Histology Etc. Flashcards
Function of collagen, elastin, reticular fibers:
Collagen: resist tension.
Elastin: allow for stretching.
Reticular fibers: form supportive meshwork.
Scurvy
Vit C deficiency leading to UN-linked collagen.
Ehlers-Danlos syndrome
Abnormal collagen synthesis leading to weak collagen.
Marfan’s syndrome
Mutation in fibrillin-I, a component on elastin fibers. Targets CVS, skeletal oculars, etc.
Main players in the ECM of CT (4)
Proteoglycans
Hyaluranon
Glycoproteins
EC proenzymes
Embryonic CT
Rich in ECM and MSCs. Little collagen or reticular fibers.
Function of LACT
Support and bind tissues, hold body fluids, defends against infection.
Found beneath epithelia, BVs, muscles, nerves.
Function of Reticular CT
To hold free cells.
Found in liver, bone marrow, lymph nodes, etc.
Dense irregular CT overview
Fibroblasts main cell type.
Resists tearing.
Found in dermis, organ capsules, perichondrium/periosteum, fascia.
Dense regular CT overview
Fibroblasts main cell type.
Resists pulling.
Poorly vascularized.
Found in tendons, ligaments, aponeuroses, joint capsules.
Where is elastic CT found?
BV walls, bronchioles, special ligaments.
Fibroblasts produce:
Collagen, elastin, RFs, proteoglycans, glycoproteins.
Hyaline cartilage overview
Has a perichondrium.
Type II collagen.
Articular cartilage, larynx, trachea, embryonic development.
Elastic cartilage overview
Has a perichondrium.
Type II collagen.
External ear, epiglottis, auditory tube.
Hyaline + elastin.
Fibrocartilage
No perichondrium.
Type I collagen.
IV disks, pubic symphysis, TMj.
Hyaline + dense regular CT.
Articular cartilage is __________ and lacks a __________:
Hyaline, perichondrium.
Territorial and interterritorial matrix
TM has less collagen and more GAGs than ITM.
Perichondrium overview
Has blood supply.
Source of new cartilage.
Has 2 layers: fibrous, chondrogenic.
Fibrous layer of perichondrium
Outer layer that produces type I collagen and elastin.
Chondrogenic layer of perichondrium
Inner layer that differentiates into chondroblasts.
Secretes type II cartilage.
Appositional growth overview
Cartilage formed on existing cartilage.
Undifferentiated cells –> chondroblasts –> secrete type II collagen and ground substance.
Interstitial growth overview
Takes place within cartilage mass.
Chondrocytes divide in lacunae, forming new isogenous groups.
Increases in mass but is limited due to avascular nature.
Zones of articular cartilage (4) superficial to deep:
Superficial zone
Intermediate zone
Deep zone
Calcified zone
Layers of epidermis
Stratum corneum Stratum lucidem Stratum granulosum Stratum spinosum Stratum basale
Epidermis is comprised of (4):
Keratinocytes
Melanocytes
Merkel cells
Langerhans cells
Strattum basale
Single layer of keratinocytes
Contains melanin.
Stratum spinosum
Several layers thick.
Has spiny processes.
Can produce corns/callouses.
Stratum granulosum
Thickest layer of non keratinized portion.
Contains granules that assemble keratin into bundles.
Irregularly shaped and variable in size.
Stratum corneum
Anucleated cells.
Filled with keratin.
Forms water barrier.
Keratinocytes
Most prominent cell.
Participate in epidermial water barrier.
Basal cells
Synthesize keratin and group the into tonofibrils.
Spinous cells
Keratin synthess continues and granules begin to bundle keratin and produce lamellar bodies.
Granular cells
Discharge lamellar bodies.
Continue to promote bundling of keratin via flaggrin.
Cells now cornified.
Melanin production
Premelanosomes begin producing melanin, then become melanosomes. Melanin transferred to keratinocytes via pigment donation.
Langerhans cells
APCs that are monocyte precursors.
Identifyable in the stratum spinosum.
Merkel cells
Function in cutaneous sensation.
Found in stratum basale and associated w/ nerve endings.
Layers of dermis (2)
Papillary layer
Reticular layer
Papillary layer has:
Collagen and elastic fibers.
Vaculature and nerve endings.
Reticular layer is:
Irregular. Has type I collagen and elastic fibers. Forms Langerhans lines.
Meissner’s corpusle
Low frequency touch receptors.
Found in dermal papillae.
Pacinian corpuscle
Detects pressure/vibration.
Found deep in dermis.
Free nerve endings terminate in the:
Stratum granulosum.
Lack CT.
Sebaceous glands
Produce sebum. Found alongside hair follicles.
Eccrine sweat glands
Coiled and widespread.
Cholinergic activation.
Apocrine sweat glands
Axilla, genitals, nipple, anus.
Adrenergic activation.
Uses merocrine secretion.
Merocrine vs apocrine
Merocrine is in vescles.
Apocrine is a portion of cytoplsm being pinched off.
