Lecture 10 - Connective Tissue Flashcards
Name some of the cells of connective tissue
Fibroblasts, Chondrocytes, Osteocytes, Osteoblasts, Osteoclasts, Adipocytes, Stem cells, Bone marrow etc.
What are the products of CT cells?
Fibres, ground substance, wax and gel like substances
What 3 things are CTs made or structurally?
Cells, fibres and ground substance
Describe some of the functions of CT.
Binding and support - Skin, lungs etc.
Protecting - Bone, fat
Insulation - Fat
Storage - Bone marrow storing cells, fat storing energy
Transport - Blood and interstitium
Tissue Separation - Fascia/tendons
What are the two types of connective tissue and their subdivisions
Loose CT - Areolar tissue “little space”
Eg. Lamina Propria, basal lamina
Dense CT - Fibrous/collagenous tissue:
Irregular - fibres run in all directions
Regular - Fibres run parallel to one another
Loose CT - Name the type of cells and the fibres present in loose CT
Also name the functions
Fibroblasts, macrophages, mast cells
Collagen and elastic
They hold fluid vessels, acts as packaging around organs, holds everything in place generally
Function of fibroblasts
Fibroblasts produce fibres which are present in extracellular matrix aka ground substance
Can mature into myofibroblasts that contain actin for wound contraction
Function of macrophages
Present during local inflammation especially, they phagocyte debris and foreign material
Antigen presenting cells too for T cells
Mast Cells
Contain abundant granules of histamine, heparin and other substances
Present near blood vessels but not in CNS
Coated with IgE which bind to allergens, which then release these granules in the cells
White Fat Cells vs Brown Fat Cells
Unilocular vs Multilocular
Normal levels of mitochondria vs Brown cells having LARGE no of mitochondria
Contributes to brown cells being better energy store and insulator
White adipose lipid breakdown is slow so not used to generate heat (shiver instead)
Brown cells used to generate heat via oxidative phosphorylation and lipid breakdown
Describe the 4 types of collagen
Collagen I - 90% of all collagen, fibrils becomes fibres and fibre bundles, tendons, skin dermis, organ capsules etc.
Collagen II - Fibrils dont form fibres (hyaline and elastin cartilage)
Collagen III - Reticulin (muscle and nerve cells)
Collagen IV - Unique, present in basal lamina
Pathogens that enter via epithelia can be treated by cells in the CT of the basal lamina, gland CT and around blood vessels. Causes CT to swell and then return to normal size
.
2 examples of where loose CT is
Submucosa of the colon
Superficial layer of dermis
What is ground substance?
Viscous, clear substance composed of proteoglycans binded to glycosaminoglycans
Forms a hydrated gel that allows rapid diffusion and resists compression
Example of GAG is hyaluronic acid, binds to PG via a link protein to form hydrophilic macromolecules
Present in cartilage
Differentiate Irregular from Regular dense CT
Both contain fibroblasts
I : Collagen I fibres in all directions resists stress in all directions
Eg. deep dermis, submucosa of intestine
R : Parallel, one direction of stress resistance
Eg. Tendons, ligaments
Look at histology of regular and irregular from lecture and describe them
.
What causes the mechanical strength of the myotendinous joint?
Muscle fibres connect with tendon collagen bundles
Collagen passes from tendon to muscle and interacts w collagen fibres coating muscle
Tendon anatomy
70% Collagen I
30% Collagen III (reticulum)
30% collagen
2% elastin
68% water
What type of CT is in ligaments?
Regular dense CT
Parallel collagen fibres
Fibres undulate
Wrapped in loose CT to make fascicles
Between fascicles are ground substance
What is fascia?
Connective tissue consisting of 3 types: Superficial, deep or visceral/parietal
Made of fibrous CT, bundles of collagen parallel to one another
Resist unidirectional tension forces
Why do we need Vitamin C?
Vitamin C hydroxylates proline and lysine
This leads to form procollagen, which is secreted out of cell and forms collagen outside the cell
Without Vitamin C, cannot form collagen, leading to diseases such as scurvy
What is scurvy?
Lack of vitamin C
Leads to thin collagen aggregating to create thick areas and thinner areas of collagen
Leads to gum disease, bruising, bleeding, poor wound healing
Marfan’s syndrome
Autosomal doninant disorder
Expression of Fibrillin I affected, abnormal elastic tissue
Leads to arachnodactyly, abnormally tall, frequent joint dislocation, catastrophic aortic rupture
Describe structure of elastin fibres
Elastin enfolds and surrounded by fibrillin microfibrils
Occurs in most CT
Important in lungs, artery walls, dermis etc.
Eg. tunica Intima, Tunica Media, Tunica externa
ELASTIN CANNOT BE REPLACED IN ADULTHOOD (smoking)
Osteogenesis Imperfecta
“Brittle bone disease”
Due to mutated collagen fibres that do not knit together or not produced enough
Results in:
Weakened bones Short stature Blue sclera Hearing loss Hypermobility Poor teeth
