Nerve Tissue & Nervous System PDF

NERVE TISSUE & THE NERVOUS SYSTEMPART 1 OF 3 PAULYN V. ILARINA-ZONITA, MD, DPSP OUTLINE DEVELOPMENT OF NERVE TISSUE NEURONS GLIAL CELLS AND NEURONAL ACTIVITY HUMAN NERVOUS SYSTEM the most complex system in the body formed by a network of many billion nerve cells (neurons) assiste...

NERVE TISSUE & THE NERVOUS SYSTEMPART 1 OF 3 PAULYN V. ILARINA-ZONITA, MD, DPSP OUTLINE DEVELOPMENT OF NERVE TISSUE NEURONS GLIAL CELLS AND NEURONAL ACTIVITY HUMAN NERVOUS SYSTEM the most complex system in the body formed by a network of many billion nerve cells (neurons) assisted by many more supporting cells called glial cells 2 MAJOR ANATOMIC DIVISIONS OF THE NERVOUS SYSTEM Central nervous system (CNS) brain and spinal cord Peripheral nervous system (PNS) cranial, spinal, and peripheral nerves conducting impulses to and from the CNS and ganglia that are small aggregates of nerve cells outside the CNS 2 MAJOR FUNCTIONAL DIVISIONS OF THE NERVOUS SYSTEM Sensory division (afferent) Somatic Visceral Motor division (efferent) Somatic Autonomic TWO KINDS OF CELLS OF THE NERVOUS TISSUE NEURONS o typically have numerous long processes o respond to environmental changes (stimuli) GLIAL CELLS o have short processes; support and protect neurons, and participate in many neural activities, neural nutrition, and defense of cells in the CNS DEVELOPMENT OF NERVE TISSUE  CNS NEURAL NEURAL PNS PLATE TUBE NEURAL ECTODERM CREST OTHER NON- EPIDERMIS NEURONAL CELLS NEURONS Three main parts of a Neuron 1 Cell body/perikaryon/soma 2 Dendrites 3 Axon  CLASSIFICATION OF NEURONS (ACCORDING TO THE NUMBER OF PROCESSES EXTENDING FROM THE CELL BODY) Multipolar Bipolar neurons neurons Unipolar/ Anaxonic pseudounipolar neurons neurons FUNCTIONAL DIVISION OF THE NERVOUS TISSUE Sensory neurons Motor neurons receiving stimuli sending impulses Somatic motor nerves autonomic motor nerves voluntary control involuntary or unconscious activities CELL BODY (PERIKARYON OR SOMA) contains the nucleus and surrounding cytoplasm acts as a trophic center, producing most cytoplasm for the processes conveying excitatory or inhibitory stimuli has an unusually large, euchromatic nucleus with a prominent nucleolus DENDRITES short, small processes emerging and branching off the soma the principal signal reception and processing sites on neurons  Unlike axons, which maintain a nearly constant diameter, dendrites become much thinner as they branch most synapses on dendrites occur on dendritic spines- dynamic membrane protrusions along the small dendritic branches; serve as the initial processing sites for synaptic signals  Changes in dendritic spines are of key importance in the constant changes of the neural plasticity that occurs during embryonic brain development and underlies adaptation, learning, and memory postnatally. AXONS Most neurons have only one axon, typically longer than its dendrites Axonal processes vary in length and diameter according to the type of neuron (Axons of the motor neurons that innervate the foot muscles have lengths of nearly a meter) The plasma membrane of the axon is often called the axolemma and its contents are known as axoplasm.  Axoplasm contains mitochondria, microtubules, neurofilaments, and transport vesicles, but very few polyribosomes or cisternae of RER---- features that emphasize the dependence of axoplasm on the perikaryon. If an axon is severed from its cell body, its distal part quickly degenerates and undergoes phagocytosis. NERVE IMPULSES/ACTION POTENTIAL an electrochemical process initiated at the axon hillock when other impulses received at the cell body or dendrites meet a certain threshold travels along an axon  The action potential is propagated along the axon as a wave of membrane depolarization produced by voltage-gated Na+ and K+ channels in the axolemma that allow diffusion of these ions into and out of the axoplasm. SYNAPSES sites where nerve impulses are transmitted from one neuron to another unidirectional convert an electrical signal (nerve impulse) from the presynaptic cell into a chemical signal that affects the postsynaptic cell release neurotransmitters EXCITATORY OR INHIBITORY SYNAPSES Neurotransmitters from excitatory synapses cause postsynaptic Na+ channels to open, and the resulting Na+ influx initiates a depolarization wave in the postsynaptic neuron or effector cell. At inhibitory synapses neurotransmitters open Cl– or other anion channels, causing influx of anions and hyperpolarization of the postsynaptic cell, making its membrane potential more negative and more resistant to depolarization. CATEGORIES OF NEUROTRANSMITTERS Certain amino acids (glutamate and GABA) Monoamines (serotonin and catecholamines) Small polypeptides (endorphins and substance P)  After their release, transmitters are removed by enzymatic breakdown, by glial activity, or by endocytotic recycling involving presynaptic membrane receptors. Table 9–1  GLIAL CELLS AND NEURONAL ACTIVITY GLIAL CELLS support neuronal survival and activities 10 times more abundant than neurons develop from progenitor cells of the embryonic neural plate support neurons and creating immediately around those cells microenvironments that are optimal for neuronal activity NEUROPIL network of fine cellular processes emerging from neurons and glial cells fibrous intercellular network of CNS tissue superficially resembles collagen by light microscopy 1 Oligodendrocyte 4 Microglia 2 Astrocyte 5 Schwann cell 3 Ependymal cell 6 Satellite cells of ganglia *Table 9–2 OLIGODENDROCYTES predominant glial cells in white matter usually appear as small cells with rounded, condensed nuclei and unstained cytoplasm ASTROCYTES large number of long radiating, branching processes glial fibrillary acid protein (GFAP)- unique marker by far the most numerous glial cells of the brain, as well as the most diverse structurally and functionally Fibrous astrocytes long delicate processes abundant in white matter Protoplasmic astrocyte many shorter processes predominate in the gray matter EPENDYMAL CELLS columnar or cuboidal cells that line the fluid-filled ventricles of the brain and the central canal of the spinal cord cilia: facilitate the movement of CSF microvilli: involved in absorption MICROGLIA small cells with actively mobile processes evenly distributed throughout gray and white matter constitute the major mechanism of immune defense in the CNS originate from circulating blood monocytes SCHWANN CELLS/NEUROLEMMOCYTES found only in the PNS and differentiate from precursors in the neural crest counterparts to oligodendrocytes of the CNS SATELLITE CELLS OF GANGLIA form a thin, intimate glial layer around each large neuronal cell body in the ganglia of the PNS exert a supportive effect on neurons, insulating, nourishing, and regulating their microenvironments  MEDICAL APPLICATION PARKINSON DISEASE slowly progressing disorder affecting muscular activity characterized by tremors, reduced activity of the facial muscles, loss of balance, and postural stiffness caused by gradual loss by apoptosis of dopamine producing neurons whose cell bodies lie within the nuclei of the CNS substantia nigra treated with l-dopa (l-3,4-dihydroxyphenylalanine) LOCAL ANESTHETICS bind to the voltage-gated sodium channels of the axolemma interfering with sodium ion influx inhibiting the action potential responsible for the nerve impulse  TREATMENT OF DEPRESSION AND ANXIETY DISORDERS Selective serotonin reuptake inhibitors (SSRIs)  MENINGES BLOOD-BRAIN BARRIER CHOROID PLEXUS MEDICAL APPLICATION POST TEST  CEREBRUM CNS CEREBELLUM SPINAL CORD  completely covered by connective tissue layers- the meninges STRUCTURAL FEATURES OF CNS TISSUES differential distribution of lipid-rich myelin: Øwhite matter- composed mainly of myelinated axons (tracts) and oligodendrocytes (myelin-producing) Øfound in deeper regions of the brain Øgray matter- neuronal cell bodies, dendrites, astrocytes, and microglial cells; most synapses occur Ømakes up the thick cortex or surface layer of both the cerebrum and the cerebellum CEREBRAL CORTEX madeup of six layers of neurons CEREBELLAR CORTEX coordinates muscular activity throughout the body organized with three layers 1. Molecular layer: thick, outer layer has much neuropil and scattered neuronal cell bodies 2. Purkinje cells: thin, middle layer consists only of very large neurons 3. Granular layer: thick, inner layer contains various very small, densely packed neurons and little neuropil SPINAL CORD white matter: peripheral layer gray matter: deeper, H-shaped layer anterior horns: motor posterior horns: sensory  sensory motor gray matter white matter LAYERS OF THE MENINGES Dura Mater Arachnoid Pia mater DURA MATER “tough mother” thick external consists of dense irregular connective tissue outer periosteal layer inner meningeal layer ARACHNOID “spider web-like” two components: sheet of connective tissue in contact with the dura mater system of loosely arranged trabeculae composed of collagen and fibroblasts, continuous with the underlying pia mater layer Subarachnoid space- surrounds the trabeculae; large, spomge-like cavity, filled with CSF; helps cushion and protect the CNS from minor trauma  The connective tissue of the arachnoid is avascular Thearachnoid and the pia mater are intimately associated and are often considered a single membrane called the pia- arachnoid PIA MATER “tender mother” innermost layer consists of flattened, mesenchymally derived cells separated from the neural elements by the very thin superficial layer of astrocytic processes (the glial limiting membrane, or glia limitans)- physical barrier separating CNS tissue from CSF in the subarachnoid space BLOOD-BRAIN BARRIER (BBB) functional barrier capillary endothelium: main structural component cells are tightly sealed together with well-developed occluding junctions little or no transcytosis activity surrounded by the basement membrane + limiting layer of perivascular astrocytic feet  protects neurons and glia from bacterial toxins, infectious agents, and other exogenous substances helps maintain the stable composition and constant balance of ions  hypothalamus posterior pituitary choroid plexus CHOROID PLEXUS highly vascular tissue found in the roofs of the third and fourth ventricles Each villus of the choroid plexus contains a thin layer of well-vascularized pia mater covered by cuboidal ependymal cells FUNCTION OF THE CHOROID PLEXUS Remove water from blood and release it as the CSF CEREBROSPINAL FLUID clear fluid; contains Na+, K+, and Cl– ions but very little protein, and sparse lymphocytes. produced continuously and it completely fills the ventricles, the central canal of the spinal cord, the subarachnoid and perivascular spaces help absorb mechanical shocks HYDROCEPHALUS decrease in the absorption of CSF or a blockage of outflow progressive enlargement of the head mental impairment  PERIPHERAL NERVOUS SYSTEM NERVE FIBERS NERVE ORGANIZATION GANGLIA NEURAL PLASTICITY & REGENERATION MEDICAL APPLICATION PERIPHERAL NERVOUS SYSTEM THE MAIN COMPONENTS OF THE PNS NERVES GANGLIA NERVE ENDINGS NERVE FIBERS PERIPHERAL NERVES bundles of nerve fibers (axons) individually surrounded by Schwann cells and connective tissue analogous to tracts in the CNS MYELINATED FIBERS engulfed by a series of differentiating Schwann cells the multiple layers of Schwann cell membrane unite as a thick myelin sheath. Myelin: large lipoprotein complex UNMYELINATED FIBERS even the smallest diameter axons of peripheral nerves are still enveloped within simple folds of Schwann cells- do not however undergo multiple wrapping to form a myelin sheath NERVE ORGANIZATION  Inthe PNS, nerve fibers are grouped into bundles to form nerves nerveshave a whitish, glistening appearance because of their myelin and collagen content  Endoneurium: thin layer immediately around the external lamina of the Schwann cells; consisting of reticular fibers, scattered fibroblasts, and capillaries Perineurium: holds together groups of axons with Schwann cells and endoneurium called the fascicles  Epineurium: dense, irregular fibrous coat which extends deeply to fill the space between fascicles BLOOD-NERVE BARRIER unique connective tissue cells that regulate diffusion into the fascicle helps maintain the fibers’ microenvironment  Peripheral nerves establish communication between centers in the CNS and the sense organs and effectors. They generally contain both afferent and efferent fibers. sensory nerves motor nerves mixed nerves GANGLIA  ovoid structures containing neuronal cell bodies and their surrounding glial satellite cells supported by delicate connective tissue and surrounded by a denser capsule serve as relay stations to transmit nerve impulses- one nerve enters and another exits from each ganglion SENSORY GANGLIA receive afferent impulses that go to the CNS associated with cranial nerves (cranial ganglia)and the dorsal roots of the spinal nerves (spinal ganglia) supported by a distinct connective tissue capsule pseudounipolar AUTONOMIC GANGLIA effect the activity of smooth muscle, the secretion of some glands, heart rate, and many other involuntary activities walls of the digestive tract- intramural ganglia poorly defined capsule multipolar neurons NEURAL PLASTICITY & REGENERATION  neuronal differentiation and formation of new synapses neurons which do not establish correct synapses with other neurons are eliminated by apoptosis reorganized by the growth of neuronal processes, forming new synapses to replace ones lost by injury- functional recovery  Neuronal stem cells are present in the adult CNS subject of intense investigation  In the peripheral nerves, injured axons have a much greater potential for regeneration and return of function  Theonset of regeneration is signaled by changes in the perikaryon that characterize the process of chromatolysis: the cell body swells slightly the Nissl substance is initially diminished thenucleus migrates to a peripheral position within the perikaryon MEDICAL APPLICATION NEUROMA THANK YOU MUSCLE TISSUE PART 1 OF 2 PAULYN V. ILARINA-ZONITA, MD, DPSP OUTLINE SKELETAL MUSCLE Organization of a Skeletal Muscle Organization Within Muscle Fibers Sarcoplasmic Reticulum & Transverse Tubule System Mechanism of Contraction Innervation Muscle Spindles & Tendon Organs Skeletal Muscle Fiber Types MUSCLE TISSUE composed of cells that optimize the universal cell property of contractility actin microfilaments and associated proteins generate the forces necessary for the muscle contraction mesodermal origin Three types of muscle tissue 1 Skeletal muscle 2 Cardiac muscle 3 Smooth muscle Skeletal muscle Cardiac muscle Smooth muscle bundles of very long, elongated, often multinucleated cells branched cells bound fusiform cells with cross- to one another at which lack striations structures called striations intercalated discs Contraction is quick, Contraction is slow forceful, and Contraction is and involuntary usually under involuntary, vigorous, voluntary control. and rhythmic  Contraction is caused by the sliding interaction of thick myosin filaments along thin actin filaments. Skeletal (or striated) muscle consists of muscle fibers, which are long, cylindrical multinucleated cells Elongated nuclei are found peripherally just under the sarcolemma, a characteristic nuclear location unique to skeletal muscle fibers/cells A small population of reserve progenitor cells called muscle satellite cells remains adjacent to most fibers of differentiated skeletal muscle. Organization of a Skeletal Muscle 3 LAYERS OF THE MUSCLE TISSUE 1 Epimysium 2 Perimysium 3 Endomysium EPIMYSIUM PERIMYSIUM ENDOMYSIUM external sheath thin connective of dense tissue layer that very thin, irregular immediately delicate layer of connective surrounds each reticular fibers tissue; bundle of muscle and scattered surrounds the fibers termed a fibroblasts entire muscle fascicle Organization Within Muscle Fibers  Longitudinally sectioned skeletal muscle fibers show striations of alternating light and dark bands dark bands are called A bands (anisotropic or birefringent in polarized light microscopy) light bands are called I bands (isotropic, do not alter polarized light)  The A and I banding pattern in sarcomeres is due mainly to the regular arrangement of thick and thin myofilaments, composed of myosin and F-actin, respectively. MYOSIN ACTIN large complex with two run between the thick identical heavy chains filaments; each G-actin (tail) and two pairs of monomer contains a light chains (head) binding site for myosin Regulatory proteins found in the thin filaments 1 Tropomyosin 2 Troponin  I bands consist of the portions of the thin filaments which do not overlap the thick filaments in the A bands Actin filaments are anchored perpendicularly on the Z disc by the actin- binding protein α-actinin and exhibit opposite polarity on each side of this disc  Titin: supports the thick myofilaments and connects them to the Z disc Nebulin: binds each thin myofilament laterally, helps anchor them to α- actinin, and specifies the length of the actin polymers during myogenesis.  A bands contain both the thick filaments and the overlapping portions of thin filaments H zone: lighter zone seen in the A band; rodlike portions of the myosin molecule and no thin filaments Bisecting the H zone is the M line- containing a myosin-binding protein myomesin Sarcoplasmic Reticulum & Transverse Tubule System Sarcoplasmic Reticulum membranous smooth ER contains pumps and other proteins for Ca2+ sequestration and surrounds the myofibrils Mechanism of Contraction  Contraction occurs as the overlapping thin and thick filaments of each sarcomere slide past one another. neither the thick nor the thin filaments change their length Innervation  An axon from a single motor neuron can form MEPs with one or many muscle fibers. Innervation of single muscle fibers by single motor neurons provides precise control of muscle activity (ex. extraocular muscles) Larger muscles with coarser movements have motor axons that typically branch profusely and innervate 100 or more muscle fibers.  Individual striated muscle fibers do not show graded contraction—they contract either all the way or not at all. To vary the force of contraction, the fibers within a muscle fascicle do not all contract at the same time. Muscle Spindles & Tendon Organs  Striated muscles and myotendinous junctions contain sensory receptors acting as proprioceptors, providing the central nervous system (CNS) with data from the musculoskeletal system. Among the muscle fascicles are stretch detectors known as muscle spindles. Muscle spindle encapsulated by modified perimysium, with concentric layers of flattened cells, containing interstitial fluid and a few thin muscle fibers filled with nuclei and called intrafusal fibers Several sensory nerve axons penetrate each muscle spindle and wrap around individual intrafusal fibers. Changes in length (distension) of the surrounding (extrafusal) muscle fibers caused by body movements are detected by the muscle spindles and the sensory nerves relay this information to the spinal cord. Skeletal Muscle Fiber Types  Skeletal muscles such as those that move the eyes and eyelids need to contract rapidly, while others such as those for bodily posture must maintain tension for longer periods while resisting fatigue. varied expression in muscle fibers of contractile or regulatory protein isoforms and other factors affecting oxygen delivery and use. Basis for identification of types of skeletal musclce fibers: 1. maximal rate of contraction (fast or slow fibers) 2. major pathway for ATP synthesis (oxidative phosphorylation or glycolysis) THREE MAJOR TYPES OF SKELETAL MUSCLE FIBERS 1 Slow oxidative muscle fibers 2 Fast glycolytic fibers 3 Fast oxidative-glycolytic fibers Slow oxidative muscle fibers Fast glycolytic fibers Fast oxidative-glycolytic fibers rapid, short- slow contractions term over long periods intermediate contraction- without fatigue between those of rapid fatique the other two appear dark or types appear white in red in color color MEDICAL APPLICATION Myasthenia gravis autoimmune disorder antibodies against proteins of acetylcholine receptors skeletal muscle weakness Duchenne muscular dystrophy mutations of the dystrophin gene can lead to defective linkages between the cytoskeleton and the extracellular matrix (ECM). Muscle contractions can disrupt these weak linkages, causing the atrophy of muscle fibers THANK YOU MUSCLE TISSUE PART 2 OF 2 PAULYN V. ILARINA-ZONITA, MD, DPSP OUTLINE CARDIAC MUSCLE SMOOTH MUSCLE REGENERATION OF MUSCLE TISSUE MEDICAL APPLICATION POST TEST CARDIAC MUSCLE  Mesenchymal cells→ chainlike arrays- form complex junctions between interdigitating processes Cells within one fiber often branch and join with cells in adjacent fibers→ tightly knit bundles of cells, interwoven in spiraling layers (characteristic wave of contraction that resembles wringing out of the heart ventricles)  striated banding pattern each cardiac muscle cell usually has only one nucleus and is centrally located, unlike skeletal muscle  A unique characteristic of cardiac muscle is the presence of transverse lines that cross the fibers at irregular intervals where the myocardial cells join - represent the interfaces between adjacent cells and consist of many junctional complexes composed of many desmosomes and fascia adherens junctions, which together provide strong intercellular adhesion during the cells’ constant contractile activity.  The structure and function of the contractile apparatus in cardiac muscle cells are essentially the same as in skeletal muscle Mitochondria occupy up to 40% of the cell volume Fatty acids, the major fuel of the heart, are stored as triglycerides in small lipid droplets.  Ventricles Atria Muscle thicker thinner T-tubules well- smaller or developed, entirely with large absent lumens  Sarcoplasmic reticulum is less well- organized dyads rather than triads  Cardiac muscle fiber contraction is intrinsic and spontaneous Impulses for the rhythmic contraction (or heartbeat) are initiated, regulated, and coordinated locally by nodes of unique myocardial fibers specialized for impulse generation and conduction contraction of individual myocardial fibers is all- or-none SMOOTH MUSCLE  slow and steady contraction blood vessels, digestive, respiratory, urinary, and reproductive tracts elongated, tapering, and unstriated cells  single, elongated, centrally located nucleus All cells are linked by numerous gap junctions. Concentrated near the nucleus are mitochondria, polyribosomes, RER, and vesicles of a Golgi apparatus.  The fibers have rudimentary sarcoplasmic reticulum, but lack T-tubules bundles of thin and thick myofilaments crisscross the sarcoplasm obliquely actin filaments are not associated with troponin and tropomyosin, using instead calmodulin and Ca2+-sensitive myosin light-chain kinase (MLCK) to produce contraction Structures unique to smooth muscles: dense bodies intermediate filaments (desmin)  not under voluntary motor control and its fibers typically lack well-defined neuromuscular junctions Contraction is most commonly stimulated by autonomic nerves; GIT- paracrine secretions; uterus by oxytocin. stimulation is propagated to more distant fibers via gap junctions that allow all the smooth muscle cells to contract synchronously or in a coordinated manner.  smooth muscle cells also supplement fibroblast activity, synthesizing collagen, elastin, and proteoglycans- may reflect less specialization for strong contractions REGENERATION OF MUSCLE TISSUE Skeletal Muscle Mesenchymal satellite cells Cardiac muscle proliferating fibroblasts and growth of connective tissue→ myocardial scars. Smooth muscle capable of a more active regenerative response undergo mitosis and replace the damaged tissue. MEDICAL APPLICATION Myocardial Ischemia lack of oxygen little potential to regenerate after injury on going research: potential of mesenchymal stem cells to form new, site-specific muscle Leiomyomas Benign tumors commonly develop from smooth muscle fibers frequently occur in the wall of the uterus THANK YOU BLOOD PAULYN V. ILARINA-ZONITA, MD, DPSP  OUTLINE I. COMPOSITION OF PLASMA II. BLOOD CELLS Erythrocytes Leukocytes Platelets III. MEDICAL APPLICATION 3/1/20XX SAMPLE FOOTER TEXT 2  § specializedconnective tissue consisting of cells and fluid extracellular material called plasma § about 5 L of blood moves unidirectionally § Formed elements: erythrocytes, leukocytes, platelets 3/1/20XX SAMPLE FOOTER TEXT 3  Blood leaving the circulatory system Clot formed elements and serum 3/1/20XX SAMPLE FOOTER TEXT 4  § clottingis prevented by the addition of anticoagulants § separated by centrifugation into layers that reflect its heterogeneity 3/1/20XX SAMPLE FOOTER TEXT 5 Erythrocytes Plasma Buffy coat hematocrit straw-colored, thin gray-white sedimented translucent, layer material slightly viscous consists of ~44% of the total supernatant leukocytes and blood volume ~55% at the top platelets half ~1% of the volume 3/1/20XX SAMPLE FOOTER TEXT 6 3/1/20XX SAMPLE FOOTER TEXT 7  § Blood is a distributing vehicle, transporting O2 , CO2 , metabolites, hormones, and other substances to cells throughout the body. § Blood also participates in heat distribution, the regulation of body temperature, and the maintenance of acid-base and osmotic balance. 3/1/20XX SAMPLE FOOTER TEXT 8  § Most O2 is bound to hemoglobin in erythrocytes. § Leukocytes have diverse functions and are one of the body’s chief defenses against infection. 3/1/20XX SAMPLE FOOTER TEXT 9 COMPOSITION OF PLASMA Plasma § aqueous solution § pH of 7.4 § composed mostly of plasma proteins, but they also include nutrients, respiratory gases, nitrogenous waste products, hormones, and inorganic ions collectively called electrolytes § The composition of plasma is usually an indicator of the mean composition of the extracellular fluids in tissues. The major plasma proteins include the following: Albumin Globulins Immunoglobulins Complement Fibrinogen proteins 3/1/20XX SAMPLE FOOTER TEXT 12 BLOOD CELLS ERYTHROCYTES § Erythrocytes are terminally differentiated structures lacking nuclei and completely filled with the O2 -carrying protein hemoglobin. § RBCs are the only blood cells whose function does not require them to leave the vasculature.  § flexible biconcave discs § present in most tissue sections § can be used as internal standard to estimate the size of other nearby cells or structures 3/1/20XX SAMPLE FOOTER TEXT 16 3/1/20XX SAMPLE FOOTER TEXT 17 Erythrocyte Plasmalemma § 50% protein: basis for the ABO blood typing system (specifically glycophorin A) § 40% lipid § 10% carbohydrate 3/1/20XX SAMPLE FOOTER TEXT 18 Erythrocyte Cytoplasm § lacks all organelles but is densely filled with hemoglobin § hemoglobin+O2= oxyhemoglobin § hemoglobin+CO2= carbaminohemoglobin 3/1/20XX SAMPLE FOOTER TEXT 19  § Erythrocytes undergo terminal differentiation: § loss of the nucleus and organelles § Lacking mitochondria, they rely on anaerobic glycolysis. § Lacking nuclei, they cannot replace defective proteins. 3/1/20XX SAMPLE FOOTER TEXT 20  § life span: 120 days § Senescent or worn-out RBCs: removed from circulation, mainly by macrophages 3/1/20XX SAMPLE FOOTER TEXT 21 BLOOD CELLS LEUKOCYTES Leukocytes § sphericalin blood plasma; amoeboid and motile after leaving the blood vessels and invading the tissues Two major groups of Leukocyte 01 Granulocytes 02 Agranulocytes cytoplasmic granules: lysosomes lysosomes only and specific granules nucleus: spherical or indented polymorphic nuclei but not lobulated neutrophils, eosinophils, and lymphocytes and monocytes basophils also terminally differentiated cells: depend on glycolysis undergo apoptosis 3/1/20XX SAMPLE FOOTER TEXT 24 3/1/20XX SAMPLE FOOTER TEXT 25  § All leukocytes are key players in the constant defense against invading microorganisms and in the repair of injured tissues § Diapedesis: migration of leukocytes towardss site of injury/invasion § Chemotaxis: attraction of neutrophils to bacteria; rapid accumulation 3/1/20XX SAMPLE FOOTER TEXT 26 Neutrophils (Polymorphonuclear Leukocytes) § 50%-70% of circulating leukocytes, including immature forms § two to five lobes nuclei § usually the first leukocytes to arrive at sites of infection § chemotaxis and phagocytosis 3/1/20XX SAMPLE FOOTER TEXT 27 Cytoplasmic granules 1. Azurophilic primary granules or lysosomes § major role: killing and degrading engulfed microorganisms § contain myeloperoxidase, lysozyme, and defensins 3/1/20XX SAMPLE FOOTER TEXT 28 § 2. Specific secondary granules § have diverse function: secretion of various ECM-degrading enzymes, delivery of additional bactericidal proteins to phagolysosomes, and insertion of new cell membrane components 3/1/20XX SAMPLE FOOTER TEXT 29 Neutrophils § hasthe ability to survive in an anaerobic environment § short-lived cells: § half-life:6-8 hours in blood § life span: 1-4 days in connective tissues 3/1/20XX SAMPLE FOOTER TEXT 30 3/1/20XX 31 Eosinophils § 1%-4% of leukocytes § bilobed nucleus § abundant large, acidophilic specific granules typically staining pink or red § oval with flattened crystalloid cores, ultrastructurally, containing major basic proteins (MBP), an arginine- rich factor and constitutes up to 50% of the total granule protein 3/1/20XX SAMPLE FOOTER TEXT 32  § MBPs, along with eosinophilic peroxidase, other enzymes and toxins, act to kill parasitic worms or helminths § eosinophilsrelease chemokines, cytokines, and lipid mediators, with an important role in the inflammatory response triggered by allergies 3/1/20XX SAMPLE FOOTER TEXT 33 3/1/20XX SAMPLE FOOTER TEXT 34 Basophils § less than 1% of circulating leukocytes § nuclei: two irregular lobes, but the large specific granules overlying the nucleus usually obscure its shape § basophilia of the granules is due to the presence of heparin and other sulfated GAGs § Basophilic-specific granules also contain much histamine and various other mediators of inflammation 3/1/20XX SAMPLE FOOTER TEXT 35 3/1/20XX SAMPLE FOOTER TEXT 36 Lymphocytes § most numerous type of agranulocyte in normal blood smears; approximately one-third of the total leukocytes § spherical nuclei § smallest leukocytes 3/1/20XX SAMPLE FOOTER TEXT 37 “Cluster of Differentiation” B T Lymphocytes NK Cells Lymphocytes Helper (CD4) Cytotoxic (CD8) 3/1/20XX SAMPLE FOOTER TEXT 38  § wider range of sizes than most leukocytes (small, medium, large) § Small lymphocytes are characterized by spherical nuclei with highly condensed chromatin and only a thin surrounding rim of scant cytoplasm § Large lymphocytes have larger, slightly indented nuclei and more cytoplasm that is slightly basophilic 3/1/20XX SAMPLE FOOTER TEXT 39 3/1/20XX SAMPLE FOOTER TEXT 40 Monocytes § precursor cells of macrophages, osteoclasts, microglia, and other cells of the mononuclear phagocyte system § nuclei: large and usually distinctly indented or C- shaped; less condensed chromatin § All monocyte-derived cells are antigen-presenting cells with important roles in immune defense and tissue repair 3/1/20XX SAMPLE FOOTER TEXT 41  § cytoplasm of the monocyte is basophilic and contains many small lysosomal azurophilic granules- bluishgray 3/1/20XX SAMPLE FOOTER TEXT 42 3/1/20XX SAMPLE FOOTER TEXT 43 BLOOD CELLS PLATELETS Blood platelets (or Thrombocytes) § very small non-nucleated, membrane-bound cell fragments § separationfrom the ends of cytoplasmic processes extending from giant polyploid bone marrow cells called megakaryocytes  § Plateletspromote blood clotting and help repair minor tears or leaks in the walls of small blood vessels § Normalplatelet count: 150,000 to 400,000/μL (mm3 ) of blood. § Circulating platelets have a life span of about 10 days. 3/1/20XX SAMPLE FOOTER TEXT 46  § often appear in clumps § discoid,with a very lightly stained peripheral zone, the hyalomere, and a darker-staining central zone rich in granules, called the granulomere. 3/1/20XX SAMPLE FOOTER TEXT 47 Primary aggregation formation of platelet plug Secondary aggregation increase the size of the platelet plug Blood coagulation blood clot or thrombus formation Clot retraction by the action of platelet- derived actin and myosin Clot removal by the action of plasmin 3/1/20XX SAMPLE FOOTER TEXT 48 3/1/20XX SAMPLE FOOTER TEXT 49 MEDICAL APPLICATION § concentration of erythrocytes below the normal range § symptoms: lethargy, shortness of breath, fatigue, skin pallor, and heart palpitations § Erythrocytosis or polycythemia: increased concentration of erythrocytes in blood  § increase in the number of eosinophils in blood § associatedwith allergic reactions and helminthic infections 3/1/20XX SAMPLE FOOTER TEXT 52  § anaphylaxis or anaphylactic shock § type 1 hypersensitivity 3/1/20XX SAMPLE FOOTER TEXT 53  § lymphomas 3/1/20XX SAMPLE FOOTER TEXT 54  § inflammation 3/1/20XX SAMPLE FOOTER TEXT 55  § bleeding disorders 3/1/20XX SAMPLE FOOTER TEXT 56 THANK YOU