LECTURE 2 (Connective Tissue II) Flashcards
What are the properties of Loose connective tissue/Areolar tissue?
- Contains cells, fibers and ground substance
- Delicate consistency
- Flexible
- Not very resistant to stress
What are the properties of Dense connective tissue?
- Fewer cells than loose connective tissue
- Mostly fibroblasts
- Mostly type I collagen fibers over ground substance
- Abundance protects organs and strengthens them structurally
What are the properties of Dense irregular connective tissue?
- Bundles of collagen fibers appear RANDOMLY interwoven with NO DEFINITE ORIENTATION
- Tough 3D network provides resistance to stress from all directions
- Dense irregular and loose connective tissue are closely associated
(EXAMPLES: deep dermis layer of skin & capsules surrounding most organs)
Describe Dense regular connective tissue
- Consists mostly of type I collagen bundles
- Collagen & fibroblasts aligned in parallel for great resistance to prolonged or repeated stresses from the SAME DIRECTION
(EXAMPLES: Tendons, aponeuroses & ligaments)
Why do dense regular connective tissue appear white in the fresh state?
They consist of densely packed parallel collagen fibers separated by very little ground substance and have very few blood vessels
Describe fibrocytes in relation to nuclei
Fibrocytes with elongated nuclei lie PARALLEL to the collagen fibers of DENSE REGULAR CONNECTIVE TISSUE with cytoplasmic folds enveloping portions of the collagen bundles
Describe Aponeuroses
The parallel bundles of collagen exist as multiple layers alternating at 90 degrees to one another
On their outer surface, tendons and ligaments have a layer of _________ _____________ connective tissue that is continuous with the outermost layers of the adjacent muscles and bones
Dense Irregular
What is the difference between Tendon and Aponeurosis?
TENDON:
- tough, rounded cord like structures (extensions of muscle)
- allow attachment of muscle from its originating bone to bone it ends
- has capacity to stretch & allow contraction of muscle by providing strength and support
APONEUROSIS:
- delicate, thin sheath-like structure attached muscles to bones
- property of recoiling
- muscle expands or contracts -> bears extra pressure and tension
What are the properties of reticular tissue?
- Abundant fibers of type III collagen
- Produced by modified fibroblasts (RETICULAR CELLS) that remain associated with and cover the fibers
- Cell-lined system creates a meshwork for the passage of leukocytes and lymph
- MACROPHAGES and DENDRITIC CELLS are disperse to monitor cells formed there or passing through and remove debris
What are the functions of Mucoid tissue?
- Component of FETAL UMBILICAL CORD
- Abundant ground substance & hyaluronan -> gelatinous with sparse collagen fibers and scattered fibroblasts
- Mesenchymal stem cells found in fibroblastic cells
What are the two types of Adipose tissue?
White adipose tissue & Brown adipose tissue
What are the similarities between the two types of Adipose tissue?
- Rich blood supply
- Adipocytes are individually surrounded by a thin external lamina containing TYPE IV COLLAGEN
What are the differences between the two types of Adipose tissue?
WHITE ADIPOSE TISSUE
- more common type specialised for fat storage
- consists of cells each containing one large cytoplasmic droplet of white-yellow fat
- mitochondrial metabolism releases ATP (energy) instead of heat
BROWN ADIPOSE TISSUE
- cells with multiple lipid droplets interspersed among abundant mitochondria
- darker appearance
- releases heat -> warms up the blood
What are the properties of White adipose tissue?
- Specialised for long-term energy storage
- Spherical when isolated but polyhedral when closely packed in situ
- Contains a single huge droplet of liquid filling the entire cell
- Signet ring appearance with lipid droplet displacing & flattening the nucleus against the cell membrane