Exam 2 - BIOL111 Lecture

Study Guide for Exam 2

epidermis layers

epidermis layers

deep to superficial

basale →spinosum → granulosum → lucidum →corneum

stratum basale

• deepest (1st) layer

• single layer of actively dividing cells

• older cells pushed towards surface

• melanocytes present

stratum spinosum

• 2nd layer

• “spiny” appearance, due to desmosomes between cells

• melanin covers DNA in nuclei to protect against UV damage

stratum granulosum

• 3rd layer

• keratin

• cells flatten and die

stratum lucidum

• 4th layer

• clear layer

• found only in thick skin on palms and soles

• flattened, dead keratinocytes

stratum corneum

• 5th & outermost layer

• makes up most of the epidermal thickness

• many layers of dead flattened cells that shed regularly

• keratin protects skin from abrasion and penetration

• "waterproofing”

hair shaft

the part that projects above the skin surface

hair root

the part embedded in the skin

arrector pili

causes the hair to stand erect

medulla

central core of hair; contains soft keratin

cortex

several layers of flattened cells that surrounds the medulla of the hair

cuticle

outermost single layer of overlapping cells of the hair

hair pigment

made from melanocytes and pigment transferred to cortical cells

glands

sebaceous and apocrine sweat _____ empty secretions into hair follicle

basal cell carcinoma

• most common form of skin cancer; slow-growing

• Excellent cure rate

• Affects cells of the stratum basale

• Found on sun-exposed areas of the skin

• Associated with long term exposure to UV radiation (e.g. sunlight, tanning beds); fair skin, family history, age

• Appearance: a pearly white, skin-colored or pink bump; it may rupture, bleed and scab over

squamous cell carcinoma

• also common form of skin cancer; grows rapidly

• Affects keratinocytes of stratum spinosum 

• Found most often on head and hands

• Usually not life-threatening, but can be aggressive and metastasize

• Associated with long-term exposure to UV radiation, fair skin, history of sunburns, weakened immune system, family history

• Appearance: firm red nodule, or flat, scaly, reddened patch

melanoma

• most fatal skin cancer

• Proliferation of melanocytes

• Rapid growth and high rate of metastasis

• Poor cure rate 

  1. Chemotherapy resistance

  2. Metastasis 

  3. Late detection (lesion > 4 mm thickness)

• Spreading brown-black patch

• Risk factors include: fair skin, history of exposure to UV radiation, sunburns, living near equator, having a large number of moles over the body

ABCDEs of melanoma

1. A is for asymmetrical shape. Look for moles with irregular shapes, such as two very different-looking halves.

2. B is for irregular borders. Look for moles with irregular, notched or scalloped borders.

3. C is for changes in color. Look for growths that have many colors or an uneven distribution of color.

4. D is for diameter. Look for new growth in a mole larger than 1/4 inch (about 6 millimeters).

5. E is for evolving. Look for changes over time, such as a mole that grows in size or that changes color or shape. Moles may also evolve to develop new signs and symptoms, such as new itchiness or bleeding

prevention

• limit sun exposure

  1. avoid strongest rays (between 10AM-2PM)

  2. wear long sleeves/hats/long pants

• use sunscreen of at least SPF 15 and apply regularly

• regularly examine skin for any changes

sudoriferous glands

• eccrine — involved in thermoregulation, excretion

• apocrine — scent glands, and their secretions usually have an odor

(sweat)

eccrine gland

• involved in thermoregulation, excretion

• found over most of the body (numerous)

• Composition of sweat:

  • Mostly water

  • Contains salts, metabolic waste, nitrates

  • Slightly acidic, inhibits bacterial growth

apocrine gland

• scent glands, and their secretions usually have an odor

• Axillary (armpit) and anogenital (genitals & anus) regions

• Empty into hair follicles

• Influenced by androgens (hormones that bring on puberty)

• “Smelly”—sweat has different composition than eccrine glands; bacteria break sweat down and cause odor

epidermis

superficial layer; epithelial tissue

contains the following cells:

• keratinocytes

• melanocytes

• dendritic cells (Langerhan’s cells)

• Merkel cells (tactile epithelial cells)

keratinocytes

• Most abundant of all epidermal cells

• Produce keratin for durability and protection

melanocytes

• Produce melanin, a pigment that protects DNA from UV radiation

• Found mostly in Stratum Basale

dendritic cells

• AKA Langerhan’s cells

• Arise from bone marrow, migrate to epidermis

• Ingest foreign material and activate our immune system

Merkel cells

• AKA tactile epithelial cells

• Present at epidermal-dermal junction

• Touch receptor

dermis

deep layer; connective tissue

contains the following:

• papillary layer — areolar CT

• reticular layer — dense irregular CT

papillary layer

areolar CT

• Dermal papillae

  • Capillary loops: tiny blood vessels; nourish 

  • Free nerve endings (pain)

  • Meissner’s corpuscles (touch)

• Dermal ridges in soles and palms cause overlying epidermal ridges (together known as “friction ridges” or “fingerprints”…allow us to grip)

reticular layer

dense irregular CT

• Collagen fibers—most run parallel to skin surface

• Cleavage lines—separations between bundles of collagen…incisions made parallel to these lines allows more rapid healing

skin functions

• Protection

• Body temperature regulation

  • dermal blood vessels constrict and dilate 

• Cutaneous sensation- nerve endings

• Metabolism

  • produce vit D from exposure to UV light

• Excretion — water and wastes through sweat glands

jaundice

accumulation of bilirubin in skin; yellow skin & sclera of the eye

cyanosis

bluish tinge from poorly oxygenated hemoglobin

hemoglobin

causes pink coloration to skin in light colored individuals (skin allows the _______ in the blood to show through)

Endochondral Ossification

1. (9 weeks) — bone collar forms around diaphysis of the hyaline cartilage model

2. (10-11 weeks) — cartilage calcifies in the center of the diaphysis and then develops cavities

3. (3 months) —periosteal bud invades the internal cavities and spongy bone forms

4. (Birth) — diaphysis elongates and a medullary cavity forms, secondary ossification centers appear in the epiphyses

5. (Childhood to adolescence) — epiphyses ossify; when ossification is complete, hyaline cartilage remains only in epiphyseal plates and articular cartilages

EO Step 1

• 9 weeks — bone collar forms around diaphysis of the hyaline cartilage model

  • Mesenchymal cells 🡪 osteoblasts; a collar of bone forms around diaphysis—similar to scaffolding set up around a building under construction (it offers support)

  • Chondrocytes in the middle of diaphysis enlarge at the primary ossification center

EO Step 2

• 10-11 weeks — cartilage calcifies in the center of the diaphysis and then develops cavities

  • Enlarged chondrocytes at primary ossification center calcify the surrounding matrix—this starves them of nutrients and they die

  • As a result, calcified matrix begins to cavitate

  • All the while the healthy cartilage continues to elongate, so the fetus’s skeleton is enlarging

EO Step 3

• 3 months —periosteal bud invades the internal cavities and spongy bone forms

  • In the periosteum, there is a nutrient foramen, a hole through which a periosteal bud invades the internal cavity.

  • The periosteal bud contains blood vessels, nerves, osteogenic cells and osteoclasts

  • Osteoclasts erode the cartilage matrix while osteoblasts lay done bony matrix and spongy bone begins to form

EO Step 4

• Birth —diaphysis elongates and a medullary cavity forms, secondary ossification centers appear in the epiphyses

  • As the primary ossification center grows, the osteoclasts resorb the spongy bone to form the medullary cavity

  • The hyaline cartilage model continues to lengthen, being “chased” by osteoblasts and osteoclasts converting it to bone

  • At the epiphyses, secondary ossification centers appear

EO Step 5

• Childhood to adolescence — epiphyses ossify; when ossification is complete, hyaline cartilage remains only in epiphyseal plates and articular cartilages

• Secondary ossification occurs much the same way as primary ossification except that the spongy bone is not destroyed and replaced with a medullary cavity;  the spongy bone remains

• Completion of secondary ossification means that articular cartilage is now only found at the epiphyseal plates and articular cartilages

8 weeks

before # ________, embryo’s skeleton is made of hyaline cartilage and membranes; bone tissue will eventually replace most of these existing structures

ossification

 occurs differently in cartilage than in membrane

Intramembranous

• The process by which bone develops from a fibrous membrane

• Occurs in cranial bones of the skull and the clavicles

endochondral

Reason: Elongation -> Structure/support

• The process by which a bone develops by replacing hyaline cartilage

• Occurs in all bones below skull (besides clavicles)

compact bone

• external layer; solid

• osteon = functional unit of compact bone

spongy bone

• internal layer

• honeycomb appearance

• contains red bone marrow

• Trabeculae – small, needle-like structures that make up this type of bone

axial skeleton

skull, vertebral column, rib cage

appendicular skeleton

upper and lower limbs, hip and shoulder girdles (i.e. scapula, clavicle)

long bones

Length > width (EX: leg bones, arm bones)

short bones

Cube shaped (EX: carpals & tarsals)

flat bones

Thin, flattened, usually curved (EX: costals, sternum, some skull bones)

irregular bones

Complex shape, don’t fit into any other category (EX: sphenoid, spine)

gross anatomy of long bone

contain the following:

• articular cartilage

• epiphysis (proximal & distal)

• diaphysis

• epiphyseal line

• medullary cavity

• periosteum

• endosteum

articular cartilage

hyaline cartilage; covers ends of long bone; forms joint between two articulating bones

diaphysis

central part / shaft of the bone; skinny part of the bone

epiphysis

Located at the tip of the long bone, typically responsible for articulation; primary source of red marrow in long bones

• proximal — closest to the center of the body

• distal — farther away from the center of the body

epiphyseal line

a ridge on a mature bone that indicates the point where the epiphysis and diaphysis fused together

medullary cavity

hollow and the yellow marrow bone marrow is inside

• yellow marrow — fat used as a last resort by the body

periosteum

double layered membrane that surrounds the entire bone except where the articular cartilage is found

• Inner osteogenic layer: contains osteogenic cells, osteoblasts and osteoclasts

• Outer fibrous layer: made of dense irregular CT

endosteum

lines the internal bone surfaces

gross anatomy of flat bones

• Outer layers of compact bone

• Middle layer of spongy bone

• Inner surfaces covered by endosteum

• Outer surfaces covered by periosteum

  • Except where they form joints with other bones, when they are covered by articular cartilage

osteoporosis

• Underlying problem — osteoclast activity > osteoblast activity (so bone resorption > bone deposition)

  • Result: light porous bones & risk for fractures

• Main population at risk — postmenopausal women

  • estrogen levels plummet, and estrogen is bone protective

• Risk factors — Caucasian ethnicity; thin stature; smoking; poorly controlled diabetes and thyroid disease; sedentary lifestyle; prolonged use of corticosteroids

• Treatment — bisphosphonates (inhibit osteoclast activity); adequate levels of protein, Vitamin D and Calcium in the diet; weight bearing exercise

Osteogenic cells

stem cells found in periosteum and endosteum…give rise to osteoblasts

osteoblasts

Young cells that secrete matrix

osteocyte

osteoblasts become completely surrounded by and turn into ________; maintain matrix

osteoclasts

large cells that resorb (break down) bone by secreting acids and enzymes that release calcium and amino acids into the bloodstream

hyaline cartilage

• most abundant in the body

  • Tip of nose

  • Respiratory tract

  • Costal cartilages

  • Articular cartilage is where bones form joints - ends of the long bones

elastic cartilage

•  very stretchy; expand & recoil

  • Pinnae of ear

  • Epiglottis

fibrocartilage

• meant for absorbing shock; found in areas where we have weight resting on it

  • Intervertebral discs

  • Pubic symphysis

  • Meniscus of knee

structural classifications

3 types based on joint cavity or material — more clear and used more often

• fibrous — bones joined by dense fibrous CT; no joint cavity; most are immovable

• cartilaginous — bones united by cartilage; no joint cavity; not highly movable

• synovial — Bones separated by fluid-filled joint cavity; Categories are based on shape of articular surface, as well as movement joint is capable of

fibrous

bones joined by dense fibrous CT; no joint cavity; most are immovable

• sutures — joint held together with very short, interconnecting fibers, and bone edges interlock (EX: only in the skull)

• syndesmoses — joint held together by a ligament; fibrous tissue can vary in length, but is longer than in sutures

• gomphoses — “peg in socket” joint

cartilaginous

bones united by cartilage; no joint cavity; not highly movable

• synchondroses — bones united by hyaline cartilage

• symphyses — bones united by fibrocartilage

synovial

Bones separated by fluid-filled joint cavity; Categories are based on shape of articular surface, as well as movement joint is capable of

• Plane — articulation between 2 flat bones of similar size

• Hinge — Allows for bending and straightening movements

• Pivot — allow limited rotating movements

• Condylar — articulation between the shallow depression of one bone and the rounded structure of one or more other bones

• Saddle — allows for a wide range of movement, including up and down and back and forth

• Ball-and-socket — rounded or spherical end of one bone fits into a cup-like depression of another bone

functional classifications

3 types based on movement joint allows

• synarthroses — immovable joints

• amphiarthroses — slightly movable joints

• diarthroses — freely movable joints

sutures

 joint held together with very short, interconnecting fibers, and bone edges interlock (EX: only in the skull)

1. allow for growth during youth

2. as we age, ______ ossify & fuse

3. syntoses — closed, immovable sutures

(fibrous joint)

syndesmoses

joint held together by a ligament; fibrous tissue can vary in length, but is longer than in sutures

• Fiber length varies, so movement varies

• Short fibers offer little to no movement 

  • EX: inferior tibiofibular joint

• Longer fibers offer a larger amount of movement

  • EX: interosseous membrane connecting radius and ulna

(fibrous joint)

gomphoses

“peg in socket” joint

• Only examples are the teeth in alveolar sockets

• Fibrous connection is the periodontal ligament

  • Holds tooth in socket

(fibrous joint)

synchondroses

bones united by hyaline cartilage

• Almost all are synarthrotic (immovable)

• EX: Temporary epiphyseal plate joints; Cartilage of 1st rib with manubrium of sternum

(cartilaginous joint)

symphyses

bones united by fibrocartilage

• Fibrocartilage unites bone in symphysis joint

  • Hyaline cartilage also present as articular cartilage on bony surfaces

• strong, amphiarthrotic (slightly movable) joints

• EX: Intervertebral joints; Pubic symphysis

(cartilaginous joint)

plane

articulation between 2 flat bones of similar size

• nonaxial movement ~ don’t operate around any axis; sliding one bone over another (gliding)

• EX: intercarpal joints, intertarsal joints, joints between vertebral articular surfaces

(synovial joint)

Hinge

Allows for bending and straightening movements

• uniaxial, permitting movement along only one axis

• EX: elbow joints, interphalangeal joints

(synovial joint)

pivot

allow limited rotating movements

• uniaxial, allowing rotation around a single axis as the bone moves within the ring

• EX: proximal radioulnar joints, atlantoaxial joint

(synovial joint)

condylar

articulation between the shallow depression of one bone and the rounded structure of one or more other bones

• biaxial, permitting movement in 2 axes

  • 4 movements are possible: flexion, extension, abduction, and adduction

• EX: metacarpophalangeal (knuckle) joints, wrist joints

(synovial joint)

saddle

allows for a wide range of movement, including up and down and back and forth

• biaxial, permitting movement in 2 axes (flexion/extension & abduction/adduction)

• EX: opposable thumb

(synovial joint)

ball in socket

rounded or spherical end of one bone fits into a cup-like depression of another bone

• multiaxial, as possible movements include flexion, extension, abduction, adduction, and rotation

• EX: only joints are the hip and shoulder (glenohumeral) joints

(synovial joint)

gliding

One flat bone surface glides or slips over another surface 

• EX: Intercarpal joints; Intertarsal joints; Between articular processes of vertebrae

angular

Increase or decrease angle between two bones

• Movement along sagittal plane

  • Flexion: decreases the angle of the joint

  • Extension: increases the angle of the joint

  • Hyperextension: movement beyond the anatomical position

• Movement along a frontal plane

  • Abduction: away from the midline

  • Adduction: toward the midline

• Movement in more than one plane

  • Circumduction: Involves flexion, abduction, extension, and adduction of limb; Limb describes cone in space

rotation

turning of bone around its own long axis, toward midline or away from it

• Medial: rotation toward midline

• Lateral: rotation away from midline

• Examples

  1. Rotation between C₁ and C₂ vertebrae

  2. Rotation of humerus and femur

special movements

• Supination and pronation: rotation of radius and ulna

• Dorsiflexion and plantar flexion of foot

• Inversion and eversion of foot

• Protraction and retraction: movement in lateral plane

• Elevation and depression of mandible

• Opposition: movement of thumb

Supination

palms face anteriorly - Radius and ulna parallel

Pronation

palms face posteriorly - Radius rotates over ulna

Dorsiflexion

bending foot toward shin

Plantar flexion

pointing toes

Inversion

sole of foot faces medially

Eversion

sole of foot faces laterally

Protraction

mandible juts out

Retraction

mandible is pulled toward neck

Elevation

lifting body part superiorly- shrugging shoulders

Depression

lowering body part - opening jaw

Opposition

movement of thumb