Anatomy and Physiology Animal Tissue PDF

CHAPTER 1: ANIMAL TISSUE ======================== INTRODUCTION ============ A tissue is a group of cells that usually have a common origin in an embryo and function together to carry out specialized activities. ***Histology*** is the science that deals with the study of tissues. 4. **TYPES OF B...

CHAPTER 1: ANIMAL TISSUE ======================== INTRODUCTION ============ A tissue is a group of cells that usually have a common origin in an embryo and function together to carry out specialized activities. ***Histology*** is the science that deals with the study of tissues. 4. **TYPES OF BODY TISSUES** 1. **Epithelial tissue** covers the body surfaces and lines hollow organs, body cavities, and ducts; it also forms glands. This tissue allows the body to interact with both its internal and external environment. 2. **Connective tissue** protects and supports the body and its organs. Various types of connective tissues bind organs together, store energy reserves as fat, and help provide the body with immunity to disease-causing organism. 3. **Muscular tissue** is composed of cells specialized for contraction and generation of force. In the process, muscular tissue generates heat that warms the body. 4. **Nervous tissue** detects changes in a variety of conditions inside and outside the body and responds by generating electrical signals called *nerve action potential* (nerve impulses) that activate muscular contractions and glandular secretions.  **CELL JUNCTIONS** - Are contact points between the plasma membrane of tissue cells. Four most important types of cell junctions: ***TIGHT JUNCTIONS*** - Consist of weblike strands of transmembrane proteins that fuse together the outer surfaces of adjacent plasma membranes to seal off passageways between adjacent cells. - Holds cell together so there is no extracellular space between them. ***GAP JUNCTIONS*** - At gap junctions, membrane called connexins form tiny fluid-filled tunnels called connexons that connect the neighboring cells. - Forms an intercellular passageway between the membranes of adjacent cells. - Allows the cells in a tissue to communicate with one another. ***ADHERENCE JUNCTIONS*** - A dense layer of proteins on the inside of the plasma membrane that attaches both to membrane proteins and to microfilaments of the cytoskeleton. - Acts like a belt that holds the epithelial cells together called **adhesion belts**. ***DESMOSOMES*** - Contains plaque and have transmembrane protein like adherence junctions that extend into the intercellular space between adjacent cell membranes and attach to one another. - Holds cell together like push button on a jacket. - Attaches to cytoskeleton known as intermediate filaments, which consists of protein keratin. **EPITHELIAL TISSUE** An epithelial tissue consists of cells arranged in continuous sheets, in either single or multiple layers. Epithelial is arranged in two general patterns in the body: 1. Covering and lining various surfaces. 2. Forming the secreting portions of glands. Functionally, epithelial tissue protects, secretes (*mucus, hormones, and enzymes*), absorbs (*nutrients in the gastrointestinal tract*), and excretes (*various substances in the urinary tract*). **Characteristics of Epithelial Tissue** - This tissue is highly cellular with little or no extracellular material. - Are avascular (no blood cells; uses diffusion) - Are capable of regeneration (easily reproduce) - Exhibits polarity (structures differ from one another --roles and appearances) **APICAL SURFACE** - The apical surface of an epithelial cell faces the body surfaces, a body cavity, the lumen (interior space) of an internal organ, or a tubular duct that receives cell secretion. - May contain cilia and microvilli. **LATERAL SURFACE** - The lateral surfaces of an epithelial cell, which face the adjacent cells on either side, may contain tight junctions and/or gap junctions. **BASAL SURFACE** - The basal surface of an epithelial cell is opposite the apical surface. - It is the deepest layer of epithelial cells that adheres to extracellular materials such as the basement membrane. - Is a thin extracellular layer that commonly consist of two layers, the basal lamina and reticular lamina. ***Basal lamina*-** is closer to---and secreted by---the epithelial cells. Contains proteins such as laminin and collagen. ***Reticular lamina***- is closer to the underlying connective tissue and contains proteins such as collagen produced by connective tissue cells called fibroblasts. **CLASSIFICATION OF EPITHELIAL TISSUES** 1. **Arrangement of cells in layers** a. *Simple epithelium* is a single layer of cells that functions in diffusion, filtration, secretion, or absorption. **Secretion** is the production and release of substances such as mucus, sweat, or enzymes. **Absorption** is the intake of fluids or other substances such as digested food from intestinal tract. b. *Pseudostratified epithelium* appears to have multiple layers of cells because the cell nuclei lie at different levels and not all cells reach the apical surface. Others secrete mucus. c. *Stratified epithelium* consists of two or more layers of cells that protect underlying tissues in locations where there is considerable wear and tear. 2. **Cell Shapes** a. *Squamous cells* are thin, which allows for rapid passage of substances through them. b. *Cuboidal cells* are as tall as they are wide and are shaped like cubes or hexagon. They may have microvilli at their apical surface and function in either secretion or absorption. c. *Columnar cells* are much taller than they are wide, like columns, and protect underlying tissues. Their apical surfaces may have cilia or microvilli, and they often are specialized for secretion and absorption. d. *Transitional cells* change shape, from squamous to cuboidal and back, as organs such as the urinary bladder stretch (distend) to a larger size and then collapse to a smaller size. e. *Glandular* has goblet (goblet cells) area which produces mucus to lubricate the surface. It is a unicellular exocrine "gland" interspersed between the columnar or pseudostratified columnar epithelial cells of mucus membrane. **SIMPLE SQUAMOUS EPITHELIUM**  **SIMPLE CUBOIDAL EPITHELIUM** **NONCILIATED SIMPLE COLUMNAR EPITHELIUM**  **CILIATED SIMPLE COLUMNAR** **NONCILIATED PSEUDOSTRATIFIED COLUMNAR**  **CILIATED PSEUDOSTRATIFIED COLUMNAR** **STRATIFIED SQUAMOUS**  **STRATIFIED CUBOIDAL** **STRATIFIED COLUMNAR**  **TRANSITIONAL** ***Epithelial tissues work for protection, secretion, selective permeability, sensation, and surface parallel transport.*** **CONNECTIVE TISSUE** **Connective tissue is one of the most abundant and widely distributed tissues in the body. In its various forms, connective tissue has a variety of functions. It binds together, support, and strengthens other body tissues; protects and insulates internal organs; compartmentalizes structures such as skeletal muscles; serves as a major transport system within the body; is the primary location of stored energy reserved; and is the min source of immune response.** **Characteristics of Connective Tissue** - **It consists of two basic elements: extracellular matrix and cells.** - **The extracellular matrix consists of protein fibers and ground substances. It determines much of the tissue's qualities.** - **Does not occur in body surface.** - **Highly vascular; that it has a rich blood supply.** - **Except for cartilage, which is avascular, connective tissue is supplied with nerves.** **COMPONENTS OF CONNECIVE TISSUE** **FIBERS** 1. ***Collagen fibers* -- are strong, flexible bundles of the protein collagen, the most abundant protein in your body. These are flexible but resist stretching.** 2. ***Reticular fibers* -- are made of collagen and glycoproteins. They provide support in blood vessel walls and form branching networks around various cells (fat, smooth muscle, nerve).** 3. ***Elastic fibers* -- are stretchable but strong fibers made of proteins, elastin, and fibrillin. They are found in skin, blood vessels, and lung tissue.** **CELLS** **Intrinsic** - **do not move** - **fibroblast, undifferentiated mesenchymal cells, pigment, adipocytes, pericytes, mast, macrophages.** **Migrant/transfer** - **moving cells** - **macrophages, lymphocytes, plasma, neutrophils, eosinophils, and basophils.** **CLASSIFICATION OF CONNECTIVE TISSUE** **LOOSE CONNECTIVE TISSUE PROPER** **The fibers of loose connective tissue are loosely arranged between cells. Found between many organs where it acts both to absorb shock and bind tissues together.** a. ***Areolar Connective Tissue*** - **is one of the most widely distributed connective tissues.** - **Fills the spaces between muscle fibers, surrounds blood and lymph vessels, and supports organ in abdominal cavity.** - **Underlies most epithelial, including between our skin and our muscles or bones.** - ***Function*: strength, elasticity, support.**  b. ***Adipose Tissue*** - ***Has cells derived form fibroblast* (adipocytes) that are specialized for storage of triglycerides (fats) as large, centrally located droplet.** - ***White adipose*: contains lipid storage and can serve as insulation.** - ***Brown adipose*: thermogenic- releases metabolic heat. Found mainly in the neck and clavicle.** - ***Function***: serves as an energy reserve, support and protect organs. c. ***Reticular Connective Tissue*** - **is a fine interlacing network of reticular fibers (thin form of collagen fiber) and reticular cells.** - **Mesh-like, supportive framework for soft organs such as lymphatic tissue, the spleen, and the liver.** - ***Function:* forms stroma of organs; binds smooth muscle tissue cells; filters and removes worn-out blood cells in spleen and microbes in lymph nodes.** **DENSE CONNECTIVE TISSUE PROPER** **The type of connective tissue proper that contains more fibers, which are thicker and more densely packed, but have considerably fewer cells than loose connective tissue.** a. ***Dense Regular Connective Tissue*** - **Forms a shine white extracellular matrix; mainly collagen and fibers regularly arranged in bundles with fibroblasts in rows between them.** - **Fibers are parallel to each other, enhancing tensile strength in the direction.** - ***Function*: provides strong attachment between various structures. Can withstand pulling along long axis of fibers.**  b. ***Dense Irregular Connective Tissue*** - **is made up of collagen fiber; usually irregularly arranged with a few fibroblasts.** - ***Function:* provides tensile strength in many directions.** c. ***Elastic Connective Tissue*** - **Contains predominantly elastic fibers with fibroblasts between them; unstained tissue is yellowish.** - ***Function*: allows stretching of various organs; is strong and can recoil to original shape after being stretched. Elasticity is important to normal functioning of lung tissue and elastic arteries.**  **SUPPORTING CONNECTIVE TISSUE** **This type of mature connective tissue includes cartilage and bone.** **CARTILAGE** - **Consists of dense network of collagen fibers and elastic fibers firmly embedded in chondroitin sulfate, a gel-like component of the ground substance.** a. ***Hyaline Cartilage*** - **Contains a resilient gel as ground substances and appears in the body as a bluish-white, shiny substance.** - **Provide support to the structures in which it is found, with some flexibility, and it forms smooth surface.** - ***Function*: provides smooth surfaces for movement at joints, flexibility, and support; weakest type of cartilage and can be fractures** b. **Fibrocartilage** - **Has chondrocytes among clearly visible thick bundles of collagen fibers within extracellular matrix; lacks perichondrium.** - **Is somewhat flexible and capable of withstanding.** - ***Function*: support and joining structures together. Strength and rigidly make it the strongest type of cartilage.**  c. ***Elastic Cartilage*** - **has chondrocytes in threadlike network of elastic fibers within extracellular matrix; perichondrium present.** - **Provides rigidity, but with flexibility than hyaline cartilage because elastic fibers return to their original shape after being stretched.** d. ***Bone*** - **Provides great strength and support and protects internal organs such as brain.** - **Bone also provides attachment sites for muscles and ligament.** - **Compact bone tissue- consists of osteons that contain lamellae, lacunae, osteocytes, canaliculi, and central canals. By contrast, spongy bone tissue consists of thin columns called trabecular; spaces between trabeculae are filled with red bone marrow.** - ***Function*: support, protection, storage; house blood-forming tissue; serves as levers that act with muscle tissue to enable movement.**  **FLUID CONNECTIVE TISSUE** **This is the final type of mature connective tissue. A liquid connective tissue has a liquid as its extracellular matrix.** a. ***Blood*** - **One of the liquid connective tissues has liquid extracellular matrix called blood plasma and formed elements.** - **Blood transport oxygen, carbon dioxide, hormones, nutrients, and waste products.** - **Mostly migrant cells** - **Blood plasma is the most component of the blood; also consist of RBC and WBC, platelets** - ***Function*: supporting and connective tissues; protection, defense, transport, energy transform** **MUSCULAR TISSUE** **Muscular tissue consists of elongated cells called muscle fibers or myocytes that can use ATP to generate force. It produces body movements, maintains posture, and generate heat.** **Characteristic of Muscular Tissue** - **Excitability** - **Contractability** - **Extensibility** - **Elasticity** a. ***Skeletal Muscle Tissue*** - **Consist of long, cylindrical, striated fibers.** - **Skeletal muscle fibers vary greatly in length, from a few centimeters in short muscles to 30-40 cm in the longest muscles.** - **A muscle fiber is roughly cylindrical, multinucleated cell with nuclei at the periphery.** - **Forms the muscles that move our bones and joint.** - **For voluntary movement.**  b. ***Cardiac Muscle Tissue*** - **Consists of branched, striated fibers with usually only one centrally located nucleus.** - **Attach end to end by transverse thickening of plasma membrane called intercalated discs, which contain desmosomes and gap junctions.** - **Found in the heart wall.** - ***Function:* pumps blood to all parts of body.** - **Involuntary control.** c. ***Smooth Muscle Tissue*** - **Consists of nonstriated fibers and thousand times smaller than skeletal muscle.** - ***Function*: motion (constriction of blood vessels and airways, propulsion of foods through gastrointestinal tract, contraction of urinary bladder and gallbladder)** - **Involuntary control**  **NERVOUS TISSUE** **Despite the awesome complexity of the nervous system, nervous tissues consist of only two principal types of cells; neurons and neuroglia.** **Neurons** - **Or nerve cells are sensitive to various stimuli.** - **They convert stimuli into electric signals called nerve action potentials (nerve impulses) and conduct these to other neurons, to muscle tissue, or to glands.** - **It consists of three basic parts; cell body and two kinds of cell processes---dendrites and axons.** - **Cell body- contains the nucleus and other organelles.** - **Dendrites- are tapering, highly branched, and usually short cell processes.** - **Axon- of a neuron is a single, thin, cylindrical process that may be very long. It is the output portion of a neuron, conducting nerve impulses toward another neuron or to some other tissue.** a. ***Nervous Tissue*** - **Consists of neurons, which consist of cell body and processes extending from cell body; and neuroglia, which do not generate or conduct nerve impulses but have other important supporting functions.** - ***Function*: exhibits sensitivity to various types of stimuli; converts stimuli into nerve impulses; conducts nerve impulses to other neurons, muscle fibers, or glands.** **\ ** CHAPTER 2: INTEGUMENTARY SYSTEM =============================== **INTEGUMENTARY SYSTEM** Skin is the largest organ. Integumentary system is the largest body system in terms of surface area. 16% of the body mass came from the skin.  **THE THREE LAYERS OF THE SKIN** **EPIDERMIS** - Layer of epithelial issue that rest on the dermis.  - Consist of highly keratinized squamous epithelial cell. - upon/over the skin - Thinnest layer **DERMIS** - Layers of dense connective tissue.  - Other structures of the skin: hair follicles, nerve endings, and blood vessels; glands.  - Quite thick **HYPODERMIS ** - Loose connective tissue that contains about the half the body's stored fat. - Is not a layer of the skin.  - The thickest   **EPIDERMIS** - Thinnest layer  - Highly avascular  - Superficial layer of the skin; exposed directly to the environment.  - Composed of keratinocytes.  - Most of the cells are dead, but highly keratinized.  - 4-5 layers  - 4 layers of stratum is described as thin; if 5, it is described as thick  ***Stratum Basale/germinativum *** - Single layer of cell; composed of basal cells. - Basal cells (stem cells) are precursors of keratinocytes.  - Continuously doing mitosis.      ***Stratum spinosum*** - Came from the word spiny because there are projections on the outer part of the cell.  - Layer of keratinocytes.  ***Stratum granulosum*** - Layer of flattened cells.  - Cells are granulated due to the presence of keratin.  - Keratin allows the skin to have a color; makes skin tough.  ***Stratum lucidum*** - Layer of dead cells. - Not all of the body parts covered by the skin is covered with stratum lucidum; mostly in the palm of the hand and sole of the foot.  - Eleidin makes the layer transparent, lucid in color.  ***Stratum corneum*** - Superficial epidermal layer.  - Came from the word cornified, means highly keratinized; cells are dead.   **MERKEL CELLS AND LARGERHANS CELL** **Merkel Cell** - Responsible for stimulating sensory nerves that the brain perceives as touch. - Found in stratum basale. - A cell that acts as a receptor; receives stimulus from the external environment that will be directly move to the brain, as a sense of touch.  - Abundant in the palms of your hand and sole of your feet.  **Langerhans** - Function as macrophages by engulfing bacteria, foreign particles, and damaged cells that occur in this layer.  - Found in stratum spinosum  - For immunity - Protects us from invading foreign materials that try to invade the skin.  **KERATINOCYTES AND MELANOCYTES** **Keratinocytes** - Cell that manufactures and stores the protein keratin.  - Allows the structure to harden.  **Melanocytes** - A cell that produces the pigment melanin.   - Pigmentation happens when we are exposed to the uv rays that comes from the sun.  - Melanosome is a vesicle that transfer the melanin produced by melanocytes. Purpose is to cover your nucleus.  ***UV rays' type*** ***UVB**- is not that harmful and can penetrate your skin but not the deepest layer.* ***UVA**- can cause skin cancer.* **DERMIS** **Papillary layer** - The upper dermal region.  - *Dermal papillae*; a finger-like projection; results to the formation of fingerprints.  **Reticular layer** - The deepest dermal region.  - See most of your sweat gland.  - *Arrector pili muscle;* causes to feel goosebumps. We experienced that because of the contraction on arrector pili.   **FACTORS TO SKIN COLOR** 1. The amount and kind of melanin in the epidermis. Types: eumelanin--black to brown, pheomelanin--reddish.  2. The amount of carotene deposited in the stratum corneum and subcutaneous tissue. Carotene is a protein inside the cell of the skin (orange color).  3. The amount of oxygen bound to hemoglobin in the dermal blood vessels.  4. The emotional stimuli.  **SKIN COLOR MEANING** 1. Erythema - redness 2. Pallor - blanching (paleness) 3. Jaundice - yellow cast 4. Bruises - black and blue marks **APPENDAGES OF THE SKIN** **CUTANEOUS GLAND** ***Sebaceous gland*** - A type of oil gland found all over the body and helps to lubricate and waterproof the skin and hair.  - Produces sebum that lubricates the skin. Which is produced based on hormonal changes.  ***Sweat Glands*** - Produces sweat to cool the body. - Eccrine sweat gland; produces the regular sweat. Known to be hypotonic. Found in most body parts.  - Apocrine sweat gland; usually associated with hair follicles in densely hairy areas, such as armpits and genital regions. High in organic substances.  ***Nails*** - Is a thin plate, consisting of layers of dead stratum corneum cells that contain a very hard type of keratin.  - Not vascular, but the bed of the nail is vascular.  ***Hairs*** - Highly keratinized - Is a keratinous filament growing out of the epidermis. It is primarily made of dead, keratinized cells.  - Cuticle is a fatty substance that protects the hair.  - Medulla is the core of the hair - Cortex surrounds the medulla - The strand if curly or straight is due to the cortex of the hair.  - Follicle undergoes mitosis.  - Used to protect the skin, even for insulation. Filters the materials that enters the skin.  *Arrector pili contracts in response to nerve signals. * **Cycles of hair growth** 1. **ANAGEN PHASE-** growing phase (2-7years) 2. **Catagen phase** - transition phase (active growth, 2-3 weeks) 3. **Telogen phase** - resting phase (2-4 months)  It will grow and regrow **INTEGUMENTARY SYSTEM** - Comprises of the skin and its derivatives **Functions of the skin** - Covering - Protection - Thermal regulation - Excretion of urea and uric acid - Synthesis of vitamin d Chromatophore - Is a specialized structure in the skin of the frog that enables them to get oxygen from their surroundings.  **\ ** CHAPTER 3: SKELETAL SYSTEM ========================== **BONE** **A bone is an organ made up of several different tissues working together; bone (osseous) tissue, cartilage, dense connective tissue, epithelium, adipose, and nervous tissue. The study of bone disorders is referred to as *osteology*.** **BASIC FUNCTIONS** 1. **Support. The skeleton serves as the structural framework for the body by supporting soft tissues and providing attachment points for the tendons of skeletal muscles.** 2. **Protection. It protects most important internal organs from injury.** 3. **Assistance in movement**. Most skeletal muscles attach to bones; when they contract, they pull on bones to produce movements. 4. **Mineral homeostasis (storage and release)**. It stores several minerals, especially calcium and phosphorus, which contribute to the strength of bone. On demand, bone releases minerals into the blood to maintain critical mineral balances and to distribute mineral to other parts of the body. 5. **Blood cell production**. Within certain bones, a connective tissue called red bone marrow produces red blood cells, white blood cells, and platelets, a process called hemopoiesis. Present in developing bones of fetus and in some adult bones. With increasing age, much of the bone marrow changes from red to yellow. 6. **Triglyceride storage**. **Yellow bone marrow** consists mainly of adipose cells, which store triglycerides. The stored triglycerides are a potential chemical energy reserve. **TWO IMPORTANT STRUCTURES** **CARTILAGE** - Nonvascular type of supporting connective tissue that is found throughout the body.  - Receives nutrients via filtration or diffusion  ***Hyaline Cartilage*** - Has a smooth surface and is the most common of the three types of cartilage. ***Fibrocartilage*** - Is the toughest of the three types of cartilage.  - Can withstand pressure and force.  ***Elastic Cartilage*** - Provides support - Elastic in the sense that you can stretch it and back to its original state.  Cartilage is a connecting supportive tissue without blood vessels. Cartilage is not that hard compared to bone.  Hyaline cartilage has a high concentration of chondrocyte. ***Lacunae*** is a space where chondrocytes are placed.  ***Fibrocartilage***-- collagen fibers are high and is spread out in the matrix.  **BONE/ OSSEOUS TISSUE** - - - - - - - - - - ***Femur***- the longest bone of the body.  At the top of the of the femur is where red bone marrow situated, which produces blood cells.  *Spongy bone area produces red bone marrow. * *Yellow bone marrow is produced in the compact bone area*. It produces fats.  **CLASSIFICATION OF BONES** **Flat Bone** - Thin and curvy  **Long bone** - Cylinder like shape longer than it is wide **Sesamoid bone** - Small and round: embedded in tendons **Irregular bone** - Complex shape **Short bone** - Cube-liked shape: approximately equal in length, width, and thickness **Pneumatized** - Hollow or full of air pockets.  **LONG BONE** **Metaphysis** - The narrow area that contains the epiphyseal plate (growth plate), a layer of hyaline cartilage in a growing bone.  - Narrow area between epiphysis and diaphysis.  **Medullary cavity** - Is the hollow region in diaphysis, which is filled with yellow marrow.  **Diaphysis** - Is the tubular shaft that runs between the proximal and distal ends of the bone.  **Distal epiphysis** - Is the wider section at each end of the bone - Normally called head of the bone.  **Articular cartilage** - Covering of the bone to eliminate friction.  **Metaphysis and epiphysis** **Periosteum ** - location of the bone where most of the nutrients are coming true - A fibrous membrane, contains blood vessels, nerves, and lymphatic vessels that nourish compact bone.  **Endosteum** - A delicate membranous lining, where bone growth, repair, and remodeling occur.   **FLAT BONE** **BONE CELLS**  **Osteocyte** - Maintain mineral concentration of matrix - Primary mature cell of the bone - Do not undergo mitotic division - Found in lacunae, surrounded by tissue.  **Osteoblast** - Bone formation - Never undergo mitotic division. - Found in growing area of the bond. Releases, secretes, synthesizes collagen matrix. Capacity to release calcium salt.  - Once calcified, they surround the osteoblast, once trapped become the osteocytes.  **Osteogenic cell** - Develop into osteoblasts - Known to be stem cells for osteoblast. - Undergo mitosis **Osteoclast** - Bone resorption. - Reabsorbed the presence of calcium - Remove the components of the bone that are not needed.  - Found on the surface of the bone ***Hydroxyapatite*** - Produced due to the reaction by calcium phosphate and calcium carbonate.  - This makes the bone part **BONE TISSUE** **COMPACT BONE** - Denser, stronger of the two types of bone tissue. It can be found under periosteum and in the diaphysis of long bones, where it provides support and protection.  ***Osteon*** - Comprises Concentrix lamellae where you can see the lacunae in which you can see the osteocytes.  The middle part is called the haversian canal, where blood vessels, arteries and veins, lymphatic vessels, and nerves to provide nutrients to the cells and other components of the tissue.  ***Perpetrating canal*** allows some vessels to move in some parts of the bone.   **SPONGY BONE** - Contains osteocytes housed in lacunae, but they are not arranged in concentrix circles.  - Shows mesh-like arrangement.  The spaces allow movement.  **BLOOD AND NERVES SUPPLY** - Vessels enter the bone via nutrient foramen.  - As the blood passes through the marrow cavities, it is collected by veins, passing out of the bone through the foramina.  - Blood low in oxygen, high in waste materials via the veins and move out of the bone.  - Nerves follow the same paths into the bone, where they tend to concentrate in the more metabolically active regions of the bone.   **OSTEOGENIC PATHWAYS** **Intramembranous ossification ** - Process involves the direct conversion of mesenchyme to the bone.  - For your bones to develop - Happens from fetal to development stage The ossification center will be the one that will be calcified.  - Precursor of osteoblast.    *Your mesenchyme becomes your osteocytes and the osteocytes turns to become bone tissue. * - *From mesenchyme to bone* **Endochondral ossification ** - Involves the replacement of hyaline cartilage with bone - Cartilage become the bone.  - There is ossification center, where bone starts to develop.   **INTERSTITIAL BONE GROWTH** **Reserved zone** - The reserved zone contains small chondrocytes within the matrix that do not participate in bone growth but secure the epiphyseal plate to the osseous tissues of the epiphysis. **Proliferative zone** - The proliferative zone makes new chondrocytes via mitosis to replace those that die at the diaphyseal end of the plate.  **Maturation and hypertrophy** - Chondrocytes are older and larger than those in the proliferative zone.  **Calcified matrix** - Chondrocytes are dead because the matrix around them has calcified and connects the epiphyseal plate to the diaphysis.   As bone matures, the epiphyseal plate progress to an epiphyseal line. Epi plates are visible in a growing bone. **APPOSITIONAL BONE GROWTH**  **AXIAL AND APPENDICULAR** **Axial skeleton** - 80 bones - Forms the vertical, central axis of the body and includes all bones of the head, neck, chest, and back.  **Appendicular** - 106 bones - Includes all bones of the upper and lower limbs, plus the bones that attach each limb to the axial skeleton.  **BONY MARKINGS** **ARTICULATIONS** - 1. **Functional Classification** - ***Synarthrosis*** - an immobile or nearly immobile joints - ***Amphiarthrosis*** - a joint that has limited mobility - ***Diarthrosis*** - a freely mobile joint **DIARTHROSIS** **Nonaxial joint** - Do not move about a plane - Goes against the plate **Uniaxial joints** - a=only allows for a motion in a single plane **Biaxial joint** - A metacarpophalangeal joint of the hand (knuckle joint)  **Multiaxial joint** - A joint that allows for several directions of movements 2. **Structural classification** ***Fibrous joint*** - Where the adjacent bones are united by fibrous connective tissue - Suture- narrow fibrous joint found between most bones and skull - Syndemosis- which two parallel bones are united to each other by FCT - Gomphosis- between the roots of a toth and the bony socket in the jaw into which the tooth fits. ***Cartilaginous joint*** - The bones are joined by hyaline cartilage or fibrocartilage.  - Sychondrosis - the bones are joined by hyaline cartilage - Symphysis- bones joined by fibrocartilage ***Synovial joint*** - The bones are not directly connected but instead come into contact with each other within a joint cavity that is filled with lubricating fluid.  -  **JOINTS THAT MOVE IN THE BODY** **Pivot joint** - Allow for rotation around an axis, which allows for side-to-side rotation of the head.  - biaxial **Hinge joint** - Works like a door hinge - Uniaxial **Saddle joints** - Can move up and down and back and forth **Ball and socket joint** - Allows wide range of movement in almost any direction - Multiaxial **Condyloid joint** - Are elongated ball-and-socket joints **Plane joint** - Allow for limited gliding movement between bones - Uniaxial **MOVEMENTS OF THE BODY** - Flexion - Extension  - Abduction  - Rotation- lateral/medial - Pronation - Supination - Plantar flexion - Inversion  - Protection and retraction - Elevation and depression - Opposition