Connective tissue Flashcards
What are the two basic elements of connective tissue ?
Extracellular matrix and cells
Is the connective tissue composed of cells closely packed?
No, unlike epithelial tissue there is a large amount of extracellular material in connective tissue.
What does the extracellular matrix consist of ?
Ground substance and fibres.
What are the three common characteristics of connective tissue?
- Cells
- Large amount of ground structure lacking shape (amorphous)
- Protein fibres
What produces the extracellular fibres ?
Connective tissue cells
What determines most of the function of the tissue?
The extracellular matrix
Is connective tissue highly vascularized ?
Yes, but there are exceptions such as cartilage which is avascular.
Tendons and ligaments have a small blood supply.
Are all connective tissue supplied with nerves ?
No, all are supplied with nerves except cartilage.
Functions of connective tissue
- Connect and support other tissue
- Protect
- Transport fluid, nutrients, waste and chemical messengers - Store energy
- Thermal insulation
From which embryonic layer does connective tissue derive from ?
Mesodermal layer
What is the first connective tissue to develop in the embryo ?
Mesenchyme - the stem cell line which all connective tissue later develops from
What embryonic connective tissue develops from the umbilical cord ?
Mucous connective tissue or Whartons jelly. It is no longer present after birth.
“blast” - suffix meaning
Immature class of cells. They retain the capacity for cell division and secrete the extracellular matrix.
“cyte” - suffix meaning
Mature cell. Mostly involved in monitoring and maintaining the extracellular matrix.
What are three types of fibers found in the extracellular matrix?
- Collagen fibers
- Elastic fibers
- Reticular fibers
What are the function of the fibers in the extracellular matrix ?
They strengthen and support the connective tissue.
Describe collagen fiber
Very strong and resist pulling forces (tension). Not stiff, allow flexibility. Collagen fibers often occur in parallel bundle. The bundle arrangements provide tensile strength. Consist of protein collogen.
Where are collagen fibers mostly found ?
Bone, cartilage, tendons (muscle to bone) and ligaments (bone to bone).
Describe elastic fibers.
Smaller in diameter than collagen fibers. Brain and join together to form a fibrous network within a connective tissue. Consists of the protein elastin, surrounded by glycoprotein, fibrillin - adds strength and stability. Strong but can be stretched. Have the ability to return to their original shape.
Where are elastic fibers mostly found ?
Skin, blood vessel walls and lung tissue.
Describe reticular fibers
Consist of collogen, arranged in fine bundle with a coating of glycoprotein. Produce by fibroblasts. Much thinner than collogen and form a branch network. Provide strength and support. These fibers also help form the basement membrane.
Where can reticular fibers be found ?
Soft organs - spleen and lymph nodes. Also, blood vessels.
What are the three overarching classification of connective tissue ?
- Connective tissue proper
- Supportive connective issue
- Fluid connective tissue
What are the subcategories of connective tissue proper ?
- Loose connective tissue
- Dene connective tissue
What are the types of loose connective tissue?
- Areolar
- Adipose
- Reticular
What are the types of dense connective tissue ?
- Dense regular
- Dense irregular
- Elastic
What are the subcategories of supportive connective tissue ?
Cartilage:
- Hyaline
- Fibrocartilage
- Elastic
Bone
What are the types of fluid connective tissue ?
- Blood
- Lymph
Which cell is present in all connective tissue proper ?
Fibroblasts
Which cells are fixed cells in connective tissue ?
Fibrocytes, adipocytes and mesenchymal cells.
What do fibroblasts do ?
Secrete polysaccharides and proteins, which combine with extracellular fluids to produce a viscous grand substance which contain fibrous proteins.
What is the mature version of fibroblasts ?
Fibrocyte
What are adipocytes ?
Cells that store lipids as droplets that fill most of the cytoplasm.
What types of adipocytes are there?
White and brown
What is white adipocytes ?
Store lipids as a single drop and metabolically less active.
Effectiveness seen at obese individuals.
What is brown adipocytes ?
Store lipids as many droplets and have a high metabolic activity.
What does loose connective tissue do ?
Absorb shock and bind tissues together. Allows water, salts and various nutrients to diffuse through to adjacent or imbedded cells and tissues.
What is adipose tissue ?
Type of loose connective tissue.
- Mostly fat storage cells, little extracellular matrix
- Has a large number of capillaries allowing rapid storage and mobilization of lipid molecules
- Most abundant adipose
- Serves as insulation from cold temperature and mechanical injuries
What can white adipose tissue be found protecting ?
Kidneys and cushioning the back of the eye
What is brown adipose tissue ?
Type of connective tissue
- More common infants
- In adults there is a reduced amount of brown fat
- the numerous mitochondria explain the its efficiency in metabolizing fat
- thermogenic
Which adipose has numerous mitochondria to enable high metabolic activity ?
Brown adipose
Does an obese person have more blood vessels?
Yes, in their adipose tissue - potentially causing high blood pressure.
Aerolar tissue
Type of loose connective tissue
- shows little specialization
- Cell types and fibers are distributed in a random, web like fiber
- Fills space between muscle fibers, surrounds blood and lymph vessels, supports organs in the abdominal cavity
- Underlines most epithelial tissue
- represents the connective tissue component of the epithelial membrane
Function of areolar connective tissue ?
Strength, elasticity and support
What is reticular tissue ?
Type of loose connective tissue
- mesh like, supportive framework
- Soft organs such as lymphatic tissue, the spleen and the liver.
- Produce reticular fibers that form a network onto which other cells can attach
What differs dense connective tissue to loose connective tissue ?
Dense connective tissue has more collagen. Hence, it has a greater resistance to stretching. It has more fibers and there more densely packed but less cells.
What dense regular connective tissue ?
The fibers are parallel to each other. It has greater tensile strength and resistance to stretching in the direction of the fiber orientation.
Physical description of dense regular connective tissue ?
Shiny white extracellular matrix.
Collagen fibers regularly arranged in bundles with fibroblasts in row between them.
Why do tendons and ligaments heal slowly ?
Collogen fibers are non living so they heal slowly.
What are tendons
Type of dense regular connective tissue. Attach muscle to bone.
What are ligaments?
Attach bone to bone.
What are examples of dense regular connective tissue ?
Ligaments and tendons
* in ligaments fibers parallel
What is dense regular elastic tissue ?
It contains elastic fibers in addition to the collogen fibers. The elastic fibers allow it to return to original shape after stretching. Regular as fibers are parallel to each other.
What are examples of dense regular elastic connective tissue ?
The ligaments in the vocal folds and between the vertebral column.
What is dense irregular connective tissue ?
The direction of the fibers are random.
Gives the tissue strength in all directions and less strength in one direction.
- can form mesh = crisscross
- alternating layers
Example of dense irregular tissue ?
Dermis of the skin.
What gives arterial walls the strength and ability to regain original shape after stretching ? (what tissue type)
Dense irregular elastic connective tissue
What are cartilage ?
Dense network of collagen fibers and elastic fibers in chondroitin sulphate. Can endure more stress than dense and loose connective tissue.
What results in the strength of cartilage ?
Collagen fibers
What results in the resilience of cartilage ?
Chondroitin sulphate
How does cartilage differ from other connective tissue ?
It does not have nerves or blood vessels in it extracellular matrix.
What are the cells of mature cartilage ?
Chondrocytes. They occur singly or in groups within spaces called lacunae.
Why does cartilage heal poorly after injury ?
It does not have blood supply.
What encapsulates cartilage ?
Perichondrium - dense irregular connective tissue. it contains nerve and blood vessels. It is a source of new cartilage cells.
What type of connective tissue is a precursor for bone?
Cartilage
What are the three main types of cartilage tissue ?
- Hyaline
- Fibrocartilage
- Elastic
What is hyaline cartilage ?
Most common type of cartilage in the body
- Consists of short and dispersed collagen fibers
- Contains a large amount of proteoglycans
- Strong and flexible
Appearance of hyaline cartilage
Smooth
Where is hyaline cartilage found ?
- Rib cage
- Nose
- Covers nose where they meet to form joins
- plate of hyaline cartilage at ends of the bone allow continued growth to adulthood.
- forms template of embryonic skeleton
What is fibrocartilage ?
- Tough
- Thick bundles of collagen dispersed through matrix
- Don’t have a perichondrium
Examples of fibrocartilage ?
Menisci in the knee joint and in the intervertebral discs.
Elastic cartilage
Contains elastic fibers alongside collagen and proteoglycans.
- Gives rigid support as well as elasticity.
What contains cartilage ?
Ear lobe
Bone
- Hardest connective tissue
-Protection of internal organs and supports the body - rigid extracellular matrix contains mostly collagen fibers embedded in a mineralizes ground substance containing hydroxyapatite
- organic and inorganic contribute to unusual properties of the bone
- Highly vascularized
What is hydroxyapatite ?
A form of calcium phosphate
What would occur to bones without collagen ?
They would be brittle and shatter easily.
What would happen to bones without mineral crystal ?
Bones would flex and provide little support.
What is located in the lacunae of bones cells ?
Osteocytes
Can bone tissue recover from injuries in a short time or long time ?
Short time, they are highly vascualrised.
Fluid connective tissues
Blood and lymph..
