Anatomy & Physiology Notes - Week 2 & 3 - Student Copy Handout (2) PDF

ANATOMY & PHYSIOLOGY Prepared by Camille Nas, PTRP, RPT Prayer before class… Dear Lord and Father of all, Thank you for today. Thank you for ways in which you provide for us all. For Your protectio...

ANATOMY & PHYSIOLOGY Prepared by Camille Nas, PTRP, RPT Prayer before class… Dear Lord and Father of all, Thank you for today. Thank you for ways in which you provide for us all. For Your protection and love we thank you. Help us to focus our hearts and minds now on what we are about to learn. Inspire us by Your Holy Spirit as we listen and write. Guide us by your eternal light as we discover more about the world around us. We ask all this in the name of Jesus. Amen LEARNING OBJECTIVES: Describe the anatomical position, and explain its importance. Discuss homeostasis Use proper anatomical terminology to describe body regions, orientation and Describe a negative-feedback direction, and body planes. mechanism and give an example. Name the body cavities, and indicate the Describe a positive-feedback important organs in each. Name and describe the serous membranes of mechanism and give an example. the ventral body cavities. Identify the abdominopelvic quadrants and regions on a torso model or image. Define the directional terms for the human body and use them to locate specific body structures. lecture website INTRODUCTION TO THE HUMAN BODY  ANATOMY vs PHYSIOLOGY ANATOMY PHYSIOLOGY - Structures of the body - Processes of functions of living things MAJOR GOAL: 1. Understand and predict body’s response to stimuli 2. How body maintains conditions within a range of values during constant changing environment internally and externally Structural and Functional Organization of the Human Body 6 levels of organization of body: 1. Chemical 2. Cell 3. Tissue 4. Organ 5. Organ system 6. Organism  HOMEOSTASIS Existence and maintenance of relatively constant environment in the body despite changes outside continuously dynamic state of equilibrium Affected by variables Changes in internal body conditions Values are not constant Ex. Body temp., volume, chemical content, pH level stimulus A changed variable is called? __________ NORMAL RANGE For cells to function normally Narrow range set point of homeostasis to maintain near normal value  Feedback Loops Regulates homeostasis TYPES: 1.Negative feedback 2.Positive feedback COMPONENTS: 1. Receptor 2. Control center 3. Effector 1. Negative feedback More common in homeostasis “to decrease” or reduce intensity cause the variable to change in a direction opposite to that of the initial change, returning it to its “ideal” value (the set point) 1. Positive feedback Enhances the original stimulus Further response, adds is “positive” because the change that results proceeds in the same direction as the initial change, I. ANATOMICAL POSITION Standing erect Face and feet directed forward Upper limb at the side Palms facing forward II. DIRECTIONAL TERMS Supine vs Prone Superior vs Inferior Anterior vs Posterior Ventral vs Dorsal Proximal vs Distal Medial vs Lateral Superficial vs Deep SUPINE PRONE II. DIRECTIONAL TERMS 1. WHAT VIEW IS THIS SHOWING? A. ANTERIOR B. POSTERIOR C. LATERAL D. MEDIAL 2. THE FRACTURE IS ______ TO THE ELBOW? A. SUPERIOR B. INFERIOR C. LATERAL D. MEDIAL 2. THE FRACTURE IS ______ TO THE SHOULDER? A. PROXIMAL B. DISTAL C. MEDIAL D. LATERAL III. BODY PARTS & REGIONS III.a. Quadrants III.a. Quadrants BODY PLANES & SECTIONS o Sagittal o Transverse o Frontal BODY PLANES & SECTIONS o Sagittal o Transverse o Frontal BODY CAVITIES PLANES AND MOTION PLANE MOTION SAGITTAL FLEXION- EXTENSION FRONTAL ABDUCTION- ADDUCTION TRANSVERSE ROTATION PLANES AND MOTION PLANE MOTION SAGITTAL FLEXION- EXTENSION FRONTAL ABDUCTION- ADDUCTION TRANSVERSE ROTATION  THE NERVOUS TISSUE AND CELL Prepared by Camille Nas, PTRP, RPT Function of the nervous system regulates and coordinates functions of the body required to maintain homeostasis. NEURONS vs NERVE 2 main cell types: 1. Neurons 2. Glial cells NEURONS NERVES - Electrically excitable cells of - A collection of many axons nervous system bundled together outside the brain and spinal cord  GLIAL CELLS NEURONS - Are supportive cells that - Electrically excitable cells of serve many function for nervous system neurons NEURONS AND GLIAL CELLS Functions: 1. Maintain homeostasis 2. Receive sensory input 3. Integrate information 4. Control muscles and glands 5. Establish and maintain mental activity NEURONS (Nerve cells) structural units of the nervous system. E. A. NUCLEUS B. SOMA OR CELL BODY C. AXON TERMINAL BRANCHES D. AXON A. B. E. DENDRITES C. D.  NEURONS STRUCTURE CELL BODY - Aka soma - Protein synthesis - Packages proteins into vesicles - (+) rough Endoplasmic reticulum (ER) - Nissl bodies - Has spherical nucleus surrounded by cytoplasm - The major biosynthetic center and metabolic center of a neuron  NEURONS STRUCTURE DENDRITES - Extensions of cell body - Receive information - Short and highly branched - Generate small electric currents towards the cell body - Dendritic spines - Small extension where axons of other neurons form connections  NEURONS STRUCTURE AXONS - Arises from axon hillock - INITIAL SEGMENT – narrows to form a slender process that is same in diameter for the rest of its length - Generate signals away from the cell body - NERVE FIBER A LONG AXON IS CALLED _________________ The combination of the axon hillock and the initial segment is called the trigger zone  TYPES OF NEURONS: FUNCTIONAL: 1. SENSORY NEURONS 2. MOTOR NEURONS 3. INTERNEURONS STRUCTURAL: 1. Multipolar 2. Bipolar 3. Pseudo-unipolar 4. anaxonic  TYPES OF NEURONS: MULTIPOLAR Have many dendrites and 1 axon BIPOLAR 1 axon 1 dendrite STRUCTURAL: 1. Multipolar 2. Bipolar 3. Pseudo- PSEUDO-UNIPOLAR unipolar start out as bipolar neurons during 4. anaxonic development, but the two processes that extend rom the cell body fuse into a single process ANAXONIC No axons but only has dendrites GLIAL CELLS OF THE CNS four types of CNS glial cells: (1)astrocytes, (2)ependymal cells, (3)microglia, (4) oligodendrocytes.  GLIAL CELLS OF THE CNS Ependymal Astrocytes Microglia Oligodendrocytes Cells help regulate the line the ventricles CNS-specific composition of (cavities) immune cells extracellular of the brain and derived from the form an insulating brain fluid the central canal same embryonic layer around of the spinal cord tissue as other axons. Blood brain barrier form structures immune cells called choroid within the blood. forming the myelin plexuses sheath mobile and phagocytic  GLIAL CELLS OF THE PNS two types of glial cells in the PNS: (1) Schwann cells and (2) satellite cells. SATELLITE CELLS - surround neuron cell bodies in sensory and autonomic ganglia - Provide support and nutrition to the neuron cell bodies - protect neurons from heavy-metal poisons, such as lead and mercury; absorbing them  GLIAL CELLS OF THE PNS two types of glial cells in the PNS: (1) Schwann cells and (2) satellite cells. SCHWANN CELLS form myelin sheaths. However, unlike oligodendrocytes, each Schwann cell forms a portion of the myelin sheath around only one axon MYELIN SHEATH protects and electrically insulates axons increases the transmission speed of nerve Impulses. MYELIN SHEATH GAPS or nodes of Ranvier - occur at regular intervals (about 1 mm apart) along a myelinated axon. Axon collaterals can emerge at these gaps. In myelinated axons, Schwann cells in the PNS or oligodendrocyte extensions in the CNS repeatedly wrap around a segment of an axon to form a series of tightly wrapped membranes rich in phospholipids, with little cytoplasm sandwiched between the membrane layers It gives myelinated axons a white appearance because of the high lipid concentration. The myelin sheath is not a continuous covering of the axon These characteristics help myelinated axons conduct electrical signals more rapidly than unmyelinated axons.  SYNAPSE The point of contact between axon ending and its effector If an axon has been severed, so that it is no longer connected to its neuron cell body, what will be the effect on the distal and proximal portions of the axon?  ACTION POTENTIALS The electrical signals produced by the nervous system are called action potentials The membrane potential - A measure of the electrical properties of the plasma membrane and is due to two major characteristics: 1. Ionic concentration differences across the plasma membrane 2. Permeability characteristics of the plasma membrane Ionic Concentration Differences Across the Plasma Membrane There is a higher concentration of Na+ and Cl− outside the cell than inside the cell, while there is a higher concentration of K+ inside the cell Role of Membrane Ion Channels channels that are selective as to the type of ion (or ions) it allows to pass. TYPES OF ION For example, a potassium ion channel allows only potassium ions to pass CHANNELS: 1. Leakage or nongated channels 2. Chemically gated channels Voltage-gated channels 3. Mechanically gated channels TYPES OF ION CHANNEL: 2. Gated Ion Channels - closed until opened by specific signals 1. Leak Ion Channels - by opening and closing, these - Nongated ion channel channels can change the permeability - always open of the plasma membrane. - are responsible for the permeability of the plasma membrane to ions when the plasma membrane is unstimulated, or at There are three major types of gated ion channels: rest. 1. Ligand-gated ion channels 2. Voltage-gated ion channels 3. Other gated ion channels  Gated Ion Channels 1. Ligand-gated ion channels stimulated to open by the binding of a specific molecule to the receptor site of the ion channel - The specific molecule that binds to the receptor site can be referred to as a ligand. Ligands could be neurotransmitters or hormones,  Gated Ion Channels 1. Voltage-gated ion channels open and close in response to a specific, small voltage change across the plasma membrane In an unstimulated cell, the inside of the cell is negatively charged relative to the outside. When gated ion channels open, ions diffuse quickly across the membrane. The direction an ion moves (into or out of the 1. Concentration gradient cell) is determined by the electrochemical 2. Electrical gradient gradient. The electrochemical gradient has two components: Establishing the MEMBRANE POTENTIAL Resting Membrane Potential - Measured by comparing the charge inside to the outside of the cell there are opposite charges, or poles, across the membrane, the plasma Resting membrane potential membrane is referred to as being - Unstimulated - Resting cell polarized. - By convention, the potential difference is reported as a negative number POTENTIAL DIFFERENCE because the inside of the plasma electrical charge membrane is negative compared with difference across the the outside plasma membrane Changing the Resting Membrane Potential There are two types of changes to the resting membrane potential: (1) depolarization and (2) hyperpolarization. Changing the Resting DEPOLARIZATION Membrane Potential There are two types of changes - Inside of the cell is more positive to the resting membrane - Action potential is generated potential: - The movement of membrane potential closer to zero (1) depolarization and - it is always excitatory to the cell. (2) hyperpolarization. - For example, if the membrane potential increases from −70 mV to −55 mV - Several factors can lead to depolarization of neurons, including (1) Na+ entry, (2) Ca2+ entry, and (3) changes in extracellular K+ concentration.  DEPOLARIZATION: SODIUM IONS - Most common cause of depolarization - Regulated since only few Na leak channels - Stronger entry with ligand-gated r voltage gated - Enters inside cell - As Na+ diffuses into the cell, the inside of the membrane becomes more positive, or is depolarized. - This is the principal way most neurons respond to excitatory stimuli  Ca+ Regulation of Na entry via concentration of: unbinds CALCIUM IONS Ca + - Higher concentration outside;extracellular fluid Ca+ Ca + - Enters when voltage-gated channels open Ca + - Found in some cardiac muscle cells - However, Ca2+ also plays two other significant roles in action potentials: - (1) regulation of voltage-gated Na+ channels and - (2) regulation of neurotransmitter secretion at the presynaptic terminal  CALCIUM IONS Decrease vs Increase Concentration DECREASE CONCENTRATION INCREASE CONCENTRATION Calcium outside cell is attracted to negatively charged groups of proteins binds to voltage-gated Na+ within the voltage-gated Na channels channels, causing them to - If Ca concentration decrease, it diffuses close. away from the voltage-gated Na channels, causing the gate to open - = Voltage-gated Na Channel OPEN  Ca+ Ca+ 2. Ca Ca+Ca+ binds Ca+ Ca+ 1. When Ca concentration is Ca+ HIGH Ca+ extracellularly Ca+ Ca+ 3. CLOSES the gate  Ca+ unbinds 1. When Ca concentration is LOW Ca + IN SUMMARY Extracellularly Ca+ Ca + Ca + + + Ca Ca+ Ca 2. Ca on the receptor site Calcium BINDS = Gate Closed UNBINDS Ca+ No sodium entry 3. GATE OPENS 4. Na enters  WHAT CAUSES HYPERPOLARIZATION? 2 FACTORS: 1. SLOW EXIT OF K+ VIA POTASSIUM LEAK CHANNELS: POTASSIUM IONS diffuses out of the cell - If concentration outside is INCREASES = K+ STAYS INSIDE - Remember, Potassium in normal state is higher in concentration intracellularly - When K+ stays inside, cell is depolarized (positively charged membrane potential) POTASSIUM IONS diffuses out of the cell Resting membrane - If concentration outside is INCREASES = potential K+ STAYS INSIDE - Remember, Potassium in normal state is higher in concentration intracellularly - When K+ stays inside, cell is depolarized (positively charged membrane potential) Changing the Resting Membrane Potential HYPERPOLARIZATION There are two types of changes to the resting membrane potential: - Inside of the cell is more NEGATIVE - For example, if the membrane potential (1) depolarization and decreases from −70 mV to −90 mV, then (2) hyperpolarization. the cell is less likely to generate an action potential. - There are two major ways to hyperpolarize neurons: (1) K+ exit and (2) Cl− entry. 2. ENTRY OF CHLORIDE IONS - NEGATIVELY CHARGED higher concentration outside the cell - Opening of ligand-gated Cl− channels causes Cl− to diffuse into the cell. introduction of the negatively charged Cl− into the cell hyperpolarizes it HYPER POLARIZED = INCREASED NEGATIVE CHARGE INSIDE CELL LET’S RECAP: VOLTAGE-GATED CHANNELS FOR: LIGAND GATED CHANNELS: 1. Sodium ENTRY GATE OF: 1. Chloride - LEAK CHANNELS: 2. Potassium+ 1. Potassium** 2. Sodium Changing the Resting Changes in membrane potential can Membrane Potential produce two types of signals: A change in membrane potential can be produced by: 1. Graded Potentials (1) anything that 2. Action Potentials alters ion concentrations on the two sides of the membrane, or (2) anything that changes membrane permeability to any ion GRADED POTENTIALS ACTION POTENTIALS incoming signals operating over long-distance signals of axons that short distances that have variable always have the same strength (graded) strength GRADED POTENTIALS Short lived Localized changes Usually in dendrites Important because they sum together and determine whether or not an action potential occurs Intensity of voltage decreases with distance Strength varies directly with stimulus strength The stronger the stimulus, the more voltage generated OTHER NAMES: Receptor potential Generator potential Post synaptic potential End-plate potential GRADED POTENTIALS Graded potentials can be either (1) hyperpolarizing or (2) depolarizing. SUMMATION = the combination of graded potentials, which, if sufficiently large, will result in an Hyperpolarizing graded potentials are action potential due to either K+ exit from the cell or Cl− entry into the cell TRESHOLD - a specific membrane potential the membrane potential at which an Depolarizing graded potentials are action potential is generated. always excitatory to the cell An action potential is generated when voltage-gated Na+ channels open depolarizing graded potentials are added together in a process called summation  A brief reversal of membrane potential Change in voltage of about 100mV (from ACTION POTENTIALS -70 to +30mV) Depolarization is followed by Repolarization and a short period of Hyperpolarization whole event is over in a few milliseconds do not decay with distance Only in axons transition from local graded potential to long-distance action potential takes place at the initial segment of the axon. OTHER NAME: Nerve impulse Action potentials have four phases: (1) a depolarization phase, (2) a repolarization phase, (3) an afterpotential, and (4) return to resting membrane potential. All-or-None Voltage-gated K+ Voltage-gated Na+ channel Principle two voltage-sensitive gates: channels: Action potentials occur according to the all-or- 1. activation gates At rest, closed none principle 2. Inactivation gates When stimulus reach a depolarizing At Rest, activation gates are closed threshold Inactivation gates = open Gate opens, BUT more graded potential that SLOWER compared to Na is large enough to Sodium cannot diffuse inside gated channel reach threshold How do membrane potential maintain concentration gradients? SODIUM-POTASSIUM PUMP - ATP driven - First: ejects 3 Na+ Then: transports inside 2 K+ - 3NaOUT 2K+IN 1.D E P O L A R IZ A T IO N T h e re tu rn to R MP , a c tiv a tion T IO N g a te s in th e v o lta g e -g a te d N a + S o d iu m g o e s in s id e th e c e ll c h a n n e ls to c los e a n d th e P o ta s s iu m e x its th e c e ll in a c tiv a tio n g a te s to ope n. o c c u rs b e c a u s e th e v olta g e - g a te d K + c ha nne ls re m a in ope n 2. fo r a s lig h tly lo n g e r tim e th a n it ta k e s to b rin g th e m e m b ra n e R E P O L A R IZ A T I p o te n tia l b a c k to its o rig in a l re s tin g le v e l. ON T h is a llo w s e x tra K + to le a v e th e Ina c tiv a tion N a c ha nne l c los e s , K c e ll, h y p e rp o la riz in g it. c h a n n e l s till ope n = S o d iu m re m a in s o u ts id e P o ta s s iu m s till e x its 4. R MP 3.A F T E R P O T E N T I v o lta g e -g a te d K c h a n n e l c lo s e s R e e s ta b lis h e d b y s o d iu m AL / p o ta s s iu m p u m p H Y P E R P O L A R IZ A  REFRACTORY PERIOD Once an action potential is produced at a given point on the plasma membrane, that area becomes less sensitive to further stimulation 1ST PART: ABSOLUTE REFRACTORY PERIOD from the beginning of the action potential until near the end of repolarization the inactivation gates in the voltage-gated Na+ channels are already open Depolarization ends as the inactivation gates close further depolarization cannot occur 2nd part: RELATIVE REFRACTORY PERIOD Follows the absolute period Very strong stimulus, or a stronger-than-threshold stimulus can initiate another action potential during the relative refractory period the membrane is more permeable to K+ because many voltage-gated K+ channels are open period ends when the voltage-gated K+ channels close and the membrane potential has returned to the resting level ACTION POTENTIAL FREQUENCY Threshold stimulus – produces 1 action potential the number of action potentials produced per unit of time in > just strong enough to reach threshold response to a stimulus is directly proportional to stimulus strength and to the Submaximal stimulus size of the graded potential Includes all threshold and maximal stimulus strength 1. subthreshold action potential frequency increases in 2. submaximal proportion to the strength of the stimulus 3. maximal because the size of the graded potential 4. supramximal increases with stimulus strength SUBTHRESHOLD STIMULUS – any stimulus not MAXIMAL strong enough to produce a graded potential that Produces maximum AP can reach threshold SUPRAMAXIMAL is any stimulus stronger than a maximal stimulus. axon’s ability to produce action potentials is limited, these stimuli cannot produce a greater frequency of action potentials than a nmaximal stimulus. PROPAGATION OF ACTION POTENTIALS: SYNAPSE communication between the cells  CHEMICAL SYNAPSES: ELECTRICAL SYNAPSES: occurs where a chemical messenger, called a neurotransmitter, is used to communicate occur between cells connected by gap a message to an effector junctions are not common in the nervous system but some do exist in other tissues, such as between adjacent cardiac muscle cells CHEMICAL SYNAPSES COMPONENTS: 1. PRESYNAPTIC TERMINAL 2. SYNAPTIC CLEFT 3. POST SYNAPTIC MEMBRANE Neurotransmitters and Neuromodulators Acetylcholine Chatecolamine GABA, glycine, Purines Nueropeptides Gas and lipids (Ach) glutamate - nitrogen- - Short chain such as Nitric Indoleamine (amino acids) containing amino acids oxide and compounds Carbon monoxide - Ex., substance Sometimes P, endorphins referred o as gasotransmitters  Responses at the Postsynaptic Cells: Excitatory and Inhibitory Postsynaptic Potentials IPSP EPSP results from an increase in the permeability of the Occurs because the plasma membrane has become plasma membrane to Cl− or K+, resulting in more permeable to Na+. hyperpolarization of the postsynaptic cell When depolarization of post-synaptic occurs Response is stimulatory the response is inhibitory because no action depolarization might reach threshold potentials are generated producing an action potential and a response from the cell. move the membrane potential farther from threshold, Caused by EXCITATORY NEURONS decreases the likelihood of an action potential being generated.  SPATIAL AND TEMPORAL SUMMATION: SPATIAL TEMPORAL Multiple APs from separate neurons arrive When 2 or more Aps arrive very close simultaneously at the same post synaptic together at post-synaptic neuron The 1st AP cause depolarizing graded each action potential causes a depolarizing potential that remains few milliseconds graded potential that undergoes summation at before disappear the trigger zone. in the postsynaptic cell results when the If the summated depolarization reaches second action potential from the threshold, an action potential is produced presynaptic neuron initiates a second graded depolarization before the postsynaptic cell’s membrane potential returns to its resting value APs have “tempo” in depolarizing a cell Neuronal Pathways and Circuits four basic patterns of parallel pathways can be recognized: (1) Convergent pathways, (2) divergent pathways, (3) reverberating circuits, and (4) parallel after-discharge circuits. DIVISIONS OF THE NERVOUS SYSTEM: 1. CENTRAL NERVOUS SYSTEM 2. PERIPHERAL NERVOUS SYSTEM End of lecture. Prepare for post-lecture quiz. 1ST POST QUIZ = 15 ITEMS 2ND POST QUIZ = 25 ITEMS