Chapter 4 - The Tissue Level of Organization Flashcards
Define tissue
A group of cells that usually have a common origin in an embryo and function together to carry out specialized activities
Define histology
The science of the study of tissues
Epithelial tissue
Covers body surfaces and lines hollow organs, body cavities, and ducts; it also forms glands. Allows body to interact with 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, and help provide the body with immunity to disease-casuing organisms.
Muscular tissue
is composed of cells specialized for contraction and generation of force. Generates heat.
Nervous tissue
Detects changes in a variety of conditions inside and outside the body and responds by generating electrical signals called nerve action potentials (nerve impulses) that activate muscular contractions and glandular secretions.
Cell junction
contact points between the plasma membranes of tissue cells
Tight Junction
weblike strands of transmembrane proteins that fuse together the outer surfaces of adjacent plasma membranes to seal off passageways between adjacent cells. Prevent contents of organs like bladder from leaking into blood
Adherens junction
Contain plaque, a dense layer of proteins on the inside of the plasma membrane that attaches both to membrane proteins and to microfilaments of the cytoskeleton. Transmembrane glycoproteins called cadherins join the cells.
Often form Adhesion belts. Help resist seperation
Desmosome
contain plaque and have transmembrane glycoproteins that attach cells to one another, attaches using elements of the cytoskeleton aka intermediate filaments (made of keratin) preventing seperation
Hemidesmosome
Integrins attach to intermediate filaments, on outside attach to laminin to anchor cells to each other and the basement membrane
Gap junction
connexins connect neighboring cells. Through connexons ions and small molecules can diffuse from the cytosol of one cell to another.
Pathologist
Physician who examines cells and tissues to help other physicians make accurate diagnoses
General features of epithelial tissue
Many cells tightly packed together with little or no extracellular matrix. No blood vessels. Almost always forms surface layers, not covered by another tissue (except lining of blood vessels) Always found immediately adjacent to blood vessel-rich connective tissue.
Apical
Apical (free) surface faces the body surface, cavity, lumen or tubular duct that receives cell secretions. May contain cilia or microvilli.
Basement membrane
thin extracellular layer that consists of two layers, basal lamina and reticular lamina. Attaching to and supporting overlying epithelial tissue. Form a surface along which epithelial cells migrate during growth or healing, restrict passage of large molecules, and filter blood in kidneys.
Covering/Lining epithelium
forms outer covering of skin and some internal organs. Inner lining of blood vessels, ducts, body cavities, and interior of the respiratory, digestive, urinary, and reproductive systems.
Glandular Epithelium
makes up the secreting portion of glands such as the thyroid gland, adrenal glands, and sweat glands.
Lateral surface
may contain tight junctions, adherens junctions, desmosomes, gap junctions.
Basal surface
deepest layer of epithelial cells adhere to extracellular materials such as basement membrane.
Main roles of epithelial tissue
protection, filtration, secretion, absorption, excretion
Structure location and function of simple squamous epithelium
Single layer of flat cells, flattened oval nucleus in centre.
lines cardiovascular and lymphatic system known as endothelium. OR form epithelial layer of serous membranes known as mesothelium. Air sacs of lungs, glomerular capsule of kidneys, inner surface of tympanic membrane.
Sites of filtration, diffusion, secretion
Structure location and function of simple cuboidal epithelium
single layer of cube shaped cells Surface of ovary, anterior surface of capsule lens of eye, pigmented epithelium at posterior surface of retina, lines kidney tubules, secretion and absorption
Structure location and function of simple columnar epithelium
ciliated or nonciliated. single layer contains columnar epithelial cells with microvili at apical surafce and goblet cells.
Lines gastrointestinal tract, ducts of many glands and gullbladder.
Secretiona nd absorption.
Ciliated: lines some bronchioles, uterine tubes, central canal of spinal cord, ventricles of brian, the cilia beat in unison moving mucus and foreign particles toward throat.
Structure location and function of pseudostratified columnar epithelium
Cells attached to basement membrane. Lines airways, nonciliated ducts of glands, epidymis and male urethra. Traps foreign particles, nonciliated for absorption and protection
Structure location and function of stratified squamous epithelium
two or more layers of cells. keratinized for superifical layer of skin, nonkeratinized lines wet surphases. Protection against abrasion, water loss, UV, foreign invasion
Structure location and function of stratified cuboidal epithelium
two or more layers of cells, apical are cube-shaped. Ducts of sweat glands, esophageal glands, male urethra. Protection, limited secretion and absorption
Structure location and function of stratified columnar epithelium
shortened irregularly shaped cells, apical columnar. Part of urethra, large excretory ducts. Protection and secretion
Structure location and function of transitional epithelium
Stretched becomes flatter. Elasticity,bladder, portions of ureters and urethra. allows stretching and protection
Microvilli
fingerlike cytoplasmic projections, increase surface area of plasma membrane
Goblet cells
modified columnar epithelial cells that secrete mucus, a slightly sticky fluid, at their apical surfaces. Before release, mucus accumulates in upper portion of cell, causing it to bulge and making the whole cell resemble a goblet or wine glass.
Arrangement of cells in simple epithelium
one layer, squareish nucleus centre
Arrangement of cells in pseudostratified epithelium
stretched columnar nucleus within
Arrangement of cells in stratified epithelium
attached to basement, cubodial,
Glandular epithelium
Secretion, accomplished by glandular cells that often lie in clusters deep to the covering and lining epithelium
Gland
May consist of a single cell or a group of cells that secrete substances into ducts (tubes) onto a surface or into the blood.
Endocrine gland
Secretions are hormones, enter interstitial fluid and then diffuse into bloodstream.
Exocrine gland
Secrete their products into ducts that empty onto the surface of a covering and lining epithelium such as the skin surface or the lumen of a hollow organ.
Unicellular exocrine glands
Single celled. includes goblet cells.
Multicellular exocrine glands
composed of many cells that form a distinctive microscopic structure or macro- scopic organ. Examples include sudoriferous (sweat), sebaceous (oil), and salivary glands.
Classified by branched or unbranched
Simple exocrine glands
Unbranched
Compound exocrine glands
Branched
Acinar exocrine glands
Rounded secretory portions
Tubuloacinar exocrine glands
Both tubular and more rounded secretory parts.
Merocrine gland
Salivary glands and pancreas. Golgi complex to Secretory vesicle
Apocrine gland
Secretory product accumulates at apical surface, portion pinches off by exocytosis. Repairs and repeats. Secretion of milk.
Holocrine gland
Accumulate secretory product in cytosol, ruptures. Lots of lipids, is replaced. Sebaceous glands of skin.
Connective tissue
Most abundant tissue. Binds together, supports, strengthens, protects, insulates, compartmentalizes, transport system, location of energy reserve, main source of immune responses.
Extracellular matrix
material between widely spaced cells. Structure determines tissue’s qualities.
Fibroblast
Large, flat, branching, secret fibers and certain components of ground substance of exma
Macrophage
develop from monocytes. irregular shape, short branches. Engulf bacteria. Fixed or wandering.
Plasma cell
small cells, develop from B lymphocyte. Secrete antibodies, most in connective tissue, gastrointestinal and respiratory tracts. (also salivary glands, lymph nodes, spleen, red bone marrow)
Mast cell
abundant alongside blood vessels. produce histamine, dilates small blood vessels in inflammatory response.
Adipocyte
store fats found deep in skin and around heart and kidneys.
Leucocytes
Not found in but migrate to connective tissue from blood.
Connective tissue extracellular matrix
Ground substance and fibers
Ground substance
is the component of a con- nective tissue between the cells and fibers. The ground substance may be fluid, semifluid, gelatinous, or calcified. It supports cells, binds them together, stores water, and provides a medium for ex- change of substances between the blood and cells. It plays an active role in how tissues develop, migrate, proliferate, and change shape, and in how they carry out their metabolic functions.
Ground substance contains water and an assortment of large organic molecules, many of which are complex combinations of polysaccharides and proteins.
Fibers
strengthen and support connective tissues.
Collagen fiber
Strong to resist tension, but not stiff.
Elastic fiber; elasticity
Smaller, branch and join together to form a fibrous network. strength and stability. Stretch 150% of relaxed length, but return to shape
Reticular fiber; stroma
Collagen arranged in fine bundles with coating of glycoprotein to provide support in walls of blood vessels or network around cells of some tissues.
Stroma=supporting framework
embryonic connective tissues: mesenchyme
irregularly shape mesenchymal cells embedded in semifluid ground substance that contains delicate reticular fibers.
Under skin, along developing bones of embryo. Forms types of connective tissue
embryonic connective tissues: mucous connective tissue
widely scattered fibroblasts embedded in viscous, jellylike ground substance that contains fine collagen fibers. Umbilical cord of fetus. Support
Loose: areolar connective tissue
Consists of fibers arranged randomly, several kinds of cells embedded in semifluid ground substance.
In and around every body structure “packaging” Strength, elasticity, support
Loose: adipose tissue
Cells derived from fibroblasts, storage of fats, weight gain = more adipose tissue and new blood vessels, higher blood pressure. Brown in infants and adult because rich blood supply.
Reduces heat loss, energy reserve, supports, protects.
Loose: reticular connective tissue
Fine interlacing network of reticular fibers. Stroma of liver, spleen, lumph nodes, red bone marrow, around blood vessels and muscles. Forms stroma of organs, binds smooth muscle tissue cells. filters and removes worn out blood cells in spleen and microbes in lymph nodes.
dense regular connective tissue
Forms tendons. Strong attachments.
dense irregular connective tissue
Made up of collagen fibers, occurs in sheets. Provides tensile (pulling) strength in many directions.
elastic connective tissue
elastic fibers with fibroblasts between, yellowish. lung tissue, stretching of various organs. (like penis or vocal cords)
Cartilage
consists of a dense network of collagen fibers and elastic fibers firmly embedded in chondroitin sulfate, a gel-like component of the ground substance. Cartilage can endure considerably more stress than loose and dense connective tis- sues. The strength of cartilage is due to its collagen fibers, and its resilience (ability to assume its original shape after deformation) is due to chondroitin sulfate.
Chondrocyte
Cells of mature cartilage
Lacunae
spaces, little lakes, between chondrocytes in exma
Perichondrium
dense irregular connective tissue, surrounds most cartilage and contains blood vessels and nerves, source of new cartilage cells. heals poorly
Hyaline cartilage
resilient gel. most abundant cartilage, provides smooth surfaces movement at joints, flexibility and support but is weak
Fibrocartilage
has chondrocytes, bundles of callagen. Pubic symphysis, menisci, support and join, strongest
Elastic cartilage
chondrocytes in threadlike network. Lid on top of larynx, auditory tubes, provides strength and elasticity
Interstitial growth
Growth within. Rapid in size like bread rising, young and pliable
Appositional growth
outer surface growth. Differentiation.
Osteon or harversian system
basic unit of compact bone
Lamellae
are concentric rings of extracellular matrix that consist of mineral salts (mostly calcium and phosphates), which give bone its hardness and compressive strength, and collagen fibers, which give bone its tensile strength. The lamellae are responsible for the compact nature of this type of bone tissue.
Canaliculi
networks of minute canals containing the processes of osteocytes. Provide routes for nutrients to reach osteocytes and for wastes to leave them.
Central canal (harversian canal)
Contains blood vessels and nerves
Spongy bone
Lacks osteons, consists of columns of bone called trabeculae, spaces between filled with red bone marrow.
Blood tissue
A liquid connective tissue has a liquid as its extracellular matrix.
Plasma
is a pale yellow fluid that consists mostly of water with a wide variety of dissolved substances— nutrients, wastes, enzymes, plasma proteins, hormones, respiratory gases, and ions.
Red blood cell
transport oxygen to body cells and remove some carbon dioxide from them
White blood cell
are involved in phagocytosis, im- munity, and allergic reactions.
Platelet
participate in blood clotting.
Lymph
extracellular fluid that flows in lymphatic vessels. composition varies.
Membrane
Flat sheets of pliable tissue that cover or line a part of the body.
Epithelial membrane
an epithelial layer and an underlying connective tissue layer
Mucous membrane
lines a body cavity that opens directly to exterior. Line entire digestive, respiratory and reproductive tracts. Barrier. Secrets enzymes for digestion and food/fluid absorption.
Lamina propria
The connective tissue layer of a mucous membrane is areolar connective tissue, supports epithelium, binds to underlying structure providing flexibility and protection. Oxygen and nutrients diffuse from lamina propria to covering epithelium, co2 and waste opposite.
serous membrane or serosa
Lines body cavity, covers organs within cavities. Parietal layer and visceral layer. Secrets serous fluid, a watery lubricant that allows organs to glide easily over one another or to slide against the walls of cavities.
Parietal and visceral layers
Parietal - attached to and lining the cavity wall.
Visceral- covers and adheres to organs within the cavity
Pleura, pericardium, peritoneum
serous membrane lining the thoracic cavity and covering the lungs is the pleura. The serous membrane lining the heart cavity and covering the heart is the pericardium. The serous membrane lining the abdominal cavity and covering the abdominal organs is the peritoneum.
cutaneous membrane or skin
Covers surface of body.
Epidermis
Keratinized stratified squamous epithelium, protects underlying tissues.
Synovial membrane
line cavities of freely movable joints.
Synovial membrane
Synovial membranes are composed of a discontinuous layer of cells called synoviocytes
Synovial fluid
Synovial fluid lubricates and nourishes the cartilage covering the bones at movable joints and contains macrophages that remove microbes and debris from the joint cavity.
Skeletal muscle tissue
Voluntary. Long, cylindrical striated fibers. Attached to bones by tendons. motion, posture, heat production, protection
Cardiac muscle tissue
Branched, striated fibers. heart wall, pumps blood
Intercalated disc
transverse thickenings of plasma membrane attaching cardiac muscle tissue
Smooth muscle tissue
involuntary. iris of eyes, airways to lungs,. Motions.
Nervous tissue
consists of only two principal types of cells: neurons and neuroglia.
Neuron
or nerve cells, are sensitive to various stimuli. They convert stimuli into electrical signals
Nerve action potentials
electrical signals produced by neurons
Cell body
contains the nucleus and other organelles
Dendrites
tapering, highly branched, usually short cell processes. receiving or input portion of a neuron
Axon
single, thin, cylindrical process. output portion of neuron .
Excitable cells and electrical excitability
Neurons and muscle fibers are excitable, the ability to respond to stimuli by producing electrical signals.
Neurotransmitter
chemicals released by neurons for communication
SLE / lupus
chronic inflammatory disease of connective tissue. painful joints, low grade fever, fatigue, mouth ulcers, weight loss, enlarged lymph nodes and spleen, sensitivity to sunlight. butterfly rash
