The study of tissues and how they are arranged into organs
What does Histology allow us to do?
Allows us to see how cells are arranged in a particular tissue type and how tissues help form an organ
4 primary tissue classes/categories
Epithelial, Connective, Nervous, Muscular
Tissue composed to layers of closely spaced cells that cover organs surfaces, form glands, and serve for protection, secretion and absorption
Tissue with more matrix than cell volume, often specialized to support, bind together and protect organs.
Tissue containing excitable cells specialized for rapid transmission of coded information to other cells.
Tissue composed of elongated, excitable cells specialized for contraction
Epithelial tissue is found in?
Inner Lining of digestive tract, Liver and other glands
Connective tissue is found in?
Tendons and ligaments, cartilage and bone, blood
Nervous tissue is found in?
Brain, spinal cord and nerves
Muscular tissue is found in?
Skeletalk muscles, heart (cardiac muscle) and walls of viscera (smooth muscle)
Tissues are made up of?
Cells and extracellular matrix
Extracellular material (NO CELLS) that the cells are supported by or bound to, composed of protein fibers, water, minerals, nutrients & waste products
A group of similar cells derived from a common embryonic origin that are arranged in a way that allows them to carry out particular structural or physiological functions
Bone (type of connective tissue) that supports and protects the body and allows muscles to produce movement
Epithelial tissues lining the digestive system allowing the body to absorb nutrients from the foods we eat
What epithelial tissues are bound to
Classifications of Epithelial Tissues
Squamous, Cuboidal, Columnar
Thin and flat, good for exchange of gasses, nutrients, wast products, found in lung and blood vessels
Typically square or round, found in the lining of the ducts of many glands
Tall and narrow, found lining the intestines, often have small projections on exposed surface of microvilli that increase surface areas of absorption
Simple Epithelial Tissues
Have a single layer of cells
Pseudostratified Columnar Epithelial
All cells are bound to the basement membrane but not all cells reach the exposed surface. Cells appear stratifies since nuclei are randomly distributed
Tissues contain a few to many layers of cells on top of each other, only the bottom layers are bound to the basement membrane, upper layers have cells bound to other cells (honey comb)
Specialized type of epithelia found in organs that stretch (bladder, ureter, umbilical cord)
Keratinized Stratified Squamous Epithelia
Many layers of cells, lower cells are alive and dividing, upper cells are dead and filled with keratin, cannot see nuclei
Non-keratinized stratified squamous epithelia
Many layers of cells, all alive, can see nuclei
Tissue that provides protection and support for the body and its organs, often composed of dense fibers large amount of extracellular material with relatively few cells
Major Functions of Connective Tissue
Connection, Support, Protection, Movement, Storage and heat protection, Transport
Types of Connective Tissue
Fibrous connective tissue, Cartilage, Bone & Blood
Fibrous Connective Tissue
A diverse type of connective tissue composed of cells, fibers, and ground substance (appears as empty space)
Types of Cells in Fibrous Connective Tissue
Fibroblasts, Macrophages, Leukocytes, Plasma Cells, Mast Cells, Adipocytes
Large cells that produce the fibers and ground substance
Phagocytotic cells that migrate trough the tissue, look for, engulf and destroy bacteria and viruses
Important part of immune system that monitors the body for pathogen invasion and coordinates immune response
Cells that produce antibodies when a bacteria or virus is detached
Proteins that recognize specific proteins on surface of invader and "flag" them so macrophages can destroy them
Contains granules of heparin (prevents blood clotting) and histamine (leaky blood vessels); make eicosanoids
Story triglycerides (fats) in large vacuoles
Types of Fibrous Connective Tissue Fibers
Collagenous fibers, Reticular fibers & Elastic fibers
Made of a protein called collagen, very strong, flexible but resists stretching, primary component of tendons, ligaments & deep skin layers
Collagen fibers coated with glycoproteins, form loose structural framework of organs like spleen and lymph nodes
Thin fibers made of protein elastin, allowing fibers to stretch and then return to its normal shaper, every important for elasticity of skin and lung tissue
Fils the space not occupied by fibers and cells, composed of large carbohydrates, proteoglycans and glycoproteins, cushion and protect the cells of the connective tissue, attract Na+ and water because many molecules are negatively charged
Types of Fibrous Connective Tissue
Loose fibrous connective tissue, Dense fibrous connective tissue
Loose fibrous connective tissue
Much more ground substance, 3 types - Areolar, Reticular and Adipose
Areolar loose fibrous connective tissue
Most wide spread loose connective tissue. Loosely organized fibers, abundant blood vessels and a lot of seemingly empty space, randomly oriented fibers (COLLAGEN & ELASTIN). Found under all epithelia, in serous membranes between muscles, passageways for n
Reticular loose fibrous connective tissue
Soft meshwork of reticular fibers and fibroblasts. Forms supportive stroma (framework) for lymphatic organs like the spleen lymph notes and bone marrow. Many randomly oriented RETICULAR fibers
Adipose loose fibrous connective tissue
Empty- looking cells with ting margins; nucleus pressed against cell membrane. Energy storage, insulation, cushioning (fat)Only a few fibers but many ADIPOCYTES filled with lipid
Dense fibrous connective tissue
Many more collagen fibers than found substance and cells, 2 types - Dense regular, Dense irregular
Dense regular fibrous connective tissue
Few cells, vey little ground substance, running parallel to each other. Collagen fibers are densely pack and parallel to each other. Very strong, good for tendons and ligaments
Dense irregular fibrous connective tissue
Very little ground substance, very few visible cells, collagen fibers are densely packed but run in random directions. Allows tissues to absorb pressure and resist mechanical stress. Commonly found beneath skin and surrounding internal organs
Flexible, rubbery connective tissue that plays an important supportive role, found in ears, nose, between bones of some joints and trachea. No blood vessels, no nerves 3 types.
Cells of cartilage that secrete the matrix and live in the small cavities called lacunae, surrounded by the matrix
Dense irregular connective tissue that surrounds some types of cartilage
Types of Cartilage
Hyaline, Elastic and Fibrocartilage
Clear glassy microscopic appearance because of unusual fineness of the collagen fibers, usually covered by perichondrium. Found in articular (joint) cartilage, costal cartilage, trachea, larynx, fetal skeleton. Eases joint movement, holds airway open (tra
Cartilage containing elastic fibers, covered with perichondrium, provides flexible, elastic support. Found in external ear and epiglottis.
Cartilage containing large, coarse bundles of collagen fibers. Never has perichondrium. Resists compression and absorbs shock. Found in pubic symphysis, menisci (knee joint) and intervertebral discs
The connective tissue commonly known as bone
Fibrous tissues that covers bones and serves as an anchor point of attachment of tendons and ligaments. 2 types.
Types of Osseous Tissue (bone)
Spongy bone & Compact bone
Osseous tissue found in the heads of long bones; microscopically, the tissues looks like a sponge
Dense osseous tissue that surrounds spongy bone. Bone cells are called osteocytes, which live in lacunae that surrounds the central canal.
Fluid connective tissue that plays an important role in transportation of many nutrients, hormones, blood clotting proteins, gasses and also very important in immune protection via leukocytes.
Non-cellular liquid ground substance that is 50-60% of blood volume
Red Blood Cells. Round with a faint center. The only cells in the body without a nucleus, little bags of hemoglobin
White Blood Cells. Large and have an obvious nucleus. 5 different types of cells all with specific functions that contribute to immune protection
Platelets. Cell fragments that are important in blood clotting, bud off from huge megakaryoctes that live in bone marrow
Specialized, "excitable" tissue found in central nervous system and peripheral nervous system.
Nervous tissues responsible for carrying electrical signals that are generated when there is a charge in electrical charge across the cell membrane
Central Nervous System
Brain and spinal Cord
Peripheral Nervous system
All the other nerves in our body
Nerve cells. Cells that transport electrical signals.
Support cells in the nervous system that nourish and protect the neurons
Cell body of the neuron, often round or oval shaped. This contains the nucleus and other organelles.
Short processes that RECEIVE signals coming from other neurons in the neuron
Large nerve fiber that SENDS signals to other neurons or eventually to final organ or tissue in an neuron
Specialized tissue with cells which are designed to contract when stimulated, 3 types
Types of Muscle Tissue
Skeletal, Cardiac & Smooth
Made up of long cylindrical cells (Muscle Fibers), over lapping Actin (thin filaments) an Myosin (thick filament) protein fibers causing Striations (alternating light and dark bands) Voluntary muscle tissue
Made up of shorter and often branched cells (Myoctyes), striated, contains only one nucleus located in the center of the cell, intercalated disks, involuntary muscle movement
Long cells that are thicker in the middle and tapers at the ends, No striations, One nucleus, involuntary
With he exception of blood cells, all the cell in out bodies need to be in contact with other cells or tissues to function normally so they use _____. 4 types
Types of Cell Junctions
Tight junctions, Gap junctions, Desmosome Hemidesmosome
Prevents passage of substances in between cells ; Zip-lock bag, surrounds the cells
Allows fast communication between cells, form a "patch"; Button and snap
Resists stretching, proteins (connexins) from a pore called connexon that join up with other connexons of adjacent cells
Attach cells to basement membrane
Organs or cells that produce a substance that is to be used by other nearby tissue, a tissue in another part of the body or eliminated from the body (waste). 2 categories.
Categories of glands
Endocrine glands & Exocrine glands
Glands that produce substances that will be used by other cells or tissues WITHIN the body, typically produce hormones