Study your flashcards anywhere!

Download the official Cram app for free >

  • Shuffle
    Toggle On
    Toggle Off
  • Alphabetize
    Toggle On
    Toggle Off
  • Front First
    Toggle On
    Toggle Off
  • Both Sides
    Toggle On
    Toggle Off
  • Read
    Toggle On
    Toggle Off
Reading...
Front

How to study your flashcards.

Right/Left arrow keys: Navigate between flashcards.right arrow keyleft arrow key

Up/Down arrow keys: Flip the card between the front and back.down keyup key

H key: Show hint (3rd side).h key

A key: Read text to speech.a key

image

Play button

image

Play button

image

Progress

1/19

Click to flip

19 Cards in this Set

  • Front
  • Back

What are the four main different types of tissue?

- Epithelial


- Muscle


- Connective


- Nerve

Connective tissue generally has two different categories in terms of shape and mechanical properties:

- pulling and stretching




- twisting and squashing

Connective tissue is broadly divided into four categories:

- Blood




- Bone (compact and spongy)




- Cartilage (hyaline, fibrocartilage, elastic)




- Connective tissue proper (loose and dense)

What are the different types of loose connective tissue proper:

- Areolar - holds organs together, underlying epithelial tissues, blood vessels, nerves




- Adipose




- Reticular - composed of reticular fibres, found in the spleen, liver and lymph nodes

What are the different types of dense connective tissue proper:

- Regular - the collagen fibres run in the same diraction, such tssue has a very high tensile strength (tendon)


- Irregular - less regularly arranged collagen fibres giving strength in all direction (dermis)


- Elastic - in this tissue, elastin is the main fibre type; an example of this is found in the vocal fold

What are the main characteristics of connective tissue?

- Abundance of extracellular matrix




- Cells are normally separated by ECM

Examples of connective tissue in other phyla:

- chitin exoskeleton in insects - main support




- connective tissue layers surrounding many organs




- CT attaching Malpighian tubules to the gut

What are the functions of connective tissues?

- Join the other tissues of the body


- Mechanical support to organs


- take the stress of movement


- maintain shape


- growth, development and repair

What is the extracellular matrix?

- A composite of insoluble fibres and soluble polymers

What are the three principle components of the ECM?

- Collagen - confer tensile strength




- Proteoglycans - confer resiliency and compressibility




- Matrix glycoproteins - elasticity, tissue cohesiveness & cell-ECM communication

What are the features of collagen?

- a family of ~29 fibrous proteins that share a common motif - trible helix


- 3 polypeptides (α chains) intertwine to form a rod-shaped super-helix


- type I collagen is the major collagen in CT

What are the features of type I collagen?

- high abundance of Glycine, Proline and Hydroxyproline




- Gly-X-Y repeating motif




- triple helix stabilised by hydrogen bonds




- denatured collagen - gelatin

What post-translational modifications does collagen go through:

1) hydroxylation of proline (ascorbate is essential co-factor = keeps enzyme in active/reduced state)


2) hydroxylation of lysine


3) glycosylation


4) lysyl oxidase - initiation of collagen cross links

What is the role of hydroxyproline residues?

- stabilize the triple helix by increasing hydrogen bonds between α chains




- more hydroxyproline = more hydrogen bonds = higher melting temperature

How do α chains fold into a triple helix?

- initiated by C-terminal propeptide - alignment




- folds from the C terminal towards the N terminal

Propeptides in the ECM are cleaved:

- Converting soluble procollagen to insoluble collagen triple helical rods




- cleavage of the C and N terminal propeptides




- The cleavage is mediated by C and N proteinases

How is type I collagen assembled (from molecules to fibrils)?

- Three precursor chains assemble into triple helix with loose ends (procollagen)


- procollagen peptidase = collagen


- assembly of collagen into fibrils - adjacent molecules are displaced approximately 1/4 of their length = striated appearance seen in electron microscope


- Collagen fibrils aggregate side-by-side in bundles into fibres

How is type I collagen assembled (image)?

How does collagen cross-linking take place and what is the purpose of it?

- initiated by oxidation of lysine or hydroxylysine residues by lysyl oxidase




- stabilizes collagen fibrils