Histology 1-10 PDF - Basic for PT1 2024-25

HISTOLOGY Prof. Dr. Marwa G.A. Hegazy Basic for PT1 2024-25  LO’s (Lecture1)  Objective 1 – The student will be able to: ❑ Identify the structure of living cell plasma membrane, cytoplasm, nucleus and their functions. ❑ Understand structure and function of membranous o...

HISTOLOGY Prof. Dr. Marwa G.A. Hegazy Basic for PT1 2024-25  LO’s (Lecture1)  Objective 1 – The student will be able to: ❑ Identify the structure of living cell plasma membrane, cytoplasm, nucleus and their functions. ❑ Understand structure and function of membranous organelles (ER, golgi, lysosomes, mitochondria) Basic for PT1 2024-25  HISTOLOGY & HUMAN CELL STRUCTURE Histology is the science that deals with the microscopic structure of cells& tissues. Basic for PT1 2024-25  The Cell The basic unit of life The structural and functional unit of all living tissues Basic for PT1 2024-25  Types of microscopes Light Microscope Transmission (LM) Electron Microscope Basic for PT1 2024-25 Cell Diversity ◼ Cells within the same organism show Enormous Diversity in: ◼ Size ◼ Shape ◼ Internal Organization Basic for PT1 2024-25 1. Cell Size ◼ Female Egg - largest cell in the human body; seen without the aid of a microscope ◼ Most cells are visible only with a microscope. Basic for PT1 2024-25  2. Cell Shape ◼ Diversity of form reflects a diversity of function. ◼ THE SHAPE OF A CELL DEPENDS ON ITS FUNCTION. Basic for PT1 2024-25 3. Internal Organization Cell membrane Cytoplasm Prokaryotic Cell Cell membrane Cytoplasm Eukaryotic Cell Nucleus Organelles Basic for PT1 2024-25 Types of the cell ? Basic for PT1 2024-25 Compare and Contrast Prokaryotes Eukaryotes Nucleus Endoplasmic reticulum Cell membrane Golgi apparatus Contain DNA Lysosomes Ribosomes Vacuoles Cytoplasm Mitochondria Cytoskeleton Basic for PT1 2024-25  Prokaryotic Examples ONLY Bacteria Basic for PT1 2024-25 EUKARYOTIC CELLS Two Kinds: Plant and Animal Basic for PT1 2024-25  Eukaryotic Example Animal Cell Basic for PT1 2024-25 Section 7-2 Eukaryotic Example Vacuole Smooth endoplasmic reticulum Ribosome (free) Chloroplast Ribosome (attached) Cell Membrane Cell wall Nuclear envelope Nucleolus Golgi apparatus Nucleus Mitochondrion Rough endoplasmic reticulum Plant Cell Basic for PT1 2024-25  Venn Diagrams Compare and Contrast Animal Cells Plant Cells Cell membrane Ribosomes Nucleus Endoplasmic reticulum Cell Wall Centrioles Golgi apparatus Lysosomes Chloroplasts Vacuoles Mitochondria Cytoskeleton Basic for PT1 2024-25  The cell Cytoplasm Nucleus Basic for PT1 2024-25 Section 7-1 Cytosol and Cytoplasm ◼ The cytosol is the "soup" within which all the other cell organelles reside and where most of the cellular metabolism occurs. ◼ The cytoplasm is a collective term for the cytosol plus the organelles suspended within the cytosol Basic for PT1 2024-25  Cytoplasm Cytosol Organelles Inclusions It is a viscous Permanent Temporary colloidal solution living structures, formed of : structures not essential Protein- essential for for vitality of carbohydrates- vital processes cells. lipids- enzymes- of the cell. They may be minerals- ions- salts. present or Basic for PT1 2024-25 absent  Organelles A. Membranous B. Non-membranous Organelles Organelles 1. Cell membrane (plasma 1. Ribosomes membrane). 2. Cytoskeleton 2. Mitochondria. 3. Endoplasmic reticulum (rough & smooth). 4. Golgi apparatus. 5. Lysosomes Basic for PT1 2024-25  A. Membranous Organelles ◼ The Plasma membrane (Cell membrane) ◼ The boundary of the cell. ◼ Composed of three distinct layers. ◼ Two layers of fat and one layer of protein. Basic for PT1 2024-25  L.M.: Difficult to be seen (H&E) as it is very thin. It can be demonstrated when stained with silver (Ag). E.M.: Appears as 2 electron- dense (dark) lines, separated by an electron-lucent (light) one (trilamellar). Basic for PT1 2024-25  Molecular Structure of Cell Membrane:- 1-Lipid 3- 2- Protein Component Component Carbohydrate : Component a) b) a) Extrinsic b) Intrinsic Phospholipid Cholesterol protein protein molecules molecules (peripheral) (integral) Basic for PT1 2024-25  Molecular Structure of Cell Membrane:- 1- Lipid Component: a) Phospholipid molecules: (lipid bilayer). Each molecule has a head and two tails. Head Tails Hydrophilic (has great Hydrophobic (has no affinity to aqueous affinity to aqueous solutions). solutions). called polar as it is charged. called non-polar as it is non- charged. Heads are arranged at the Tails are directed inwards, outer and inner surfaces. they face each other in the center. Function: selective permeability to perform a barrier between Basic for PT1 2024-25 internal and external environment of the cell  b) Cholesterol molecules: Present among the hydrophobic tails to stabilize the cell membrane & modulate the fluidity. Basic for PT1 2024-25 2- Protein Component: a) Extrinsic (peripheral): small molecules, loosely attached at both sides of the lipid bilayer b) Intrinsic (integral): embedded in the lipid bilayer in form of : Small molecules Large molecules (Trans-membrane protein): extend across the membrane and act as pathways for ions and molecules. ❑ Channel proteins for transport of ions and water. ❑ Carrier proteins for transport of small polar molecules as glucose and ions as Na pump. Basic for PT1 2024-25  3-Carbohydrate Component At the external surface, (glycoproteins and glycolipids), forming the cell coat (Glycocalyx). Function: ◼ it includes receptors that has important interactions: ◼ a) Cell adhesion: helps in attachment of some cells to each other & to extracellular matrix. ◼ b) Cell immunity: It binds antigens to the cell surface Basic for PT1 2024-25 Basic for PT1 2024-25  Bulk transport moving substances from a) Endocytosis b) Exocytosis the cytoplasm to the outside 3- Receptor-mediated endocytosis (selective 1- Phagocytosis 2- Pinocytosis transport) Specific molecules the process of the process of bind to their receptors engulfing solid engulfing fluid that accumulate at the particles by the droplets by the cell cell membrane which cell membrane to invaginates and membrane to form pinches off, forming a form a pinocytic vesicles. coated vesicle phagosome containing the specific (phagocytic molecules and their vesicle) receptors. Basic for PT1 2024-25 Basic for PT1 2024-25 The Nucleus ◼ Brain of Cell ◼ Bordered by a porous membrane - nuclear envelope. ◼ Contains thin fibers of DNA and protein called chromatin. ◼ Rod Shaped Chromosomes ◼ Contains a small round nucleolus ◼ produces ribosomal RNA which makes ribosomes. Basic for PT1 2024-25 Endoplasmic Reticulum ◼ Complex network of transport channels. ◼ Two types: 1. Smooth- ribosome free. Functions in lipid and steroid hormone synthesis, breakdown of lipid-soluble toxins in liver cells, and control of calcium release in muscle cell contraction. 2. Rough - contains ribosomes and releases newly made protein from the cell. Basic for PT1 2024-25  Rough Endoplasmic Reticulum Smooth Endoplasmic Reticulum (sER) (rER) Site Abundant in protein-forming cells as Abundant in steroid-forming cells as in in plasma cells. endocrine glands. L.M. basophilic due to the presence of When abundant, it causes cytoplasmic ribosomes (rRNA). acidophilia E.M. Parallel, flattened cisternae studded Branching, anastomosing tubules or vesicles, with ribosomes on their outer surface. with no ribosomes on their outer surface Functions 1. Protein synthesis by ribosomes. 1- Synthesis of Lipids (as phospholipids & 2. Initial glycosylation. Cholesterol) and steroid hormones as testosterone and cortisone. 3. Packing of formed protein in 2- Detoxification of drugs, hormones & alcohol membranous vesicles "Transfer (in liver cells). vesicles" to transfer protein to 3- Muscle contraction and relaxation in Golgi. skeletal muscle cells (storage and release of 4. Intracellular transport. Ca+2 ) 4- Breakdown of glycogen to glucose in liver cells. 5- Intracellular transport Basic for PT1 2024-25  Golgi Apparatus ◼ A series of flattened sacs that modifies, packages, stores, and transports proteins to cell surface to be secreted. ◼ Secretions include hormones, enzymes, antibodies and other molecules. ◼ Works with endoplasmic reticulum and ribosomes. Basic for PT1 2024-25  Golgi Apparatus L.M.: ◼ it does not appear. ◼ It can be seen as an unstained area (negative Golgi image) in protein secreting cells which have deeply basophilic cytoplasm. ◼ In (Ag)-stained sections: brown network of fibrils. Basic for PT1 2024-25  Golgi Apparatus E.M.. It consists of: ◼ Several membrane-bound flattened saccules, which are slightly curved, with flat centers and dilated ends. ◼ They are interconnected and arranged above each other forming stacks. ◼ Each stalk has 2 faces: ❑ The entry face (Convex, Cis face): receives transfer vesicles from rER. ❑ The exit face (Concave, Trans face): from which secretory vesicles arise. Basic for PT1 2024-25 Functions: 1. Modification of proteins delivered from the rER by addition of carbohydrates and sulphates. 2. Concentration and packaging of these large molecules 3. Synthesis of lysosomes & secretory vesicles. 4. Maintenance and renewal of cell membrane. Basic for PT1 2024-25 Lysosomes ◼ Recycling Center ◼ Recycle cellular debris ◼ Membrane bound organelle containing a variety of enzymes. ◼ Help digest food particles, nutrients, foreign and dead materials. Basic for PT1 2024-25 Origin: Lysosomes contain hydrolytic enzymes (synthesized in the rER ) then -------- Golgi apparatus for concentration and packing. Site : abundant in phagocytic cells as in macrophages. L.M.: histochemical stains that detect acid phosphatase enzyme. E.M.: (I) Primary lysosomes: Appear as homogenous vesicles. (II) Secondary lysosomes: Appear as heterogeneous vesicles Basic for PT1 2024-25 Types of secondary lysosomes: 1. Phagolysosome (heterolysosome): a 1ry lysosome + a phagocytic vesicle. 2. Multivesicular body: a 1ry lysosome + a pinocytic vesicle. 3. Autolysosome: a 1ry lysosome + an autophagic vesicle (vesicle containing old organelles e.g mitochondria). * The digested nutrients diffuse to cytoplasm, while undigested material is retained within vesicles called Residual bodies. Basic for PT1 2024-25 Functions: 1.Digestion of materials ingested by endocytosis (nutrients, bacteria and viruses). 2.Breakdown of old cellular organelles.. 3.Fertilization by helping the sperm to penetrate the ovum. 4.Post-mortem autolysis by digestion of the whole cell after death Basic for PT1 2024-25  Mitochondrion ◼ Double Membranous ◼ It’s the size of a bacterium ◼ Contains its own DNA; mDNA ◼ Responsible for respiration and energy production in the cell (produces high energy compound ATP) Basic for PT1 2024-25  Mitochondria ◼ ◼ Number: more numerous in cells with high energy requirement e.g. muscle cells, liver, heart and sperm cells. ◼ L.M.: as rods, granules or filaments when stained with Janus green (appear green). E.M.: is oval or rounded vesicles surrounded by 2 membranes:- The outer membrane is smooth, The inner membrane forms incomplete shelves (cristae) which increase its surface area. The space in-between is called inter-membranous space. Basic for PT1 2024-25 - The matrix contains :- (1) Enzymes that synthesize ATP via the Krebs cycle. (2) Matrix granules rich in Ca+2 (regulate the activity of enzymes). (3) DNA and RNA. Basic for PT1 2024-25 Functions : 1- Cell respiration and production of ATP. ATP is the primary source of cell energy (power house of the cell). 2- They can form proteins for themselves and can divide (self replication) as they have their own DNA and RNA. Basic for PT1 2024-25 ◼ Mescher AL (2018): Junqueira’s basic Histology Text and Atlas 14th edition ◼ https://youtu.be/fJfTDc3WzQ8?feature=shared ◼ https://youtu.be/ufCiGz75DAk?feature=shared ◼ https://youtu.be/XUM5GMeX3qk?feature=shared Basic for PT1 2024-25 Next Types of Tissues Basic for PT1 2024-25 Basic for PT1 2024-25  B. Non-Membranous Organelles ◼ Organelles that are not bounded by a membrane are solid structures that are not filled with fluid, so they do not need a membrane. ◼ Non-membranous organelles are not surrounded by plasma membranes. Basic for PT1 2024-25 Ribosomes ◼ Small non-membrane bound organelles. ◼ Contain two subunits ◼ Site of protein synthesis. ◼ Protein factory of the cell ◼ Either free floating or attached to the Endoplasmic Reticulum. Basic for PT1 2024-25  Protein synthesis ◼ Ribosome are responsible for making proteins. Basic for PT1 2024-25  Protein synthesis Each ribosome made up of two subunits. These two subunits lock around the messenger RNA and then travel along the length of the messenger RNA to read it. Then ,Protein synthesized by translating the genetic code into a specified string of amino acids, which grow into long chains that fold to form proteins. Basic for PT1 2024-25 Basic for PT1 2024-25  Cytoskeleton http://ccaoscience.files.wordpress.com/2011/04/cytoskeleton.jpg ◼ Maintain cell shape and motility. ◼ Organized network of three primary protein filaments: 1. Microtubules: 2. Actin fibers (microfilaments) 3. intermediate fibers Basic for PT1 2024-25  The cytoskeleton has three different types of protein elements ◼ Microfilaments (actin filaments). Microfilaments are often associated with myosin. They provide rigidity and shape to the cell and facilitate cellular movements ◼ Intermediate filaments bear tension and anchor the nucleus and other organelles in place ◼ Microtubules. help the cell resist compression, serve as tracks for motor proteins that move vesicles through the cell, and pull replicated chromosomes to opposite ends of a dividing cell. Basic for PT1 2024-25 Basic for PT1 2024-25 Nucleus ◼ The nucleus is found in the middle of the cells, and it contains DNA arranged in chromosomes. ◼ It is surrounded by the nuclear envelope, a double nuclear membrane (outer and inner), which separates the nucleus from the cytoplasm. Basic for PT1 2024-25  Compnent of nucleus: ◼ Nuclear Envelope ◼ Nucleoplasm ◼ Nucleolus ◼ Chromatin Basic for PT1 2024-25  Nuclear Membrane(envelope) : ◼ The nuclear membrane serves to separate the chromosomes from the cell's cytoplasm and other contents. ◼ An array of small holes or pores in the nuclear membrane permits the selective passage of certain materials, such as nucleic acids and proteins, between the nucleus and cytoplasm. Basic for PT1 2024-25  Nucleoplasm ◼ The nucleoplasm is a gel-like substance inside the nucleus of a cell. ◼ The primary components of the nucleoplasm are chromatin, fibrils, water, RNA and enzymes. ◼ The nucleoplasm is involved in cellular activities such as DNA replication and repair, RNA transcription, cell division, and protein synthesis. Basic for PT1 2024-25  Nucleoplasm The function of the nucleoplasm is to provide structural support for the chromatin in the form of a gel-like environment. This allows for the free diffusion of enzymes required in DNA replication and RNA transcription to take place throughout the nucleoplasm. Basic for PT1 2024-25  Nucleolus ◼ Ribosome factory ◼ Large prominent structure ◼ Doesn’t have membrane ◼ Most cells have 2 or more ◼ Direct synthesis of RNA Basic for PT1 2024-25  Nucleolus Function: ◼ Site of transcription ◼ Assemblage of ribosomes ◼ Synthesis of ribosomes ◼ Synthesis of RNA Basic for PT1 2024-25  Chromatin ◼ Chromatin refers to a mixture of DNA and proteins that form the chromosomes found in the cells of humans and other higher organisms Basic for PT1 2024-25 Chromosome: Function: ◼ It controls the activities of cell ◼ Information in the form of genes is located in chromosomes. ◼ Control inheritance and metabolism. Basic for PT1 2024-25 Questions Basic for PT1 2024-25  Types of Tissues (epithelial tissue) Prof. Dr. Marwa G.A. Hegazy  L.O. (Lecture 2) Objective 2 – The student will be able to: Identify four primary types of tissues in human body (epithelial, connective, muscle, nervous)and describe their primary function. Identify types of epithelium (simple, stratified). Discuss different types of connective tissue (loose, dense, adipose, cartilage, bone, blood)and describe their characteristics and functions.  Group of cells of the same type form a larger structure called a tissue (e.g. – skin, muscle). Multiple tissues can form an organ (e.g. – eye, kidney). This variation among cell groups is known as differentiation.  Types of Tissues 1) Epithelium (covering) 2) Connective (support) 3) Muscle (movement) 4) Nervous (control) Types of tissues Characteristics (Traits): Sheets of cells closely attached to each other forming a protective barrier. Specialized contacts/cell junctions Polarity : oAlways has one free (apical) surface open to outside the body or inside (cavity) an internal organ. oAlways had one fixed (basal) section attached to underlying connective tissue. Avascularity: o Has no blood vessels but can soak up nutrients from blood vessels in connective tissue underneath. Innervated : oCan have lots of nerves in it. Very good at regenerating (fixing itself). i.e. sunburn, skinned knee. E.g. skin, lining of gut, mucous membranes  Function of Epithelial Tissue ◼ Protection ❑Skin protects from sunlight & bacteria & physical damage. ◼ Absorption ❑Lining of small intestine, absorbing nutrients into blood ◼ Filtration ❑Lining of Kidney tubules filtering wastes from blood plasma ◼ Secretion ❑Form Different glands, produce, oil, digestive enzymes and mucus  Classification of epithelia According to thickness – “simple” - one cell layer – “stratified” – more than one layer of cells (which are named according to the shape of the cells in the apical layer) According to shape – “squamous” – wider than tall – “cuboidal” – as tall as wide – “columnar” - taller than wide  (Absorption and filtration) Protection where diffusion is important where tissues are involved in secretion and absorption: larger cells because of the machinery of production, packaging, and energy requirements  Features of Apical Surface of Epithelium  Microvilli: (ex) in small intestine ▪ Finger-like extensions of the plasma membrane of apical epithelial cell ◼ Increase surface area for absorption  Cilia: (ex) respiratory tubes ◼ Whip-like, motile extensions ◼ Moves mucus, etc. over epithelial surface 1-way  Flagella: (ex) spermatoza ◼ Extra long cilia ◼ Moves cell  Features of the Basal Surface of Epithelium Basal lamina: supportive sheet between epithelium and underlying connective tissue – Selective filter Basement membrane = basal lamina plus underlying reticular fiber layer – Attaches epithelium to connective tissue below Sometimes the two are used interchangeably  Features of Lateral Surface of Epithelium Cells are connected to neighboring cells via: – Proteins-link cells together, interdigitate – Contour of cells-wavy contour fits together – Cell Junctions Desmosomes Tight Junctions Gap junction  JUNCTIONS ◼Anchoring Junctions (adherens junctions) and desmosomes): oProvides adhesion of one cell to its neighbors, cell-to-cell adherence ◼Occluding Junctions (tight junctions): o joins cells together; seals to prevent loss of material (impermeable barrier to fluid). ◼ Communicating Junction (Gap Junctions) oconnects the cytoplasm of two cells, which allows various molecules and ions to pass freely between cells  Pop Quiz Name the Epithelial Feature! 3 Cilia →3 1 2 Tight →1 junction Microvilli →2 Basement →4 membrane 4  Surface Epithelium Simple epithelium: a single Stratified epithelium: two or layer of cells, resting on a more cell layers. It is classified according basement membrane. 1-Simple squamous to the shape of the superficial cells 2- Simple cubical 1-Stratified squamous: (Keratinized 3- Simple columnar / ciliated or non-Keratinized). 4-Pseudstratified columnar - ciliated 2-Transitional epithelium  Simple Squamous Epithelium ◼ Structure Single Layer of flattened cells Disc shape central nuclei ◼ Function Absorption, and filtration Not effective protection – single layer of cells. ◼ Location Walls of capillaries, air sacs in lungs Form serous membranes in body cavity  Simple Cuboidal Epithelium ◼ Structure Single layer of cube shaped cells Large spherical central nuclei ◼ Function Secretion and transportation in glands, filtration in kidneys ◼ Location ducts (pancreas & salivary), kidney tubules, covers ovaries  Simple Columnar Epithelium ◼ Structure Elongated layer of cells with round or oval nuclei at same level ◼ Function Absorption, Protection & Secretion When open to body cavities – called mucous membranes ◼ Special Features Microvilli, bumpy extension of apical surface, increase surface area and absorption rate. Goblet cells, single cell glands, produce protective mucus. ◼ Location Linings of entire digestive tract, fallopian tubes, uterus (ciliated)  Pseudostratified Epithelium ◼ Structure Cilia Irregularly shaped cells with nuclei at different levels – appear stratified, but aren’t. Some of cell not reaching the surface ◼ Function Absorption and Secretion Goblet cells produce mucus Cilia (larger than microvilli) sweep mucus ◼ Location Basement Respiratory Linings & Reproductive Membrane tract  Stratified Squamous Epithelium ◼ Structure Many layers, stronger than simple Basal cell is cuboidal or columnar and surface cell are squamous (flattened) ◼ Function Protection Keratin (Superficial cells gradually die &form keratin) (protein) is accumulated in older cells near the surface – waterproofs and toughens skin. ◼ Location Skin (keratinized), dry exposed surfaces Vagina, Oral cavity, Esophagus , Cornea (Non keratinized) wet exposed surfaces  Stratified cuboidal ◼Generally 2 layers of cube like cell ◼protection Male urethra Sweat glands Stratified Cuboidal (layers of cuboidal only)  Stratified columnar ◼Several cell layers ◼Basal cell cuboidal, superficial cell elongated and columnar ◼The cells function in secretion and protection Epiglottis Conjunctiva of the eye Pharynx Anal mucous membrane  Simple cuboidal Pop Quiz!! E Can You Identify the columner epithelium Classes of Epithelium? D Simple squamous Pseudostratified columnar A B Stratified Squamous Epithelium C Connective Tissue Without it you’d fall apart.  CONNECTIVE TISSUE  It contains sparsely packed cells scattered throughout an extracellular matrix  The matrix consists of fibers in a liquid, jellylike, or solid foundation  Connective tissue function: Binding and support Protection Insulation Transportation  Connective tissues characteristics: › Mesenchyme as their common tissue of origin (embryonic tissue; mesoderm). › Varying degrees of vascularity and most also have nervous innervation › Nonliving extracellular matrix, consisting of ground substance and fibers proteins Connective Tissue Consists of three basic elements: Cells, fibers and Extra-cellular matrix  C.T. Components Cells Fibers Matrix Soft---C.T. proper Rubbery--Cartilage Solid---Bone Fluid---Blood  CELLS  Fixed: resident population of cells that have developed and remain in place within the CT, they are stable and long-lived. ❑ Fibroblasts ❑ Adipose cells ❑ Pericytes ❑ Mast cells ❑ Macrophages  Transient: free or wandering, originate in the BM and circulates in the blood stream ❑ Plasma cells ❑ Lymphocytes ❑ Neutrophils ❑ Eosinophils ❑ Basophils ❑ Monocytes ❑ Macrophages  Matrix Cells Cells in connective tissue make and maintain the ground substance and fibers. Each type of conn. Tissue have immature and mature forms of these cells. Immature cells have suffix “-blast” – actively produce matrix (Active state). Mature cells have suffix “-cyte” – maintain health of matrix, reverting to blasts to regenerate matrix after injury. – Fibroblasts – make conn. Tissue/fibers – Chondroblasts – make cartilage, – Osteoblasts – make bone – Hematopoeitic stem cells – make blood  Matrix Fibers Fibers are embedded in ground substance to add strength/flexibility 1.Collagen Fibers: Large fibers made of the protein collagen and are typically the most abundant fibers. Promote tissue flexibility. They are tough and provides high tensile strength. 2.Elastic Fibers: Intermediate fibers made of the protein elastin. Branching fibers that allow for stretch and recoil. 3.Reticular Fibers: Small delicate, branched fibers that have same chemical composition of collagen. Forms structural framework for organs i.e. join connective tissue to adjacent tissues such as spleen and lymph nodes.  CLASSIFICATION OF CONNECTIVE TISSUE 1. True Connective Tissue/CTP a. Loose Connective Tissue b. Dense Connective Tissue 2. Supportive Connective Tissue a. Cartilage b. Bone 3. Liquid Connective Tissue a. Blood  CLASSIFICATION OF CONNECTIVE TISSUE 1. True Connective Tissue/CTP a. Loose Connective Tissue b. Dense Connective Tissue 2. Specialized Connective Tissue a. Cartilage b. Bone c. Blood Connective Tissue  Types of C.T. proper Loose Dense Abundance of ground substance Cells &fibers are scattered Abundance of fibers with fewer cells than in the loose type -Loose areolar C.T -White fibrous -Adipose C.T -Yellow elastic -Reticular C.T -Mucoid C.T  Loose (Areolar) C.T Reticular C.T Most common type Cells All types of cells Reticular cells Fibers All types of fibers (collagen) Fine network of reticular More abundant matrix fibers. Matri Moderate amount x ❑ Potential cavities which can ❑ Delicate type accommodate large amount of fluids and gases. ❑ Flexible and well-vascularized ❑ Everywhere in the body except the brain: ❑ Supportive frame work in ❑ Spaces between the organs. stroma of organs : spleen Sites &lymph node & liver ❑ Exchanging of nutrients to and from ❑ Supportive Functi blood vessels on ❑ Binding of structures together  Adipose C.T Structure Cell Mainly fat cells Fine network of. Collagen and elastic fibers. Fibers White adipose C.T Brown adipose C.T ❑ Fat cells are unilocular ❑ Fat cells are multilocular ❑ Less vascularity ❑ High vascularity ❑ Affected by diet and hormones ❑ Affected by hormones only. ❑ Under the skin (subcutaneous layer ) ❑ New born replaced gradually by the white ❑ Around kidney &other organs type Sites ❑ Heat insulation. ❑ Thermogenesis in newborn ❑ Storage of fat &giving the skin contour Function ❑ Support organs  White fibrous C.T Structure Cell Fibroblasts Fibers Collagen fibers packed into bundles. Matrix Minimal amount (more vascularity). -Very dense type (white in fresh section). Characters -Resistant and less flexible. Regular Irregular Regularly arranged collagen bundles irregularly arranged collagen bundles with rows of fibroblasts in between with scattered fibroblasts Sites Tendons &Cornea Ligaments & Sclera of eye Capsule of organs -Withstand stretch in one directions -Withstand stretch in all directions Function  Yellow elastic C.T Structure Cell Fibroblasts Fibers Regular parallel elastic fibers. Matrix Small amount. -Dense type (yellow in fresh section). -Great elastic power. Characters ❑ Aorta and large arteries Sites ❑ Trachea ❑ Some ligaments -Great elastic power Function Connective Tissue: Hyaline Cartilage Figure 4.8g  Connective Tissue: Fibrocartilage Cartilage Matrix similar to hyaline cartilage but less firm with thick collagen fibers Provides tensile strength and absorbs compression shock Found in intervertebral discs, the pubic symphysis, and in discs of the knee joint Figure 4.8i  Connective Tissue: Elastic Cartilage Similar to hyaline cartilage but with more elastic fibers Maintains shape and structure while allowing flexibility Supports external ear (pinna) and the epiglottis Figure 4.8h Connective Tissue: Bone (Osseous Tissue) Figure 4.8j Connective Tissue: Blood Figure 4.8k  Connective Tissue Collagenous fiber Loose Chondrocytes connective Cartilage tissue 120 µm 100 µm Elastic fiber Chondroitin sulfate Nuclei Fat droplets Fibrous connective Adipose tissue 150 µm tissue 30 µm Osteon White blood cells Bone Blood 55 µm 700 µm Central canal Plasma Red blood cells  Mescher AL (2018): Junqueira’s basic Histology Text and Atlas 14th edition  NEXT Lymphatic System The Vascular system Prof. Dr. Marwa G.A. Hegazy Dr. Heba Afifi  Learning Outcomes: Identify the major components of the vascular system, including arteries, veins, and capillaries, and describe their unique characteristics and functions. Understand the structure and function of the three layers of blood vessels (tunica intima, tunica media, and tunica adventitia) and their roles in maintaining vascular integrity and blood flow.  Blood Vessels They include: Arteries: Large arteries, medium sized arteries & arterioles. Veins: Large veins, medium sized veins & venules. Arterio-Venous Connections: Blood capillaries.  Arteries The walls of arteries are thicker than that of veins to withstand pulsatile flow and higher blood pressures. As arteries become smaller, wall thickness gradually decreases but the ratio of wall thickness to lumen diameter increases (i.e. relative lumen size decreases). Arteries are divided into three types according to size and function. 1. large elastic arteries (aorta and pulmonary arteries): the media is abundant in elastic fibers that allow it to expand with systole and recoil during diastole, thereby propelling blood forward  medium-sized muscular arteries (other aortic branches, e.g. coronary and renal arteries): the media is abundant in smooth muscle cells that vasoconstrict or vasodilate, thereby controlling lumen diameter and regional blood flow.  small arteries and arterioles (in the substance of organs and tissues): the media is abundant in smooth muscle cells that vasoconstrict or vasodilate; in vessels of this size, smooth muscle contraction causes dramatic changes in lumen diameter, thereby controlling systemic blood pressure as well as regional blood flow.  Medium-Sized Artery &Vein Simple squamous endotheliu Tunica m intima Internal Elastic lamina Smooth muscle Tunica media Tunica Elastic adventitia fibres  Medium-sized Artery Medium-sized Vein 1-Thick wall and narrow lumen 1-Thin wall and wide lumen 2. The lumen is rounded, doesn't collapse 2-The lumen collapses after death after death 3. It has no valves 3-It has valves 4. The lumen contains no blood after 4-The lumen contains blood after death death 5. T. Intima is thick, folded, rich in elastic 5-T. Intima is thin, not folded, poor in fibers, has a clear internal elastic elastic fibers, has no internal elastic lamina lamina 6-T. Media is thick, made of smooth 6. T. media is thin, made of smooth muscles and elastic fibers muscles, poor in elastic fibers 7. External elastic lamina may be present 7. It has no external elastic lamina in between the media & adventitia 8-T. Adventitia is thin, rich in elastic fiber 8. T. Adventitia is thick, rich in collagen fibers  Blood capillaries are vascular networks inside human body. Formed of a single layer of simple squamous epith. Resting on a basal lamina and rolls up forming a tube. Types of capillaries: 1. Continuous 2. Fenestrated 3. sinusoidal  Continous Fenestrated Sinusoidal capill. capill. capill. Large ,irregular Small ,regular Small ,regular Has pores without diaphragm Continuous Has pores covered epith.& basal by diaphragm Site: lamina Site: liver, bone Site: all over the marrow & spleen intestine, body. endocrine glands.  General structure of blood vessels: It is formed of 3 layers from inside outwards: 1- Tunica Intima: Site: the innermost layer. Function: It is in contact with blood stream. It provides a smooth surface for blood flow It is formed of: 1. Endothelium: simple squamous epith. 2. Subendothelium: loose C.T. to support the endothelium. 3. Internal elastic lamina: a layer of elastic fibers.  2-Tunica Media: Site: the middle layer. Function: It regulates blood flow by muscle contraction. It is formed of: 1. Circularly arranged smooth muscle fibers. 2. Variable amounts of elastic fibers. 3. Its outer layer is limited with external elastic lamina. 3-Tunica Adventitia: Site: The outermost layer. Function: 1. connects the blood vessels to the surrounding tissues 2. prevents over-distension of the vessel. formed of: loose C.T. 1. ( ++++ collagen fibers , some elastic fibers and some C.T. cells). 2. Contains nerves, lymphatics & vasa vasorum  Vasa Vasorum: They are small arteries (blood vessel of the blood vessel) Site: present mainly in the adventitia of large blood vessels e.g. aorta and large veins). Funct: nourish the outer part of the vessel wall. * Lymphatic System Prof. Dr. Marwa G.A. Hegazy ILO’s (Lecture3) *Objective 3 – The student will be able to: Understand the structure and function of the lymphatic system, including lymphatic vessels, lymph nodes, and lymphoid organs, and describe their roles in immune function.  *Lymphatic System * Lymphatic system is a network of vessels through which lymph drains from the tissues into the blood. *LYMPH - an extracellular fluid (ECF) similar to plasma; ECF is found in several places in the body: body tissues (ECF = interstitial fluid), blood (ECF = plasma), and lymphatic vessels (ECF = lymph) * our lymphatic system is a group of organs, vessels and tissues that protect you from infection and keep a healthy balance of fluids throughout your body.  *Lymphatic System: Pathways *Lymphatic capillaries *Extend into interstitial spaces *Permeable, thin walls pick up fluid, which become lymph *Delivers lymph to lymphatic vessels through afferent lymphatic vessels *Lymphatic vessels *Deliver lymph to lymph nodes *Cells in nodes can remove pathogens from lymph and start an immune response *Leaves nodes through them too. *Lymphatic System: Pathways (cont.) *Lymphatic trunks *Receive lymph from efferent lymphatic vessels *Deliver it to lymphatic ducts *Lymphatic collecting ducts *Thoracic duct *Left side of head and neck, left arm, left side of thorax, entire abdominopelvic area, and both legs *Right lymphatic duct *Right side of head and neck, right arm, and right side of chest  *LYMPH VESSELS (LYMPHATICS) some passes The When excess to blood tissue Lymph circulation surroundings reach the fluid vessels as tissue capillaries fluid (lymph) They are formed of : 1. Lymphatic capillaries. 2. Small and medium sized lymphatic vessels 3. Lymphatic duct Basic for physiotherapy 1 (Lecture2) Lymph node Primary Secondary Sites where B- & T- lymphocytes formed Sites where immune response occurs and and mature lymphocytes perform their function Bone marrow Lymph node Thymus Spleen Tonsils Payer's patches Appendix *LYPHATIC ORGANS (Immunological function).  * Functions of the Lymphatic System *Lymphatic vessels drain excess interstitial fluid from tissue spaces (distributed all over the body except nervous system has its own circulation CSF ). *Lymphatic vessels transport the lipids and lipid-soluble vitamins (A,D, E, K) absorbed by the GI tract to the blood. *Lymphatic tissue initiates highly specific responses directed against particular microbes or abnormal cells. Lymphocytes can recognize foreign cells, microbes, toxins and cancer cells.  * Tissue Fluid and Lymph *Lymph moves in response to: ✓contraction of surrounding skeletal muscles (veins return blood to the heart using a similar mechanism); like veins, lymph vessels have valves to keep the fluid moving in one direction ✓contraction of smooth muscle in wall of the lymphatic vessel ✓pressure changes in the thoracic cavity during respiration *Interstitial fluid *Fluid in spaces between cells that has leaked from blood capillaries and has not been picked up by body cells *High in nutrients, oxygen, and small proteins *Becomes lymph * Pushed through lymphatic vessels by squeezing action of neighboring skeletal muscles and breathing movement *References * https://youtu.be/cCPyWFK0IKs?feature=shared * https://youtu.be/o0-1OknbO3M?feature=shared  NEXT BONE TISSUE Bone Tissue Prof. Dr. Marwa Hegazy  LO’s (Lecture 4) Objective 4 – The student will be able to: ◼ Identify the different types of bone tissue, including compact and spongy bone, and understand their unique structural and functional characteristics. ◼ Understand the structure and function of osteocytes, osteoblasts, and osteoclasts, the primary cells of bone tissue, and their roles in bone formation and remodelling. ◼ Describe the process of bone growth and development, including endochondral ossification and intramembranous ossification, and understand the factors that influence bone growth and remodelling.  Function of Bones ◼ The adult skeleton has 206 bones Bone is a specialized type of CT., Matrix is hard& calcified, Highly vascular Bones perform several important functions: ◼ Support :Hard framework that supports the body and internal organs. ◼ Protection: Fused bones provide a brain case that protects this vital tissue, Spinal cord is surrounded by vertebrae, Rib cage protects vital organs ◼ Movement :Skeletal muscle attached to bones use the bones as levers to move the body. ◼ Mineral storage: Bone serves as a mineral reservoir; Phosphate and calcium ions can be released into the blood steam for distribution. ◼ Blood cell formation: The majority of hematopoiesis occurs within the marrow cavities of the long bones.  Structure of Bone ◼ Bone consists of cells and extracellular matrix. ✓ Matrix: ❑ 70% mineral ❑ 22% protein ❑ 8% water ✓ Cells: ◼ Osteogenic ◼ Osteoblast ◼ Osteocyte ◼ Osteoclast ◼ Osteogenic (Bone lining cells): inactive osteoblasts. They cover all of the available bone surface and function as a barrier for certain ions. ◼ Osteoblasts: Responsible for osteogenesis – create bone tissue, mature into osteocytes, make and deposit components of bone extracellular matrix, collagen secretors. Osteoprogenitor cells: Derived from mesenchymal cells, can undergo mitosis, Mature into osteoblasts, found on inner surface of periosteum and endosteum, (bud cells) ◼ Osteoclasts: Derived from embryological WBCs, secrete enzymes for osteolysis – resorb/break down bone tissue for remodeling, necessary for calcium homeostasis, found on bone surface, ◼ Osteocytes: “watcher cells” Sit in bone and monitor its current status, derived form osteoblasts do not secrete matrix material, cellular duties include exchange of nutrients and waste with blood (mature cells) Cells of Bone Tissue Anatomical types: (according to shape) 1-Long bones 2- Short bones 3- Flat bones 4- Irregular bones Histological types: (according to structure) 1- Compact (regular) 2- Spongy (irregular) bone. Anatomical Classification of Bones  Anatomical Classification of Bones ◼ Long Bones- long and slender (forearm, thigh ,leg (A shaft with 2 heads)). ◼ Short Bones- Short and boxy cube like (carpal bones, tarsal bones). ◼ Flat Bones- thin, flattened, usually curved. (Most bones of Skull, ribs, sternum. ◼ Irregular Bones- Complicated shapes (vertebrae)  Gross Anatomy of Long Bone ◼ Landmarks on a typical long bone ◼ Diaphysis ◼ Epiphysis ◼ Membranes Periosteum Endosteum Diaphysis ◼ Long tubular diaphysis is the shaft of the bone ◼ Collar of compact bone surrounds a central medullary or marrow cavity ◼ In adults, cavity contains fat Epiphysis ◼ The epiphyses are the ends of the bone ◼ The joint surface of the epiphysis is covered with articular cartilage ◼ Epiphyseal line separate diaphysis and epiphysis Blood Vessels ◼ Unlike cartilage, bone is well vascularized ◼ Nutrient arteries serve the diaphysis ◼ The nutrient artery runs inward to supply the bone marrow and the spongy bony Medullary cavity ◼ The interior of all bones consists largely of spongy bone ◼ The very center of the bone is an open cavity or marrow cavity ◼ The cavity is filled with red marrow produces blood cells yellow marrow is adipose. Membranes ◼ Periosteum covers outer bone surface ◼ Consists of dense irregular connective tissue & osteoblasts ◼ Contain nerve fiber, blood and lymph vessels secured by Sharpey’s fibers ◼ Endosteum covers internal bone surfaces Gross Anatomy of Short, Irregular and Flat Bones ◼ Bones consist of thin layers of compact bones over spongy bone ◼ No shaft, epiphysis or marrow cavity ◼ Spongy area between is a diploe ◼ Flat sandwich of bone  Hematopoietic Tissue ◼ The hematopoietic tissue, red marrow, is typically found within the cavities of spongy bone of long bones and in the diploe of flat bones ◼ These cavities are referred to as red marrow cavities ◼ In infants the medullary cavity and all areas of spongy bone contain red bone marrow ◼ In adults the medullary cavity contains fat that extends into the epiphysis and there is little red marrow present in spongy bone cavities ◼ Blood cell production occurs only in the head of the femur and humerous ◼ Most blood cell production occurs in the diploe areas of the sternum and hip ◼ Yellow marrow can revert to Red marrow if the person becomes very anemic  Histological Classification of Bones 1- Compact Bone  1. Compact Bone ◼ Sites 1. Shafts of long bones 2. Covering over the surface of spongy bone. ◼ It is formed of: 1. Periosteum 2. Bone lamellae 3. Haversian Systems (osteons ) 4. Endosteum Compact bone Compact bone An Osteon ◼ The structural units of compact bone. ◼ They are cylindrical structures running parallel to the long axis of bone. ◼ Formed of: 1. Haversian canal: Central vascular canal contains blood vessels, nerves. 2. Bone lamellae: 3. Osteocytes inside their lacunae  Compact bone ◼ Osteocytes occupy small cavities or lacunae at the junctions of lamellae ◼ Fine canals called canaliculi connect the lacunae to each other and to the central canal ◼ Canaliculi tie all the osteocytes in an osteon together ◼ Interstitial lamellae represent older osteons that have been partially removed during tissue remodeling 2. Spongy bone (cancellous)  Spongy Bone Sites: flat & irregular bones. Structure: Anastomosing bone trabeculae Multiple marrow cavities Osteocytes in their lacunae No Haversian systems.  2. Spongy bone (cancellous) ◼ Latticework of thin plates of bone called trabeculae oriented along lines of stress. Function as struts of bone ◼ Spaces in between these struts are filled with red marrow where blood cells develop. ◼ It is light and supports and protects the red bone marrow. ◼ Found in short, flat, and irregular bones, and the epiphyses of long bones such as the hipbones, sternum, sides of skull, and ribs. ◼ Trabeculae contain irregularly arranged lamallae and osteo-cytes interconnected by canaliculi ◼ No osteons present.  BONE FORMATION ◼ All embryonic connective tissue begins as mesenchyme. ◼ Bone formation is termed osteogenesis or ossification and begins when mesenchymal cells provide the template for subsequent ossification. ◼ In the developing embryo the process leads to the formation of the bony skeleton. ◼ Bone growth continues until adulthood as the individual increases in size BONE OSSIFICATION 1- INTRAMEMBRANOUS OSSIFICATION  Site: the flat bones of the skull.  It starts in a membrane of CT & ends by formation of spongy bone. 2-INTRACARTILAGENOUS OSSIFICATION  Site: Long ,short & irregular bones.  It means replacement of the cartilage model by cartilage or spongy bone.  Intramembranous Ossification 1. Formation of an ossification center in the fibrous membrane Centrally located mesenchymal cells cluster and differentiate into osteoblasts, forming the ossification center Intramembranous Ossification 2 Formation of the bone matrix within the fibrous membrane Osteoblasts begin to secrete osteoid; it is mineralized within a few days Trapped osteoblasts become osteocytes  Intramembranous Ossification 3 Formation of the woven bone and the periosteum Accumulating osteoid forms a network which encloses local blood vessels Vascularized mesenchyme forms on the external face of woven bone to become periosteum  Intramembranous Ossification 4 Bone collar of compact bone forms Trabeculae just deep to the periosteum thicken, forming a woven collar which is later replaced with mature lamellar bone Spongy bone persists internally and its vascular tissue becomes red marrow Intramembranous Ossification  Endochondral Ossification 1. Formation of a bone collar (dense bone) around hyaline cartilage model Osteoblasts of the new periosteum secrete osteoid against the hyaline cartilage along the diaphysis  Endochondral Ossification 2. Cartilage in the center of the diaphysis calcifies Calcification of cartilage blocks nutrients and chondrocytes die Matrix deteriorates and cavities develop Bones stabilized by collar; growth occurs at epiphysis  Endochondral Ossification 3 Invasion of the internal cavities by the periosteal bud and spongy bone. Bud contains nutrient artery & vein, lymphatics, nerve fibers, red marrow elements, osteoblasts and osteoclasts Spongy bone forms  Endochondral Ossification 4. Formation of the medullary cavity as ossification continues Secondary ossification centers form in epiphyses Cartilage in epiphyses calcifies and deteriorates opening cavities for entry of periosteal bud  Endochondral Ossification 5. Ossification of the epiphyses Hyaline cartilage remains only at epiphyseal plates Epiphyseal plates promote growth along long axis Ossification chases cartilage formation along length of shaft Endochondrial Ossification Bone Remodeling ◼ Deposition: the biological process of laying down the bone ◼ Resorption: the biological process of removing the bone ◼ Remodeling: A basic part of bone growth involves simultaneous deposition and resorption on all inner and outer surfaces of the entire bone. It provides regional changes in shape, dimensions, and proportions. Why Does bone remodel? ◼ Bone is a living tissue. It is continuously created and re-created by the remodeling actions of osteoblasts and osteoclasts. ◼ Because the bones are constantly under changing stresses and need construction, the remodeling process allows for both the repair of damaged bones and adaptation of bone to different tangential & support stresses. It also facilitates the release of minerals to the blood. ◼ Mescher AL (2018): Junqueira’s basic Histology Text and Atlas 14 th edition ◼ https://youtu.be/0dV1Bwe2v6c?feature=shared ◼ https://youtu.be/inqWoakkiTc?feature=shared ◼ https://youtu.be/YXDyQiVepWk?si=0lXqn2l7UlnEp 4_G ◼ https://youtu.be/Vwethc4jt7U?si=ZPK0ccxG_T_LiU 28 Basic for physiotherapy 1 (Lecture 4) Muscle Tissue Function of Muscle Tissue ▪ Movement (Locomotion) ▪ Skeletal muscle - attached to skeleton ▪ Moves body by moving the bones ▪ Smooth muscle – squeezes fluids and other substances through hollow organs ▪ Maintenance of posture – enables the body to remain sitting or standing ▪ Respiration :Diaphragm and intercostals contractions ▪ Communication (Verbal and Facial) ▪ Joint stabilization ▪ Heat generation ▪ Muscle contractions produce heat (shivering) ▪ Helps maintain normal body temperature (Thermogenesis) Special functional characteristics of muscle ▪ Contractility ▪ ability of a muscle to be shorten and generate pulling force ▪ Excitability (irritability) ▪ capacity of muscle to respond to a stimulus ▪ nerve fibers cause electrical impulse to travel ▪ Extensibility ▪ muscle can be stretched back to its original length ▪ Elasticity ▪ ability of muscle to recoil to original resting length after stretched  Types of Muscle Tissue ▪ Skeletal muscle (40% of body weight, attaches to bone, skin or fascia, cells are long, cylindrical with obvious striations, striated with light & dark bands visible with scope, fibers= multinucleate cells (embryonic cells fuse), voluntary control of contraction & relaxation) ▪ Cardiac muscle (only in the wall of the heart, its function is to pump blood (involuntary control), cells are short, branched and striated in appearance, cells attached to other cardiac muscle cells at intercalated disks, one nucleus per cell) ▪ Smooth muscle (attached to hair follicles in skin, in walls of hollow organs -- blood vessels & GI, cells are short, spindle- shaped and nonstriated in appearance, one nucleus per cell, involuntary)  Anatomy of skeletal muscles Epimysium Bone Epimysium Perimysium Tendon Endomysium Muscle fiber in middle of a fascicle (b) Blood vessel Fascicle (wrapped by perimysium) Endomysium (between individual muscle fibers) Perimysium Fascicle Muscle fiber (a) ▪ Connective tissue sheaths of skeletal muscle: ▪ Epimysium: dense regular connective tissue surrounding entire muscle ▪ Perimysium: fibrous connective tissue surrounding fascicles (groups of muscle fibers) ▪ Endomysium: fine areolar connective tissue surrounding each muscle fiber  Microscopic and Functional Anatomy of Skeletal Muscle ▪ The skeletal muscle fiber ▪ Fibers are long and cylindrical ▪ Each cell formed by fusion of embryonic cells ▪ Cells are multinucleate ▪ Nuclei are peripherally located ▪ Striations result from internal structure of myofibrils ▪ Myofibrils ▪ Long rods within cytoplasm ▪ Make up 80% of the cytoplasm ▪ Are a specialized contractile organelle found in muscle tissue ▪ A long row of repeating segments called sarcomeres (functional unit of Skeletal MT) Muscle Fiber Sarcoplasmic Reticulum and T Tubules ▪ Sarcoplasmic reticulum ▪ A specialized smooth ER ▪ Interconnecting tubules surround each myofibril ▪ Some tubules form cross-channels called terminal cisternae ▪ Cisternae occur in pairs on either side of a t-tubule ▪ Contains calcium ions – released when muscle is stimulated to contract ▪ Calcium ions diffuse through cytoplasm ▪ Trigger the sliding filament mechanism ▪ T (transverse) tubules are invaginations of the sarcolemma into the center of the cell ▪ filled with extracellular fluid ▪ carry muscle action potentials down into cell ▪ Sarcolemma = muscle cell membrane ▪ Sarcoplasm filled with myofibrils & myoglobin (red-colored, oxygen-binding protein) ▪ Mitochondria lie in rows throughout the cell ▪ near the muscle proteins that use ATP during contraction Sarcoplasmic Reticulum and T Tubules Sarcomere ▪ Basic unit of contraction of skeletal muscle ▪ Z disc (Z line) – boundaries of each sarcomere ▪ Thin (actin) filaments – extend from Z disc toward the center of the sarcomere ▪ Thick (myosin) filaments – located in the center of the sarcomere ▪ Overlap inner ends of the thin filaments ▪ Contain ATPase enzymes ▪ A bands – full length of the thick filament ▪ Includes inner end of thin filaments ▪ H zone – center part of A band where no thin filaments occur. ▪ M line – in center of H zone ▪ Contains tiny rods that hold thick filaments together ▪ I band – region with only thin filaments ▪ Lies within two adjacent sarcomeres Sarcomere The Proteins of Muscle ▪ Myofibrils are built of 3 kinds of protein ▪ contractile proteins ▪ myosin and actin ▪ regulatory proteins which turn contraction on & off ▪ troponin and tropomyosin ▪ structural proteins which provide proper alignment, elasticity and extensibility ▪ titin, myomesin, nebulin and dystrophin Actin and Myosin Filaments actin myosin Myosin (Thick) Filament Actin (Thin) Filament  1. Innervation of Skeletal Muscle (Excitation) ▪ Each skeletal muscle is supplied by a nerve, artery and two veins. ▪ Each motor neuron supplies multiple muscle cells (neuromuscular junction NMJ) ▪ Neuromuscular junction is the point where nerve ending and muscle fiber meet ▪ Each muscle cell is supplied by one motor neuron terminal branch and is in contact with one or two capillaries. ▪ nerve fibers & capillaries are found in the endomysium between individual cells  Biology 100 motor neurons Human Biology spinal cord neuromuscular junctions Motor Unit muscle fibers muscle bundle  2. Events Occurring After a Nerve Signal (ECC) ▪ Arrival of nerve impulse at nerve terminal causes release of ACh from synaptic vesicles ▪ ACh binds to receptors on muscle motor end plate opening the gated ion channels so that Na+ can rush into the muscle cell ▪ Inside of muscle cell becomes more positive, triggering a muscle action potential that travels over sarcolemma and down the transverse tubules (T-tubules) ▪ The release of Ca+2 from the SR into the sarcoplasm is triggered and the muscle cell will shorten & generate force ▪ Ca+2 binds to troponin & causes troponin-tropomyosin complex to move & reveal myosin binding sites on actin--the contraction cycle begins ▪ Acetylcholinesterase breaks down the ACh attached to the receptors on the motor end plate so the muscle action potential will cease and the muscle cell will relax. Stimulation of Skeletal Muscle EM of Myofibrils  3. Contraction Cycle ▪ Repeating sequence of events that cause the thick & thin filaments to move past each other. ▪ 4 steps to contraction cycle ▪ ATP hydrolysis. (ATP released P & ADP & energy) and myosin heads are activated by ATP ▪ Attachment of activated heads of myosin to actin to form cross bridges & pull. ▪ Thin filaments slide past the thick filaments (power stroke) ▪ ATP binds to myosin head and detachment of myosin from actin ▪ Cycle keeps repeating as long as there is ATP available & high Ca+2 level near thin filament 22  Contraction Cycle Steps ▪ Notice how the myosin head attaches and pulls on the thin filament with the energy released from ATP Contraction proceeds as follows: ▪ The arrival of a nerve impulse to the neuromuscular junction --- ---- depolarization of the sarcolemma of muscle fiber. ▪ Depolarization is transmitted ------- the T- tubules ------- into the depth of the muscle fiber. ▪ It stimulates the sER------ release the Ca++ into the sarcoplasm. ▪ Ca++ facilitates ------ the sliding of the actin filaments over the myosin.  4. Relaxation ▪ Acetylcholinesterase (AChE) breaks down ACh within the synaptic cleft ▪ Muscle action potential ceases ▪ Ca+2 release channels close ▪ Active transport pumps Ca+2 back into storage in the sarcoplasmic reticulum ▪ Calcium-binding protein (calsequestrin) helps hold Ca+2 in SR (Ca+2 concentration 10,000 times higher than in cytosol) ▪ Tropomyosin-troponin complex recovers binding site on the actin Tendon ligament Regular dense fibrous C.T Irregular dense fibrous C.T Connect muscle to bone Connect bone to bone Transmit muscle strength Hold structures together to bone (movement) (stable) Tear or stretch in it called Tear or stretch in it called (Strain) (Sprain) Nerve cell & skin Prof. Dr. Marwa G.A. Hegazy Dr. Heba Afifi Basic for physiotherapy 1 (Tutorial 4)  Learning outcomes:  Describe the different types of neurons, including sensory, motor, and interneurons.  Identify the different types of glial cells, including astrocytes, oligodendrocytes, and microglia, and understand their roles in supporting and protecting neurons.  Understand the structure and function of the epidermis, and its role in protecting the body from external factors.  Understand the role of Langerhans cell in the epidermis, including their function in immune response. Basic for physiotherapy 1 (Lecture2)  Functions  Sensation – senses changes in the environment: internal and external  Integration – interprets the changes (stimulus)  Response – initiates a response through: muscle contraction or glandular secretion Cells of Nervous System Neurons or nerve cells Receive stimuli and transmit action potentials Organization Cell body or soma Dendrites: Input Axons: Output Neuroglia or glial cells Support and protect neurons: hold them in place; to supply nutrients to neurons; to insulate neurons electrically; to destroy pathogens and remove dead neuron. Nerve cell (Neuron) Structural and functional unit of the nervous system Basic for physiotherapy 1 (Lecture2)  Histological structure 1)Cell body -Nucleus : pale , large, spherical -Cytoplasm: ▪ rER and ribosomes (Nissil granules) ▪ G.A ▪ Mitochondria scattered ▪ No centrioles ▪ Microtubules &Neurofilaments Basic for physiotherapy 1 (Tutorial 4)  2)processes -Dendrites: Multiple, carry stimulus to neuron -Axon: Single, carry stimulus away from neuron Basic for physiotherapy 1 (Tutorial 5) 3) Myelin Sheath A white, multi layered, fatty covering for some nerve processes. Arranged in segments, separated by Nodes of Ranvier (enables salutatory conduction). Insulation of nerve process, Increased speed of conduction Neurilemma – outer layer of myelin sheath – essential for regeneration Basic for physiotherapy 1 (Lecture2)  Types of Neurons  Functional classification  Sensory or afferent: Action potentials toward CNS  Motor or efferent: Action potentials away from CNS  Interneurons or association neurons: within CNS from one neuron to another  Types of Neurons Structural Classification − Multipolar: many extensions from the cell body, common type − Bipolar: one axon and one dendrite, only found in eye, ear & nose − Unipolar (pseudounipolar) : have a short single process leaving the cell body − Anaxonic : no anatomical clues to determine axons from dendrites, functions unknown  Glial cells (Neuroglia) ❖10 times more abundant than neurons ❖Smaller than neurons ❖Surround the cell bodies and processes Basic for physiotherapy 1 (Tutorial 5)  Neuroglia of CNS  Astrocytes  Abundant, star-shaped cells  Regulate extracellular brain fluid composition  Promote tight junctions to form blood-brain barrier  Ependymal Cells  Line brain ventricles and spinal cord central canal  Help form choroid plexuses that secrete CSF  Neuroglia of CNS  Microglia  Spider-like macrophages  Dispose of debris  Oligodendrocytes  Form myelin sheaths if surround axon  Neuroglia of PNS  Schwann cells or neurolemmocytes  Wrap around portion of only one axon to form myelin sheath  Satellite cells  Surround neuron cell bodies in ganglia, provide support and nutrients  Skin ❖ A protective covering of the whole body ❖ Heaviest and largest organ Basic for physiotherapy 1 (Tutorial 5 )  Structure 1- Epidermis : keratinized stratified squamous epithelium 2- Dermis :thick C.T layer under epidermis Basic for physiotherapy 1 (Tutorial 5)  Epidermis ❖Stratum basale: single layer of columnar cells (mitotic figures) ❖stratum spinousm :4-8 layers of polyhedral cells &rounded nuclei ❖Stratum granulosum: 3-5 layers of flat cells &flat nuclei ❖Stratum lucidum: clear homogenous layer ❖Stratum corneum (Keratin): thick acidophilic layer (dead cells) Basic for physiotherapy 1 (Lecture2)  Langerhan’s cells ❖ Non keratinocytes ❖ Stellate shaped cells found between cells of stratum spinousm ❖ No melanin pigments, no keratin ❖ Skin immunity (antigen presenting cells ) Basic for physiotherapy 1 (Tutorial 5)  Types of skin Thick skin Thin skin Sites Palms and soles Rest of the body Tips &sides of fingers and toes Epidermis Thicker (thick keratin layer) Thinner (thin keratin layer) Appandeges hair present absent Sebaceous glands Arrector pili muscle Sweat gland More Less Basic for physiotherapy 1 (Tutorial 5) Basic for physiotherapy 1 (Tutorial 5 )  Keratinocytes Keratinocytes are the main cellular components of the epidermis. They release very little extracellular matrix so that the plasma membrane of adjoining keratinocytes are very close to one another. Basic for physiotherapy 1 (Lecture2)  Function of Keratinocytes The primary function of keratinocytes is the formation of a barrier against environmental damage by heat, UV radiation, dehydration, pathogenic bacteria, fungi, parasites, and viruses. Pathogens invading the upper layers of the epidermis can cause keratinocytes to produce proinflammatory mediators, particularly chemokines which attract monocytes, natural killer cells, T-lymphocytes, and dendritic cells to the site of pathogen invasion. Basic for physiotherapy 1 (Lecture2) Basic for physiotherapy 1 (Tutorial 5)  Mescher AL (2018): Junqueira’s basic Histology Text and Atlas 14th edition Basic for physiotherapy 1 (Tutorial)