Anatomy - Quiz #2

The integumentary system, meiosis, genetics

What’s an organ?

tissues working together to perform certain functions

How much does the skin take up total body weight?

7%

The skin varies in thickness from …?

1.5 - 4 mm

What are the two distinct regions of the skin?

1) epidermis (thick epithelium)

2) dermis (fibrous connective tissue)

Where are the skin layers firmly cemented together? Separation of the layers leads to what?

Undulating border and separation leads to blisters

What are the functions of the skin?

Protects the body from bumps, scrapes, and cuts; Screens out harmful UV rays from the sun; Metabolic duties (synthesis of vitamin D); Insulates/cushions underlying body tissues; Protects the body from water loss; Helps regulate body temp; Excretes wastes (urea, salt); Contains sense organs

What are the four distinct cell types in the epidermis?

1) Keratinocytes 2) Melanocytes 3) Merkel cells 4) Langerhans’ cells

What are the layers of the epidermis from deep to superficial?

Stratum basale → Stratum spinosum → Stratum granulosum → Stratum lucidum → Stratum corneum

What are keratinocytes?

they are cells that produce keratin and produce antibiotics and enzymes that detoxify harmful chemicals

What type of cell is the most distinct in the epidermis?

Keratinocytes

What is keratin?

a tough fibrous protein that gives the epidermis its protective

What cell is connected to one another by desmosomes?

Keratinocytes

What are melanocytes?

spider shaped cell that make the dark skin pigment melanin

What does melanocytes do to keratinocytes?

they transfer there melanin to keratinocytes where it clusters on the superficial side of the cell

Why is it important that keratinocytes have clusters of melanin on their superficial side?

Because the sun is shinning its UV ray lights on top of the skin

What happens to melanin in light skinned people?

it gets digested by lysosomes a short distance above the basal layer

What happens to melanin in dark skinned people?

no digestion occurs and melanin occupies keratinocytes throughout the epidermis

What layer(s) is keratinocytes located?

Stratum basale to Stratum granulosum

What layer(s) is melanocytes located?

Stratum basale

What are Merkel cells?

they are hemisphere-shaped cells that are associated with a disc-like sensory nerve ending and serves as a receptor for touch

What layer(s) is Merkel cells located?

Stratum basale

What are Langerhans’ cells and what do they do?

they are a class of macrophages-like cells and part of the immune system. They police the outer body surface, using receptor mediated endocytosis to take up proteins/antigens that have invaded the epidermis

Can Langerhans cell leave the cell? If they can, why?

Yes, they travel to nearby lymph node, where they present the antigens to killer T lymphocytes that attack all foreign cells that carry the antigen

What is the stratum basale layer?

its the deepest epidermal layer; it is consists of a single row of cells (stem cells); cells rapidly divide via mitosis

What is the stratum spinosum layer?

its several layers thick; mitosis also occurs here but less than basale; contains thick bundles of intermediate filaments = tonofilaments

What is the stratum granulosum layer?

its 1 to 5 layers of flattened keratinocytes with keratohyaline granules and lamellate granules

What do keratohyaline granules do?

form keratin in the higher strata

What do lamellated granules do?

contain a waterproofing glycolipid that is secreted into the extracellular space and plays a role in slowing water loss

What is the stratum lucidum layer?

occurs only in thick skin; consists of a few rows of flat dead keratinocytes

What is the stratum corneum layer?

the most external part of epidermis; composed of dead keratinocytes; the keratin and thickened plasma membrane of cells protect the skin against abrasion and penetration

Do you know how much skin a person sheds in a lifetime?

40 pounds

What is the dermis?

the second major layer of the skin; strong and flexible connective tissue

What is the other name for dermis?

Hide

What does the dermis do?

it binds the entire body together

What are the vascular plexuses that make up the dermal blood vessels?

Cutaneous plexus (deep) and Subpapillary plexus (superficial)

What is the Cutaneous plexus?

a vascular plexus that is located between the hypodermis and the dermis

nourishes the hypodermis and the structures located within the deeper portions of the dermis

What is the subpapillary plexus?

a vascular plexus that is located below the dermal papillae

supplies the dermal papillae and epidermis

What is the function of vascular plexuses ?

It plays a role in thermal regulation

What are the layers of the dermis?

1) papillary layer 2) reticular layer

What is the papillary layer?

the first layer of the dermis that is superficial and 20% of its thickness; its composed of areolar connective tissue; it has the dermal papillae

What is the dermal papillae?

fingerlike projections that extend into the overlying epidermis

What happens to the dermal papillae on the palms and soles?

they lie atop of larger mounds (dermal ridges), which elevate the overlying epidermis into epidermal ridges

What creates fingerprints?

when sweat pores along the crests of the epidermal ridges

What functions do epidermal ridges provide?

they increase friction and enhance gripping ability of the hands and feet

What is the reticular layer? Its a network of what?

the second layer that is deep and 80% thickness of the dermis; composed of dense irregular connective tissue

A network of collagen fibers

What are the fibers in the reticular layer and what do they do?

Collagen fibers: gives skin its strength and resilience

Elastic fibers: provide the skin with stretch-recoil properties

What can extreme stretching of the skin do?

can tear the collagen in the dermis → causes slivery white scars = striae

Is the hypodermis part of the skin?

No

What are the other names for the hypodermis?

Superficial fascia and subcutaneous layer

What is the hypodermis?

a layer deep to skin and made up of more areolar than adipose connective tissue that anchors skin to underlying structures

What is the function of the hypodermis?

help insulate the body by preventing heat loss with fat storage

Does the hypodermis thicken with weight, if so where on the female and male body?

Yes. For females subcutaneous fat thickens at the thighs and breasts and for male in their abdomen

What are the three pigments that contribute to skin color?

1) melanin 2) carotene 3) hemoglobin

What is melanin?

made from an amino acid = tyrosine

present as yellow, reddish, brown, black

its made in melanocytes that contain an enzyme = tyrosinase

What are freckles and moles?

localized accumulation of melanin

where are freckles located and how are they formed?

they are melanin in basal layer of epidermis and form as the result of exposure to the sun

How are moles formed and where are they located on the skin?

they are clusters of melanocytes transform into melanin-containing cells and are in the basale layer of epidermis and top of the dermis

What is carotene?

a yellow-orange pigment the body obtains from vegetable like carrots and tomatoes

its in the stratum corneum of the epidermis and in fat of the hypodermis

How is hemoglobin a pigment to skin color?

by its crimson-color of oxygenated hemoglobin

Whats another factor of skin color besides the main three? How is it produced?

Vitamin D; a hormone required for calcium absorption

It is produced when UV rays stimulate the deep epidermis

What are the two cutaneous glands?

1) subaceous glands 2) sweat glands

Where are sebaceous glands and what is the structure of it?

they are associated with a hair follicle and are over the entire body except palms and soles

The structure of it is simple alveolar glands with several alveoli that are filled with cells that make up oily lipids

What does the sebaceous gland secrete?

an oily substance what acts as lubricant to keep skin soft and moist and hair from being brittle, collects dirt, prevents water loss and kill bacteria

When are the sebaceous glands active?

during puberty by being activated by hormones/androgen

What are blackheads and acne?

they are accumulations of dried sebum and bacteria in the oil duct;

an active infection of the subaceous gland

What process is used for to make sebum?

Holocrine secretion is used to break up the cell into products

Where are the sweat glands and what does it do?

it is widely distributed on body; secrete sweat which is a blood filtrate

How is sweat released?

through exocytosis

How much sweat do we normally produce in one day? and on hot days?

500 mL; 12L

What do only mammals use sweat glands for?

thermoregulation

Why are humans less hairy compared to other mammals?

Because hair interferes with evaporation of sweat and ability to cool down

what is sweat?

a filtrate of blood that passes through the secretory cells of sweat glands

what is true sweat composed of?

99% of water and 1% salts (NaCl) and metabolic wastes (urea, ammoina, uric acids)

What are the two types of sweat glands?

a) eccrine b) apocrine

which type of sweat glands produces true sweat?

Eccrine glands

Where are the eccrine glands and what is the structure?

they are on palms, soles, and forehead

they are coiled simple tubular gland and secretory base is in the deep dermis and hypodermis

Where are the apocrine glands and what is the structure?

they are in axillary, anal, and genital areas

milky or yellow color sweat made of fatty substances and proteins

When do apocrine glands start to function? what happens to them for woman?

at puberty because of androgens; they enlarge and recede during phases of menstrual cycle

What are Hair and hair follicles?

Hair: long filaments

Hair follicles: tubular invagination of the epidermis from where hair grow

For humans what is the function of hair?

main function: to sense things that lightly touch the skin

the hair on scalp protects against direct sunlight and heat loss on cold days

eyelashes shields eyes and nose hairs filter large particles (insects and lint)

What is hair composed of?

dead keratinized cells

Whats the advantage of hard keratin vs soft keratin?

1) it is tough and more durable

2) the cells of hard keratin do not flake off

The chief parts of hair are ?

1) root = hair embedded in skin 2) shaft= projects above skin

What are the three concentric layers of keratinized cells in hair are?

1) medulla 2) cortex 3) cuticle

What is the medulla?

the central core of the hair that consists of large cells and air spaces

What is cortex?

its surrounds medulla that consists of several layers of flattened cells

What is the cuticle?

its the outmost layer of the hair that consists of a single layer of cells that overlap one another

What happens when you get split ends?

the outer layer/ cuticle gets worn down by an abrasion and the keratin fibrils in the cortex and medulla to frizz out

What is hair pigment made of?

melanocytes at the base of the hair follicle and transferred to hair root

How do you get gray/white hair?

decrease in the production of melanin and melanin gets replaced by colorless air bubbles in the hair shaft

What is a hair bulb and root plexus?

deep, expanded end of hair follicle

knot of sensory nerves around hair bulb

What is the wall of hair follicle composed of?

outer layer = connective tissue root sheath (from dermis)

inner layer = epithelial root sheath (from epidermis)

What is the arrector pili muscle?

its a bundle of smooth muscle that runs from the most superficial part of the dermis to a deep lying hair follicle

What are the three things nail is made of?

a) distal free edge b) a body c) a proximal root

What does the nail rests on?

it rests on a bed of epidermis = nail bed. It contains deeper layers of the epidermis

Why do nails look pink?

because of the rich network of capillaries in the underlying dermis

What is the nail matrix?

thick bed at the root at the proximal end of the nail body

What is the lunula?

the white crescent at the root of the nail body

What are nail folds?

lateral and proximal borders of the nail that’s overlapped by skin folds

What is the eponychium (cuticle)?

the proximal nail fold