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D1 Histology > Written Exam 2 > Flashcards

Written Exam 2 Flashcards

1
Q

What does the skin do?

A
  • Protective (barrier)
    • Minimize water loss
    • Prevent entry of pathogens
    • UV radiation
    • Physical forces
  • Sensory
  • Body temp regulation
  • Produce vitamin D
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2
Q

What layer of the skin are epithelial cells found?

A

Epidermis

(epi = epi)

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3
Q

Name and describe the layers that make up the skin

A
  1. Epidermis (Epi = on top of)
  2. Dermis
    1. CT under the epidermis
  3. Hypodermis (hypo = below)
    1. CT under the dermis
      1. Lots of adipose tissue!
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4
Q

Explain the difference between thick skin and thin skin and where each are found

A
  • Thick skin:
    • Found in palm of hands and bottom of feet
      • Lots of keratinized epithelium
    • thick epidermis
      • Varies a lot (differentiation point between thickness of skin)
    • smaller dermis
  • Thin skin:
    • Found everywhere on skin but palms of hands and bottom of feet
    • Skinnier epidermis
      • Not as much keratinized epithelium
    • Thicker dermis
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5
Q

What is skin cancer and why can there be several types?

A

Cancer = uncontrolled cell growth

How can there be several types?

There is more than one type of cell in the skin

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6
Q

What are the cells found in the epidermis, what type of cancer can be found in each cell type and where they are located?

A
  • Basal Cells = Basal cell carcinoma
  • Keratinocytes = squamous cell carconoma (flat c)
  • Squamous cells = squamous cell carconoma
  • Melanocytes = melanoma (pigmented moles)
    • In basal layer
  • Merkel cells = Merkel cell carcinoma
    • In basal layer
  • Langerhans cells = Immune cells in epidermis
    • Dendritic cells (stratum spinosum)
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7
Q

What is the function of the tactile cells?

A

Tactile (Merkel) cells

  • located in basal layer throughout. Sensory nerve endings attach to these cells
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8
Q

What is the following layer of the epidermis called and what are the distinct characteristics?

A

Stratum Basale

(layer base)

  • One cell layer thick
  • cuboidal or columnar cells
  • contain demidesmosomes to attach to CT under
  • mitotic cells - stem cells, production of new cells
  • contain desmosomes to attach to each other
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9
Q

What is the following layer of the epidermis called and what are the distinct characteristics?

(black arrow)

A

Stratum spinosum

  • No hemidesmosomes (does not attach to CT)
  • Has desmosomes (attach to each other)
  • Some mitotic cells
  • Thicker in thick skin than thin
  • Active cells => makes protein (keratin)
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10
Q

Explain the function/process of keratinocytes and where they are located in the epidermis

A

Keratinocytes in the stratum spinosum

>>>>>

producing keratin

>>>>>

Makes up the intermediate filaments (made of keratin) in the epithelial cells of the skin

(tonofibrils) = special name

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11
Q

Remember: intermediate filaments are involved in intracellular adhesion

Which type of junction involves the intermediate filament?

A

Desmosomes

= integrins

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12
Q

Explain the components in the following EM slide

A

Keratinocytes in the stratum spinosum

  • Tonofibrils of keratin = dark lines
    • intermediate filaments
  • Cytoplsamic extensions
  • Desmosomes
    • electron dense
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13
Q

Describe the following slide

A

Keratinocytes in the stratum spinosum

(looks like a spine = prickly)

  • What would you say about the nuclei?
    • Euchromatic = active
      • DNA dispersed
  • Looks prickly or spiny = cytoplasmic extension
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14
Q

What is the following layer of the epidermis called and what are the distinct characteristics?

(black arrow)

A

Stratum granulosum

  • squamous shape
  • Only 3 to 5 layers thick
  • Cells develop a lipid envelope (water resistance)
  • Cytoplasm has Basophilic masses
    • Hemotoxylin staining
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15
Q

Explain a summary of the differentiation of cells in the stratum granulosum

A
  • Cells contain many keratohyaline granules
    • Contain several proteins, including profilaggrin
    • Granules stain w/hematoxylin = dark color
  • Cells also contin many lamellar grandules
    • contain several substances, including lipids
    • The nucleus and other organelles degrade and the cells begin to die in this layer
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16
Q

Explain a summary of the keratinization of cells in the stratum granulosum

A
  • Proflaggrin is proteolysed into multiple filagrin monmers.
    • Free filaggrin binds to keratin intermediate filaments, causing aggregation into macrofibrils
      • intermediate filaments aligned in tightly packed parallel arrays
  • Lipids and other substances are secreted from lamellar granules
    • forming a lipid barrier encircling the cell
  • Lipid + filaggrin + keratin matrix = important skin barrier
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17
Q

Explain the end result of keratinization in the stratum granulosum layer of the epithelium

A

End result of keratinization -> cornified cell

Compressed keratin + filaggrin

  • Contains lipid envelope:
    • Prevents abrasion
    • Prevents desication
    • Protects form infection
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18
Q

What is the following layer of the epidermis called and what are the distinct characteristics?

(black arrow)

A

Stratum lucidum

  • light layer above the stratum granulosum
  • ONLY in thick skin
  • Cells that lost their organelles
  • Contain desmosomes = cells still attached to each other
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19
Q

What are the following structures in this slide?

A

stratum lucidium = light layer

stratum granulosum = dark layer

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20
Q

What is the following layer of the epidermis called and what are the distinct characteristics?

(black arrow)

A

Stratum corneum

  • Very thick in thick skin and very thin in thin skin

Non nucleated, keratinized cells called squames or cornified cells

  • Contains loose desmosomes
  • Cells at surface begin to sluff off as the desmosomes break down
    • Keratin dust
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21
Q

Where are melanocytes located?

What is the function of melanocytes?

A
  • Melanocytes = dispersed throughout the stratum basale
  • Melanin is packaged in small special vesicles called = melanosomes
  • Melanocytes have cytoplasmic extensions or dendrites. The melanosomes mature and move to the tip of the dentrite
  • The tip of the dendrites with the melanosomes is engulfed by keratinocytes and the melanosomes move towards the nucleus
    • Produce melanin and transfer it to keratinocytes
    • Tip of the melanocyte gets moved/bit off and goes to the keratinocyte
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22
Q

What is the following cell?

A

Melanocyte

Can tell it is a melanocyte because of the hollow (clear area)

  • Error from the tissue processing

Melanin capping the nucleus of a keratinocyte

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23
Q

Why does melanin accumulate in this supranuclear cap?

A

Protects DNA from UV radiation

  • All skin color has the SAME DENSITY of melanocytes, however there may be LESS MELANIN IN KERATINOCYTES
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24
Q

What are these brown stained cells?

A

Langerhans Cells

- Immune cells

Type of dendritic cells

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25
Q

Explain how langerhan cells, or dendritic cells, are involved in immune response

A

Immune cells

Phagocytize antigen

>>>>>

move to the lymph node

>>>>>>

Present the antigen to lymphocytes

START THE IMMUNE RESPONSE

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26
Q

DEFECTS IN CUTANEOUS BARRIER FUNCTION CAN PREDISPOSE AN INDIVIDUAL TO SKIN DISEASES, SUCH AS ATOPIC DERMATITIS. A GENETIC DEFECT CAUSING THE LOSS OF WHICH OF THE FOLLOWING WOULD MOST LIKELY CONTRIBUTE TO THIS?

A

Filaggrin

rash development and holes in skin

Because it deals with keratinization and is the cutaneous barrier

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27
Q

What features can be found in the dermis of the skin?

A

Blood vessels

Connective tissue

Hair

Nerves

Sebaceous and sweat glands

Sensory receptors

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28
Q

What do you notice about the interface between the epidermis and dermis?

What are their functions?

A

Dermal Papilla = bumps up from the dermis

Epidermal Ridge = Pokes down from the epidermis

Strength - ie reinforce the dermal-epidermal junction

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29
Q

What are the two following layers in the thin skin sample

A
  • Papillary Layer = dermal papilla - up from dermis
    • Fine collagen, elastic fibers with
      • MORE CELLS
    • Loose CT
  • Reticular layer = network of CT
    • Course collagen, elastic fibers
      • LESS CELLS
    • Dense Irregular CT
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30
Q

What type of collagen is found in the dermis?

A

Type I = lots in the reticular layer

Type III = Reticular fibers. Lots in the papillary layer (dermis)

Type IV = In the basal lamina/basement membrane (papillary layer = dermis)

Type VII = Anchoring collagen (papillary layer)

Note: Basement membrane is considered part of the dermis

basal lamina = basement membrane = dermis

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31
Q

What are the two types of sensory receptors in the skin?

A

Nerve Endings

  • Not encapsulated
  • Encapsulated (mylinated)
    • Collagen and modified schwann cells
      • Schwann cells = form myelin sheath
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32
Q

What is the function of free nerve endings and where are they located?

A

Free nerve endings = sensory neurons

Location = epidermis

Function: Sense pain, temperature, itching, light pressure (touch)

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33
Q

What is the function of Merkel cells and where are they located?

A

Location: Scattered throughout basal layer of epidermis which is connected to the

merkel (tactile) disc

Function: Sense light touch

Non-encapsulated = simple nerve ending

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34
Q

What is the function of root hair plexus nerves? Where are they located?

A

Location: Nerves wrapped around the plexus of a hair

Function: sense hair movement

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35
Q

What are the two types of corpuscles that are found in the dermis and where in the dermis are they located?

A
  • Meissner corpuscle
    • Sits in the dermal papilla
  • Pacinian Corpuscle
    • Deeper in the dermis
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36
Q

What is the following feature?

A

Meissner Corpuscle

  • Extremely difficult to see and will be super lucky to find one
  • Sits in the dermal papilla
  • Unmylinated nerve ending
  • Surrounded by modified schwann cells and capsule
  • Function: feel shapes, detail
  • Location: Hands, fingers, lips, tongue and sole of the feet
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37
Q

What is the following feature and explain function, location, details

A

Pacinian corpuscle

Very easy to see in a section of your skin

  • Location: Deeper in the dermis
  • Axon w/modified schwann cells
  • Function: Course touch, pressure and vibrations
  • Not too many but due to large capusle they can sense when capsule is moved
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38
Q

A 34 year ld female is stung by a bee. She develops urticaria (hives) and pruritus (itchiness). What is going on in the dermis of the skin to cause this reaction?

A

Mast cells degranulate and release histamine

mast cells are in the skin!!

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39
Q

What causes itching?

A

Free nerve endings

  1. Histamine release
  2. Histamine binds to H1 receptor
  3. Itching feeling
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40
Q

Explain the anatomy around the hair follicle

A
  • Arrector pili muscle = smooth muscle
    • Body temp. regulation
    • Sympathetic nervous system (involuntary)
  • Outside in:
    • Invagination of the epidermis
    • External rooth sheath
      • Sheaths the root of the hair, not involved in the production of the hair
    • Matrix
      • Under the sheath
    • Hair pulp, Dermal papilla
      • nutrient/blood supply to matrix
      • CT with blood vellels
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41
Q

Explain the anatomy of an oblique section of a hair follicle

A

Oblique section of a hair follicle

  • Cells move up and are keratinized to form the hair root and shaft
  • Matrix
    • Dividing epithelial cells and melanocytes
      • Because hair has color to it
      • Epithelial tissue = avascular, cells need nutrients from the dermal papilla
  • Dermal papilla
    • CT with blood vessels
      • Supplies blood to the hair (to matrix)
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42
Q

Explain the anatomy of a cross section of a hair follicle

A

**Do not see matrix here

  • Connective tissue sheath
  • Glassy membrane
    • Like the basement membrane
  • External root sheath
    • Invaginated epidermal cells
  • Internal root sheath
    • Comes from the matrix with a softer keratin
      • Not from head or skin
  • Hair (keratinized cells)
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43
Q

What is the following feature and where are they located?

Why does the feature not stain?

A

Sebaceous gland

  • These are epithelial cells that make up the gland
  • Produce: sebum
  • Lined with undifferentiated epithelial cell differentiate into sebocytes
  • Then lined with Basal lamina
  • Outside layer: Connective tissue capusle surrounds the gland
  • Location: Face, forehead, scalp

Does not stain: Cytoplasm filled with fat droplets

Sebum = waxy mix of cholesterol and fat that coat the skin and hair

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44
Q

How is sebum secrted into the hair follicle with sebaceous gland?

A

Holocrine secretion

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45
Q

What type of glands are sebaceous glands?

A

Branched acini

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46
Q

Name and the following features in the image and where they are located

A
  • Duct opens to surface
  • Eccrine sweat gland (All over the body)
  • Duct opens to hair follicle
  • Apocrine sweat gland (axillary and perineal regions)
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47
Q

What is the following structure?

What are the following features in the structure

A

Eccrine sweat gland

  • Small lumen
  • Cuboidal epithelium with underlying myoepithelial cells
  • Duct
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48
Q

What is the following structure?

What features make up the structure?

A

Apocrine sweat gland

  • Large lumen
  • Cuboidal epithelium with underlying myoepithelial cells
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49
Q

what type of tissue is cartilage?

A

Connective tissue

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50
Q

What are the types of cartilage and where are they found?

A
  1. Hyaline (blue)
    1. Articular cartilage (ie. Joints)
  2. Fibrocartilage (red)
    1. Vertebral disks
  3. Elastic (purple)
    1. Ear
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51
Q

What is the following features in the image?

A
  • Perichondrium
    • Peri = around
    • chondro = cartilage
  • Hyaline cartilage
    • Dark spots inside cartilage = chondrocytes
      • cells of cartilage
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52
Q

What is the following picture of? name and describe the features of the tissue

A

Hyaline cartilage

  • Very glassy
  • Lots of extracellular matrix
  • Contains lots of condracytes
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53
Q

Does the extracellular matrix in the perichondrium look the same as the ECM in hyaline cartilage?

Describe the tissues in the cartilage layers

A

NO

  • Perichondrium:
    • Dense CT
    • Type I collagen
  • Hyaline cartilage:
    • Type II collagen fibrils
    • Lots of ground substance
    • forms a gel
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54
Q

Why does the extracellular matrix in hyaline cartilage appear more purple?

A

Blue + pink = purple

  • Aggrecan = proteoglycans
    • Protein + GAG (lots of negatively charged sulfates)
      • Proteoglycans!!! Lots of branching (purple in color)
  • Hyaluronic acid
    • Glycosomino glycan in the ground substance (GAG)
    • Blue color
  • Type II collagen
    • Fibers = more pink
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55
Q

Why is the extracellular matrix in hyaline cartilage like a gell?

A

Lots of negatively charged sulfates and lots of water

  • Aggrecan
    • Protein + GAG
      • Lots of negatively charged sulfates
        • attach/attracted to water molecules

Becomes a high water content gel

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56
Q

What is the function of the type II collagen and the ground substance in hyaline cartilage?

A
  • Collagen = gives it tensile strength​
    • Do not want to rip a part
    • Type I = strength
    • Type II = lots of strength in cartilage (prevents ripping)
  • Ground substance = makes it resistant to pressure
    • want some squishiness
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57
Q

What type of cells are in each of the layers of hyaline cartilage?

A
  • Perichondrium =
    • Fibroblast or fibroblast like cells in the perochondrium
  • Hyaline cartilage =
    • chondrocytes in the lacuna (empty space like a lake artifact)
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58
Q

Why does it take a long time to repair damaged cartilage?

A
  • Cartilage is avascular (long time for repair)
  • Blood supply is in the perichondrium
  • Chondrocytes have low metabolic activity and limited ability to divide
    • pretty static
  • Chondrocytes still need nutrients, get it in the perichondrium
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59
Q

Where do new chondrocytes and matrix come from?

A

fibroblast like cells

>>>>>>

differentiate into chondroblasts

(adding more cartilage on top of other cartilage)

(apositional growth)

Can divide and lay down matrix

(some ability for chondrocytes to divide)

>>>>> Intersititial growth (inside cell)

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60
Q

What is the difference between hyaline, elastic and fibrocartilage?

A
  • Hyaline
    • Type II collagen
    • Perichondrium present
  • Elastic
    • Type II collagen and elastic fibers
    • Perichondrium present
    • Ex. epiglotis
  • Fibrocartilage
    • Type I and II collagen -> CT very strong
    • No perichondrium present
    • Ex. intervertebral discs -> super strength
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61
Q

What type of tissue is bone?

A

Connective

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62
Q

What are the components of bone and function? Cells and extracellular matrix

A
  • Cells
    • Osteoblasts - remodeling
    • Osteoclasts - remodeling
    • Osteocytes - helps ‘maintain’ matrix
    • Bone lining cells
    • Osteoprogenitor cells - gives rise to osteoblasts
  • Extracellular matrix = bone matrix
    • Fibers
    • Ground substance
      • GAGs, proteoglycans, multiadhesive glycoproteins
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63
Q

What type of collagen is in bone?

A

Type I collagen

Lots of STRENGTH

(tendons, ligaments, bone, skin, sclera, etc)

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64
Q

Explain the fiber arrangement in bone tissue and its major function

A
  • Function: STRENGTH in MULTIPLE directions
    • in layers
  • The fibers in bone are aligned in parallel, but oriented in different directions
    • Called LAMELLAR BONE
      • CONCENTRIC LAMELLAE = layers
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65
Q

What else gives bone its great strength?

A

Bone matrix is CALCIFIED

Type I collagen + ground substance = calcification

>>>>>>

Mineralized with hydroxyapatite crystals

Insoluble salt of calcium and phosphorus

= forms a crystal

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66
Q

Explain the structures of ground bone

A

Ground bone

because bone is so hard you cannot section it without getting ride of the calcium or grinding it down to see the sections

  • Layers of bone matrix
    • each of these layers = lamella
  • Osteocytes in lacunae (lake)
  • Central canal
    • Contains blood supply for osteocytes in the lacunna
    • ** Contains no capillaries**
  • Canaliculi
    • Little channels between the lacuna in the matrix of the bone
  • osteon
    • one circular bone structure
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67
Q

What is the following structure?

A

Osteocyte in a lacuna

  • Dendritic process surrounded by bone matrix

>>>>>

Within the canaliculi

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68
Q

What happens in the canaliculi?

A
  • Osteocytes are encased in mineral matrix that prevents diffusion of substances
    • Osteocytes sit in a lacuna

Nutrients: travel from central canal to osteocytes via dendritic process

Wastes: travel from osteocytes to central canal via dentritic process

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69
Q

What type of intracellular communication structure aids with the transfer of nutrients from one osteocyte to another?

A

Gap junction

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70
Q

What are the types of bone?

Name and describe

A
  • Lamellar bone
    • Compact bone
      • cortical bone = because it generally located on outer edge or cortex of bone
    • Cancellous bone (spongy, trabecular bone)
      • Looks spongy and contains trabeculae
  • Woven bone
    • Occurs during fetal development and bone repair. Then remodels to lamellar bone
    • FASTER AND EASIER TO LAY DOWN
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71
Q

Explain the structure of compact bone

A

Contain osteon

  • Contain:
    • External circumferential lamellae
    • internal circumferential lamallae
    • interstitial lamallae
    • Osteon
    • Centraol canal with blood vessels and nerve
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72
Q

Explain the structure of spongy bone (cancellous or trabecular)

A

No osteon

  • Lamellae = large circles
  • Osteocytes in lacuna
  • Canaliculi open to surface
    • Avascular and use canaliculi that open to the surface
      • get nutrients from bone marrow
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73
Q

What lines the surface of bone tissue?

A
  • Endosteum
    • Lines surface of trabeculae
  • Periosteum
    • lines outside of compact bone
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74
Q

Explain the structure of trabeculae and location of osteoprogenitor cells

A
  • Endosteum
    • Osteoprogenitor cells or bone lining cells
      • Quiesent cells not doing much
    • CT layer​
  • Periosteum
    • Osteoprogenitor or bone lining cells
      • Quiesent cells not doing much
    • Dense fibrous CT

** Dense fibrous CT connected to epithelium via Sharpey’s fibers

  • Perforating
  • Connects periosteum to the bone
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75
Q

Explain the following structures

A

Stained section of demineralized bone

  • Demineralized by removing the hydroxyapatite crystals
    • Calcium phosphate crystals removed to allow for staining
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76
Q

Identify the following structures

A

Osteocytes

Sharpey’s fibers

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77
Q

Explain the process of bone remodeling

A
  1. Resting bone
  2. Osteocytes or hormones recruite pre-osteoclasts to bone from bone marrow
  3. Osteoclasts attach to bone and resorbs the bone
  4. Osteoclasts create a resorption lacuna and release acids and enzymes to remove the bone
  5. Osteoclast moves/apoptosis
  6. Bone lining or osteoprogener cells turn into osteoblasts
    1. more cube shaped = active
  7. Osteoblasts secrete bone matrix
    1. Lay down osteoid
      1. Unmineralized bone (Type I collagen that becomes mineralized)
  8. Bone mineralizes and traps osteoblasts in matrix to form osteocytes
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78
Q

Identify the following cell types in the tissue sample

A
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79
Q

Identify the following structures in the image

A
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80
Q

Identify the following structures in the slide image

A
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81
Q

Explain the path of osteoclasts movement/remodeling through bone

A
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82
Q

Identify structures in the following slide/image

A
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83
Q

What role does osteoblasts and osteoclasts, or bone remodeling, play in the development of osteoporosis?

What exactly is osteoporosis?

A

Decreased bone mass per unit

volume of anatomical bone

-> Thinning bone over time

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84
Q

Explain the onset of osteoporosis and how bone density changes over time

A

**Why it is important to build up bone when you are younger so you have more bone you have to break down before getting to a critical level**

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85
Q

Explain a drug commonly used to fight osteoporosis, reaction and its side effects

A

Bisphosphonate drug inhibits osteoclasts

  • Side Effect:
    • Osteonecrosis of the jaw = when trauma to the bone (eg. dental surgery) occurs along with continual stress from chewing
    • Bisphosphonates disrupt bone remodeling
    • Bone has limited capacity for healing
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86
Q

What are the two types of osteogenesis

A
  • Intramembranous ossification
  • Endochondral ossification
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87
Q

What are the different shapes of bones?

A

Long bone (eg. femur)

Short bone (eg. wrist)

Flat bone (eg. skull)

Irregular bone (eg. vertebrae)

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88
Q

What type of ossification does flat bone do for development

A

Most flat bones develop via intramembranous ossification

  • inside a membrane
  • Starts out with some kind of membrane
  • bone develops in that membrane
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89
Q

Explain the process of Intramembranous Ossification

A
  1. Mesenchymal cells in CT membrane or sheet cluster
  2. Cells differentiate into osteoblasts
  3. Create an ossification center
    1. Site where you are making bone
  4. Osteoblasts secrete osteoid
    1. Type I collagen and matrix without minerals
  5. Which then become mineralized
  6. Osteocyte forms in a lacuna
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90
Q

Explain the slide containing intramembranous ossification

A

Woven bone (faster)

Newly made

Collagen in multiple directions

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91
Q

What is newly formed bone called?

A

primary bone or woven bone

NOT LAMELLAR BONE or secondary bone

WOVEN BONE

Collagen in multiple directions, instead of ordered

Because it is faster

  • Maturation stage:
    • Marrow cavity with blood vessels
    • Immature woven trabeculae
      • Collagen fibers oriented randomly
    • Mesenchymal cells condense and form the periosteum
  • Remodeling of woven bone >>> Lamellar bone
    • Collagen fibers oriented in parallel
      • Formation of cancellous or spongy bone
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92
Q

Explain endochondral ossification during fetal development

A

From cartilage >>>> to bone

DURING FETAL DEVELOPMENT and GROWTH IN LENGTH OF BONE

  1. Mesenchymal cells condense
  2. Formation of a chondrocyte (Type II Collagen)
    1. Hyaline cartilage
    2. Glassy and do not see fibers
  3. Forms a perichondrium
  4. Cartilage deteriorates and turns into bone in the primary ossification center (center long bone)
    1. Within the primary ossification center)
      1. Osteoblasts build
      2. Osteoid and bone is developed (eosinophil)
      3. Cartilage breaks down (basophilic)
    2. Initially, form woven bone in the ossification center

SECONDARY OSSIFICATION CENTERS THEN DEVELOP AT THE ENDS OF THE CARTILAGINOUS STRUCTURE

** Woven bone eventually remodels to lamellar bone

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93
Q

Explain how bone grows in width

A

APPOSITIONAL OR PERIOSTEAL GROWTH

Growth in width or thickening of a bone

  • Osteoblast lays down new bone on the surface
    • Edge of the bone instead of epiphyseal growth plate
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94
Q

Name and describe the Epiphyseal growth plate zones

A
  • Zone 1 - Hyaline cartilage
    • Resting zone
    • Cell type = chondrocytes
  • Zone 2 - Proliferation
    • Cells divide
  • Zone 3 - Hypertrophy
    • Cells are getting longer
    • Compresses the surrounding cartilaginous matrix
  • Zone 4 - Calcification
    • Chondrocytes die (apoptosis)
      • Because cartilage making is no longer necessary
      • Cartilage matrix becomes calcified (more basophilic)
  • Zone 5 - Ossification
    • ​​Blood vessels and osteoblasts invade the tissue
      • Lays down osteoid
        • Creates mineralized bone (eosinophilic)
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95
Q

What type of bone will initially be formed at the growth plate?

A

Woven bone (quick remodeling)

When epiphyseal plate is closed = epiphyseal line and no more cartilage remains in the bone

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96
Q

Which type of bone tissue would you see in a new fracture (i.e. during the repair process) and in a healed fracture?

A

New fracture = woven bone (quick bone)

Healed fracture = Lamellar bone

97
Q

What are the major systemic regulators that affect bone formation, turnover?

Name and describe

A

CALCIUM HOMEOSTASIS

  • Parathyroid hormone (PTH)
    • Stimulate osteoclast activity = breakdown
    • Occurs when blood calcium is low
      • Calcium released from hydroxyapatite crystals
  • Calcitonin
    • Tones (builds) the bone
    • Occurs when blood calcium is high
  • Calcitriol (vitamin D)
    • Increases Ca+ absorption from gut
98
Q

What occurs when a person has a vitamin D deficiency

= osteomalacia

A

Calcium does not get absorbed from the gut and then would not allow you to mineralize the bone

  • Bone becomes very dull, bowed legs, etc
99
Q

An excess of growth hormone in adults results in acromegaly. Based on these effects, growth hormone must be increasing:

A

Periosteal (or appositional) growth

(adult = no more growth at epiphyseal plate)

No more cartilage turning to bone

Instead, Bone grows on the surface

100
Q

An excess of growth hormone in a child results in gigantism. Based on these effects, growth hormone must be increasing:

A

Endochondral ossification

cartilage turning to bone

Usually at epiphyseal plate

101
Q

Explain the features of a synovial (movable) joint

A
  • Joint cavity = creates synovial fluid
  • Ligament = connected into bone periosteum to add strength
  • Articular cartilage = Hyaline
    • DOES NOT contain periosteum and no perichondrium
  • Joint capsule:
    • Make: fibrous layer and synovial membrane
102
Q

Explain how the collagen fibers in articular cartilage is arranged in the synovial joint

A

Collagen fibers are parallel to the surface

= creates a smooth surface

(Type II collagen in the hyaline cartilage)

103
Q

Where do the chondrocytes in the articular cartilage get their nutrients?

A

Synovial fluid

(NOTE: Articular cartilage does NOT contain a perichondrium)

104
Q

What are the two types of circulatory systems in the body?

What are their divisions

A

Circulatory system

  1. Cardiovascular system
    1. Heart
    2. Blood vessels
      1. Arteries
      2. Capillaries
      3. Veins
  2. Lymphatic system
105
Q

A person develops a thrombus in their femoral vein. If the clot breaks off, where will it most likely end up?

A

LUNGS

PULMONARY EMBOLISM

Not going to be able to squeeze through the capillaries in the lungs

  • First will travel into right atrium, right ventricle, then into the pulmonary artery into the lungs and get stuck
106
Q

A person develops a thrombus in their left atrium. If the clot breaks off, where will it most likely end up?

A

Brain or another organ

STROKE

107
Q

Name and describe the major layers of the heart

A
  • Endochondrium = Lines inner wall of the heart
  • Myocardium = muscle layer; functions in pumping the blood (contraction)
    • Thickest layer
      • THICKEST IN LEFT VENTRICLE = TO BODY
  • Epicardium = Lines the outer wall of the heart
108
Q

Where is the endocardium in this section of ventricle? What are the layers of the endocardium?

What is contained in each layer?

A

Endocardium = innermost of heart

  • Myoelastic layer
    • ​​Loose CT with smooth muscles
  • Sub-endocardial layer
    • ​​CT with:
      • Arteries
      • Veins
      • Nerves
      • Purkinje fibers
109
Q

What is the role of the endothelial layer lining the endocardium?

A
  • Acts as a barrier - controls the passage of material between blood and heart tissue
  • Provides a nonthrombogenic (non-clot forming) surface
    • Prevents clotting
  • Modifies cardiac performance
    • Can release different factors that affect the contraction of the myocytes
110
Q

What is the role of collagen in the endocardium and subendocardium?

A

Provides SUPPORT

111
Q

What are the following features?

Describe what they look like and why they are different

A

Purkinje fibers in the subendocardium of the ventricles

  • Do these look a little like cardiac myocytes?
    • Tend to be larger than myocytes and a little lighter in color

(have myofibrils but not as many and also contain INTERCALATED DISKS = desmosomes and gap junctions between the Purkinje fibers)

112
Q

What are Purkinje fibers and why do they look similar to, but different from cardiac myocytes?

A

Want electrical impulses to get to a lot of myocytes very quickly

  • Muscle cells that are specialized for impulses conduction instead of contraction
    • Lots of glycogen and mitochondria = not stain as well
    • Not many myocytes
113
Q

Explain the heart conduction system

A
  1. SA node (automaticity = regulatory)
    1. Generate electrical impulses = contraction
  2. AV node
    1. Slows down impulses to allow atrial contraction before ventricle contraction
  3. Bundles of His
    1. Into the branches and then into the Purkinje fibers that go to the individual myocytes for contraction of ventricles
  4. Left and right bundle branch
  5. Purkinje
    1. Sends impulses to the myocytes
  6. Ventricular contraction
114
Q

Explain what occurs if a person has damage to the endocardium layer of the heart

A
  • If endothelial layer of endocardium intact = no “sticking” of bacteria to the endocardium
  • If endothelial layer is damaged but no bacteria
    • Sterile platelet-fibrin nidus forms when platelets adhere to the endothelial layer of the endocardium and then a sterile platelet-fibrin nidus is created
  • If endothelial layer damaged but has bacteria in the blood
    • Bacteria binds to the platelet-fibrin nidus and creates a vegetation, potentially causing a death to the patient
115
Q

Name and state where the location of the valves are in the heart

A
  • AV (atrial-ventricular) valve
    • Attaches to the papillary muscle via chordae tendineae (CT)
  • Aortic semilunar valve
116
Q

While infective endocarditis can occur in the heart chambers, it most commonly occurs on the valves of the heart. Why?

A

Vegetation often found on the valves of the heart

  • Vegetations tend to develop where blood travels from an area of high pressure, through a narrow orifice, into an area of lower pressure

Due to the turbulent flow of the blood around valves causing damage to the endothelium

**All connective tissue in the valves, no muscle

117
Q

What will happen if a person has damage to the area in their ventricles containing the Purkinje fibers?

A

Cardiac arrhythmia (abnormal heart rhythm)

**Purkinje fibers = pacemaker cells of the heart!

118
Q

What would happen if a person had damage or problems with their cardiac muscle fibers (ie damage to their ventricular/atrial myocytes)

A

Decreased ventricular or atrial forces of contraction

119
Q

What would happen if a person had damage to their SA node?

A

Sinus or SA node tachycardia (rapid heart rate)

120
Q

What is the external layer of the heart? and what surrounds the entire heart?

A

Epicardium

And the surrounding pericardium or pericardial sac

121
Q

Name and describe the structure/makeup of the epicardium

A
  • Outer surface = Lined with simple squamous or cuboidal layer of mesothelium
  • Internal features:
    • Autonomic nerve
    • Adipocytes or fat cells
    • CORONARY BLOOD VESSELS
      • bypassed during bypass surgery
122
Q

Explain the feature that encases the heart

A

Pericardium or pericardial sac

  • Serous pericardium made up of:
    • Visceral layer
      • Mesothelium (right on top of the organ)
    • Parietal layer
      • Closed sac

Fluid-filled pericardial cavity (closed sac)

  • Fibrous pericardium = dense CT -> support
    • Lots of connective tissue with strength and support to the pericardial sac
123
Q

What is the function of the pericardium?

A
  1. Fixes the heart in the chest cavity
    1. Fiberous portion
  2. Protection against infection
    1. Additional layer makes it hard to get through
  3. Provides lubrication for the heart when beating
    1. Pericardial fluid = serous fluid
124
Q

If there was a pericardial effusing where fluid built up in the heart. This is caused by fluid building up in which location around the heart?

A

Between the visceral and parietal layers of the pericardium

  • it is where the fluid comes from = serous fluid
125
Q

What are the layers of the vascular wall?

A

Lumen

Tunica intama

Tunica media

Tunica adventitia

126
Q

What makes up the walls of the tunica intima

A
  1. Lumen:
  2. Endothelium + underlying basal lamina (basement membrane)
    1. Simple squamous epithelium
  3. Subendothelial layer
    1. Loose CT
  4. Internal elastic lamina
    1. Sheet of elastin with fenestrations
127
Q

What is the function of the fenestrations in the tunica intima internal elastic lamina layer

A

Fenestrations = large holes

-> allows for rapid diffusion through the vessel

128
Q

What is the function of the endothelium in the tunica intima?

A
  1. Selective permeability barrier
    1. Lipid-soluble substances - can diffuse across
    2. Water soluble substances - need a transport mechanism or go paracellularly
  2. Nonthrombogenic barrier
    1. Prevents platelets from adhering to the underlying connective tissue
      1. Angioplasty = balloon to open up the coronary artery can damage the endothelium layer which can cause clotting with platels sticking -> heart attack
  3. Modulates blood flow
    1. Releases vasoconstrictors and vasodilators
129
Q

Explain the middle layer of an artery wall

A

TUNICA MEDIA

Circumferentially arranged smooth muscles with:

  • Reticular fibers
    • (type III collagen)
  • Proteoglycans and glycoproteins
    • (ground substance in ECM)
  • Elastic fibers
    • Amount varies - stretch and recoil

External elastic lamina

  • Layers of elastic fibers
130
Q

Explain the outer layer of an artery wall

What type of cells and collagen is found in this layer?

A

Tunica adventitia or externa

  • Dense irregular connective tissue
    • Collagen and elastin
      • Type I collagen = LOTS
  • Main type of cells
    • fibroblasts = elastic fiber production
  • Main type of collagen in tunica advantitia
    • Type I collagen
131
Q

What to larger arteries also contain in the tunica advantitia or externa region?

What is the function of this?

A

VASA VASORUM

  • Function = provide blood supply to artery adventitia and media layers
  • Contains:
    • Arteries
    • Veins
    • Capillaries
    • Nerves
132
Q

How do systemic arteries differ from systemic veins?

A

Arteries are subjected to a much higher pressure than veins

  • Veins contain:
    • One way valves
    • Thinner Smooth muscle layer
    • Thicker adventitia
    • More extensive vasa vasorum
133
Q

Identify if this is an artery or a vein, identify and describe the layers

A

Artery

In fact the aorta

Lots of elastic lamina and thick Tunica media

134
Q

Identify if this is an artery or a vein, identify and describe the layers

A

Vein

Vena cava

Smaller Tunica media

Thick Tunica Adventitia

135
Q

What are the types of arteries and their functions

A
  • Conductance vessels
    • Large, elastic arteries (eg. aorta)
      • BRANCH
    • Muscular arteries (medium sized arteries)
      • BRANCH
  • Resistance vessels
    • Small arteries and arterioles
      • BRANCH
    • Capillaries
136
Q

Name the feature and describe

What is the function of this type of blood vessel?

A

Elastic artery

Function: Conduction of blood

ie. helps to store energy generated by the heart’s contraction and helps blood to flow when the heart is relaxing

137
Q

What is systole and diastole and what is going on with the heart during these two time periods?

A
  • Systole = Aorta expands or distends
    • Facilitated by elastic fibers, limited by collagen fibers
    • PRESSURE INCREASES
  • Diastole = Aorta elastic recoil and blood leaves
    • Pressure decreases
138
Q

If the elasticity of the aorta is reduced (eg. increased arterial stiffness possibly from fracture of elastic fibers with aging), what happens to systolic and diastolic pressure?

A

Systolic pressure = higher

Doesn’t allow for stretch

Diastolic pressure = lower

Doesn’t allow for reduction of area (no recoil)

139
Q

What is the following feature and describe the detailed structures and function of the tissue

A

Muscular artery

Very prominent INTERNAL ELASTIC LAMINA

  • Endothelial cells
  • Internal elastic lamina (prominent)
  • Smooth muscle cells
    • Predominate constituent of tunic media)
  • Adventitia

Function: Same as elastic arteries CONDUCTION OF BLOOD and withstand pressures

140
Q

What is the following feature and describe the detailed structures and function of the tissue

A

Small arteries and arterioles

  • Function: = resistance vessels
    • Helps determine mean arterial pressure
      • Constrict blood vessels = area smaller causing pressure to increase
      • All dialated = decrease BP
      • All constricted - increase BP
    • RIght before the capillaries
    • Controls the amount of blood going into the capillary or responsible for the relative blood flow to an organ at any given mean arterial pressure
141
Q

What are the following features?

A
142
Q

What makes up a capillary?

A

Endothelial layer (simple squamous)

Basal lamina (basement membrane)

143
Q

Name and describe the three types of capillaries

A
  • Continuous = no holes
    • Most common
    • Contain tight junctions between cells (eg.blood-brain barrier)
  • Fenestrated = small holes
    • Allow for proteins, peptides to cross (glands)
  • Sinusoid = Big holes
    • Lets RBC through (spleen)
144
Q

How do material (nutrients, O2, etc.) go from the lumen of the capillary to the interstitial space or visa versa?

A

Lipid soluble (O2) = diffuse

Some hydrophobic = transcytosis (endo/exo both)

Water and other solutes (excluding proteins) PUSH through junctional complex

145
Q

What is the advantage of fenestrated vessels?

A

More rapid, easier exchange of substances like in the kidneys

146
Q

What is unique about the following sinusoid feature?

A

Much larger than other capillaries

BOth endothelial layer and basal lamina have large holes

Large enough for cells to get through

147
Q

Where might you find sinusoids?

A

Liver, spleen and bone marrow

148
Q

Where are venules located?

A

after the capillaries

149
Q

What is the venule wall like?

A

gradually develops in tunica media

150
Q

What is the following features?

A
  • Small vein
    • thin intima with endothelial cells
    • thin media
    • adventitial blends in
  • Small muscular artery
151
Q

What is the following feature?

A

Large vein with valve

152
Q

What is the difference between arteries and veins?

A
  • Thicker Media = Medium arteries
  • Thicker adventitia = Large veins
  • Under high pressure = Arteries
  • Have valves = veins
153
Q
A

A. Aorta

Fibrillin = component of elastic fibers

154
Q

Where does the excess interstitial fluid come from?

A

FLuid leaving capillaries

155
Q

Explain the process of filtration

A

absorption + lymphatic flow lymphatic vessel

  • At the arterial end of a capillary, the sum of the hydrostatic and oncotic forces cause a net movement of material (essentially plasma) form the capillary to the surrounding interstitial tissue
  • On the venous end of the capillary, almost all of this material is reabsorbed back into the blood
  • The fluid, including proteins, left behind, enters a lymphatic capillary and it ultimately returned to the blood via the lymphatics
156
Q

Explain the structure of a lymphatic capillary

A

Endothelial lined cell

157
Q

Explain what causes the lymph to stain darker

A

Lymph is rich in proteins and therefore will be more eosinophilic

158
Q

What happens if filtration is greater than absorption?

such as if a lymph is blocked

A

Increase protein and water in interstitial space

>>>>>>>>

Non-pitting edema (when more severe)

159
Q

What is it when the lymphatic is obstructed by a worm?

A

Elephantiasis

160
Q

What is it when the filtration > absorption?

Such as when the venule is is blocked

A

Increase in hydrostatic pressure increases water in interstitial space

>>>>>>>

pitting edema

Pitting edema = when you press on the skin in the swollen area and the indentation take several seconds to relieve

161
Q
A

A. removal of axially lymph nodes from breast cancer surgery

162
Q

Where does lymph end up?

A

Larger lymphatic vessels

  • Thoracic duct
  • Right lymphatic duct

Ultimately to the bloodstream

163
Q

What helps move lymph toward the thoracic duct or right lymphatic duct?

(or prevent it from backing up)

A
  • Smooth muscles in the vessel wall
  • Valves
  • Walking and breathing (pumping motion)

Very similar to veins!

164
Q

What are the following features?

A

LV = lymphatic vessel with very thin walls

V = Venule

165
Q

What is the following feature pointed out?

A

Valves in a longitudinal section of lymphatic vessel

166
Q

What are the types of immune response and how are they broken down?

A
  • Innate
    • Non-specific
    • Fast/always present
    • No memory
  • Adaptive
    • Specific
    • Slower to develop
    • Memory
      • Humoral = antibodies
      • Cell-mediated = T cells
167
Q

What is a part of the innate immune system?

A
  • Immune cells (Innate and adaptive)
  • Mucous membranes (innate only, barriers)
  • Skin (innate only, barriers)
  • Stomach acid (innate only, barriers)
  • Saliva (innate only, barriers)
168
Q

What are cells of the innate immune system?

A
  • Kill virus-infected cells
    • Natural killer cells
  • Kill worms allergic response Histamine
    • Basophil
    • Eosinophil
    • Mast cells
  • Phagocytes kill pathogens
    • Macrophage
    • Neutrophil
  • Antigen Presenting Cells (APC)
    • Monocytes
      • Macrophage
      • Dendritic cells
169
Q

A person gets a cut on their skin, so the barrier is breached and a pathogen (bacterium) enters the blood.

What do the cells of the immune system need to do?

A
  1. Detect and identify it as foreign
  2. Communicate with other immune cells to rally an organized response
  3. Coordinate the response among all participants
  4. Destroy or suppress the invader
170
Q

The cut becomes red and swollen. This reaction is a hallmark of….???….. immunity

A

Innate immunity

171
Q

Within damaged tissue. Which cells act on the injury?

What do these cells do in response?

A

Mast cells

Macrophages

>>>>>>>>>>>>>>>>>>

Release cytokines (chemical medeators) , chemokines (communication)

these then release histamine, prostaglandins, leukotrienes

>>>>>>>>>>>>>>>>>

Inflammatory mediators

>>>>>>>>>>>>>>>>

Cause the redness and swelling

172
Q

What are cytokines and chemokines?

A

Chemotactic cytokines

Protein messengers that are released from one cell and affect the differentiation and activity of another cell

173
Q

Later, after the initial cut, there is a lot of pus in the wound. How did this happen?

A

Macrophages and neutrophils were attracted to the site of infection

THey recognized the bacteria as foreign

They phagocytized the bacteria

how?????

Monocytes in the blood differentiate to macrophages in the skin and the phagocytize the bacteria

174
Q

The immune system can differentiate between self and nonself. How?

A

Microbes have molecules that are different from hose on our cells

Collectively these different molecules are termed pathogen-associated molecule patterns (PAMPs)

175
Q

What if a person gets infected with a virus?

A

Natural killer (NK) cells are able to eliminate virally infected or tumor cells

(not going to really talk about these)

176
Q

Adaptive immunity is primarily mediated by what type of cell?

A

Lymphocytes

You have to look at the surface markers to tell if it is a T cell or a B cell, not seen in the image

177
Q

Where are lymphoblasts normally located in and what do they differentiate into? and then where do they move to?

A
  • Lymphoblasts
    • B cell
    • CD4 - T cell precursor
    • CD8 - T cell precursor
    • NK cells
  • Move to the blood in their naive cell form
178
Q

In the blood B cell, CD4 - T cell precursor, CD8 - T cell precursor, and NK cells in their naive cell form then continue to where and what do they do?

A

CD4- and CD8- move to Thymus

>>>>>>>>>>>go into>>>>>>

Connective tissue, epithelial, secondary lymphoid organs

>>>>>>>>>>>>>

Wait and look for antigen

179
Q

Describe Lymphoid tissue and its breakdown

A

Aggregates of lymphocytes

  • Within connective tissue (no capsule)
  • Surrounded by a capsule -> lymphoid organ
180
Q

Describe the breakdown between primary and secondary lymphoid tissue

A
  • Primary = where immune cells arise (made)
    • Bone marrow
    • Thymus
  • Secondary = Where immune cells get together and initiate adaptive immunity (lymphocytes)
    • ​​Appendix
    • Lymph nodes
    • Peyer’s patches
    • Spleen
    • Tonsils
181
Q

Describe what the thymus is and where does it reside?

A

Thymus = where T cells mature

182
Q

Explain the histology of the following slide and state what it is

A

Thymus

  • Contains:
    • Capsule = because it is a lymphoid organ (made of CT)
    • Septa = dividing the lobule
    • Lobule = a lobe with a cortex and medulla
    • Cortex = outside of lobule
    • Medulla = inside of lobule
183
Q

WHat type of cells are in the cortex of the thymus?

A
  • Thymocytes (developing T - cells)
  • Cortical thymic epithelial cells (TEC)
    • large euchromatic nucleus
184
Q

Describe the structure of the Thymus and the type of collagen

A

Lymph node has type III collagen to allow support but Thymus does NOT have this…

Instead, they have

Thymic epithelial cells

These cells are a support network with lots of desmosome processes

Inside the Thymic epithelial = Thymocytes

185
Q

There is one type of cell that is distinct to the thymus. What is this cell and what layer is it in?

What other cells are in this portion of the thymus?

A

Hassall Corpuscles

ONLY in the Medulla of the thymus

Medullary Thymic epithelial cells

and Thymocytes

186
Q

What is the function of thymic epithelial cells?

A

They help support the thymocytes

Aide with T cell maturation or differentiation

Positive and negative selection

187
Q

Explain the concept of positive selection in the cortex

A
  • T cell progenitor originated in bone marrow, enters from the blood to the thymus
    • Creates Thymocyte
  • Proliferation TCR gene rearrangement in the thymus and then express CD4 and CD8 =>
  • Creating CD4 and CD8
    • It contains both CD4 and CD8 it will then be a double positive thymocyte
    • It lacks a T cell receptor (TCR) and CD4 and CD8 co-receptors double negative thymocyte
  • The double positive thymocyte will then either be recognized by MHC or not recognition of MHC (does not occur in thymus)
    • If MHC is recognized => presents self-antigen on APC and Thymic epithelial cell (TEC) moves to the medulla
    • If MHC is not recognized (95% of them) then the thymocyte dies via apoptosis (neglect)

In the thymus, cortical thymic epithelial cells express a high density of MHC class I and class II molecules associated with self-peptides.

  • TCR on a double positive thymocyte binds to an MHC on cortical thymic epithelial cell, the thymocyte moves to the medulla
  • If it does not, the thymocyte undergoes apoptosis or dies by neglect
188
Q

What is the purpose of positive selection?

A

Positive selection gets rid of T cells that can’t bind to MHC proteins

  • Moderate binding

During an immune response, binding to MHC proteins is required for T cell activation

189
Q

Explain the process of negative selection (occurs in the medulla)

A

Binds with high affinity to MHC of Professional APC cells (Dendritic cells, Macrophages or less often cortical thymic epithelial cells)

  • If there is a high-affinity binding of the thymocyte with CD4, CD8 and TCR then the cell is going to apoptosis
    • Gets rid of T cells that would cause an autoimmune response (cell killer cells)
  • If there is not a high-affinity binding the surviving double positives -> Matures further to either a:
    • CD4 + cell
    • CD8+ cell
190
Q

What is the purpose of negative selection

A

Negative selection gets rid of T cells that would be auto-reactive

Exiting the thymus are naive CD4+ and CD8+ T cells that are specific for all the different antigens

191
Q

What happens to the thymus with aging?

A

Loss of thymocytes and gain of adipose tissue

Because of the aging thymus and thymocytes turning into fat cells, they helps to explain why as you get older you are more likely to get sick

192
Q

Why does the medulla of the thymus stain lighter than the cortex with H&E?

A

Loss of thymocytes by positive selection in the cortex causes the density of cells to be less in the medulla

(they do not mature into the medulla from the cortex, instead, they undergo apoptosis)

193
Q

What type of cells are normally present in the nodule of a lymphoid organ?

A

concentration of B cells

194
Q

Explain the process of activation of B cells

A
  1. APC (Dendritic or macrophage) bind to bacteria and capture antigen => Present bacterial antigen on surface
  2. MHC with bacterial antigen travels to the lymphoid tissue
  3. Bind and activate a naive CD4+ T cell
  4. Activated CD4+ helper T cell created
  5. Helps activate a naive B cell
  6. Colonal expansion of B cells, differentiate into plasma cells
  7. Enter bloodstream and are targeted to the site of inflammation
  8. Produce antibodies
195
Q

Explain the activation of cytotoxic T cells

A

Antigen from virus infected cell or tumor cell binds to MHC I or MHC II on dendritic (APC)

  • If MHC I => Bind and activates a naive CD8 T cell
  • If MHC II => bind and activate a naive CD4+ T cell
    • Helper T cell releases cytokines => leading to a strong CD8+ activation
    • Colonal expansion of activated cytotoxic CD8+ t cells
    • Functional cytotoxic T cells enter blood stream
    • Search and kill virus infected or tumor cells
196
Q

Explain the structure of a lymph node and what type of cells are located in each region

A
  • Cortex
    • Lymphoid nodules
    • B - Cells zone
  • Paracortex
    • T - cells zone
  • Medulla
    • Plasma cell zone
197
Q

Explain the flow of lymph in a lymph node

A
  1. Afferent lymphatic vessel lymph flows into the
  2. Subcapsular sinus
  3. Travels into the trabecular sinus
  4. In to the medullary sinus (between the medullary cords)
  5. Out the hilum (efferent lymphatic vessel)
198
Q

Explain the flow of cells and antigens in lymph into, through and out of the lymph node

A

lymphocyte, dendritic cell antigen travels into the

afferent lymphatic vessel

Travels through the sinuses

Go back and forth between sinus and parenchyma (functional tissue)

Waiting for antigen

199
Q
A
200
Q
A
201
Q
A
202
Q

Explain another location where lymphocytes, APCs and antigens can enter the lymph node

A

THOUGH THE BLOOD

  • Comes in through the blood and then high endothelial venule in the paracortex
  • is where they enter into the medulla/cortex
    • Lymphocytes can now emit into the parenchyma (functional tissue)
203
Q

What is the following cell and what does it do?

A

High endothelial venules (HEV’s)

in the paracortex

  • Lymphocytes can now emit into the parenchyma
204
Q

What are the following cells in the figure?

A

High endothelial venule (HEV’s)

  • Lymphocytes crossing the wall
  • Endothelial cells
    • Cuboidal or columnar

ONLY FOUND IN PARACORTEX OF LYMPH NODE

205
Q

Where do B cells and T cells that enter a lymph node migrate to?

A

B cells = cortex (lymphoid nodule or follicle, not active)

T cells = paracortex

206
Q

In a primary lymphoid nodule, what is occupying it?

A

Full of naive B cells

NOT ACTIVE

207
Q

In a secondary lymphoid nodule, what cells are occumpying it?

A

B cells -> ACTIVE

Outer follicular mantel

Inner germinal center

-> proliferating B cells (turning into plasma cells)

LARGER, MORE EUCHROMATIC CELLS

(darker mantel)

208
Q
A
209
Q

Lymph nodes also contain reticular fibers. What are they?

A

Lots of reticular fibers (TYPE III COLLAGEN)

  • Trabecula
210
Q

What are the following cells?

A

Reticular fibers and cells of lymphoid tissues

(Fibroblast-like reticular cells)

211
Q

What are the following organs?

A

SPLEEN

(artery and vein)

stomach

212
Q

Besides being a site where immune cells get together to initiate adaptive immunity, what is another major function of the spleen?

A

Destroy aged erythrocytes (RBC)

213
Q

What is the spleen and what does it filter?

A
  • What is it?
    • Lymphoid tissue and a lymphoid organ (contains a capsule)
  • What does it filter?
    • Blood
214
Q

What are the features of the spleen?

A
  • White pulp
    • ​​Immune cells (T-cells, B-Cells, APC)
  • Red pulp
  • Trabecula
    • going in, CT
    • Channel before sinus -> now blood vessel
  • Capsule
  • Trabecular artery and vein
215
Q

What is the following feature?

A

White pulp in the spleen

Immune cells

(T-cells, B-cells, macrophages, Dendritic cells)

  • Central arteriole
  • PALS = mostly T cells
  • White pulp = mostly B cells
216
Q

Explain the following structures

A
  • Marginal zone = macrophages and dendritic cells
  • Nodule = B cell zone
  • Periarteriolar lymphoid sheath (PALS) = T cell zone
217
Q

Describe Red pulp

A

Blood filled sinuses (large capillaries) surrounding splenic cords

218
Q

Explain the structures in the sinusoid and splenic cords of red pulp

A
  • Sinusoids = splenic sinus = blood vessel
  • Splenic cords
    • Reticular tissue = Type III collagen
      • Fibroblasts
    • Macrophages
      • Phagocytic cells get rid of dead RBC
    • Lymphocytes and other blood cells
219
Q

Explain the flow of blood in the white pulp of the spleen

A

Travels from the

1. Trabecular artery

2. Into central arteriole

3. to the marginal zone sinuses

(termination spot = blind end)

220
Q

Explain what occurs in the marginal zone sinuses

A

Cells, antigens, pathogens get into the marginal zone through the sinus

  • Antigens, pathogens -> picked up by macrophages, dendritic cells (activate T, B cells)
  • The rest continues into the red pulp
221
Q

Explain the flow of blood in the red pulp of the spleen

A

Goes from the trabecular artery

into the central arteriole

into the splenic sinus

into the penicillar arterioles

**Blood that enters the red pulp, percolates through and then reenters the blood via the venous sinus

222
Q

Explain the movement of blood cells into splenic sinusoids

A

Stave cells = unusual endothelial cells (blood cells can reenter)

Macrophages in spleen (phagocytose older damaged red blood cells)

Reticular fibers help hold in the sinusoid

Space is big enough for white cells and healthy erythrocytes (flexible cells) to pass through

223
Q

What is the purpose of blood ‘percolating through’ the red pulp?

A

Phagocytic cells in the splenic cords (macrophages) remove debris, old and damaged red blood cells, other blood cells and microorganisms, thereby filtering the blood

224
Q
A
225
Q
A
226
Q
A
227
Q
A
228
Q
A
229
Q

What are the mucosa-associated lymphoid tissue

A
  • Isolated lymphoid nodules
  • Peyer’s patches
    • Group of nodules together
  • Tonsils
  • Appendix
230
Q

Identify the following structures

A

Palatine tonsils

  • Crypt
  • Epithelium
231
Q

What epithelium overlies the palatine tonsils in the posterior lateral walls of the oral cavity?

What are the dark blue cells?

A

CT

Stratified squamous epithelium (keratinized)

Dark blue cells = lymphocytes (lots of bacteria in mouth

232
Q

Identify the structures

A
233
Q

What other cells are found in tonsils?

A

B-cells

T-cells

Dendritic cells

Macrophages

234
Q

Pharyngeal tonsils are in the posterior wall of the nasopharynx. What type of epithelial layer covers most of these tonsils?

A

Pseudostratified with cilia

235
Q

Lingual tonsils are on the posterior surface of the tongue. What type of epithelial layer covers most of these tonsils?

A

Stratified squamous = lots of protection

236
Q

What is this a cross section of?

A

Cross section of ileum - Peyer’s patch = ilium

(lymphoid nodules)

237
Q

What type of special cells are in the peyer’s patch?

A

M cell

238
Q

What does the M cell do?

A

Antigen enters attaches to the dendritic cell and then activates adaptive immunity

(in the GI track) the largest part of immune response because the food we eat is not sterile

Uses Transcytosis

239
Q
A

D1 Histology (1 decks)

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