Connective Tissue Flashcards

1
Q

What are some common features of connective tissues:?

A
  1. few cells (“hole” in ECM - lacuna)
  2. mostly ECM
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2
Q

What makes up the Extracellular Matrix (ECM)?

A
  1. ground substance
  2. protein fibers
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3
Q

What are the 3 types of protein fibers found in ECM?

A
  1. collagen (most common)
  2. elastic
  3. reticular
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4
Q

What determines the properties of the ECM and examples of this?

A

proportions
1. hard - calcified in bone
2. gel-like - loose connective in cartilage
3. fluid - in blood

(properties vary on how much you have of each protein fiber - bone vs ear)

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5
Q

Collagen fiber features:

A
  • high tensile strength
  • flexible
  • like a rope
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6
Q

Elastic fiber features:

A
  • low tensile strength
  • recoils
  • like a rubber band
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7
Q

What is the most abundant protein in the body?

A

collagen

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8
Q

What is the structure of collagen

A

triple helix structure (long thick rods)

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9
Q

How to build collagen?

A

chain -> triple helix -> colalgen fiber -> collagen fibril

  1. one polypeptide chain (primary)
  2. 3 chains into triple stranded collagen (triple helix)
  3. many triple helix come together to make a collagen fiber
  4. collagen fibril - lots of collagen fibers
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10
Q

What is ground substance made of?

A

proteoglycan molecules with glycosaminoglycan (GAG) chains (like bristles)

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11
Q

Why are you 1 cm taller in the morning than in the evening?

A

The negative charge of GAG chains in cartilage reacts with water and absorbs it throughout the night. As you walk around the water gets squeezed out and you get shorter.

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12
Q

Function of water in cartilage:

A
  1. add firmness to ground substance
  2. contribute to joint lubrication
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13
Q

What are two specialized cells found in cartilage?

A
  1. fibroblasts
  2. macrophages
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14
Q

What do fibroblasts do?

A

synthesis collagen & elastin fibers - secrete hyaluronic acid

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15
Q

What do macrophages do?

A

engulf damaged cells & pathogens

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16
Q

What are the non-universal categories of cartilage?

A
  1. General - loose & fibrous
  2. Specific - cartilage, bone, blood, hemopoietic tissue
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17
Q

What are the three types of loose connective tissue?

A
  1. mesenchyme
  2. adipose tissue
  3. areolar tissue
18
Q

What is mesenchyme tissue?

A

embryonic tissue
- gives rise to all other connective tissue
- mesenchymal cells (but no tissue) in adults

19
Q

What is adipose tissue?

A

store fat
- energy storage, padding, insulation

20
Q

What are the two types of adipose tissue and their functions/locations?

A
  1. energetic white fat (typical- belly, hypodermis)
  2. thermogenic brown fat (catabolism gives off heat - babies with small surface area to volume)
21
Q

What is areolar tissue?

A

“packing peanuts”
- cushion & support organs, nerves
- lots of collagen & elastin fibers
- in papillary layers of dermis

22
Q

What are the 2 types of fibrous connective tissue?

A
  1. dense regular - parallel collagen fibers
  2. dense irregular - strength and support from multiple directions
23
Q

What are three examples of dense regular connective tissues?

A
  1. aponeuroses
  2. ligaments (bone to bone - plywood)
  3. tendons (muscle to bone - rope)
24
Q

What are two examples of dense irregular connective tissues?

A
  1. periosteum (around the bone)
  2. reticular layer (suede inside of leather)
25
Q

What are the 3 types of cartilage?

A
  1. hyaline cartilage
  2. elastic cartilage
  3. fibrocartilage
26
Q

What are some locations of the 3 cartilage types?

A
  1. hyaline - ribs, joints of limbs, hip, nose
  2. elastic - ears, epiglottis
  3. fibro - spine discs, knees, pubic symphysis
27
Q

Describe hyaline cartilage

A
  • most common cartilage
  • relatively weak
  • forms embryonic skeleton (fontanelles)
28
Q

Describe elastic cartilage

A
  • elastic fiber is flexible & resilient
  • weakest
  • least common cartilage
29
Q

Describe fibrocartilage

A
  • in areas of high stress.
  • strongest
  • lots of collagen & little ground substance
30
Q

What are some of the main structures of bone? (6)

A
  1. Osteon made of
  2. Concentric lamella which have
  3. Osteocytes in
  4. Lacuna with
  5. Canalculi coming off
  6. Central/Haversian canal going through middle
31
Q

What are the characteristics of bone tissue?

A
  • few osteocytes
  • mostly hard, calcified matrix
32
Q

What are the components of the calcified matrix of bone?

A
  • bone is a composite tissue
    1. collagen - 1/3 - adds flexibility
    2. CaPO4 & CaCO3 - 2/3 - hard, but brittle
33
Q

What is the structure of bone matrix?

A

CaPO4 as crystals of hydroxyapatite and CaCO3 bound to collagen triple helix

34
Q

What are the types of bone cells? (3)

A
  1. osteoblasts
  2. osteocytes
  3. osteoclasts
35
Q

Describe osteoblasts

A

builds bone tissue matrix - get trapped in matrix (lacuna) become osteocyte

36
Q

Describe osteocytes

A

mature cell which maintains matrix

37
Q

Describe osteoclasts

A

break down bone matrix to be recycled - use HCL & lysosomes

38
Q

Why is the directionality of collagen fibers different between lamellae?

A

to prevent microwear and tear so it won’t continue all the way through osteon (like cracks in concrete)

39
Q

What connects central canals of one osteon to another?

A

Volkmann’s canals

40
Q

How does bone resist fracturing?

A
  1. bone is a composite material (collagen & CaPO4)
  2. collagen orientation changes (directionality of collagen fibers)