Tuesday, July 1, 2008

Compendium Review Unit 3 Major Topic: Movement

Movement

I. Skeletal System
II. Muscular System

I. Skeletal System
A. Overview of Skeletal System
1. Functions of the skeleton
a. supports the body
b. protects soft body parts (skull, rib cage, vertebrae)
c. produces blood cells
d. stores minerals and fat
e. permits flexible body movement - along with muscles
2. Anatomy of a long bone
a. diaphysis with medullary cavity - compact bone, endosteum, yellowish bone marrow
b. epiphysis - articular cartilage, spongy bone containg red bone marrow
c. periosteum - covers long bone, is continuous with ligaments and tendons
d. bone
i. compact - osteon - lacunae - osteocyte. canaliculi connect lacunae, run thru matrix
ii. spongy - trabeculae (plates) separated by unequal spaces, filled with red bone marrow. osteocytes irregular placement in trabeculae
e. cartilage - flexible, chondrocytes in irregularly grouped lacunae, no nerves or vessels
i. hyaline cartilage - firm, somewhat flexible, ends of long bones, nose, ends of ribs, larynx, trachea
ii. fibrocartilage - strong, withstand tension & pressure, disk btwn vertebrae, knee
iii. elastic cartilage - more flexible than hyaline, ear flaps, epiglottis
f. fibrous connective tissue
i. ligaments
ii. tendons
Figure 11.1 from the text shows the anatomy of a long bone.











B. Bone Growth, Remodeling, and Repair osteoblasts, osteocytes, osteoclasts
1. Bone development and growth
a. intramembranous ossification - formation of bone developed between sheets of fibrous connective tissue. eg skull
b. endochondral ossification - bone growth occurs as bone replaces the cartilaginous models of the bones
i. cartilage model - chondrocytes lay down cartilage
ii. bone collar - matrix secreted from osteoblasts calcifies, covers diaphysis
iii. primary ossificaton center - osteoblasts in interior lay down spongy bone
iv. medullary cavity & secondary ossification sites - osteoclasts abosorb spongy bone of diaphysis, creates medullary cavity. secondary site form in epiphysis
v. epiphyseal (growth) plate - band of cartilage between primary & each secondary site.
vi. final size - determined when epiphyseal plates close
c. hormones affect bone growth - growth hormone, thyroid hormone,
2. Bone remodeling and its role in homeostasis
a. keeps bone strong, 18% of bone recycled each year
b. allows body to regulate amount of calcium in blood, if blood calcium is high, it can be deposited into bone, if low, calcium removed from bones
c. parathyroid hormone - accelerates bone recycling - increases blood calcium
d. calcitonin - hormone that acts opposite to PTH
e. allows bones to respond to stress -
f. walking, jogging, weight lifting - stimulates work of osteoblasts
3. Bone repair
a. hematoma
b. fibrocartilaginous callus
c. bony callus
d. remodeling
Figure 11.2 from the text illustrates endochondral ossification of a long bone. Additional images from the text can be found here.C. Bones of the Axial Skeleton
Figure 11.7 from the text shows the bones of the human skull.
1. The skull
a. cranium - protects brain, made of 8 bones in adults, some contain sinuses: frontal, parietal, occipital, temporal, sphenoid, ethmoid
b. facial bones
Figure 11.8 from the text shows the facial bones and the hyoid bone.
2. The hyoid bone
a. only bone that does not articulate with another bone
b. attached to temporal bones by muscles & ligaments, to larynx by membrane
c. anchors tongue, site for attachment of muscles associated w/swallowing
3. The vertebral column 33 vertebrae
Figure 11.9 from the text shows the vertebral column.
a. 4 curvatures provide more resilience & strength for upright position
b. protects spinal cord, site of attachment for muscles that move the vertebral column
c. types: cervical, thoracic, lumbar, sacral, coccyx
d. intervertebral disks - fibrocartilage = padding
4. The rib cage protective and flexible
a. composed of the thoracic vertebrae, the ribs & associated cartilages, & sternum
b. the ribs - 12 pairs, all connect to thoracic vertebrae, upper 7 connect w/sternum
c. the sternum - lies in midline of body, with ribs protect heart, lungs
i. composed of manubruim, body, xipoid process
Figure 11.10 from the text shows details of the thoracic verebrae and the rib cage.D. Bones of the Appendicular Skeleton
1. The pectoral girdle and the upper limb flexibility
Figure 11.11 from the text shows the bones of the pectoral girdle and the upper limb.
a. pectoral girdle: scapula, clavicle
b. upper limb: arm - humerus, forearm - radius, ulna, hand - carpals, metacarpals, phalanges
2. The pelvic girdle and lower limb strength
a. pelvic girdle: coxal bones
b. lower limbs: thigh - femur, leg - tibia, fibula, foot - tarsals, metatarsals, phalanges
Figure 11.12 shows the bones of the pelvic girdle and lower limb.E. Articulations
1. Joints
a. cartilaginous - connected by hyaline cartilage (costal cartilages that join ribs to sternum) or by fibrocartilage (intervertebral disks), tend to be movable
b. fibrous - many are immovable (sutures between cranial bones)
c. synovial - freely movable, contain bursa, menisci, synovial fluid
Figure 11.13 from the text shows synovial joints. Figure 11.14 illustrates synovial joint movements.









Definitions for Chapter 11 can be found here.

II. Muscular System
A. Overview of Muscular System
1. Types of muscles
a. smooth muscle fibers - spindle-shaped, uninucleated, form sheets, in walls of hollow internal organs, cause contraction (involuntary) of walls
b. cardiac muslce - forms heart wall, cells generally uninucleated, striated, tubular, branched (allowing interlocking of fibers at intercalated disks), gap junctions in plasma membrane, contraction rhythmical, involuntary
c. skeletal muscle fibers - tubular, multinucleated, striated, attached to skeleton, long - run length of muscle, voluntary
Figure 12.1 from the text shows the 3 types of muscle tissue.2. Functions of skeletal muscles
a. support the body - contraction opposes force of gravity, allows upright
b. make bones move
c. help maintain a constant body temp - heat from breakdown of ATP
d. contraction assists movement in cardiovascular and lymphatic vessels
e. help protect internal organs and stabilize joints
3. Skeletal muscles of the body
a. basic structure
i. fascicles - bundles of skeletal muscle fibers that make up a muscle
ii. connective tissue surrounds both fiber and fascicle
iii. fascia cover muscle and extend beyond muscle to become tendon
b. skeletal muscles work in pairs
i. prime mover - muscle doing most of the work, synergists - assist prime mover, antagonist - muscle that acts opposite to a prime mover
ii. origin & insertion, insertion - contracting muscle pulls on tendons at insertion
4. Names and actions of skeletal muscles
a. size - eg gluteus maximus
b. shape - eg deltoid, trapezius, latissimus, terres
c. location - eg external obliques, pectoralis, gluteus, brachii, sub
d. direction of muscle fibers - eg rectus abdominis, obicularis, trasverse, oblique
e. attachment - eg sternocleidomastoid, brachioradialis
f. number of attachments - eg biceps brachii, quadriceps femoris
g. action - eg extensor digitorum, adductor longus, flexor, masseter, levator
Figure 12.4 from the text shows the superficial skeletal muscles.B. Skeletal Muscle Fiber Contraction
Figure 12.5 shows skeletal muscle fiber structure and function.
1. Muscle fibers and how they slide
a. myofibrils and sarcomeres
i. muscle fibers->myofibrils->sarcomeres->myofilaments=actin & myosin
ii. actin - protein that makes up thin filaments (I band), attached to Z line
iii. myosin - protein that makes up thick filaments (H zone)
iv. action & myosin overlapping make up A band
b. myofilaments
i. thick filaments - several 100 molecules of myosin
ii. thin filaments - 2 intertwining strands of actin, tropomyosin, troponin
iii. sliding filaments - contraction of muscle fiber starts when calcium released from sarcoplasmic reticululm.
iv. sliding filament model - sarcomeres shorten by by actin filaments sliding past myosin filaments. actin fil. approach each other. myosin pull actin
v. ATP (broken down by myosin) supplies energy for muscle contraction
2. Control of muscle fiber contraction
a. nerve impulse reaches axon terminal, synaptic vesicles relase ACh into synaptic cleft
b. ACh binds to receptors in sarcolemma->generates impulses, spread down T tubules
c. sarcoplasmic reticulum releases Ca2+->leads to sarcomere contraction
d. Ca2+ combines with troponin, causes tropomyosin threads to shift, exposing myosin binding site on actin
e. ADP and P on myosin heads attach to actin filament
f. ADP and P are released and cross-briges bend sharply (power stroke)
g. ATP molecules bind to myosin heads, cross-bridges broken, heads detach from actin
h. ATP is hydrolyzed to ADP and P, process starts over, myosin reattaches further
along actin filament
i. cycle recurs until calcium ions are actively (requires ATP) returned to storage site in sarcoplasmic reticulum
Figure 12.6 from the text illustrates the neuromuscular junction and Figure 12.7 shows the function of calcium and myosin in muscle contraction.









C. Whole Muscle Contraction
1. Muscles have motor units
a. varying ratios of innervation - motor axons per muscle fiber (ie 1 motor neuron per 23 muscle fibers in the ocular muscles vs 1:1000 in the gastrocnemius)
b. muschel twitch - occurs when motor unit stimulation is infrequent
c. latent period, contraction period, relaxation period
d. tetanus achieved from summation of rapid series of stimuli
e. recruitment - when more and more muscle units in a muscle are activated upon increased intensity of nervous stimulation
f. muscle tone - when some motor units are always contracted, but not enough to cause movement
1. Energy for muscle contraction
a. fuel source for exercise
i. glycogen & fat stored in muscle
ii. blood glucose & plasma fatty acids
b. sources of ATP for muscle contraction, formation of ATP by:
i. creatine phosphate (CP) - anaerobic, CP pluls ADP = ATP & creatine
- CP formed only when muslce is resting, limited amt stored
- occurs in midst of sliding filaments
- used at beginning of submaximal exercise & during short-term, high-intensity exercise that lasts less than 5 seconds
ii. fermentation - anaerobic
- hormones provide signal to muscle cells to break down glycogen
- fast-acting, results in buildup of lactate
- oxygen debt required to complete metabolism of lactate
iii. cellular respiration - aerobic
- can use glucose from breakdown of glycogen, glucose taken up from blood, fatty acids
2. Fast-twitch and slow-twitch muscle fibers
Figure 12.11 shows fast- and slow-twitch muscle fibers.
a. fast-twitch fibers - (usually) anaerobic, designed for strength
i. motor units contain many fibers, explosions of energy
ii. light color b/c few mitochondria, little or no myoglobin, fewer blood vesssels
iii. vulnerable to accumulation of lactate = fatigue
b. slow-twitch fibers - (mostly) aerobic, more endurance
i. tire only when fuel supply is gone
ii. dark color b/c many mitochondria, contain myoglobin, dense capillary beds
iii. draw more blood & oxygen than fast-twitch
iv. lowe maximum tension, highly resistant to fatigue
v. steady, prolonged production of ATP when oxygen is available
3. Delayed onset of muscle soreness
a. thought to occur with any activity that causes muscles to contract while they are lengthening
b. prevention - warm up, cool down, start gradually with new activity
Figure 12.9 shows the fuel sources for muscle contraction during submaximal exercise (65-75% of effort) and figure 12.10 shows the 3 ways that muscles product ATP.










D. Muscular Disorders see definitions
1. Common muscular conditions
a. spasms, convulsions, cramps, facial tics, strain, sprain
b. tendinitis and bursitis
2. Muscular diseases
a. myalgia and fibromyalgia
b. muscular dystrophy
c. myasthenia gravis
d. amyotrophic lateral sclerosis
E. Homeostasis
1. Both systems produce movement
a. movement essential to maintaining homeostasis
b. skeletal & muscular systems work together to enable body movement
c. allow us to respond to changes in environment
d. other movements contribute to homeostasis - chewing food, contractions of peristalsis, beating of heart, movement aids in venous return
2. Both systems protecy body parts
3. Bones store and release calcium
4. Blood cells produced in bones
5. Muscles help maintain body temperature

Figure 12.12 shows how systems of the human body work together.

Definitions from Chapter 12 can be found here.

REFERENCES:
Mader, Syliva S. Human Biology. New York, NY: McGraw-Hill (2008).

Links provided throughout the summary take you to online sources.


IMPORTANT NOTE: Any time "text" or "the text" is referenced in the above summary, I am referring to the textbook Human Biology by Sylvia Mader (cited directly above).

2 comments:

Kibar said...

Hi Sarah,
Nice Blog. I would like to use your diagram of the actin-myosin binding proteins during cardiac contraction. I need to ask permission from Mcgraw-Hill, the publishers but would like to know where you got it from. Could you email me please? kyared@partners.org
Thanks,
Kibar

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