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Histology (Fall) > Chandra > Flashcards

Chandra Flashcards

1
Q

Eosin stain

A

Negatively charged pink stain with a carboxyl group

Binds to acidophilic tissues

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2
Q

Basophilic tissues

A

Negatively charged tissues that attract positively charged hemotoxylin stain
Structures such as DNA, rna, rer, ribosomes.

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3
Q

Hemotoxylin

A

Blue, positively charged metal (al3+) complex stain.

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4
Q

Endocytosis

A

Bulk intake of material
Calveolae pinch off and form vesicles causing plasma membrane loss
Non-specific - typically for fluids and ions

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5
Q

Clathrin

A

Proteins that cover calveolae and assist in vesicle formation in endocytosis

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6
Q

Calveolae

A

Little pits in the plasma membrane, coated in clathrin

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7
Q

Dynein

A

Protein that “walks” along microtubules to transport vesicles to the lysosomes.

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8
Q

Receptor mediated endocytosis

A

Specific transport of molecules into the cell. Caused by ligands binding to receptors and driving vesicle formations.

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9
Q

Exocytosis

A

Excretion via vesicles. Vesicles = membrane recycling after endocytosis.

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10
Q

Kinesin

A

Protein that “walks” along microtubules to transport a vesicle to the plasma membrane.

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11
Q

Nucleus

A

Basophilic
Largest cell organelle
Typically 1 but can be 2 (cardiac) or many (skeletal muscle)
Typically round but can be lobed or kidney shaped.

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12
Q

Euchromatin

A

Loose, active chromosomal material

Lightly basophilic

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13
Q

Heterochromatin

A

Tightly coiled inactive chromosomal material
Strongly basophilic
Often seen in course granules

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14
Q

Nucleolus

A

Highly active region of the nucleus transcribing ribosomal RNA
Stains highly basophilic
Strongly prominent in highly active cells

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15
Q

Acidophilic tissue

A

Positively charged tissues that attract negatively charged eosin stain
Typically protein filled cytoplasm

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16
Q

Ribosomes

A 
Strongly basophilic (from rRNA)
Free polyribosomes: create proteins for intracellular use (Hgb)
Or anchored in the rough endoplasmic reticulum: proteins for extracellular use or to be used inside membrane bound organelles (lysosomes)
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17
Q

Rough Endoplasmic Reticulum

A

Continuous with the nucleus
Protein synthesis of excreted or membrane bound proteins.
Also assists in post-translational modification of proteins and transport of proteins.

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18
Q

Smooth Endoplasmic Reticulum

A 
Functions: 
Drug detoxification (in hepatocytes)
Synthesis of steroid hormones
Synthesis of phospholipids
Synthesis of cholesterol
Synthesis of Vitamin D
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19
Q

Golgi Complex

A

Does post-translational modification of proteins (esp glycosylation and phosphorylation) and packs secretory protein in vesicles.
Lipid membrane stains badly creating a NEGATIVE GOLGI IMAGE.

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20
Q

Lysosomes

A

INTRACELLULAR digestive system of both proteins and foreign bodies. Filled with hydrolytic enzymes from proton pumps in the membranes of the lysosome.

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21
Q

Why do erythrocytes stain differently than reticulocytes?

A

Reticulocytes are full of free polyribosomes that are producing hemoglobin, and so is lightly basophilic. After enough Hgb has been made and the reticulocyte matures to a erthryocyte, ribosomes are degraded and the high levels of Hgb protein in the cell causes acidophilic staining.

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22
Q

How often are erthrocyytes replaced?

A

Every 80-90 days.

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23
Q

What is special about the staining of pancreatic acing cells and why does this occur?

A

The basal half of the cell is basophilic and the apical region is acidophilic. These cells are secretory cells of digestive enzymes. Thus, the basal side is basophilic due to high amounts of RER, and the the proteins being produced stain acidophilic and move towards the apical region of the cell to be released.

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24
Q

How do fibroblasts stain and why?

A

Basophilic
Large amount of RER for making and exporting collagen.
Euchromatic nuclei.

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25
Q

In which cells do you see an obvious negative golgi image?

A

Villi and epithelial cells.

Plasma cells.

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26
Q

Two types of phagocytic cells

A

Neutrophils and macrophages

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27
Q

Autophagosome

A

Damaged cellular material such as proteins contained in the membrane-bound lysosome.

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28
Q

Heterophagosome

A

Foreign bodies such as bacteria contained in the membrane-bound lysosome.

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29
Q

Lipofuscin granule

A

Result of a lysosome’s failure to completely removed digested material, often from an imbalance in the disposal mechanism. Buildup of these associated with age and can cause liver/neurodegenerative diseases.

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30
Q

Primary lysosome

A

A lysosome that has not yet entered a digestive event.

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31
Q

Secondary lysosome

A

A lysosome that has already become a phagosome by combining with material to be removed, and started to digest that material.

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32
Q

Mitochondria

A

Stain acidophilic

Source of the cell’s chemical energy

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33
Q

What are some reasons we might see a lot of mitochondria in a cell?

A

Cell is producing steroids
Highly energetic cell (i.e. muscle)
Cell is synthesizing or breaking down fat
Cell moves ions against a gradient and needs ATP for that.

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34
Q

How do we recognize the mitochondria in electron microscopy?

A

Cristae - folds of the inner membrane of the mitochondria.

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35
Q

Mitochondrial myopathy

A

See enlarged mitochondria with spiraled christae - leads to eventual cell death.

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36
Q

Cytoskeletal components

A

Microtubules
Actin (or microfilaments)
Intermediate filaments

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37
Q

Functions of the cytoskeleton

A 
Establish cell shape
Provide mechanical strength for the cell
Chromosomal separation in meiosis and mitosis
Intracellular transport of organelles 
Movement of the cell.
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38
Q

Microtubules

A

Made and disassembled rapidly.
Tube of alternating alpha and beta dimers
The largest cytoskeletal element
Form spindles in cell division
“highway” for kinesin and dynein to transport materials around the cell.

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39
Q

Microfilaments

A

Made and disassembled rapidly
Made of actin
Helically intertwined chains.
Mostly used for muscle contraction, cell division, and cell motility but does play a role in material transport in the cell as well.

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40
Q

Intermediate filaments

A

HIGHLY STABLE

Prevalent in tissues that must withstand mechanical stress such as skin.

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41
Q

What are the phases of the cell cycle and what is going on in each of them?

A

G1: Part of interphase. RNA and protein synthesis.
G0: Part of interphase. Resting state. G1 + G0 = 25 hours.
S: DNA replication. Cell is now committed to mitosis.
G2: Microtubule assembly.
M phase: Cell division

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42
Q

What type of cells are constantly mitotic?

A

Certain epithelial cells.

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43
Q

What types of cells are non-mitotic? What phase of the cell cycle are they in?

A

Muscle and nerves. Arrest permanently in the G0 phase.

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44
Q

What types of cells are intermittently mitotic?

A

Liver cells.

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45
Q

What are the phases of cell division? What does the genetic material look like in each?

A

Prophase: no defined nucleus, appears circular
Metaphase: Clear distinct band of genetic material in the middle of cell.
Anaphase: 2 distinct bands of genetic material.
Telophase: Two rounder bands of material with division in the membrane appearing between them.

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46
Q

Prophase

A

Nuclear membrane disperses
Centrosomes appear at opposite sides of the cell
Mitotic spindles form
Chromosomes become visible and condensed. All material is still in ball in the center of the cell.

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47
Q

Metaphase

A

Chromosomes arrange into a band in the center of the cell, kinetochore binds to microtubule.

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48
Q

Anaphase

A

Sister chromatids separate from each other to separate towards opposite sides. Motor proteins pull microtubules using ATP.

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49
Q

Telophase

A

Division in the membrane appears (cytokenesis). Nuclear membrane reappears, spindle apparatus disappears

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50
Q

Cytokenesis

A

Constriction of the cell membrane. Actin filaments using myosin type proteins pull together to separate the two cells. Organelles and proteins will split randomly but relatively evenly.

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51
Q

Crypts of lieberkuhn

A

Mitotic cells at the bottom of microvilli. Make new cells and then push them up the structure.

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52
Q

Three domains of epithelial cells

A

Basal: on the basement membrane
Lateral: Contacting adjacent epithelial cells
Apical: facing the lumen, free surface, or external space

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53
Q

Why is the basement membrane important to the epithelium?

A

Epithelial tissue is avascular

Depends on connective tissue for nutrients and waste removal. Bsmt membrane provides with both.

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54
Q

Two parts of the basement membrane

A 
Basal lamina (superficial)
reticular lamina (deep)
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55
Q

4 modifications of the lateral domain of epithelial cells.

A

Tight junctions
Belt Desmosomes
Spot Desmosomes
Gap junctions

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56
Q

Tight junctions

A

Zona occludens. Just below the apical surface of the cells, serves to waterproof them against a harsh external/lumenal environment.

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57
Q

Belt desmosomes

A

Zonula adherens. Keeps epithelial cells together tightly (think of a 6 pack soda can plastic thingy)

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58
Q

Spot desmosomes

A

Macula adherens. Randomly placed on the lateral sides - points of attachment for the cytoskeleton of the cells, especially in skin.

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59
Q

Gap junctions

A

Tiny pores between cells for the passage of nutrients and waste. 100s per cell.

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60
Q

Three specializations of the apical domain of epithelial cells.

A

Microvilli - increase SA for absorptions
Sterocilia - also increase SA for absorption (non-motile). Important in hearing and balance.
Cilia - Move substances over/around the cell with undulating movement. Trachea and oviduct.

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61
Q

Striated border

A

Also called brush border. Microscopic thick border over the apical surface of a cell when microvilli or sterocilia are present. Stains acidophilic because fingers of material trap proteins inside. Receptor proteins in microvilli and stereocilia add to acidophilia of border.

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62
Q

Primary epithelium

A

Covers all external and internal surfaces of the body (skin, inside and outside of organs, blood vessels, GI and respiratory tracts).

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63
Q

Secondary epithelium

A

Glandular epithelium. Develop from pockets of the epithelium. Both small glands and glandular organs (kidney, pancreas, etc.)

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64
Q

Simple epithelium

A

Single layer of cells

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65
Q

What are the three classifications we use to name epithelium?

A

Number of layers
Morphological features of surface layer
Cell shape (or top layer cell shape)
None of these will be SPECIFIC to function but might hint at the cell function.

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66
Q

Squamous cells

A

Flat and somewhat square. Nucleus central because it is trapped in the widest part of the cell which is the center.

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67
Q

Mesothelium

A

Simple squamous epithelium. Covers the serous cavities of the body (including the outside of blood vessels) and produces a lubricating fluid which is protective and facilitates intracoelomic movement.

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68
Q

Endothelium

A

Simple squamous epithelium that lines the lumen of the circulatory system (all, including heart and lymph). Flatness allows a rapid exchange of gases and nutrients between the blood and tissue.

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69
Q

Simple cuboidal epithelium

A

Found in the ducts of glands and the collecting ducts of the kidneys. Not actually secreting or absorbing anything so no need to be long or flat. To ID, look for a distinct lateral border between cells in slide. Centrally located nucleus.

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70
Q

Simple columnar epithelium

A

Nucleus oval and near the basal side of the cell. Found in areas with secretory functions because they have a large amount of cytoplasm. Often have microvilliated or stereociliated brush borders.

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71
Q

Pseudostratified columnar epithelium

A

Looks stratified but is not, often due to presence of goblet cells that don’t reach the apical surface or uneven basement membrane. Usually ciliated and most often found in the respiratory tract, as well as in the oviduct.

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72
Q

Stratified epithelial specializations

A

Keratin, many gap junctions to keep all layers of cells alive.

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73
Q

What is the shape classification of stratified epithelium based on?

A

The most superficial layer of the epithelium. This may be different than the shape of the cells beneath it.

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74
Q

Stratified keratinized squamous epithelium

A

Skin or protective layer (esophaguses of herbivores). Surface layers have lost nuclei (died) and are full of keratin.

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75
Q

Stratified nonkeratinized squamous epithelium

A

Generally wet areas with high occurrence of wear and tear.

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76
Q

Stratified cuboidal epithelium

A

Found in the larger excretory ducts of glands such as the salivary and mammary glands.

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77
Q

Stratified pseudokeratinized squamous epithelium

A

Keratin produced but some nuclei remain in the cells trapped in the keratin retain their nucleus. Generally found between keratinized and non-keratinized areas like the lips. Can also be a sign of disease state such as psoriasis or nutrient deficiency.

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78
Q

Stratified transitional epithelium

A

In areas that have to stretch. Usually many types of cells. Random before stretching, lengthened when stretched. Bladder wall, etc.

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79
Q

What are the steps to create a gland from secondary epithelium

A
  1. Epithelial cells begin to multiply in one area.
  2. Cells proliferate down into connective tissue.
  3. Some maintain a duct (exocrine glands)
  4. Some lose duct but have access to a blood vessel - release things to the interstitial space and they are transported into the blood (endocrine glands).
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80
Q

What are the two major categories of glandular epithelium?

A 
Unicellular glands (ex. goblet cells)
Multicellular glands (ex. sebaceous gland)
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81
Q

Types of exocrine glands

A

Serous (watery)
Mucous (slimy)
Mixed (Serous and Mucous)

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82
Q

Pancreatic acinar glands and partotid glands are what type of glands?

A

Multicellular serous glands

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83
Q

Goblet cells are what type of gland? Where do you find them primarily?

A

Unicellular mucous glands.

Found primarily in the trachea and the intestines.

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84
Q

What type of glands are mandibular salivary glands?

A

Multicellular mixed glands

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85
Q

What are the exocrine gland modes of production?

A

Merocrine: Cells remain intact
Apocrine: Fragments of the cell bud off.
Holocrine: Secretion of the whole cells.

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86
Q

Give an example of a merocrine cell.

A

Dog footpad sweat glands or pancreatic acinar cells.

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87
Q

Give an example of an apocrine cell.

A

Axilla sweat glands of humans or sweat glands of hair covered portions of animals.

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88
Q

Give an example of a holocrine cell.

A

Sebaceous glands.

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89
Q

What would a merocrine gland look like on a slide?

A

Targetlike - basophilic region on the outside of the gland and acidophilic region on the inside of the gland with a duct on the inside of the gland.

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90
Q

What would an apocrine gland look like on a slide?

A

Fragmented pieces of cell in the lumen.

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91
Q

What would a holocrine gland look like on a slide?

A

Foamy or spongy appearance.

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92
Q

Functions of connective tissue

A 
Mechanical (supports body components)
Nutritional (metabolite exchange matrix)
Storage (of energy as fat) 
Defense (by immune cells in CT)
Repair (regenerative capacity to heal injuries).
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93
Q

Types of cells in the the connective tissue matrix?

A 
Fibroblasts
Fibrocytes
Macrophages
Plasma cells
Mast cells
Adipose cells
Reticular cells
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94
Q

Fibroblasts

A

Very actively synthesizing and secreting substance that makes up the extracellular fibrous matrix. Lightly basophilic cytoplasm (RER), and ovoid, thick, euchromatic nuclei. Synthesis Type I collagen (large and ropelike).

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95
Q

Fibrocytes

A

Less active version of a fibroblast. Smaller, thinner, heterochromatic nucleus and thinner cell in general. Find in more mature parts of connective tissue.

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96
Q

Macrophages

A

Derived from monocytes. Difficult to distinguish from fibroblasts often. Large, ovoid or spherical cells with a foamy cytoplasm or oval or kidney shaped ECCENTRIC nucleus. Easiest to see in slides stained with India ink because they will digest the ink. Phagocytize cells and secrete substances for defense and repair.

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97
Q

Plasma cells

A

Develop from B-lymphocytes
Large numbers in CT of intestinal mucosa.
Responsible for synthesis of antibodies.
Ovoid to spherical with round ECCENTRICALLY located nucleus - cartwheel pattern from patches of euchromatin and heterochromatin.
Intensely basophilic cytoplasm from RER.

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98
Q

Mast cells

A

Numerous along small blood vessels. Packed with basophilic granules that stain METACHROMICALLY - stains in such a way that it is different than the stain that is put on it.
Synthesize histamine and heparin - chemical mediators of the inflammatory response.

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99
Q

Adipose cells

A

Always in groups.
Nucleus pushed eccentrically by fatty material.
Artifactually appear empty in slides because ethanol destroys lipids.

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100
Q

Reticular cells

A

Modified fibroblasts that secrete collagen type III. Fine fibers that form a spongelike tissue in the lymphatic tissues. Arygylophilic - attract silver so use a silver dye to stain the fibers.

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101
Q

Histamine

A

Inflammatory response, released by mast cells. Causes vasodilation to increase the permeability of blood capillaries.

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102
Q

Heparin

A

Inflammatory response, released by mast cells. Anticoagulant.

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103
Q

Composition of the extracellular matrix of connective tissue.

A

Fibroblasts, fibrocytes, protein fibers (collagen, elastic, and reticular), and ground substance.

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104
Q

What is the most abundant protein in the body?

A

Collagen type I

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105
Q

What type of structures consist of collagen type I?

A

Anything that needs a high tensile strength (tendons and ligaments).

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106
Q

Collagen

A

Colorless but appears white in large amounts
Stains acidophilic
Need Vitamin C to produce
A dozen distinct types - type I is most abundant.

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107
Q

Collagen types

A

Type I: thick and ropelike, high tensile strength. Dermis, bones, tendons, ligaments.
Type II: cartilage/vitreous body
Type III: Fine and spongelike, often found in combination with type I.
Type II-XII: present in a variety of organs

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108
Q

Why does scurvy cause your teeth to fall out?

A

Need Vitamin C to produce collagen. Collagen type one creates the connective tissue that holds your teeth in. Without vitamin c these are some of the first to degrade and the body is unable to resynthesize them.

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109
Q

Reticular Fibers

A

Not visible in H&E prep
Type III collagen, very fine
Form the delicate flexible networks in muscles, nerves, capillaries, adipose tissue, and hemopoietic organs (structural support).

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110
Q

Elastic Fibers

A

Have both elasticity and tensile strength due to covalent cross linking of fibers.
Used in areas that need to expand on a regular basis (arteries, lungs, skin, bladder, etc).
Produced by both fibroblasts/cytes and smooth muscle cells.
Fibrillin and Elastin components.
Unstained: appears yellow.
Lightly acidophilic

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111
Q

Elastin

A

1 of 2 components of Elastic Fibers.

Single strands joined by covalent cross-linking and can expand.

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112
Q

Fibrillin

A

1 of 2 components of Elastic Fibers.

Glycoprotein that covers the elastin core and assists in its formation.

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113
Q

Components of ground substance in connective tissue.

A

Proteoglycans and glycoproteins.

Hydrophilic and form hydrated gels for nutrient migration.

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114
Q

Proteoglycans

A

Glycoprotein + GAGs (glycosaminoglycans)
Look like a pipe cleaner - protein with many GAGs (polysaccharide chains) sticking off of them.
Negatively charged b/c of the GAGs
Hydrophilic

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115
Q

Glycoproteins

A

Structure to which the GAGs are attached.

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116
Q

Loose connective tissue

A

Also called areolar tissue.
High ratio of cells : collagen type I - SOFT
Delicate, less resistant to stress
Supports epithelial tissues, surrounds lymphatic and blood vessels.

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117
Q

Fibronectin

A

Mediates cell binding to CT matrix (adhesion of the epithelial cells to the basement membrane)

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118
Q

Laminin

A

Constituent of the basal lamina (adhesion of the epithelial cells to the basement membrane).

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119
Q

Dense Connective Tissue

A

Low ratio of cells : collagen type I - TOUGH
More resistant to stress
Dermis, organ capsules, tendon sheaths, nerves

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120
Q

Dense Connective Tissue types

A

Irregular
Regular
Elastic

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121
Q

Example of dense irregular connective tissue.

A

Skin

Must hold up to stress in ALL directions.

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122
Q

Example of dense regular connective tissue.

A

Tendons, ligaments
Must hold up to UNIDIRECTIONAL stress.
No branching, very solid and linear on slide.

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123
Q

Example of dense regular elastic tissue.

A

Nuchal ligament

Think of a braid - strong and stretchy. Groups of parallel strands that branch apart.

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124
Q

Unilocular adipose tissue

A

White fat, more common.
Looks like bubble wrap with eccentric nuclei and a large, single fat droplet in each cell.
Store dietary carotenoids (like Vitamin A) giving it a yellowish appearance.
Well vascularized.
SQ tissue, omentum, mesentary, etc.
ATP generation by TCA cycle.
Mechanical function in shock absorption.

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125
Q

Multilocular adipose tissue

A

Brown fat, less common.
Each cell has multiple small fat droplets and a spherical centrally located nucleus. Tons of mitochondria.
Brown or red from density of mitochondria (cytochromes have heme groups). Thermogenesis.
VERY RICHLY vascularized.
Most abundant in babies, small rodents, or hibernating animals.

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126
Q

Functions of cartilage

A

Support for some organs (larynx, trachea, bronchi)
Cover articular surfaces of bones (shock absorption and smooth movement, natural spring)
Growth of long bones

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127
Q

Three types of cartilage? What types of material do they contain?

A

Hyaline (collagen type II)
Elastic (collagen type II and elastic fibers)
Fibrocartilage (collagen type I and type II).

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128
Q

Perichondrium

A

Thick connective tissue on both sides of the hyaline cartilage
Two layers:
Outer is dense irregular CT
Inner is chondrogenic mesenchymal cells

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129
Q

How does hyaline cartilage stain? Why does it stain this way?

A

Lightly basophilic
Lots of negatively charged GAGs on proteoglycans. Allows water to be trapped in cartilage for efficient diffusion of nutrients in avascular tissue.

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130
Q

Chondroblasts

A

Main cartilage producing cells, on the edge of the matrix. Very active.

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131
Q

Chondrocytes

A

A chondroblast that has been surrounded by cartilage matrix and is now less active

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132
Q

What are chondrocytes seen in in slides? Why?

A

Lacunae. Artifact - in the real cell will be pushed to sides but alcohol causes cell shrinkage.

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133
Q

Isogenous cell nests

A

Seen most commonly in hyaline cartilage. Multiple cells in one lacuna, the result of mitotic divisions of a single chondrocyte.
Many in hyaline cartilage, only a few cells in each lacuna in elastic cartilage

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134
Q

What type of connective fiber is in hyaline cartilage matrix?

A

Collagen type II
Cannot see it - thin fibers are submicroscopic and have the same optical density as the ground substance in the matrix. L

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135
Q

Name some of the compounds that form GAGs.

A

hyaluronic acid
chondroitin sulfate
keratin sulfate
heparin sulfate

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136
Q

How does amount of GAGs and amount of proteins in a cell generally relate?

A

Inversely.

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137
Q

In what types of cartilage is perichondrium present?

A

Hyaline and Elastic

138
Q

Name some structures you might find elastic cartilage in

A

External ear

Epiglottis

139
Q

How can you distinguish hyaline cartilage from elastic cartilage?

A

Elastic - less cells in isogenous nests
Elastic - dark staining elastic fibers
Elastic lacunae are surrounded by a basophilic band (territorial matrix
Elastic matrix is less basophilic than hyaline cartilage matrix.

140
Q

What are some similarities of hyaline cartilage and elastic cartilage?

A

Perichondrium

Both have large amounts of collagen type II

141
Q

Compare the amounts of collagens and proteoglycans in the matrix of hyaline and elastic cartilages.

A

Hyaline: more GAGs, less collagen
Elastic: more collagen, less GAGs

142
Q

Territorial matrix

A

Basophilic band surrounding chondrocytes in elastic cartilage

143
Q

Interterritorial matrix

A

Another name for the extracellular matrix of elastic cartilage.

144
Q

Fibrocartilage

A

Alternating basophilic hyaline cartilage bands and acidophilic dense connective tissue bands.
No perichondrium - poorly vascularized, though some vasculature in the CT

145
Q

What are some structures in which you might find fibrocartilage?

A

Immovable joints
Sympheses
Intervertebral discs

146
Q

Interstitial growth of cartilage

A

Growth from within the cartilage matrix, due to chondrocytes in lacunae dividing and secreting new matrix.

147
Q

Appositional growth of cartilage

A

Growth originating from perichondrial mesenchymal cells differentiating into chondroblasts and secreting new matrix. Increases cartilage width.

148
Q

Repair potential of cartilage

A

Hyaline and elastic - easily repaired in young animals due to perichondrium. Harder in older animals as mitotic activity, vascularization and metabolism decreases. Older animals - fibrous connective tissue usually helps repair rather than perichondrium.
Fibrocartilage repair - no perichondrium and limited vascularization, always poor repair potential.

149
Q

Fibrous Articulations

A

Immovable joints of dense fibrous connective tissue that hold bones together in young animals.

150
Q

Synostosis

A

The ossification of dense connective tissue sutures in the flat bones (skull) of young animals

151
Q

Syndesmosis

A

The creation of dense fibrous CT ligaments between bones that does not ossify. When a very small amount of movement is needed, such as in the interosseous membranes of the fore and hind limb.

152
Q

Synchondrosis

A

Two bones joined by hyaline cartilage (such as growth plates).

153
Q

Cartilagenous articulation

A

Immovable or partly movable joints formed by cartilage

154
Q

Symphysis

A

Fibrocartilagenous bond, pad, or disk for limited movement such as in the intervertebral discs or pubic symphysis.

155
Q

Annulus fibrosis

A

Thick outer lamellated fibrocartilagenous region of the intervertebral discs (sl. basophilic in slides)

156
Q

Nuclear pulposus

A

Inner gelatinous substance in intervertebral discs (gray). Full of GAGs to act as a shock absorbing pad in the spinal column.

157
Q

Relaxin

A

Hormone released by some species by pregnant females

Loosens the fibrocartilage of the pelvic symphysis before birth

158
Q

Synovial articulation

A

Moving joints
Three parts: articular cartilage
Joint capsule
Synovial cavity

159
Q

Articular cartilage

A

Superficial zone is compact and densely organized
Deep zone is loosely organized
All hyaline, so collagen type II
Think of a sponge - same action of synovial fluid distribution while compression and decompression occurs during movement
NO perichondrium

160
Q

Joint capsule

A

Encloses the joint
Dense irregular connective tissue on outside
Synovial membrane on inside. Macrophanges and modified fibroblasts.

161
Q

Synovial cavity

A

Contains egg-like consistancy fluid that is primarily hyaluronic acid
Lubricates the joint to protect friction during movement
Provides nutrients for articular cartilage.

162
Q

Synovial villi

A

Folds of the synovial membrane of the joint capsule

Increases the conformity and stability of the joint

163
Q

Functions of bone

A 
Form skeletal support
Protect vital organs
Assists with movement by providing levers for muscle
Houses hematopoietic tissue
Mineral bank for calcium/phosphorus
164
Q

Compact bone

A

Dense areas of bone without cavities. Usually the outer layer of bone and provide structural support.

165
Q

Cancellous bone

A

Spongy bone - network of bone trabeculae. Spaces are fluid or marrow filled.

166
Q

Osteoblasts

A

Sitting on the bone matrix actively making new matrix. Cuboidal or columnar. Basophilic.

167
Q

Osteiod

A

Prebone

Material rich in collagen-I, acidophilic because still poor in minerals.

168
Q

Osteocyte

A

Osteoblast that is now less active and has been surrounded by bone matrix. Participate in the regulation of calcium in metabolic processes. In cells reside in lacunae, one cell per lacuna.

169
Q

Canaliculi

A

Small tunnels between lacunae in bone through which osteoctytes extend membrane processes to contact one another and share nutrients.

170
Q

Osteoclasts

A

Bone resorbing cells
Multinuclear
Formed by the fusion of bone marrow derived cells
Found on the eroding surfaces of bone (resorption lacunae)
Cell membrane has ruffled border, and cell has large number of lysosomal granules and mitochondria
Highest number in growing animals

171
Q

Howship’s lacunae

A

Another name for resorption lacunae. Where osteoclasts have been chewing, an eroding bone surface.

172
Q

Extracellular matrix of bone

A

Collagen Type I
Proteoglycans and glycoproteins (some flexibility)
LOTS of minerals as hydroxyapatite crystals - 65% of dry bone weight
Calcium phosphate
Calcium carbonate

173
Q

Primary bone

A

Immature or woven bone
First to appear in bone development, temporary
Randomly dispersed collagen fibers with low mineral content.

174
Q

Secondary bone

A

Mature or lamellar bone

Not random - complex Haversian systems and periosteum

175
Q

Lamella

A

Layer of matrix between two rows of lacunae in lamellar bone

Up to 20 around each vascular canal

176
Q

Osteons

A

Also called a Haversian system
One central vascular canal (vessels and nerve fibers) and lamellae that consist of osteocytes and canaliculi.
Continually digested and reformed in normal bone remodeling.

177
Q

Periosteum

A

Surrounds the bone. Outer fibrous layer and inner osteogenic layer like perichondrium.

178
Q

Organization of lamellar bones

A 
4 layers: 
Outer circumferential lamellae
Osteons 
Interstiatial lamellae
Inner circumferential lamellae
179
Q

Volkman’s channels

A

Transverse connections that allow the communication of central vascular canals with periosteal surface, marrow cavity, and each other.

180
Q

Organization of Cancellous Bone

A

Trabeculae and interosseous space

181
Q

Trabeculae

A

Thin plates of osseous tissue in spongy bone.

182
Q

Endosteum

A

Layer of osteogeninc tissue covering any spaces with bone marrow. Single layer with some CT and mesenchymal cells.

183
Q

Osteoprogenitor cells

A

Mesenchymal cells with osteogenic potential included in the periosteum inner layer

184
Q

Sharpey’s fibers

A

Also called peforating fibers.

Penetrating collagen fibers that anchor periosteum onto the bone.

185
Q

Two mechanisms of osteogenesis

A 
Intramembranous ossification (straight to bone, named for false "membrane" that osteogenic cells form)
Endochondral ossification (to cartilage and then to bone)
186
Q

General steps of intramembranous ossification

A
  1. Membrane of mesenchymal cells forms
  2. Primary ossification center forms and primary bone laid down by osteoblasts (osteiod)
  3. Mineralization of the osteiod to secondary bone. Some osteoblasts become osteocytes.
  4. Trabecular bone formation - branching from the primary ossification center.
  5. Osteoblasts laid on trabeculae and make them thicker and longer.
  6. Compact bone: spaces between trabeculae fill with osseous tissue.
  7. Cancellous bone: mesenchymal cells trapped between trabeculae become bone marrow.
187
Q

General steps of endochondral ossification

A
  1. Chondroblasts build hyaline cartilage matrix in the shape of future bone.
  2. In center chondrocytes hypertrophy
  3. Chondrocytes calcify their surroundings.
  4. Chondrocytes die due to lack of nutrition.
  5. Blood vessels filled with stem cells invade degenerating cartilage.
  6. Osteoprogenitor cells differentiate to osteoblasts.
  7. Osteoblasts ossify old cartilage matrix.
  8. Ossification spreads towards the ends of the long bones.
  9. Osteoclasts come in to digest bone at primary ossification center. Mesenchymal cells in blood vessels form marrow in new medullary cavity.
188
Q

Bone collar

A

Forms around the primary ossification center on the diaphysis. From the periosteum forming as blood vessels invade degenerating cartilage.

189
Q

Periosteal bud

A

Blood vessels from the periosteum along with invading stem cells

190
Q

When does the primary ossification center first develop?

A

Technically when osteoprogenitor cells carried in by blood vessels start to differentiate to osteoblasts and laying down bone matrix.

191
Q

Medullary cavity

A

Empty area in bone formed by osteoclasts and filled by marrow.

192
Q

Diaphysis

A

Long part of the long bone

193
Q

Secondary ossification center

A

In center of epiphysis at the ends of long bones
Appear around birth in most species
Same process 2-9 as in the diaphysis
Hyaline cartilage cap will remain as articular cartilage

194
Q

Two mechanisms of bone growth

A

Interstitial growth

Appositional growth

195
Q

What are the zones seen in interstitial growth?

A

Zone of resting cartilage - normal hyaline cartilage
Zone of proliferation - chondrocytes proliferate quickly and look like stacks of coins
Zone of hypertrophy - Large lacunae with cells still inside of them
Zone of calcification - Large empty lacunae
Zone of ossification - undifferentiated cells start depositing on the bone matrix.

196
Q

What is responsible for the growth in width of the bones?

A

Appositional growth

Addition of new matrix from surface differentiation of the periosteum.

197
Q

Metaphysis

A

Weakest part of the growing bone because it is degenerated without much bone yet.

198
Q

What are two other names for the cell body of a neuron?

A

Soma or perikaryon

199
Q

Dendrites

A

Receive signal from potentially thousands of cells

200
Q

Axon

A

Single tube-like structure for signals to pass through the neuron. Thicker and longer than dendrites.

201
Q

Myelin sheath

A

Fatty white substance around the axon. Saves energy and speeds up the signal.

202
Q

Synapse

A

Area between the axon terminal and the next neuron’s dendrites.

203
Q

Telodendria

A

Fingerlike processes of the axon terminal to send signals.

204
Q

Bipolar neurons

A

Two processes coming from opposite ends of the cell body, one which has dendrites and the other being an axon terminal. Relatively infrequent, receptors of the visual and auditory systems. Always terminate in the CNS.

205
Q

Pseudounipolar neurons

A

CENTRAL nuclei
Single process from the cell body which then differentiates into two branches, one for dendrites and one for axon terminal. Sensory - axons in the CNS and dendrites in organs or tissue.

206
Q

Multipolar neurons

A

ECCENTRIC nuclei
Most common. Multiple dendrites and one axon leave the cell body. Both motor and integrative. Dendrites in either CNS or autonomic ganglion.

207
Q

Sensory neurons are also called?

A

Afferent neurons. Receive input from periphery and translate to the CNS.

208
Q

Motor neurons are also called?

A

Efferent neurons. Send signals from the CNS to effectors.

209
Q

Interneurons

A

Conduct impulses between neurons. Allow fro complex functional circuits and networks.

210
Q

What are the prominent features of the neuronal soma?

A

Nucleus with a prominent nucleolus. Euchromatic.

Cytoplasmic basophilic patches = Nissl substance from free polyribosomes and abundant RER.

211
Q

How can an axon be differentiated from a dendrite microscopically?

A

Dendrites have Nissl substance and usually prominent Golgi bodies
Axons do not, and are usually larger.

212
Q

Axon hillock

A

Part of the cell body that the axon arises from.

213
Q

Axolemma

A

Axon plasma membrane

214
Q

Axoplasm

A

Axon cytoplasm

Neurotubules and neurofilaments, some mitochondria and smooth ER

215
Q

Peripheral Nervous Tissue

A

Anything external to the brain and spinal cord

216
Q

Schwann cell

A

Myelination mechanism of the PNS. Formed by wrapping the membrane (lipoprotein matrix) around the axon many many times. Can be seen with osmotic (black) stain that works on fat. Can be 100s per axon.

217
Q

Myelinated Nerve Fiber

A

Axon and myelin sheath.

218
Q

Node of Ranvier

A

Gaps along the axon that are not myelinated.

219
Q

How does myelination increase signal speed?

A

Using saltatory conduction. Creates areas of positive charge under the myelin and negative charge at the nodes that signal can “jump” across rather than having to depolarize every section of membrane.

220
Q

How does myelination conserve energy?

A

Signal is transmitted by depolarization of the membrane using Na+/K+ pumps, both of which require ATP. Less surface area exposed to the environment = less pumps requiring energy.

221
Q

Unmyelinated nerve fiber

A

Usually for small diameter axons
Multiple will held in the invaginations of a Schwann cell
Schwann cell still can conserve energy but does not speed the signal

222
Q

What are some diseases caused by demyelination?

A

Schizophrenia, bipolar disorders, MS.

223
Q

What are the three layers that organize the tissue in the nerves of the PNS?

A

Epineurium, Perineurium, and Endoneurium

224
Q

Epineurium

A

Outer layer of the nerves, loose connective tissue of mostly collagen and elastic fibers.
Holds multiple nerve bundles together.
contains some fibroblasts/cytes, adipose cells, mast cells and macrophages.

225
Q

Perineurium

A

Dark acidophilic band.
Holds a number of neurons together into a bundle.
Dense irregular connective tissue

226
Q

Endoneurium

A

Delicate thin tissue around each neuron.

Made of reticular (collagen type III) fibers synthesized by Schwann cells.

227
Q

Affectors

A

Sensory organs, always connected to the dendrites of pseudounipolar neurons.
Photo-, mechano-, thermo-, chemo-, or pain receptors.

228
Q

Pacinian corpuscle

A

Huge affector deep in the dermis of the skin.
Also in joint capsules and some serous membranes.
Looks like an onion.
Receptor for pressure, vibration, and tension.

229
Q

Effectors

A

Muscles or glands with the ability to respond to signals from the CNS
Terminals of multipolar neurons.

230
Q

Neuromuscular junctions

A

Regions in muscle cell where telodendria end, where neurotransmitters from multipolar neurons can cause contraction.

231
Q

Ganglia

A

Aggregates of neuronal cell bodies outside of the CNS.

Serve as relay stations for nerve pulses.

232
Q

Dorsal root ganglia

A

Sensory/afferent neurons

DO NOT CONTAIN SYNAPSES

233
Q

Where are the two most prominent ganglia?

A 
Cranial ganglia (for cranial nerves)
Spinal ganglia (for spinal nerves)
234
Q

Satellite cells of ganglia

A

Smaller supportive cells surrounding the cell bodies for electrical insulation and nutrient exchange.

235
Q

Lateral root ganglia

A

Efferent/Motor AUTONOMIC ganglia. Full of synapses between presynaptic (preganglionic) and postsynaptic (postganglionic) neurons.

236
Q

Two classes of the autonomic nervous system

A

Sympathetic (fight or flight)
or
Parasympathetic (rest and digest)

237
Q

How can a efferent ganglia be distinguished from an afferent ganglia?

A

Afferent: Central nuclei in cell bodies. No dendrites.
Efferent: Eccentric nuclei in cell bodies. Cell bodies have many processes.

238
Q

What are some similarities between efferent and afferent ganglia?

A

Both have satellite cells.
Both are basophilic.
Both are surrounded by a dense, fibrous CT capsule

239
Q

What determines the regeneration properties of a neuron?

A

Type of myelinating cell - Schwann cells only, so only peripheral nerves can be repaired.
Distance of damage from cell body - closer is worse.

240
Q

What are the general steps of regeneration of a neuron?

A
  1. Macrophages digest distal axon and myelin sheath distal to damage. Nucleus becomes eccentric and Nissl substance disperses during this process.
  2. Macrophages stimulate Schwann cell proliferation distally.
  3. Schwann cells stimulate growth of the nerve, which will have many axonal sprouts. Nucleus returns centrally.
  4. Once they reach the target - extra axonal sprouts and schwann cells are removed.
241
Q

Chromatolysis

A

Loss of color. Seen in the initial stages of nerve repair as Nissl substance disperses out of the cell body.

242
Q

Oligodendrocytes

A

Myelinating cells of the CNS. One cell can mylinate many axons.
Same nodes of ranvier exist

243
Q

Neuroma

A

The source of spontaneous limb pain in amputees. Caused by nerve fibers trying to regenerate and ending up in a swollen mass.

244
Q

Gray matter of the CNS

A

Processing centers.

Contain cell bodies and glial cells.

245
Q

White matter of the CNS

A

Communication centers

Contains myelinated axons

246
Q

What are glial cells?

A

Supportive cells of the CNS, outnumber the neuron cells 10 to 1.

247
Q

What are the types of glial cells?

A

Oligodendrocytes
Astrocytes
Microglia

248
Q

Astocytes

A

Star shaped cells with radiating processes that anchor neurons to capillaries.
Will proliferate to form scar tissue in the CNS if it is damaged.

249
Q

Microglia

A

Phagocytic cells to eliminated any damaged cells.
Derved from monocytes
Small and elongated cells with short processes

250
Q

Ventral horn of the CNS

A

Cell bodies of somatic efferent neurons.

251
Q

Gray matter divisions in the spinal cord

A

Dorsal horn: Afferent neurons
Lateral horn: AUTONOMIC efferent neurons
Ventral horn: SOMATIC efferent neurons

252
Q

White matter divisions in the spinal cord

A

Dorsal funiculis
Lateral funiculis
Ventral funiculis

253
Q

What changes between the cerebellum and the spinal cord in terms of organization of tissue?

A

Spinal cord: white matter outside of gray matter.

Cerebellum: Gray matter outside of white matter.

254
Q

Gray matter of the cerebellum is also called? What is it’s function?

A

The cerebellar cortex

Integration of sensor perception and coordination of skeletal muscle (but no initiation of movement).

255
Q

Three layers of the cerebellar cortex? What are their purposes?

A

Molecular layer: Sparse, mostly the dendrites of purkinje cells. Basophilic and contains Nissl substance.
Purkinje layer: Single layer of large cell bodies and glial cells. Interneurons that fine tune muscle movement and cooridinate balance.
Granular layer: Small interneurons, compactly organized.

256
Q

Skeletal muscle

A

Striated. Multinucleated.
Somatic nervous system controls.
Most but not all connected to skeleton.

257
Q

Cardiac muscle

A

Striated. Two nuclei in cells.

Autonomic nervous system controls.

258
Q

Smooth muscle

A

Arteries, lymph vessels, digestive system, reproductive tract.
Autonomic nervous system controls.

259
Q

Myotubes

A

Embryonic structures that form into one long multinucleated muscle cell before birth.

260
Q

Layers of tissue that organize muscle

A

Perimysium
Endomysium
Epimysium

261
Q

Perimysium

A

Around one muscle fascicle
Distinct acidophilic band
Binds vessels
Collagen type I

262
Q

Endomysium

A

Delicate tissue around multiple muscle fibers
Collagen type III
Also contains vessels, lymph, and nerves

263
Q

Epimysium

A

Dense connective tissue
Around many muscle fascicles
Type I collagen
Also acidophilic

264
Q

What are the functions of connective tissue in muscle?

A

Bundling = greater transmission of force to the bone for movement
Provides pathways fro nerves and vessels.

265
Q

Myofibrils

A

Contractile structures inside muscle cells

266
Q

Sarcoplasmic reticulum

A

Ca2+ filled sac wrapping around the myofibrils.

267
Q

Sarcomere

A

Short structural unit of a myofibril.

268
Q

Z band

A

Junctions between sarcomeres

Surrounded by the I band

269
Q

A band

A

Anisotropic (unequal distribution of atoms)

Dark band formed by thick and thin filaments.

270
Q

I band

A

Isotropic (even distribution of atoms)
Light band formed by thin filaments exclusively
The part of the sarcomere that shrinks during contraction.

271
Q

Thick filaments

A 
Myosin II molecules
The molecular motors that generate the force for contraction
Two sites:
1. Actin binding site
2. ATPase site
272
Q

Thin filaments

A

Actin bands

Covered in troponin and tropomyosin

273
Q

Acetylcholine

A

Chemical released at the neuromuscular junction causing the muscle membrane to depolarize by opening gated ion channels.

274
Q

Myesthenia gravis

A

Autoimmune production of antibodies to acetylcholine receptors so that no muscle contraction is produced.

275
Q

How many muscle cells have a neuromuscular junction?

A

All of them!!

Motor nerve breaks into many telodendria, each of which innervates an individual muscle cell.

276
Q

T-tubules

A

Fingers of the plasma membrane of the muscle cell down into the sarcoplasmic reticulum. Spreads depolarization of the membrane so that the whole cell will react.

277
Q

What are the general steps of muscle contraction?

A
  1. Acetylcholine changes the membrane potential of the cell.
  2. Change in membrane potential travels to sarcoplasmic reticulum via T-tubules.
  3. Sarcoplasmic reticulum releases calcium.
  4. Calcium binds to troponin
  5. Troponin+Ca pulls tropomyosin away from the myosin binding sites on the actin filaments.
  6. Myosin heads with ATP constitutively attached bind actin and then hydrolyze ATP, causing a conformational change in the myosin head.
  7. Conformational change pulls the thin filaments over the thick filaments.
  8. When muscle relaxes calcium is pumped back into the SR.
278
Q

Muscle spindles

A

Sensory organ to sense and prevent stretching of the muscle.

279
Q

Intrafusal fibers

A

Sensory fibers (have a sensory nerve), surrounded by connective tissue

280
Q

Extrafusal fibers

A

Normal muscle fibers outside of the muscle spindle.

281
Q

What is the mechanism of the muscle spindles?

A
  1. Stretch muscle
  2. Sensory nerve in intrafusal fiber activated
  3. Signal to spinal cord
  4. Reflex arc (interneuron) in spinal cord causes muscle to contract
  5. Signal sent up spinal cord to the brain so it knows what happened.
282
Q

What are the three layers of the heart?

A

Endocardium - continuous with endothelium on inside
Myocardium - central cardiac muscle
Epicardium - continuous with mesothelium on outside

283
Q

Why are cardiac muscle cells branched?

A

To cause the heart to beat as a functional system (all at once) by forming inter-connections between cells.

284
Q

Intercalculated discs

A

Attachments between cardiac cells for mechanical and electrical communication through gap junctions and macula adherents (belt desmosomes).

285
Q

Purkinje fibers

A

Pale thin fibers that conduct impulses from the atrioventricular nerve bundle of the SA node over the base of the heart to make sure it beats as one unit.

286
Q

Cardiac cell halo

A

Artifact of slide preparation of cardiac cells around the nucleus, but very distinctive.

287
Q

How do you distinguish a smooth muscle cell?

A

No striation

Single nucleus, often corkscrew shaped due to contractions

288
Q

What is the purpose of smooth muscle?

A

Slow, long lasting contractions

289
Q

Smooth muscle contraction

A

Myosin heads do not constitutively bind ATP
When Ca2+ released in the cell, Ca2+ binds calmodulin
Calmodulin interacts with myosin light chain kinase and phosphorylates myosin
Contractile action can then begin.

290
Q

Peristalsis

A

Smooth muscle movement around a tube
Lengthwise and circular fibers will cause both shortening and contraction of the tube
Helps push food through the GI tract.

291
Q

What tissue is the epidermis?

A

Keratinized stratified squamous epithelium

292
Q

What tissue is the dermis?

A

Dense irregular connective tissue

293
Q

What tissue is the hypodermis?

A

Loose connective tissue and adipose tissue

294
Q

Functions of the integument

A

Protects from:
desiccation, invasion by microorganisms, UV light, chemical and mechanical insults
Sensation for touch, pressure, pain and temperature
Storage of energy in fat
Synthesis of Vitamin D

295
Q

Keratinocytes

A

90% of the epidermal cells

296
Q

Nonkeratinocytes

A 
10% of the epidermal cells
3 types:
Melanocytes
Merkel cells
Langerhans cells
297
Q

What are the layers of the epidermis? How can they be identified?

A

Stratum basale/germinativum: basal layer of cuboidal-columnar cells where mitosis occurs
Stratum spinosum: Spiny due to protein filaments through spot desmosomes.
Stratum granulosum: Production of keratin in basophilic granules begins. Up to 8 layers in thick skin.
Stratum lucidum: Only in non-haired heavily used regions. Glassy dead (enucleated) cells. Barrier to water.
Stratum corneum: Outermost layer, dead, flattened, keratinized cells.

298
Q

Melanocytes

A

Found in basal layer of epidermis. Send processes or melanosomes into spinal spinosum.
Synthesize melanin into melanosomes. These are pinched off and carried into stratum spinosum cells.
Melanin randomly dispersed in the cytosol or in a cap over the nucleus.

299
Q

Merkel cells

A

Mechanoreceptors for light touch

In small numbers in the basal layer of the epidermis

300
Q

Langerhans cells

A

Protection from microorganisms
In the upper stratum spinosum
Antigenic stimulation causes them to process and present antigens to T-lymphocytes

301
Q

What is a wart?

A

Over production of keratin in the stratum corneum.

302
Q

Tyrosinease

A

Convert white tyrosine to melanin in the melanocyte.

303
Q

What causes freckles?

A

Overproduction by one melanocyte.

304
Q

What causes moles?

A

Cluster of melanocytes.

305
Q

How do Langerhans cells cause HIV?

A

Many in the vaginal mucosa and foreskin. Starts the spread of the retrovirus to the T cells.

306
Q

Is the epidermis thicker or thinner in haired regions?

A

Thinner.

307
Q

Rete ridges

A

Fingerlike projections of the epidermis into the dermis
Protects epidermis from shear forces on the skin
Prominent in non-haired regions

308
Q

Dermal papillae

A

Dermal projections into the epidermis

Contains blood vessels to nourish the epidermis

309
Q

What is the function of the dermis?

A

Nutrient diffusion to the epidermis. Ground substance in matrix allows more efficient diffusion.

310
Q

What is the function of the hypodermis?

A 
Anchors dermis to underlying muscle and bone. 
Allows skin flexibility and movement over underlying structures. 
Stores energy (fat)
311
Q

Panniculus adiposus

A

Pad or cushion of adipose tissue in the hypodermis.

312
Q

Functions of hair

A 
Insulation
Protection from sun and rain
Axillary - large area for sweat evaporation
Vibrissae: sensory tactile hairs
Keep out dust particles
BEAUTIFICATION!!!!!!!
313
Q

Name some epidermal modifications

A

Hair
Feathers
Hooves
Nails

314
Q

Main stuctures of the hair

A

Follicle: Anchor and growth
Shaft: Dead keratinized tissue

315
Q

Three main layers of the hair shaft? How to recognize them?

A

Medulla: Only primary hairs have. Loosely organized round cells, central.
Cortex: Middle - compacted and elongated cells housing the pigment.
Cuticle: Outer layer. Flat keratinized cells overlap like shingles. Out of the skin when exposed to air.

316
Q

What causes the colors of hair?

A

Phaeomelanin: Tan, yellow, red or light brown.
Eumelanin: Black, dark brown
Lack of melanin: White hair

317
Q

Organization of the hair follicles and how to recognize the components

A

Hair bulb: deepest part of follicle
Dermal papilla: Projection of dermis into the bulb.
Germinal matrix cells: Covers dermal papilla, constantly dividing.
External root sheath: Glassy basement membrane separating the bulb from dermis.
Internal root sheath: Layer surrounding the hair root, inside the external.

318
Q

Simple hair follicle

A

One primary hair emerges. Also associated with sebaceous glands, sweat glands, and arrector pili muscles.

319
Q

Compound hair follicle

A

One primary and several secondary hairs emerges. Also associated with sebaceous glands, sweat glands, and arrector pili muscles.

320
Q

What are the three stages of hair growth?

A

Anagen
Catagen
Telogen

321
Q

What is baldness caused by?

A

Hormonal changes that cause hair follicles to atrophy without the formation of new follicles. Death of follicles.

322
Q

What is baldness due to chemotherapy caused by?

A

Drugs targeting mitotically active cells.

323
Q

Anagen Phase

A

New hair pushes out the old hair, follicle descends to the dermis. Active cell division and keratinization. Length of this period will determine the length of the hair.

324
Q

Catagen Phase

A

Cessation of mitotic activity. Entire hair bulb cornifies. Base of the hair follicle moves upwards towards sebaceous gland. New follicle forms deep to the old one.

325
Q

Telogen Phase

A

Resting phase.

326
Q

Arrector pili muscles

A

Smooth muscle
Appears more basophilic than surrounding collagen
Innervated by sympathetic nervous tissue
Contraction causes hair to stand up - insulation or aggression
Attach to connective tissue sheath and slant
Long cigar shaped nucleus

327
Q

Sinus Hair follicles

A

3x deeper into dermis
Has all elements + blood sinus and internal and external connective sheaths
Sensory nerve attaches to blood sinus. Any movement of the hair causes amplification in the sinus.

328
Q

Sebaceous glands

A

Holocrine
Produce sebum
Lubricates hair to prevent heat and water loss
Also antimicrobial
Duct opens to upper third of hair follicle

329
Q

Apocrine sweat glands

A

Open to hair duct just superficial to sebaceous gland

Milky secretion with fat

330
Q

Merocrine sweat glands

A

Open directly to skin surface
Mostly water
Footpads of dogs/cats and noses of ruminants/swine

331
Q

Where are the apo/mero sweat glands on humans? Where are they on animals?

A

Apocrine in the axillary region of humans and the haired region of animals.
Merocrine on the rest of humans and the footpads of animals.

332
Q

Tear film of eyes and what glands form them

A

Oily layer: Tarsal glands
Water layer: Lacrimal glands
Mucous layer: Goblet cells

333
Q

Function of the oily layer of the tear film

A

Prevents the evaporation of the water layer
Prevents tear spillage
Makes eyes airtight when closed

334
Q

Orbicularis

A

Striated muscle of the eyelid

335
Q

Function of the mucous layer of the tear film

A

GAGs even out the water layer on the surface of the eye.

336
Q

Anal glands

A

Modified sweat glands
Glycoprotein and lipid rich - coats the stool as it passes
Ducts open into the columnar and intermediate zones of anal canal

337
Q

Zones of the anal canal

A

Columnar (inner)
Intermediate
Cutaneous (outer)

338
Q

How can you tell the anal canal from the rectum

A

ABRUPT change in epithelium from columnar epithelium to stratified kerainized squamous epithelium

339
Q

Circumanal glands

A

Also called perianal glands
Modified sebaceous glands (foamy appearance)
Open into cutaneous zone of the anal canal
Deeper cells are hepatoid (ductless, look like cuboidal liver cells)

340
Q

Anal sac

A

Paired invaginations of the mucocutaneous zone, each with own duct
Lined with stratified squamous keratinized epithelium
Will accumulate fluid with soft stools - rely on the anal sphincter and hard stools to be normally expressed

341
Q

Perisaccular glands

A

Modified sweat glands that open into the anal sac

Malodorous secretions for identification of stools.

Histology (Fall) (3 decks)

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