MLT GlobeAnatomy: Skin, lymphatics & immune organs
24 Anatomy MCQs on Skin, lymphatics & immune organs with answers and explanations.
A skin biopsy shows the most superficial layer. Which description of the epidermis is correct?
The epidermis is avascular keratinised stratified squamous epithelium lying above the dermis; it receives nutrients by diffusion and renews in roughly 4 weeks.
Which vessels carry lymph rather than blood?
Lymphatic vessels return tissue fluid to the venous system. Arteries, veins and capillaries are blood vessels.
Hair, nails and glands are accessories of the integumentary system. Which is its main organ?
The skin is the principal organ of the integumentary system; hair, nails, sweat and sebaceous glands are its appendages. Bone belongs to the skeletal system.
In a skin biopsy, the dermis is seen to consist mainly of which tissue?
The dermis is chiefly dense irregular connective tissue with collagen bundles running in many directions, giving strength in all planes.
A pathologist sees aggregated lymphoid follicles in the ileal mucosa. What are these structures?
Peyer patches are lymphoid follicles in the small-intestinal wall, especially the ileum, that sample gut antigens. They are not part of the spleen or tonsils.
Which protein gives the outer epidermal cells their tough, water-resistant quality?
Keratinocytes fill with keratin as they move toward the surface, forming a protective barrier. Melanin is a pigment and myelin insulates nerve fibres.
When does the thymus normally begin to involute (shrink)?
The thymus is largest relative to body size in childhood and starts to atrophy after puberty, being gradually replaced by fat.
By surface area and weight, which is the largest organ of the human body?
The skin covers about 1.5–2 m² and weighs several kilograms, more than the liver, which is the largest internal organ.
Plasma cells packed with rough endoplasmic reticulum are specialised for which activity?
Ribosomes on rough ER synthesise secretory and membrane proteins such as antibodies. Smooth ER handles steroid synthesis and detoxification; mitochondria make ATP.
Sweat glands are most densely concentrated in which skin region?
Eccrine sweat glands are densest on the palms and soles, which is why emotional sweating is noticed there first.
Where in the body is thick skin found?
Thick skin with a stratum lucidum and prominent ridges covers palms and soles. It lacks hair follicles and sebaceous glands.
The oily secretion that lubricates hair and skin comes from glands that usually open into hair follicles. These are the:
Sebaceous glands secrete sebum into hair follicles by holocrine secretion. Eccrine glands produce watery sweat, and ceruminous glands produce ear wax.
Hair colour comes from pigment made by which cells in the hair bulb?
Melanocytes make melanin and pass it to keratinocytes of the hair shaft. Merkel cells are touch receptors.
Which vessel runs up alongside the vertebral column, drains most of the body's lymph and empties into the left venous angle?
The thoracic duct begins at the cisterna chyli and joins the junction of the left subclavian and internal jugular veins. The right lymphatic duct drains only the upper right body.
Which of these lies in the epidermis rather than the dermis?
The dermis contains vessels, nerve endings, sebaceous and sweat glands. The epidermis is avascular, and its outermost keratinised layer is the stratum corneum.
Roughly what total skin surface area does an average adult have?
An adult's skin covers about 1.5–2 m², making it the largest organ by area; body surface area estimates of this size are used in dosing calculations.
The fatty superficial fascia (panniculus adiposus) under the skin is notable because it:
Superficial fascia is loose fatty tissue through which cutaneous nerves, vessels and lymphatics run to reach the skin.
Sebaceous glands are ABSENT from which skin region?
Sebaceous glands occur wherever there is hair and in some hairless sites (lips, areola) but are absent from the thick glabrous skin of the palms and soles.
A surgeon aligns an incision with skin cleavage lines, following collagen fibre direction, to reduce scarring. These lines are:
Langer's (cleavage) lines follow dermal collagen orientation; incisions parallel to them gape less and heal with thinner scars.
Which of these is NOT counted as an appendage (accessory structure) of the skin?
Hair, nails and skin glands arise from the epidermis and are skin appendages. The hypodermis is the layer beneath the skin, not an appendage of it.