Histology Lectures Combined Flashcards
Identify the 5 layers of the epidermis in thick skin (palms)
Shows the small intestine and the lamina propria
* Def: thin layer of loose, connective tissue, blood vessels, and nerve endings; immediately under the epithelial surface
C= capillary
F = fibroblast
* Connective tissue is primarily made up of the ECM
* ECM has organized bundles of fibers (pink)
* Ground substance is pale
Three components of ground substance
Ground substance:
1. Glycosaminoglycans (hyaluronic acid & the sulfates)
2. Proteoglycans
3. Glycoproteins (fibronectin, laminin)
Collagen type I
Reticular fibers (type III collagen)
* Found in the bone marrow, lymph nodes, spleen, skin, smooth muscle cells
Basal cell carcinomas usually start in the _ layer of the skin
Basal cell carcinomas usually start in the basale layer of the skin
* Develop on skin exposed areas
* Slow growing
Squamous cell carcinoma is found in _ layer of the skin
Squamous cell carcinoma is found in the outer layers of the epidermis
* Continuously sloughed off
Which skin type lacks hair follicles and sebaceous glands?
Thick skin
What is the structure marked As?
Eccrine sweat gland (coiled)
The _ are the most predominant cell type in the epidermis; they are mitotically active and helping the dermis to regenerate every 30 days
The keratinocytes are the most predominant cell type in the epidermis; they are mitotically active and helping the dermis to regenerate every 30 days
What do we mean when we say basal keratinocytes or basal cells?
Basal keratinocytes or basal cells are keratinocytes on the basement membrane
_ is an autoimmune disease against desmoglein
Pemphigus vulgaris is an autoimmune disease against desmoglein
* Desmoglein is a component of desmosomes
(Pemphigus vulgaris/ Bullous Pemphigoid) is potentially fatal
Pemphigus vulgaris is potentially fatal
Bullous pemphigoid is an autoimmune disease against _
Bullous pemphigoid is an autoimmune disease against hemidesmosomes
* Less severe than pemphigus vulgaris
_ usually presents with flaccid bullae in the skin and oral mucosa
Pemphigus vulgaris usually presents with flaccid bullae in the skin and oral mucosa
_ usually presents with tense bullae in the skin but not oral mucosa
Bullous pemphigoid usually presents with tense bullae in the skin but not oral mucosa
Where do we find melanocytes?
Melanocytes are found in the stratum basale
* They synthesize melanin in melanosomes and transfer it to adjacent keratinocytes
Langerhan cells
Langerhan cells are dendritic cells
* Appear primarily in the stratum spinosum
* But can be in any epidermal layer
* Appear pale with “comma like” cytoplasmic process and indented nucleus
* Have birbeck granules
* They act as antigen-presenting cells in immune responses
We find merkel cells in the _ layer
We find merkel cells in the stratum basale
* Sensory mechanoreceptors
* Pale cytoplasm + dense cored granules
The _ layer contains proteins that bind keratin filaments together
The stratum granulosum layer contains proteins that bind keratin filaments together
* Within keratohyalin granules
What is a unique finding in the stratum spinosum?
Keratinocytes contain membrane-coating granules and are connected to one another via desmosomes
* Granules are releasing lipids between cells to create impermeability to water
Classify the type of connective tissue of the epidermis
Epidermis is stratifed squamous keratinized epithelium
Classify the type of connective tissue of the dermis
Dermis is dense, irregular connective tissue
What are the structural components of the papillary layer?
Papillary layer: thin, loosely arranged fibers
* Type I collagen
* Type III collagen
* Elastic fibers
* Contains meissner corpuscles (fine touch)
What are the structural components of the reticular layer?
Reticular layer has dense collagen bundles and thick elastic fibers
* Type I collagen
* Arteries, veins, lymphatics
* Pacinian corpuscles (pressure, vibration)
* Sweat glands, hair follicles, sebaceous glands
Vascular Ehlers-Danlos syndrome is a deficiency in _
Vascular Ehlers-Danlos syndrome is a deficiency in type III collagen
* Blood vessel aneurysms, organ rupture
Classical Ehlers-Danlos syndrome is a deficiency in _
Classical Ehlers-Danlos syndrome is a deficiency in type V collagen
* Hyperextensible skin, hypermobile joints, joint dislocation, tendency to bleed, easy bruising
A patient presents with history of organ rupture and easy bruising; they may have _
A patient presents with history of organ rupture and easy bruising; they may have vascular EDS (problem with type III collagen)
A patient presents with hyperextensible skin, tendency to bleed, and joint dislocation; they may have _
A patient presents with hyperextensible skin, tendency to bleed, and joint dislocation; they may have classical EDS (issue with type V collagen)
What is the secretory mechanism of eccrine sweat glands?
Exocytosis or merocrine
Characterize the secretions from eccrine sweat glands
Eccrine sweat glands secrete mucinogen-rich product and watery electrolyte-rich material
Characterize the secretions from apocrine sweat glands
Apocrine sweat glands secrete viscous secretions onto hair follicles where the bacteria acts –> odor
Sweat glands are under sympathetic control and are (cholinergic/ adrenergic)
Sweat glands are under sympathetic control and are cholinergic
Papillary dermis (left)
Reticular dermis (right)
What type of gland are the sweat glands?
Sweat glands are simple coiled tubular glands
What type of glands are sebaceous glands?
Sebaceous glands are branched acinar glands
* The duct empties into the neck of a hair follicle
Sweat glands are found in _ layer of the skin
Sweat glands are found in reticular dermis layer of the skin
Sebaceous glands are found in the _ layer of the skin
Sebaceous glands are found in the reticular dermis layer of the skin
_ is a smooth muscle that elevates the hair and is sympathetically innervated
Arrector pili muscle is a smooth muscle that elevates the hair and is sympathetically innervated
Apocrine gland
Sebaceous gland
What is the function of the following?
Meissner corpuscle: function in fine touch perception
* Dermal papillae of thick skin, eyelids, nipples
What is the function of the following?
Pacinian corpuscles are found deep in the dermis/hypodermis and they are especially abundant in the breasts and digits
* They percieve pressure, touch, vibration
Where do we find the following?
We find free nerve endings around hair follicles and in the trachea in the dermis layer
* Function in sensing pain, heat, touch
* Free Nerve endings = Fire (heat) and Nocioception (heat)
What is the function of the following?
Merkel disks provide information on pressure, position, and static touch (recognizing shapes and edges)
* Located in the epidermis near follicles
Ruffini’s endings sense _
Ruffini’s endings sense pressure and touch
* Found in the dermis and joints
Which disease might be associated?
Scurvy- corkscrew hair
* Other signs: bleeding gums, tooth loss, bruising and poor wound healing, weakened immune response, thin appearance
* Administer vitamin C
Bone has _ collagen
Bone has type I collagen
Dentin has _ collagen
Dentin has type I collagen
Ligaments have _ collagen
Ligaments have type I collagen
Dermal-epidermal junction has _ collagen
Dermal-epidermal junction has have type V collagen
Bone marrow has _ collagen
Bone marrow has have type III collagen
Basal lamina of the basement membrane has _ collagen
Basal lamina has have type IV collagen
Organ capsules have _ collagen
Organ capsules have have type I collagen
The vitreous body has type _ collagen
Vitreous body has have type II collagen
The cornea of the eye has _ collagen
Cornea has have type I collagen
Hyaline cartilage, elastic cartilage, and fibrocartilage have _ collagen
Hyaline cartilage, elastic cartilage, and fibrocartilage have type II collagen
The nucleus pulposus has _ collagen
The nucleus pulposus has type II collagen
Smooth muscle cells have _ collagen
Smooth muscle cells have type III collagen
Elastic fibers are composed of _ and _
Elastic fibers are composed of elastin and fibrillin
* These get synthesized by fibroblasts, smooth muscle cells, chondrocytes/chondroblasts
What is the following?
Elastic fibers
Steps of collagen synthesis
- Collagen mRNA is made in the nucleus –> travels to the rough ER
- Pre-procollagen (alpha chains) gets created
- Hydroxylation of Pro (P) and Lys (K) Must have Vitamin C as cofactor for hydroxylation; lacking vitamin C = scurvy
- Glycosylation of hydroxylysines
- Procollagen triple-helix forms (3 alpha-chains align and coil)
- Carbohydrates get added
- Secretion is by exocytosis
Out of the cell:
1. Procollagen is cleaved into tropocollagen
2. Tropocollagen assembles into collagen fibrils (cross-linking)
Defects in these extracellular events can lead to EDS
Swollen gums, poor wound healing, bruising can be signs of _
Scurvy!
* Decreased hydroxylation of pro and lys
* Decreased collagen synthesis and weak collagen
Defects in formation of the triple helix of procollagen can result in _
Osteogenesis imperfecta!
Decreased formation of procollagen:
* Multiple fractures in childhood
* Blue sclerae
* Hearing loss (ossicles of ear)
* Abnormal teeth (lack of dentin)
Osteogenesis imperfecta is a decrease in type _ collagen and results due to a defect in _ formation
Osteogenesis imperfecta is a decrease in Type I collagen and results due to a defect in procollagen (triple helix) formation
Ehlers-Danlos syndrome is a genetic disease that results from a defect in type _ or type _ collagen
EDS: defect in type III or type V
Type III: aneurysms of various vessels, organ rupture
Type V: hyperextensible skin, hypermobile joints, joint dislocation, tendency to bleed, bruising (epidermal-dermal junction)
What happens if we have a defect in type IV collagen?
Type IV collagen is found in the basement membrane
* Alport syndrome: kidneys, hearing, eyes affected; “can’t see, can’t pee, can’t hear a bee”
* Goodpasture syndrome: pulmonary alveoli, renal
A patient has impaired kidney function, hearing loss, and eye problems; they may have _
A patient has impaired kidney function, hearing loss, and eye problems; they may have Alport syndrome
* “Can’t see, can’t pee, can’t hear a bee”
* Defect in type IV collagen
Marfan syndrome results from mutations in genes encoding _
Marfan syndrome results from mutations in genes encoding fibrillin which is important part of elastic fibers
* Long, slender limbs and fingers
* Lens of eye dislocated
* Cardiovascular problems (aorta rupture)
How can we identify pericytes?
Pericytes support capillaries; they sit on the capillaries; look for endothelial cells
Is this a resident or transient cell of the connective tissue?
Mast cell- resident
Is this a resident or transient cell of the connective tissue?
Macrophage- transient
These cell types are (transient/ resident) cells of connective tissue
These cell types are transient cells of connective tissue (leukocytes)
Differentiate between connective tissue from mesenchymal stem cells vs. hematopoietic stem cells
Mesenchymal:
* condroblasts –> chondrocytes
* adipocytes
* fibroblasts
* mesothelial cells
* endothelial cells
* osteoblast –> osteocyte
Hematopoietic:
* macrophage
* osteoclast
* mast
* neutrophil
* etc
What is the function of this cell?
Fibroblast product procollagen and ECM components; aid in wound healing
* Active –> spindle/ fusiform
What role do fibroblasts play in wound healing?
Fibroblasts migrate across blood clots where they adhere to fibronectin (a glycoprotein in ground substance)
The following cells have what function?
White adipose tissue: “unilocular fat”
* Synthesis and storage (TG) of fat
* Rich neurovascular supply
* Cytoplasm and nucleus squeezed to periphery
What gives this cell its brown color?
Mitochondria!
* UCP1: uncoupling protein 1 allows proton movement to get converted to heat instead of ATP
Brown fat is multilobular
Dense regular connective tissue is found in _ areas of the body and made of _ collagen
Dense regular connective tissue is found in tendons, ligaments areas of the body and made of type I collagen
Dense irregular connective tissue is found in _ areas of the body and made of _ collagen
Dense irregular connective tissue is found in skin, organ capsule areas of the body and made of type I collagen
Reticular connective tissue proper is found in _ areas of the body and has _ collagen
Reticular connective tissue proper is found in bone marrow, lymph nodes, spleen areas of the body and has type III collagen
Where do we find loose, areolar connective tissue?
Supporting tissue & lamina propria
What is this cell’s function?
Mesenchyme- stem cells can differentiate into fibroblasts, osteoblasts, endothelial cells, adipocytes, chondroblasts
The endomysium and perimysium surround what?
Endomysium: surrounds cells (myofibers)
Perimysium: surrounds fasciles (bundles)
Epimysium: surrounds entire muscle; forms aponeuroses and tendons
Epimysium
Perimysium
Endomysium
Muscle
Fasicle
Cell
Myofibril
Myofilament
What would happen if we didn’t have the structure marked T in some muscle fibers?
Lacking T-tubules = uncoordinated contraction of myofibrils
What is seen in the periphery of cell 1 and cell 2? Purple
Nucleus
Which bands shorten during muscle contraction?
H and I bands
What is the dark band in the middle?
A band
