L12- Connective And Adipose Tissue Flashcards
What are the 6 types of connective tissue? (Alpha order)
Adipose Bone Blood Cartilage Dense CT Loose CT
What are the 3 main groups of connective tissue and their functions?
- Loose Connective tissue: holds organs in place and attaches epithelial tissue to underlying tissue
- Dense Connective tissue: helps attach muscle to bone and links bones together at joints
- Specialised connective tissue; Number of diff tissue and unique ground substances —> adipose, cartilage, bone, blood lymph
What is the structure of connective tissue?
- Cells- mainly mature fibroblasts, fixed adipocytes and reticular cells
- Fibres: Collagen, elastin and reticulin fibres
- Ground substance: proteoglycans (glucosaminoglycans e.g. hyaluronic acid)
What makes up the extracellular matrix?
Ground substance and fibres
Functions of connective tissue?
- Binding and supporting e.g. holding skin, gut lungs together
- Protecting e.g. bones protect organs
- Insulating e.g. fat
- Storing reserve fuel and cells (bone marrow and fat tissue)
- Transporting substances within body (Blood and interstitium)
- Separation of tissues (fascia and tendons/cartilage)
Cell types found in connective tissue?
- undifferentiated mesenchymal cells
- fibroblasts
- storage cells
- adipocytes
- macrophages
- mast cells
What are fibroblasts and their functions?
- most common cells in ct
- synthesise and secrete collagen and other fibres that lie within ground substance (EC matrix)
- scars are formed by fibroblast activity during tissue repair (collagen)
What is a myofibroblast?
Modified fibroblasts
- contain actin and myosin
- responsible for wound contraction when tissue loss has occurred
Function of macrophages in CT?
- derived from blood monocytes, move into loose connective tissue especially during inflammation
- phagocytic and can degrade foreign organism and cell debris
- also antigen presenting cells
- contain numerous lysosomes which break down ingested material
Function of mast cells in CT?
- release chemical signals that diffuse through ground substance and trigger inflammation
- Cytoplasm of mast cells packaged with secretory vesicles which contain: histamine (increase blood wall permeability), heparin (anticoagulant) and cytokines (attract eosinophils and neutrophils)
- coated with Ige molecules which bind allergens
a) What are the two types of adipocytes?
B) compare them
A) White adipocytes and brown adipocytes
B) White: - Yellow - Unilocular (single enormous lipid droplet) - peripheral nucleus - normal amt of mitochondria - lots in adults, none in neonates - function: padding, shock absorber, insulin and energy reserve
Brown:
- Brown
- multilocular: multiple small lipid droplets
- central nucleus
- lots of mitochondria (colour)
- only adipocytes in neonates, some in adults
- function: insulation and energy reserve.
What are the types of fibres in CT?
- Collagen
- Elastin
- Reticulin
A) What are the types of collagen?
A) there are 4 types:
- type 1: found in tendons, organs and skin dermis (forms fibres)
- type 2: doesn’t form fibres- found in hyaline and elastic cartilage
- type 3: forms fibres around muscle and nerve cells and within lymphatic tissue and lymphatic organs CALLED RETICULIN
- type 4: form basement membrane
Function of:
A) collagen
B) reticulin
C) elastin
A) flexible with high tensile strength
B) provides a supporting framework/sponge
C) allows tissues to recoil after stretch or dissension
a) Which fibre is not present in areolar tissue?
B)Where is this fibre found?
A) Reticulin
B) lymphatic tissue
A) What is the ground substance?
B) what is its composition?
A) the background material within which all other connective tissue elements are embedded. Clear viscous substance with a slippery feel
B)
- High water content: provides transport route by diffusion between tissues
- water is stabilised by a complex of glycosaminoglycans (GAGS), proteoglycans and glycoproteins
A) what are proteoglycans?
B) what are glycosaminoglycans? (GAGS)
A) large macromolecules consisting of a core protein to which GAG is covalently bound
B) long chained polysaccharides, attract water to form a hydrated gel which permits rapid diffusion but also resits compression
Example of a GAG found in the ground substance of cartilage?
Hyaluronic acid
What is loose connective tissue also known as?
Areolar tissue
Loose connective tissue:
A) Proportion of ground substance, cells and fibres
B) cell types?
C) fibres?
D) where is it found?
E) what is special about the places it can be found and how does it relate to its function?
F) examples
A) Lots of ground substance and cells, less fibres
B) multiple cell types: fibroblasts, macrophages, mast cells and adipocytes
C) only collagen and elastin
D) Under epithelial layers (e.g. lamina propria), around glands, surrounds capillaries, nerves and sinusoids
E) found in sites where pathogens can breach an epithelial surface and can be challenged and destroyed by cells of immune system —> ct can undergo swelling as it can expand and return to origina size
F) superficial layer of dermis in skin and submucosa of colon
Dense connective tissue:
A) Proportion of ground substance, cells and fibres
B) cell types?
C) fibres?
D) where is it found?
E) what is special about the places it can be found and how does it relate to its function?
A) lots of fibres and relatively smaller proportions of ground substances and cells
B) less cell types
C) all fibre types
D) principal components of tendons, ligaments, aponeuroses (flattened tendons) and fascia, also dermis of skin
E) provide mechanical support for various structure and transmit forces used in muscular movements
A) What is the two types of dense connective tissue?
B) And what is their differences?
C) examples of both
A)
- Dense IRREGULAR connective tissue: fibres running in different directions
- Dense REGULAR connective tissue: fibres running in parallel to each other
B)
Irregular:
-fibres that run in all directions
- Resists stresses/forces in all directions- very strong
- mostly collagenous but also reticulin and elastin
Regular:
- collagen fibres are densely packed and run in parallel to each other
- found in areas where large amounts of tensile strength required
- resists stress/forces in only one direction
C)
Irregular; reticular layer of dermis of skin, glandular tissue, walls of organs and in whites of eye
Regular: Found in tendons, ligaments and aponeuroses
What are the following and how does their structure relate to their function?
A) Tendons
B) ligaments
A)
- connect muscles to bones
- very strong
- Skeletal muscle fibres connect with tendon collagen at mayo tending us junctions provides strength —> tensile force exerted by muscle
B)
- connects bone to bone
What is fascia?
- band or sheet of connective tissue found under the skin
- made up of fibrous connective tissue containing collagen fibres in a direction paralel of pull
- flexible and can resist tension
A) what can vitamin c deficiency lead to?
B) How?
C) Symptoms
A) scurvy
B)
- Vit c is required for intracellular production of pro collagen which is then converted to collagen outside the cell
- collagen forms fibres that provide strength to tissue e.g. bones, tendons, ligaments and fascia
- without it, collagen formation is distrusted leading to poor wound healing and impaired bone function
C) Gum disease, bruising of skin, bleeding, poor wound healing
Why is vitamin c important in the diet?
It is not stored in the body as it is water soluble and needs to be replaced every day in the diet.
If a patient presented with the following symptoms what would you suspect they had?
- abnormally tall, arachnodactyly (long fingers), joint dislocation, arm span greater than height
Marfans syndrome
A) What is the function of fibrillin 1 gene?
B) What is the clinical relevance of a mutation of this gene?
A) To produce fibrillin, this surrounds elastic fibre to give it its normal function of recoil
B) mutation will lead to abnormal elastin tissue
How are patients with marfans at risk of an aortic aneurysm?
- elastic tissue is abnormal
- elastin needed to recoil in aorta
- overtime the elastin will be weaker and the aorta less able to recoil and hence will dilate/form a bulge (an aneurysm)
- this is life threatening as it can burst/rupture and lead to internal bleeding
What is osteogenesis imperfecta?
- mutated collagen fibres that do not knit together or there is not enough collagen produced
- symptoms: weakened bones, fractures, short stature, blue sclera, hearing loss, hyper mobility and flat or arched feet and poor teeth development.
COMPARE loose and dense connective tissue?
Loose:
- known as areolar
- lots of cell types
- no reticulin
- lots of ground substance and cells, less fibres
- holds organs in place and attaches epithelial to underlying tissue
Dense:
- known as fibrous/collagenous
- two types: irregular and regular
- lots of fibres and less ground substances and cells
- helps attach muscle to bones and links bones together at joints
