Skeletal and Integumentary Systems Lecture Questions

What are the layers of thin skin?

Stratum basale, stratum spinosum, stratum granulosum, stratum corneum

What are the layers of thick skin?

Stratum basale, stratum spinosum, stratum granulosum, stratum lucidum, stratum corneum

What is the function(s) of the stratum basale?

anchors the epidermis to the dermal lamina and constantly produces mitotic cells

What type(s) of cells make up the stratum basale?

keratinocytes, melanocytes, and Merkel cells

What is the function(s) of the stratum spinosum?

provides strength, flexibility, and immune defense

How thick is the stratum spinosum?

8-10 cells thick

What type of cells and structures make up the stratum spinosum?

keratinocytes, desmosomes, melanin granules, and Langerhan’s cells

What are desmosomes?

specialized cell structures that firmly bind cells together

What is the function of the stratum granulosum?

a transition zone where living skin cells flatten, die, and form the tough, protective exterior

What are the granules in the stratum granulosum?

keratohyaline granules and lamellar bodies

What are lamellated granules?

lipid products that help the skin stay waterproof

What is the function of lamellated granules?

to prevent water from seeping into the deeper layers of skin

Where are lamellated granules produced?

Smooth endoplasmic reticulum

What type of cells make up the stratum granulosum?

flattened keratinocytes containing keratohyaline

What is the function of the stratum lucidum?

provides an extra layer of protection and waterproofing in thick skin

What type of cells make up the stratum lucidum?

dead, flattened keratinocytes containing eleidin

What is the function of the stratum corneum?

outermost layer of skin that acts as the primary protective barrier

What type of cells make up the stratum corneum?

very thick, dense layer of dead, flattened keratinocytes

How long does it take for the skin to regenerate on average?

about 2 weeks

What other cell types can be found in the epidermis besides the primary layers?

keratinocytes, melanocytes, Langerhans cells, and Merkel cells

What are the layers of the dermis?

Papillary layer and reticular layer

What type of tissue makes up the papillary layer?

loose areolar connective tissue

What fibers can be found in the papillary layer?

collagen and elastic fibers

What structures can be found in the papillary layer?

dermal papillae, thin blood vessels (capillaries), free nerve endings, Meissner’s corpuscles

What is the function of the dermal papillae?

connects the dermis to the epidermis and forms fingerprints during fetal development

What is the function of Meissner’s corpuscle?

perceives fine, light touch

What type of tissue makes up the reticular layer?

dense irregular connective tissue

What fibers can be found in the reticular layer?

elastic and collagen

What makes skin look wrinkly with age?

deterioration of elastic fibers in the reticular layer of the dermis

What is the function of the reticular layer?

the thickest layer of skin (much thicker than the stratum corneum) that provides strength and elasticity

What is the thickest layer of skin?

reticular layer of the dermis

What cells can be found in the dermis?

fibroblasts (collagen and elastin), macrophages, and occasionally mast cells and white blood cells

What accessory structures can be found in the reticular layer?

hair follicles, sweat glands, and sebaceous glands

What kind of tissue(s) is the hypodermis made of?

adipose tissue and areolar connective tissue

What is the function of the hypodermis?

to connect the skin to the fascia of underlying skeletal muscles, store fat/energy, absorb shock, and insulation

What do keratinocytes do?

make up the majority of cells in the epidermis that protect against damage, water loss, UV radiation, and pathogens

Where can keratinocytes be found? (layer)

stratum basale of the epidermis

Which organelle produces keratin?

Ribosomes

How are keratinocytes transported?

new cells form in the stratum basale, forcing them upward towards superficial layers and ultimately the outside of the skin

What is keratin?

a water-insoluble, durable protein that shields cells from physical damage

What cells are primarily affected in a person with squamous cell carcinoma?

The keratinocytes of the stratum spinusoum

What is a carcinoma?

a type of cancer that starts in epithelial tissue

What do melanocytes do?

Produce and distribute melanin

Where can melanocytes be found? (layer)

Stratum basale (epidermis)

Which organelle produces melanin?

Melanosomes inside of melanocytes

What does melanin do?

Absorbs UV radiation, protecting surrounding cells from harmful rays and DNA damage

What are Langerhan’s cells?

 immune cells that live in the epidermis

How do Langerhans cells remove pathogens?

they engulf pathogens through phagocytosis, then travel to lymph nodes through lymphatic vessels

Where can Langerhan’s cells be found? (layer)

all layers of the epidermis, but mostly in the stratum spinosum

Where are Langerhans cells produced?

migration to the skin from the liver during fetal development

What is the function of Merkel cells?

to perceive prolonged fine touch and pressure

Where can Merkel cells be found? (layer)

stratum basale of the epidermis

Where are Merkel cells produced?

stratum basale of the epidermis

What three substances contribute to skin color?

melanin, carotene, and hemoglobin

What does melanin do to the skin?

gives skin its brown pigment, forms freckles and moles, and protects underlying tissues from UV rays

What does hemoglobin do to the skin?

gives skin a pink color due to increased blood flow

What does carotene do?

gives the skin a reddish color due to the breakdown of vitamin A and is especially abundant in the soles of the feet and palms of the hands

How is skin color regulated?

genes tell the melanocytes how much melanin to produce. Everybody has the same amount of melanocytes, skin color depends on how much melanin gets produced

What causes a tan?

UV rays damage the cells of the skin, triggering them to produce more melanin so the skin is more protected from further UV rays

Is tanning positive or negative feedback?

positive feedback

Where are sebaceous glands found? (layer)

in the reticular layer attached to hair follicles

What do sebaceous glands produce?

sebum

What type of gland are sebaceous glands?

holocrine glands

How do sebaceous glands excrete their product?

through holocrine excretion, when the entire cell ruptures to release its product

What are sudoriferous glands?

sweat glands

In what layer can sudoriferous glands be found?

reticular layer of the dermis

What do eccrine glands produce?

watery, nonoderous sweat

How do eccrine glands excrete their product?

through merocrine secretion, where the secretions exit through secretory vesicles in the plasma membrane. This process does not damage the cell

In what layer can eccrine glands be found?

reticular layer of the dermis

Where are eccrine glands found on the body?

soles, palms, forehead, chest, back

What do apocrine glands produce?

 milky, non-odorous sweat

Why are apocrine gland secretions stinky?

bacteria feeds on the cellular matter

How do apocrine glands excrete their product?

through apocrine secretion, where the top of the cell is pinched off so its products can be released. This means the cell has to regenerate part of itself

Where in the body are apocrine sudoriferous glands found?

armpits, groin, mammary projections, and face

In what layer can apocrine glands be found?

reticular layer of the dermis

Where does keratinocyte production for hair begin?

In the basal cells of the hair bulb

What is the medulla of a hair?

the central core

What is the cortex of a hair?

a layer of compressed keratinized cells that are responsible for hair texture (curly, straight, etc.)

What is the cuticle of a hair?

the outer layer of very hard, thick keratinized cells of the hair that do not flake off

How does hair provide protection?

prevents UV damage, keeps particles away from the eyes, and protects other parts from sweat

What are nails?

very hard buildup of very hard keratin that does not flake off

Why do nails look pink?

due to capillaries in the dermis that are visible through the nail

Why do nail colors change?

the keratin on the outside of the nail is sensitive to chemical changes within the body

What does the arrector pili muscle do?

pulls hair follicles up involuntarily and causes goosebumps

What is the bone matrix made out of?

hydroxyapatite (calcium salts), collagen fibers, and cells

What is the ground substance of bone made of?

hydroxyapatite (calcium salts) and collagen fibers

What does hydroxyapatite do for the bones?

allows them to resist compression and gives bones their hardness

What do collagen fibers do for the bones?

resists stretching and twisting, and also provides flexibility and tensile strength

What are osteoblasts?

immature bone cells that form the outer layer by depositing calcium into the matrix

Where are osteoblasts found?

inner and outer surfaces of bone

What are osteoclasts?

large, specialized cells that break down damaged bone cells and releases the calcium into the surrounding blood

What are osteocytes?

mature cells that maintain the bone matrix and ground substance

How are bones classified by texture?

compact bone and spongy bone

What is compact bone?

the dense outer layer of bone that appears smooth and solid

What is spongy bone?

internal bone that is very lightweight and contains needle-like bone projections (called trabeculae) with lots of empty space within

What are trabeculae?

the needle-like bony projections inside spongy bone

What are the classifications of bone by shape?

long, short, flat, sesamoid, irregular

What makes a bone a long bone?

a bone that is longer than it is wide

What bone texture do long bones have?

mostly compact with spongy bone in the epiphyses

What are the long bones of the body?

humerus, radius, ulna, metacarpals, metatarsals, phalanges of the feet and hands, femur, tibia, fibula, and clavicle