BIO 209 exam 2 anatomy and physiology

6 functions of skeletal system

support, protection, assistance in movement, mineral homeostasis, blood cell production, triglyceride storage

red marrow

produces RBCs, WBCs, platelets ; present in fetal bones and some bones of the adult

yellow marrow consists mainly of what

adipose cells

hematopoiesis

process of red marrow producing RBCs, WBCs, platelets

structure of long bones

diaphysis (long, main portion), epiphysis (proximal and distal ends), and metaphysis (region between epiphysis and diaphysis), articular cartilage (covering epiphysis; where bone forms joints), periosteum (surrounds bone wherever there isn’t articular cartilage; CT and blood supply), medullary cavity (marrow cavity space in diaphysis), endosteum (lining of medullary cavity)

diaphysis

long, main portion of bone

epiphysis

proximal and distal ends of bone

metaphysis

region between epiphysis and diaphysis; where the epiphyseal line (growth plate) is found

articular cartilage

thin layer of cartilage covering epiphysis where bone forms joints

periosteum

CT and blood supply, surrounds bone wherever not covered by articular cartilage, made of outer fibrous layer (CT) and inner osteogenic layer (cells), assists in fracture repair, helps nourish bone tissue, serves as attachment for ligaments and tendons, attached to underlying bone by perforating (Sharpey’s) fibers

medullary cavity

marrow cavity, space in diaphysis, contains yellow marrow and blood vessels

endosteum

thin membrane lining medullary cavity, contains bone-forming cells and some CT

calcification

the crystallization of mineral salts in the spaces between collagen fibers; initiated by osteoblasts

hardness of bone is gained by ???

crystallized mineral salts

flexibility of bone is caused by ???

collagen fibers

types of cells in bone tissue

osteogenic (bone stem cells), osteoblasts (bone-building cells), osteocytes (mature cells), osteoclasts (break down bone tissue)

what are the only type of bone cells to undergo cell division and what do the daughter cells become?

osteogenic cells - daughter cells become osteoblasts

osteogenic cells

bone stem cells, only bone cells to undergo cell division

osteoblasts

bone-building cells, make and secrete collagen fibers and other components to make the ECM, initiate calcification, osteoblasts surrounds themselves with ECM and become trapped - now they are osteocytes

how are osteocytes formed

osteoblasts surround themselves w ECM and become trapped

osteocytes

mature bone cells, maintain daily metabolism

osteoclasts

huge cells derived from fusion of up to 50 monocytes, concentrated in endosteum, release lysosomal enzymes and acids that digest ECM - called resorption

resorption

when osteoclasts release lysosomal enzymes and acids that digest ECM

compact bone

has few spaces, strongest from of bone tissue, makes up bulk of diaphysis of long bones, made up of osteons, osteons aligned in same direction and run parallel to length of diaphysis, thickest where stresses applied

osteons

repeating structural units; consists of lamellae in concentric circles around a central canal containing blood vessels, nerves, and lymphatics

lacunae

osteocyte-containing spaces between lamellae

canaliculi

radiate in all directions, channels filled w extracellular fluid, projections of osteocyte push into them, connect osteocytes w one another

spongy bone

do NOT have osteons or central canals, consist of trabeculae, makes up most of interior of irregular shaped bones, always covered w layer of compact bone for protection, organized along lines of stress, lightweight

trabeculae

lamellae in irregular pattern of thin columns

spaces between trabeculae are filled with what

red marrow

periosteal arteries

small arteries accompanied by nerves, enter diaphysis through perforating canals, supply periosteum and outer part of compact bone

how do blood vessels pass into bone

through periosteum

nutrient artery

large, near center of diaphysis, passes through hole in compact bone called nutrient foramen, splits into proximal/distal branches upon entering medullary cavity, some bones have more than one (i.e. femur)

metaphyseal arteries

enter the metaphysis, together w nutrient artery supply red marrow and tissue of metaphysis

epiphyseal arteries

enter epiphysis and supply red marrow and tissue of epiphysis

nutrient veins

1-2 accompany nutrient artery, exit through diaphysis

epiphyseal veins and metaphyseal veins

accompany their respective arteries and exit through the metaphysis or epiphysis

periosteal veins

accompany periosteal artery, exits periosteum

what part of bone is rich in sensory nerves

periosteum

ossification / osteogenesis

process by which bone forms

4 stages of ossification / osteogenesis

initial formation in embryo and fetus, growth of bones during childhood, remodeling of bone, repair of fractures

intramembranous ossification

bone forms within mesenchyme (undifferentiated cells that develops into CT, blood, bone, cartilage); simpler of the two methods, flat bones of skull/facial bones/mandible/clavicle formed this way

endochondral ossification

replacement of a cartilage model by bone; most bones formed this way

ossification center

during intramembranous ossification, mesenchyma cells cluster and differentiate into osteogenic cells then osteoblasts

4 steps of intramembranous ossification

ossification center, calcification, formation of trabeculae, development of periosteum

6 steps of endochondral ossification

development of cartilage model, growth of cartilage model, development of primary ossification center, development of medullary cavity, development of secondary ossification centers, formation of articular cartilage and growth plate

during development of cartilage model, mesenchymal cells crowd together in the general shape of bone and develop into ___

chondroblasts

a covering called the ___ covers the cartilage model in endochondral ossification

perichondrium

once chondroblasts become buried in the cartilage ECM they are called ___

chondrocytes

appositional growth

growth in bone thickness

4 steps of appositional growth

ridges in periosteum create groove for periosteal blood vessel, ridges fold + fuse together to form an endosteum-lined tunnel enclosing the blood vessel, osteoblasts in endosteum build new concentric lamellae inward towards center of tunnel - forming a new osteon, bone grows outward as osteoblasts in periosteum build new circumferential lamellae and osteon formation repeats as new periosteal ridges fold over blood vessels

bone remodeling

the replacement of old/injured bone with new bone

bone resorption

osteoclasts REMOVE minerals and collagen fibers

bone deposition

osteoblasts ADD minerals and collagen fibers

does bone remodeling happen the same everywhere?

no; i.e. distal portion of femur replaced every 4 months, bone in diaphysis of femur may not be replaced in entire lifetime

bone fracture

any break in a bone

3 main types of fracture

closed (simple): skin not affected

open (compound): skin pierced by bone

greenstick: cracks in bone

what kind of fracture is common with repetitive forces

stress fractures

4 stages of fracture repair

formation of fracture hematoma (blood mass), fibrocartilaginous callus forms, bony callus formation, bone remodeling

hypercalcemia vs hypercalciuria

too much calcium in blood vs in urine

hypocalcemia

too little calcium in blood

what hormone regulates calcium levels

parathyroid hormone (PTH)

effects of PTH

increases activity of osteoclasts (Ca releases into blood), acts on kidneys (reduces Ca loss through urine), stimulates formation of calcitrol (increases absorption of Ca from food)

when Ca rises in blood, parafollicular cells in thyroid secrete ___

calcitonin (CT) - inhibits osteoclasts, speeds Ca uptake by bone, accelerates Ca deposition

main mechanical stresses are those that come from ___ and ___

muscle and gravity

two principal effects of aging

loss of bone mass, brittleness

rickets

softening of bones caused by deficiency of vitamin D, calcium, or phosphate. if blood Ca too low, body will take it from the bones. vitamin D is necessary for absorption of dietary Ca

symptoms of rickets

pain, dental deformities, incr bone fractures, bossing (bulging frontal bone), bowlegs, pectus carinatum (pigeon chest; breastbone pushes out), spine deformities

osteoporosis

“porous bones”, decr bone density, primary type 1 (postmenopausal), primary type 2 (senile), secondary (caused by meds or secondary to other disease)

gigantism

excessive growth hormone production BEFORE growth plates close, usually caused by benign tumor of the pituitary, muscles and bones and organs grow

acromegaly

excessive growth hormone AFTER growth plates close, body tissues gradually enlarge, bones grow in thickness (NOT length), usually caused by tumor on pituitary, results in severe disfigurement

dwarfism

can be caused by 200 medical conditions, can be proportionate or disproportionate, achondroplasia accounts for 70% of cases

marfan syndrome

disorder of CT, mutations in fibrillin-1 gene, too much growth in long bones. treatment usually only addresses individual physical abnormalities, i.e. slowing heart rate

physical characteristics: very tall w/ very long limbs, chest caves in or sticks out, lens moves, scoliosis, learning disabilities, too flexible joints, AORTA STRETCHES

fibrodysplasia ossificans progressiva - stone man syndrome

CT and muscle tissue becomes ossified when damaged, often born with malformed big toes, extremely rare, caused by mutations in ACVR1 gene (controls growth/development of bones/muscles), kids with this will develop bone growths starting @ neck moving to the shoulders + chest + lower body. Harry Eastlack most well known with this disease

proteus syndrome - elephant man disease

children born without obvious deformities, tumors + bone growths appear with age - skull, limbs, and soles of feet will be affected. AKT1 gene strongly associated w this disease - critical for growth promoting signals.

characteristics of skeletal muscle

most attached to bones (except diaphragm, tongue, lips, eyes), striated, voluntary

characteristics of cardiac muscle

forms heart, striated, involuntary

autorhythmicity

built-in rhythm / pacemaker of heart and some smooth muscle; speed controlled by hormones and neurotransmitters

characteristics of smooth muscle

walls of hollow internal structures (blood vessels, airways, most organs in abdominal cavity), skin, lacks striations, involuntary, some have autorhythmicity

4 functions of muscular tissue

producing body movements, stabilizing body positions, generating heat (thermogenesis), storing/moving substances within body

thermogenesis

as muscles contract, they generate heat

4 properties of muscular tissues

electrical excitability, contractility (contract forcefully when stimulated), extensibility (ability to stretch within limits without being damaged), elasticity

connective tissue

surrounds and protects muscle tissue, subcutaneous layer (hypodermis) separates muscle from skin, areolar (loose) CT and adipose tissue, provides pathways for nerves/blood vessels/lymphatic vells to enter/exit muscle, adipose tissue acts as insulating and protective layer

fascia

dense sheet or broad band of dense irregular CT lining body walls/limbs, supports and surrounds muscles + other organs, holds muscles w/ similar function together, carries nerves/blood vessels/lymphatic vessels, fills space between muscles

3 layers of CT that extend from fascia to protect and strengthen skeletal muscle

epimysium (outermost), perimysium (separates fibers into fascicles), endomysium (penetrates interior of each fascicle and separates individual muscle fibers)

epimysium

outermost layer, encircles muscle

perimysium

surrounds groups of 10-100+ fibers and separates them into fascicles, some of which can be seen w/ naked eye. gives meat the grain!

endomysium

penetrates interior of each fascicle and separates individual muscle fibers from one another

epimysium, perimysium, and endomysium are ___ with tendons or aponeuroses

continuous

how many arteries and how many veins accompany each nerve in skeletal muscle

one artery, one or two veins

somatic motor neurons

stimulate contraction, threadlike axon that extends from brain or spinal cord to group of fibers

propioceptors

sensory; information about force generated at tendons

nociceptors

pain receptors

capillaries

plentiful in muscle tissue, in close contact w muscle fibers, bring in O2 and nutrients, remove waste and heat

skeletal muscle fibers arise from fusion of hundreds to thousands of ___

myoblasts

does cell division occur after cells fuse to form skeletal muscle fibers?

no; and the number of fibers is set before birth

___, found at periphery of muscle fiber, help muscles grow (hypertrophy) and also help with healing after injury

satellite cells

what is the plasma membrane called in muscle fibers

sarcolemma/myolemma

transverse (T) tubules

tunnel from surface toward the center of each muscle fiber, ENSURE ACTION POTENTIAL REACHES ALL PARTS OF THE MUSCLE

what is cytoplasm called in muscles

sarcoplasm