Connective Tissue Flashcards
Connective tissue (CT) locations
- Fat tissue
- Cartilage
- Tendons
- Ligament
- Bone
- Blood
Functions of Connective Tissues
- Connect epithelium to the rest of the body (basal lamina)
- Provide a route for blood supply, lymph and nerves
- Provide compartments and capsule protection for organs – allow independent
movement of organs and muscle - Provide structure (ligaments, tendons & bone)
- Store energy (fat)
- Transport materials (blood, defense cells)
* CT has no contact with the environment
Connective Tissue Composition
- Specialized cells
- Extracellular protein fibers
- Fluid known as ground substance
(2 & 3 are part of the Matrix)
The Matrix
- extracellular components of connective tissues (fibers and ground substance) make up the matrix
- makes up the majority of tissue volume
- Determines specialized function Matrix
Classification of Connective Tissues
- Connective tissue proper
* Connect and protect (adipose, tendons, ligaments)
* Subdivided into loose and dense CT proper - Fluid connective tissues
* Transport (blood and lymph) - Supportive connective tissues
* Structural strength (bones, cartilage)
Types of Connective Tissue Proper
Fibroblasts
Fibrocytes
Adipocytes (fat cells)
Mesenchymal cells (stem cells)
Macrophages (Scavengers)
Mast cells
Lymphocytes (WBC)
Microphages (WBC)
Melanocytes
Fuctions of Connective Tissue
Fibroblasts, Fibrocytes, Adipocytes (fat cells), Mesenchymal cells (stem cells):
* Maintenance
* Repair
* Energy storage
Macrophages and mast cells:
* Defend and repair damaged cells
Lymphocytes, Microphages, Melanocytes:
* Gives tissues colour
Fibroblasts
- The most abundant cell type:
- found in all connective tissue proper
- secrete proteins and hyaluronan (cellular cement, a polysaccharide derivative)
Fibrocytes
- The second most abundant cell type:
- found in all connective tissue proper
- maintain the fibers of connective tissue proper
Melanocytes
- Synthesis and store brown pigment melanin
- Common in epithelium of skin
- Abundant in connective tissues of the eye and dermis of the skin
Mesenchymal cells (stem cells)
- Respond to local injury or infection
- Divide to produce daughter cells that differentiate into fibrocytes, macrophages, or other connective tissue cells
Adipocytes (fat cells)
- contains a single, large lipid droplet
- Cell content (nucleus, organelles, cytoplasm) are squeezed to side
- Number of adipocytes varies from one type of connective tissue to another, from one region of the body to the another, and among individuals
Mast cells
- Cytoplasm filled with granules containing heparin and histamine
- Histamine – released after injury or infection; stimulates local inflammation
- Heparin – levels in blood normally low; anticoagulant that enhances blood flow
during inflammation; reduces the development of blood clots
Lymphocytes
- Migrate throughout the body
- Tissue damage causes increase in number
- Some develop into plasma cells which produce antibodies
Microphages (neutrophils and eosinophils)
- Phagocytic blood cells
- Attracted to site of an infection or injury
Connective Tissues Fibres
- Collagen
- Reticulin
- Elastin
Collagen fibers
- Most common fibers in connective tissue proper
- Long, straight, and unbranched
- Strong and flexible – rope like
- Resist force in one direction
- For example, in tendons and ligaments
Reticular fibers
- Network of interwoven fibers (stroma)
- Strong and flexible
- Resist force in many directions
- Stabilize functional cells (parenchyma of the spleen) and structures
- For example, in sheaths/capsules around organs
Elastic fibers
- Contain elastin
- Branched and wavy
- Return to original length after stretching
- For example, elastic ligaments of vertebrae
Ground Substances
- Is clear, colorless, and viscous
- Fills spaces between cells, surrounds connective tissue fibres
- Viscous so slows pathogen movement
Loose Connective Tissue
- Fill spaces between organs
- Support epithelia
- Cushion and stabilise specialised cells in organs
- Surround and support blood vessels and nerves
- Store lipids
- Provide route for diffusion
Examples of Loose Connective Tissue
- Areolar tissue
- Adipose tissue
- Reticular tissue
Areolar CT
- Least specialised connective tissue in adults
- Has an open framework – can distort without damage because its fibres are loosely organised
- Contains elastin fibres
- CT just under epithelium of skin
- Allows independent movement of skin and underlying structures (e.g. muscle)
- Capillaries deliver oxygen and nutrients, and remove carbon dioxide and waste products
Areolar CT Locations
Within and deep in the dermis of the skin, and covered by epithelial lining of the digestive, respiratory and urinary tracts; between muscles; around joints; blood vessels and nerves
Adipose CT Location
Deep to the skin, especially the sides, buttocks, and breasts; padding around eyes and kidneys
Adipose CT
- Provides padding, absorbs shocks
- Serves as packing or filler around structures
- Acts as an insulator to slow heat loss through skin
- Role in energy storage
Dense Connective Tissue
- created mostly from fibres
- Tightly packed with high numbers of collagen or elastic fibers
Dense Regular Connective Tissue
- Tightly packed, parallel collagen fibers
- Reduces friction between muscles
- Tendons
-Cords of dense regular connective
tissue- Attach muscles to bones
- Ligaments
- connect bone to bone and stabilize
organs
- connect bone to bone and stabilize
- Aponeuroses
- attach in sheets to large, flat muscles
- Associated with large muscles of the
skull, lower back, and abdomen
- Tendons
Examples of Dense Connective Tissue
- Dense regular connective tissue
- Dense irregular connective tissue
- Elastic tissue
Dense Regular Connective Tissue Locations
Between skeletal muscles and skeleton (tendons and aponeuroses); between bones or stabilizing positions of internal organs (ligaments); ; covering skeletal muscles; deep fasciae
Dense Irregular Connective Tissue
- Interwoven networks of collagen fibers with no consistent pattern
- Gives strength to the deep layer of the skin (the dermis)
- Layered in skin
- Around cartilages (perichondrium)
- Around bones (periosteum)
- Form capsules around some organs (e.g. liver, kidneys)
Elastic Tissue
- Type of dense regular connective tissue; made of elastic fibers
- Help stabilize the positions of the vertebrae of the spinal column
- Cushions shocks
- Permits expansion and contraction of organs
Elastic Tissue Locations
Between vertebrae of the spinal column (ligamenta flava and ligamentum nuchae); ligaments supporting penis; ligaments supporting transitional epithelial; in blood vessel walls
Supportive Connective Tissue
- Provide framework to support body
Skeletal system - Includes:
- Bone
- Cartilage
Cartilage
- Cartilage is a firm but flexible tissue
- Contains only one cell type chondrocytes
* Occupy small chambers known
as lacunae
* Immature chondrocytes are
called chondroblasts – actively
secrete matrix during cartilage
growth - Matrix is a firm gel containing chondroitin sulfates
- Cartilage set apart from surrounding tissues by fibrous perichondrium
o Perichondrium contains two
distinct layers
Outer fibrous region of dense
irregular connective tissues -
gives protection and support, and
attaches cartilage to other
structures
Inner, cellular layer - important
for growth and maintenance of
cartilage
o Blood vessels in perichondrium
provide oxygen and nutrients to
the underlying chondrocytes
Types of Cartilage
o Hyaline cartilage
o Elastic cartilage
o Fibrocartilage
Examples of Hyaline Cartilage
o Connections between the ribs and the sternum
o Nasal cartilages
o Articular cartilages covering opposing bone surfaces within many joints – such as elbow and knee
Hyaline Cartilage
- Most common type of cartilage
- Dense perichondrium surrounds hyaline cartilages (except inside joint
cavities) - Tough but flexible – matrix contains closely packed collagen fibres
Hyaline Cartilage Functions
Provides stiff but somewhat flexible support; reduces friction between bony surfaces
Hyaline Cartilage Locations
Between tips of ribs and bones of sternum; covering bone surfaces at synovial larynx (voice box), trachea, and bronchi; forming part of nasal septum
Elastic Cartilage
- Extremely resilient and flexible – contains numerous elastic fibres
Examples of Elastic Cartilages
oExternal flap (the auricle) of the outer ear
oEpiglottis – prevents food and liquids entering the windpipe when swallowing
oAuditory canal – passageway to the middle ear cavity
oSmall cartilages in the larynx, or voice box
Elastic Cartilages Function
Provides support, but tolerates distortion without damage and returns to original shape
Fibrocartilage
- Extremely durable and tough – it has little ground substance and the matrix has densely interwoven collagen fibres
- Resists compression
- Absorbs shocks
- Prevents damaging bone-to-bone contact
- Limits movement
Examples of Fibrocartilages
o Intervertebral discs (pads of fibrocartilage) between the spinal vertebrae
o Around tendons
o Within and around joints
o Between pubic bones of the pelvis
Bone tissue
- Very small volume of ground substance in bone
- Approximately 2/3 of the matrix of bone is calcified
oConsists of mixture of calcium salts – calcium phosphate, calcium
carbonate
oRest is dominated by collagen fibres
oOsteocytes – bone cells (generally organised in groups around the central canal that contains blood vessels)
oSurfaces generally sheathed by a periosteum composed of fibrous outer
layers and cellular inner layers
Bone tissue functions
Supports and protects (by enclosing); provides levers for the muscles to act on; stores calcium and other minerals and fat; marrow inside bones is the site for blood cell formation (hematopoiesis)
Subclasses of Bones Tissue
- Compact bone- relatively dense and solid. Forms a sturdy protective layer that surrounds medullary cavity (central space), or marrow cavity
- Spongy bone (trabecular bone)- open network of struts and plates
Fluid Connective Tissue
- Blood: Fluid in blood vessels
Consists of blood cells surrounded
by plasma (matrix)
Functions as transport vehicle for
CVS - Lymph: Fluid that is collected from the
capillary beds and flows through
the lymph glands and lymph
organs
Lymph has some white blood cells
Blood Tissue
- Watery matrix called plasma
- Contains blood cells and fragments of cells»_space; known as formed elements
- Formed elements include:
Red blood cells, white blood cells, platelets
Red Blood Cells
(erythrocytes) transport oxygen (and to a lesser degree carbon dioxide) in the blood.
Lack a nucleus. They account for about half of the volume of whole blood and give its colour.
White Blood Cells
(leukocytes) are nucleated cells, which defend the body from infection and disease.
Platelets
membrane - enclosed packets of cytoplasm that function in blood clotting.
These cells fragments are involved in clotting response that seals leaks in damaged or broken blood vessels.
Lymph Tissue
- Forms as interstitial fluid enters lymphatic vessels
- Fluid passes along lymphatic vessels where lymphocytes respond to injury or infection
- Lymphatic vessels return lymph to large veins near heart
- Recirculation of fluid from CVS, through interstitial fluid, to the lymph, and back to the CVS
- continuous process, helping eliminate wastes, maintain blood volume, and alert
immune system to infections in peripheral tissues
Types of Membranes
- Mucous (lines tubes in the body, e.g., gut)
- Serous (lines body cavities and secretes fluid, e.g. pleural cavity membranes)
- Cutaneous (Skin)
- Synovial (Outer area of a joint)
Mucous membranes (mucosae)
- Line passageways that have external connections
- In digestive, respiratory, urinary, and reproductive tracts
Mucous Membranes Structure
Epithelial cells – usually simple:
* Surfaces must be moist to reduce friction
* Moisture by:
* Mucus produced by goblet cells,
* by gland secretions
* by fluids (eg urine or semen)
* Moisture facilitates absorption and excretion
Lamina propria:
* Is the areolar loose connective tissue
Serous membranes
- Line cavities not open to the outside
- Are thin but strong
- Have fluid transudate to reduce friction
Types of Serous Membranes
- Peritoneum
- Pleura
- Pericardium
Mesothelium
special name for the epithelium lining body cavities
Cutaneous membrane
- Is skin, surface of the body
- Thick, relatively waterproof, and dry
- Epithelium in epidermis and CT in the Dermis
- CT connects epith to underlying structures
- Loose Aerolar first and then Dense irregular CT proper
Synovial membranes
- Line the moving, articulating joint cavities
- Produce synovial fluid (lubricant)
- Protect the ends of bones
- Lack a true epithelium
Internal Framework of the Body
Connective tissues:
* Provide strength and stability
* Maintain positions of internal organs
* Provide routes for blood vessels, lymphatic vessels, and nerves
Fasciae:
* Singular form is fascia
* The body’s framework of connective tissue
* Layers and wrappings that support or surround organs
Types of Fasciae
- Superficial fascia
- Deep fascia
- Subserous fascia
Superficial Fascia
- Between skin and underlying organs
- Areolar Tissue and adipoise tissue
- Also known as subcutaneous layer or hypodermis
Deep Fascia
- Forms strong, fibrous internal framework
- Dense connective tissue
- Bound capsules, tendons and ligaments
Subserous Fascia
- Between subserous membranes and deep fascia
- Areolar tissue
