Skin and subcutaneous tissue
All are true regarding epidermis except
A. Keratinocytes replaced via mitoses in the cells of the stratum granulosum
B. Stratum lucidum is almost absent in eyelid skin
C. Melanocytes are dendritic cells of neural crest origin, usually located in the basal epidermis.
D. Ethnic differences in skin color are determined by the number of melanocytes.
Not true regarding receptors in human skin
A. Meissner corpuscles, respond to superficial light touch
B. Pacinian corpuscles transmit slow events but damp out fast changes
C. Merkel endings and Ruffini endings react to touch pressure
D. Pacinian corpuscles respond to vibration with a fast response and quick recovery
Which is not true regarding glands of skin
A. Eccrine sweat glands are most numerous on the soles of the feet
B. Mammary glands of the breast are modified apocrine sweat glands
C. Apocrine sweat glands release viscous, protein-rich product into a duct open to the skin under hormonal stimulation
D. Sweat glands play a regenerative role in skin damage of second-degree cutaneous burns
Innervation of skin does not include
A. Adrenergic stimulation of muscarinic receptors that induces sweating
B. Apocrine sweat glands receive adrenergic sympathetic innervation
C. Emotional sweating due to stress, fear, pain, and sexual stimulation is mediated through norepinephrine
D. Cornea contains free nerve endings served by only unmyelinated axons
Not true regarding sebaceous glands of skin are
A. They are most scarce on the scalp
B. Activity of the sebaceous glands is mainly controlled by androgens
C. The meibomian glands are the large sebaceous glands in the eyelid
D. Sebaceous glands are also found on the hairless surfaces of the lips
Thus, skin has the potential for a blood supply 20–100 times greater than its metabolic and thermoregulatory requirements.
- The epidermis is thickest on the palms, soles, back and buttocks and thinnest on eyelids (0.5–1 mm on the sole of the foot, 0.05–0.09 mm on the eyelid). The skin of the eyebrows is thick, coarse, and hairy.
- The venous drainage of the skin is via both valved and non valved veins.
- The hair follicles and skin glands are derived from the epidermis but are deeply embedded in the dermis.
- The palms of the hands and the soles of the feet are etched by distinct alternating ridges and grooves that together constitute dermatoglyphics tha is best-known physical characteristic for personal identification.