2 Cells of the Nervous System NeuronsDendritesAxonsSchwann cellsSynapseSupporting cellsGlial cellsAstrocytesOligodendrocytes.Neurons: Contain a relatively large cell body containing the nucleus, cytoplasm, and all the major organelles.Dendrites, a cell process that conducts impulse toward the cell body. Axons, a cell process that conducts impulses away from the cell body.Axons usually contain a series of enclosing cells called Schwann cells. Collectively these Schwann cells are called the myelin sheath. Axons may be branched and end up in structures called synaptic knobs. The gap between nerve cells is the synapse.The cells bodies are located in the central nervous system.( brain and spinal cord). The cell bodies of certain nerves cluster outside of the spinal cord in aggregates called ganglia. These and the axons make up the peripheral nervous system. The major types of neurons of this system are: sensory and motor. They are connected to the central nervous system by structures called interneurons.Supporting cells: these cells outnumber neurons to one. They do not conduct impulses but are needed for the physical integrity of the system. Glial cells, Astrocytes and oligodendrocytes.
3 Central vs. Peripheral Nervous System Cell bodies = central nervous system(brain and spinal cord)GangliaGanglia + axons = peripheral nervous system
4 Interneurons – connect peripheral neurons with CNS neurons Types of NeuronsSensoryMotorInterneurons – connect peripheral neurons with CNS neurons
5 Transmission Along Neurons The Resting Potential:Cell membrane is negative (polarized).Membrane stores energy by holding charges apart.Positive outside and negative inside.Resting potential of a cell = -70 millivolts
6 Transmission (cont.) Sodium-potassium pumps on membrane ATP drivenChange in resting potential = a stimulusIf stimulus depolarizes cell = Action PotentialThe action potential is an all or none eventA neuron has a threshold potential -50 millivolts
7 The Brain Contains cavities (ventricles) Cerebrospinal fluid (CSF) Meninges – 3 tough layers that protect brain and spinal cordDura materArachnoid materPia mater
8 Central Nervous System (CNS) 1. Medulla Oblongata - controls involuntary and visceral activities.2. Cerebellum - controls body balance, muscular coordination and equilibrium.3. Hypothalamus - maintains the internal environment.4. Thalamus - Sorts out and relays the incoming and outgoing impulses.5. Cerebral cortex - center of all voluntary muscular control and mental activity1. Medulla Oblongata: through the autonomic nervous system, controls involuntary and visceral activities.2. Cerebellum: controls body balance, muscular coordination and equilibrium.3. Hypothalamus: regulates body temperature, thirst, hunger, metabolism, pleasure, pain, sex, and rage ( in general it maintains the internal environment).4. Thalamus: The center that sorts out the thousands of incoming and outgoing impulses and relays them to the various brain centers.5. Cerebral cortex: center of all voluntary muscular control and mental activity. centers of analysis, coding, storage of information, recognition, memory, understanding,intelligence and sense integration are located here.The brain is not a solid structure; it contains cavities called ventricles which contain a liquid called cerebrospinal fluid. The brain and spinal cord are covered by three layersof tough material called meninges.
9 Autonomic Nervous System Control of the involuntary muscles2 separate partssympatheticparasympathetic
10 Sympathetic vs. Parasympathetic HeartSlows downSpeeds upArteriesDilates (opens)ConstrictsDigestive OrgansSpeeds up peristalsisSlows down peristalsisBronchial MusclesDilatesSweat GlandsDecreases actionIncreases action
12 Parts of the Eye Cornea - protection Aqueous Humor - helps focus light onto the retinaIris - regulates amount of light entering the eyeLens - focuses light onto the retinaVitreous Humor - helps focus light onto the retina
13 Parts of the Eye (cont.) Retina - transmit signals to the optic nerve Rods and Cones - sense to lightFovea - contains the highest concentration of conesOptic nerve - connects the eye to the brainBlind spot – no receptors, the eye is attached to the optic nerve here
15 Parts of the Ear Pinna – gathers sound Outer ear - connects outer ear with ear drum (tympanic membrane)Tympanic membrane - transmits sound waves to three tiny bonesHammer, anvil, and stirrup (middle ear) - send impulses to the oval window of the cochlea.Semicircular canals (inner ear) – balanceCochlea - change sound waves into nerve impulses