Tissues 1 Flashcards
Different shapes of epithelial cells
Squamous, cuboid, columnar, transitional
Purpose of stratified epithelium?
Protective role. More layers = more protective
How does epithelial tissue exchange gas?
They’re avascular so depend on diffusion for exchange
How are epithelial cells renewed?
Basal lamina divides, producing daughter cells which move up and mature as epithelial cells. The highest layers flatten as they degenerate.
Purpose of keratinising epithelia
found on stratified epithelia and protect the surface from abrasion and drying out
How is keratin formed on epithelial cells?
Basal cells divide and move up. Upon losing their nucleus and cytoplasmic organelles, they degenerate and become keratinising squamous cells.
What are the junctional complexes? (3)
Gap junctions allow ions to pass through adjacent cells.
Tight junctions hold adjacent cels together
Desmosomes connect cells-cells while hemidesmosomes connect a cell to the basal lamina
Example of Simple squamous?
Around vessels and the heart, with short diffusion distance
Example of Stratified squamous
Found in skin to withstand abrasion and prevent water loss. Can be keratinising
Example of Simple cuboidal
Salivary glands + kidney tubules, good for excretion due to thinness and high SA
Example of Stratified cuboidal
Rare - found in salivary ducts and sweat ducts - excretion
Example of Simple columnar
Lines stomach and intestinal tract. Has cilia (goblet cells) and microvilli (large SA). Main function is protection from bacteria
Example of Stratified columnar
Found in conjunctiva. Secretes mucus to protect
Example of Pseudostratified
Found in respiratory tract (trachea) for protection
Example of Transitional
Found in bladder as changes shape when moved
Whats the structure and make-up of loose connective tissue?
Elastin and Collagen fibres loosely arranged with fibroblasts and Adipocytes. Highly vascularised. All contained in Ground Substance
Whats the function of loose connective tissue?
Binds other tissues together and joins tissues into organs.
What is the ground substance?
Made of 90% water, a jelly like substance which contains tissue fluid for nutrient exchange and holds the fibres and supporting cells in place
What are supporting cells in the ground substance?
Fibroblasts, Adipocytes, White blood cells
What are fibroblasts and their structure?
Spindle-shaped nucleated cell which produces and secretes collagen
What are adipocytes?
Fat cells. Large lipid droplet with nucleus pushed to the side. Thought to have originated from Fibroblasts
White vs brown adipocytes?
White is larger, brown is smaller with many small lipid droplets and many mitochondria.
Where is adipose tissue found and its purpose?
Found underneath skin as fat for insulation. Also found surrounding organs. Stores energy.
What is fibronectin?
Found in CT cells. A fibre that helps supporting cells stick to the ECM/ ground substance
What makes up Dense Irregular CT?
Thick collagen fibres and elastin, very dense in all directions. Also has fibroblasts
Where is Dense Irregular CT found?
Dermis of skin to avoid skin abrasion, submucosa of digestive tract and organ/joint fibrous capsules.
What makes up Dense Regular CT?
Thick collagen, very little elastin in a highly ordered structure, All fibres go in one direction. Poor vascularisation
Where is Dense Regular CT found?
Joins tendons and ligaments.
