Chapter 4: Tissue Level of Organization Flashcards
name the four basic types of tissues that make up the human body and state the characteristics of each.
epithelial tissue – covers body surfaces, lines hollow organs, body cavities and ducts. Also forms glands. Allows the body to interact with both internal and external environments.
connective tissue – protects and supports the body and its organs. Various types of connective tissues bind organs together, store energy reserves as fat, help provide the body with immunity to disease-causing organisms
muscular tissue – composed of cells specialized for contraction and generation of force. In the process, muscular tissue generates heat, warming the body
nervous tissue – detects changes in a variety of conditions inside and outside the body, responds by generating nerve action potentials that activate muscle contractions and gland secretions.
describe the structure and functions of the five main types of cell junctions.
Cell junctions: contact points b/w the plasma membrane of cells.
1) tight junction – consist of web-like strands of transmembrane proteins that fuse together the outer surfaces of adjacent plasma membranes to seal off passageways between adjacent cells. Ex: epithelial tissue that lines stomach, intestines, urinary bladder. Inhibit passage of substances between cells, prevent contents of organs from leaking into blood or surrounding tissues.
2) adherens junction – contain plaque. Joined by cadherins. Often form extensive zones called adhesion belts. Encircle the cell like a belt on waist. Help epithelial surfaces resist separation during contractile activities. Ex: food moving through intestines
plaque – dense layer of proteins on the inside of the plasma membrane that attaches to membrane proteins and to microfilaments of the cytoskeleton.
Cadherins – transmembrane glycoproteins that insert into the plaque from the opposite side of the plasma membrane, partially cross the intercellular space and connects to cadherins of an adjacent cell.
3) Desmosome – also contain plaque and have cadherins that extend into the intercellular space between adjacent cell membranes and attach cells to one another. However, the plaque attaches to intermediate filaments of the cytoskeleton and extend from one side of the cell to desmosomes on the other side of the cell. Contributes to stability of cells and tissues. Ex: Common in epidermis and cardiac muscle cells. Prevent cells from separating under tension/during contraction
4) Hemidesmosome – do not link adjacent cells. Connect the cell to the basement membrane. Contain integrins which attach to intermediate filaments and on the outside, integrins attach to laminin.
Integrins – transmembrane glycoprotein in plasma membranes that functions in cell adhesion. Present in hemidesmosomes which anchor cells to basement membrane. Also mediate adhesion of neutrophils to endothelial cells during emigration.
5) gap junction – tiny fluid filled tunnels called connexons formed by connexins connect neighboring cells. Plasma membranes not fused; very narrow intercellular gap. Allows ions and small particles to diffuse from cytosol of one cell to another. Allow communication between cells, rapid spread of nerve or muscle impulses. Transfer of nutrients in avascular tissues (lens and cornea of eye)
Connexins – membrane proteins that form tiny fluid-filled tunnels called connexons
state the main differences between epithelial and connective tissues.
Connective: large amount extra cellular space, widely scattered cells , significant network of blood vessels
Epithelial: little or no extracellular matrix, tightly packed cells, no blood vessels, almost always forms surface layers and is not covered by another tissue
Epithelial tissue is always found next to connective tissue, makes exchanges for nutrients and wastes possible for epithelial tissue
describe the general features of epithelial tissue.
Many cells tightly packed together, avascular. Includes covering and lining epithelium and glandular epithelium. Arranged in sheets and attached to a basement membrane, has a nerve supply, high cell division rate gives it a high capacity for renewal, can be stratified, pseudostratified or simple. Can be squamous (flat), cuboidal, columnar (rectangular) or transitional (variable).
list the location, structure, and function of each different type of epithelial tissue.
Simple Squamous Epithelium
Structure - Single layer of flat cells
Location –Heart and blood vessels, lines thoracic and abdominopelvic cavities and covers organs within them Function – Filtration and diffusion
Simple Cuboidal Epithelium
Structure – Single layer of cube shaped cells
Location – Covering the ovaries, in the kidneys and eyes and lining some glandular ducts Function – Secretion and absorption
Non-Ciliated Simple Columnar Epithelium
Structure – Single layer of non-ciliated rectangular cells
Location – Lines most of the GI tract
Function – Perform absorption and secrete mucus
Ciliated Simple Columnar Epithelium
Structure – Single layer of ciliated rectangular cells
Location – Few portions of the upper respiratory tract
Function – Moves foreign particles trapped in mucus out of the respiratory tract
Pseudostratified Columnar Epithelium
Structure – Contains goblet cells, non-ciliated variety has no goblet cells
Location – Lines most of the upper respiratory tract, non-ciliated variety lines ducts of many glands, the epididymis and part of male urethra
Function – Absorption and protection, ciliated variety moves mucus in the respiratory tract
Stratified Squamous Epithelium
Structure – Consists of several layers of cells, are flat
Location – Nonkeratinized lines the mouth, keratinized variety form the epidermis
Function -
Stratified Cuboidal Epithelium
Structure – Cells at the apical layer are cube-shaped
Location – Found in adult sweat glands and in a portion of the male urethra
Function – Protects and provides limited secretion and absorption
Stratified Columnar Epithelium
Structure – Cells at the apical later have a columnar shape
Location – Portion of the male urethra and in large excretory ducts of some glands
Functions – Protection and secretion
Transitional Epithelium
Structure – Consists of several layers of cells, appearance varies with the degree of stretching
Location – Lines the urinary bladder
Function -
explain the general features of connective tissue.
Most abundant in the body, consists of relatively few cells, abundant extracellular matrix of ground substance and protein fibers, does not usually occur on free surfaces, has a nerve supply and is highly vascular, cells and derived primarily from mesenchymal cells.
Cells within a matrix
Fibers – 3 types of fibers embedded in extracellular matrix between cells.
Function: strengthen and support connective tissues
a. ) collagen fiber
Very strong. Resist pulling forces (tension) but not stiff, allowing flexibility. Properties vary from tissue to tissue. Ex. Collagen fibers in cartilage surrounded by more water than in bone, giving cartilage a cushioning effect. Often occur in parallel bundles (dense regular connective tissue)Bundle arrangement adds great tensile strength to tissue.Chemical arrangement: consist of the protein collagen, most abundant protein in body (25%) Collagen fibers found in most types of connective tissue, especially bone, cartilage, tendons, and ligaments
b.) elastic fiber
Smaller in diameter than collagen fibers. Branch and join to form a fibrous network within a connective tissueConsists of protein elastin surrounded by glycoprotein fibrillin, which adds strength and stability Unique molecular structure: can stretch up to 150% of relaxed state without breaking. Elasticity – ability of elastic fibers to return to original shape after being stretched.Found in skin, blood vessel walls, lung tissue
c. reticular fiber
Consist of collagen arranged in fine bundles with a coating of glycoprotein. Provide support in the walls of blood vessels and form a network around cells in some tissues (Ex areolar connective tissue, adipose tissue, nerve fibers, smooth muscle tissue)Produced by fibroblasts. Much thinner than collagen fibers. Form branching networks Provide support and strength.
describe the structure, location, and function of the various types of connective tissue.
Bone, Blood, Cartilage, Lymph - binding and support, protection, insulation, transportation (blood)
Types of Cells:
Fibroblasts – Secrete extracellular matrix
Macrophages – Perform phagocytosis
Plasma Cells – Secrete antibodies
Mast Cells – Produce Histamine
Adipocytes – Store fat
WBC – Responds to infections
Loose ConnectiveTissue
Includes aerolar, adipose, and reticular connective tissue
Areolar Connective TissueStructure – Made of Collagen, Elastic and Reticular fibers. Several types of cells and semifluid ground substance
Function – Secretion and absorption
Location – Found in the Sub-Q layer, mucous membranes and around blood vessels, nerves and body organs
Adipose Tissue
Structure – Consists of adipocytes which store triglycerides
Function – Generates heat (Brown adipose tissue)
Location – Found in the Sub-Q layer, around organs and in yellow bone marrow
Reticular Connective Tissue
Structure - Consists of reticular fibers and reticular cells
Function -
Location – Liver, spleen, and lymph nodes
Dense Regular Connective Tissue
Forms tendons most ligaments and aponeuroses, Consists of parallel bundles of collagen fibers and fibroblasts
Dense Irregular Connective Tissue
Consists of collagen fibers and a few fibroblasts, found in fasciae, the dermis of the skin and a membrane capsules around organs
Elastic Connective Tissue Consists of branching elastic fibers and fibroblasts, found in walls of large arteries,lungs, trachea and bronchial tubes Cartilage Contains chondrocytes and has a rubbery extracellular matrix containing collagen and elastic fibers
Chondrocytes
A cell which has secreted he matrix of cartilage and become embedded in it Hyaline cartilage Gel like ground substance and appears bluish white in the body, is found in embryonic skeleton at the end of bones in the nose and in the respiratory structures. Flexible, allows movement, provides support, and is usually surrounded by perichondrium
Fibrocartilage Found in the pubic symphysis, intervertebral discs and menisci (cartilage pads) of the knee joints. Contains chondrocytes scattered among clearly visible bundles of collagen fibers
Elastic Cartilage
Maintains the shape of organs such as the epiglottis of the larynx, auditory tubes and external ear. Chondrocytes and located within a threadlike network of elastic and it has a perichondrium
Bone Tissue or Osseous Tissue
Extracellular matrix of mineral salts and collagen fibers that contribute to the hardness of bone and osteocytes that are located in the lacunae.
Supports and protects the body, surface area for muscle attachment, body movement, stores minerals, houses blood forming tissue
Osteon or Haversian SystemBasic unit of structure in adult compact bone, central haversian canal with its concentrically arranged lamellae, lacunae, osteocytes and canaliculi
Osteocytes
Mature bone cell that maintains the daily activity of bone tissue
Blood Tissue
Blood plasma and formed elements – RBC, WBC, and platelets, transport O2 and CO2 carry on phagocytosis, participate in allergic reactions provide immunity and clot blood Plasma Extracellular fluid found in blood vessels; blood minus the formed elements
describe the properties of the various types of membranes
Membrane
Lipid bilayer which surrounds enclosed spaces and compartments, essential for effective separation of a cell or organelle
define a membrane.
Flat sheets of pliable tissue that cover or line a part of the body. Majority consist of an epithelial layer and an underlying connective tissue layer.
describe the classification of membranes.
1) Mucous Membrane or Mucosa
Lines cavities open to the exterior
2) Serous Membrane or Serosa
Lines closed cavities and cover organs in them, consist of a parietal and visceral layer
3) Cutaneous Membrane or Skin
Covers entire body and consists of a superficial epidermis (epithelium) and a deepdermis (connective tissue)
4) Synovial Membrane
Lines joint cavities and consists of areolar connective tissue does not have an epithelial layer
describe the general features of muscular tissue
Consists of cells called muscle fibers of myocytes for contraction, provides motion,maintenance of posture heat production and protection, skeletal attaches to boneis striated and voluntary, Cardiac found in the walls of hollow internal structure is nonstriated and involuntary, Smooth is found in the GI tract and bladder and is nonstriated and involuntary.
describe the structural features and functions of nervous tissue.
Composed of neurons and neuroglia, neurons respond to stimuli into electrical signals called nerve action potentials and conduct nerve impulses to other cells. Most neurons consist of a cell body and two types of processes dendrites and axons.
explain the concept of electrical excitability.
Electrical excitability is the ability to respond to certain stimuli by producing electrical signals such as action potentials
Because neurons and muscle fibers exhibit electrical excitability, they are considered excitable cells
