Anatomy & Physiology Lecture Notes PDF

Anatomy & Physiology – Lecture (Nursing) Module #9 Student Activity Sheet Name: _________________________________________________________________...

Anatomy & Physiology – Lecture (Nursing) Module #9 Student Activity Sheet Name: _________________________________________________________________ Class number: _______ Section: ____________ Schedule: ________________________________________ Date: ________________ Lesson title: NERVOUS SYSTEM (Part 1) Learning Targets: At the end of the module, students will be able to: 1. List the major functions of the nervous system; Materials: Book, pen and notebook 2. Define each division & subdivisions of nervous system; 3. Identify the types of cells that make up the nervous system with its structure and function; 4. Describe the myelin sheath and its relationship to the organization of nervous tissue; 5. Distinguish the electrical signals of nervous system that include resting membrane potential, action potential, synapse, and reflexes; 6. Describe the neuronal pathways and its significance with summation; References: 7. Define the structural and functional components of spinal VanPutte, C., Regan, J., & Russo, A. cord, spinal nerves, and spinal reflexes; and, (2019). Seeley’s essentials of anatomy & 8. List the structural and functional components of each major physiology (10th ed.). New York, NY: region and part of the brain. McGraw-Hill Education. A. LESSON REVIEW/PREVIEW Let us have a quick review in the previous lesson. For the words listed below, define them using less than 5 words, one-word description is accepted, too. Just simply write whatever information pops out from your mind after reading the item. This will serve as your assessment for quick grasp to the idea of the word presented. Here’s an example for you: Tendon – bone to muscle. Have fun! 1. Agonist – ___________________________________________________________ 2. Fusiform – ___________________________________________________________ 3. Sternocleidomastoid – ___________________________________________________________ 4. Quadriceps Femoris – ___________________________________________________________ 5. Bulbospongiosus – ___________________________________________________________ B. MAIN LESSON You must read & study the concepts and refer to figures/tables in Chapter 8 of the book. Major Functions of Nervous System: 1. Receiving of sensory inputs 4. Maintaining homeostasis 2. Integrating information 5. Establishing and maintaining mental activity 3. Controlling muscles and glands Main Divisions of the Nervous System: (Refer to Figure 8.1, page 193 of the book) 1. Central Nervous System (CNS) – consists of the brain and spinal cord 2. Peripheral Nervous System (PNS) – consists of all the nervous tissue outside the CNS (nerves & ganglia) This document is the property of PHINMA EDUCATION 1 of 9  Anatomy & Physiology – Lecture (Nursing) Module #9 Student Activity Sheet Name: _________________________________________________________________ Class number: _______ Section: ____________ Schedule: ________________________________________ Date: ________________ ▪ Sensory Division / Afferent Division: conducts action potentials from sensory receptors to CNS by sensory neurons ▪ Motor Division / Efferent Division: conducts action potentials from the CNS to effector organs, such as muscles & glands by motor neurons o Somatic Nervous System – innervates skeletal muscle; mostly under voluntary control o Autonomic Nervous System – innervates cardiac muscle, smooth muscle, and glands; mostly under involuntary control 1. Sympathetic Division 2. Parasympathetic Division ▪ Enteric Nervous System (ENS): unique subdivision of PNS that has both sensory and motor neurons contained wholly within the digestive tract. Cells of the Nervous System: 1. Neurons / Nerve Cells – receive stimuli, conduct action potentials, & transmit signals to other neuron or effector organs; has three parts: ▪ Cell Body: contains a nucleus and processes stimulus ▪ Dendrites: extensions of the neuron cell body; receive stimulus from other neurons or sensory receptors ▪ Axon: single long process; transmits stimulus to a gland, muscle, organ, or other neuron 2. Glial Cells / Neuroglia – supportive cells of CNS & PNS; do not conduct action potentials; carry out different functions that enhance neuron function and maintain normal conditions. Types of Neurons & Glial Cells (See table 8.1, page 195 and figures 8.4 & 8.5, pages 195-196) Myelin Sheaths – fatty, protective wrapping around axons of some neurons that are formed by oligodendrocytes (CNS) and Schwann cells (PNS); serve as an excellent insulator that prevents almost all ion movements across cell membrane ✔ Nodes of Ranvier: gaps in the myelin sheath where the ion movement occurs & action potential develops Organization of Nervous Tissue: 1. Gray Matter – consists of groups of neuron cell bodies & their dendrites, where there is very little myelin ▪ Cortex – located on the surface of brain ▪ Nuclei – clusters of gray matter located deeper within the brain ▪ Ganglion – a cluster of neuron cell bodies in PNS 2. White Matter – consists of bundles of parallel axons with their myelin sheaths, which are whitish in color ▪ Nerve Tracts / Conduction Pathways – found on the CNS which propagate action potential from one area of the CNS to another ▪ Nerves – bundles of axons located in the PNS Electrical Signals of Nervous System: include the resting membrane potential, action potential, synapse, and reflexes Resting Membrane Potential – is the point of equilibrium at which the tendency for K+ to move down its concentration gradient out of the cells is balanced by the negative charge within the cell, which tends to attract the K+ back into the cell. This is generated by three main factors: 1. a high concentration of K+ immediately inside the cell membrane This document is the property of PHINMA EDUCATION 2 of 10  Anatomy & Physiology – Lecture (Nursing) Module #9 Student Activity Sheet Name: _________________________________________________________________ Class number: _______ Section: ____________ Schedule: ________________________________________ Date: ________________ 2. a higher concentration of Na+ immediately outside the cell membrane 3. greater permeability of the cell membrane to K+ than to Na+ Sodium-Potassium Pump – is required to maintain the greater concentration of Na+ outside the cell membrane and K+ inside; occurs in order to compensate for the constant leakage of ions across the membrane. Two Basic Ion Channels: (See Process figure 8.7, page 197 of the book) 1. Leak Channels – always open; K+ channels are much greater than Na+ channels 2. Gated Channels – closed until opened by specific signals ▪ Chemically Gated: opened by neurotransmitters or other chemicals ▪ Voltage-Gated: opened by a change in membrane potential (See Process figure 8.8, page 198 of book) Action Potential – occurs when charge across the cell membrane is briefly reversed; generated by the gated channels. Gated channels open due to stimulus applied resulting to Na+ channels open very briefly ▼ Movement of Na+ inside the cell (Local Current) ▼ Inside of the cell becomes more positive (Depolarization) ▼ Enough Na+ enters the cell; the local potential reaches the threshold value ▼ All-or-None action potential is started ▼ Voltage-gated Na+ channels open and depolarization continues at a much faster pace ▼ Action potentials continue until a brief reversal of charge takes place (Na+ channels close, K+ channels open) ▼ Outward flow of K+ repolarizes the cell membrane to its resting membrane potential (Repolarization) ▼ Charge on cell membrane briefly becomes more negative than the resting membrane potential (Hyperpolarization) ▼ Sodium-Potassium Pump restored Types of Action Potential Conduction: (See Process figures 8.10 & 8.11, page 200) ▪ Continuous Conduction – occurs in unmyelinated axons; an action potential in one part of a cell membrane stimulates local currents in adjacent parts ▪ Saltatory Conduction – occurs in myelinated axons; an action potential ‘jumps’ from one node of Ranvier to the next along the length of the axon Synapse – a junction where the axon of one neuron interacts with another neuron or with cells of an effector organ; involved the release of neurotransmitter (ex: neuromuscular junction) Three Major Components: 1. Presynaptic Terminal – end of axon; has synaptic vesicles that store neurotransmitters This document is the property of PHINMA EDUCATION 3 of 10  Anatomy & Physiology – Lecture (Nursing) Module #9 Student Activity Sheet Name: _________________________________________________________________ Class number: _______ Section: ____________ Schedule: ________________________________________ Date: ________________ 2. Postsynaptic Membrane – membrane of the dendrite or effector cell 3. Synaptic Cleft – space separating the presynaptic terminal & postsynaptic membrane Action potentials arrive in presynaptic terminal ▼ Voltage-gated Ca2+ channels open & Ca2+ moves into the cell ▼ Influx of Ca2+ releases neurotransmitter by exocytosis ▼ Neurotransmitters diffuse across the synaptic cleft & bind to specific receptor molecules in postsynaptic membrane ▼ Chemically gated channels (Na+, K+, or Cl-) open or close depending on: ✔ type of neurotransmitter (See table 8.2, page 202) ✔ type of receptors ▼ Stimulation or Inhibition of action potential Neurotransmitters: (See table 8.2, page 202) Reflexes – involuntary reactions in response to a stimulus applied to the periphery & transmitted to CNS; allow a person to react to stimuli more quickly; no conscious thought is required. Reflex Arc – the neuronal pathway by which a reflex occurs; basic functional unit of nervous system; smallest, simplest pathway capable of receiving a stimulus & yielding a response. Five Basic Components of Reflex Arc: (See Process figures 8.13, page 203) 1. Sensory Receptor – pick up the stimulus 2. Sensory Neuron – afferent; send stimulus to interneurons in spinal cord 3. Interneurons – located in CNS and connect to motor neurons; process stimulus to some reflexes 4. Motor Neuron – efferent; send response to effector 5. Effector Organ – muscles or glands Neuronal Pathways are divided into two simplest types: (See Process figures 8.14, page 203) ▪ Converging Pathway – two or more neurons synapse with the same postsynaptic neuron; allows transmitted information in more than one neuronal pathway to converge into a single pathway ▪ Diverging Pathway – axon from one neuron divides & synapses with more than one other postsynaptic neuron; allows transmitted information in one neuronal pathway to diverge into two or more pathways Summation – this allows the integration of multiple subthreshold local potentials from the signals in neuronal pathways which can bring the membrane potential to threshold & trigger action potential. ▪ Spatial Summation: occurs when the local potentials originate from different locations on the postsynaptic neuron (ex: from converging pathways) ▪ Temporal Summation: occurs when local action potentials overlap in time; from a single input that fires rapidly, which allows the local potentials to overlap briefly Spinal Cord – extends from the foramen magnum at the base of the skull to the 2nd lumbar vertebra; protected by vertebral column; its inferior end where the spinal nerves exit is called cauda equina (resembles a horse’s tail) This document is the property of PHINMA EDUCATION 4 of 10  Anatomy & Physiology – Lecture (Nursing) Module #9 Student Activity Sheet Name: _________________________________________________________________ Class number: _______ Section: ____________ Schedule: ________________________________________ Date: ________________ Organization of Spinal Cord: (See figure 8.16, page 205) ▪ Gray Matter – mainly collection of cell bodies at the center of spinal cord that is shaped like letter H or butterfly; consists of four structures: o Posterior Horns: contain axons which synapse with interneurons ▪ Dorsal Root Ganglion – contains cell bodies of pseudo-unipolar sensory neurons & axons that originate in the periphery of the body; passes through spinal nerves & dorsal roots of this horn o Anterior Horns: contain somatic neurons o Lateral Horns: contain autonomic neurons o Central Canal: fluid-filled space in the center of the cord ▪ White Matter – located at the superficial portion; each half is organized into three columns: dorsal / posterior, ventral / anterior, and lateral columns. Each column contains two nerve tracts/pathways: o Ascending Tracts: consist of axons that conduct action potentials toward the brain o Descending Tracts: consist of axons that conduct action potentials away from the brain Spinal Cord Reflexes: (See Process figures 8.18 & 8.19, pages 206-207) 1. Knee-Jerk Reflex / Patellar Reflex – a classic example of stretch reflex in which the stimulus is stretching of the quadriceps femoris muscles; done when the patellar ligament is tapped. ✔ Function: Measures the posture maintenance and coordination of muscle activity ✔ if absent or greatly exaggerated, it may indicate that neurons within the brain or spinal cord is damaged 2. Withdrawal Reflex / Flexor Reflex – contains pain receptors as its sensory receptors; if stimulated, reflex occurs ✔ Function: Remove a limb or another body part from a painful stimulus Painful Stimuli to Pain Receptors ► Sensory Neuron ► Dorsal Root ► Interneurons ► Ventral Root ► Motor Neuron of Flexor Muscles ► Withdrawal Spinal Nerves – arise along spinal cord from union of dorsal & ventral roots. (See figure 8.20, page 209) ✔ All contain axons from both sensory and somatic motor neurons (mixed nerves) ✔ Categorized by region of vertebral column from which they emerge – cervical (C1 to C8), thoracic (T1 to T12), lumbar (L1 to L5), sacral (S1 to S5), and coccygeal (Co) – 31 pairs in total ✔ Dermatome - area of skin supplied with sensory innervation by a pair of spinal nerves; each spinal nerves has specific cutaneous sensory distribution (except C1) Plexus – area where neurons of spinal nerves come together & intermingle Major Plexuses of the Spinal Nerves: (See table 8.3, page 209) Brain – consists of its major regions which are the brainstem, the cerebellum, the diencephalon, and the cerebrum. Brainstem – connects the spinal cord to the remainder of brain (See figure 8.22, page 211) Brainstem Location Prominent Features Function Component regulates heart rate, blood vessel inferior portion; Pyramids – two enlargement at uppermost Medulla diameter, breathing, swallowing, continuous with part (anterior); involved in conscious control of Oblongata vomiting, hiccupping, coughing, spinal cord skeletal muscle sneezing, balance This document is the property of PHINMA EDUCATION 5 of 10  Anatomy & Physiology – Lecture (Nursing) Module #9 Student Activity Sheet Name: _________________________________________________________________ Class number: _______ Section: ____________ Schedule: ________________________________________ Date: ________________ serves as functional bridge between superior to Arched Footbridge – anterior surface; aids in cerebrum & cerebellum, breathing, Pons medulla assisting functions of medulla oblongata swallowing, balance, chewing, oblongata salivation Superior Colliculi – 2 mounds; involved in visual reflexes & receive touch & auditory input smallest Inferior Colliculi – major relay centers for region; coordinated eye movements, Midbrain auditory nerve pathways in CNS superior to the controlling pupil diameter, lens shape Substantia Nigra – black nuclear mass that is pons involved in regulating general body movements Reticular Formation – a group of nuclei scattered throughout the brainstem ✔ Function: regulates cyclical motor function (respiration, walking, chewing) ✔ This is a major component of the Reticular Activating System, which plays an important role in arousing and maintaining consciousness, and in regulating sleep-wake cycle Cerebellum – attached to brainstem by several large connections called cerebellar peduncles; known as “little brain” ✔ Structure: Cortex is composed of gray matter, gyri, and sulci; internally contains gray nuclei & white nerve tracts ✔ Functions: Maintaining balance & muscle tone, coordination of fine motor movements, learning motor skills ✔ Comparator – a major function which serves as a sensing device that compares the data from two sources – motor cortex & peripheral structures ✔ Proprioceptive Neurons – innervated in joints, tendons, and muscles that provide information about the position of the body; send action potentials to cerebellum Diencephalon – part of brain between brainstem & cerebrum consisting of: (See figure 8.23, page 212) Component Location Characteristics Function consists of cluster of nuclei shaped like a yo-yo influences moods & detects Thalamus largest part Interthalamic Adhesion – centrally connect the two pain (unlocalized) large, lateral parts consists of few small nuclei small area superior & emotional & visceral Epithalamus Pineal Gland – an endocrine gland that influences posterior to response to odors the onset of puberty & controlling some long-term thalamus cycles that are influenced by the light-dark cycle contains several small nuclei plays a central role in maintaining homeostasis, Infundibulum – a funnel-shaped stalk that extends control of body temperature, most inferior from the floor of hypothalamus to pituitary gland hunger, thirst, sexual Hypothalamus part; below pleasures, rage, fear, thalamus Mammillary Bodies – visible swelling on posterior relaxation after meal, control part of hypothalamus that are involved in emotional the secretion of hormone responses to odors and memory from pituitary gland This document is the property of PHINMA EDUCATION 6 of 10  Anatomy & Physiology – Lecture (Nursing) Module #9 Student Activity Sheet Name: _________________________________________________________________ Class number: _______ Section: ____________ Schedule: ________________________________________ Date: ________________ Cerebrum – largest part of the brain which is divided into right & left hemisphere by longitudinal fissure (See figure 8.24, page 213) Lobes of Cerebral Hemispheres: 1. Frontal Lobe – vital in control of voluntary motor functions, motivation, aggression, mood, & olfactory reception 2. Parietal Lobe – principal center for receiving & consciously perceiving most sensory information such as touch, pain, temperature, and balance 3. Occipital Lobe – functions in receiving and perceiving visual input 4. Temporal Lobe – involved in olfactory & auditory sensations; plays an important role in memory ▪ Psychic Cortex: anterior & inferior portion of temporal lobe associated with abstract thought & judgment 5. Insula / Fifth Lobe – deep within the lateral fissure; it processes interoception – the sensory information on physiologic condition of body (heartbeat & blood pressure regulation & gastric motility) Cerebral Cortex – located at the surface of cerebrum that is composed of gray matter ✔ Functions: controls thinking, communicating, remembering, understanding, & initiates involuntary movements Prominent Features: ▪ Gyri – folds on cerebral cortex that greatly increase the surface area ▪ Sulci – intervening grooves; shallow indentations o Central Sulcus – separates the frontal and parietal lobes ▪ Lateral Fissure – separates most of the temporal lobe from the rest of cerebrum CHECK FOR UNDERSTANDING You will answer and rationalize this by yourself. This will be recorded as your quiz. One (1) point will be given to the correct answer and another one (1) point for the correct ratio. Superimpositions or erasures in your answer/ratio is not allowed. You are given 20 minutes for this activity. 1. Which of the following is not a major function of the nervous system? a. receive motor input c. maintain homeostasis b. integrate information d. control muscles and glands ANSWER: ________ RATIO:______________________________________________________________________________ ____________________________________________________________________________________ __________________________ 2. Leak ion channels: a. open in response to changes in the membrane potential b. are always open c. open in response to neurotransmitters or other chemicals d. are closed until opened by specific signals e. are responsible for the generation of the action potential in neurons ANSWER: ________ RATIO:______________________________________________________________________________ ____________________________________________________________________________________ This document is the property of PHINMA EDUCATION 7 of 10  Anatomy & Physiology – Lecture (Nursing) Module #9 Student Activity Sheet Name: _________________________________________________________________ Class number: _______ Section: ____________ Schedule: ________________________________________ Date: ________________ ____________________________________________________________________________________ _______________________________________ 3. Which of the following is not TRUE of K+ leak channels? a. are always open. b. are 50 - 100 times more prevalent than Na+ leak channels. c. have the greatest contribution to the resting potential of the cell. d. are responsible for the depolarization phase of the action potential. e. allow K+ ions to "leak" down their concentration gradient and out of the cell. ANSWER: ________ RATIO:______________________________________________________________________________ ____________________________________________________________________________________ ____________________________________________________________________________________ _______________________________________ 4. What will happen next after the neurotransmitter activation of chemically gated channels? a. the K+ channels open for a brief time generating a local current b. the cell may reach threshold c. the inside of the membrane becomes more negative d. an action potential is generated ANSWER: ________ RATIO:______________________________________________________________________________ ____________________________________________________________________________________ ____________________________________________________________________________________ _______________________________________ 5. Continuous conduction of the action potential: a. occurs in myelinated axons d. is quicker than saltatory conduction b. occurs primarily in unmyelinated axons e. occurs in myelinated axons & quicker than c. is a function of the nodes of Ranvier saltatory conduction ANSWER: ________ RATIO:______________________________________________________________________________ ____________________________________________________________________________________ ____________________________________________________________________________________ _______________________________________ 6. Which of the following statements about summation in the nervous system is INCORRECT? a. Summation of signals in neuronal pathways allows integration of multiple subthreshold changes in local potential. b. Spatial summation occurs when local potentials originate from different locations on the postsynaptic neuron. c. Spatial summation also occurs when local potentials overlap in time. d. Both spatial & temporal summation can lead to either inhibition or stimulation depending upon the signal type. e. A single presynaptic action potential usually does not cause a sufficiently large postsynaptic local potential to cause the postsynaptic cell to reach threshold. ANSWER: ________ RATIO:______________________________________________________________________________ ____________________________________________________________________________________ This document is the property of PHINMA EDUCATION 8 of 10  Anatomy & Physiology – Lecture (Nursing) Module #9 Student Activity Sheet Name: _________________________________________________________________ Class number: _______ Section: ____________ Schedule: ________________________________________ Date: ________________ ____________________________________________________________________________________ _______________________________________ 7. In a neuron, short, branching cytoplasmic extensions that receive information and carry it to the cell body are called: a. dendrites. c. cell bodies. b. axons. d. myelin sheaths. ANSWER: ________ RATIO:______________________________________________________________________________ ____________________________________________________________________________________ ____________________________________________________________________________________ _______________________________________ 8. Gaps between segments of oligodendrocytes or between individual Schwann cells are called: a. ganglia. d. ependymal cells. b. microglia. e. nerve tracts. c. nodes of Ranvier. ANSWER: ________ RATIO:______________________________________________________________________________ ____________________________________________________________________________________ ____________________________________________________________________________________ _______________________________________ 9. Chemical substances released from the presynaptic terminal: (Select all that apply) a. bind to receptors on the presynaptic terminal. b. may inhibit or stimulate an action potential in the presynaptic terminal depending on the receptors. c. are normally broken down by enzymes located in the synapse. d. are called neurotransmitters. ANSWER: ________ RATIO:______________________________________________________________________________ ____________________________________________________________________________________ ____________________________________________________________________________________ _______________________________________ 10. Pepper, with her partner in Health Assessment, conducts the knee-jerk reflex using a reflex hammer. She taps the patellar ligament of her partner which results in contraction of quadriceps femoris muscles and extension of the leg. As a student, you know that this is associated with the reflex arc. Which of the following is NOT an essential component of a reflex arc? a. sensory receptor d. efferent (motor) neuron b. afferent (sensory) neuron e. effector organ c. spinal pathway ANSWER: ________ RATIO:______________________________________________________________________________ ____________________________________________________________________________________ ____________________________________________________________________________________ _______________________________________ This document is the property of PHINMA EDUCATION 9 of 10  Anatomy & Physiology – Lecture (Nursing) Module #9 Student Activity Sheet Name: _________________________________________________________________ Class number: _______ Section: ____________ Schedule: ________________________________________ Date: ________________ LESSON WRAP-UP AL Activity: CAT: MUDDIEST POINT This technique will help you determine which key points were missed in the main lesson. You will respond to only one question: In today’s session, what was least clear to you? ____________________________________________________________________________________ ____________________________________________________________________________________ ____________________________________________________________________________________ This document is the property of PHINMA EDUCATION 10 of 10