Connective Tissue

Question 1

What are the general features of connective tissue (CT)?

Answer 1

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.

Question 2

What are the main functions of connective tissue?

Answer 2

Support, protection, binding organs, energy storage (adipose tissue), transport (blood).

Question 3

What are the two main components of ECM?

Answer 3

Ground substance (GS) and fibres.

Question 4

What determines the properties of CT?

Answer 4

The composition of the ECM.

Question 5

How does ECM composition affect tissue properties?

Answer 5

Bone ECM is hard & rigid, while cartilage ECM is firm & rubbery.

Question 6

What is ground substance composed of?

Answer 6

Water, polysaccharides (GAGs), and proteins.

Question 7

What are glycosaminoglycans (GAGs)?

Answer 7

Unbranched polysaccharides with repeating disaccharide units.

Question 8

Why are GAGs hydrophilic?

Answer 8

They have negative charges, which attract positively charged ions and water.

Question 9

What are proteoglycans?

Answer 9

GAGs covalently bound to a core protein (mostly sugar).

Question 10

What are glycoproteins?

Answer 10

Proteins with sugar groups attached (more protein than sugar).

Question 11

What is the function of proteoglycans?

Answer 11

Maintain hydration and gel-like consistency in ECM.

Question 12

What are the types of sulphated GAGs and their locations?

Answer 12

Keratan sulphate (cartilage, cornea, bone), Chondroitin sulphate (cartilage, bone, skin, blood vessels), Dermatan sulphate (skin, tendons, heart valves, blood vessels), Heparin sulphate.

Question 13

What is the only non-sulphated GAG?

Answer 13

Hyaluronic acid.

Question 14

How is hyaluronic acid different from sulphated GAGs?

Answer 14

It does not bind to a core protein.

Question 15

What is the function of hyaluronic acid?

Answer 15

Viscous, slippery, binds cells together, maintains eyeball shape, lubricates joints.

Question 16

What is hyaluronidase?

Answer 16

An enzyme that breaks down hyaluronic acid.

Question 17

What is Exophthalmos?

Answer 17

Abnormal ECM deposition in the eyes due to autoimmune activation of fibroblasts.

Question 18

What causes Exophthalmos?

Answer 18

Increased GAG deposition in the eye leads to water retention and swelling.

Question 19

What are the three types of connective tissue fibres?

Answer 19

Collagen fibres, Reticular fibres, Elastic fibres.

Question 20

What are collagen fibres?

Answer 20

Thick, strong, flexible fibres that resist pulling forces. Most abundant protein (25% of body proteins). Found in cartilage, tendons, ligaments, bone.

Question 21

What are reticular fibres?

Answer 21

Thin, branched collagen bundles with a glycoprotein coat. Provide support & strength, found in basement membranes, blood vessels, adipose tissue, nerves, smooth muscle.

Question 22

What are elastic fibres?

Answer 22

Thinnest fibre, made of elastin + fibrillin. Can stretch up to 150%. Found in lungs, blood vessels, skin.

Question 23

What is Marfan Syndrome?

Answer 23

A genetic defect in elastic fibres caused by a chromosome 15 mutation affecting fibrillin.

Question 24

What are the symptoms of Marfan Syndrome?

Answer 24

Tall, long limbs, chest deformities, weakened heart valves, arterial walls (can be life-threatening).

Question 25

What are fibroblasts?

Answer 25

Most common CT cells, secrete ECM (ground substance + fibres).

Question 26

What are adipocytes?

Answer 26

Fat cells, store triglycerides, nuclei pushed to the side. Found around organs and under the skin.

Question 27

What are macrophages?

Answer 27

Phagocytic immune cells that engulf bacteria and debris.

Question 28

What are the types of fixed macrophages?

Answer 28

Kupffer cells (liver), Dust cells (lungs), Langerhans cells (skin).

Question 29

What are plasma cells?

Answer 29

Derived from B-lymphocytes, produce antibodies.

Question 30

What are mast cells?

Answer 30

Release histamine, found near blood vessels.

Question 31

What are leukocytes?

Answer 31

White blood cells (e.g., lymphocytes, neutrophils, eosinophils).

Question 32

What is mesenchymal CT?

Answer 32

Embryonic connective tissue, gives rise to all other CT.

Question 33

What is mucous CT?

Answer 33

Found in the umbilical cord, jelly-like ground substance.

Question 34

What are the three types of mature connective tissue?

Answer 34

Fluid CT (blood, lymph), Supporting CT (cartilage, bone), Proper CT (loose & dense).

Question 35

What are the types of loose connective tissue?

Answer 35

Areolar, reticular, adipose.

Question 36

What are the types of dense connective tissue?

Answer 36

Dense regular, dense irregular, elastic tissue.

Question 37

What is areolar tissue?

Answer 37

Most common CT, bubble wrap-like, has all 3 fibre types (collagen, elastic, reticular).

Question 38

What is reticular tissue?

Answer 38

Fine branching network found in liver, spleen, muscles, blood vessels.

Question 39

What is adipose tissue?

Answer 39

Stores energy, insulates, regulates temperature. Two types: white (energy storage), brown (heat production).

Question 40

What is dense regular tissue?

Answer 40

Collagen fibres in parallel bundles, found in tendons, ligaments. Little blood supply (slow healing).

Question 41

What is dense irregular tissue?

Answer 41

Collagen fibres arranged irregularly, provides strength in multiple directions (found in dermis of skin).

Question 42

What is elastic tissue?

Answer 42

Elastic fibres + fibroblasts, allows stretching & recoil (found in arteries, lungs, trachea).

Question 43

What are the three types of cartilage?

Answer 43

Hyaline, fibrocartilage, elastic cartilage.

Question 44

What is hyaline cartilage?

Answer 44

Most common cartilage, found in nose, trachea, ribs, ends of long bones. Provides flexibility & movement.

Question 45

What is fibrocartilage?

Answer 45

Strongest cartilage, found in intervertebral discs.

Question 46

What is elastic cartilage?

Answer 46

Contains elastic fibres, found in epiglottis, external ear.

Question 47

What are the two types of bone tissue?

Answer 47

Compact bone (outer layer, strong), spongy bone (inner layer, trabeculae, contains marrow).

Question 48

What is the function of osteoblasts?

Answer 48

Bone-forming cells, secrete ECM and initiate mineralization.

Question 49

What is the function of osteocytes?

Answer 49

Mature bone cells, maintain bone tissue. Found in lacunae, communicate via gap junctions.

Question 50

What is the function of osteoclasts?

Answer 50

Break down bone, large multinucleated cells derived from monocytes.

Question 51

What is the function of canaliculi?

Answer 51

Small canals that allow exchange of nutrients, oxygen, and waste between osteocytes.

Question 52

What are the four steps of bone healing?

Answer 52

1. Osteoclasts resorb dead bone. 2. Chondroblasts lay down hyaline cartilage (callus). 3. Osteoblasts lay down new bone. 4. Osteoclasts remodel new bone.

Question 53

What are the components of blood?

Answer 53

Plasma (ECM) + Formed elements (RBCs, WBCs, platelets).

Question 54

What are erythrocytes (RBCs)?

Answer 54

Transport oxygen and carbon dioxide, no nuclei.

Question 55

What are platelets?

Answer 55

Clotting function, derived from megakaryocytes.

Question 56

What are the two classes of leukocytes?

Answer 56

Granular (eosinophils, basophils, neutrophils) and Agranular (monocytes, lymphocytes).