Connective Tissue Flashcards
What are the general features of connective tissue (CT)?
Composed of cells and extracellular matrix (ECM). Highly vascular (except cartilage and tendons). Supplied by nerves (except cartilage). Found deep in the body, not on surfaces.
What are the main functions of connective tissue?
Support, protection, binding organs, energy storage (adipose tissue), transport (blood).
What are the two main components of ECM?
Ground substance (GS) and fibres.
What determines the properties of CT?
The composition of the ECM.
How does ECM composition affect tissue properties?
Bone ECM is hard & rigid, while cartilage ECM is firm & rubbery.
What is ground substance composed of?
Water, polysaccharides (GAGs), and proteins.
What are glycosaminoglycans (GAGs)?
Unbranched polysaccharides with repeating disaccharide units.
Why are GAGs hydrophilic?
They have negative charges, which attract positively charged ions and water.
What are proteoglycans?
GAGs covalently bound to a core protein (mostly sugar).
What are glycoproteins?
Proteins with sugar groups attached (more protein than sugar).
What is the function of proteoglycans?
Maintain hydration and gel-like consistency in ECM.
What are the types of sulphated GAGs and their locations?
Keratan sulphate (cartilage, cornea, bone), Chondroitin sulphate (cartilage, bone, skin, blood vessels), Dermatan sulphate (skin, tendons, heart valves, blood vessels), Heparin sulphate.
What is the only non-sulphated GAG?
Hyaluronic acid.
How is hyaluronic acid different from sulphated GAGs?
It does not bind to a core protein.
What is the function of hyaluronic acid?
Viscous, slippery, binds cells together, maintains eyeball shape, lubricates joints.
What is hyaluronidase?
An enzyme that breaks down hyaluronic acid.
What is Exophthalmos?
Abnormal ECM deposition in the eyes due to autoimmune activation of fibroblasts.
What causes Exophthalmos?
Increased GAG deposition in the eye leads to water retention and swelling.
What are the three types of connective tissue fibres?
Collagen fibres, Reticular fibres, Elastic fibres.
What are collagen fibres?
Thick, strong, flexible fibres that resist pulling forces. Most abundant protein (25% of body proteins). Found in cartilage, tendons, ligaments, bone.
What are reticular fibres?
Thin, branched collagen bundles with a glycoprotein coat. Provide support & strength, found in basement membranes, blood vessels, adipose tissue, nerves, smooth muscle.
What are elastic fibres?
Thinnest fibre, made of elastin + fibrillin. Can stretch up to 150%. Found in lungs, blood vessels, skin.
What is Marfan Syndrome?
A genetic defect in elastic fibres caused by a chromosome 15 mutation affecting fibrillin.
What are the symptoms of Marfan Syndrome?
Tall, long limbs, chest deformities, weakened heart valves, arterial walls (can be life-threatening).
What are fibroblasts?
Most common CT cells, secrete ECM (ground substance + fibres).
What are adipocytes?
Fat cells, store triglycerides, nuclei pushed to the side. Found around organs and under the skin.
What are macrophages?
Phagocytic immune cells that engulf bacteria and debris.
What are the types of fixed macrophages?
Kupffer cells (liver), Dust cells (lungs), Langerhans cells (skin).
What are plasma cells?
Derived from B-lymphocytes, produce antibodies.
What are mast cells?
Release histamine, found near blood vessels.
What are leukocytes?
White blood cells (e.g., lymphocytes, neutrophils, eosinophils).
What is mesenchymal CT?
Embryonic connective tissue, gives rise to all other CT.
What is mucous CT?
Found in the umbilical cord, jelly-like ground substance.
What are the three types of mature connective tissue?
Fluid CT (blood, lymph), Supporting CT (cartilage, bone), Proper CT (loose & dense).
What are the types of loose connective tissue?
Areolar, reticular, adipose.
What are the types of dense connective tissue?
Dense regular, dense irregular, elastic tissue.
What is areolar tissue?
Most common CT, bubble wrap-like, has all 3 fibre types (collagen, elastic, reticular).
What is reticular tissue?
Fine branching network found in liver, spleen, muscles, blood vessels.
What is adipose tissue?
Stores energy, insulates, regulates temperature. Two types: white (energy storage), brown (heat production).
What is dense regular tissue?
Collagen fibres in parallel bundles, found in tendons, ligaments. Little blood supply (slow healing).
What is dense irregular tissue?
Collagen fibres arranged irregularly, provides strength in multiple directions (found in dermis of skin).
What is elastic tissue?
Elastic fibres + fibroblasts, allows stretching & recoil (found in arteries, lungs, trachea).
What are the three types of cartilage?
Hyaline, fibrocartilage, elastic cartilage.
What is hyaline cartilage?
Most common cartilage, found in nose, trachea, ribs, ends of long bones. Provides flexibility & movement.
What is fibrocartilage?
Strongest cartilage, found in intervertebral discs.
What is elastic cartilage?
Contains elastic fibres, found in epiglottis, external ear.
What are the two types of bone tissue?
Compact bone (outer layer, strong), spongy bone (inner layer, trabeculae, contains marrow).
What is the function of osteoblasts?
Bone-forming cells, secrete ECM and initiate mineralization.
What is the function of osteocytes?
Mature bone cells, maintain bone tissue. Found in lacunae, communicate via gap junctions.
What is the function of osteoclasts?
Break down bone, large multinucleated cells derived from monocytes.
What is the function of canaliculi?
Small canals that allow exchange of nutrients, oxygen, and waste between osteocytes.
What are the four steps of bone healing?
- Osteoclasts resorb dead bone. 2. Chondroblasts lay down hyaline cartilage (callus). 3. Osteoblasts lay down new bone. 4. Osteoclasts remodel new bone.
What are the components of blood?
Plasma (ECM) + Formed elements (RBCs, WBCs, platelets).
What are erythrocytes (RBCs)?
Transport oxygen and carbon dioxide, no nuclei.
What are platelets?
Clotting function, derived from megakaryocytes.
What are the two classes of leukocytes?
Granular (eosinophils, basophils, neutrophils) and Agranular (monocytes, lymphocytes).
