Human Histology - Textbook

HUMAN HISTOLOGY Name of Professor | Week number INTRODUCTION NERVOUS TISSUE: - control and coordinates body activities. HISTOLOGY - The study of the microscopic structure 1. EPITHELIAL TISSUE...

HUMAN HISTOLOGY Name of Professor | Week number INTRODUCTION NERVOUS TISSUE: - control and coordinates body activities. HISTOLOGY - The study of the microscopic structure 1. EPITHELIAL TISSUE of tissues. TYPES: Simple, Stratified, - Provides insights into the function and Pseuodostratified and Transitional. pathology of cells and tissues by FUNCTIONS: Protection, Secretion, allowing us to observe their detailed Absorption, and Filtration. structures and how they interact within the body. - Through the examination of tissue samples under a microscope, we can identify normal tissue architecture, and detect abnormalities that may indicate diseases such as inflammation, cancer, or degenerative (nakakamatay) conditions. 2. CONNECTIVE TISSUE - This understanding is crucial for TYPES: Loose, Dense, Cartilage, Bone and diagnosing diseases, guiding treatments, Blood. and researching cellular and tissue FUNCTION: Provides support, stores functions. energy and transport materials. EX. Drinks vitamins, minerals and calcium EX. diabetic patient that has GANGRENE or a dead body tissue. 3. MUSCLE TISSUE TYPE: Skeletal, Cardiac and Smooth FUNCTION: Movement, Posture, and Heat BRANCH OF HISTOLOGY production. GENERAL HISTOLOGY: study of the structure and function of tissues. SPECIAL HISTOLOGY: focuses on the microscopic structure organs. EX. heart and digestive PATHOLOGICAL HISTOLOGY: Examines diseased tissue. BASIC TISSUE TYPES EPITHELIAL TISSUE: - covers the body surfaces and lines cavities. CONNECTIVE TISSUE: - supports, binds and protects organs. MUSCLE TISSUE: - responsible for movement. Ariska’s Nine Bacon | 1 HUMAN HISTOLOGY Name of Professor | Week number 4. NERVOUS TISSUE COMPONENTS: ➔ DENDRITES: Branch-like structures that Neurons and Neuroglia receive signals from other neurons. FUNCTIONS: Transmits Electrical Signals, ➔ AXON: A long, slender projection that Process Information. transmits impulses away from the cell body to other neurons or effector cells. > NEUROGLIA ( Glial Cells ) FUNCTION: Neuroglia are supportive cells in the nervous system. ( They do not transmit electrical impulses like neurons, but they play crucial roles in maintaining the environment around neurons, providing support, protection, and nutrients, and assisting in signal transmission. TYPES AND FUNCTIONS: ASTROCYTES > NEURONS - Provide structural support, regulate FUNCTIONS: Neurons are the primary blood flow, maintain the blood-brain functional units of the nervous system. barrier, and regulate the chemical They are responsible for transmitting environment around neurons. electrical impulses and processing information. OLIGODENDROCYTES (CNS) and Schwann Cells (PNS): It communicates - Produce the myelin sheath, which with other neurons, insulates axons and speeds up muscles, and electrical signal transmission. glands, enabling sensations, MICROGLIA: movement, - Acts as the immune cells of the thought. central nervous system, protecting neurons by engulfing pathogens and debris. THREE PART OF NEURONS STRUCTURE: It has three parts Cell Body (Soma): ➔ CELL BODY (soma): Contains the - Contains the nucleus and most of the cell’s nucleus and most of the cell’s organelles. organelles. Ariska’s Nine Bacon | 2 HUMAN HISTOLOGY Name of Professor | Week number Dendrites: - Branch-like structures that receive signals EPENDYMAL CELLS: from other neurons. - Line the ventricles of the brain and the central canal of the spinal cord, which are involved in producing and circulating Axon: cerebrospinal fluid. - A long, slender projection that transmits impulses away from the cell body to other neurons or effector cells. NEUROGLIA (GLIAL CELLS) FUNCTION: Neuroglia are supportive cells in the nervous system. ○ They do not transmit electrical impulses like neurons but play crucial roles in maintaining the environment around neurons, providing support, protection, and nutrients, and assisting in signal transmission. TYPES AND FUNCTION: ASTROCYTES: - Provide structural support, regulate blood HISTOLOGICAL TECHNIQUE flow, maintain the blood-brain barrier, and regulate the chemical environment around FIXATION: Preserves tissue structure. neurons. STAINING: Enhances contrast (EX. Hematoxylin OLIGODENDROCYTES (CNS) and and Eosin). SCHWANN CELLS (PNS): - Produce the myelin sheath, which insulates MICROSCOPY: Light microscopy, electron axons and speeds up electrical signal microscopy. transmission. MICROSCOPY IN HISTOLOGY MICROGLIA: - Act as the immune cells of the central LIGHT MICROSCOPY: nervous system, protecting neurons by engulfing pathogens and debris. DEFINITION: Ariska’s Nine Bacon | 3 HUMAN HISTOLOGY Name of Professor | Week number Light microscopy uses visible light that passes RESOLUTION: through or reflects off a specimen to magnify and - Can achieve resolutions as fine as 0.1 view it. nanometers, allowing for visualization of much smaller structures, such as organelles RESOLUTION: within cells and even individual molecules. Typically, light microscopes can magnify objects up to about 1000-1500 times their TYPES: actual size, with a resolution of about 200 - Includes Transmission Electron Microscopy nanometers (nm). (TEM), which provides detailed images of internal structures, and Scanning Electron Microscopy (SEM), which gives three-dimensional images of surfaces. APPLICATIONS: - Used in advanced research, material science, and pathology to study cell ultrastructure, viruses, and nanomaterials in great detail. APPLICATION OF HISTOLOGY TYPES: MEDICAL DIAGNOSIS: Identifying - Includes brightfield, darkfield, diseases at the cellular level. phase-contrast, and fluorescence microscopy, each providing different RESEARCH: Understanding tissue contrast and visualization techniques. function and development. FORENSIC SCIENCE: Analyzing tissue APPLICATIONS: Commonly used in histology, samples in criminal investigations. biology, and medical labs to observe cells, tissues, and microorganisms. It’s useful for routine SUMMARY examinations, such as identifying cell structures and diagnosing diseases. Histology is the branch of biology that focuses on the microscopic study of ELECTRON MICROSCOPY: tissues, which are groups of cells that work together to perform specific functions. DEFINITION: There are four primary types of tissues in the - Electron microscopy uses a beam of human body: electrons instead of light to achieve much higher magnification and resolution. 1. Epithelial tissue Ariska’s Nine Bacon | 4 HUMAN HISTOLOGY Name of Professor | Week number (which covers surfaces and lines cavities) 2. Connective tissue (which provides and binds other tissues) 3. Muscle tissue (which enables movement) 4. Nervous tissue (which controls and coordinates bodily functions). Understanding histology allows scientists and medical professionals to diagnose diseases accurately, understand complex biological processes, and contribute to advances in medical science Ariska’s Nine Bacon | 5 HUMAN HISTOLOGY Name of Professor | Week number EPITHELIAL TISSUE Ectoderm: TISSUES - Outermost germ layer. Definition: Derived Tissues: - A tissue is a group of similar cells that work - Epidermis: Skin and associated structures together to perform a specific function. (hair, nails). Importance in Histology: - Nervous System: Brain, spinal cord, - Tissues are fundamental building blocks of peripheral nerves. organs and are essential for understanding the - Specialized Sensory Organs: Eyes, ears. structure and function of the body. Examples: Epidermal Tissue: Stratified squamous epithelium. THE FOUR BASIC Nervous Tissue: Neurons and glial cells. TISSUE TYPES Mesoderm: Epithelial Tissue: - Middle germ layer. - Covers body surfaces, lines cavities, and forms Derived Tissues: glands. - Musculoskeletal System: Muscles, bones, Connective Tissue: cartilage. - Provides support and structure, connects tissues - Circulatory System: Blood vessels, heart. and organs. - Connective Tissues: Tendons, ligaments, Muscle Tissue: adipose tissue. - Facilitates movement through contraction. Examples: Nervous Tissue: Skeletal Muscle Tissue: Striated muscle fibers. - Transmits signals and processes information. Bone Tissue: Osteocytes within a calcified matrix. Blood: Red blood cells, white blood cells. Endoderm: - Innermost germ layer. Derived Tissues: - Gastrointestinal Tract: Lining of the stomach, intestines. THREE GERM LAYERS - Respiratory System: Lining of the lungs, trachea. - Glandular Epithelium: Liver, pancreas. Examples: Simple Columnar Epithelium: Lining of the small intestine. Glandular Tissue: Hepatocytes in the liver. Ariska’s Nine Bacon | 6 HUMAN HISTOLOGY Name of Professor | Week number INTRODUCTION TO Secretion: EPITHELIAL TISSUE Secretes substances such as enzymes, hormones, Epithelial tissue is one of the four basic tissue and mucus. types, covering body surfaces and lining Example: Glandular epithelium in the pancreas. cavities. Filtration: General Characteristics of Epithelial Tissue Filters blood in organs like the kidneys. Cellularity: Example: Glomeruli in kidneys. Composed of closely packed cells with minimal extracellular matrix. Sensation: Polarity: Contains sensory receptors for various Distinct apical and basal surfaces. stimuli. Basement Membrane: Example: Olfactory epithelium in the nasal cavity. A supportive structure anchoring epithelial cells to underlying connective tissue. CLASSIFICATION OF Avascularity: EPITHELIAL TISSUE Lacks blood vessels, with nutrients By Cell Shape: supplied through diffusion. Squamous: Flat, Regeneration: scale-like cells. High capacity for renewal and repair. Cuboidal: Cube-shaped cells. Columnar: Tall, column-like cells. By Cell Layers: Simple Epithelium: Single layer of cells. FUNCTIONS OF Stratified Epithelium: EPITHELIAL TISSUE Multiple layers of cells. Protection: Pseudostratified Forms a barrier to protect underlying tissues Epithelium: Appears from mechanical damage, pathogens, and layered but is actually a dehydration. single layer with varying Example: Epidermis of the skin. cell heights. Transitional Epithelium: Absorption: Specialized for stretching (e.g., bladder). Absorbs nutrients and substances. Example: Intestinal lining. Ariska’s Nine Bacon | 7 HUMAN HISTOLOGY Name of Professor | Week number SIMPLE EPITHELIA Simple Squamous Epithelium: Single layer of flattened cells with disc-shaped central nuclei and sparse cytoplasm The simplest of the epithelia Location: Alveoli of lungs, lining of blood vessels (endothelium), and serous membranes STRATIFIED EPITHELIA (mesothelium). Function: Stratified Squamous Epithelium: Diffusion, filtration, and secretion. Keratinized: Found in the epidermis of the skin. Non-Keratinized: Found in the lining of the mouth, esophagus, and vagina. Function: Protection against abrasion, pathogens, and chemical attack. Simple Cuboidal Epithelium: Single layer of cubelike cells with large, spherical central nuclei Location: Kidney tubules, ducts of glands. Function: Stratified Cuboidal Epithelium: Secretion and absorption. Location: Ducts of sweat glands, mammary glands. Function: Protection and secretion. Simple Columnar Epithelium: Location: Stratified Columnar Epithelium: Lining of the gastrointestinal tract, gallbladder. Several cell layers Function: Basal cells usually cuboidal Absorption, secretion of mucus, and Superficial cells elongated and columnar enzymes. Ariska’s Nine Bacon | 8 HUMAN HISTOLOGY Name of Professor | Week number Location: Rare, found in the male urethra and large ducts of some glands. Function: Protection and secretion. Functional Significance SPECIALIZED EPITHELIA Protective Role: Pseudostratified Columnar Epithelium: Stratified epithelia provide a durable Location: Respiratory tract (trachea, bronchi). layer of defense in areas subject to wear and Function: Secretion of mucus, propulsion by ciliary tear. action. Absorptive and Secretory Functions: Simple epithelia, with fewer layers, are adapted for efficient absorption and secretion. Adaptation to Function: The structure of epithelial tissue is closely related to its function in different organs. Histological Features Basement Membrane: A thin, fibrous layer that anchors epithelial TRANSITIONAL EPITHELIUM tissue to underlying connective tissue. Location: Urinary bladder, ureters. Intercellular Junctions: Function: Permits expansion and recoil after Tight Junctions: Prevent leakage between stretching. cells Desmosomes: Provide mechanical strength. Gap Junctions: Allow communication between cells. Polarity: Apical surface faces the lumen or external environment; basal surface faces the underlying connective tissue. Ariska’s Nine Bacon | 9 HUMAN HISTOLOGY Name of Professor | Week number Infections: Clinical Relevance Respiratory and urinary infections often involve epithelial tissues. Carcinomas: Cancers arising from epithelial cells. Examples squamous cell carcinoma and adenocarcinoma. MICROSCOPIC STUDY OF TISSUE Cyst Formation: Biopsy: Occurs when epithelial cells form closed sacs removal of tissues for diagnostic purposes. filled with fluid or semi-solid material. Autopsy: examination of organs of a dead body to determine cause of death. Barrier Dysfunction: Conditions like psoriasis involve abnormal epithelial cell proliferation. Ariska’s Nine Bacon | 10 HUMAN HISTOLOGY Name of Professor | Week number INTRODUCTION TO Adipocytes: Store fats CONNECTIVE TISSUE Mast cells: Mediate allergic reactions Plasma cells: Produce antibodies - Connective tissue is one of the four main types of tissues in the body. EXTRACELLULAR MATRIX (ECM) FIBERS: - It supports, connects, or separates different types Collagen fibers: Provide strength of tissues and organs. Elastic fibers: Provide elasticity Reticular fibers: Form supportive networks MAIN FUNCTION ▪Structural support ▪Protection of organs ▪Transportation of fluids (blood, lymph) ▪Energy storage (adipose tissue) ▪Defense (immune responses) COMPOSITION OF CONNECTIVE TISSUE GROUND SUBSTANCE Proteoglycans, glycosaminoglycans (GAGs), and glycoproteins: Facilitate the diffusion of nutrients and waste CLASSIFICATION OF CONNECTIVE TISSUE CONNECTIVE TISSUE PROPER 1. Loose Connective Tissue AREOLAR - Function: Provides elasticity, strength, and support - Location: Beneath epithelial tissue, around blood vessels CELLS: - Histology: Contains collagen and elastic fibers, Fibroblasts: Produce fibers and ground substance fibroblasts, macrophages Macrophages: Phagocytic cells, part of immune defense ADIPOSE Ariska’s Nine Bacon | 11 HUMAN HISTOLOGY Name of Professor | Week number - Function: Stores energy, insulates, and cushions DENSE IRREGULAR CT organs - Location: Subcutaneous tissue, around organs - Histology: Large fat droplets, nucleus pushed to the side RETICULAR - Function: Provides strength in multiple directions - Location: Dermis of skin, capsules of organs - Histology: Irregularly arranged collagen fibers ELASTIC CT - Function: Supports the framework of lymphatic organs - Location: Lymph nodes, spleen, bone marrow - Histology: Reticular fibers and white blood cells - Function: Allows stretch and recoil 2. Dense Connective Tissue - Location: Walls of large arteries, bronchial tubes - Histology: Dense elastic fibers SPECIALIZED CONNECTIVE TISSUE 1. Cartilage: Hyaline, Elastic, Fibrocartilage DENSE REGULAR CT - Function: Provides tensile strength - Location: Tendons, ligaments HYALINE CARTILAGE - Histology: Parallel collagen fibers with fibroblasts Ariska’s Nine Bacon | 12 HUMAN HISTOLOGY Name of Professor | Week number - Histology: Thick collagen fibers 2. Bone: Compact Bone, Spongy Bone - Function: Provides support with flexibility - Location: Nose, trachea, larynx, ends of long bones COMPACT BONE - Histology: Chondrocytes in lacunae, glassy matrix ELASTIC CARTILAGE - Function: Supports and protects, stores calcium - Location: Outer layer of bones - Histology: Osteons, concentric lamellae, central canal - Function: Maintains shape while allowing SPONGY BONE flexibility - Function: Lightweight, supports bone marrow - Location: External ear, epiglottis - Location: Inside bones - Histology: More elastic fibers in matrix - Histology: Trabeculae with red or yellow marrow 3. Blood: Fluid Connective Tissue FIBROCARTILAGE - Function: Absorbs compressive shock - Location: Intervertebral discs, pubic - Function: Transports oxygen, nutrients, waste, and symphysis immune cells Ariska’s Nine Bacon | 13 HUMAN HISTOLOGY Name of Professor | Week number Components: ▪Stores energy (adipose tissue) - Red Blood Cells (RBCs): Oxygen transport ▪Stores minerals (bone tissue) - White Blood Cells (WBCs): Immunity - Platelets: Clotting Repair and Healing: - Plasma: Carries dissolved substances ▪Fibroblasts play a crucial role in wound healing ▪Collagen deposition aids in tissue repair 4. Lymph: Interstitial fluid involved in immune responses CLINICAL CORRELATIONS CONNECTIVE TISSUE DISEASE Marfan Syndrome: Genetic disorder affecting elastic fibers Definition: Osteogenesis Imperfecta: Defect in collagen production, Lymph is a clear, interstitial fluid that circulates in the leading to brittle. lymphatic system, playing a crucial role in immune responses. Composition: Contains lymphocytes (a type of white blood cell), proteins, and waste products. Function: Transports immune cells to sites of infection or injury. Helps in the removal of toxins, waste, and pathogens from Ehlers-Danlos Syndrome: Hyperelastic skin and tissues. hypermobile joints due to abnormal collagen. Maintains fluid balance between blood and tissues. Histology: Composed of lymphatic vessels, lymph nodes, and lymphatic organs (like the spleen and tonsils). Lymph nodes filter out pathogens, and lymphocytes attack foreign invaders. HISTOPHYSIOLOGY OF CONNECTIVE TISSUE Structural Function: Supports epithelial tissue and organs. Binds tissues together. Defense Mechanism: Contains immune cells (macrophages, lymphocytes). Fights infections and repairs damaged tissues. Storage Function: Ariska’s Nine Bacon | 14 HUMAN HISTOLOGY Name of Professor | Week number Ariska’s Nine Bacon | 15