Connective tissues Flashcards
What are the 4 types of tissue?
Epithelium, connective, nervous, muscle
Function of connective tissue
provide structure and function to organs and other tissues
Connective tissues in the head of femur
articular cartilage, periosteum, cortical/compact bone, spongy/trabecular bone, fatty marrow (adipose)
How does the structure of tendons reflect their function?
Dense, fibres run in parallel. High tensile strength to transfer force of muscle contraction to bone.
Structure of a kidney tubule
Simple cuboidal epithelium resting on a basement membrane (CT composed of collagen fibres)
3 main components of connective tissue
Ground substance, fibres, cells
What do the fibres and ground substance form?
Extracellular matrix
Functions of ground substance
Provides structural and biochemical support, water-binding ability (tissue volume) and supports intercellular exchange of substances via diffusion.
What is ground substance composed of?
Glycoproteins and complex carbohydrates (e.g. hyaluronic acid, glucosamine) - forms clear, semi-solid gel
Function of fibres
Provide tensile strength and structural integrity (supporting framework for ground substance and cells)
2 main types of fibres
collagen and elastin
How does the structure of elastin relate to its function?
Fibres are long and branched which provide stretch and recoil ability.
Which cells synthesise and secrete collagen and elastin into the ECM?
Fibroblasts
Where is type I collagen found?
Fibrous tissues (dermis of skin, tendons, ligaments, bone)
Where is type II collagen found?
Hyaline cartilage
Structure and location of type III collagen?
Delicate branched ‘reticular’ network found in highly cellular organs (liver, lymph nodes)
Which organs is elastin found in?
Blood vessels, skin, bladder, lungs
Function of connective tissue cells
to synthesise, secrete, recycle ECM (ground substance and fibres)
What suffix is given to cells that synthesise and secrete the ECM?
-blasts
What suffix is given to cells that maintain the ECM?
-cytes
What suffix is given to cells that recycle/breakdown the ECM?
-clasts
Function of odontoblasts
Synthesise dentin in teeth
Highly vascularised meaning
Contain lots of blood vessels and lymph vessels therefore immune cells are present.
All connective tissue is highly vascularised except:
cartilage, tendons and ligaments (very few)
Consequence of not being vascularised
Tissue cannot repair itself / very slow
3 classification classes of connective tissues
- connective tissue proper
- skeletal connective tissue (cartilage, bone)
- fluid connective tissue (blood, lymph)
How is connective tissue proper subdivided?
Loose (few fibres, more ground substance) and dense (more fibres, less ground substance)
What is areolar tissue?
Loose arrangement of collagen and/or elastin fibres. Packing material - supports and binds other tissues
Location of areolar tissue
beneath skin, submucosa, surrounding capillaries
structure of adipose tissue
loose connective tissue made of adipocytes found in isolation or in clusters throughout fibrous CT. Adipocytes hold lipid droplet in centre of cell (lipid removed in tissue preparation)
Function of adipose tissue
energy storage, shock absorption, insulation
Location of adipose tissue
deep layers of dermis, breasts, abdomen, hand and foot pads.
Structure of reticular tissue
Loose arrangement of delicately branched (type III) collagen fibres
Function of reticular tissue
Supporting network to highly cellular organs (liver, lymph nodes, spleen - e.g. creates a fine scaffold to support hepatocytes)
3 examples of loose connective tissue proper
Areolar, adipose, reticular tissue
3 examples of dense connective tissue proper
Dense regular, dense irregular, elastic tissue
Structure and function of dense regular tissue?
Dense arrangement of collagen fibres running in same direction. Provides tensile strength.
Where is dense regular tissue found?
tendons and ligaments
Structure and function of dense irregular tissue
Dense arrangement of collagen and elastin fibres in random orientation. Provides strength, stretch and recoil in multiple directions.
Where is dense irregular tissue found?
dermis of skin, protective capsule around organs
Structure and function of elastic tissue
Dense arrangement of elastic and collagen fibres. Allows stretch and recoil of tissues.
Where is elastic tissue found?
arteries, lungs, under transitional epithelium in the bladder
Cause of scurvy
lack of vitamin C
Effects of scurvy
defective collagen formation - loose teeth/periodontitis, skin haemorrhages/poor wound healing, weakness, anaemia
Treatment of scurvy
Vit C supplements, high vit C diet (tomatoes, citrus fruits)
The triple-helical structure of collagen arises from the unusual abundance of which 3 amino acids?
Glycine, proline, hydroxyproline
How does vit C affect collagen synthesis?
Vit C is a co-factor for hydroxylase enzymes which catalyse the addition of OH to proline to form hydroxyproline. In vit C deficient cells, collagen is insufficiently hydroxylated so alpha-helix chains can’t form.
What is Systemic Lupus Erythematosis (SLE)?
Autoimmune disease targeting skin, bones, tendons and kidneys
What are autoantibodies?
Antibodies that incorrectly target host cells (autoimmune)
Head and neck symptoms of lupus
Oral: dryness, soreness, buccal and palatal lesions. Butterfly erythema - redness across cheeks and nose.
What is Sjogren’s?
Autoimmune disease - antibodies target tear and salivary glands.
Symptoms of Sjogren’s
dry eyes and mouth. increased dental caries and candidiasis (less saliva -> fewer antimicrobial proteins -> more fungi/bacteria)
