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UKCD Histo Skin
answers to skin test objectives
| Question | Answer |
|---|---|
| What two general layers compose the integumentary system? | Epidermis and dermis. |
| How is the deeper layer of these two layers of the Integumentary system subdivided? | Papillary dermis (that in the dermal papillae) and the reticular dermis. The latter blends with the underlying hypodermis (superficial fascia) that blends with the epimysium of underlying musculature (deep fascia). |
| What is a dermal papillae? | A finger-like projection of dermis that sticks up into the overlying epithelium (epidermis). |
| What is a rete peg? | The corresponding projection of epithelium that sticks down into the dermis between dermal papillae. |
| What comprises the dermal-epidermal junction? | This peg-and-socket like interface uses 3 structures to adhere the epithelium to the underlying dermis: hemidesomsomes; basal lamina; and anchoring fibrils. |
| What is a Langer’s line and what causes them? | Tension lines exhibited by the skin as a result of the tension of the underlying elastic fibers of the dermis. |
| What 5 layers compose the epithelium? | From the bottom up: stratum germinativum (basale); stratum spinosum; stratum granulosum; stratum lucidum and stratum corneum. |
| What are the characteristics of S. germinativum? | proliferating cells |
| What are the characteristics of s. spinosum? | cells with processes that have desmosomes connecting them to adjacent processes |
| What are the characteristics of s. granulosum? | flattened cells with dark granules of keratohyalin |
| What are the characteristics of s. lucidum? | tightly packed dead cells filled with keratin filaments |
| What are the characteristics of s. corneum? | squames of soft keratin, noinucleus or organelles. |
| Which layer(s) are added/missing between thick and thin skin? | S. lucidum rarely seen (absent) in thin skin. S. corneum much reduced in thickness in thin skin. |
| Name the three specialized cells of the stratum germinativum/spinosum. | Melanocytes; Langerhans cells; and Merkel cells. |
| What is the function of each of Melanocytes? | protect underlying proliferating cells from UV rays |
| What is the function of each of Langerhans cells? | antigen presenting cells for contact dermatitis |
| What is the function of each of Merkel cells? | unencapsulated mechanoreceptors. |
| List the appendages of the skin. | Hair follicles, nails, sebaceous glands, arrector pili m., eccrine sweat glands, apocrine sweat glands. |
| Where is hard keratin found in the hair follicle? | Primarily in the cortex of the shaft of the hair. |
| Where is soft keratin found in the hair follicle? | In the internal root sheath as well as the medulla of the hair. |
| What comprises the external root sheath? | A tubular invagination of the overlying epithelium. |
| What comprises the internal root sheath? | A sleeve-like lining of soft keratin between the external root sheath and the hair shaft that extends from the base of the hair follicle up to the level of where the sebaceous glands empty into the follicle. |
| Name a gland associated with the hair follicle. | The sebaceous gland. |
| What does this gland secrete? | Sebum, an oil-based complex. |
| What type of secretory mode does the hair follicle gland exhibit? | Holocrine. The whole cell dies and becomes a cell membrane-defined bag of sebum. |
| What is its function of sebum secretion? | It is a protective layer that extends out over the hair shaft keeping it soft, supple and waterproof. |
| What role does the arrector pili muscle play in this secretory release? How? | The gland is located between the muscle and the follicle. When the muscle contracts the gland is squeezed and the sebum expressed. |
| What type of muscle is the arrector pili? | Smooth muscle (involuntary). |
| Which division of the nervous system innervates the arrector pili? | Autonomic. Sympathetic fibers cause it contract. No parasympathetic innervation for relaxation, simply a lack of sympathetic stimulation will relax the muscle. |
| Name the two parts of a sweat gland. | The secretory acinus and the duct. |
| What type of epithelium composes each part of the sweat gland? | The secretory acinus is composed of tall columnar-like secretory cells that are wider at their base than at their apex (pyramidal). The sweat gland duct is composed of stratified cuboidal epithelium. |
| Where is each part of the gland located in the integument? | The secretory portion is located deep in the dermis or superficial hypodermis. The duct traverses the distance between here and the base of the epithelium. |
| What type of secretion occurs in the sweat gland? | Eccrine sweat glands exhibit a merocrine mode of secretion. Merocrine refers to granules being excreted individually from the apical aspect of the cell. |
| How do eccrine sweat glands differ from apocrine glands? | They don’t - only in location as these apocrine glands are located in the axilla/genital regions. Both secrete in a merocrine fashion. |
| Give an example of an eccrine and apocrine gland. | Eccrine - sweat gland on surface of palm. Apocrine - sweat gland of axilla. |
| Name the two vascular plexuses that are associated with the skin | Subcutaneous plexus and Subpapillary plexus |
| What is the function of the Subcutaneous plexus? | at dermal-hyodermal (subcutaneous) jcn. Small arteries extend from here to the base of hair follicles and sweat glands. |
| What is the function of the Subpapillary plexus? | located along the jcn. of the papillary and reticular layers of the dermis. They are responsible for supplying the overlying epithelium with oxygen/nutrients by diffusion and give the skin its pink coloration. |
| What is an A-V shunt? | A by-pass where blood can pass between arteriole and venule without going through the capillary bed. |
| What is the function of AV shunts? | Allow by-pass of the subpapillary plexus to conserve body heat. |
| What gives the skin its pink color? | The blood flowing through the capillary beds in the dermal papillae as well as in the dense subpapillary plexus. |
| What effectively causes the A-V shunts to come into action? | Precapillary sphincter (innervated by the ANS) constrict and close off access to the superficial capillary beds, shunting blood through the A-V shunt. Effective in thermoregulation. |
| What composes the nail? | A thick plate of hard keratin (nail or nail plate) that grows out from the nail groove. |
| What is the eponychium? | The cuticle (or layer of skin located over the top of the nail groove). |
| What is the hyponychium? | The pad of skin under the free edge of the nail plate. |
| What is the underside of the nail attached to? | The nail bed (dermis). |
| List the three most common sensory nerve endings associated with the skin. | Free nerve endings; Meissner’s corpuscle; Pacinian corpuscle. |
| Which of these 3 free nerve endings, Meissner’s corpuscle, and Pacinian corpuscle types is most superficial? | The free nerve endings. |
| Into which layer does the most superficial of free nerve endings, Meissner’s corpuscle, and Pacinian corpuscle extend? | Free nerve endings enter the epithelial layer. |
| Which of the free nerve endings, Meissner’s corpuscle, and Pacinian corpuscle receptors are considered encapsulated? | Meissner’s and Pacinian corpuscles. |
| Name an unencapsulated receptor found in the epithelium. | The Merkel cell - a mechano (pressure) receptor. |
| What is the functional classification of Free nerve endings? | are thermoreceptors and nociceptors |
| What is the functional classification of Meissner’s corpuscles and Pacinian corpuscles? | are pressure sensitive mechanoreceptors. |
| What is the specific function of Free nerve endings? | detect pain and temperature |
| What is the specific function of Meissner’s corpuscles? | detect/sense fine touch |
| What is the specific function of Pacinian corpuscles? | sense/detect deep touch/pressure. |
Created by:
wiechartm
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