BSCI 201 exam 2 review

Integumentary 1. Name and describe all the strata in the epidermis of thin skin and thick skin.

Thin: corneum (dead cells that have keratin surrounded by lipids) / granulosum (keratohyalin and hard protein envelope) / spinosum (accumulation of keratin fibers and lamellar bodies) / basale (deepest layer; mitosis here).

Thick: includes lucidum (dead cells containing keratohyalin; then a translucent layer of dead cells that thickens the epidermis) + the 4 other strata.

Integumentary 2. Describe the following: tonofilaments; Langerhans cells; lamellated granules; keratohyalin granules; melanocytes

Tonofilaments: intermediate filaments that resist tension placed on the skin.

Keratohyalin granules: contain keratin; making the epidermis tough and abrasive. Lamellated granules: contain glycolipids (makes the epidermis waterproof).

Langerhans' cells: epidermal dendritic cells; engulf and digest pathogens. Melanocytes: secrete brown/black pigment called melanin.

Integumentary 3. Name and describe the two layers in the dermis

Papillary layer: composed of areolar CT; has papillae and Meissner's corpuscles (touch receptors).

Reticular layer: composed of dense irregular CT; contains touch receptors (Pacinian corpuscles) for deep pressure.

Integumentary 4. Discuss three differences between thin skin and thick skin

Thin: 4 strata; 0.5mm thick and covers most of the body; no ridges.

Thick: 5 strata; up to 4mm thick and only on the palms/soles; dermal ridges under papillae forming epidermal ridges.

Integumentary 5. What are epidermal ridges? Discuss the basis for fingerprinting. What is the significance of cleavage lines?

Epidermal ridges: increase friction and enhance gripping; byproduct of papillae on the surface of thick skin; supported by mounds called dermal ridges.

Patterns of epidermal ridges are genetically unique to everyone (basis of fingerprinting).

Cleavage lines: areas of the reticular layer with fewer collagen bundles; surgeons make incisions parallel to them for better healing.

Integumentary 6. Describe the following: Meissner's corpuscles; Pacinian corpuscles; Merkel discs

Meissner's corpuscles: touch receptors in the papillary layer of the dermis.

Pacinian corpuscles: respond to deep pressure placed on the skin; located in the reticular layer.

Merkel discs: at the epidermal-dermal junction; act as a light touch receptor.

Integumentary 7. Name and discuss the functions of the accessory skin structures.

All derived from the stratum basale of the epidermis but are in the dermis where they get nutrients.

Sweat (sudoriferous) glands: simple coiled tubular multicellular exocrine glands; pH 4-6;

Eccrine (merocrine): 3 million per person; abundant in palms/soles/forehead; secrete sweat for thermoregulation when body temp rises; merocrine secretion.

Apocrine: anogenital and axillary areas; active after puberty (sex steroid hormones); secrete viscous yellowish fluid onto hair follicles; merocrine secretion; odoriferous glands associated with body odor.

Specialized: ceruminous glands (external ear canal; secrete cerumen/earwax) and mammary glands (breast; secrete milk).

Sebaceous (oil) glands: simple branched alveolar multicellular exocrine glands; everywhere except palms/soles; secrete sebum via hair follicles and pores; holocrine secretion.

Hair (pili)/follicles: produced by cells in the matrix inside hair follicles; shaft (above skin) and root (below skin enclosed by follicle);

thermoregulation/insulation; arrector pili muscles pull hair upright (goosebumps) trapping air to prevent heat loss.

Nails: tightly packed keratinized epidermal cells; protect ends of fingers from trauma; help with grasping objects and scratching.

Integumentary 8. What is the acid mantle?

Combination of the acidic pH of sweat and dermicidin on the surface of skin to retard microbial growth.

Integumentary 9. Discuss the thermoregulatory function of the integumentary system

Hot weather: sweat is 99% water and has a high heat of vaporization; heat from the body is used to evaporate the water from the skin surface, dropping the temp back to normal. Cold weather: arrector pili muscles make the hairs stand up and the skin dimple, trapping a layer of air that insulates the body and keeps it warm.

Integumentary 9. The integumentary system provides protection: discuss how it provides a) physical protection b) biological protection c) chemical protection

Physical: skin is a physical barrier against abrasion/water loss/foreign objects; e.g., the stratum corneum is tough and waterproof and is constantly replaced as old cells shed.

Biological: the epidermis keeps most microbes from entering the body; Langerhans' cells in the stratum spinosum digest pathogens; sweat contains dermicidin (antimicrobial).

Chemical: the acid mantle with a pH of 4-6 and dermicidin keep microbial growth down; melanocytes protect against UV radiation; glycolipids and keratin make the epidermis waterproof and chemically tough.

Integumentary 10. Name and describe the 3 types of burns; which type/s of burns are associated with pain? What are the risk factors associated with third-degree burns?

3rd degree: epidermis only (sunburn); the area hurts to the touch and can heal on its own in 3-4 days.

2nd degree: papillary layer (blisters); hurts to touch and can heal on its own unless it gets infected.

1st degree: doesn't hurt because nerves are destroyed (the area around the burn in a 2nd-degree burn hurts). Prone to infection and dehydration due to the corneum (waterproof and abrasion-proof layer) being destroyed.

Integumentary 11. Name and define the 3 major types of skin cancer; which type is the most common type of skin cancer and why?

Basal cell carcinoma: highly mitotic and easy to mutate; abnormal keratinocytes in the stratum basale; grows slowly.

Squamous cell carcinoma: cells in the stratum spinosum; grows rapidly.

Melanoma: very rare; most aggressive form; resistant to chemo and likely to spread; proliferation of melanocytes.

Integumentary 12. Explain why albinos are more susceptible to developing skin cancer

No melanin to protect from the sun; which equals sun damage.

Skeletal 1. Compare and contrast compact bone tissue and spongy bone tissue.

Compact bone: made of osteons; covered by periosteum.

Spongy bone: made of trabeculae; covered by a thin layer of compact bone.

Skeletal 2. Name and describe the 4 structural classes of bones: Give an example of each class.

Long: humerus/femur. Short: carpals/tarsals. Flat: sternum. Irregular: coccyx/vertebra.

Skeletal 3. Discuss the differences between the child long bone and the adult long bone

Adult: yellow bone marrow in the medullary cavity; plates have ossified (epiphyseal plate closure), leaving an epiphyseal line, Lengthening has stopped, so height is fixed

Child: red bone marrow in the medullary cavity; epiphyseal plates (hyaline cartilage) are present at the epiphyseal-diaphyseal junctions (metaphyses), Bone can still lengthen, because new cartilage is added on the epiphyseal face and replaced by bone on the diaphyseal face

Skeletal 4. Define: diaphysis

Shaft of long bone covered by thick collar of compact bone.

Skeletal 4. Define: epiphysis

Expanded end of long bones.

Skeletal 4. Define: medullary cavity

Contains red bone marrow in childhood and yellow bone marrow in adulthood.

Skeletal 4. Define: periosteum

Double layered; composed of outer fibrous layer (dense irregular connective tissue) and inner osteogenic layer (contains osteoblasts/clasts).

Skeletal 4. Define: endosteum

Covers internal surfaces of bones; contains osteoblasts/clasts.

Skeletal 4. Define: Sharpey's fibers

Attach periosteum to compact bone.

Skeletal 4. Define: osteons

Structural units of compact bone.

Skeletal 4. Define: canaliculi

Tiny canals that connect lacunae and allow the Haversian canal to transfer substances.

Skeletal 4. Define: lamellae

Elongated cylindrical tubes where osteons reside.

Skeletal 4. Define: Haversian canal

Central canal that runs in the core of each osteon.

Skeletal 4. Define: perforating/Volkmann's canals

Connect blood vessels and nerves between the periosteum and Haversian canals.

Skeletal 4. Define: lacunae

Shallow cavities in solid bone matrix that house osteocytes.

Skeletal 5. Name and compare the 2 types of prenatal ossification. What are membrane bones? What are endochondral bones?

Intramembranous ossification: develops from fibrous connective tissue membrane (derived from mesenchyme); results in membrane bones = the cranial bones and clavicles (most membrane bones are flat bones).

Endochondral ossification: derived from hyaline cartilage and produced by chondroblasts (which derive from mesenchyme); bones that come from this are endochondral or cartilage bones = every bone except the cranial bones and clavicles.

Skeletal 8. What is bone remodeling and what is the purpose of bone remodeling? Give the function of osteoblasts and osteoclasts in bone remodeling

Too many osteoclasts = osteoporosis.

Skeletal 10. State Wolff's Law. Discuss three examples where this law is applicable or supported

Bones grow and change based off the stressors placed on them.

OR

Bones remodel and grow in response to the mechanical stresses placed on them. Bone gets thicker and stronger where it is stressed, and it loses density where it isn’t.