Test #2 Anatomy Lecture

ch 4

Define the integumentary system.

The integumentary system is the body system that includes the skin and its accessory structures. It’s the largest organ system in the human body and acts as the body’s first line of defense.

What is the integumentary system composed of?

Skin, hair, nails, sweat glands, sebaceous glands and mammary glands

One of the functions of the integumentary system is to synthesize and store lipids and vitamin D3. True or false

True

The skin is incapable of sensing information from our environment. True or false

False. The skin contains sensory receptors that detect touch, temperature, pain, and pressure.

How does the skin help maintain homeostasis?

The skin helps maintain homeostasis by regulating body temperature (through sweating and vasodilation/vasoconstriction), preventing water loss, and serving as a barrier to pathogens.

What are the two cutaneous membranes (also known as layers)?

The epidermis and the dermis

Exocrine glands are considered accessory structures. True or false

True

Of the two cutaneous membranes, which one is more deep compared to the other?

The dermis is deeper compared to the epidermis

What layer lies deep to the dermis? What is the main component of this layer?

The hypodermis lies deep to the dermis, and it is mainly composed of adipose tissue (adipocytes) and blood vessels.

Name the four main cell types found in the epidermis.

Keratinocytes, melanocytes, Merkel cells, and Langerhans cells

What is the function of keratinocytes vs. merkel cells?

Keratinocytes produce keratin, a protein that provides strength and waterproofing, while Merkel cells function as sensory receptors for touch

Langerhan cells in the epidermis are not considered to be immune cells. True or false.

False. Langerhans cells are immune cells that help defend against pathogens

Name the layers of the epidermis starting from the deepest layer to the most superficial layer.

Stratum basale → Stratum spinosum → Stratum granulosum → Stratum lucidum (only in thick skin) → Stratum corneum

What type of cells are found in the stratum basale?

Basal keratinocytes, melanocytes, and Merkel cells.

What types of cells are found in the stratum spinosum vs the stratum granulosum?

Stratum spinosum: keratinocytes and Langerhans cells. Stratum granulosum: keratinocytes

Describe the stratum lucidum

The stratum lucidum is a thin, clear layer of dead keratinocytes found only in thick skin (palms of the hands and soles of the feet)

What layer is described as the “interlocking layer, dehydrated cells? Is this layer waterproof?

The stratum corneum is the interlocking layer of dehydrated cells. Yes, it is relatively waterproof due to keratin and lipid secretions

Do all layers of the epidermis contain keratinocytes?

Yes, all layers of the epidermis contain keratinocytes

The dermis consists of two sublayers. Name the layers. In addition, describe which is more superficial of the two and which layer is more abundant between the two

The two layers are the papillary layer and the reticular layer. The papillary layer is more superficial, while the reticular layer is deeper and more abundant.

Does the papillary layer of the dermis contain blood vessels and axons? What is the general function of this layer?

Yes, the papillary layer contains blood vessels and axons. Its function is to provide nutrients to the epidermis and support sensory perception. It also helps anchor the skin layers together, and it helps regulate skin temperature.

Areolar connective tissue is found in the papillary layer of the dermis. True or false

True

What glands are found in the reticular layer? What kind of glands are these?

Sweat glands (apocrine and eccrine) and sebaceous glands are found in the reticular layer. These are exocrine glands.

Name two functions of the hypodermis.

Its key functions include providing insulation, storing energy, and cushioning the body to protect internal structures.

Name two functions of hair

Hair provides protection (e.g., from UV radiation, particles entering the eyes/nose) and helps with sensation through associated nerve endings

Describe two functions of the exocrine glands found in the reticular layer of the dermis

Exocrine glands in the reticular dermis help the body by (1) regulating temperature through sweat and (2) protecting and lubricating the skin and hair with oil.

Name two subtypes of sweat glands

Apocrine glands and eccrine glands.

Name two special apocrine glands

Both ceruminous and mammary glands are modified apocrine glands with highly specialized secretions adapted for protection (earwax) or nutrition (milk).

What type of substance do apocrine sweat glands produce?

They produce a thicker, milky secretion that becomes odorous when metabolized by skin bacteria.

How are ceruminous glands different from mammary glands?

Ceruminous glands produce earwax (cerumen), while mammary glands produce milk

Mammary glands are examples of eccrine sweat glands. True or false.

False. Mammary glands are specialized apocrine glands.

What type of substance do eccrine sweat glands produce?

They produce a watery secretion (sweat) primarily composed of water, salts, and waste products.

Where are eccrine sweat glands located? Is it the same for apocrine glands?

Eccrine sweat glands are located all over the body, especially on the palms, soles, and forehead. In contrast, apocrine glands are limited to areas like the armpits, groin, and around nipples

What type of substance do sebaceous glands produce? Are sebaceous glands exocrine glands? Are sebaceous glands a type of apocrine glands?

Sebaceous glands produce sebum (an oily substance) and yes, they are exocrine glands

What protein is found in nails?

Keratin

What type of glands are mammary glands?

Mammary glands are specialized apocrine glands; you can also say they are exocrine glands.

What is the function of mammary glands?

The primary function is milk production (lactation) to nourish babies.

What is the skeletal system made up of?

Skeletal bones, cartilage, ligaments, and connective tissue to stabilize the skeleton.

What is the function of osseous tissue?

Support – provides a framework for the body.

Mineral storage – stores calcium, phosphate, and other essential minerals.

Blood cell production – houses red bone marrow for hematopoiesis.

Leverage – enables movement by acting with muscles and joints.

Protection – shields vital organs such as the brain, heart, and lungs.

Where is the majority of the calcium stored in the body?

In the bones

What component makes up the majority of bone mass?

Calcium phosphate (in the form of hydroxyapatite crystals)

Provide three examples of bone shapes and an example of each.

Long bone (femur), flat bone (sternum), irregular bone (vertebra), sesamoid bone (patella)

Osseous tissue (skeletal system) is able to produce red blood cells. True or false.

True

Describe the composition of osseous tissue? Provide a breakdown (a percentage) of each component.

Bone matrix makes up about 98% of bone mass which includes: Hydroxyapatite (~66%) – a mineral made of calcium and phosphate that provides hardness and strength and Collagen fibers (~33%) – which provide flexibility and tensile strength.

Bone cells (~2%) make up only a small fraction of bone mass.

What are the four types of bone cells?

Osteoblasts, osteocytes, osteoclasts, and osteoprogenitor cells.

What bone cell maintains bone tissue?

Osteocytes

What is the function of osteoblast and osteoclast?

Osteoblasts build bone, osteoclasts break down bone.

If osteogenesis was taking place, what bone cells would you expect to be the most active?

Osteoblasts and osteoprogenitor cells.

What type of cell is heavily involved in bone repair after a break?

Osteoblasts and osteoprogenitor cells.

What is osteolysis?

The breakdown of bone matrix by osteoclasts to release minerals such as calcium and phosphate ions.

What layer surrounds the medullary cavity?

The endosteum

What are the bony plates found in spongy bones called?

The bony plates found in spongy bone are called trabeculae.

They are thin, branching plates of bone that form an open, lattice-like network. Trabeculae help reduce the overall weight of the bone while still providing structural support, and the spaces between them are often filled with red or yellow bone marrow.

The ends of long bones are called diaphysis. True or false.

False. The ends are called epiphysis; the shaft is the diaphysis.

What type of bone forms the walls of bone?

Compact bone

What type of bone is abundant at the ends of bone (epiphysis)?

Spongy bone (cancellous bone).

What layer is superficial to compact bone?

The periosteum.

The functional unit of spongy bone are osteons. True or false.

False. The functional units of spongy bone are trabeculae.

What is the difference between the central canal and perforating canals?

Central (Haversian) canals run longitudinally through osteons (up to down); perforating canals (Volkmann’s canals) run perpendicular and connect central canals.

Define lamellae.

Concentric rings of bone matrix. The three types of lamellae include: Concentric lamellae, Interstitial lamellae and Circumferential lamellae

What is the function of lacunae and canaliculi?

Lacunae house osteocytes; canaliculi are canals that allow exchange of nutrients and waste between osteocytes.

What are the major sections of a typical long bone?

Diaphysis, epiphysis, metaphysis

The medullary cavity of the diaphysis consists of what type of bone marrow?

Yellow bone marrow (in adults) and red bone marrow (in children).

What is the function of articular cartilage?

It reduces friction and absorbs shock at joints.

What is the difference between red bone marrow and yellow bone marrow?

Red marrow produces blood cells; yellow marrow stores fat.

Which bone marrow is more abundant in adults?

Yellow bone marrow

The periosteum and endosteum are connective tissue layers associated with bones, but they differ in location and function. Describe these differences for each layer.

Periosteum covers the outer surface of bones and serves as protection and attachment for tendons/ligaments; endosteum lines the medullary cavity and trabeculae of spongy bone and functions to provide bone growth and remodeling . Both contain osteogenic cells.

Eight weeks into development, what is the skeletal system, primarily made up of?

Hyaline cartilage

Bone formed from cartilage is called intramembranous ossification. True or false.

False. Bone formed from cartilage is endochondral ossification.

What tissue do intramembranous ossification and endochondral ossification come from?

Both processes originate from mesenchymal tissue.