The tissue level of organization- Connective tissue Flashcards
What are the components of connective tissue
- Specialized cells
- Extracellular protein fibers
- Fluid called ground substance
What are the functions of connective tissues?
– Establishing a structural framework for the body
– Transporting fluids and dissolved materials
– Protecting delicate organs
– Supporting, surrounding, and interconnecting other types of tissue
– Storing energy reserves, especially triglycerides
– Defending the body from invading microorganisms
State the categories of connective tissues
- Connective tissue proper
* Connect and protect - Fluid connective tissues
* Transport - Supporting connective tissues
* Structural strength
State the categories of connective tissue proper
– Loose connective tissue
* More ground substance, fewer fibers
* Example: fat (adipose tissue)
– Dense connective tissue
* More fibers, less ground substance
* Example: tendons
What are the cells of connective tissue proper
– Fibroblasts
– Fibrocytes
– Adipocytes
– Mesenchymal cells
– Melanocytes
– Macrophages
– Mast cells
– Lymphocytes
– Microphages
Describe Fibroblasts
– The most abundant cell type
– Found in all types of connective tissue proper
– Secrete proteins and hyaluronan (cellular ceme
Describe Fibrocytes
– Second most abundant cell type
– Maintain connective tissue fibers
Describe Adipocytes
– Fat cells
– Each cell stores a single, large fat droplet
Describe Mesenchymal cells
– Stem cells that respond to injury or infection
– Differentiate into fibroblasts, macrophages, etc.
Describe Melanocytes
– Synthesize and store the brown pigment melanin
Describe Macrophages
– Large phagocytic cells of the immune system
– Engulf pathogens and damaged cells
– Fixed macrophages stay in tissue
– Free macrophages migrate
Describe Mast Cells
– Stimulate inflammation after injury or infection
* Release histamine and heparin
– Basophils are leukocytes that also contain histamine and heparin
Describe lymphocytes
– Migrate throughout the body
– May develop into plasma cells, which produce
antibodies
Describe Microphages
– Phagocytic blood cells (neutrophils, eosinophils)
– Attracted to signals from macrophages and mast cells
State the three types of connective tissue fibers
- Collagen fibers
- Reticular fibers
- Elastic fibers
Describe Reticular fiber
– Form a network of interwoven fibers (stroma)
– Strong and flexible
– Resist forces in many directions
– Stabilize functional cells (parenchyma) and structures
– Example: sheaths around organs
Describe Elastin Fibers
– Contain elastin
– Branched and wavy
– Return to original length after stretching
– Example: elastic ligaments of vertebrae
What is Ground substance
– Is clear, colorless, and viscous
– Fills spaces between cells and slows pathogen
movement
Describe Loose connective tissues
– “Packing materials”
– Fill spaces between organs, cushion cells, and support
epithelia
Describe embryonic connective tissues
– Not found in adults
– Mesenchyme (embryonic connective tissue)
* First connective tissue in embryos
– Mucous connective tissue
* Loose embryonic connective tissue
What are the types of loose connective tissues in adults
- Areolar tissue
- Adipose tissue
- Reticular tissue
Describe the Areolar Tissue
– Least specialized
– Open framework
– Viscous ground substance
– Elastic fibers
– Holds capillary beds
* Example: under skin (subcutaneous layer)
Describe Adipose Tissue
– Contains many adipocytes (fat cells)
* Adipocytes in adults do not divide
– Expand to store fat
– Shrink as fats are released
* Mesenchymal cells divide and differentiate
– To produce more fat cells
– When more storage is needed
– May be removed (temporarily) via liposuction in cosmetic surgery
What is white fat?
– Most common
– Stores fat and absorbs shocks
– Slows heat loss (insulation)
What is Brown Fat
– Found in babies and young children
– More vascularized
– Adipocytes have many mitochondria
– Breakdown of lipids releases energy and warms body
Describe the reticular tissue
Provides support
– Reticular fibers form a complex, three-dimensional
stroma
– Support functional cells of organs
– Found in liver, kidney, spleen, lymph nodes, and bone
marrow
What is another name for dense connective tissue
Collagenous tissues
What are the three types of dense connective tissue
Dense regular
* Dense irregular
* Elastic
Describe Dense regular connective tissue
– Tightly packed, parallel collagen fibers
* Tendons attach muscles to bones
* Ligaments connect one bone to another and
stabilize organs
* Aponeuroses are tendinous sheets that attach a broad, flat muscle to another structure
Describe Dense irregular connective tissue
– Interwoven network of collagen fibers
* Provides strength to dermis
* Forms sheath around cartilages (perichondrium)
and bones (periosteum)
* Forms capsules around some organs (e.g., liver,
kidneys, and spleen)
What are three layers of fasciae
- Superficial fascia
* Separates skin from underlying tissues - Deep fascia
* Sheets of dense regular connective tissue - Subserous fascia
* Lies between deep fascia and serous membranes that line body cavities
Fluid connective tissue include:
blood and lymph
Describe the blood
Contains a watery matrix called plasma
– Contains cells and cell fragments, collectively known
as formed elements
* Red blood cells (erythrocytes)
* White blood cells (leukocytes)
* Platelets
Describe lymph
– Forms as interstitial fluid that enters lymphatic vessels
– Monitored by immune system
– Returned to veins near the heart
Supporting connective tissue include
cartilage and bone
What are the types of cartilage and describe
▪ Hyaline cartilage
– Most common type
– Tough and somewhat flexible
– Reduces friction between bones
– Found in synovial joints, rib tips, sternum, and trachea
▪ Elastic cartilage
– Supportive but bends easily
– Found in external ear and epiglottis
Fibrocartilage
– Very durable and tough
– Limits movement
– Prevents bone-to-bone contact
– Found around joints, between pubic bones, and between spinal vertebrae
The types of cartilage growth are
– Interstitial growth
* Enlarges cartilage from within
– Appositional growth
* Growth at outer surface of cartilage
Describe the bone
For weight support
– Calcified (made rigid by calcium salts)
– Resists shattering (flexible collagen fibers)
– Osteocytes (bone cells) lie in lacunae
* Arranged around central canals within matrix
* Small channels through matrix (canaliculi) allow for exchange of materials with blood
– Periosteum covers bone
* Fibrous (outer) and cellular (inner) layers
What is the function of tissue membrane
– Physical barriers
– Line or cover body surfaces
– Consist of an epithelium supported by connective tissue
What are the four types of tissue membranes
- Mucous membranes
- Serous membranes
- Cutaneous membrane
- Synovial membranes
Describe the mucous membranes?
– Line passageways that have external connections
– In digestive, respiratory, urinary, and reproductive tracts
– Epithelial surfaces must be moist
* To reduce friction
* To facilitate absorption or secretion
– Lamina propria is areolar tissue in mucous
membranes
Describe the Serous membranes
– Line cavities that do not open to the outside
– Thin but strong
– Parietal portion lines inner surface of cavity
– Visceral portion (serosa) covers the organs
– Serous fluid reduces friction
What are the different types of serous membranes and describe
- Peritoneum
* Lines peritoneal cavity
* Covers abdominal organs - Pleura
* Lines pleural cavities
* Covers lungs - Pericardium
* Lines pericardial cavity
* Covers heart
Describe the cutaneous membrane
– Skin that covers the body
– Thick, relatively waterproof, and usually dry
Describe the synovial membranes
– Line synovial joint cavities
– Movement stimulates production of synovial fluid for
lubrication
– Lack a true epithelium
