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ZOO 3000 - Comparative Histology > Midterm Exam > Flashcards

Midterm Exam Flashcards

1
Q

What are the two types of intracellular substances?

A

Fibrous

Amorphous ground substance

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2
Q

What is the function of fibrous intracellular substances?

A

Strength and support - polypeptide chains

main type = collagen fibres

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3
Q

What are some morphological aspects of collagen fibres?

A

white in flesh state
form insoluble tannic acid after treatment with heavy metal - tanning which turns collagen to leathery sheet
three polypeptide chains of procollagen
aggregate to form 1-12 micrometer fibrils

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4
Q

What synthesizes and secretes collagen fibres?

A 
fibroblasts
chondrocytes
osteoblasts
epithelial basement membrane 
etc
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5
Q

Where are collagen fibres particularly abundant?

A

ECM, especially connective tissue

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6
Q

Why are collagen fibres so tough?

A

covalent H-bonds are formed between adjacent rows of molecules

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7
Q

What makes up the majority of tendons?

A

lined up bundles of collagen

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8
Q

what synthesizes and secrets reticular fibres?

A

Fibroblasts and other cells

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9
Q

What are some differences between reticular fibres and collagen fibres?

A

contain more sugar

do not bundle as much as type 1 collagen fibre

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10
Q

What are some morphological features of reticular fibres?

A

made of type 3 collagen with more sugars
stains with silver
typically 20 nanometer fibrils
stain with periodic acid-schiff (structure rich in sugar)
quite tough due to cross linking (similar to collagen)

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11
Q

What is the function of reticular fibres?

A

Supportive scaffolding, bridge transition to type 1 collagen

forms a net like support framework –> reticulum

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12
Q

What are the two main components of elastin fibres?

A

bundles of protein = elastin, rich in proline and glycine

Glycoproteins such as fibrillin which organizes into microfibrils

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13
Q

What are some morphological features of elastin fibres?

A

Yellow in fresh state
Sheets of fibres and networks
stain darker, thinner and more abundant than collagen which stain lighter and thicker
ribbons of microfibrils usually 1-4 micrometers

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14
Q

what binds ribbons of elastin fibrils covalently?

A

desmosine

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15
Q

What is the function of elastin fibres?

A

stretching and distension

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16
Q

Where are elastin fibres found?

A

Ligaments, larynx and some arteries

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17
Q

What is the purpose of the link between fibrils of elastin fibres?

A

allows fibrils to maintain their integrity during stretch and recoil

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18
Q

What secretes and synthesizes elastin fibres?

A

fibroblasts and smooth muscle cells

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19
Q

What are some morphological features of amorphous ground substance?

A

Viscous, clear, slippery
Viscosity varies with amount of cross linking
altering negative charge can also alter viscosity - lower neg charge in eye than bone in leg

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20
Q

What synthesizes and secretes amorphous ground substance?

A

fibroblasts

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21
Q

What are the components of amorphous ground substance?

A

Proteins, glycoproteins and carbs
glycosaminoglycans (GAGs) - repeating disaccharide units that are negatively charged and attract water (gel-like, major component)
proteoglycans - glycosaminoglycans attached to proteins
multi-adhesive glycoproteins - fibronectins and laminins which link to cell surface and regulate cell movement
hyaluronic acid - long, rigid, bound to proteins to form proteoglycan aggregates

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22
Q

what is the function of amorphous ground substance?

A

soft, fluid-like –> aids diffusion of tissue fluids

Firm gel-like –> resists more compression

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23
Q

Where are the different kinds of amorphous ground substances found?

A

Soft –> tissues, humours of the eye

Gel –> synovial fluid in joints, cartilage

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24
Q

Where is tissue fluid derived from?

A

Source = blood

hydrostatic pressure at arterial end of capillaries

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25
Q

What does tissue fluid consist of?

A

Water, salts, nutrients, hormones and oxygen

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26
Q

How is tissue fluid returned?

A
  1. Capillary absorption via osmosis and pinocytosis

2. lymphatic absorption - very permeable

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27
Q

What are the four primary tissues?

A

Epithelium - Cells closely apposed, little ground substance, sheets covering and lining surfaces
Connective tissue - Cells widely spread, variable amount of ECM, abundant collagen fibrils
Muscle tissue - elongated contractile cells, closely associated, skeletal and smooth
Nervous tissue - cells with elongated processes, specialized electrical impulses

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28
Q

What did the innovation of eumetazoa allow for?

A

Compartmentalization: New intracellular compartments
-coelenteron, mesoglea, excretion
physiological regulation and specialization:
- digestion, transport, of nutrients and gases, excretion

29
Q

What innovation came before epithelium and how was it different from true epithelium?

A

Epitheloid (porifera and placazoa)

- relatively loose and not resting on anything (still close together)

30
Q

How did epithelium evolve?

A

Cnidarians and ctenophora: cells rest on basal lamina of laminin and type 4 collagen
Bilateria: cells rest on basal lamina also in coelom and allows for a distinct circulation system

31
Q

What are the basic morphological features of epithelium?

A

sheets of cells arranged in either single (simple) or multiple layers (stratified)
covers and lines surfaces and cavities

32
Q

What is the function of epithelium?

A

Selective barrier - mechanical resistance
Secretory - enzymes, mucus and hormones
Absorption - facilitated diffusion, creates gradient
transport - pinocytosis/ exocytosis
sensory - specialized epithelium such as the retina

33
Q

How is integrity of the epithelium maintained?

A

Laterally via intercellular bridges and junctions known as junctional complex of terminal bar
Basally via junctions to the basement membrane

34
Q

What are the three kinds of junctions found in the intercellular bridges of epithelium?

A
  1. Tight occluding junctions ZO (zonula ocdudens)
    - contain several transmembrane proteins
    - establishes diffusion barrier to water
    - establishes functional domains in plasma membrane
  2. Anchoring junctions (ZA and MA)
    - ZA: attach to actin via vinculin-actinin - removal of calcium leads to dissociation
    - MA/desmosomes: attach to intermediate filaments by attachments plaques, mechanical stability and force dissipation by linking cytoskeleton of cells
    - calcium trigger cadherin zipper binding
  3. Gap junctions
    - connexins: proteins that make up channels which line up and may react to messages to change their conformation (open/close)
    - direct communication between cells –> ions, amino acids and metabolites
    - coordinate activity between cells
35
Q

What three layers make up the basement membrane of epithelium?

A
  1. lamina lucida: cell coat, protein linkers (integrin) between cytoskeleton and lamina densa
  2. lamina densa (basal lamina): cross linked proteoglycans, type four collagen and laminins
  3. Reticular lamina: network of reticular fibrils attached via anchoring fibril loops, type 3 collagen
36
Q

What are the function of the basement membrane?

A
  1. Structural attachment between epithelium and ct
    - anchored by hemidesmosomes and focal adhesions ( cell to ECM anchoring junctions)
  2. Compartmentalization
    - basal lamina separates epithelium and ct
  3. Filtration
    - Ionic charge in basal lamina plays a role in kidney ultrafiltration - neg charge allows certain molecules to pass
  4. Regulation and signalling
    - influencing epithelial cell shape, proliferation, differentiation, motility during development and regeneration
  5. Tissue scaffolding
    - Basal lamina guides new cells or processes during regeneration
37
Q

What are the three(actually 4) types of epithelia?

A
  1. Squamous - Width greater than height
    2, Cuboidal - Equal width, depth, height
  2. Columnar - Height greater than width
  3. Pseudostratified epithelium(RARE) - nuclei at different levels, but all rest on basement membrane
38
Q

What is endothelium and mesothelium?

A

Simple squamous: epithelia lining blood vessels and covering organs respectively

39
Q

What is the function of stratified epithelia?

A

Protection against friction or shearing eg. skin epidermis

40
Q

What are the four types of stratified epithelia?

A

Stratified squamous epithelium - superficial layer squamous
Stratified cuboidal - sup layer cuboidal
Stratified columnar - sup layer columnar
Transitional epithelium - sup layer changes w/ distension eg. urinary bladder

41
Q

What is the difference between cilia and microvilli?

A

Both increase SA for exchange
Cilia are much larger
Cilia have microtubules inside that allow for motility
Microvilli have actin filaments for support, not motile

42
Q

What are some examples of the earliest forms of CT?

A

Mesohyl of sponges
Mesoglea of cnidarians and ctenophores
Coelom walls of bacteria allowing for more specialization

43
Q

What are the three main components of CT

A

Cells
Fibrous components
Amorphous intracellular ground substance

44
Q

How and why is CT the primary tissue?

A

Morphology - separation between cells

Continuous compartment and distinct functions vs. other primary tissues

45
Q

What are the prominent resident cells of CT?

A

Fibroblasts
Mast cells
Macrophages
Adipose cells (large, white)

46
Q

What are the morphological features of fibroblasts?

A

Shape- fusiform, spindle shaped
Nucleus - oval/elongate, stain dark
Cytoplasm - homogeneous, weakly basophil (stain light)

47
Q

What is the function of fibroblasts?

A

Synthesis of fibrous components and ground substance

48
Q

What are the morphological features of mast cells?

A

Shape - irregular oval
Nucleus - Spherical but inconspicuous
Cytoplasm - large #of basophilic granules
Can clearly see nucleus and surrounding membrane

49
Q

What is the function of mast cells?

A

Secrete granules containing the following mediators of inflammation in response to allergens

  • hesparin
  • histamine
  • eosinophil and neutrophil chemotactic factors
50
Q

What are the morphological features of macrophages?

A

Shape - ovoid (wondering) to stellate (fixed), shape is variable and depend on activity
Nucleus - kidney shaped
Cytoplasm - dark w/ small granules, lysosome present

51
Q

What is the function of macrophages?

A

Phagocytosis and participate in immune response
“antigen-presenting cells”
Engulf foreign materials, bring them into cytoplasm and digest/ break into small parts that are trafficked to the membrane and signal communication to other cells and begin immune response

52
Q

What are the morphological features of adipose cells?

A

Shape - spherical, ovoid
Nucleus - flattened against periphery
Cytoplasm - Thin layer around fat globule

53
Q

What is the function of adipose cells?

A

Store lipids and release when needed, mechanical protection, temperature control, secrete hormones such as liptin which is involved in energy balance regulation

54
Q

What are the transient cell populations of CT? *predominantly blood cells

A 
Plasma cells * most abundant form of ct 
Lymphocytes 
Eosinophils
Monocytes 
*these three are rare but abundant during acute inflammation
55
Q

What are the morphological features of plasma cells?

A

Shape- ovoid
Nucleus - spherical and small
Cytoplasm - basophilic around golgi apparatus which indicates high metabolic activity in this region

56
Q

What is the function of plasma cells?

A

Production of a specific antibody - must be activated

57
Q

Types of connective tissue proper

A

Loose connective tissue
Dense connective tissue
*differentiated by proportions of cellular, fibrous and amorphous components

58
Q

What are some general features of loose ct?

A

Glandular tissue is surrounded by white -> fewer bundles of collagen and purple nuclei

59
Q

What are some examples of loose connective tissue?

A 
Mesenchyme
Mucoid ct
areolar ct
adipose tissue (white or brown) 
reticular tissue
60
Q

What are the features and functions of mesenchyme?

A 
fetal tissue, embryonic ct
sparse collagen and fibroblasts 
cells are pluripotent 
Source for all connective ct 
loose and irregular
61
Q

What are the features of mucoid ct and where is it found

A

embryonic ct found un umbilical cord

Contains: stellate fibroblasts, jelly-like mucous gland substance, mesenchymal stem cells

62
Q

What are the features of areolar ct and where is it found?

A

Beneath epithelia and around small blood vessels

Contains: all major cell types, abundant ground substance, collagen and elastin fibres

63
Q

What are the features of white vs. brown adipose cells?

A

White: unilocular or multilocular cells, reticular fibre network surrounding cells, sparse supply of capillaries
Brown: multilocular cells, sparse reticular fibres between cells, rich supply of capillaries, heat production function

64
Q

What are the features of reticular tissue and where is it found?

A

Fine and loose supportive cells
made of type 3 collagen sometimes wrapped around by specialized reticular cells
found in the liver, spleen, lymph nodes, bone marrow and in adipose tissue

65
Q

What is the function of dense ct and how is it able to perform this function?

A

Resist stretching and provide strength

Proportionately large amount of fibrous elements

66
Q

What are the different kinds of dense ct, where are they found and what are their features?

A

dense irregular ct: abundant collagen fibres arranged in irregular directions, found in the capsule of organs and the dermis (strength to skin)
dense regular ct: collagen fibres are regularly arranged, found in tendons, ligaments and cornea

67
Q

What is the difference between the ECM of cartilage vs. bone?

A

ECM of cartilage has highly charged proteoglycan aggregates making it hard and pliable - much more flexible than in bone
ECM of bone is calcified via CaPO4 which makes it hard and rigid

68
Q

How does cartilage develop?

A

develops from mesenchyme that condenses to form cartilage and initial skeletal structure –> the chondrogenic nodule
Most becomes ossified and replaced by bone
mesenchyme cells differentiate into chondroblasts which secrete cartilage matrix and becomes enclosed in small cavities called lacunae
Chondroblasts become chondrocytes which divide and produce more ground substance and fibres

ZOO 3000 - Comparative Histology (1 decks)

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