EXAM III Material Flashcards
What are the different forms of immunity? (6)
Innate Immunity - inflammation, neutrophils
Acquired Immunity
Passive Immunity - temporary (transfer to fetus)
Active Immunity
Cell-mediated Immunity
Humoral Immunity
What are the primary lymphoid organs?
Thymus
Bone marrow
What are the secondary lymphoid organs?
Lymph Nodes
Spleen
Tonsils
Trapped Ag stimulate clonal expansions of mature T and B cells
Characteristics of Lymph follicles and types
Are not Enclosed within a capsule (Lymph Nodes ARE)
Singly or in aggregates
Sites of B cell localization & proliferation
Transient
Primary (unexposed) and Seconday (exposed) follicles
Characteristics of Primary follicles (nodules)
Spherical
Tightly packed accumulations of virgin B cells and dendritic reticular cells that haven’t been exposed to Ag
Characteristics of secondary follicles (nodules) and structure
Derived from primary follicles that have been exposed to foreign Ag
Not present at birth
Contain a Corona (cortex) - dark peripheral region, w/ densly packed B lymphocytes
and Germinal center - central, light, w/ B lymphocytes, memory B cells, plasma cells, dendritic reticular cells = Ag-presenting cells
Components of Diffuse lymphoid tissue
Subcutaneous-associated lymphoid tissue = papillary layer of dermis
Lamina propria-associated lymphoid tissue =
BALT - bronchial-associated lymphoid tissue
GALT - gut-associated lymphoid tissue
MALT - mucosal-associated lymphoid tissue
What is Lymphopoiesis?
Generation of lymphocytes
All originate in bone marrow
Immature T cells travel to thymus
B-cells travel to regions in lymphoid tissue
What are the surface receptors during maturation of B cells?
IgM and IgD
MHC Class II
Complement receptors
Ig Fc receptors
What is the function of MHC, where are they expressed and what recognizes them?
The presentation of (foreign) antigenic peptides of T cells
MHC I - surface of all cells except trophoblast & RBCs
via CD8+
MHC II - surface of B cells & Ag-presenting cells
via CD4+ on surface of APCs
Characteristics of CD4+ T cells
Recognize Ag on MHC II molecules
Helper Cells: assist CD8+ cell and B cell differentiation
Characteristics of CD8+ T cells
Cytolytic T cells; recognize Ag bound to MHC I molecules
Undergo mitosis
Release: perforins (punch holes in cells) and Fas ligand (signaling pathway for apoptosis of infected cells)
Mediators of cellular immunity
What are the characteristics of CD16+ T cells and what cytokines do they release? (5)
NK T cells
Interleukin-2 - stimulates NK cell proliferation
Interferon-ý - activates NK cells
Macrophage activating factor (MAF)
Chemotactic factors
Tumor necrosis factor (TNF-beta) - directly kills tumor cells
Define Parenchyma
Part of lymph node that contains cells that typically pack areas of lymphoid organ:
Mostly lymphocytes
Define Stroma
Part of lymph node that consists mainly of reticular fibers and cells; such as undifferentiated cells and fixed and free MOs
What are other histological structures of lymph nodes?
Hilus - entry & exit point for vessels (efferent enter thru hilus, afferent enter convex side)
Capsule - dense collagen fibers, some elastic fibers & smooth muscle fibers
Trabeculae - extensions of capsule
Cortex - (outer, follicles, deep/inner
Medulla
Components of Cortex of lymph nodes?
Outer - B cell zone - contains lymph follicles/nodules
Follicles - contain B cells, follicular & migrating dendritic cells
Secondary - mantle, germinal layer
Primary - lack both mantle and germinal layer
Deep/Inner Cortex - T cell zone -contains TH cells, MOs, High endothelial venules (HEVs) - port of entry for circulating differentiated lymphocytes to seed lymph node
What are the medulla characteristics of lymph nodes?
Irregular arrangment of loose medullary sinuses & dense medullary cords
(sinuses lined w/ MOs, cords contain blood vessels, lymphoblasts & plasma cells)
Site of lymphocyte reentry into lymph stream
Thymic-dependent areas in subcortical & deeper medullary regions
What are the components of the thymus?
Capsule
Trabeculae/Septa
Lobules
What are the characterisitcs of capsule of the thymus?
Contains blood vessels and efferent lymphatics
NO afferent lymphatics (lymph cells cannot enter via lymphatic system)
Extends trabeculae (septa) into the parenchyma
Characteristics of trabeculae (septa) of the thymus?
Contain delicate CT
Divides the thymus into incomplete lobules
Characteristics of Lobules of the Thymus?
Outer, Darker staining Cortex
Contains Epithelial reticular cells that secrete thymosin (a cytokine involved in early T cell differentiation & migrate to medullary areas) and T cells in various stages of diff., blood vessels for maintenance of lymphopoiesis
Inner, lighter staining Medulla
Allows entry channel into blood stream of mature lymphocytes
Hassall’s corpuscles - whorls of highly keratinized medullary epithelial cells that produce cytokine thymic stromal lymphopoietin = stimulates thymic dendritic cells needed for single (+) T cell maturation
Characteristics of the thymus? When are they fully developed? What is absent in their structure?
Most developed at puberty; 10-15g at birth, 30-40g at puberty
Involutes during adolescence
No lymph follicles (nodules; B cells)
No afferent lymph vessels
No lymph sinuses
What are the types of T cells involved during T cell differentiation?
Double (-) T cells - lack cell surface molecules, enter cortex from blood vessels, proliferate in subscapular area
Double (+) T cells - move to outer cortex, express CD4 & CD8 & TCR, interact w/ epithelial cells w/ MHC I & II for clonal selection,
Single (+) T cells - move to inner cortex, express TCR and EITHER CD4 or CD8
Medulla = clonal deletion completed (copies of T cells)
What is the blood-thymus barrier and where is it located?
Thymic cortex
Prevents Ag in the blood from reaching developing T cells in thymic cortex
Leaky during fetal life to allow for development of immunologic tolerance to self-Ag
Describe spleen morphology
No lymph sinuses
No afferent lymph vessels
Covered by peritoneum except at hilus
Blood vessels enter and exit hilus
Divided into red and white pulp
Mesothelium-lined CT capsule contains some smooth muscle fibers & sends trabeculae into parenchyma
What are the functions of the spleen?
Blood filtering functions:
Only lymphatic organ specialized to filter blood
Stores and removes worn out RBCs
Recycles iron
Converts Hb to bilirubin
in fetus = blood formation
Immunologic functions:
Screens foreign material in blood
Produces lymphocytes & plasma cells
Removal leads to overwhelming bacterial infections in infants, children, & young adults
Features of white pulp of the spleen
Elongated, branched strands, Associated with arteries, center & off center; germinal centers & diffuse lymphoid tissue
Site of clonal expansion of Ag-stimulated lymphocytes
Off center central arteriole of secondary follicles = B cell area
Center arteriole contains T cells = forms periarterial lymphatic sheath (PALS)
Reticular fibers w/ fixed MOs & support splenic pulp
Describe marginal zone histology of the spleen
Forms sinusoidal interface b/w red pulp and white pulp
Many Ag-presenting cells where lymphocytes have first Ag encounter and activated TH cells activate B cells
Describe red pulp histology of the spleen
Surrounds white pulp (majority of spleen; 80%)
Function = Filter blood (hence it’s red pulp)
Many RBCs
Billroth cords = red pulp parenchyma
w/ blood cells, plasma cells, Ag-presenting cells, Terminal capillaries open directly into substance of cords (open circulation), MO destroy worn-out, defective RBCs
Venous sinusoids - storage site for healthy RBCs, discontinuous basement membrane
What does the white pulp of the spleen consist of?
Central arteriole
PALS (pariarteriolar lymphoid sheath)
Corona formed by B & Ag-presenting cells
Germinal center
What is the red pulp formed by in the spleen?
Penicillar arteriole
MO-sheathed capillaries
Splenic sinusoids
Reticular cells = stroma (cords of Billroth)
all cell types of the circulating blood
Describe the characteristics of the tunica media
Components:
Smooth muscle cells and fibroblasts
Collagen and elastic fibers
Describe the characteristics of the tunica adventitia
NOT present in arterioles
Components:
Loose areolar tissue, irregular fibroelastic tissue w/ adipocytes, vasa vasorum and nervi vasorum (nerves)
Outermost layer
Define Pericytes
Undifferentiated mesenchymal cells
May be contractile, may serve as stem cells to differentiate into fibroblasts, etc.
List the general organization of the skin (5)
Epidermis
Basement Membrane
Dermis - (corresponds to lamina propria of a mucous membrane)
Subcutaneous/Hypodermis tissue
Epidermal ridges
What are the layers of the epidermal ridges and how are they formed? (4)
Primary dermal ridge - 3rd-4th months fetal life, subdivided into two secondary dermal ridges by interpapillary peg. Everywhere except foreheard, external ear, perineum & scrotum
Interpapillary peg - downward growth of epidermis along crest
Secondary dermal ridge - branched, double rows. Thin collagenous, reticular, and elastic fibers
Dermal papillae - upward projections from each secondary dermal ridge
List some of the integumentary functions
Protection from mechanical injury
Prevents dessicaiton
Protects against foreign substances & microorganims
Protects against UV radiation
Thermoregulation
Regulation of BP
Excretion of metabolic waste products
Synthesis of provitamin D
Is it possible for subcutaneous/hypodermis or dermis layer to have both thin and thick skin?
NO
Only epidermis contain thick and thin skin
Where is thick skin located
Palms & soles
~0.4-0.6 mm thick
Displays all 5 epidermal layers
Where is thin skin and what are some characteristics?
Located all over the body besides the palms & soles
~75-150 um thick
Thinnest = eyelids
Thickest = back
Thicker on extensor surfaces than flexor surfaces
Epidermal layers less distinct & lack stratum lucidum
List the layers of the epidermis from deep to outermost
BSGLC Big Skinned Girls Love Cheesecake
Stratum basale/germinativum
Stratum spinosum
Stratum granulosum
Stratum lucidum - absent in thin skin
Stratum corneum
Which epidermal layers are within the stratum Malpighi? (2)
Two deepest:
Stratum basale
Stratum spinosum
Which epidermal layer is absent in thin skin?
Stratum lucidum
What are Merkel cells?
What are the purpose of Merkel cells?
Primary locations?
Tactile mechanoreceptors
May also act as diffuse neuroendocrine cells
Usually in stratum germinativum/basale
Contain catecholamine-like granules
Palmar and plantar epidermis
Derived from neural crest
Associated with basal lamina
What is the purpose of Langerhans cells and where are the located?
Stratum of Malpighi (basale & spinosum)
Derived from bone marrow precursor
Peripheral dendritic cell of immune system = APCs in lymph node (migrate there)
Primarily in stratum spinosum
Dendritic cells
Birbeck granules
Where are melanocytes derived from and where are they located?
Neural crest; derived from melanoblasts
Does not form desmosomes attachments in epidermis
Inject melanin granules into keratinocytes
First cells to arrive in the epidermis
Cell body is in the stratum basale w/ cytoplasmic extensions on keratinocytes = epidermal-melanin unit
Melanin formation pathway requires Tyrosinase
What are the characteristics of stratum basale (germinativum)?
Deepest
Columnar to high cuboidal keratinocytes
Keratins 5 and 14 = major products of basal keratinocytes
Single layer of cells - held together via desmosomes, hemidesmosomes hold layer to basal lamina
High mitotic activity - producing stem cells differentiating keratinocytes, affected by chemotherapeutic & radiation treatments
What are the characteristics of the stratum spinosum
Polyhedral-shaped cells (prickle cells)
Keratins 1 and 10 (high molecular weight) replace 5 & 14 when basal keratinocytes migrate to spinosum
Keratohyalin granules develop
Contain primarily Langerhans cells
Membrane-coating granules first appear - lamellar bodies containing lipid, carbs, & hydrolytic enzymes
Tonofibrils - form intercellular bridges (adherin-type junctions)
What are the characteristics of stratum granulosum?
Multilayered
Keratins 2e and 9
Flattened nucleated keratinocytes
Keratohyalin aggregates - fillagrin (nonintermediate filament protein) induces cross-linkage of keratin filaments by disulfide bonds = keratin aggregation, no limiting membrane
Membrane-coating granules (lamellar bodies)
Tonofilaments
List characteristics of stratum lucidum
Clear layer/no detail
Flat keratinocytes lacking nuclei and organelles
Only found in thick skin
Contains eleiden
Which skin layer is only present in the thick skin?
Stratum lucidum
List characteristics of stratum cornuem
Multilayered
Thicker in thick skin
Enucleated, flattened, dead keratinocytes
Cytoplasm replaced by keratin
Cytoplasm contains: keratin cross-linked with filaggrin which produces cornified cell envelope
What are some characteristics of the dermis layer?
Derived from?
Function?
Dense fibrous irregular CT layer beneath epidermis
Derived from embryonic mesoderm
Induces development of epidermis and epidermal derivatives
Supports epidermis
Describe some hypodermis characteristics
Loose CT that underlies dermis
Corresponds to superficial fascia of gross anatomy
Technically not part of skin
May contain fat cells that can form a thick layer = panniculus adiposus
2 layers = papillary and reticular layer
What are the components of the two layers of the dermis?
Papillary layer (closest to epidermis)
Loose CT, separated from epidermis by basal lamina, network of fine elastic fibers and abundant capillaries
Reticular layer
Dense irregular CT
Fibrocytes, MOs, adipocytes
What is the role of IgA and where are they secreted from?
Produced by GALT (secretory IgA, sIgA)
Prevents microorganism binding to epithelium by coating microorganisms
Does not stimulate complement system
Synthesized & secreted by plasma cells in lamina propira of gut
Picked up at the basal surface of enterocytes & transported across the cell
secretory component inhibits degradation of sIgA by proteolytic enzymes in GI lumen while in the cell
List characteristics of acquired immunity
Develops in response to Ags
More powerful than innate immunity
Takes longer to develop
Displays specificity and memory
Where in the body do precursor cells mature into immunocompetent cells and are programmed to recognize a specific Ag?
In the primary lymph organs
i.e. thymus and bone marrow
Where in the body do trapped Ags stimulate clonal expansions of mature T and B cells?
Secondary lymphoid organs
i.e. spleen, lymph nodes, tonsils
Where in the body can you find B cells and dendritic reticular cells that have not been exposed to Ags?
Primary follicles/nodules
Where in the body can you find cells that have been exposed to nonself Ags? These are not present at birth
Secondary follicles/nodules
What are the components of the small intestine?
Duodenum
Jejunum
Ileum
What are the layers of the intestinal wall? (4)
M.S.M.S.
Mucosa w/ lamina propria and muscularis mucosa
Submucosa
Muscularis layers
Serosa
What are some characteristics of the duodenum?
Villi with a “leaflike” shape
Crypts of Lieberkuhn
Brunner’s glands (mucous-secreting) in the submucosa
What are some characteristics of the jejunum?
Finger-like villi; longer and more narrow
Crypts of Lieberkuhn
No glands in submucosa (as opposed to duodenum; Brunner’s glands)
What are some characteristics of the Ileum?
Shorter villi (compared with jejunum)
M cells (Ag-transporting cells; b/w villi in pits)
Peyer’s patches (lymphoid aggregates = large follicles) thruout lamina propria and submucosa
Crypts of Lieberkuhn
No glands in submucosa
What type of epithelium is within the large intestine?
Simple columnar with crypts but no villi
What are the cells of the crypts of Lieberkuhn? (4)
Enterocytes
Enteroendocrine cells
Goblet cells
Paneth cells
What are crypts of Lieberkuhn and where are they found?
Simple tubular glands within the intestinal mucosa of the duodenum and jejunum
Open b/w adjacent villi and extend to muscularis mucosa
What are enterocytes, where are they located and what is their function?
Located in the crypts of Lieberkuhn
Columnar epi. cells w/ a basal nucleus, perinuclear Golgi and apical brush border
Produce disaccharides, absorb proteins, carbs, lipids
Enzymes on apical brush border are involved in carb digestion
Produce enteropeptidase/enterokinase for activation of pancreatic zymogens & proenxymes
What are Paneth cells, where are they located and what are their functions?
Cells of the crypts of Lieberkuhn
Basal crypt cells; found at base of mucosal glands
Prominent eosinophilic granules
Produce lysozyme to control intestinal flora; increases permeability of bacteria by degrading peptidoglycan
Defensins increase membrane permeability of target organisms
Tumor necrosis factor-alpha (proinflammatory cytokine)
May phagocytize some microorganisms and help regulate intestinal flora
What are enteroendocrine cells, where are they located, and what is their funciton?
Cells of the crypts of Lierberkuhn
Produce peptide hormones & serotonin; may produce paracrine or autocrine secretions
Stain w/ chromiun/chromaffin; respond to silver stains = agyrophilic
Analogous to unicellular goblet cells
Formed from endodermal stem cells in GI tract
What are Brunner Glands and where are they located? What is their function?
Glands in the submucosa of duodenum
Form bicarbonate and mucus which supplements bicarbonate from the pancreas
Necessary to neutralize gastric acid
What are Peyer’s patches? Where are the located? What is their function?
Dome-shaped lymphoid structures under mucosal surface; Ileum
Contain HEVs = entrance of lymphocytes into lymphoid organs from bloodstream
Mucosal coverings contain M cells
Contain B- and T- cell dependent areas
What are the functions of the large intestine? (5)
Absorption of fluid
Continuation of digestion initiated in small intestine
Formation of fecal mass
Goblet cell = prominent cell
Secretion of mucus for lubrication
What is a major feature of the GI tract that provides a defense mechanism for the segments?
Epithelial cells are held together by occluding junctions held together via transmembrane proteins claudins and occludins
Function to prevent paracellular transport
Otherwise, Ag may reach the lamina propria
What is rapid cell turnover and explain how it works in the esophagus & anus, small intestine, large intestine, and stomach
Protective mechanism by GI epithelium; lining replaced every 5 days
Esophagus & Anus - new cells in basal layer of stratified epithelium & migrate thru sub-basal levels to be sloughed off into lumen
Small Intestine - new cells formed in crypts from undifferentiated cells
Large Intestine - located at base of cypts due to no villi
Stomach - stem cells = neck of gastric glands
Differentiate into surface & neck mucus cells, enteroendocrine cells, parital cells, chief cells
What are the cellular characteristics of Paneth cells?
Basophilic basal cytoplasm
Supranuclear Golgi complex
Large, intensely acidophilic apical secretory granules
Describe the mucosal layer of the GI tract. Location? Secreted by? Made up of?
Coats intestinal epithelial luminal surface
Secreted by goblet cells
2 layers: Outer = microorganisms
Inner = antimicrobial proteins (from paneth cells, enterocytes, goblet cells) that resist microbial penetration
What are toll-like receptors? What are their functions?
A type of pattern recognition receptor
Located on the surface of enterocytes
Recognize structurally conserved molecules that are broadly shared by pathogens, but they are distinguishable from host molecules
Pathogen associated molecular patterns (PAMPs)
Once Ag binds; B-cell is produced and matures into plasma cells then Abs in lamina propria
What are M cells, what is their function?
Microfold cells
Involved in the initiation of the immune response
Take up Ag which bind to Ig receptors on lymphocytes surface, transferring them to dendritic cells; APCs (in the underlying lamina propria) = T cells
What are GALTs? Where are they located and what are they composed of?
Gut-Associated Lymphoid Tissue
Appendix, Peyer’s patches, Mesenteric lymph nodes
Transitory aggregations of lymphocytes, neutrophils, and eosinophils
Bulk of body’s immune system located here
Produces IgA
Where does carbohydrate digestion begin?
In the mouth via enzyme amylase
What is the role of amylase?
Hydrolyzes starch to form sugars; disaccharides
Amylase is secreted via pancreas
Where are disaccharides broken down to monosaccharides? Where are monosaccharides absorbed? How?
Brush border of small intestine
Monosaccharides absorbed via enterocytes via Na+-dependent sugar glucose transporter-1 (SGLT-1)
What are the 3 events involved in protein digestion? What are the locations?
Proteins –> Peptides (stomach)
Polypeptides –> Peptides (small intestine)
Oligopeptides –> Amino Acids (Intestinal brush border)
What enzyme is involved in protein digestion in the mouth?
Pepsine
In the stomach’s acidic environment
What enzyme(s) are involved in protein digestion in the stomach (4)? What is happening? Where?
Breakdown of polypeptides –> proteins (small intestine)
Pancreatic Enzymes: (4)
Trypsin
Chymotrypsin
Elastase
Carboxypeptidase
What enzyme activates pancreatic enzymes that are involved in the breakdown of polypeptides to peptides in the small intestine?
Enteropeptidase/Enterokinase
via duodenal enterocytes
Where does the breakdown of oligopeptides to amino acids occur?
Bursh border of the intestine
The transport of aa into enterocytes is via a carrier-mediated process
Where does lipid digestion begin?
Small intestine
What is the role of pancreatic lipase in lipid digestion?
Emulsifies triglyceride droplets that enter the small intestine into smaller droplets releasing FAs and glycerol
FAs and glycerol combine with bile salts to form micelles
What is a micelle and what is its role in lipid digestion?
Micelles arise from glycerol and FAs that combine with bile salts
Micelles transport:
FAs
Monoglycerides
Glycerol
Phospholipids
Cholesterol
Vit A and K
Micelles are passively absorbed across enterocyte apical plasma membrane via FABPs (FA Binding protein)
What is the role of pancreatic lipid esterase?
Splits cholesterol esters into cholesterol and FAs
What are the steps necessary during differentiation of T cells? (4)
Double negative
Double positive
Single positive
Clonal deletion
What are the characteristics of double negative T cells? Where are they located?
Lack cell surface molecules (in mature T cells)
Proliferate in subcapsular area (outside cortex)
Enter cortex from blood vessels
What are the characteristics of double positive T cells and what do they express?
Express both CD4 & CD8 coreceptors and TCR receptors
Are deeper in cortex
Confronted with epithelial cells w/ cell surface MHC classes I and II for clonal selection
What do single positive T cells express?
Either CD4 or CD8 and TCR receptors
Mature T cells
Where does clonal deletion of T cells occur?
Medulla
What are the components of the blood thymic barrier? (6)
Endothelium
Endothelial basal lamina
Perivascular space
Reticular cells
Basal lamina of reticular cells
Thymic parenchymal cells
What are the blood filtering functions of the spleen?
Blood filtering functions:
Only lymphatic organ specialized to filter blood
Stores and removes worn out RBCs
Recycles iron
Converts Hb to bilirubin
in fetus = blood formation
What are the immunologic functions of the spleen?
Immunologic functions:
Screens foreign material in blood
Produces lymphocytes & plasma cells
Removal leads to overwhelming bacterial infections in infants, children, & young adults
What occurs in the white pulp of the spleen?
Clonal expansion of Ag-stimulated lymphocytes
What forms the periarterial lymphatic sheath (PALS) of the spleen?
T cells that are contained in the areas surrounding the central artery near the center of the white pulp
What is the function of the marginal zone of the spleen?
Forms sinusoidal interface between red pulp and white pulp
The site of initial Ag exposure to lymphocytes
Which gland cells are stimulated at puberty?
Sebaceous glands
Sudoriferous/sweat Apocrine glands
What is the function of the red pulp of the spleen?
Filters blood
What are the 3 arteries of the spleen?
Splenic artery - enters hilus
Trabecular artery - branches off
Central artery - where adventitia loosens and becomes mesh-like reticulum infiltrated with lymphocytes. A penicillus is formed when capillaries enter red pulp
Cappillaries - supply white pulp
What are the components of the penicillus of the spleen?
Pulp arteriole
Sheathed arteriole
Terminal capillary - drains into intercellular/open spaces or venous sinuses lined w/ reticuloendothelial cells/closed system
What are Langerhan cells?
Were are the derived from and what are their functions?
Dendritic cells; via monocytes
Ag-presenting cells (APC cells)
Primarily in stratum spinosum; migrate from epidermis to lymph nodes
Birbeck granules
List the cells of the skin (4)
Keratinocytes
Langerhans cells
Merkel cells
Melanocytes
What type of glands are sebaceous glands? (Apocrine, Holocrine, Merocrine, etc.)
Holocrine glands
Secretions are released by destroying cell membrane of sebum-producing cells
Where are sebaceous glands found on the body?
Everywhere besides palms and soles of the feet
What is the structure of sebaceous glands and what do they produce? When is the growth of these glands stimulated?
Branched acinar glands w/ short ducts
Produce sebum continuously; released into hair follicle
Growth stimulated at puberty by sex hormones
What are sudoriferous glands? What type of glands are they?
Sweat glands
Merocrine glands & Apocrine glands
What are characteristics of sudoriferous glands?
(sweat glands)
Duct system with stratified cuboidal epithelium except in epidermis
Cholinergic endings; stimulated by ACh
What are characteristics of merocrine glands (apart of sudoriferous glands)
Coiled, simple tubular secretory portions
Lined by simple epithelium
Apical dark secretory cells secrete glycoproteins
Basal clear cells secrete water and electrolytes
Myoepithelial cells
What are characteristics of apocrine glands (apart of sudoriferous glands)?
Location?
Structure?
Found in labia majora, areola, axillary & anal regions
Thicker, more viscous secretions than merocrine types
Excretory duct opens into hair follicle
Adrenergic innervation
Inactive until pubery
Special types; ceruminous glands, glands of moll
What are the special types of apocrine glands of the sudoriferous glands?
Ceruminous glands (ear canal, ear wax)
Gands of Moll (eyelids; keeping them from sticking together)
What are the components of the hair follicle?
Root (the growing part of the hair)
Free shaft
Hair follicle
Which embryonic layer is the hair follicle derived from?
Epidermis
Developed as elastic, keratinized threads
What are the components of the hair follicle? (3)
Sebaceous glands, arrector mili muscles
Hair bulb
External root sheath - down growth of epidermis
Internal root sheath - generated by bulb matrix
What are the 2 components of the hair bulb and where is it in relation to the hair follicle?
Matrix and vascularized dermal papilla
Located at the lower part of the hair follicle
What are the layers of the internal root sheath of the hair follicle? CHH
CHH
Cuticle - interlocks w/ cuticle of hair shaft
Henle’s layer (outermost)
Huxley’s layer
What are the layers of the hair shaft?
Medulla (innermost)
Cortex
Cuticle (outermost)
What is a unique feature of keratinocyte stem cells?
Can reestablish epidermis in severely burned patients
Have a migration and signaling pathway
What are the migration pathway of keratinocyte stem cells? (3)
Bulb-epidermis stem cell pathway
Bulb-hair stem cell pathway
Bulb-sebaceous gland stem cell pathway
What are the signaling pathways of keratinocyte stem cells? (2)
Wnt signaling pathway
Notch signaling pathway
What are Meissner’s Corpuscle? What is their function?
(Tactile corpuscle)
Type of mechanoreceptor
Type of nerve ending in the skin responsible for sensitivity to light touch
What are Pacini Corpuscles
One of the 4 major types of mechanoreceptors
Nerve endings in skin responsible for sensitivity to vibration and pressure
What 3 layers are the walls of blood vessels (except capillaries) characterized by?
Tunica intima
Tunica media
Tunica adventitia
What are the components of the respiratory mucosa? (3)
Respiratory epithelium = pseudostratified cilitated columnar epithelium (lines most conducting structures)
Lamina propria/basement membrane - thin layers of CT
Submucosa - dense irregular CT
What are the components of the respiratory system? (6)
Nose and Olfactory mucosa
Paranasal sinuses
Pharynx (opening of pharynx into esophagus)
Larynx
Trachea
Lung
What type of epithelium lines the nares?
Stratified squamous epithelium continuous w/ epidermis with sebaceous glands and hair follicles
Mucosa at nasal septum:
pseudostratified ciliated columnar = respiratory epithelium
Basement membrane
Lamina propria
What type of epithelium is respiratory epithelium?
Pseudostratified ciliated columnar epithelium
Where is olfactory epithelium located? What is the epithlium type and what feature do they not possess?
Nasal cavity of roof
Pseudostratified columnar epithelium w/out goblet cells
No distinct basement membrane
What are the cell types of olfactory epithelium? (4)
Basal cells w/ pigment granules
Olfactory cells
Olfactory glands of Bowman
Sustentacular cells (pigment cells) w/ pigment granules
What are basal cells (with pigment granules) of the olfactory epithelium?
Stem cells that give rise to immature olfactory cells
What are olfactory cells? Describe the characteristics of apical and basal ends
Bipolar neurons
Cilia contain GPCR odor-specific receptors
Apical end = projects into nasal cavity as knoblike ending w/ nonmotile cilia
Basal end = extends as an unmyelinated axon, bundled w/ other similar axons, thru ethmoid plate to mitral cells in olfactory bulb
Get replaced by basal cells when old (senesce)
What are the functions of Olfactory glands of Bowman? Where are they located?
Lamina propria (CT layer)
Secrete odorant-binding protein which binds to odorant molecule in nasal cavity
What are the steps that occur in generating an action potential in olfactory cells?
Odorant-binding protein + odorant molecule
binds odorant receptor protein (G protein) on olfactory cell cilium
Activates Adenyl Cyclase
ATP –> cAMP –> Na+ channels open –> AP
What are the 3 structures of the nasopharynx? Explain their characteristics
Mucosa - respiratory epithelium, lamina propria w/ FECT, mucous glands, serous & mixed glands, diffuse lymphatic tissue
Submucosa - loose CT, MALT
Waldeyer’s ring - ring of lymphoid tissue around nasopharynx, tonsils and adenoids
What are the characteristics of mucosa of the nasopharynx?
Respiratory epithelium - pseudostratified ciliated w/ goblet cells
Lamina propria with FECT, mucous glands, serous and mixed glands, and diffuse lymphatic tissue
What are characteristics of the submucosa of the nasopharynx?
Loose CT
MALT
What are Waldeyer’s ring? Where are they located in the nasopharynx?
Ring of lymphoid tissue around the nasopharynx
Tonsils and adenoids
What are the two major components of the larynx?
Epiglottis
Vestibular folds (false vocal cords)
True vocal cords
What are the 3 general structures of the epiglottis? What type of epithelium do they contain? What’s the lamina propria made up of? LPC
Lingual surface (faces back of tongue)
Stratified squamous epithelium
Lamina propria w/ loose CT & elastic fibers
Pharyngeal surface (faces pharynx)
Pseudostratified ciliated epithelium
Lamina propria = tubuloacina seromucous glands
Core of epiglottis consists of elastic cartilage
What type of epithelium is contained with the vestibular folds? Lamina propria?
False vocal cords
Pseudostratified ciliated epithelium
Lamina = seromucous glands
What is the general histology of intrapulmonary bronchi?
(beyond primary bronchi)
Mucosa - similar to trachea & extrapulmonary bronchi, elastic fibers and mucosal folds (smooth muscle)
Submucosa - loose CT, lymphatic tissue, mixed and mucous glands
Adventitia - hyaline cartilage plates w/ dense FECT
What type of epithelium is within the true vocal cords of the larynx?
Stratified squamous epithelium (resists abrasion)
lack seromucous glands in lamina propria
Remainder of larynx covered w/ pseudostratified ciliated epithelium
What types of cartilage and muscle are within the larynx?
Elastic and Hyaline cartilage
Skeletal muscle
What 2 locations in the larynx contain stratified squamous epithelium?
Lingual surface of the epiglottis
True vocal cords
The rest contain pseudostratified ciliated columnar
What are the 3 components of the trachea?
Mucosa
Submucosa
Adventitia
What are the characteristics of the mucosa and submucosa of the trachea?
Mucosa - respiratory epithelium w/ thick basement membrane
Lamina propria = delicate FECT & lymphatic tissue
Submucosa - sero-mucous glands
Describe the adventitia of the trachea
Cartilages that surround the trachea
16-20 horseshoe-shaped cartilages interconnected via FECT
Faced posteriorly, contain FECT, mucous membrane and smooth muscle/trachealis muscles
Mixed glands and capillaries
Become circular once in bronchi
What are the extrapulmonary components of the lungs?
Left and Right Primary Bronchi
From trachea –> primary bronchi; replacement of hyaline cartilage rings by irregularly shaped cartilaginous plates
List the general structure of the lungs from trachea to alveoli
Trachea
Primary Bronchi
Secondary Bronchi/Segmental
Tertiary Bronchi
Bronchioles
Terminal Bronchioles
Respiratory Bronchioles
Alveolar Sac
Which lung structure begins the intrapulmonary segments?
Segmental/Secondary Bronchi
Contain circular rings w/ hyaline cartilage that transition to irregular plates
What are characteristics of the bronchioles?
No Cartilage
No glands
Few goblet cells
Large amount of smooth muscle
Epithelium = ciliated columnar w/ few goblet cells –> ciliated cuboidal w/ no goblet cells (terminal bronchioles)
Terminal bronchioles –> Respiratory bronchioles
Where in the lung does gas exchange start at?
Respiratory bronchioles
After the terminating bronchioles
What are the characteristics of respiratory bronchioles?
Low columnar –> low cuboidal
Cilia in larger respiratory bronchioles
No goblet cells
Walls contain smooth muscle within FECT
Few alveolar outpocketings
Characteristics of Alveolar ducts?
Continuations of respiratory bronchioles
Cone-shaped
Squamous epithelium
Wall = smooth muscle w/ FECT
Alveolar sac = several alveoli
Define Type I alveolar cells/Type I Pneumocytes
Less numerous than Type II
Cover largest suface area (more thinner)
Define Type II Alveolar Cells/Pneumocytes
Produce surfactant
Cuboidal/rounded
Stem cells for Type I and Type II
Define Pores of Kohn
Openings between adjacent alveoli
Allows for alternate pathways for air from one alveoli to the next
What are the cell types of the mucosa of the respiratory system?
Ciliated columnar
Nonciliated columnar
Stem Cells
Goblet Cells - mucous secreting; stem cells
Neuroendocrine cells/Small granule cells
What are the general characteristics of ciliated/nonciliated columnar cells and stem cells?
Nonciliated - contain microvilli, no cilia
Stem cells - basal cells of pseudostratified epithelium, self-replace
What is the function of neuroendocrine cells of the respiratory system?
Release catecholamines
More prevalent in infants; sensory reception(?)
What two cells secrete surfactant?
Clara and Type II Alveolar/Pneumocytes
Characteristics of Type II Alveolar cells
Lamellar bodies = Distinctive under EM; contain lecithin
Phagocytize old surfactant; more round
Can divide and replace Type I
Secreted from apical domain of cells
Combine w/ proteins from Clara cells
Produce phospholipid-protein surfactant that coats alveolar walls
Characteristics of Type I Alveolar/Pneumocytes
Thin cytoplasm
covers 95% of alveolar surface
Basal lamina may be fused with basal lamina of nearby capillaries
Define Clara cells, where are they found
Secrete surfactant & lipoprotein that prevents collapse of terminal bronchioles during exhalation
Bronchioles
Identified by apical surface that bulges into lumen of airway
Abundant SER; greater # with less ciliated columnar cells
What are dust cells and what are their roles?
Macrophages; derived from monocytes
Phagocytize pollutants, bacteria, surfactant
What relation does dust cells have with congestive heart failure?
Generate heart failure cells (iron-containing dust cells) due to dust cells phagocytizing fluid that contains breakdown products of Hb that leaks into alveolar spaces
What are the 3 components of the air-blood respiratory barrier? What is its characteristic?
Thin capillary endothelium
Thin epithelium of pneumocyte
Intervening basal lamina produced by Type I and Type II
Permits gas exchange but doesn’t allow fluids or cells to enter alveoli
What is the most important opsonin?
C3b
