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43 Cards in this Set
- Front
- Back
Describe the physiology of epithelial cells. |
- tightly joined together by adhesion molecules & tight junction proteins - replaced by underlaying stem cells - POLARIZED MORPHOLOGY (apical side exposed to commensal microbes/environment and basolateral side protected from exposure) |
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Where are PRRs found on epithelial cells? |
concentrated on basolateral side - commensal microbes tolerated on apical side - PRRs alert underlaying immune system of microbial invaders/tissue damage |
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What are the functions of the skin? |
1. nutrient synthesis 2. thermoregulation 3. osmoregulation 4. protective barrier against stressors |
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What are the differences between the skin of cartilaginous fish vs. bony fish? |
- cartilaginous fish have PLACOID SCALES that rise out of epidermis to protect skin
- bony fish covered with MULTILAYERED EPIDERMIS that is coated in mucus (contains antimicrobial proteins/peptides) |
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What is the function of Goblet cells? |
- produce mucus |
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What is the function of mucus? |
- protect viable epidermis from surrounding environment |
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What are the functions of melanophores? |
1. provide skin pigmentation 2. help to sequester reactive oxygen species that are generated during oxidative stress |
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Where are neural sensory cells located on a fish? |
- along the lateral line |
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What is the stratum corneum function? |
- non-viable layer of cells covered by epidermis - constantly replaced by epithelial cells called keratinocytes (differentiate from underlaying pluripotent stem cells) - only found in birds and mammals |
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What is the function of the stratum corneum? |
- protects underlaying viable epidermis from abrasion, water loss, UV radiation, toxic chemicals & microbial invasion |
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What are two differences found in the skin of birds? |
- avian skin lacks sweat glands - uropygial gland replaces the sebaceous glands of mammals (produces lipids to condition feathers and repel water) |
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How are hair and feathers produced? |
from keratin produced by keratinocytes |
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What are the functions of hair/feathers? |
1. thermoregulation 2. protective barrier |
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Besides producing hair/feathers, keratinocytes also play an important role in the immune response. Describe. |
keratinocytes protect against invasion and maintain tolerance to commensal microflora by communicating with the SALT |
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What does hair thickness influence? |
- skin conditioning - attachment of parasites (potential disease vectors) - potential damage caused by skin abrasion |
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What 4 mammalian epidermis factors are highly variable across species?
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1. hair thickness 2. stratum corneum thickness 3. amount of melanocyte pigmentation 4. sebaceous gland secretions |
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What does dark skin pigmentation allow for? (thicker stratum corneum, higher lipid content, and replaced more rapidly) |
1. retain water effectively 2. more resistant to chemical and microbial exposure 3. nutritionally adaptive feature |
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What diseases are LIGHT skin humans susceptible to? |
- spina bifida - caused by UV-induced folic acid depletion during pregnancy |
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What diseases are DARK skin humans susceptible to? |
- Rickets disease - immunodeficiency - caused by insufficient vitamin D production during pregnancy and early life |
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What is specific to cattle epidermis? |
- very thick stratum corneum |
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What is specific to sheep epidermis? |
- secrete unique moisture barrier made of lanolin (long chain waxy esters rather than oils) from sebaceous glands |
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How are sweat glands distributed on primates? |
distributed all over the body (allows for efficient thermoregulation) |
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What determines the number of FUNCTIONAL sweat glands on the mammalian body? |
environmental temperatures experienced during early life epigenetically affect # of sweat glands that are functional |
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What two compounds does sweat contain? What are their functions? |
1. dermicidin 2. lactoferrin - antimicrobial peptides that help control microbial invaders and commensal microbes |
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Where are the sweat glands of hooved animals found? |
under the axilla (armpits) |
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Where are the sweat glands of pigs, dogs & cats found? |
concentrated on footpads and snout |
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What is a hapten? |
small molecular weight reactive chemicals <1000 Da - can be found in cosmetics, jewellery, cleaning agents |
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What is allergic contact dermatitis? |
repeated exposure to happens causes a cell-mediated hypersensitivity reaction that develops into a disease called allergic contact dermatitis |
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What is mucus? What is it made of? |
- a gel gradient - composed of: a) mucin proteins b) lipids |
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What are the functions of mucus? (7) |
1. physical barrier preventing attachment 2. lubricates to reduce abrasion 3. traps and removes microbes, antigens, chemicals (facilitated by TURBULENT AIRFLOW in trachea and bronchi) 4. maintains hydration 5. outer loose layer acts as adhesive surface 6. inner dense layer provides a matrix to concentrate antimicrobial proteins 7. facilitates removal of motile immune cells that have engulfed foreign particles
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What is the function of epithelial cells in nasal and oral cavities, trachea and bronchi? |
- protect against pathogen invasion - facilitate tolerance to commensal microflora - communicate with NALT & BALT |
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What are the functions of Goblet cells in nasal and oral cavities? (2) |
- produce mucus - produce surfactant proteins |
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What is the function of Clara cells? |
secrete antimicrobial proteins and peptides |
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What is the function of M-cells? |
sample antigens from mucus and pass them along underlaying tissue macrophages and DC for antigen-presentation |
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What are pneumocytes? |
epithelial cells that make up the alveolar sacs |
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What is the function of Type 2 pneumocytes? |
Type 2 - replace Type 1 - produce surfactant proteins that reduce surface tension preventing lung collapse - antimicrobial and immunomodulatory properties |
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How is mucus removed? |
beating of ciliated epithelial cells & coughing |
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What is the Hygiene Hypothesis? |
lack of exposure to certain microbes during early life development can affect immune development and increase risk of atopic diseases |
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What are atopic diseases? Examples? |
- caused by antibody-mediated hypersensitivity reactions - ex. asthma, food allergy, atopic dermatitis |
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What makes up the small intestine epithelium? |
finger-like villi and gland-like crypts |
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What is the function of SI crypts? |
contain pluripotent stem cells that proliferate and differentiate into other epithelial cell types (ex. absorptive enterocytes, Goblet cells, enteroendocrine cells, M-cells, Panth cells) |
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What is the function of Panth cells in the SI? |
secrete antimicrobial peptides |
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What are the major differences between the small and large intestine epithelium? |
large intestine is i) NOT lined with villi ii) Panth cells are NOT found iii) cells communicate with GALT |