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Nervous System and Eye Dissection

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Nervous System and Eye Dissection Nervous System and Eye Dissection • Monday 10th Thursday 13th • Take notes on Slides 3 - 8 • Take notes on Slides 12-16 • Introduction to Nervous System • Notes for lab on Monday • Brain Metaphor Activity • Mechanoreceptors and • Quiz Each other on notes Thermoreceptors • Tuesday 11th Friday 14th • Guest Speaker • Finish notes • Take Quizziz on Nervous System th • Wednesday 12 • Take Quizziz on Senses and Eyes • Take notes on slides 9-11 and Eye • Study Word Parts and Eye Dissection Dissection PowerPoint (Online) Terms • Nervous System • Senses 1. Draw neuron , label parts, and functions 2. Quiz Self of Nervous Cell and Functions 3. http://myclass.theinspiredinstructor.com/science/health_diagrams/ Neuron_Label.htm The Nervous System is divided into two parts: 1. Central NS a. Brain and spinal cord b. Processes info 2. Peripheral NS a. Mainly of nerves, sense organs b. Connect the CNS to every other part of the body c. Receives/sends info to and from the body 3. Nerves that transmit signals from the brain are called motor or efferent nerves 4. Nerves that transmit information from the body to the CNS are called sensory or afferent. Central Nervous System •Cerebrum •Frontal •Parietal •Occipital •Temporal •Cerebellum •Brain Stem Peripheral Nervous System Divided into three parts: 1. Somatic Nervous System (SNS) 1. Voluntary Movement (consciously control) 2. Example: Skeletal muscles 2. Autonomic Nervous system (ANS) 1. Functions involuntarily (Do not consciously control) 2. Example: Smooth and cardiac muscles 3. ANS - divides into Sympathetic and Parasympathetic Nervous System 1. Sympathetic – activated in cases of emergencies to mobilize energy 2. Parasympathetic – Normal , resting , relaxed state (breathing , digestion) 3. Enteric Nervous System (ENS) 1. Controls the gastrointestinal system 2. Functions involuntarily Autonomic Nervous System Wednesday 12 •Take notes on Slide •Go to Eye Dissection PowerPoint on website and take notes on eye •Quiz partner on words to know for the eye The Iris • Regulates the amount of light entering the eye so that there is enough light to stimulate the cones, but not enough to damage them • By contracting and relaxing these muscles the pupil can be constricted and dilated In bright light the muscles In dim light muscles relax, contract, pupil constricts, and pupils dilate, and more light less light enters eye enters. Thursday 14th •Read and take notes on slides - Information will be in Monday’s lab •Study word parts and eye terms for quiz Tuesday • Must be able to define majority of eye terms to participate in dissection Wednesday Mechanoreceptors and Thermoreceptors The skin has numerous mechanoreceptors that respond to pressure and vibration and thermoreceptors that respond to temperature. When adequately stimulated, the receptors convert the mechanical or heat stimuli into electrical signals that travel along axons to the brain or spinal cord for interpretation. Some areas of the skin are more sensitive to touch than others. The level of sensitivity depends on receptor density and the size of the receptive field. The receptive field is the area where a stimulus will cause a neuron to fire. For example, the receptive field of a mechanoreceptor in the skin is the patch of skin that particular neuron responds to. Large receptive fields allow a neuron (receptor) to sense changes over a large area but without much precision. In the most sensitive areas of the body, there is a high density of mechanoreceptors with small receptive fields. Desensitization and Thermoreceptors • Our hands—especially our fingertips—are well equipped to collect sensory information from the environment surrounding them. They contain an immense number of sensory receptors. External circumstances, such as temperature, texture and touch prompt these receptors to produce electrical signals. The signals travel via a sensory nerve along the arm to the brain where they are processed, compared to past experiences and finally labeled. • Each receptor is triggered by a specific stimulus. Thermoreceptors detect temperature changes. We are equipped with some thermoreceptors that are activated by cold conditions and others that are activated by heat. Warm receptors will turn up their signal rate when they feel warmth— or heat transfer into the body. Cooling—or heat transfer out of the body—results in a decreased signal rate. Cold receptors, on the other hand, increase their firing rate during cooling and decrease it during warming. • Something interesting happens when your expose receptors to a specific sensation such as heat for a long time: they start to tire out and decrease their activity, thereby you will no longer notice the sensation as much. This desensitization could also alter our sensitivity to what we feel next. Two Point Discrimination: • The two-point discrimination test reveals the ability of the somatosensory system to determine if the skin is being touched in one or two points. If the two points are in an area of skin that has a low touch receptor density and large receptive fields, only one point may be perceived. If the two points are in an area of skin that has a high touch receptor density and small receptive fields, the subject may perceive those two points. That is, two stimuli are perceived as separate if they are stimulating the receptive fields of two different mechanoreceptors. .
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