Integumentary System Development
A 19 year old female presents to the emergency room with a serious staph infection covering her abdomen. She explains that she just returned from spring break where became so intoxicated by the pool one day that she puked on herself before passing out in her bikini in the sun. The infection was able to infect her skin via the following means:
- The combination of stomach acid and UVB radiation penetrated the dermis, allowing for infection of the staph bacteria.
- The combination of stomach acid and UVA radiation penetrated the thick skin of the abdomen, allowing for infection of the staph bacteria.
- The spring break party was in Australia where there is a hole in the ozone and the girl was burnt severely from UVC radiation, allowing for infection of the staph bacteria.
- The combination of stomach acid and UVB radiation penetrated the thin skin of the abdomen, allowing for infection of the staph bacteria.
- The combination of UVA and UVB radiation penetrated the thin skin of the abdomen allowing for infection of the staph bacteria.(Answer A: Lecture #51. Laying in the sun all day would cause severe burning due to the UVB rays. This in combination with the acid from the stomach would cause deeper penetration. Staph bacteria would have to reach the dermis, as this is where the vasculature is to help spread the infection.)
A skin disorder that results in excessive keratinization charachterized by dryness and fishskin-like scaling:
- Nevus flammeus
- Albanism(Answer B)
Identify the structure in the image to the right:
- Arrector pili
- Meissner’s corpuscle
- Eccrine gland
- Sebaceous gland
- Mammary gland(Answer C)
All of the following are major features/properties of the skin EXCEPT:
- Production of chemical substances that protect against bacterial growth
- Production of melanin as a defence against UV radiation
- Use of keratin and glycolipids to allow for better absorption of salts
- Secretions that act against bacteria
- DNA electron absorption and conversion of UV radiation to heat(Answer C)
Though not always considered an official layer of the skin, the hypodermis is an important structure in our bodies because:
- It provides the primary vasculature to the integument, helping in thermoregulation.
- It stores excess fat so as to avoid excess organ fat causing diseases like fatty liver.
- It is envagenated with ligamentous structures that help hold our organs in place
- It provides a source of energy reserve
- It hosts a number of microscopic structures that aid in course touch sensation(Answer D)
The deepest layer of the epidermis, stratum basale, consists of which of the following specialized cells?
- Melanocytes and hair follicles
- Merkel cells and Dendritic cells
- Merkel cells and fibroblasts
- Langerhans cells and subcutaneous adipose tissue
- Adipose tissue and sebaceous glands
- (Answer B: The epidermis consists of keratinocytes, melanocytes, dendritic (Langerhans) cells, and Merkel(tactile) cells. The dermis consists of fibroblasts, macrophages, sebaceous glands, and sweat glands. The hypodermis is mostly subcutaneous adipose tissue. Lecture #52 Integumentary Physiology.)
Thermoregulation in the skin behaves differently in order to maintain homeostatic needs to the body. With increased temperatures the body will react in which response?
- Increase in body temperature will send signals to the thermoreceptors in the hypothalamus and skin to vasodilate.
- Increase in body temperature will send signals to the thermoreceptors in the thalamus and skin to vasodilate.
- Increase in body temperature will send signals to the thermoreceptors in the hypothalamus and skin to vasoconstrict.
- Increase of body temperature will send signals to the thermoreceptors in the thalamus and skin to vasoconstrict.
- Decrease of body temperatures will send signals to the thermoreceptors in the thalamus and skin to vasoconstrict. (Answer A)
Which statement is true concerning eccrine and apocrine sweat glands?
- Apocrine sweat glands are smaller than eccrine sweat glands and ducts empty to the surface of the skin.
- Eccrine sweat glands are abundant on palms and soles and are regulated by the parasympathetic nervous system.
- Apocrine sweat glands secrete an odorous substance and eccrine sweat glands empty into hair follicles.
- Eccrine sweat glands secrete a substance that is mostly composed of water and apocrine sweat glands secrete a more viscous substance. (Answer D)
Biochemical Composition of Skin
α-keratin is found in intermediate filaments and expressed in hair, skin, and nails. Which amino acids would most likely enrich Type I α-keratin at a physiological pH to intertwine with Type II α-keratin for the formation of a keratin dimer?
- H,K,R(Answer D: Type I alpha keratin are acidic amino acids. Though answer choice D contains a nonpolar amino acid, it would most likely pair with Type II alpha keratin since it contains negative amino acids at a pH of 7.)
Keratin is composed of electrostatic bonds between dimers. The hydrogen bonds and disulfide covalent bonds allow for tetramers to stabilize. The composition of keratin allows for cross linkage to occur in the epidermis through the process of transglutaminase. Which two amino acids must be present for the process to occur in keratinocytes?
- Arginine as the acceptor protein and Glutamine as the donor protein
- Lysine as the donor protein and Arginine as the acceptor protein
- Glutamine as the acceptor protein and Lysine as the donor protein
- Glutamine as the donor protein and Lysine as the acceptor protein
- Arginine as the donor protein and GLutamine as the acceptor protein(Answer C: Lysine must be the donor protein and Glutamine must be the acceptor protein for transglutaminase to occur.)
UV radiation penetrates the skin damaging the DNA within a keratinocyte. Due to the damage, the body starts a natural reaction for future protection from UV damage. Which answer choice most likely resembles the pathway keratinocytes conduct for further protection?
- The keratinocyte produces POMC via p53 to activate ACTH for anti inflammatory response, thus repairing the damage
- The keratinocyte dies due to p53 activating p21, preventing CDK 1 activation
- The keratinocyte activates p53 which stimulates POMC production generating α-MSH causing pigment production through cAMP cascade
- The keratinocyte signals p53 to produce pigment within the cell via MITF and carry it to the melanocyte via melanosomes
- The keratinocyte is protected from further damage due to p53 causing a POMC production, making 𝝱-endorphins for pigment production (Answer C: DNA damage will trigger a p53 response to make POMC. POMC is one large polypeptide post-translationally modified into several peptides: ACTH-cortisol production, 𝝱-endorphins for pain reduction, and α-MSH for MITF production via cAMP cascade which will produce pigments. The pigments are taken to keratinocytes via the melanosomes. Lecture #53 Biochemical Composition of Skin)