The Nervous System nFunction??? n … the body’s mission control center. n … keep the life-support systems functioning together Cells of the Nervous System n Neurons – the basic unit (cell) of the nervous system. Neurons bundled together are called NERVES. Body n Cell n Dendrites n Axon n Cell Body – Contains nucleus & other cell parts n Dendrites –conducts an impulse toward the cell body. n Axon – conducts impulses away from the cell body. n Schwann cells – a series of enclosed cells that make up the axon. Collectively, these Schwann cells are called the Myelin Sheath. The gap between nerve cells is the synapse. Stimulus à Response Stimulus Response Information A reaction to a received from the condition or a nervous system STIMULUS! To about the survive an condition inside & organism must outside the body. respond to stimuli. How the Nervous System works together What is it? Their Job? Sense organ or To receive a nerve any other organ impulse and send it Receptors sensitive to a through a conductor to stimulus the interpretor. Carries a nerve The axon of the impulse from the Conductors nerve cell receptors to the effectors How the Nervous System works together What is it? Their Job? Takes incoming Inter- messages & makes a The Brain pretor decision and sends out a message. Receives information coming from the brain Effectors Organ or Tissue & responds to a stimulus. The Reflex Arc n Reflexes are automatic, involuntary responses. n A reflex arc involves the following pathway. n Sensory receptors generate an impulse in a sensory neuron that moves along sensory axons toward spinal cord. The Reflex Arc n Sensory neurons enter the spinal cord and pass signals to interneurons. n Impulses travel along motor axons to an effector, which brings about response to the stimulus. n The immediate response is that muscles contract to withdraw from source of pain; the brain does not integrate the sensory & motor activities Reflex Arc Animations Animation #1 Animation #2 Animation #3 The Reflex Arc Chapter 40 Bookwork n Read Chapter 40 (Pg. 939-960) n Answer the following questions n Pg. 943 #1-2 n Pg. 949 #1-5 n Pg. 954 #1-5 n Pg. 961 #1-6 n Be sure to write out QUESTION & ANSWER 2 Basic Parts of the Human Nervous System n Central Nervous System (CNS) n Made up of the brain & spinal cord. The control center; coordinates body activity. n Peripheral Nervous System (PNS) n Made up of the nerves that carry messages to and from the central nervous system. Peripheral Nervous System n Somatic Nervous System – voluntary responses (ex. Walking, running). n Autonomic Nervous System – involuntary responses (ex. Glands in stomach produce enzymes to break down protein). n Sympathetic Nervous System n Parasympathetic Nervous System Autonomic Nervous System n Sympathetic Nervous System – controls internal functions during times of stress. “Fight or Flight” n Parasympathetic Nervous System – controls internal functions of the body at rest. “Rest & Digest” Central Nervous System n Cerebrum – conscious activity; memory, language and the senses. The Lobes of the Cerebrum Lobes of the Cerebrum n Frontal Lobe - Speech production, the elaboration of thought and emotion, and skilled movements are controlled by neurons found in this part of the brain. n Temporal Lobe – Hearing & Tte recognition of specific tones and loudness takes place here. This area also plays a role in memory storage. Lobes of the Cerebrum n Parietal Lobe - A variety of bodily sensations such as touch, pressure, pain and temperature are all perceived and interpreted here. n Occipital Lobe - The neurons in the occipital lobe interpret nerve impulses from the eyes. Central Nervous System n Cerebellum – balance, posture & coordination. n Thalamus – receives and sends sensory signals to the cerebrum. Central Nervous System n Hypothalamus – regulation of heart rate, blood pressure, body temperature, water balance; hunger, thirst and sleep; serves as a link between the nervous and endocrine system. n Medulla Oblongata – controls involuntary activities such as breathing, heartbeat, swallowing & sneezing. The Eye n 90% of our information comes through the sense of sight. The eye is made up of 3 layers: n Outer Layer – Sclera n Middle Layer – Choroid n Inner Layer - Retina The outer layer of the Eye - Sclera n Cornea: The transparent area of the sclera located at the front of the eye. The middle layer of the Eye Choroid n Iris: regulates the amount of light entering the eye. It is pigmented and surrounds the pupil which is a hole. n Lens: A transparent protein disc that is used to focus light onto the retina. Its shape is controlled by… n Ciliary muscles: Controls the shape of the lens. The inner layer of the Eye Retina The Retina is the inner most layer of the eyeball. It contains photoreceptor cells that transmit signals to the optic nerve. n Rods and Cones: Rods are sensitive to light but do not distinguish colors, where as cones are responsible for daytime color vision. The inner layer of the Eye Retina n Fovea: Area of the retina that contains the highest concentration of cones. Does not contain any rods. This is where an object comes into focus. n Optic nerve: Nerve that connects the eye to the brain. n Blind spot: Area of the eye that does not contain any rod or cones. It is here that the eye is attached to the optic nerve. The Fluids of the Eye n Aqueous Humor: fluid behind the cornea and in front of the lens. Helps focus light onto the retina. n Vitreous Humor: fluid that fills the large central chamber of the eye. It helps focus light onto the retina. The Ear n The ear maintains both hearing and balance. The structures for these sensory functions are located in separate areas of the inner ear. The Outer Ear n The Pinna, which is the visible part of the outer ear, funnels sound waves into the outer ear canal. n The waves travel to the eardrum and cause it to vibrate. The Middle Ear n This air-filled portion of the temporal bone lies between the eardrum and the inner ear. n The malleus, incus and stapes are bones that transfer sound vibrations from the eardrum to the inner ear. The Inner Ear n The inner ear consists of a complex system of membranous canals. n The hearing organ is located in the snail-like cochlea. n The sense of balance operates from the structures in the vestibule and semicircular canals.
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