practice questions
Which glands secrete an oily product that softens the skin and hair?
Sebaceous glands
The reason that the nail bed appears pink is the presence of a large number of melanocytes in the underlying dermis.
false- it is because of capillaries
What feature of the prickle cells in stratum spinosum causes them to have pointy projections after tissue preparation?
Desmosomes Cells typically shrink during tissue preparation, and since these cells are attached by desmosomes, the membranes are pulled slightly outward at the points of cellular attachment.
T/F Vitamin D precursors are produced in the skin in the presence of sunlight. These chemicals are important for the transport of sodium in our intestines.
False It is true that vitamin D precursors are produced in the skin as modified cholesterol is converted into cholecalciferol when the skin is exposed to UV light. However, vitamin D plays various roles in calcium, not sodium, metabolism. For example, calcium cannot be absorbed from the digestive tract without vitamin D.
You are asked to classify an exocrine gland found in the skin based solely on the chemical analysis of its product, which turns out to be a hypotonic fluid consisting of about 99% water with a pH of 5. It contains NaCl, traces of urea and ammonia, and a peptide called dermcidin, but lacks fats and proteins. How would you classify this gland?
Eccrine gland secretion, commonly called sweat, is a hypotonic filtrate of the blood that passes through the secretory cells of the sweat glands and is released by exocytosis. It is 99% water, with some salts (mostly sodium chloride), traces of metabolic wastes (urea, uric acid, and ammonia), and a microbe-killing peptide called dermcidin. Normally, sweat is acidic with a pH between 4 and 6.
Thick skin has a more extensive dermal layer than thin skin.
False
New portions of a nail are produced at the cuticle.
False The nail matrix is the thickened proximal portion of the nail bed responsible for nail growth. The cuticle is the part of the proximal skin fold, or nail fold, that projects onto the nail body.
What is the most common cell type in the epidermis?
Keratinocytes are the primary cells that form the stratified layers of the epidermis.
Which skin-color-associated, pigment-producing cell is located in the labeled layer D?
Melanocyte Melanocytes within the stratum basale produce the pigment melanin, which is deposited within the deeper layers of the epidermis.
Which of the following statements indicates the way in which the body's natural defenses protect the skin from the effects of UV damage?
Prolonged exposure to the sun induces melanin dispersion, which in turn acts as a natural sunscreen.
Which of the following is NOT a function of sebum?
Protection from UV This is false; it is melanin (not sebum) that protects the skin from the damaging effects of UV radiation. Sebum serves as a lubricant, an antibacterial agent, and protects against water loss.
Pigment can be found in several layers of the epidermis. In which layer would you expect to find the cells that produce melanin?
Stratum basale 10−25% of the cells in the stratum basale are melanin producing cells called melanocytes. Their branching processes extend among the surrounding cells, reaching well into the more superficial stratum spinosum layer.
T/F The glycolipids secreted by keratinocytes in the stratum granulosum help reduce water loss across the epidermis.
T Keratinocytes in the stratum granulosum accumulate two types of granules, keratohyaline granules and lamellar granules. The lamellar granules contain a water-resistant glycolipid that is secreted into the extracellular space. Together with tight junctions, the glycolipid plays a major part in slowing water loss across the epidermis.
What is the role of the hair matrix? The hair matrix allows hair to "stand on end," or become erect. The hair matrix serves as a sensory receptor. The hair matrix produces hair. The hair matrix serves as an anchor for the hair shaft.
The hair matrix produces hair.
Which stratum of the epidermis contains the stem cells responsible for regenerating the more superficial layers?
The stratum basale is the deepest layer of the epidermis and consists of one layer of actively mitotic stem cells. The stem cells in this layer generate the cells that will migrate to the more superficial layers: spinosum, granulosum, and corneum.
Respiratory failure can lead to a change in the color of the skin, which is more evident in light-skinned individuals. Which pigmentation factor is affecting this change?
When hemoglobin is poorly oxygenated, the skin may take on a bluish-gray tint, especially in the mucous membranes and nail beds. Cyanosis, or blueness, can be a sign of respiratory or cardiovascular problems.
The function of the root hair plexus is to ________.
allow the hair to assist in touch sensation (nervous endings)
The major regions of a hair shaft include all of the following EXCEPT ________. medulla cortex cuticle external root sheath
external root sheath
The dermis is a strong, flexible connective tissue layer. Which of the following cell types are likely to be found in the dermis?
fibroblasts, macrophages, and mast cells
A dendritic or Langerhans cell is a specialized ________.
phagocytic cell
Cells of the stratum spinosum have many interlocking desmosomes that will remain between the cells as they migrate to the stratum corneum. These cell junctions serve the body by ________.
preventing mechanical stress or trauma from damaging the epidermis
The epidermis consists of five layers of cells, each layer with a distinct role to play in the health, well-being, and functioning of the skin. Which of the following layers is responsible for cell division and replacement?
stratum basale
Which layer of the epidermis will be supplied with the highest levels of oxygen from the blood?
stratum basale
The reason the hypodermis acts as a shock absorber is that ________.
the major part of its makeup is adipose, which serves as an effective shock absorber
what is NOT a function of the hypodermis? to supply cells to replace those lost from the epidermis to loosely connect the skin to underlying tissue to insulate the body from heat loss to store energy
to supply cells to replace those lost from the epidermis Cells to replace those lost in the epidermis are provided by the basal cells of the epidermis itself.
