BIOL 260 Chapter 5 The Human Tissues PDF

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This is the key to exam 1, I have provided the correct answers and reasoning as to why they are correct. The exam was produced by Jennifer Mansfield-Jones and has been since handed back to students to review on their own....

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Chapter 5: The Human Tissues 5.1 The Study of Tissues 1. Name the four primary classes in which all adult tissues are classified 2. Name the three embryonic germ layers and some adult tissues are classified 3. Visualize the three-dimensional shape of structure from a two-dimensional tissue section

5.1a The Primary Tissue Classes ● Tissue: A group of similar cells and cell products that arise from the same region of the embryo and work together to perform a specific structural or physiological role in an organ ● The four primary tissues: ○ Epithelial ○ Connective ○ Nervous ○ Muscular ● The primary tissues differ in: ○ Types and functions of their cells ○ The characteristics of the matrix (extracellular material) ○ The relative amount of space occupied by the cells and matrix ● In muscles and epithelium the cells are so close together that the matrix is scarcely viable ○ This is opposite in connective tissue as the matrix occupies more space than the cells do The Four Primary Tissue Classes Type

Definition

Representative Locations

Epithelial

Tissues composed of layers of closely spaced cells that cover organ surfaces, form glands, and serve for protection, secretion, and absorption

-Epidermis -Inner lining of digestive tract -Liver and other glands

Connective

Tissue with usually more matrix than cell volume, often specialized to support and protect organs and to bind other tissues and organs to each other

-Tendons and Ligaments -Cartilage and Bone -Blood

Nervous

Tissue containing excitable cells specialized for rapid transmission of coded information to other cells

-Brain -Spinal Chords -Nerves

Muscular

Tissue composed of elongated, excitable muscle cells specialized for contraction

-Skeletal Muscles -Heart (Cardiac Muscles)

-Walls of Viscera/Smooth Muscles ● The matrix is composed of fibrous proteins and a clear gel known as ground substance, tissue fluid, extracellular fluid (ECF) or Intestinal fluid ○ In cartilage and bones this fluid is more of a rubbery or stony consistency ● In short: Tissue is composed of cells and matrix, matrix is composed of fibers and ground substances

5.1b Embryonic Tissues ● Human development: single cell → fertilization → creation/division of identical smaller cells ● Primary Germ Layers - The first three strata that appear when the first tissue cells start to organize themselves into a layer ● The three primary germ layers are called Ectoderm, Mesoderm, and Endoderm ○ Ectoderm: Outer layer that gives rise to the epidermis and nervous system ○ Endoderm: The innermost layer that gives rise to the mucous membranes of digestive and respiratory tracts and to the digestive glands ○ Mesoderm: The in-between layer of loosely organized cells that eventually turns into mesenchyme ■ Mesenchyme: A gelatinous tissue, composed of fine, wispy collagen fibers and branching mesenchymal cells embedded in a gelatinous ground substance

5.1c Interpreting Tissue Sections ● Sectioning a tissue reduces a 3D structure into a series of 2D slices ● An object looks very different when cut into sections/slices, so it is important to remember that when looking at slices under a microscope ● Tissues specimen are preserved in a fixative or a chemical such as formalin that preserves decay ● Sections can be mounted onto slides and stained to enhance detail ● Longitudinal Section: A tissue cut on it’s long axis ● Cross Section: A tissue cut perpendicular to its long axis ● Oblique Section: A section cut on a slant between a longitudinal and cross section

● Not all histological preparations are sections however ○ Liquid tissues such as blood and soft tissues (spinal cord) may be prepared as smears ● Smears: Tissue that is rubbed or spread across the slide rather than sliced ● Some membranes and cobwebby tissues like the areolar tissue are sometimes mounted as spreads ○ Spreads: The tissues is laid out on the slide

5.2 Epithelial Tissues 1. Describe the properties that distinguish epithelium from other tissue classes 2. List and classify eight types of epithelium, distinguish them from each other, and state where each type can be found in the body 3. Explain how the structural differences between epithelia relate to their functional differences 4. Visually recognize each epithelial type from specimen on photographs

● Epithelial Tissue consists of a sheet of closely adhering cells, is one or more cells thick, with the upper surface usually exposed to the environment or to an internal space in the body ○ Covers the body surface, lines body cavities, forms the external and internal linings of many organs, and constitutes most gland tissue

● The functions of epithelial tissue include: ○ Protection: Protects deeper tissues from invasion and injury ■ Ex. The epidermis of the skin and the inner lining of the stomach ○ Secretion: Produce mucus, sweat, enzymes, hormones, and most of the body’s other secretions ■ Glands are composed largely of epithelial tissue ○ Excretion: Voids waste from the tissues such as CO2 across the pulmonary epithelium and bile from the epithelium of the liver ○ Absorption: Absorb chemicals from the adjacent medium ■ Ex. Nutrients that are absorbed through the epithelium of the liver ○ Filtration: All substances leaving the blood are selectively filtered through the epithelium that lines the blood vessels ■ Ex. Urinary waste is filtered through epithelium of the kidneys ○ Sensation: Provided with nerve endings that sense stimulation ranging from a touch on the skin to irritation of the stomach ● Between an epithelium and the underlying connective tissue is a layer called the basement membrane ○ It contains collagen, glycoproteins, and other protein-carbohydrate complexes ● Basal Surface: The surface of an epithelial cell that faces the basement membrane ● Apical Surface: The surface that faces away from it toward the body surface or the internal cavity of an organ ● Lateral Surface: The “sidewall” of the cell located between the basal and apical surface

5.2a Simple Epithelia ● Only has one layer of cells ● Three types of simple epithelia: ○ Simple Squamous - Thin scaly cells ○ Simple Cuboidal - Squarish or round cells ○ Simple Columnar - Tall narrow cells ● In a Pseudostratified Columnar cell, not all cells can reach the surface and the shorter cells are covered by the taller ones

5.2b Stratified Epithelia ● Range from 2 to 20 more more layers of cells ○ Some cells resting directly on others and only the deepest layer attached to the basement membrane ● Three types of stratified epithelia ○ Stratified Squamous ○ Stratified Cuboidal ○ Stratified Columnar Epithelia

● A Urothelium is named for the fact that it’s unique to the urinary tract ● When a cell dies and flakes off it is called exfoliation ○ Think of when we exfoliate our skin to get rid of the rough/dead skin on the targeted area of exfoliation

5.3 Connective Tissue 1. Describe the properties that most connective tissues have in common 2. Discuss the types of cells found in connective tissue 3. Explain what the matrix of a connective tissue is and describe its components 4. Name and classify 10 types of connective tissue, describe their cellular components and matrix, and explain what distinguishes them from each other 5. Visually recognize each connective tissue type from specimen or photographs

5.3a Overview ● Connective Tissues are the most abundant, widely distributed, and histologically variable of the primary tissues ● Functions of connective tissues: ○ Binding of Organs - Tendons bind muscle to bone, ligaments bind bone to another, fat hold the kidneys and eyes in place, etc. ○ Support - Bones support the body; cartilage supports the ears, nose, larynx, and trachea; fibrous tissue form the framework of organs ○ Physical Protection - The cranium, ribs, and sternum protect delicate organs such as the brain, lungs, and heart ○ Immune Protection - Connective tissue cells attack foreign invaders, and connective tissue fibers form a “battlefield” under the skin and mucous membranes where immune cells can be quickly mobilized against disease agents ○ Movement - Bones provide the lever system for body movement, cartilages are involved in movement of the vocal cords, and cartilages on bone surfaces ease joint movement ○ Storage - Fat is the body’s major energy reserve, the bones are reservoirs of calcium and phosphorus that can be drawn upon when needed ○ Heat production - Metabolism of brown fat generates heat in infants and children ○ Transport - Blood transports gases, nutrients, wastes, hormones, and blood cells

5.3b Fibrous Connective Tissue ● The MOST diverse type of tissue ● Nearly all connective tissue contains fibers ● Components of Fibrous Connective Tissues: ○ Fibroblasts - Produce fibers and ground substances that form the matrix of the tissue ○ Macrophages - Large phagocytic cells that wander and destroy bacteria and other foreign particles, they also rid the body of dead or dying cells

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■ The reason our immune system is activated ○ Leukocytes (White Blood Cells) - Travel briefly in the bloodstream to where they are needed and attack bacteria and foreign agents ○ Plasma Cells - Cells that synthesize antibodies, only seen in the wall of the intestines and inflamed tissue ○ Mast Cells - The blood flow regulation cells; creates heparin that inhibits blood clotting, and histamine that increases blood flow by dilating blood vessels ○ Adipocytes - Fat cells that create adipose tissue Types of Fibers ○ Collagenous Fibers - Made of collage and are tough and flexible. Body’s most abundant protein. The base of animal products such as : gelatin, leather, and glue ○ Reticular Fibers - Thin collagen fibers that are coated with glycoproteins. Forms a sponge like framework for organs like the spleen and lymph nodes ○ Elastic Fibers - Thinner than collagenous fibers, made from elastin and coated with a glycoprotein. It’s structure allows it to stretch and recoil Ground Substance: The empty space that is usually gelatinous/rubbery consistency and can absorb compressive forces Glycosaminoglycan (GAG): A long polysaccharide composed of unusual disaccharides called amino sugars and uronic acids ○ Negatively charged and attract sodium and potassium ions ○ They can absorb and retain water ○ The most common GAG is Chondroitin Sulfate Proteoglycan: A gigantic molecule shapes like a bottle brush with a central core of protein and bristlelike outgrowths composed of GAGS Adhesive Glycoproteins: Protein-carbohydrate complexes that bind plasma membrane proteins to extracellular collagen and proteoglycans Types of Fibrous Connective Tissue: ○ Areolar Tissue - Loosely organized fibers, abundant blood vessels, and a lot of seemingly empty space. Found in almost every part of the body ○ Reticular Tissue - Mesh of reticular fibers and fibroblasts ■ It is the framework of the lymph nodes, spleen, thymus, and bone marrow ○ Dense Regular Connective Tissue - Closely packed collagen fibers that are parallel to one another ■ Found in tendons and ligaments ○ Dense Irregular Connective Tissue - Thick bundles of collagen and relatively little room for cells and ground substance, collagen runs in completely random directions The vocal cords and some spinal ligaments are made of a dense regular connective tissue (Elastic Tissue)

5.3c Adipose Tissue ● Adipose tissue is also known as fat ○ Adipocytes are the dominant cell type ● There are two kinds of fat in humans: ○ White/Yellow - More abundant and is the most significant adipose tissue of the adult body, it provides insulation and anchors/cushions organs ○ Brown - Mainly found in fetuses, infants, and children, but adults have small deposits of brown fat, it is a heat-generating tissue

5.3d Cartilage ● A relatively stiff connective tissue with a flexible rubbery matrix ● Produced by cells called Chondroblasts that secrete the matrix and surround themselves with it until they become trapped in little cavities (Lacunae) ● Once enclosed in lacunae the cells are called Chondrocytes ● Cartilage is devoid of blood capillaries, this means nutrition and waste removal rely heavily on solute diffusion through the stiff matrix ● Types of Cartilage: ○ Hyaline Cartilage - Clear and glassy in appearance, and stems from the usually invisible fineness of its collagen fibers ○ Elastic Cartilage - Named for its conspicuous elastic fibers ○ Fibrocartilage - Named for its coarse, readily visible bundles of collagen ● Elastic cartilage and most hyaline cartilage are surrounded by a sheath of dense irregular connective tissues (Perichondrium)

5.3e Bone ● AKA Osseous Tissue is a hard, calcified connective tissue that composes the skeleton ● Bone has two meanings in anatomy: ○ 1. An entire organ - such as the femur and mandible ○ 2. Just the osseous tissue ● Bones are composed of osseous tissue, cartilage, bone marrow, dense irregular connective tissue, and other tissue types ● 2 forms of osseous tissue: ○ 1. Spongy bone - Fills the heads of the long bones and forms the middle layer of flat bones such as the sternum and cranial bones ○ 2. Compact (dense) bones - A denser calcified tissue with no spaced visible to the naked eye ■ Covers spongy bone so it is not exposed

5.3f Blood ● A fluid connective tissue that travels through tubular blood vessels ○ Primary function is to transport cells and dissolved matter from place to place

● Blood is composed of Blood Plasma and it’s Formed Elements (cellular components that are collectively called this) ● Formed Elements: ○ Erythrocytes - Red blood cells (RBCs) ○ Leukocytes - White blood cells (WBCs) ○ Platelets - Small cell fragments scattered amid the blood cells

5.4 Nervous and Muscular Tissues - Excitable Tissues 1. Explain what distinguishes excitable tissues from other tissues 2. Name the cell types that compose nervous tissue 3. Identify the major parts of a nerve cell 4. Visually recognize nervous tissue from specimens or photographs 5. Name the three kinds of muscular tissue and describe the differences between them 6. Visually identify any type of muscular tissue from specimens or photographs

● Excitability is a characteristic of all living cells but is seen in the highest degree in nervous and muscular tissues ● The basis for their excitation is an electrical charge difference (voltage) or the membrane potential ● Nervous and muscular cells respond quickly to outside stimuli by means of changes in membrane potential

5.4a Nervous Tissue ● Specialized for communication by means of electrical and chemical signals ● Consists of neurons (nerve cells), and a much greater number of neuroglia (the protectors and assistant of neurons) ● Each neuron has a prominent neurosoma (cell body) that houses the nucleus and most other organelles ● Dendrites extend from the neurosoma and receive signals from other cells and conduct messages to the neurosoma ● Axons (nerve fibers) send outgoing signals to other cells (they are much longer structures) ● Nervous tissue is found in the brain and spinal cord, nerves, and ganglia

5.4b Muscular Tissue ● Specialized to contract when stimulated, and can exert physical force on other tissues, organs, or fluids

● Three types of muscular tissue: ○ 1. Skeletal - Consist of muscle fibers and is mainly attached to bones (exceptions

being the tongue, upper esophagus, some facial muscles, and some sphincter muscles) ○ 2. Cardiac - Limited to the heart, is also striated, consists of cardiomyocytes (cardiac cells) rather than fibers. They contain only one nucleus. ■ Cardiac muscles are considered involuntary because it is not usually under conscious control ○ 3. Smooth - Lacks striations and is involuntary. The largest amounts of visceral muscle is found in the walls of the digestive system, respiratory, and urinary tracts; the blood vessels; the uterus; and other viscera ■ Very important in controlling blood pressure and flow

5.5 Cellular Junctions, Glands, and Membranes 1. Describe the junctions that hold cells together and tissues together 2. Describe or define different types of glands 3. Describe the typical anatomy of a gland 4. Name and compare different modes of glandular secretion 5. Describe the types and composition of the body’s membrane

5.5a Cellular Junctions ● Most cells (minus blood cells, macrophages, and metastatic cancer cells) must be anchored to each other and to the matrix if they are to grow and divide normally ● The connections between one cell and another is called cellular junctions ○ This allows the cell to resist stress, communicate with each other, and control the movement of substances through tissues ● Without them the cardiac muscles would pull apart when they contracted, and every swallow of food would scrape away the lining of your esophagus ● Tight Junctions: ○ Completely encircles an epithelial cell near its apical surface and joins it tightly to the neighboring cells ○ The plasma membrane of two adjacent cells come very close together and are linked by a transmembrane cell-adhesion protein ○ Ex. In the stomach and intestines, tight junctions prevent digestive juices from seeping between epithelial cells and digesting the underlying connective tissue ■ They also help to keep bacteria from invading the tissues ● Desmosomes: ○ A patch that holds cells together somewhat like the snape of a pair of jeans ○ They are not continuous and cannot prevent substances from passing around them and going between the cells ○ They instead serve to keep the cells together and from being pulled apart ○ They can be found in → Epidermis, the epithelium of the uterine cervix, other epithelia, and cardiac muscle

● Gap Junctions: ○ Gap junctions allow electrical excitation to pass directly from cell to cell so that the cells contract in unison ○ Formed by a connexon

5.5b Glands ● A cell or organ that secretes substances for use elsewhere in the body or for elimination as waste ● The gland product may be something synthesizes by its cells or something removed from the tissues amd modified by the gland ● Secretion: Useful to the body (enzyme or hormone) ● Excretion: A waste product (urine and bile) ● Glands are mostly composed of epithelial tissue ● Endocrine and Exocrine Glands: ○ Exocrine Glands - Usually maintain their contact with the surface by way of a duct ○ Endocrine Glands - Lose contact with the surface and have no ducts ■ They do however have a high density of blood capillaries and secrete their products directly into the blood ■ Include: Thyroid, pituitary, and adrenal glands

5.5c Membranes ● May be composed of epithelial tissues only; connective tissue only; or epithelial, connective, and muscular tissue ● Cutaneous Membrane: The largest membrane of the body (more simply- the skin) ● Two kinds of membrane: ○ Mucous - lines passages that open to the exterior environment; the digestive, respiratory, urinary, and reproductive tracts ■ Consists of 3 layers (1. Epithelium 2. Areolar connective tissue 3. Smooth muscle) ○ Serous - Composed of a simple squamous epithelium resting on a thin layer of areolar connective tissue ■ Produce a watery serous fluid ■ Lines the insides of the digestive tract...