Written Exam 2 Flashcards
(239 cards)
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
2
Q
What layer of the skin are epithelial cells found?
A
Epidermis
(epi = epi)
3
Q
Name and describe the layers that make up the skin
A
- Epidermis (Epi = on top of)
- Dermis
- CT under the epidermis
- Hypodermis (hypo = below)
- CT under the dermis
- Lots of adipose tissue!
- CT under the dermis
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
- Found in palm of hands and bottom of feet
-
Thin skin:
- Found everywhere on skin but palms of hands and bottom of feet
- Skinnier epidermis
- Not as much keratinized epithelium
- Thicker dermis
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
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)
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
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
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)
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
11
Q
Remember: intermediate filaments are involved in intracellular adhesion
Which type of junction involves the intermediate filament?
A
Desmosomes
= integrins
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
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
-
Euchromatic = active
- Looks prickly or spiny = cytoplasmic extension
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
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
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
- Free filaggrin binds to keratin intermediate filaments, causing aggregation into macrofibrils
-
Lipids and other substances are secreted from lamellar granules
- forming a lipid barrier encircling the cell
- Lipid + filaggrin + keratin matrix = important skin barrier
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
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
19
Q
What are the following structures in this slide?
A
stratum lucidium = light layer
stratum granulosum = dark layer
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
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
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
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
24
Q
What are these brown stained cells?
A
Langerhans Cells
- Immune cells
Type of dendritic cells
25
Explain how langerhan cells, or dendritic cells, are involved in immune response
Immune cells
Phagocytize antigen
\>\>\>\>\>
move to the lymph node
\>\>\>\>\>\>
Present the antigen to lymphocytes
START THE IMMUNE RESPONSE
26
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?
***_Filaggrin_***
**rash development and holes in skin**
Because it deals with keratinization and is the cutaneous barrier
27
What features can be found in the dermis of the skin?
Blood vessels
Connective tissue
Hair
Nerves
Sebaceous and sweat glands
Sensory receptors
28
What do you notice about the interface between the epidermis and dermis?
What are their functions?
***_Dermal Papilla_*** = bumps up from the dermis
***_Epidermal Ridge_*** = Pokes down from the epidermis
***_Strength_*** - ie reinforce the dermal-epidermal junction
29
What are the two following layers in the thin skin sample
* **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
30
What type of collagen is found in the dermis?
***_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
31
What are the two types of sensory receptors in the skin?
Nerve Endings
* ***_Not encapsulated_***
* ***_Encapsulated (mylinated)_***
* *_Collagen_* and modified *_schwann cells_*
* Schwann cells = form myelin sheath
32
What is the function of free nerve endings and where are they located?
Free nerve endings = sensory neurons
***_Location_*** = epidermis
***_Function:_*** Sense pain, temperature, itching, light pressure (touch)
33
What is the function of Merkel cells and where are they located?
***_Location_***: Scattered throughout basal layer of epidermis which is connected to the
merkel (tactile) disc
***_Function_***: Sense light touch
***_Non-encapsulated = simple nerve ending_***
34
What is the function of root hair plexus nerves? Where are they located?
***_Location_***: Nerves wrapped around the plexus of a hair
***_Function_***: sense hair movement
35
What are the two types of corpuscles that are found in the dermis and where in the dermis are they located?
* ***_Meissner corpuscle_***
* Sits in the dermal papilla
* ***_Pacinian Corpuscle_***
* Deeper in the dermis
36
What is the following feature?
***_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
37
What is the following feature and explain function, location, details
***_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
38
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?
Mast cells degranulate and release histamine
mast cells are in the skin!!
39
What causes itching?
Free nerve endings
1. Histamine release
2. Histamine binds to H1 receptor
3. Itching feeling
40
Explain the anatomy around the hair follicle
* ***_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
41
Explain the anatomy of an oblique section of a hair follicle
***_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)
42
Explain the anatomy of a cross section of a hair follicle
\*\*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)
43
What is the following feature and where are they located?
Why does the feature not stain?
***_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_***
44
How is sebum secrted into the hair follicle with sebaceous gland?
Holocrine secretion
45
What type of glands are sebaceous glands?
Branched acini
46
Name and the following features in the image and where they are located
* Duct opens to surface
* **Eccrine sweat gland** (All over the body)
* Duct opens to hair follicle
* **Apocrine sweat gland** (axillary and perineal regions)
47
What is the following structure?
What are the following features in the structure
***_Eccrine sweat gland_***
* **Small lumen**
* **Cuboidal** epithelium with underlying myoepithelial cells
* **Duct**
48
What is the following structure?
What features make up the structure?
***_Apocrine sweat gland_***
* **Large lumen**
* **Cuboidal epithelium** with underlying myoepithelial cells
49
what type of tissue is cartilage?
Connective tissue
50
What are the types of cartilage and where are they found?
1. ***_Hyaline_*** (blue)
1. Articular cartilage (ie. Joints)
2. ***_Fibrocartilage_*** (red)
1. Vertebral disks
3. ***_Elastic_*** (purple)
1. Ear
51
What is the following features in the image?
* ***_Perichondrium_***
* Peri = around
* chondro = cartilage
* ***_Hyaline cartilage_***
* Dark spots inside cartilage = **chondrocytes**
* cells of cartilage
52
What is the following picture of? name and describe the features of the tissue
***_Hyaline cartilage_***
* Very glassy
* Lots of extracellular matrix
* Contains lots of condracytes
53
Does the extracellular matrix in the perichondrium look the same as the ECM in hyaline cartilage?
Describe the tissues in the cartilage layers
NO
* Perichondrium:
* Dense CT
* Type I collagen
* Hyaline cartilage:
* Type II collagen fibrils
* Lots of ground substance
* forms a gel
54
Why does the extracellular matrix in hyaline cartilage appear more purple?
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
55
Why is the extracellular matrix in hyaline cartilage like a gell?
***_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_
56
What is the function of the type II collagen and the ground substance in hyaline cartilage?
* ***_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
57
What type of cells are in each of the layers of hyaline cartilage?
* ***_Perichondrium_*** =
* Fibroblast or fibroblast like cells in the perochondrium
* ***_Hyaline cartilage_*** =
* chondrocytes in the lacuna (empty space like a lake artifact)
58
Why does it take a long time to repair damaged cartilage?
* 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
59
Where do new chondrocytes and matrix come from?
***_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)
60
What is the difference between hyaline, elastic and fibrocartilage?
* ***_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
61
What type of tissue is bone?
Connective
62
What are the components of bone and function? Cells and extracellular matrix
* ***_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
63
What type of collagen is in bone?
***_Type I collagen_***
Lots of STRENGTH
(tendons, ligaments, bone, skin, sclera, etc)
64
Explain the fiber arrangement in bone tissue and its major function
* 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
65
What else gives bone its great strength?
***_Bone matrix is CALCIFIED_***
**Type I** collagen + **ground substance** = calcification
\>\>\>\>\>\>
Mineralized with **hydroxyapatite crystals**
Insoluble salt of calcium and phosphorus
= forms a crystal
66
Explain the structures of ground bone
***_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
67
What is the following structure?
***_Osteocyte in a lacuna_***
* **Dendritic process** surrounded by bone matrix
\>\>\>\>\>
**Within the canaliculi**
68
What happens in the canaliculi?
* 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
69
What type of intracellular communication structure aids with the transfer of nutrients from one osteocyte to another?
Gap junction
70
What are the types of bone?
Name and describe
* ***_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
71
Explain the structure of compact bone
***_Contain osteon_***
* Contain:
* External circumferential lamellae
* internal circumferential lamallae
* interstitial lamallae
* Osteon
* Centraol canal with blood vessels and nerve
72
Explain the structure of spongy bone (cancellous or trabecular)
***_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
73
What lines the surface of bone tissue?
* ***_Endosteum_***
* Lines surface of **trabeculae**
* ***_Periosteum_***
* lines outside of **compact bone**
74
Explain the structure of trabeculae and location of osteoprogenitor cells
* ***_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**
75
Explain the following structures
***_Stained section of demineralized bone_***
* Demineralized by removing the **hydroxyapatite crystals**
* Calcium phosphate crystals removed to allow for staining
76
Identify the following structures
Osteocytes
Sharpey's fibers
77
Explain the process of bone remodeling
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**
78
Identify the following cell types in the tissue sample
79
Identify the following structures in the image
80
Identify the following structures in the slide image
81
Explain the path of osteoclasts movement/remodeling through bone
82
Identify structures in the following slide/image
83
What role does osteoblasts and osteoclasts, or bone remodeling, play in the development of osteoporosis?
What exactly is osteoporosis?
Decreased bone mass per unit
volume of anatomical bone
-\> Thinning bone over time
84
Explain the onset of osteoporosis and how bone density changes over time
\*\*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\*\*
85
Explain a drug commonly used to fight osteoporosis, reaction and its side effects
***_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**
86
What are the two types of osteogenesis
* Intramembranous ossification
* Endochondral ossification
87
What are the different shapes of bones?
Long bone (eg. femur)
Short bone (eg. wrist)
Flat bone (eg. skull)
Irregular bone (eg. vertebrae)
88
What type of ossification does flat bone do for development
Most ***_flat bones_*** develop via ***_intramembranous ossification_***
- inside a membrane
* **Starts out with some kind of membrane**
* **bone develops in that membrane**
89
Explain the process of Intramembranous Ossification
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
90
Explain the slide containing intramembranous ossification
***_Woven bone (faster)_***
Newly made
Collagen in multiple directions
91
What is newly formed bone called?
***_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
92
Explain endochondral ossification during fetal development
***_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
93
Explain how bone grows in width
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
94
Name and describe the Epiphyseal growth plate zones
* ***_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)
95
What type of bone will initially be formed at the growth plate?
Woven bone (quick remodeling)
When epiphyseal plate is closed = epiphyseal line and no more cartilage remains in the bone
96
Which type of bone tissue would you see in a new fracture (i.e. during the repair process) and in a healed fracture?
New fracture = woven bone (quick bone)
Healed fracture = Lamellar bone
97
What are the major systemic regulators that affect bone formation, turnover?
Name and describe
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
What occurs when a person has a vitamin D deficiency
= osteomalacia
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
An excess of growth hormone in adults results in acromegaly. Based on these effects, growth hormone must be increasing:
***_Periosteal (or_*** ***_appositional_******_) growth_***
(adult = no more growth at epiphyseal plate)
No more cartilage turning to bone
Instead, Bone grows on the surface
100
An excess of growth hormone in a child results in gigantism. Based on these effects, growth hormone must be increasing:
***_Endochondral ossification_***
cartilage turning to bone
Usually at epiphyseal plate
101
Explain the features of a synovial (movable) joint
* ***_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
Explain how the collagen fibers in articular cartilage is arranged in the synovial joint
Collagen fibers are parallel to the surface
= creates a smooth surface
(Type II collagen in the hyaline cartilage)
103
Where do the chondrocytes in the articular cartilage get their nutrients?
***_Synovial fluid_***
(NOTE: Articular cartilage does NOT contain a perichondrium)
104
What are the two types of circulatory systems in the body?
What are their divisions
Circulatory system
1. ***_Cardiovascular system_***
1. Heart
2. Blood vessels
1. Arteries
2. Capillaries
3. Veins
2. ***_Lymphatic system_***
105
A person develops a thrombus in their femoral vein. If the clot breaks off, where will it most likely end up?
***_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
A person develops a thrombus in their left atrium. If the clot breaks off, where will it most likely end up?
Brain or another organ
STROKE
107
Name and describe the major layers of the heart
* ***_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
Where is the endocardium in this section of ventricle? What are the layers of the endocardium?
What is contained in each layer?
Endocardium = innermost of heart
* ***_Myoelastic layer_***
* ***__***Loose CT with smooth muscles
* ***_Sub-endocardial layer_***
* ***__***CT with:
* Arteries
* Veins
* Nerves
* Purkinje fibers
109
What is the role of the endothelial layer lining the endocardium?
* ***_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
What is the role of collagen in the endocardium and subendocardium?
Provides SUPPORT
111
What are the following features?
Describe what they look like and why they are different
***_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
What are Purkinje fibers and why do they look similar to, but different from cardiac myocytes?
***_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
Explain the heart conduction system
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
Explain what occurs if a person has damage to the endocardium layer of the heart
* 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
Name and state where the location of the valves are in the heart
* ***_AV (atrial-ventricular) valve_***
* Attaches to the papillary muscle via chordae tendineae (CT)
* ***_Aortic semilunar valve_***
116
While infective endocarditis can occur in the heart chambers, it most commonly occurs on the valves of the heart. Why?
***_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
What will happen if a person has damage to the area in their ventricles containing the Purkinje fibers?
Cardiac arrhythmia (abnormal heart rhythm)
\*\*Purkinje fibers = pacemaker cells of the heart!
118
What would happen if a person had damage or problems with their cardiac muscle fibers (ie damage to their ventricular/atrial myocytes)
Decreased ventricular or atrial forces of contraction
119
What would happen if a person had damage to their SA node?
Sinus or SA node tachycardia (rapid heart rate)
120
What is the external layer of the heart? and what surrounds the entire heart?
***_Epicardium_***
And the surrounding **pericardium or pericardial sac**
121
Name and describe the structure/makeup of the epicardium
* 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
Explain the feature that encases the heart
***_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
What is the function of the pericardium?
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
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?
Between the ***_visceral and parietal layers of the pericardium_***
- it is where the fluid comes from = serous fluid
125
What are the layers of the vascular wall?
Lumen
Tunica intama
Tunica media
Tunica adventitia
126
What makes up the walls of the tunica intima
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
What is the function of the fenestrations in the tunica intima internal elastic lamina layer
***_Fenestrations = large holes_***
-\> allows for ***_rapid diffusion_*** through the vessel
128
What is the function of the endothelium in the tunica intima?
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
Explain the middle layer of an artery wall
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
Explain the outer layer of an artery wall
What type of cells and collagen is found in this layer?
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
What to larger arteries also contain in the tunica advantitia or externa region?
What is the function of this?
VASA VASORUM
* Function = provide blood supply to artery adventitia and media layers
* Contains:
* Arteries
* Veins
* Capillaries
* Nerves
132
How do systemic arteries differ from systemic veins?
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
Identify if this is an artery or a vein, identify and describe the layers
Artery
In fact the aorta
Lots of elastic lamina and thick Tunica media
134
Identify if this is an artery or a vein, identify and describe the layers
Vein
Vena cava
Smaller Tunica media
Thick Tunica Adventitia
135
What are the types of arteries and their functions
* Conductance vessels
* ***_Large, elastic arteries_*** (eg. aorta)
* BRANCH
* ***_Muscular arteries_*** (medium sized arteries)
* BRANCH
* Resistance vessels
* ***_Small arteries and arterioles_***
* BRANCH
* ***_Capillaries_***
136
Name the feature and describe
What is the function of this type of blood vessel?
***_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
What is systole and diastole and what is going on with the heart during these two time periods?
* ***_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
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?
***_Systolic pressure = higher_***
Doesn't allow for stretch
***_Diastolic pressure = lower_***
Doesn't allow for reduction of area (no recoil)
139
What is the following feature and describe the detailed structures and function of the tissue
***_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
What is the following feature and describe the detailed structures and function of the tissue
***_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
What are the following features?
142
What makes up a capillary?
Endothelial layer (simple squamous)
Basal lamina (basement membrane)
143
Name and describe the three types of capillaries
* ***_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
How do material (nutrients, O2, etc.) go from the lumen of the capillary to the interstitial space or visa versa?
Lipid soluble (O2) = *_diffuse_*
Some hydrophobic = *_transcytosis_* (endo/exo both)
Water and other solutes (excluding proteins) PUSH through junctional complex
145
What is the advantage of fenestrated vessels?
More rapid, easier exchange of substances like in the kidneys
146
What is unique about the following sinusoid feature?
Much larger than other capillaries
BOth endothelial layer and basal lamina have large holes
Large enough for cells to get through
147
Where might you find sinusoids?
Liver, spleen and bone marrow
148
Where are venules located?
after the capillaries
149
What is the venule wall like?
gradually develops in tunica media
150
What is the following features?
* Small vein
* thin intima with endothelial cells
* thin media
* adventitial blends in
* Small muscular artery
151
What is the following feature?
Large vein with valve
152
What is the difference between arteries and veins?
* Thicker Media = Medium arteries
* Thicker adventitia = Large veins
* Under high pressure = Arteries
* Have valves = veins
153
A. Aorta
Fibrillin = component of elastic fibers
154
Where does the excess interstitial fluid come from?
FLuid leaving capillaries
155
Explain the process of filtration
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
Explain the structure of a lymphatic capillary
Endothelial lined cell
157
Explain what causes the lymph to stain darker
Lymph is rich in proteins and therefore will be more eosinophilic
158
What happens if filtration is greater than absorption?
such as if a lymph is blocked
Increase protein and water in interstitial space
\>\>\>\>\>\>\>\>
Non-pitting edema (when more severe)
159
What is it when the lymphatic is obstructed by a worm?
Elephantiasis
160
What is it when the filtration \> absorption?
Such as when the venule is is blocked
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
A. removal of axially lymph nodes from breast cancer surgery
162
Where does lymph end up?
Larger lymphatic vessels
* Thoracic duct
* Right lymphatic duct
Ultimately to the bloodstream
163
What helps move lymph toward the thoracic duct or right lymphatic duct?
(or prevent it from backing up)
* Smooth muscles in the vessel wall
* Valves
* Walking and breathing (pumping motion)
Very similar to veins!
164
What are the following features?
LV = lymphatic vessel with very thin walls
V = Venule
165
What is the following feature pointed out?
Valves in a longitudinal section of lymphatic vessel
166
What are the types of immune response and how are they broken down?
* ***_Innate_***
* Non-specific
* Fast/always present
* No memory
* ***_Adaptive_***
* Specific
* Slower to develop
* Memory
* Humoral = antibodies
* Cell-mediated = T cells
167
What is a part of the innate immune system?
* Immune cells (Innate and adaptive)
* Mucous membranes (innate only, barriers)
* Skin (innate only, barriers)
* Stomach acid (innate only, barriers)
* Saliva (innate only, barriers)
168
What are cells of the innate immune system?
* 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
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?
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
The cut becomes red and swollen. This reaction is a hallmark of....???..... immunity
Innate immunity
171
Within damaged tissue. Which cells act on the injury?
What do these cells do in response?
Mast cells
Macrophages
\>\>\>\>\>\>\>\>\>\>\>\>\>\>\>\>\>\>
Release cytokines (chemical medeators) , chemokines (communication)
these then release histamine, prostaglandins, leukotrienes
\>\>\>\>\>\>\>\>\>\>\>\>\>\>\>\>\>
Inflammatory mediators
\>\>\>\>\>\>\>\>\>\>\>\>\>\>\>\>
Cause the redness and swelling
172
What are cytokines and chemokines?
Chemotactic cytokines
Protein messengers that are released from one cell and affect the differentiation and activity of another cell
173
Later, after the initial cut, there is a lot of pus in the wound. How did this happen?
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
The immune system can differentiate between self and nonself. How?
Microbes have molecules that are different from hose on our cells
Collectively these different molecules are termed **pathogen-associated molecule patterns (PAMPs)**
175
What if a person gets infected with a virus?
Natural killer (NK) cells are able to eliminate virally infected or tumor cells
(not going to really talk about these)
176
Adaptive immunity is primarily mediated by what type of cell?
***_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
Where are lymphoblasts normally located in and what do they differentiate into? and then where do they move to?
* Lymphoblasts
* B cell
* CD4 - T cell precursor
* CD8 - T cell precursor
* NK cells
* Move to the blood in their naive cell form
178
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?
CD4- and CD8- move to Thymus
\>\>\>\>\>\>\>\>\>\>\>go into\>\>\>\>\>\>
Connective tissue, epithelial, secondary lymphoid organs
\>\>\>\>\>\>\>\>\>\>\>\>\>
Wait and look for antigen
179
Describe Lymphoid tissue and its breakdown
Aggregates of lymphocytes
* Within connective tissue (no capsule)
* Surrounded by a capsule -\> lymphoid organ
180
Describe the breakdown between primary and secondary lymphoid tissue
* ***_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
Describe what the thymus is and where does it reside?
Thymus = where T cells mature
182
Explain the histology of the following slide and state what it is
***_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
WHat type of cells are in the cortex of the thymus?
* ***_Thymocytes_*** (developing T - cells)
* ***_Cortical thymic epithelial cells_*** (TEC)
* large euchromatic nucleus
184
Describe the structure of the Thymus and the type of collagen
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
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?
***_Hassall Corpuscles_***
ONLY in the Medulla of the thymus
***Medullary Thymic epithelial cells***
***and Thymocytes***
186
What is the function of thymic epithelial cells?
**They help support the thymocytes**
**Aide with T cell maturation or differentiation**
**Positive and negative selection**
187
Explain the concept of positive selection in the cortex
* 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
What is the purpose of positive selection?
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
Explain the process of negative selection (occurs in the medulla)
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
What is the purpose of negative selection
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
What happens to the thymus with aging?
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
Why does the medulla of the thymus stain lighter than the cortex with H&E?
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
What type of cells are normally present in the nodule of a lymphoid organ?
concentration of B cells
194
Explain the process of activation of B cells
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
Explain the activation of cytotoxic T cells
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
Explain the structure of a lymph node and what type of cells are located in each region
* ***_Cortex_***
* Lymphoid nodules
* B - Cells zone
* ***_Paracortex_***
* T - cells zone
* ***_Medulla_***
* Plasma cell zone
197
Explain the flow of lymph in a lymph node
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
Explain the flow of cells and antigens in lymph into, through and out of the lymph node
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
200
201
202
Explain another location where lymphocytes, APCs and antigens can enter the lymph node
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
What is the following cell and what does it do?
High endothelial venules (HEV's)
in the paracortex
- Lymphocytes can now emit into the parenchyma
204
What are the following cells in the figure?
High endothelial venule (HEV's)
* Lymphocytes crossing the wall
* Endothelial cells
* Cuboidal or columnar
ONLY FOUND IN PARACORTEX OF LYMPH NODE
205
Where do B cells and T cells that enter a lymph node migrate to?
***_B cells = cortex_*** (lymphoid nodule or follicle, not active)
***_T cells = paracortex_***
206
In a primary lymphoid nodule, what is occupying it?
Full of naive B cells
NOT ACTIVE
207
In a secondary lymphoid nodule, what cells are occumpying it?
B cells -\> ACTIVE
Outer follicular mantel
Inner germinal center
-\> proliferating B cells (turning into plasma cells)
LARGER, MORE EUCHROMATIC CELLS
(darker mantel)
208
209
Lymph nodes also contain reticular fibers. What are they?
Lots of reticular fibers (TYPE III COLLAGEN)
- Trabecula
210
What are the following cells?
Reticular fibers and cells of lymphoid tissues
(Fibroblast-like reticular cells)
211
What are the following organs?
SPLEEN
(artery and vein)
stomach
212
Besides being a site where immune cells get together to initiate adaptive immunity, what is another major function of the spleen?
Destroy aged erythrocytes (RBC)
213
What is the spleen and what does it filter?
* What is it?
* Lymphoid tissue and a lymphoid organ (contains a capsule)
* What does it filter?
* Blood
214
What are the features of the spleen?
* ***_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
What is the following feature?
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
Explain the following structures
* Marginal zone = macrophages and dendritic cells
* Nodule = B cell zone
* Periarteriolar lymphoid sheath (PALS) = T cell zone
217
Describe Red pulp
Blood filled sinuses (large capillaries) surrounding splenic cords
218
Explain the structures in the sinusoid and splenic cords of red pulp
* 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
Explain the flow of blood in the white pulp of the spleen
Travels from the
**1. Trabecular artery**
**2. Into central arteriole**
**3. to the marginal zone sinuses**
(termination spot = blind end)
220
Explain what occurs in the marginal zone sinuses
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
Explain the flow of blood in the red pulp of the spleen
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
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Explain the movement of blood cells into splenic sinusoids
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
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What is the purpose of blood 'percolating through' the red pulp?
Phagocytic cells in the splenic cords (macrophages) remove debris, old and damaged red blood cells, other blood cells and microorganisms, thereby filtering the blood
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What are the mucosa-associated lymphoid tissue
* Isolated lymphoid nodules
* Peyer's patches
* Group of nodules together
* Tonsils
* Appendix
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Identify the following structures
Palatine tonsils
* Crypt
* Epithelium
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What epithelium overlies the palatine tonsils in the posterior lateral walls of the oral cavity?
What are the dark blue cells?
CT
Stratified squamous epithelium (keratinized)
Dark blue cells = lymphocytes (lots of bacteria in mouth
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Identify the structures
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What other cells are found in tonsils?
B-cells
T-cells
Dendritic cells
Macrophages
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Pharyngeal tonsils are in the posterior wall of the nasopharynx. What type of epithelial layer covers most of these tonsils?
Pseudostratified with cilia
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Lingual tonsils are on the posterior surface of the tongue. What type of epithelial layer covers most of these tonsils?
Stratified squamous = lots of protection
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What is this a cross section of?
Cross section of ileum - Peyer's patch = ilium
(lymphoid nodules)
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What type of special cells are in the peyer's patch?
M cell
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What does the M cell do?
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
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