i want 30 multiple choice questions with their model answer below each question that covers various aspects of the following: The Hair
- It consists of:
a- Shaft: projecting above the surface of the skin.
b- Root: embedded into the skin and consists of:
1- Inner medulla: polyhedral cells with no pigments
and contains soft keratin.
2- Middle cortex: elongated cells with melanin
pigments which give the color of the hair and contains
hard keratin.
3- Outer cuticle: flat cells containing hard keratin.
c- Bulb: the expanded lower end of the hair
responsible of its elongation.d- Hair follicle:
* It is a tubular sheath formed by an epidermal down
growth in which the root of the hair is present.
* The wall of the hair follicle is called root sheath
which is divided into 3 types:
1- Inner root sheath: formed of 3 layers from inside
outwards:
a) Cuticle: flat scales containing soft keratin.
b) Huxley’s layer: formed of 1-3 layers of cubical
cells.
c) Henle’s layer: formed of one layer of elongated
non-nucleated cells.2- Outer root sheath: it is identical with the malpighian
layer of the epidermis.
3- C.T sheath: it is considered part of C.T. of the
dermis and separated from the outer root sheath by a
glassy membrane.The Sweat glands
They are present deep in the dermis.
They are simple coiled tubular glands.
They are two types
1 - Eccrine sweat glands:
They are abundant throughout the dermis of both
thick and thin skin.
Highest concentration in the palms, soles, forehead.
Formed of secretory portion and excretory ductsA- Secretory portion:
Located in deep dermis, Lined by 2 types of cells:
a) Dark cells: Pyramidal cells that line the lumen of
the secretory portion, produce mucous secretion.
b) Clear cells: Located between dark cells, release a
watery secretion.
B- Duct portion:
Lined by stratified cuboidal epithelium
Leaves the secretory portion as a coiled duct, then
becomes straight.
Spirals through the epidermis to deliver sweat to the
outside.2- Apocrine sweat glands:
• It differ from the ordinary eccrine sweat glands
in the following:
Open into the upper part of hair follicles above the
entrance of the sebaceous duct.
Located in axilla, areola, peri-anal and pubic
regions
They secrete after puberty (Due to the effect of sex
hormones).
Despite their name, apocrine they are merocrine
glands.The Sebaceous glands
Simple or branched alveolar glands.
It is a holocrine gland.
Present over most of the body surface except palms
and soles.
Most numerous and most productive on scalp, face
and upper back.
Controlled by androgen hormone.Formed of:
A- Secretory portion:
• Formed of acini embedded in the dermis.
• The acinus is formed of larger cells filled with lipid
vacuoles which degenerate to form an oily product
called sebum.
• Sebum is discharged into the sebaceous duct, which
opens into the upper part of the hair follicle.
• Sebum acts as cream that helps to keep skin soft
preventing its cracking.
B- Duct portion: is lined by stratified squamous
epithelium.The Arrector pili muscles
• Also known as hair erector muscles, they are small
muscles attached to hair follicles.
• Contraction of these muscles causes the hairs to be
in erect position (standing).
• Each arrector pili is composed of a bundle of
smooth muscle fibers.