stereoscopic vision. Nerve fibers from medial side of right eye (red) decussate to left side of brain, while fibers from lateral side remain on right side of brain. Converse is true of left eye. Right occipital love monitors left side of visual field and left occipital lobe monitors right side 21. Eye diseases and disorders to know: a. Myopia (see table 16.2) – nearsightedness; eye too long; need concave lenses b. Hyperopia (see table 16.2) – farsightedness; eye too short; need convex lenses c. Diplopia (see section 16.5d) – double vision; when extrinsic muscles are not perfectly coordinated, can’t focus properly; seeing two images instead of one d. Cataracts (see deeper insight 16.3) – clouding of lens; world appears distorted/frosted glass; lens transparent; age related or due to smoking, diabetes, excessive sun e. Macular degeneration (see deeper insight 16.3) – age related disease; degenerative disorder of retina; peripheral vision intact, central vision blurred, no treatment f. Strabismus – double vision due to the inability to fixate on the same point with both eyes Cumulative material to consider reviewing: The somatic nervous system (the neurons that participate in the neuromuscular junction) o Understand the process of neurotransmitter release (acetylcholine), binding to receptors on the muscle fiber, and the subsequent muscle contraction. Somatic reflex arcs o Review the basic components: sensory receptor, sensory neuron, integration center (spinal cord or brainstem), motor neuron, and effector (muscle). Practice identifying different types of reflexes (e.g., stretch reflex, withdrawal reflex). Cranial nerves that participate in the autonomic nervous system, vision, and hearing/equilibrium  o Autonomic Nervous System: Focus on cranial nerves III (oculomotor), VII (facial), IX (glossopharyngeal), and X (vagus). Understand their roles in parasympathetic and sympathetic functions. o Vision: Understand the role of cranial nerves II (optic), III, IV (trochlear), and VI (abducens) in eye movements and visual perception. o Hearing/Equilibrium: Focus on cranial nerve VIII (vestibulocochlear) and its role in auditory and vestibular functions. Cerebral white matter tracts in the brain, especially projection tracts o Projection Tracts: Review the major projection tracts, such as the corticospinal tract, spinothalamic tract, and medial lemniscus. Understand their functions in motor control, sensory perception, and other processes. Spinal sensory tracts involved in pain o Spinothalamic Tract: Understand the different types of pain fibers (A-delta and C fibers) and their role in fast and slow pain perception. G protein-coupled/second messenger receptor systems o General Mechanism: Review the basic steps: ligand binding, receptor activation, G protein activation, second messenger production, and cellular response. o Specific Examples: Understand the role of G protein-coupled receptors in neurotransmitter signaling, hormone signaling, and sensory perception. Quiz 15 Place the following components of an autonomic reflex arc into the correct order. 1 - sensory receptor 4- motor neuron 3 - integration center 5 - effector 2 - sensory neuron Correctly match the following effects of the sympathetic or parasympathetic systems. 1 - increase in lipid breakdown 1 - Short pre-ganglionic neurons and long post-ganglionic neurons 1 - Also called the thoracolumbar division, because neurons emanate from those areas of the spinal cord. 1 - pupil dilation 2 - increase in urination 2 - Also called the craniosacral division, because neurons emanate from those areas of the spinal cord. 1 - bronchiole dilation 1 - increase in heart rate 2 - increase in digestion 2 - Long pre-ganglionic neurons and short post-ganglionic neurons 1. Sympathetic 2. Parasympathetic Match the neurons with the correct neurotransmitter they secrete. 1 - parasympathetic preganglionic neurons 1 - somatic motor neurons 1 - parasympathetic postganglionic neurons 2 - sympathetic postganglionic neurons 1 - sympathetic preganglionic neurons 1.acetylcholine 2.norepinephrine How do sympathetic preganglionic neurons connect with their postganglionic neurons? (Select all that apply.) They may synapse at the prevertebral ganglia They may synapse at the adrenal medulla They may synapse at the sympathetic trunk ganglion Where can you find beta 2 receptors? Blood vessels Skeletal muscle Lungs Epinephrine and norepinephrine are both synthesized from which amino acid? histidine tryptophan dopamine tyrosine glutamate Sympathetic nervous system output can affect which of the following? (Select all that apply.) renin release thermoregulation blood glucose levels Which of the following is true of the sympathetic and parasympathetic divisions concerning dual innervation? Select all that apply. Most body organs will have innervation from both divisions Sympathetic and parasympathetic effects always occur simultaneously. All tissues will have equal innervation from both divisions. Sympathetic and parasympathetic effects are often antagonistic but can also be cooperative in some tissues. Binding of acetylcholine to a nicotinic receptor results in an _______ effect. permissive excitatory inhibitory antagonistic synergistic This adrenergic receptor can be found in multiple organs and blood vessels, and causes constriction of blood vessels. alpha-1 alpha-2 beta-1 beta-2 beta-3 quiz 16 special senses What is transduction? Awareness of stimuli Converting sensory stimuli into nerve signals Converting ATP into energy The type of stimuli detected. The type of stimuli detected. Correctly match the receptor to the stimulus it transduces. linear acceleration - maculae rotational acceleration - crista ampullaris hearing- spiral organ Which receptor detects pain stimulus? nociceptors mechanoreceptors chemoreceptors thermoceptors baroreceptors Most pain sensation is sent along this tract: dorsal column medial lemniscal tectospinal corticospinal spinoreticular spinothalamic A change in the curvature of the lens in order to focus on a nearby object is called myopia accommodation hyperopia emmetropia convergence In the hyperopic eye, the eyeball is too ______, but vision can be corrected with _____ lenses. Short, concave Short, convex Long, concave Long , convex What is the main function of the rods in the eye? Color vision Vision in dim light Accommodation for blind spot Accommodation for near vision Depth perception What happens when rods are "bleached"? Action potentials are sent by photoreceptors Retinal changes shape Opsin changes shape Glutamate is released Which of the following is true of rods in darkness? (Select all that apply.) The sodium/calcium ion channel is open The sodium/calcium ion channel is closed Retinal activates a G protein-linked receptor Light passes over the following cells in which order? bipolar cells - 2 photoreceptor - 3 ganglion cells - 1 How do the maculae respond to changes in gravity? Changing the rate of action potentials Changing how far the cupula “tips over” Changing the intensity of action potentials Changing the number of otoliths on the membrane When you spin in a chair with your eyes closed, in what location do receptors sense this movement? ampullae spiral organ cochlea vestibule saccule and utricle Which receptor is responsible for transmitting gravitational equilibrium information that monitors the position of the head? cristae ampullaris maculae lamellar corpuscles spiral organ photoreceptors How are the hair cells on the maculae stimulated? Wavelengths of light are absorbed, which causes a conformational change. Vestibular waves disturb the receptor The otolithic membrane sags down as gravity changes. The endolymph in the semicircular ducts rotates and disturbs the cupula. Sound waves disturb the receptor. The stapes transmits sound waves through the oval window, then through what structure do the sound waves travel next? cochlear duct perilymph endolymph spiral organ basilar membrane How is frequency of sound (pitch) determined by the brain? (Select all that apply.) Where the sound waves pass through the basilar membrane in the cochlea How many of the auditory ossicles vibrate Whether the sound waves stimulate the maculae or the crista ampularis Identify the correct pathway for auditory information. cochlear nerve - 1 vestibulocochlear nerve - 2 primary auditory cortex – 5 inferior colliculus – 3 medial geniculate nucleus of the thalamus - 4