Basic Tissues PDF

Topic 1: BASIC TISSUES Assoc. Prof. Dr. Siti Noor Adnalizawati bt Adnan Faculty of Dentistry USIM  LEARNING OUTCOMES Explain the structural organization of living organism: from cell to system. Identify different types of tissues in human...

Topic 1: BASIC TISSUES Assoc. Prof. Dr. Siti Noor Adnalizawati bt Adnan Faculty of Dentistry USIM  LEARNING OUTCOMES Explain the structural organization of living organism: from cell to system. Identify different types of tissues in human body. Describe differential characteristics of 4 basic types of tissues and their locations: epithelial, connective, muscle and nervous tissues. Structural organisation of living organism Cell basic functional unit Tissue 4 types: epithelial, connective, muscular and nervous Organ brain, heart, kidney, ureter, urinary bladder etc. System urinary system, cardiovascular system, reproductive system etc  BASIC TISSUES Groups of cells similar in structure & function * Histology – study of tissues  EPITHELIUM Layer of the cells that cover the body surfaces or line the bodies cavities that open on it. -tracts/tubes (digestive tract, respiratory tract, blood vessels) -body cavities (peritoneal, pericardial and pleural cavities)  General Characteristics of Epithelium Little or no intercellular  Avascular–diffusion from substance. capillaries in the underlying Cell junctions are present. connective tissues. All cells in the basal layer rest  Regeneration–continuous on the basement membrane. wear & tear.  Classification of the covering epithelia -based on: i) Number of cell layers  single layer : simple  ≥ 2 layers : stratified  Pseudostratified ii) Shape of the cells  squamous, cuboidal, columnar iii) Presence of surface specializations Simple squamous Simple cuboidal Simple columnar Pseudostratified epithelium epithelium epithelium epithelium - Single layer of flattened cells with disc-shaped nuclei and sparse - Single layer of cube- - Single layer of tall - Appear as if it consists of cytoplasm like cells with and column-like more than one layer but only cells with oval a single layer is present with - allows passage of materials by rounded nuclei all cells resting on the diffusion and filtration - absorption , secretion nuclei basement membrane. - secretes lubricating substances in - kidney tubules, ducts - Absorption, - Cells are tall & short with body cavities & secretory portions secretion nuclei located at different - kidney glomeruli, air sacs of lungs, of small glands, ovary - intestines, gall levels lining of heart, blood vessels, lining surface bladder, uterine - Absorption, secretion tube - respiratory tract, epididymis, of ventral body cavities ductus deferens  Stratified squamous epithelium - protection –withstand physical abrasion & resist chemical injury Keratinised Non-keratinised - skin - all body openings (mouth, anus, vagina, oesophagus) Stratified cuboidal Stratified columnar Transitional epithelium epithelium epithelium - Rare - Resembles both stratified - Rare - large ducts of squamous & stratified cuboidal - ducts of sweat glands, exocrine organ, male - Basal cells : cuboidal or columnar mammary glands & urethra - Surface cells : dome shaped, salivary glands large & binucleated or - Protection, secretion - protection squamous-like – depends on degree of organ stretch. - lined most of the urinary tract such as ureters, urinary bladder & part of the urethra - allows distension  Specialization of epithelial cell surfaces Based on the function of the cells : Cilia Microvillus Stereocilia finger-like projection elongated, motile to increase the surface projections elongated, non- area of the cells absorption move material along the motile projections locations : intestine, cell surface increase surface kidney (PCT) location : respiratory area of absorption in LM, appear as location : striated border/brush epithelium border epididymis  Muscle Tissue Muscle cells/ fibers Long & narrow when relaxed Specialized contractile cells Move body parts or temporarily alter the shape (reduce the circumference of all or part) of internal organs. Associated connective tissue conveys nerve fibers and capillaries & binds into bundles or fascicles.  -Involuntary TYPES OF -Short broader cells – branching – anastomose with neighbouring fibres -Striations MUSCLE -1 or 2 nuclei-central -Intercalated disc -Less powerful than skeletal muscle but more resistant to fatigue Muscle of heart (myocardium) & adjacent portions of great vessels (aorta, vena cava) -Narrow spindle in shape - No striations - Single nucleus-central - Cylindrical in - Involuntary shape - Striations - Capable of slow but sustained - Multinuclei- contraction peripheral - Voluntary Walls of hollow viscera & blood Composes gross, attached vessels, iris and ciliary body of eye; to skeleton and fascia of attached to hair follicles of skin (arrector muscle of hair) limbs, body wall and head/neck  Provides support, binds together, and protects tissues and organs of Extracellular matrix (ECM) the body. ✓Support (forms framework of body CONNECTIVE - give strength & rigidity - Site for exchange of nutrients & tissue) ✓ Physical & immunological defense ✓ Repair TISSUES wastes - Site for important biological functions - Degraded & replaced throughout life ✓ Storage (water & electrolytes in ECM; fat in adipocytes) Fibers ✓ Transport Cells Fixed/ resident cells Ground substance Wandering/ migrant cells Glycosaminoglycans (GAGs) Proteoglycans Glycoproteins Cell type Product or activity Representative function Fibroblast, chondroblast, Production of fibers & structural osteoblast ground substances Adipose cell Storage of fat Energy reservoir, heat production Macrophage Secretion of cytokine, Defense (immunological) Phagocytosis, antigen processing & presentation Plasma cell Production of antibodies Defense (immunological) Mast cell & Basophil Liberation of Defense (allergy reaction) pharmacologically active molecules Neutrophil Phagocytosis Defense Eosinophil Allergic & vasoactive Defense (immunological) reactions, modulation of inflammatory process  Collagen fibres Body most abundant protein (30%) High tensile strength Synthesized by fibroblasts, chondroblasts, osteoblasts and odontoblasts > 25 types of collagen fibres – Molecular compositions, morphological Tropocollagen (collagen subunit, 3 α-chains characteristic, distribution, function arranged in triple helix) → fibrils → fibres  Particular important collagen fibres Type Structure Synthesized by Distribution I Fibres Fibroblasts, osteoblasts, odontoblasts, Skin, tendon, bone, smooth muscle cells blood vessel wall, dentin II Fibres Chondroblasts Cartilage, vitreous body III Fibres Fibroblasts Skin, muscle, blood vessel IV Meshwork Epithelial cells, muscle cells, Schwann All basement cells membrane V Fibres Fibroblasts, smooth muscle cells Fetal tissue, skin, bone, placenta, blood vessel VII Anchoring Fibroblasts Epidermal-dermal fibrils interface Fibrils Chondroblasts Cartilage , vitreous IX bone  Reticular fibres/ reticulin Synthesize by reticular cells (type of fibroblasts) Resembles collagen fibres, but thinner (0.1-1.5μm) Type III collagen & glycoprotein Branch extensively forming delicate network that surround small blood vessels & support the soft tissue of organs Major fibres in liver, kidney, glands & hematopoietic tissue (bone marrow, spleen)  Elastic fibres Formed by deposition of elastin into fibrillin scaffold – Glycine, proline, valine, alanine & lysine – Cross-linked via desmosine & isodesmosine (covalent reaction of 4 lysine) Wide range of diameter, branched extensively, no banding pattern Flexibility & elasticity – Arterial walls, lungs inner alveolar septa, bronchi & bronchioles, vocal ligaments & cartilages  Types of connective tissue CT with special Embryonic CT CT Proper properties ✓ -Mesenchymal ✓ -Loose CT CT ✓ -Elastic tissue ✓ -Dense regular ✓ -Mucous CT ✓ -Reticular tissue CT ✓ -Adipose tissue ✓ -Dense ✓ -Cartilage irregular CT ✓ -Bone  CONNECTIVE TISSUE PROPER Loose (areolar) connective Dense irregular connective Dense regular tissue tissue connective tissue - Equal component of CT, variety of - Few cells (fibroblast), thick collagen fibres cells, thin collagen fibres - Few cells (fibroblast), closely- with irregular orientation, length, thickness - Provide strength & elasticity, packed parallel-arranged collagen - Provides strength, resistant to stress from support structures under pressure & fibres all direction low friction -Provides strong attachment - Location: fascia, reticular layer of dermis, - Location: beneath epithelial layer between various structures periosteum of bone, joint capsules papillary layer of dermis, - Location: cornea, tendons, most serosal lining of peritoneal & ligaments & aponeuroses pleural cavities, around blood vessels & nerves  CONNECTIVE TISSUE WITH SPECIAL PROPERTIES Reticular CT Elastic CT Adipose tissue - Network of interlacing reticular - Parallel & free branching elastic - Adipose cells fibres & reticular cells fibres dominates predominates -Provide support & form stroma - Allows stretching of various - Function: thermal of organ organs insulator, energy reserve, -Location: stroma of liver, spleen, - Location: lung tissue, wall of shock absorber lymph nodes, around blood - Location: hypodermis, elastic arteries, trachea, bronchial vessels & muscles around heart & kidneys, tubes, true vocal cords, etc yellow bone marrow of long bones, etc  Avascular, tough, resilient connective tissue Cartilage ✓Prevent permanent distortion due to mechanical stress ✓Support soft tissue ✓Provide a sliding surface for joints ✓Facilitates bone movements ✓Necessary for growth of long bones Composition Cell, & fibers embedded in a firm, gel-like ECM. ✓ Cells Chondroblast (young cell). Chondrocyte (mature cell) ▪ 2-4 cells arranged in cluster as isogenous groups ✓ Fibers Collagen (type II) Elastic fibers ✓ Amorphous/ground substance Mucopolysaccharides  Hyaline cartilage Characteristics – Translucent, white & resilient Widespread type of cartilage, forming nearly all the fetal skeleton. Covered by perichondrium except in the articular cartilage of joints Location: Articular ends of bone Costal cartilages Cartilages of nose, larynx, trachea & bronchi Epiphyseal plate of a growing long bone Articular cartilage of movable joints  Elastic cartilage CARTILAGE Fibrocartilage Lines by perichondrium Chondrocytes Chondrocytes-seen as isogenous group - arranged in rows in combination with In matrix –collagen fibres & dense dense regular connective tissue. network of fine branching elastic fibres Collagen fibres take up the direction less susceptible to degenerative process parallel to those stresses. Location –intervertebral discs, pubic symphysis, menisci of knee joint, articular disc of temporomandibular joint Location Function * External ear, external acoustic meatus, –resistance to traction Eustachian tube (auditory tube), epiglottis force or great tensile and cuneiform cartilage in larynx. strength  BONE Components – Cells osteocyte, osteoblast other connective tissue cells – ECM substance. Organic (1/3) –Collagen fibers, – non-collagenous proteins, – amorphous mucopolysaccharide Inorganic (2/3) – calcium+ phosphate (hydroxyapatite) Other – Blood vessels, lymphatics, nerves. Functions of Bone  Highly vascularized & BONE mineralized connective tissue.  Specialized type of fluid connective tissue BLOOD TISSUE ▪ Light micrograph of blood smear (Wright’s/ Giemsa’s stain) - Basophilia (deep blue): methylene blue - Azurophilia (purple): azure dye - Eosinophilia (pink): eosin - Neutrophilia (lilac/ salmon pink)  Erythrocytes/ RBC Most abundant 7.5m diameter, 2.6 m thick Biconcave disc (large surface – to-volume ratio)– facilitate gas exchange Anucleate & no organelle Limited lifespan (120 days) Removed by spleen & bone marrow ▪ Packed with haemoglobin (O2 carrying protein) - 95% of dry weight of RBCs - 4 polypeptide subunit, heme group - Transport O2 to body tissue(oxyhaemoglobin) - Remove CO2 from body tissue (carmabinohaemoglobin) Reticulocytes Hematocrit ▪ Immature RBC recently released from bone marrow -Detect anemic state - Slightly larger than mature RBC -Estimate volume of packed - Small amount of mitochondria, RER & erythrocytes per unit volume of ribosomes blood - Maturation complete after 24-48 hrs of its -Proportion of blood release occupied by erythrocytes ▪ > 1% ↑ demand O2 carrying capacity - Male: 40-50%; female: 35- - Haemorrhage, anemia, recent ascent to high 45% altitude ▪ Larger nucleated cells, less numerous ▪ Part of immune system Leucocytes Neutrophils - Remove old cells & cell debris ▪ Most abundant granulocytes (60-70% of - Attack pathogens & foreign substances WBC) ▪ 2 groups ▪ 12-15μm diameter, 2-5 lobes nucleus - Granulocytes: neutrophil, ▪ Granules in cytoplasm eosinophil & basophil - Specific granules (substance - Agranulocytes: lymphocyte & monocyte involved in inflammatory ▪ Diapedesis response) - Exits capillaries by squeezing between endothelial cells - Azurophilic granules (lysosomes) - In response of infection/ inflammation ▪Function: phagocytose bacteria, acute inflammatory response Lymphocytes ▪20-25% of WBC Monocytes Eosinophils ▪Large spherical & indented nucleus with ▪2-4% of WBC scanty cytoplasm ▪10-15μm diameter, bilobed nucleus ▪8-12µm ▪Eosinophilic cytoplasmic granules ▪Function : mount immune response by ▪Function: allergic responses, phagocytose direct cell attack/ via antibodies antigen- antibody complexes, destroy ▪ T lymphocytes ▪3-8% of WBC parasitic worms - Major cells of cellular immune response - Produce cytokines (influences activity ▪12-20μm,horseshoe/ of other leukocytes) kidney-shaped nucleus Basophils ▪ B lymphocytes ▪Function: precursors ▪< 1% of WBC - Major component in humoral immunity to macrophage & - Differentiate into plasma cells (antibody ▪8-14μmdiameter, irregular lobed phagocytic secreting cells) nucleus cells in other organ ▪ Natural killer lymphocytes ▪Large basophilic granules - Destroy certain virus-infected cells & tumor ▪Function: precursor of mast cells cells, release histamine & * Cannot be distinguish morphologically - Cell surface molecule (CDmarkers) heparin ▪2-4μm anucleate cytoplasmic fragments of Thrombocytes megakaryocytes ▪Function: responsible for initial clot formation, release serotonin Haemostasis ▪ Complex process of body to stop bleeding - Vasoconstriction - Platelet plug formation - Blood coagulation  Cells Neurons Typically large, complex cells Highly-specialized cells. Do not divide in adults Many kinds of neurons,- all consist of a cell body (perikaryon/ soma) & neuronal processes - axon & dendrites. Characteristics of neurons: – Excitability – ability to respond to environmental changes or stimuli. – Conductivity – respond to stimuli by initiating electrical signals that travel Synapse quickly to other cells. – Secretion – upon arrival of the impulse at a distant location the neuron usually secretes a chemical neurotransmitter at a synapse that crosses the synaptic gap & stimulates the next cell.  Neuroglia of CNS Neuroglias (glial)  Neuroglia of PNS Neuroglias (glial)  Structural Classification of Neurons Based on no of processes Bipolar Multipolar 2 processes 3 or more extend from Unipolar (formerly known processes extend cell body as pseudounipolar) from the cell body – One is a fused single, short process – All are dendrites dendrite extends from cell except for a single – An axon body axon Rare Forms central & Most abundant in Found in some peripheral processes body Which together special sensory Major neuron type organs comprise an axon – Found mainly in PNS in CNS. – Retina of eye, – Common only in dorsal All motor neurons inner ear, root ganglia of spinal & interneurons of olfactory epithelium in cord & sensory ganglia brain & spinal of cranial nerves. the upper cord. region of nose. 38 Functional classification of neurons - based on the direction of conduction Sensory neurons – conduct impulses along afferent pathways to CNS for interpretation. Most unipolar neurons are sensory neurons. Interneurons – conduct impulses within CNS. Most multipolar neurons are interneurons Motor neurons – conduct impulses along efferent pathways from CNS to an effector (muscle/ gland). Some multipolar neurons are motor neurons Functional Classes of Neurons All bipolar neurons are sensory neurons – located in some special sense organs. Ex: bipolar cells of the retina involved with the transmission of visual inputs from eye to the brain (via an intermediate chain of neurons) Central Nervous System Within brain & spinal cord, – Gray matter - regions rich in unmyelinated axons along with nuclei, dendrites, glial cells – White matter - regions containing tracts of myelinated axons Hundreds of different neurons make up the CNS; – Purkinje neurons - large, unique , characterize the cortex of the cerebellum, – Pyramidal neurons – small layers form the cerebral cortex. *Tract = bundle of nerve fibers within the CNS *Nuclei = a collection of nerve cell bodies in the CNS Peripheral Nervous System Nerves - only in the periphery Cable-like organs in PNS = cranial & spinal nerves Consists of myelinated and unmyelinated axons (nerve fibers). Virtual microscopy Browse the following website: Histology Guide – Virtual histology laboratory http://www.histologyguide. com/slidebox/02- epithelium.html