-Nervous System 3 functions of the nervous system: -Receives and relays information -Monitors and responds to internal and external changes -Controls and coordinates all body functions Sensory: become aware of stimuli: change in environment Integative: memory, emotions, conscience, decisions Response: muscles, what did you do? Neuron- (nerve cell) cells that carry messages throughout the nervous system Nerve impulse- electrical signals, coded method from neuron Sensory neuron: neuron that carries impulses from the sense organs to the brain and spinal cord Motor neuron: neuron that carries impulses from the brain and spinal cord to muscles and glands Interneuron: cell that connects the motor and sensory neurons (only found in brain) Cell body- center part of the neuron that contains the nucleus and much of the cytoplasm Dendrite- part of the neuron that is an extension from the cell body of a neuron that carries impulses from the environment to the cell body Axon- long fiber that carries impulses away from the cell body of a neuron Axon terminals- small swellings in a neuron at the end of an axon that makes connections with next neuron Myelin- substance composed of liplids and protein that forms an insulated sheath around an axon, and makes a better impulse Neurilemma- outermost covering of a neuron allows nerve to grow back Threshold stimulus- minimum level of a stimulus required activating a neuron Receptor- special sensory neuron in a sense organ that receives stimuli from external environment (nose, eyes, ears) Effector- muscle of gland that brings about a coordinated response to a stimuli Synapse- point of contact at witch an impulse is passed from one cell to another Neurotransmitters- substance used by one neuron to signal another -Eye Sclera- white part of the eye that helps maintain the shape and provides muscle that moves the eye Choroid- pigmented, contains blood vessels of eye, and becomes the disk-like structure called the iris Iris- part of the eye that gives it its color Pupil- in the middle of the iris, small opening light enters here, (black disk) Retina- innermost layer of eye contains photoreceptor cells (rods, cones) Rods- photoreceptor cells, really sensitive to color of light, DONT detect colors Cones- photoreceptor cells, gives us color vision Conjunctiva- transparent coat on outside of eye (pink eye) Cornea- outer, part of eye where light enters transparent layer Lens- part of eye you see out of, it focuses things Suspensory Ligaments- holds lens in place Ciliary Body- allows us to focus close-up Vitreous Humor- behind lens, filled with transparent jelly fluid, keeps eye rounded Aqueous Humor- inside cornea filled with fluid keeps cornea rounded shape Optic nerve- nerve cell carries information to brain for interpreting Fovea- cells are cones, can see color and bright light Myopia- near sided, long strong Hyperopia- far sided, short weak -Spinal Cord and Brain 2 major divisions of the nervous system: -Central: control center, consists of brain and spinal cord, relays messages, processes information, compares and analyzes information -Peripheral: outside the central, all nerves, receptors, and ganglions The cerebrum has a left and a right hemisphere; it is the biggest part of the brain. Fissures- valleys on the brain Convolutions- ridges on the brain Lobes- regions of the brain Cerebral Cortex- gray matter on the surface of the brain Functions include: voluntary muscles/activities, instincts, behavior, intelligence, emotions learning, memory, and senses The cerebellum coordinates muscle actions Brain Stem- structure that connects the brain with the spinal cord and is composed of the medulla, pons, and mid-brain, coordinates information coming into brain Medulla Oblongata- contains white matter that conducts impulses between spinal cord and brain, controls involuntary functions such as; breathing, blood pressure, swallowing, coughing, and heart rate Pons- contains white matter that provides link between the cerebral cortex and cerebellum Mid-brain- involved with hearing and vision reflex Thalamus- gray matter, serves as the switching station for sensory input, passes information to the proper region Hypothalamus- serves as the control center for hunger, thirst, fatigue, anger, and body temperature EGG- electroencephalogram, shows activities of the brain Short-term memory- only last a few days, such as what you had for breakfast Long-term memory- memories that are permanent and last a long time Structure of the spinal cord: Acts as a communications link between the brain and the peripheral nervous system. Carries impulses and regulates reflexes. (2 types of nerve tissue) What are ways in which the brain and spinal cord are protected? Bone-hard over-top of the brain and spinal cord Meninges- membranes on surface of brain and spinal cord protect against rubbing Cerebrospinal fluid- surrounds brain and spinal cord and acts as shocks or cushions Peripheral Nervous System: takes information and sends it to the brain and spinal cord and back (31 pair of vertebrate nerves, 31 pair of spinal nerves, and 12 pair of cranial nerves) Parts of the Peripheral Nervous System: Somatic- regulates activities we have control over such as moving, talking, running, and jumping Autonomatic- regulates activities we dont have control over such as digestion, breathing, and heart rate What is a reflex arc? -Path that an impulse will travel during a reflex 3 parts of the reflex arc: -Sensory neuron -Interneuron -Motor neuron -Ear Auricle- outside ear, channels sound waves into ear Auditory Canal- contains small hairs and wax producing glands (then sound waves go to eardrum) Eardrum- the beginning of the middle ear Malleus-tiny bone Incus- tiny bone, transfers sound from the outer ear to the inner ear Stapes- tiny bone, transfers sound from the outer ear to the inner ear Eustachian tube- mid ear, where yawn air comes in and out or swallow, also transfers sound from the outer ear to the inner ear Oval window- transmits the vibrations to the cochlea Cochlea- begins the inner ear, snail shaped cavity full of fluid Acoustic nerve- carries impulses from cochlea to brain where we hear Semicircular canals- 3 canals that lie at right angles, sense of balance Compare senses of taste and smell: Chemoreceptors detect taste and smell Olfactory receptors: detect smell Taste buds: detect taste with saliva (found on lips, roof of mouth, and tongue) 4 types of tastes: -Sour -Sweet -Salt -Bitter Cerumen: ear wax, prevents anything from getting into direct contact with eardrum, and also keeps eardrum soft and flexible Sound: Pitch: high or low a sound is Quality: a persons voice, unique to each others, (telling the difference) Loudness: loud or soft a sound is
