Anatomy Ch. 5 Quiz 2

Sebum

-lubricates the surface of the skin and hair -consists of cell fragments and fatty substances -in excess may cause seborrhea

2 types of sweat glands

1.) eccrine glands 2.) apocrine glands

Epidermal derivatives

1.) hair 2.) sweat gland 3.) sebaceous gland

Advantages of hair keratin

1.) it is tougher and more durable 2.) it's individual cells don't flake off

3 concentric layers of keratinized cells

1.) medulla (center)- consists of large cells and air spaces. It is absent in fine hairs. 2.) cortex- a bulky layer surrounding the medulla, consists of several layers of flattened cells 3.) cuticle- outer-most formed from a single layer of cells that over lap one another from below like shingles on a roof

Functions of sebaceous glands

1.) secretes into a hair follicle 2.) softens and lubricates the hair and skin 3.) prevents hair from becoming brittle 4.) slows water loss from the skin when the external humidity is low

Functions of hair

1.) sense insects on the skin before they bite or sting us 2.) hair on the scalp guards the head against physical trauma, heat loss, and sunlight 3.) eyelashes shields the eyes 4.) nose hairs filter large particles

Sweat Glands

A.K.A. Sudoriferous glands, distrkbutes over the entire skin surface except parts of the external genitalla.

Eccrine glands

Also called merocrine sweat glands, are far more numerous and are particularly abundant on the palms, soles of the feet, and forehead.

Mammary glands

Another variety of specialized sweat glands, secrete milk.

Apocrine glands

Approximately 2,000 of them and are largely confined to the auxiliary and anogenital areas. -ceruminous glands: modified apocrine glands found in lining of the external ear canal.

Arrector pili

Associated with each hair follicle, it is the bundle of smooth muscle cells

Vellus hair

Body hair of children and adult females that is pale and fine

Arrector pili muscle

Can cause a hair to stand up straight

Terminal hair

Coarser, longer hair of the eyebrows and scalp, may be darker

The rules of nines is helpful clinically in:

Estimating the extent of a burn

Hairs (pili)

Flexible strands produced by hair follicles and consist largely of dead, keratinized cells.

What is the difference between heat-induced sweating and a "cold sweat", and which variety of sweat glands is involved?

Heat-induced sweating occurs all over the body when we are over-heated. A cold sweat is emotionally induced sweating that begins on the palms, soles, and armpits and then spreads to other body areas. Both types of sweating are produced by the eccrine sweat glands, but activity of apocrine sweat glands is also likely during a cold sweat.

When Anthony returned home from a run in 85 degree weather, his face was dripping with sweat. Why?

His sympathetic nervous system activated his eccrine sweat glands and caused heat-induced sweating in order to cool the body.

Apocrine gland

Includes protein and lipid substances that become odoriferous as a result of bacterial action

Why are nails so hard?

Nails are hard because the keratin they contain is the hard keratin variety.

Influence of hair growth

Nutrition and hormones

Sebum

Oily secretion of sebaceous glands

Sebaceous (Oil) Glands

Simple branched alveolar glands that are found all over the body except in the thick skin of the palms and soles.

What is the role of an arrector pili muscle?

The arrector pili muscles pull the hair to the upright position

What is the function of the hair papilla?

The hair papilla contains a knot of capillaries that supplies nutrients to cells of the hair bulb.

Sebaceous glands are not found in thick skin. Why is their absence in those body regions desirable?

The palms of the hands and soles of the feet are thick skin areas. It would be dangerous to have oily soles, and oily palms would decrease the ability of the hands to hang onto things.

Why is having your hair cut painless?

There are no nerves in a hair, so cutting hair is painless.