General Histology 1/ Physiotherapy PDF

GENERAL HISTOLOGY 1/ PHYSIOTHERAPY PT0103 2024-2025 PROF. GEHAN KHALAF MSA  General Histology 1/ physiotherapy Lecture 1: Cytology I [ cell membrane and inclusio...

GENERAL HISTOLOGY 1/ PHYSIOTHERAPY PT0103 2024-2025 PROF. GEHAN KHALAF MSA  General Histology 1/ physiotherapy Lecture 1: Cytology I [ cell membrane and inclusion] By the end of this lecture, students will be able to : 1. Identify different components of the cell. 2. Describe the cell membrane structure 3. Outline the roles of phospholipid, cholesterol, protein and CHO. 4. Identify the difference between cell membrane and other membranes in the cell 5. Identify the bulk transport, different types of endocytosis and exocytosis. Dr. Gehan Khalaf Page 1  General Histology 1/ physiotherapy The cell (Eukaryotic): Structural & functional unit of living organism Cytoplasm Nucleus Eukaryotic cell has nuclear membrane &its DNA bound to protein Hyaloplasm (cytosol) Suspended bodies Clear colloid solution Contains 1-enzymes 2- protein 3- nutrients Organelles Inclusions (little organ) Living, organized & essential for the cell Nonliving, non-organized & nonessential Membranous Pigments Stored food Exogenous Glycogen 1. Cell membrane 1. Carbon /dust 2. Mitochondria 2. Tattoo Endogenous Fat 3. Endoplasmic reticulum 1. Hemoglobin 4. Golgi apparatus 2. Melanin 5. Lysosomes  Non membranous 1. Ribosomes 2. Microtubules 3. Filaments Dr. Gehan Khalaf Page 2  General histology I I.Inclusions: 1- Pigments Exogenous pigments (come from Endogenous pigments (synthesized inside the outside the body). body). a- tatoo a- Hemoglobin b- Dust and carbon particles b- Melanin 2- Stored food Glycogen (carbohydrates) Fat (lipid)  Mainly in liver & muscle cells  Mainly in fat cells (adipocytes)& liver cells  LM: Stained by PAS.--> purple  LM: stained by sudan black or sudan III II. Organelles Cell membrane(Plasma lemma) Definition: The thinnest layer surrounding the cell = 8- 10 nm L.M: Can’t be seen….. Why?..................................... E.M: 1- Trilaminar : Three layered structure outer electron dense, inner electron dense & intermediate electron lucent  All membranes of organelles have this appearance, SO it is called unit membrane 2- A fuzzy (filamentous) electron dense layer on the outer aspect = cell coat. Dr Gehan Khalaf Page 7  General histology I Molecular structure of cell membrane: Features Function 1- Lipid 50% Have hydrophilic head and hydrophobic Act as a barrier between tail extra and intra cellular a.Phospholipids  Form lipid bilayer aqueous media.  Between the phospholipids tails Has stabilizing effect and b- Cholesterol  in inner and outer half of lipid bilayer increase rigidity of cell membrane 2- Protein 50%  Two types: Act as: 1. Integral or intrinsic: Transport protein, [Carriers- Embedded in lipid bilayer either Pump – Channels] 2. Peripheral or extrinsic : loosely bound, Part of Cytoskeleton 3-  Present on the outer aspect of cell Function as specific receptors Carbohydrates membrane for:  Formed of glycoprotein& glycolipid a- Adhesion. Cell coat or glycocalyx  By EM appear as a fuzzy (filamentous) b- Recognition. layer on the outer aspect of cell c- Response to hormone. membrane Dr Gehan Khalaf Page 8  General histology I Function of cell membrane I- Selective barrier for transport between intercellular & extracellular 1- Passive transport ( diffusion): With concentration gradient & no need of energy 2- Active transport: Against concentration gradient – need ATP & pump 3- Bulk (vesicular) transport:  Exocytosis: Fusion of membranous vesicles with cell membrane & release its content to the extra cellular fluid.  Endocytosis: Cell engulf a part of extra cellular compartment & surround it by membrane to form vesicle. There are 3 types: Pinocytosis Phagocytosis Receptor mediated endocytosis Cell Fluid Solid selective uptake of Receptor& engulf its ligands (a molecule with high affinity to a receptor), To Pinocytotic vesicles phagocytic vesicles coated vesicles form Dr Gehan Khalaf Page 9  General histology I Lecture 2: Cytology II [Cytoplasmic organelles] By the end of this lecture, students will be able to : 1. Describe the light and electron microscopic features of organelles. 2. Correlate the function of the organelles with the function of the cell. 3. Interpret the structural changes in cell to understand the underlying cause of different diseases. Dr Gehan Khalaf Page 10  General histology I Mitochondria Definition: Membranous organelles. Largest organelles 1 x 10 µm in size E.M.: Outer membrane Smooth Inner membrane - Rough (folds-cristae) to increase surface area. - The space inbeween the 2 membranes is called inter- membranous space. Cristae Contains ATP synthase enzyme. Matrix space Electron dense granules ( ca), (Intercristae) Enzymes of Carbohydrate and lipid metabolism, DNA , RNA + Ribosomes  So it can self- divide and Form its own protein Function Energy production  The number of mitochondria & its cristae increase in cells with high energy metabolism eg. liver cells & muscle cells Medical application Deficiency of mitochondrial enzymes leads to impairment of tissues with high energy requirements as muscle & nervous tissues Ribosomes Dr Gehan Khalaf Page 11  General histology I Def. : Non membranous organelle consists of ribonucleo-protein particles (rRNA+protein) It is formed in nucleolus 2 Types 1- Free ribosomes: 2- Attached ribosomes: L.M: basophilic cytoplasm due to its high content of rRNA. E.M: electron dense granules, 2 subunits ( small – large ) Clusters connected by m.RNA Attached to rough endoplasmic (Polysomes) reticulum RER by its large subunits Function Protein synthesis ( ribosomes translate the code of amino acid sequence on mRNA.) Synthesis of protein which Synthesis of protein which need remains in cytoplasm for use to be segregated into RER such within the cell as : 1- secretory protein 2- lysosomal enzymes 3- Integral protein of plasma membrane Dr Gehan Khalaf Page 12  General histology I Endoplasmic reticulum (membranous organelle) 2 types Rough endoplasmic reticulum RER Smooth endoplasmic reticulum SER LM basophilic cytoplasm Acidophilic cytoplasm EM: 1. Network flat membranous sacs 1. Network of membranous tubules called a cisternae 2. Not covered by ribosome 2. Parallel & Interconnected 3. continuous with RER 3. Covered by ribosomes 4. Continuous with the outer nuclear membrane. Function: Synthesis of protein which need be 1. Phospholipid synthesis, for all segregated into RER such as secretory cell membranes. protein- enzymes of lysosomes- 2. Steroid hormone synthesis, as integral protein of cell membrane in cells of adrenal cortex.  They are very prominent in 3. Glycogen synthesis, as in liver protein secreting cells &muscle cells 4. Drug detoxification, in liver cells 5. Ca storage & pump, in muscles Golgi apparatus GA Membranous organelle EM: Golgi saccules are formed of: - Curved membranous cisternae - Inter connecting - Have 2 face; 1. Convex, cis, immature face receive the transfer vesicles from RER 2. Concave, trans, mature face from which lysosomes and secretory vesicles are released. Function 1- Concentration & Modification of protein 2- Sorting & package different proteins to transport to their sites. Secretory proteins , lysosomes and Integral membrane protein Dr Gehan Khalaf Page 13  General histology I  Lysosomes Def.: Membranous organelle / Abundant in phagocytic cells LM: Cannot be seen, EM: 2 types can be identified - 1 ary Lysosomes Homogenous electron dense vesicles./Newly formed not entered in digestive process ‫ ־‬2ary Lysosomes Heterogeneous electron dense vesicles. / Entered in digestive process Function: Intra-cytoplasmic digestion of any engulfed materials & old organelles Different pathways that deliver material to be digested in lysosomes 1. Extra cellular large solid particle  engulfed by phagocytosis  form hetero-phagosomes that bind with primary lysosomes  lysosomes [2ary] 2. Intracellular particles eg. Old organelle  surrounded by a membrane In a process called [Autophagy] -> form autophagosomes that bind with primary lysosomes  lysosomes [2ary]  The undigested particles [debris] remain within the vacuole and called residual body Medical application  Deficiency of lysosomal enzymes  accumulation of unwanted and undigested material within the cells which interfere with the normal functions Dr Gehan Khalaf Page 14  General histology I Lecture 3: Cytology III [Cytoskeleton and nucleus] By the end of this lecture, students will be able to : 1. Identify the components and function of cytoskeleton 2. Describe the structure and function of microtubules 3. Outline the structure and function of centriole, cilia and flagella 4. Identify the types of filaments and its significance 5. Identify structure and function of different components of the nucleus (chromatin, nuclear envelope and nucleolus) 6. Compare between the 2 types of chromatin. 7. Interpret the structural changes in cell to understand the underlying cause of different diseases. Dr Gehan Khalaf Page 15  General histology I  Microtubules Non membranous organelle - The wall of the tubules consist of protein subunits called tubulin. Sites: Medical application 1- Cytoplasm ( as a part of cytoskeleton).  Chemotherapeutic drugs  prevent 2- Centrioles formation of microtubules  stop cell 3- Cilia & flagella division 4- Mitotic spindles Movement of chromosomes along mitotic spindles in cell division  Centrioles - Paired structure, close to nucleus called (centrosome) - 2 cylinders, perpendicular - Its wall formed of: 9 triplets of microtubules = 27 microtubules - Function: Formation of mitotic spindle, cilia & flagella  Cilia; Motile processes with microtubules core 1. Shaft - 2 singlets microtubules in the center + 9 doublets microtubules peripheral, having dynein arm with ATPase activity for movement - Covered by a cell membrane 2. Basal body: similar to centriole (9 triplets of MTs) 3. Rootlets microtubules extend from basal bodies to fix in the cytoplasm Function: Help movement of particles in one direction over surface of cell; in Respiratory epithelium Medical application Congenital deficiency of dynein arm in cilia  immotile cilia  repeated respiratory tract infection  Flagella is a long single cilium found in sperm and infertility Dr Gehan Khalaf Page 16  General histology I Filaments Non membranous organelle 3 types 1- Thin , microfilaments = 6 nm filaments ,formed of Actin protein. 2-Thick filament = 16 nm filaments ,formed of Myosin protein. 3- Intermediate filaments 10 -12 nm Function of cytoskeleton ( Microtubules, microfilaments& intermediate filaments) : 1- Shaping & support of cell 2- Movement of organelles & vesicles inside the cell 3- Movement of entire cell Dr Gehan Khalaf Page 17  General histology I Nucleus  Nuclear envelope Thin line surrounds the nucleus LM EM Function Dark basophilic 1. Double membrane+ Nuclear pores Provide selective line b. Outer membranous layerCovered pathways between with ribosomes / Continuous with nucleus & cytoplasm RER through nuclear pores. c. Inner membranous layer-> attached to Fibrous lamina & Peripheral heterochromatin  Chromatin; Coiled strands of DNA bound to basic protein ( histone) Types of Heterochromatin Euchromatin chromatin Coiled & condensed / Inactive / Extended & uncoiled / Active (more DNA Dark stained surface available for transcription) / Light- stained LM Basophilic granules Can’t be seen EM Electron dense granules Thin pale threads a- peripheral chromatin b- Nucleolus associated c- Chromatin islands Nucleolus ;Site of ribosome subunits formation  Active cells have euchromatin > heterochromatin The nucleus appears light stained, vesicular or open face nucleus.  Inactive cells have heterochromatin > euchromatin. The nucleus appears dark stained or condensed nucleus. Dr Gehan Khalaf Page 18  General histology I Lecture 4: Epithelium By the end of this lecture, students will be able to : 1. Describe the general characteristics of the epithelial tissue. 2. List the types of epithelial tissue. 3. Describe the structure and correlated functions of each type of epithelial membranes. 4. Asses the significance of different types of the cell junctions. Dr Gehan Khalaf Page 19  General histology I The human body is composed of four basic tissues: Epithelial, Connective, Muscular and Nervous tissues.  Main characters of the epithelial tissue: – Covers surfaces (covering epithelium) or lines cavities. – Mainly of cells with little intercellular substances. – The cells lie on a basement membrane. – The cells are hold together by cell junction. – No blood vessels or lymphatics enter in between the cells (avascular), [Nourishment of epithelial tissue occurs by diffusion of nutrients and oxygen from the blood vessels present in the underlying connective tissue]. – There are nerve fibers in between the cells. – Epithelial cells are continuously renewed and replaced. Classification of Epithelial Tissue I- Surface epithelium [epithelial membranes] – Covers surfaces or lines cavities II- Glandular epithelium – It is a special type of epithelium characterized by its secretory function. – Glands originate from epithelial cells that leave the surface and penetrate the underlying connective tissue. Types of glandular epithelium – Exocrine glands: when the cells are connected to the surface by duct. – Endocrine gland:. When the cells lose their connection to the surface. Their secretion called hormones and enter the blood III- Neuroepithelium  It is a special type of epithelium which is modified to receive stimuli of some special sensations and convert them into electrical impulses.  Sites: – Taste buds for taste sensation. Dr Gehan Khalaf Page 20  General histology I I - Surface epithelium – Covers surfaces or lines cavities – Classified according to the number of cell layers into: A. Simple epithelium: formed of a single layer of epithelial cells. B. Stratified epithelium: formed of several layers. A- Simple epithelium 1-Simple squamous epithelium.  One layer of flat cells and a flat nucleus.  Sites: – Lining the blood vessels (endothelium). – Lining the serous membranes: pleura, pericardium and peritoneum (mesothelium). – Lining the lung alveoli and Bowman’s capsule of the kidney  Functions: This type of epithelium is adapted to form a thin membrane for transport & diffusion, and smooth surface to facilitates movement of the viscera. 2- Simple cuboidal epithelium  a single layer of cubical cells and rounded central nucleus.  Site: – Lining duct of the glands.  Function: covering surfaces. 3- Simple columnar epithelium:  a single layer of columnar cells and basal oval nucleus.  Types and sites: – Unmodified columnar cells: lining ducts of the glands. – Modified columnar cells: (secretory, absorptive or ciliated): 1. Secretory: Lining epithelium of the stomach. 2. Absorptive: Have microvilli to increase the surface area for absorption ex. the lining epithelium of the small intestine. 3. Ciliated: Have cilia ex. uterus. 4- Pseudostratified columnar epithelium:  The cells are overcrowded, but they all rest on the basement membrane. Some cells appear short and not reaching the surface. The nuclei appear at different levels giving a false impression of being a stratified type.  Types and sites: Dr Gehan Khalaf Page 21  General histology I a. Non-ciliated: Large ducts of salivary glands. b. Ciliated: The surface of the cells is provided by cilia and usually associated with goblet cells e.g. trachea, bronchi [RESPIRATORY EPIHELIUM]. B-Stratified epithelium  Formed of more than one layer of cells.  Types of stratified epithelium: 1- Stratified squamous epithelium: a. Stratified squamous non-keratinized epithelium: - Basal: one layer of columnar cells, - Intermediate : several layer of polygonal cells - Superficial : thin squamous cells at the surface.  Sites: It is found in wet surfaces of all openings leading to the skin such as: oral cavity, tongue, oesophagus, cornea, anal canal and vagina.  Function: protection b. Stratified squamous keratinized epithelium  It is similar to the stratified squamous non-keratinized epithelium but the flat cells of the top layer are covered by non-living layer of keratin. This type is tough, resists friction and is impermeable to water.  Sites: Epidermis of the skin.  Function: protection 2- Stratified cuboidal epithelium:  The cells in uppermost layer are cubical in shape. 3-Stratified columnar epithelium:  The cells in the uppermost layer are columnar cells. 4-Transitional epithelium [Urothelium]:  It is highly specialized to withstand a great degree of distension.  Sites: In the urinary system: Pelvis of the kidney, ureters, urinary bladder.  In the empty state, it is formed of 6-8 layers of cells:  In the stretched state:2-3 layers. Dr Gehan Khalaf Page 22  General histology I Cell junctions Types of cell junctions 1.Occludens (tight) Junction:  Fusion of outer layer of 2 adjacent cell membranes to Close the inter- celullar space (ICS) to prevent passage of any substances between the cells, so it act as a barrier  found in Intestinal epithelium & Endothelium of blood capillaries 2. Adhering Junction [as desmosomes & zonula adherens] Lateral borders of adjacent cells are connected by filaments to form strong adhesion. Found in Intestinal epithelium & Epidermis of the skin 3. Gap junction (Communicating junction ) – Cells have narrow ICS & joined by channels  communication & passage of substances – It is found also in non epithelial tissue: Cardiac muscle fibers, nerve cells, bone cells and smooth muscle fibers. Dr Gehan Khalaf Page 23  General histology I Lectures 5: Connective tissue By the end of this lecture, students will be able to : 1- Describe the general structure of the connective tissue. 2- Describe the structure and staining properties of the collagen, elastic and reticular fibers with correlation to function. 3- Describe the structure and correlated functions of the different types of the connective tissue cells. 4- Describe the sites, structure and correlated functions of the different types of the connective tissue proper. Dr Gehan Khalaf Page 24  General histology I General characters of the connective tissue [CT]: -It connects, binds and supports other tissues and organs. -It consists of few cells, and wide intercellular space filled ith extracelluar matrix[ECM]. -It is penetrated by blood vessels, lymphatics and nerves. Types of connective tissue:  Connective tissue proper  Special types : Cartilage, Bone & Blood connective tissue proper [Loose (areolar) Connective Tissue CT] Cells Extra cellular matrix Fibers Ground substance 1. Collagen fibers are tough and provide tensile strength o 2. Elastic fibers allow for stretch Tissue fluid o 3. Reticular fibers make networks. Macromolecules Derived from proteoglycans and the blood glycoprotein capillarie Dr Gehan Khalaf Page 25  General histology I Connective tissue fibers 1-Collagen fibers type I/ white fibers White in color in fresh state Tough and flexible, resist tension Thick, long & Non-branching fibers Form wavy branched bundles Collagen fibers are synthesized by fibroblasts Medical application Scurvy [ vitamin C DEFICIENCY] Defect in synthesis of collagen patient will suffer from bleeding gum, loose teeth, poor wound healing, poor bone development 2-Reticular fibers o Formed of type III collagen. o Thin short branching fibers form networks. o They are synthesized by fibroblasts 3-Elastic fibers o Formed of elastin protein o Elastic fibers are yellow in color in fresh state. o They are stretchable but regain their original length. o Are thin, long and branching fibers ,not form bundle o Synthesized by fibroblasts Connective tissue cells Cells of the connective tissue are classified according to their shape into: Branched cells Oval or rounded cells UMCs Mast cells Fibroblasts Plasma cells Pericytes Fat cells Macrophages Extravasated leucocytes Pigment cells Dr Gehan Khalaf Page 26  General histology I 1. Undifferentiated Mesenchymal Cells (UMCs) Origin: young embryonic mesenchymal tissue. Functions:  UMCs can differentiate to other C.T cell. And other structures as blood cells, smooth muscle fibers and endothelial cells. 2. Pericytes Origin: UMC Sites: surround the endothelium of blood capillaries and small venules. They usually lie between the endothelial cells and their basement membrane. Functions:  Pericytes are postnatal UMCs, can differentiate into fibroblasts, smooth muscle fibers, endothelial cells and osteogenic cells.  Contractile  control the diameter of blood capillaries. 3. Fibroblasts Origin: UMCs, pericytes. Site: most common cell in the C.T. Functions:  Synthesis of ECM [connective tissue fibers + Macromolecules). 4. Pigment Cells, melanophore Origin: UMCs, pericytes Sites: iris of the eye, dermis of the skin. Functions:  Store melanin pigment to protect the tissues from the harmful effects of ultraviolet rays. 5. Macrophages [histiocytes] Origin: blood monocytes. Functions:  Phagocytosis: they phagocytose foreign particles, bacteria and microorganisms. Dr Gehan Khalaf Page 27  General histology I 6. Mast Cells Origin: progenitor cells in the bone marrow. Functions:  Synthesis, storage and secretion of: heparin, histamine.  In allergy: mast cells release histamine and heparin which promotes the allergic reactions known as hypersensitivity reaction 7. Plasma Cells Origin: B-lymphocytes Functions:  Synthesis and secretion of antibodies (immunoglobulins). 8. Fat Cells (adipose cells) Origin: UMCs. Types: A) Unilocular B) Multilocular A- Unilocular adipose cells Sites: [in white adipose CT] Subcutaneous tissue, around blood vessels, around kidneys Functions:  Synthesis and storage of fat.  Heat insulation.  Supporting function e.g. fat around the kidney. B-Multilocular adipose cells Sites: [Brown adipose CT] Fetuses and new born. Multilocular adipose cells produce heat and thus protect the newborn against cold. It is greatly reduced in adulthood [present in interscapular and neck region only]. It is called brown fat due to high content of mitochondria and rich blood vessels  Functions:  Heat generation. Extravasated Leucocytes Leucocytes (neutrophils, eosinophils, lymphocytes, basophils and monocytes) leave the blood stream to enter the connective tissue to perform immune functions.  Free cells in CT : leucocytes plasma cells mast cells free macrophage Dr Gehan Khalaf Page 28  General histology I Special Types of connective tissue proper 1- Dense Collagenous Connective Tissue: Formed mainly of collagen fibers + fibroblast A) Dense irregular collagenous connective tissue Fibroblasts and irregular bundles of collagen fibers resists stretch from all directions. Sites -Capsules of organs. -Periosteum and perichondrium B) Dense regular collagenous connective tissue Fibroblasts and regular collagen bundles that resist tensile forces. Sites: – Tendons and ligaments 2- Elastic Connective Tissue: Fibroblasts and elastic fibers. Sites: – Ligamentum nuchae. 3- Reticular Connective Tissue Fibroblast and reticular fibers that form networks. Sites: stroma of any organs. Dr Gehan Khalaf Page 29