Chapter 12(mammalian Skin) Flashcards
What is skin?
The outer body covering of vertebrates (animals with backbones).
Functions of skin:
- Protection
- Temperature regulation
- Sensation
- Excretion
The skins the largest organ with a weight of
4.5-5kg
What are the layers of the skin ?
the epidermis and the dermis.
What is the upper or outer layer of the skin.
Epidermis
_____ is a tough, waterproof, protective layer
The epidermis
What provides the skin with strength and elasticity ?
Dermis
What is the thin layer anchoring the epidermis and dermis?
Basement membrane
The basement membrane is made up of
a series of elaborately interconnecting molecules that act as ropes and grappling hooks to hold the skin together.
The subcutaneous layer is composed of
protein fibres and adipose tissue (fat).
What Make up 90% of the epidermis?
Keratinocytes
Keratinocytes Produce;
keratin, a tough protein that protects the skin
______ Produce melanin, the pigment that gives skin its color
Melanocytes
What Protect the DNA of keratinocytes from sun damage?
melanosomes
packets of melanin are called
melanosomes
Difference in skin tone is because of the
variations in melanin production and distribution.
melanin sometimes accumulates in patches, forming ____
freckles, age spots, or liver spots.
what makes redheaded people more sensitive to the sun?
pheomelanin
What is albinism,
A total lack of melanin, a genetic condition
The epidermis is composed of what cells?
Keratinocytes
Melanocytes
Langerhans cells
Merkel cells:
What are the Langerhans cells of the skin?
Part of the immune system, recognize and fight off harmful substances.
Where are langerhans cell produced
Bone marrow
What is merkel cell of the epidermis?
Touch receptors located in sensitive areas like fingertips.
Where does Strength, Sensation, and Temperature Regulation Meet?
Dermis
the dermis or lower layer of the skin is richly supplied with
blood vessels and sensory nerve endings.
The dermis is composed of
Primarily made of collagen and elastin fibers, with fewer cells compared to the epidermis.
The main structural component of the dermis is a protein called_____
collagen
Bundles of collagen molecules pack together throughout the dermis, accounting for ______ of the dry weight of skin.
three-fourth
Collagen is responsible for
The skin’s strength
Elastin is responsible for
The skin’s elasticity
What are the Cells that produce collagen and elastin.
Fibroblast
What are the layer of the dermis
Contains two layers: the papillary layer (upper) and the reticular layer (lower).
the reticular layer. It is made primarily of
coarse collagen and elastic fibres.
glands and hair follicles are often anchored in
the reticular layer of the dermis.
_____ contains several different types of sensory receptors
The reticular layer
_____ are receptors found in the deep dermis of weight-bearing surfaces,
Pacinian corpuscles
What are skin appendages?
Structures like hair, nails, and glands embedded within the skin.
Scalp hair grows at about
1mm every 3 days.
the visible part of the hair is called
shaft
Where does hairs grow from ?
Grows from follicles, with the bulb at the base nourishing it.
Hair is composed primarily of.
keratin
At the base of the follicle is the bulb, which contains
cells that give rise to the keratinocytes that make up the hair, as well as blood vessels that nourish the growing hair.
The colour of hair is due to____,
melanin
Dark hair contains
true melanin
blond and red hair result from?
types of melanin that contain sulphur and iron
Hair goes grey when ___
melanocytes age and lose the enzyme necessary to produce melanin.
White hair occurs when
air bubbles become incorporated into the growing hair.
The texture of hair results from
the shape of the hair shaft.
Straight hair appears ____ in cross section,
round
wavy hair has an ____ in cross section,
oval shape
curly hair has _____ appearance.
An elliptical or kidney-shaped
Function of the finger mail
- Protect fingertips and toes from injury.
- Aid in grasping small objects.
- Enable scratching.
Nails on the fingers and toes are made of
hard, keratin-filled epidermal cells.
The part of the nail that is visible is called
the nail body,
the portion of the nail body that extends past the end of the digit is called
the free edge.
White, crescent-shaped area at the base, lacking blood vessels and covered by thicker epidermis is called
Lunula
The part of the nail buried under the skin
Mail root
where are the nail cells are produced.
The nail root
Fingernails typically grow _____ per week.
1 mm (0.04 in)
What is the Eccrine sweat gland?
Most numerous, found almost everywhere (especially palms and soles).
_______ sweat gland Secrete watery sweat for cooling and waste removal.
Eccrine
_______ sweat gland secrete milky fluid potentially involved in sexual attraction.
What are apocrine
Sebaceous glands are found
all over the body except on the palms, the soles, and the top of the feet.
Sebaceous produce an oily substance called,
sebum
Function of the sebum
keeps the Skin and hair from drying out and inhibits the growth of certain harmful bacteria.
_____ are modified sweat glands found in the ears
ceruminous, glands
The ceruminous gland secrete
a waxy substance that helps prevent foreign particles from entering the ear.
