Nervous System Class Notes PDF

# Chapter 17: Nervous System ## Chapter Outline - Nervous Tissue - Transmission of Nerve Impulses - The Central Nervous System - The Limbic System and Higher Mental Functions - The Peripheral Nervous System ## Learning Objectives By the end of this unit, you should be able to: - Describe the stru...

# Chapter 17: Nervous System ## Chapter Outline - Nervous Tissue - Transmission of Nerve Impulses - The Central Nervous System - The Limbic System and Higher Mental Functions - The Peripheral Nervous System ## Learning Objectives By the end of this unit, you should be able to: - Describe the structure and function of the nervous system - Identify two anatomical divisions of the nervous system - Identify the parts of a neuron - Understand the structure/function of the different classes of neurons - Differentiate between neuroglial cells of the central nervous system and peripheral nervous system - Understand the major regions of the brain - Know the structure/organization of the spinal cord - Describe the somatic reflex arc & identify the parts of the nervous system involved in the reflex arc. - This unit will help you achieve the following Course Learning Outcomes (CLO): - CLO1-Analyze, using many modes of communication (and/or verbal), the crucial contribution of homeostasis to human body function using the language of medicine. - CLO2- Distinguish various tissues, muscles and membranes within the human body. - CLO4 - Describe the physiology of each of the body's organ systems using the language of medicine. ## Overview of this Section ### Anatomy of Neuron A diagram of a neuron is provided. The diagram highlights the following parts: - Cell body (soma) - Dendrites - Axon - Myelin sheath - Node of Ranvier - Axon terminal ### Classes of Neuron A diagram of a neuron is provided. The diagram highlights the following parts: - Cell body - Axon - Dendrite - Myelin sheath - Node of Ranvier - Axon terminal ### Electrochemical Synapse A diagram of a synapse is provided. The diagram highlights the following parts: - Presynaptic neuron - Postsynaptic neuron - Synaptic cleft ## Functions of the Nervous System - Receives sensory input - Integrates and stores input - Initiates motor output - Helps coordinate organ systems ## The Nervous System - Two Anatomical Divisions - **Central Nervous System (CNS)** - Brain and Spinal Cord - **Peripheral Nervous System (PNS)** - Cranial nerves and spinal nerves ## Body Membranes Supporting Body Systems - **Meninges** - Membranes in the dorsal cavity. - Protects the brain and spinal cord. - Secretes cerebral spinal fluid. ## Nervous Tissue - Nervous tissue is composed of: - **Neurons** - Conduct electrical nerve signals/impulses ## Anatomy Of a Neuron - **Parts of a Neuron** - **Dendrites** - Extensions that pick up the signals from the surroundings and adjacent cells and send those impulses to the cell body - **Cell body** - Contains the nucleus and other organelles. It processes the incoming signals. - **Axon** - Conducts nerve impulses away from the cell body. - **Myelin** - Lipid-based covering around axon, present in some neuron - **Node of Ranvier** - In myelinated neurons, these are regions of axon free of myelin - **Axon Terminal** - Ends of the neuron, used in communication with other neurons or effectors (muscle and/or gland) ## From Structure to Function ## Neurons-Conduct Nerve Impulses - The nerve impulse requires a membrane potential - What is a Membrane Potential? ## Membrane Potential - Membrane potential is a difference of electrical charges due to ions present on the inside and outside of the cell. ## Generating Membrane Potential - Requires Integral Membrane Proteins ## 3 Types of Integral Membrane Proteins are Required - **Channels** - **Carriers** - **Pumps** ## Terminology - **Depolarization** - Reducing the negative charge - Making the inside more positive - **Repolarization** - Bringing back the negative charge - Making the inside more negative ## Let's look at the stages for achieving an electrical impulse A diagram of a neuron is provided. The diagram highlights the following events: - **Depolarization** - Occurs when the soma end of the axon becomes depolarized. - **Repolarization** - Occurs when the first part of the membrane repolarizes. - **Resting Potential** - The membrane cannot depolarize again. ## Saltatory Conduction - A diagram of saltatory conduction is provided. ## There are 3 Classes of Neurons - **Sensory Neurons** - A.k.a. afferent neurons - Takes messages from the environment to the CNS - **Interneurons** - Always in the CNS - Receive input from sensory neurons and other interneurons - Summarize messages - Communicate with motor neurons - **Motor Neurons** - A.k.a. efferent neurons - Carries messages from the CNS to an effector ## Identify: 3 Types of Neurons - **Sensory Neurons** - **Interneurons** - **Motor Neurons** ## How is the information passed from Sensory → Interneuron → Motor neuron? ## Electrochemical Synapse - An electrochemical synapse is a communication junction between neurons ## Electrochemical Synapse A diagram of a synapse is provided. The diagram highlights the following events: - Nerve Impulse/Action Potential (AP) reaches the axonal terminal. - Channels open in response to AP. - Calcium influx causes synaptic vesicles, containing neurotransmitters (NT), to fuse with the neuronal membrane. - NTs release into the synaptic cleft. - NTs bind to the receptors on the postsynaptic neuron. - If enough Na+ flows to cross the threshold barrier of the postsynaptic neuron, then AP will occur to the end of the postsynaptic neuron. ## The Nervous System - Two Anatomical Divisions - **Central Nervous System (CNS)** - Brain and Spinal Cord - **Peripheral Nervous System (PNS)** - Cranial nerves and spinal nerves - Neurons are busy cells… but how are they supported within the two divisions of the Nervous System?