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ANSC exam II
peripheral nervous system vs central nervous system - Answer -the part of the nervous system that lies outside of the CNS (nerves and ganglia). = connections "hooked' to CPU -the nerve body of the first nerves of the PNS are located in the CNS and their axons extend out of the CNS into the body. -some of these connections take information to the CNS (what we will refer to as sensor information) and some will take information from the CNS to the body to cause action (what we will refer to as motor function) CNS= brain and spinal cord = processing (CPU), They take information in from the peripheral nervous system, interpret it and, in most cases, trigger a response. ex. If oxygen is low in a certain area (say in the limbs because the animal has been running), the CNS will take that information send out signals to the PNS causing shifts in blood flow pattern to raise oxygen in the affected area. -special senses-->CNS-->motor function innervate - Answer -to turn on Parts of a nerve - Answer -dendritic region- Top region of a nerve cell where electrical charges originate cell body- nucleus, organelles, cytoplasm axon-long extension located below the nerve cell body which general transport electrical impulses away from the cell body
synapse- very ends of neurons explain process of nerve impulse - Answer -impulse - a directional electrical impulse that normally migrates from the dendritic region to the end of the axon -at resting potential (-70) -depolarization: Stimulation causes channels to open in the membrane at the site of stimulation, allowing Na+ to rush in. This causes the inside (which was negative) to become positive. Moves toward 0 mV... -If a stimulus causes the membrane to depolarize to the to a critical level, called the threshold (-55 mV), the influx of Na+ becomes so large that membrane potential changes from negative to +30mV. When this occurs, the nerve fiber cannot be stimulated again until repolarization is nearly complete. -repolarization: As the inflow of Na+ slows as the Na+ channel closes, it causes the K+ channels to open, allowing the K+ to flow out of the neuron. This reestablishes the resting membrane potential. action potential - Answer -depolarization of the cell membrane generating an electrical impulse A sequence of rapidly occurring events (either a chemical or physical stimulus) that decrease and eventually reverse the membrane potential (depolarization) and then restore the resting membrane potential (repolarization). This impulse travels along the membrane along the neuron's cell membrane. resting membrane potential and voltage difference (think of ion distributions in and out of cell/active transport) - Answer -the electrical voltage difference across the the membrane of neurons. It is measured in millivolts. (-70mV) Due to a slight buildup of negative charges in the cytosol and an equal buildup of positive charges in the extracellular fluid. This voltage difference is due to the unequal distribution of ions across the plasma membrane and relative permeability of the plasma membrane to Na+ and K+.
-They can synchronize the activity of a group of neurons or muscles (heart or viscera). -Allow two-way transmission of impulses, unlike chemical synapses. Chemical - true gap The presynaptic and postsynaptic neurons are separated by the synaptic cleft filled with extracellular fluid. Pulses cannot jump the cleft, so there must be an alternate way to cross this space. This is done with neurotransmitters that are released by the presynaptic neuron, diffuse across the synaptic cleft, and act on receptors in the membrane of the postsynaptic neuron. -unidirectional -1. As the nerve impulse reaches the synaptic bulb of the presynaptic neuron, depolarization causes Ca2+ channels to open (in addition to the Na+ channels).
- Because Ca2+ is more concentrated in the extracellular fluid, the Ca2+ flows into the presynaptic neuron.
- The increase in Ca2+ causes the synaptic vesicles to undergo exocytosis and release their neurotransmitters into the synaptic cleft.
- The neurotransmitters diffuse across the synaptic cleft and bind to the neurotransmitter receptors in the postsynaptic membrane. neurotransmitters -most important? -how are they recylced -types - Answer --The neurotransmitters can either cause the postsynaptic neuron to be excited and therefore bring the postsynaptic neuron's membrane closer to the threshold, or they can inhibit the postsynaptic neuron's membrane from reaching its threshold. -Neurotransmitters can be recycled by actively being transported back into the neuron that released them (norepinephrine), or they can linger in the synaptic cleft and produce excessive stimulation (dopamine). -acetylcholine: neurotransmitter found in both central and peripheral nervous system especially important in acting as the signal for muscle contraction -without signal, fails to contract
-blocker: insecticides -lack of ability to move prevent the insect from being a pest, block neurotransmitters and prevent depolarization of the muscle membrane. -overexposure of a mammal to a pesticide can block functions like respiration and kill the animal we intend to protect. divisions of nervous system - Answer -CNS- brain and spinal cord PNS- somatic (voluntary- cranial and spinal) and autonomic (involuntary-sympathetic and parasympathetic) autonomic nervous system -dorsal/ventral root -receptors - Answer --involuntary -Regulates the activity of smooth muscles, cardiac muscles and some glands. The sensory components of the ANS consist of interoceptors that monitor body functions such as carbon dioxide levels in the blood or stretching of organs and blood vessels. These signals are not usually perceived as conscious unless they give rise to sensations such as nausea, a full urinary bladder, or angina pectoris (chest pain). -sensor nerves which carry information to the CNS via cranial nerves (to be discussed below) or the dorsal side (referred to as dorsal root) of the spinal column and motor nerves which carrier impulses out to the body via the cranial nerves or the ventral side of the spinal column (ventral root cerebrospinal fluid -produced by -where is it located -functions - Answer -A clear fluid produced by the Choroid plexuses - in brain (a capillary network that extends into the ventricles). It flows through the ventricles, central canal, and subarachnoid space. It surrounds the brain and spinal cord to act as a shock absorber. -cell-free fluid that surrounds the CNS which serve as both a cushion and diffusion media for that tissue -located in meninges -This type of swelling or injury to the CNS termed a concussion, -the cerebrospinal fluid absorbs the energy associated with the potential injury and protects the CNS from harm.
Sensory neurons convey information from the special senses (vision, hearing, taste, smell, and equilibrium) via proprioceptors (muscle and joint position) and general somatic receptors. All of these sensations are consciously perceived. -info about environment and own anatomy The motor neurons of the SNS innervate the skeletal muscles and produce conscious, voluntary movements. These neurons are always excitatory. -includes cranial and spinal nerves cranial nerves -mnemonic? -practice- know all - Answer -The first two originate exterior to the brain and carry signals unidirectionally into the brain. The remained ten originate within the brain stem and exit through the skull foramina oh oh oh to touch and feel very good vaginas, ah heaven!
- Olfactory
- Optic
- Oculomotor
- Trochlear
- Trigeminal
- Abducens
- Facial
- Vestibulocochlear
- Glossopharyngeal
- Vagus
- Accessory
- Hypoglossal CN I - Answer -olfactory
function: smell location: Originates in the olfactory mucosa, pass through the olfactory foramina and terminates in the olfactory bulb of the frontal lobe of the cerebrum -between nose and brain CN II - Answer -optic function: vision Location: Originates in the retina, passes through the optic foramen, forms the optic chiasm, passes through the optic tracts, and terminates in the thalamus. From the thalamus, projections extend into the visual areas in the occipital lobe of the cerebral cortex. -between eye and brain CN III - Answer -Oculomotor Location: Motor - originates in the mesencephalon (midbrain), pass through the superior orbital fissure (space in skull), and is distributed to the superior rectus, inferior rectus, medial rectus , inferior oblique, ciliary muscles, and pupillary sphincter (muscles around eye) Sensory - proprioceptors in the eye muscles. Function: Motor - eyeball movement, constriction of the pupil, and accommodation of lens for near vision. Sensory - muscle sense. CN IV - Answer -Trochlear Location: Motor - originates in the mesencephalon (midbrain), passes through the superior orbital fissure (gap in skull), and is distributed to the superior oblique (eye muscle). Sensory - proprioceptors in the superior oblique muscle pass through the superior orbital fissure and terminate in the mesencephalon.
CN VII - Answer -Facial Location: Motor - originates in the pons, passes through the stylomastoid foramen (hole in skull), and is distributed to the facial, scalp, and neck muscles, the lacrimal (tear), sublingual + submandibular (salivary), nasal, and palatine glands. Sensory - originates from the taste buds on the anterior two-thirds of the tongue, passes through the stylomastoid foramen (hole in skull), and terminates in the pons. The pons sends fibers that pass through the thalamus and on to the parietal lobe of the cerebrum. Function: Motor - facial expression and secretion of saliva and tears. Sensory - muscle sense and taste. CN VIII - Answer -Vestibulocochlear Location: Cochlear Branch - originates in the spiral organ (organ of Corti), forms the spiral ganglion, passes through the internal auditory meatus, and terminates in the thalamus. Fibers from the thalamus relay impulses to the auditory areas of the temporal lobe of the cerebrum. Vestibular Branch - originates in the semicircular canals, saccule, and utricle, forms the vestibular ganglion and terminates in the pons and cerebellum. Function: Cochlear branch - hearing. Vestibular branch - equilibrium. CN IX - Answer -Glossopharyngeal Location: Motor - originates in the medulla, passes through the
jugular foramen (hole in skull), and is distributed to the stylopharyngeus muscle (muscle on cheek) and parathyroid gland (in throat). Sensory - originates in the taste buds on the posterior one - third of the tongue and from the carotid sinuses (along throat) passes through the jugular foramen, and terminates in the medulla. There are also proprioceptors in the posterior one - third of the tongue and swallowing muscles. Function: Motor - secretion of saliva. Sensory - taste, regulation of blood pressure, and muscle sense. CN X - Answer -Vagus Location: Motor - originates in the medulla, passes through the jugular foramen (hole in skull), and terminates in the muscle of the airways, lungs, esophagus, heart, stomach small intestine, most of the large intestine, gallbladder, and glands of the gastrointestinal tract. Sensory - originates from the same structures, passes through the jugular foramen, and terminate in the medulla and pons. Function: Motor - smooth muscle contraction and relaxation and secretion of digestive fluids. Sensory - sensations from visceral organs and muscle sense. CN XI - Answer -Accessory Location: Motor - Cranial portion originates from the medulla,
Cervical C1-C3 Neck C4- Diaphragm C5-T1 Front Limbs Thoracic T2-T12 Intercostals T7-L1 Abdominals T11-L2 Ejaculation Lumbar L2-S1 Hind Limbs Sacral S2 Penile Erection S2-S3 Bladder and Bowel reflex arc -monosynaptic vs polysynaptic -different effectors - Answer --a "short circuiting" of sensor and motor nerves in the spine to allow rapid response to stimulation The most basic nerve pathway in the body that connects a receptor and effector. It consists of a receptor, a sensory neuron, an integrating center in the CNS, a motor neuron, and effector. Receptors are the distal end of the sensory neurons and respond to a stimulus. The nerve impulse travels to axon terminals in the CNS. The impulse travels to an integrating center. This can be as simple as a\ synapses between the sensory and motor neuron (monosynaptic) or involve one or more interneurons (polysynaptic). The impulse triggered by the integrating center travels along a motor neuron to an effector.
The effector is the part of the body that responds to the impulse.If the effector is a skeletal muscle, the reflex is a somatic reflex. If the effector is a smooth muscle, gland, or cardiac muscle, it is an autonomic reflex In most cases, we think of sensory impulses coming from the body via the PNS, entering the CNS, and going to the brain for interpretation. The brain will then send a response down the CNS to the PNS, and activate muscle groups accordingly. But sometimes, the amount of time necessary to make this circuit would allow significant injury to the tissue (think putting your finger in a flame or an animal backing into a hotwire fence). In these cases, a short circuit is possible; sensor impulses from affected tissues send a signal up the PNS through the dorsal root of the spine. Rather than the impulse continuing to the brain, the intensity of the stimulus causes the impulse to "jump" to the motor nerves on the ventral side, which sends an impulse to muscles, causing contractions and moving the tissue out of harm's way energy and senses - Answer -sight- radiant energy sound - pressure (air for hearing, gravity for equilibrium) touch - radian energy, pressure, chemical smell - chemical taste - chemical vision - part 1 (to retina) - Answer -Once light bounces off an object and is reflected toward the animal, it will be seen if it strikes the eye. In the eye, light will first strike and pass through the cornea. From there, adjustments will be made to the iris to permit the right amount of light to continue on through the pupil and lens. Too much light passing through them would cause everything to appear washed out and white, with little detail. Too little light would make the image dark with little detail. Then light will strike the lens, which is designed to focus a sharp image on the back of the eyeball at the retina. However, prior to hitting the retina, light must be passed through the fluid-filled center of the eyeball called the Vitreous Humor. At each of these junctions, light is refracted, so that it is slightly at an angle compared to the path at which it hit the cornea. Further, because the light passes through the lens, the image is flipped one- hundred-eighty degrees vision (part 2) - photopigments -systems in cerebral cortex? - Answer -Once light reaches the retina, it will strike the Photopigments
-As the light enters the eye, it is refracted at both the anterior and posterior surfaces of the cornea. Both surfaces of the lens further refract the light, focusing the image on the retina. Lens: Fine-tunes the image and changes the focus for near or distant objects. accomodation of lens -near point of vision -term? - Answer -allows reshaping of the eyeball to allow shape focused near or up-close vision. -When the eye is focusing on a near object, the lens curves more to bend the rays toward the central fovea. -Near Point of Vision: minimum distance of 10cm (4 in.) in a young adult -As we age the lens loses elasticity and, therefore, its ability to accommodate. This is called presbyopia (gradual loss of your eyes' ability to focus on nearby objects) 4 terms for eyes - Answer -Emmetropic eye: normal eye with object at 20ft (6m) focused clearly - 20/ vision Myopia: nearsighted Hypermetropia: farsighted Astigmatism: irregularities of the surface of the lens nerves and special senses - Answer -vision : CN II -optic hearing : CN VIII -vestibulocochlear - vestibular (balance) and cochlear (hearing) smell : CN I - olfactory taste : Facial Nerve (VII), the Glossopharyngeal (IX), or the Vagus (X) hearing - read over - Answer -Step One: The auricle directs sound into the external auditory meatus. Step Two: Sound waves strike the eardrum and cause it to vibrate. It vibrates slowly in response to low- frequency (low-pitch) sound and rapidly to high-frequency (high-pitch). Step Three: Because the malleus is connected to the eardrum, it also starts to vibrate. The vibrations are then transmitted through the inus to the stapes. Step Four: As the stapes vibrates it the oval window. The oval window vibrates ~ 20 times more vigorously than the eardrum.
Step Five: The movement of the oval window sets up fluid pressure waves in the perilymph of the cochlea. Step Six: The perilymph flows toward the scala vestibuli. The pressure waves are transmitted from the scala vestibuli to the scala tempani and eventually to the round window. Step Seven: As the pressure deforms the walls of the scala vestibuli and scala tympani, they push the vestibular membrane back and forth. This results in the pressure of the endolymph in the cochlear duct to increase and decrease. Step Eight: The pressure fluctuations cause slight vibrations in the basilar membrane, which causes the hair cells in the spiral organ to move against the tectorial membrane. The bending of the microvilli (hair cells) leads to the generation of a nerve impulse in the cochlear nerve fibers. Step Nine: The impulse is then transmitted via the cochlear branch of the Vestibularcochlear nerve to the thalamus where the pulse is transferred on to the temporal lobe of the cerebrum. hearing pathway - Answer -As with sight, hearing has a mechanical and neurological component. It begins with sound being captured by the outer ear and routed down the outer ear canal to the eardrum (Figure 4). Sound waves strike the ear drum and cause it to vibrate. It vibrates slowly in response to low- frequency (low-pitch) sounds, and rapidly to high-frequency (high-pitch) sounds. The vibrating eardrum will cause the malleus bone to vibrate, then the incus and stapes in turn. The vibration of the stapes bone is 20 times more vigorous than the ear drum. The vibration of the stapes bone will be transferred to the fluid in the cochlear duct in turn, causing the hair lining the canal to vibrate, creating an innervation signal to the cochlear branch of CN VIII. The innervation signal transfers to the thalamus where it is transferred on to the temporal lobe of the cerebrum for interpretation. equilibrium -disruption? - Answer --nonscientific: the ability of an animal to stand upright. -The "sense" of equilibrium uses gravity and a set of hair in the inner ear to tell the body its location. The hair is designed to stand vertically in response to the earth's gravity. As the head tilts, the hair adjusts to stay vertical, bending at the base, triggering the release of neurotransmitters stimulating signals to the brain There are also chemicals that can disrupt equilibrium. Two that are primarily seen in humans are alcohol and anesthetics. In animals, certain toxins in foodstuff and infections can either damage the hair, or disrupt the neurotransmitter signal from the hair to cranial nerves, and cause the animal to lose the ability to detect its location relative to gravity, which, in general, would cause it to have problems standing.
frontal lobe of the cerebrum. The nerve pulse is then transferred on to the temporal lobe and to the frontal lobe, either directly or indirectly through the thalamus. The temporal and frontal lobes then process the signal into what is perceived as an odor. Once, it was thought that there were only seven primary scents, which humans perceived as camphor, musk, floral, peppermint, ether, pungent, and putrid. However, more recent research now suggests that there may be several hundred primary scents. Further, other research has demonstrated that various species have differing numbers of olfactory receptors, with mammalian predators appearing to have the most. taste /gustatory sense -taste buds -papillae -the five primary tastes - Answer -The expression true sense of taste was used here as what we commonly think of as the sense of taste, which actually uses two senses: the sense of taste and the sense of touch. The true sense of taste is what we might call the sense of detecting flavor. As stated above, the innervation of the sense of taste begins with chemical molecules from the food binding receptors on the taste buds. There are roughly 10,000-100,000 tastes bud in mammals (species specific). Most of the taste buds are located on the tongue, but portions are located on the soft palate, pharynx, and larynx. Each taste bud is an oval body made up of between 50 and 500 gustatory receptor cells and a number of supporting cells and forms a capsule (Figure 7). On the tongue, the taste buds are located on the papillae, which increase the surface area several fold over a single flat surface (Figure 8). Besides increasing the surface area, the papillae also create a "gripping" surface which is important for food movement and swallowing. (also grooming) There are basically five primary tastes: sweet, sour, bitter, salty, and umami (from the Japanese for pleasant). Each taste bud has cells for each taste. However, there are regions on the tongue which contain more of a particular type of gustatorial cells taste - pathway -taste and smell? - Answer -Chemicals from the food will dissolve in the saliva and make contact with the taste buds. Specifically, the chemical molecules will bind to the receptors on the gustatory hair (microvillus) that project from the surface of the gustatory receptor cell into the taste pore. Binding stimulates the release of neurotransmitters, which cause an impulse in the sensory neurons. The pathway back to the brain will be depend on the location of the taste bud, as three different cranial nerves; the Facial Nerve, the Glossopharyngeal, or the Vagus, transmit to the cortex.
Further, there is an interaction between the sense of smell and the sense of taste. This is because odors from food will pass through the nasopharynx and nasal cavity, and stimulate the olfactory receptors. Further, a given concentration of a substance will stimulate the olfactory system a thousand times more than the sense of taste. touch /cutaneous sense -functions -what is it process - Answer -The cutaneous sense is the body's main, and most continuous means of communication with its environment. For example, it helps determine BMR by sensing the outside temperature. It also will help prevent bodily injury by sensing when things make contact, and it plays important roles in animal interaction; for example, cutaneous nerves in the penis send signals to the male that he is in the right position during mating, and will lead to ejaculation. What is outlined below is how this very dynamic sense works. -What we would describe as the basic sense of touch is "pressure" exerted on the skin. This pressure could be something as light as brushing against the hair on a limb. Displacement of the hair at its base will interact with the nerve endings, and trigger the release of neurotransmitters from specialized nerve endings. Or, the sensation may be the result of direct contact of a foreign object with the skin (Figure 10). Either way, the impulse may travel either to just the spinal column (see pain below), or to the brain for interpretation. The result of this interaction is what is referred to as tactile nerve innervation. Touch -touch, crude touch, discriminative touch -corpuscles of touch - Answer -Touch: General results from the stimulation of tactile receptors in the skin or tissues immediately under the skin. Crude Tough: the ability to perceive something that has touched the skin, although its exact location, size, shape, or texture cannot be determined. Discriminative Tough: the ability to determine exactly what point on the body is being touched. -The receptors for the two are different, with those for discriminative touch being egg-shaped (corpuscles of touch). They are most plentiful at the fingertips, palms, and soles. They are also abundant in the eyelids, tip of tongue, lips, nipples, clitoris, and the tip of the penis. hair root plexuses type 1 cutaneous mechanoreceptors
