A&P Exam 2

-Calcium Homeostasis- Controlled condition: Blood Ca Stimulus: decreases blood Ca Receptors: PTH gland cells Control Center: gene for PTH within nucleus of PTH gland cell Effectors: Osteoclasts -stimulus causes Ca to decrease -PTH cells detect change and increase production of cyclic AMP -gene for PTH within nucleus of PTH cell detects increase in cyclic AMP (INPUT) -PTH synthesis speeds up, more PTH is released into blood (output) -presence of increased PTH increases number and activity of osteoclasts, which step up rate of RESORPTION (breakdown- to release into bloodstream) -resulting release of Ca from bone into blood returns blood Ca levels to normal

-when blood Ca is low, Ca is released form bone into blood to return to homeostasis **when blood Ca low, bone resorption occurs (breakdown to release into blood stream**

Primary Curve: Thoracic and sacral curves Secondary Curve: Cervical and lumbar curves

Atlas (C1) -NO vertebral body or spinous processes -BIGGER vertebral foramen -articulates with occipital bone/condyle -permits head nodding 'yes' (why there is no v body or spinous process) Axis (C2) -vertebral body -DENS (permits side to side movement (no) -NO other bone has a dens -articulates with C1

Endochondral Ossification occurs in epiphyseal plates of long bones as they grow length wise (4 zones) 4 zones of epiphyseal growth plate 1) zone of resting cartilage 2) zone of proliferating cartilage 3) zone of hypertrophic cartilage 4) zone of calcified cartilage

4 Zones of Epiphyseal Growth Plate 1) Resting Cartilage: -small chondrocytes; do not function in gone growth! -anchor epi plate to epiphysis of bone 2) Proliferating Cartilage: -large chondrocytes stacked like coins -go thru interstitial growth (length) as they divide and secrete ECM -they divide to replace those that die at diaphysis side at epi plate 3) Hypertrophic Cartilage: -large mature chondros in columns 4) Calcified Cartilage: -made of DEAD chondrocytes bc ECM has calcified around them -osteoCLASTS dissolve cartilage -osteoBLASTS replace calcified cartilage by endochondral ossification (replacement of cartilage with bone) (osteoCLASTS: carvers, breakdown, resorption) (osteoBLASTS: builders, bone formation, deposition)

Thin Skin -no epidermal ridges (fewer dermal papillae) -hair follicles -arrector pili muscles -sebaceous glands -few sudoriferous (sweat) glands -sparse sensory receptors Thick Skin -epidermal ridges d/t more dermal papillae in rows -NO hair follicles -NO sebaceous (oil) glands -more sudoriferous (sweat) glands -denser sensory receptors

Axial Skeleton (80 bones) -skull, auditory ossicles, hyoid bone, ribs, sternum, vertebrae, sacrum Appendicular (126 bones) -both girdles (connect limbs to axial) -upper and lower limbs

Fracture Repair Phases (3) Reactive (early inflammatory) -hematoma due to fractured vessels of osteon's haversian canals -circulation stops at hematoma site, so nearby bone cells die -swelling/inflammation d/t dead bone cells -dead stuff removed by osteoclasts/phagocytes -swollen/painful/red/hot Reparative (A and B) **formation of soft (fibrocartilaginous) callus, then bony callus (spongy bone) to bridge gap between broken ends of bones A: 3 weeks -formation of new immature bone (fibrocartilage) -soft callus (fibrocartilaginous), formation of new vessels B: 3-4 months -fibrocartilaginous (soft) callus converted to spongy bone and is then called bony callus Bone Remodeling -dead portion gradually reabsorbed (broken down) by osteoCLASTS -compact replaces spongy around periphery of fracture -thickened area on surface of bone

Bone Fractures

Bone Cells (4) Osteoprogenitor -STEM CELLS (undergo division) -come from mesenchyme -turn into osteoBLASTS -inner periosteum, endosteum, haversian canals Osteoblasts (builders, deposition) -come from osteoprogenitor cells -secrete ECM and become osteoCYTES -secrete collagen, start calcification -increase deposition (build ECM, secrete Ca and phos) Osteocytes -made from osteoBLASTS -mature bone cell -daily metabolism (exchange of nutrients/wastes within blood) Osteoclasts (bone carver/breaker, resorption) -come from monocytes (WBCs) -concentrated in endosteum -remodel bones causing Ca release (increases resorption back into blood) -regulate Ca -ruffled border secretes enzyme that breaks down bone (bone resorption) -break down to perform maintenance/repair

Bone Fractures Open (compound) -end(s) break thru skin -skin penetrated (opposite of closed/simp) Comminuted -splintered/crushed -fix: align, set together Greenstick (partial) -twisty, partial tearing -ONLY IN KIDS bc bones not fully ossified Impacted -one end forcefully driven into other end

True Ribs (1-7) -cartilage directly connected to sternum -vertebrosternal False Ribs (9-12) -cartilage not directly connected to sternum (8-10) -vertebrochondral Floating Ribs (11-12) -NO COSTAL CARTILAGE -do not connect to sternum -vertebral **only T1-T10 articulate with tubercules of rib on transverse process

Clavicle -medial (sternal end) articulates with manubrium of sternum -Lateral (acromial) end articulates with acromion of scapula Scapula -acromion, coracoid process (crow's beak), glenoid cavity -scapula attaches to humerus at glenoid cavity

Compact Bone vs Spongy Bone Compact= Osteons Spongy= Trabeculae

Compact: -providing protection/support -made of repeating structural units (osteons) Spongy: -NO OSTEONS -lightweight; tissue support -interior of compact bone -irregular pattern of lamellae called trabeculae ---- concentric lamellae ---- osteocytes in lacunae ---- canaliculi ----trabeculae supports RBM ----spaces filled with red AND yellow bone marrow

Calcium Blood Levels -role of bone in Ca homeostasis is to help buffer the blood Ca level -when level decreases, osteoclasts release Ca (by breaking it down into bloodstream **resorption occurs** -when level increases, osteoblasts absorb Ca (by forming bone) **deposition occurs**

Deposition: bone formation (osteoBlasts- bone builders) Resorption: bone breakdown (osteoClasts- carvers, breakers)

5 bone shapes Long (humerus, femur, fingers) -length>width -RBM at tip -epiphyseal plate (gives rise to new bone) -**endochondral growth** Short (trapezoid, wrist/ankle bones) -cube shaped Flat (sternum, skull, scapula) -thin layers of plates -no medullary cavity -**inrtramembranous ossification** Irregular (vertebra, pelvis) -complex shapes Sesamoid (patella) -shaped like sesame seed

Depressions: allowing formation of joints -fossa Openings: passage of soft tissue (blood vessels, nerves, ligaments, tendons) -sulcus -foramen -fissure Processes: form joints/attachment points for connective tissue -projections or outgrowths Processes form joints: -condyle -facet -head Processes form attachment points: -crest (mountain) -epicondyle -Line (hill) -spinous process -trochanter (ONLY FEMUR) -tubercle -tuberosity (rough and bumpy)

Skin Functions 1) Thermoregulation -sweating -adjusting flow of blood in dermis 2) blood reservoir -dermis: blood vessels carrying 10% of blood flow 3) protection -Keratin: resist microbe entry, lamellar granules prevent water loss/ dehydration, prevent water entry during shower/swim -sebum: keeps skin from drying, has bactericidal chemicals -acidic sweat: retards growth of microbes -melanin: shield against UV damage -intraepidermal macrophages: alert immune system -dermal macrophages: kill bacteria/viruses 4) cutaneous sensations -touch/pressure/vibration/tickle/temp 5) excretion and absorption -salts, CO2, ammonia and urea (protein breakdown) via sweat -lipid soluble materials penetrate skin (vitamins A, D, E, K) 6) synthesis of vitamin D -UV rays activate molecule, enzymes in liver/kidney modify activated molecule and produce calcitrol (most active form of vitamin D) -only small amount of UV exposure required for vitamin D synthesis -Calcitrol: -aids absorption of Ca from foods in GI tract to blood -Vitamin D: 7) Immune -enhance phagocytic activity -increase prod of antimicrobial substances in phagocytes -regulate immune -reduce inflammation

Effects of Aging Wrinkles: -collagen fibers decrease, stiffen, disorganize into shapeless tangle -elastic fibers lose elasticity, thicken into clumps -fibroblasts (produce collagen and elastic) decrease -result> wrinkles Dehydration/cracking: -decreased size of sebaceous glands -broken skin more susceptible to infxn Sweat production decreases: -increased heat stroke Decreased melanocytes: -gray hair -atypical skin pigmentation -hair follicles stop producing hairs -increase in SIZE of melanocytes > pigment blotch (age spots) SubQ fat lost, decreased skin thickness: -walls of blood vessels become thicker -migration of cells from stratum basale to surface slows a lot Nails become more brittle: -dehydration -repeated use of cuticle remover and nail polish Decreased immunity: -skin heals poorly -cracked skin -decreased intraepidermal macrophages -less efficient phagocytes

Cells in Epidermis (4) 1) Keratinocytes: -MAKE KERATIN -lamellar granules: sealant prohibiting water loss/bacteria entry from skin -most abundant -start dying in granulosum- all layers) 2) Melanocytes: -MAKE and SECRETE melanin (skin pigmentation, protection from UV light) -melanocytes secrete melanin onto nucleus of surrounding keratinocytes (veil of melanin around nucleus to protect DNA) -stratum basale **melanocytes MAKE melanin **keratinocytes CONTAIN melanin 3) Intraepidermal Macrophages (Langerhans) -Warriors!!! -participate in immune response -derived from bone marrow, migrate to EPIdermis -stratum spinosum 4)Tactile Epithelial Cells (Merkel) -connect to BASE of nerve via tactile (merkel) disc -SENSORY TOUCH (i.e. light brush on face) -in stratum basale (deepest layer of epidermis)

Germinal Layers (3) Ectoderm: epidermis -gives rise to nervous system and epidermis -SKIN COMES FROM ECTODERM -outer most layer of neural tube Mesoderm: dermis -all connective tissues come from mesoderm -muscles, CT (bone, blood), vasculature -DERMIS develops form mesoderm Endoderm: -endo=inside -all squishy organs (guts/organs etc) anything that's inside

Parts of Hair 1) Shaft: (above skin surface) -Medulla (may not be present in thin hair) -Cortex -Cuticle (outermost) 2) Follicle (below skin) -external/internal root sheath (or 'epithelial root sheath') -surrounding each follicle are dendrites of neurons that form hair root plexus 3) Root (penetrates into dermis) -epithelial sheath (external/internal) -dermal root sheath (surrounds epithelial) -medulla -cortex -cuticle -hair root plexus (surrounded by free nerve ending of neuron and blood vessels) (so when you wax, you pull the hair root plexus, leaving the nerve root exposed) Hair Bulb: -hair matrix -papilla-areolar CT and blood vessels Hair Matrix: responsible for growth of hair and internal root sheath (part of hair bulb)

Growth Stages of Hair Growth Stage: -cells of matrix divide (2-6 years) Regression: -matrix cells STOP dividing (2-3weeks) Resting: -old hair foot falls/pushes out -new hair begins to grow (3 months)

Intramembranous Ossification: bone forms directly within mesenchyme ***from mesenchyme*** -flat bones Endochondral Ossification: bone forms within hyaline cartilage that develops from mesenchyme ***from cartilage*** -long bones -epiphyseal plate **both replace pre-existing connective tissue with bone; does NOT lead to difference in bone structure **just different methods of bone formation

Intramembranous Ossification (4) 1) development of ossification center -where bone will develop -mesenchyme cells cluster at site (oss center) where cells DIFFERENTIATE into osteoprogenitor (stem cells) and osteoblasts (bone builders -osteoblasts secrete ECM 2) calcification -ECM secretion stops -osteoblasts are now osteocytes and form lacunae/canaliculi -calcium deposited in ECM and it hardens (calcifies) 3) formation of trabeculae -ECM forms, trabeculae fuse to form spongy bone around blood vessels -CT in trabeculae differentiate into RBM 4) development of periosteum -mesenchyme condenses= periosteum -compact bone replaces outer layer **much of bone remodeled (destroyed and reformed) as bone is transformed into adult size

Types of Melanin Pheomelanin: yellow/red (blonde red) Eumelanin: brown/black (darker hair/skin) ***can have combo of two*** White: air bubble in shaft, v little melanin

Lack of Melanin Vitiligo: -chronic, likely genetic/autoimmune -patches of depigmentation Albinism: -congenital -absence of pigment -defect of enzyme involved in melanin production

Elbow: capitulum of humerus and trochlea of ulna

Radial head is PROXIMAL and articulates w/ capitulum of humerus Ulna head is DISTAL and articulates w/ carpals

COMPACT BONE Lacunae: spaces between concentric lamellae contain osteocytes Canaliculi: small channels w/ ECF osteocytes communicate via gap junctions provide nutrients, remove waste Lamellae: thin layer of membrane/tissue plate Interstitial Lamellae: area between osteons Concentric Lamellae: circular plates of mineralized ECM; surrounds blood vessels/nerves in central canal Circumferential Lamellae: surrounds outer/inner bone shaft

SPONGEY BONE Trabeculae: -lamellae arranged in irregular patterns of columns -has concentric lamellae, osteocytes in lacunae, and canaliculi -lightweight, resists stress, supports RBM Spaces filled with: RBM -makes RBCs/WBCs/plts (hemapoiesis) -hips, ribs, sternum, vertebrae, epiphysis (ends) of humerus and femur YBM -adipose tissue -stores triglycerides -adults ***both marrows have lots of blood vessels***

Stem cells of nail -nail matrix

Skin Glands (4) Eccrine **most numerous** -deep dermis/subq -most of body, esp. forehead -duct ends as pore on surface of skin -BEFORE puberty -thermoregulatory/waste Apocrine (sexual-after) -deep dermis/subq -TO HAIR FOLLICLE -AFTER puberty -stress/sexual/emotional sweat -same as eccrine sweat plus lipids/protein (milky) Sebaceous (acne, so after) -dermis -to HAIR FOLLICLE -ABSENT IN THICK SKIN (no palms/soles) -AFTER PUBERTY -sebum (keeps moist, prevents some bacteria) Ceruminous (obvi before puberty) -deep subq -external auditory canal -BEFORE PUBERTY -secretes cerumen -protective barrier against foreign bodies -modified sweat gland (sudoriferous)