Chapter 4 Flashcards
Tissues
Groups of cells similar in structure that perform common or related function
Examples of Nervous Tissues
Brain, Spinal Cord, Nerves
Examples of Muscles Tissues
Skeletal , Cardiac, Smooth
Examples of Epithelial Tissues
Lining of digestive tract organs and other hollow organs, skin surface
Examples of Connective Tissue
Bones, Tendons, Fat and other soft padding
Epithelial Tissues (Epithelium)
Forms boundaries
Two main types (by location)
-Covering and lining epithelium
-Glandular epithelium
Epithelial Functions
Protection Absorption Filtration Excretion Secretion Sensory Reception
Characteristics of Epithelial
Orientation Specialized contacts Supported by connective tissues Avascular, but innervated Can regenerate
Orientation of Epithelial Tissue
2 surfaces
-Apical- upper, free surface, exposed to exterior or cavity
-Basal- lower, attached
Both surfaces differ in structure and function
Apical Surface
Smooth and slick
Most have microvilli to increase surface area
Some have cilia
Basal Lamina
Adhesive sheet
Scaffolding for cell migration in wound repair
Specialized Contacts of Epithelial Tissue
Form continuous sheets
Specialized contacts bind adjacent cells
-Tight Junctions
-Desmosomes
Support of Epithelial
Connective Tissue -Network of collage Basement Membrane -Basal lamina and reticular lamina -Resists stretching and tearing -Defines epithelial boundary
Avasularity with Epithelial Tissue
No blood vessels
Supplied by nerve cells
Regeneration in Epithelial Tissue
Highly regenerative
Stimulated by loss of apical-basal and lateral contacts
Classification of Epithelia
All have 2 names
One indicates number of cell layers
-Simple epithelia- single layer of cells
-Stratified epithelia- two or more layers of cells
–Shape can change in different layers
One indicates shape of cell
-Squamous
-Cuboidal
-Columnar
In Stratified epithelia, epithelia is classified by cell shape in apical layer
Squamous Cells
- Flattened and scalelike
- Nucleus flattened
Cuboidal Cells
- Boxlike
- Nucleus elongated
Columnar Cells
- Tall; column shaped
- Nucleus elongated
Simple Epithelia
Absorption
Secretion
Filtration
Stratified Epithelial Tissues
Two or more cell layers
Regenerated from below
More durable than simple epithelia
Protection is major role
Stratified Squamous Epithelium
Most widespread of stratified epithelia Free surface squamous Deeper layers cuboidal or columnar Located for wear and tear Varied viability
Stratified Cuboidal Epithelium
Quite rare
Location- some sweat and mammary glands
Typically 2 cell layers thick
Only apical layer columnar
Transitional Epithelium
Forms lining of hollow urinary organs
Basal layer cells are cuboidal or columnar
Ability to change shape with stretch
Apical cells vary in appearance
Glandular Epithelia
Gland
-One or more cells that makes and secretes an aqueous fluid called a secretion
Classified by
-Site of product release
–endocrine or exocrine
Relative number of cells forming the gland
-unicellular (e.g. goblet cells) multicellular
Endocrine Glands
Ductless glands
-Secretions not released into a duct
Secrete (by exocytosis) hormones that travel through lymph or blood to their specific target organs
Target organs respond in some characteristic way
Exocrine Glands
Secretions released onto skin or into body cavities
More numerous than endocrine glands
Secrete products into ducts
Examples include mucous, sweat, oil, and salivary glands
Unicellular Exocrine Glands
The only important unicellular glands are mucous cells and goblet cells
Found in epithelial linings of intestinal and respiratory tracts
All produce a substance that dissolves in water to form mucus
Multicellular Exocrine Glands
Multicellular exocrine glands are composed of a duct and a secretory unit
Surrounded by supportive connective tissue
-Supplies blood and nerve fibers
-Extends into and divides glands into lobes
Connective Tissue
Most abundant and widely distributed of primary tissues 4 main classes -Connective Tissue Proper -Cartilage -Bone -Blood
Major Functions of Connective Tissue
Binding and Support Protecting Insulating Storing reserve fuel Transporting substances (blood)
Characteristics of Connective Tissue
Three characteristics make connectivity tissues different from other primary tissues
- Have messenchyme (an embryonic tissue) as their common tissue of origin
- Have varying degrees of vascularity
- Have extracellular matrix
- -Connective tissue not composed mainly of cells
- -Largely nonliving extracellular matrix separates cells
- —-So can bear weight, withstand tension, endure abuse
Ground Substance
Unstructured material that fills space between cells
-Medium through which solutes diffuse between blood and capillaries and cells
Components
-Interstitial Fluid
-Cell adhesion proteins (“glue”)
-Protein fibers
Connective Tissue Fibers
3 types:
Collagen
Elastic Fibers
Reticular
Collagen
Strongest and most abundant type
Provides high tensile strength
Elastic Fibers
All for stretch and recoil
Like a rubber band) (Elastic band
Reticular
Short, fine, highly branched fibers, internal framework
Branch, forming networks that offer more “give”
Blast Cells
MAKE THE SUBSTANCE: mitotically active, secrete ground substance and fibers
- Fibroblasts in connective tissue proper
- Chrondroblasts in cartilage
- Osteoblasts in bone
- Stem cells in bone marrow
Cyte
Mature form: MAINTAIN matrix
- Chondrocytes in cartilage
- Osteocytes in bone
Fat cells
Store nutrients
White blood cells
Tissue response to injury
Mast cells
Initiate local inflammatory response against foreign microorganisms they detect
Macrophages
Phagocytic cells that “eat” dead cells microorganisms; function in immune system
Classification of Connective Tissue
All connective tissues expect bone, cartilage and blood Two subclasses -Loose Connective Tissues --Areolar --Adipose --Reticular -Dense/Fibrous Connective Tissues --Dense Regular --Dense Irregular --Elastic
Adipose
Similar to areolar but greater nutrient storage
Cell function
-Stores nutrients
Reticular Connective Tissue
Resembles areolar but fibers are reticular fiber
Supports free blood cells in lymph nodes, the spleen, and bone marrow
Dense Regular Connective Tissue
Closely packed bundles of collagen fibers running parallel to direction of pull
-Great resistance to pulling
-Fibers slightly wavy so stretch a little
Poorly vascularized
Make up tendons and ligaments
Dense Irregular Connective Tissue
Same elements but bundles of collagen thicker and irregularly arranged
Resists tension from many directions
-Fibrous joint capsule
Elastic Connective Tissue
Similar but more stretchy than dense regular connective tissue
Some ligaments very elastic
-Those connecting adjacent vertebrae
Cartilage
Chondroblasts and chondrocytes Tough but flexible Lacks nerve fibers Up to 80% water- can rebound after compression Avascular -Retrieves nutrients from membrane surrounding it --Perichondrium Three Types of Cartilage -Hyaline Cartilage -Elastic Cartilage -Fibrocartilage
Bone
Also called osseous tissue Supports and protects body structures Stores fat and synthesizes blood cells in cavities Has inorganic calcium salts Osteoblasts produce matrix Osteocytes maintain the matrix Richly vascularized
Blood
Most atypical connective tissue- is a fluid
Suspension
Red blood cells most common cell type
Also contains white blood cells and platelets
Functions in transport
Muscle Tissue
Highly vascularized Responsible for most types of movement Three Types -Skeletal -Cardiac -Smooth
Skeletal Muscle Tissue
Found in skeletal muscle
Voluntary
Cardiac Muscle Tissue
Found in walls of heart
Involuntary
Smooth Muscle Tissue
Mainly in walls of hollow organs other than heart
Involuntary
Nervous Tissue
Main component of nervous system -Brain, spinal cord, nerves -Regulates and controls body functions Neutrons -Specialized nerve cells that generate and conduct nerve impulses
Mucous Membranes
Mucosae
-line body cavities open to the exterior
(e.g. digestive, respiratory, urogenital tracts)
Moist membranes bathed by secretions (or urine)
May secrete mucus
Serous Membranes
Serosae- found in closed ventral body cavity
Serous fluid between layers
Moist membranes
(E.g Pleurae, pericardium, peritoneum)
Tissue Repair
Necessary when barriers are penetrated Cells must divide and migrate Occurs in two majors ways -Regeneration -Fibrosis
Regenereation
Same kind of tissue replaces destroyed tissue
Original function restored
Same action
Fibrosis
Connective tissue replaces destroyed tissue
Original function lost
Seared- no function
Steps of Tissue Repair
Inflammation
Organization- restores blood supply
Regeneration and Fibrosis
Inflammation
Release of inflammatory chemicals
Dilation of blood vessels
Increase in vessel permeability
Clotting occurs
Organization- restores blood supply
Granulation tissue replaces clot
Epithelium regenerates
Collagen fibers form
Debris is phagocytized
Regeneration and Fibrosis
Scab detaches
Tissue matures
Results in a fully regenerated epithelium with underlying scar tissue
Regenerative Capacity in Different Tissues
Regenerate extremely well
-Epithelial tissues, bone, blood-forming tissue
Virtually no functional regenerative capacity
-Cardiac muscle and nervous tissue of brain and spinal
Developmental Aspects
Primary “derm” layers
- Superficial to deep: ectoderm, mesoderm, and endoderm
- Specialize to form primary tissues
