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Inquiry into Life
Twelfth Edition
Sylvia S. Mader
Chapter 19
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
19.1 Anatomy and Physiology of Bone
• Structure of Bone and Associated tissues
– Compact bone is highly organized
• Composed of osteons which are the functional units of bone
• Osteocytes (bone cells) lie in lacunae
– Arranged in concentric circles around a central canal
– Central canals contains blood vessels, lymphatic vessels, and
nerves
• Lacunae are interconnected by canaliculi
• Cytoplasmic extensions of osteocytes extend through
canaliculi
– Allows nutrients to flow from central canal to the cells
19.1 Anatomy and Physiology of Bone
• Structure of Bone and Associated tissues
– Spongy bone has an unorganized appearance
• Osteocytes are found in trabeculae
– Numerous thin plates surrounded by unequal spaces
– Plates follow lines of stress so spongy bone is light but
strong
• Spaces filled with red bone marrow
– Red bone marrow produces blood cells
– In infants, red marrow is present in cavities of all bones
– In adults, red bone marrow is present in the spongy bone
of the skull, sternum, ribs, vertebrae, and ends of long
bones
Anatomy of Bone
19.1 Anatomy and Physiology of Bone
• Structure of Bone and Associated tissues
– Cartilage
• Not as strong as bone but more flexible
• Matrix is gel-like with lacunae for chondrocytes
– Three types of Cartilage
• Hyaline- firm, white, contains collagen fibers
– Ends of long bones, nose, ends of ribs, larynx, trachea
• Fibrocartilage-stronger, thick collagen bands, can withstand
both pressure and tension
– Intervertebral disks, knees
• Elastic- most flexible, elastin fibers
– External ears and epiglottis
19.1 Anatomy and Physiology of Bone
• Structure of Bone and Associated tissues
– Dense Fibrous Connective Tissue
• Rows of fibroblasts separated by bundles of collagen fibers
• Ligaments (connect bone to bone)
• Tendons (connect muscle to bone)
19.1 Anatomy and Physiology of Bone
• Organization of Tissues in the Skeleton
– Bones are classified by shape
• Long bones- longer than they are wide
– Covered by periosteum-fibrous connective tissue
– Epiphysis- widened end of a long bone
» composed of spongy bone
» contains red marrow
– Diaphysis-shaft of a long bone
» composed of compact bone
» Encloses the medullary cavity that is filled with yellow
marrow
– Surrounding the spongy bone is thin layer of compact
bone and a layer of hyaline cartilage
19.1 Anatomy and Physiology of Bone
• Bone Growth and Repair
– Remodeling of Bones
• Bone is continuously broken down and built up
• Osteoclasts-break down bone matrix and release calcium to
blood
– Process takes about three weeks
• Osteoblasts-pick up calcium from blood and deposit it in new
bone matrix
– Get trapped in matrix and become osteocytes within lacunae
• Remodeling can change bone thickness
– Affected by hormones and physical use
19.1 Anatomy and Physiology of Bone
• Bone Development and Growth
– Most bones of the human skeleton first appear as
hyaline cartilage
• Skull bones are the exception
– Endochondral Ossification
• Hyaline cartilage “template” forms first
• Cartilage breaks down in center, and periosteum develops
– Osteoblasts migrate in and produce spongy bone in what is
called the primary ossification center
– Other osteoblasts then produce compact bone beneath the
periosteum and spongy bone is broken down
19.1 Anatomy and Physiology of Bone
• Bone Development and Growth
– Endochondral Ossification Continued
• Secondary ossification centers form in ends of the bone
– Spongy bone forms and is not broken down
– Growth plate-band of cartilage between primary and secondary
growth centers
» Allows growth in length to continue
– The rate of growth is controlled by hormones
– Eventually, the growth plates become ossified, and the bones
stop growing
Endochondral Ossification
of a Long Bone
19.2 Bones of the Skeleton
19.2 Bones of the Skeleton
• Functions
– Structural support
• Bones of lower limbs, pelvic girdle
– Protection of soft body parts
• Skull, rib cage
– Production of blood cells
• Fetus: All bones
• Adults: Skull (flat bones), ribs, sternum, clavicles. vertebrae,and
pelvis
– Storage of minerals and fat
• Calcium phosphate in bone matrix
• Fat in yellow marrow
– Flexible body movement
• Along with muscles
19.2 Bones of the Skeleton
• Classification of the Bones
– Axial Skeleton
• Skull, vertebral column, rib cage, hyoid bone
– Appendicular Skeleton
• Bones of limbs and the limb girdles
– Further Classified by Shape
•
•
•
•
•
•
Long- bones of limbs
Short- cube shaped bones of digits
Flat - skull
Round- like the patella
Irregular- like vertebrae and facial bones
All bones have depressions and protruberances (processes)
for attachment of muscles
The Skeleton
19.2 Bones of the Skeleton
• The Axial Skeleton
– The Skull
• The skull consists of the cranium (braincase) and the facial
bones
– Cranial Bones of the Skull
• Protect the brain
• Incomplete ossification in infants- fontanels
• Bones are named for the lobes of the brain
–
–
–
–
Frontal- forms forehead
Parietal-sides of braincase
Temporal-below parietals, has external auditory canal
Occipital-base of the skull; foramen magnum for passage of
spinal cord
– Sphenoid bone-floor of cranium; articulates with most of the
other bones and forms part of the orbits
– Ethmoid bone-forms orbits and the nasal septum
Bones of the Skull
19.2 Bones of the Skeleton
• The Axial Skeleton
– Facial bones
• Mandible- lower jaw; only movable bone of the skull
• Maxillae- upper jaw; also forms anterior hard palate
• Zygomatic bones- cheekbones
• Nasal bones- bridge of nose
• Lacrimal bones- contain the nasolacrimal canals
• Temporal and facial bones are also bones of the cranium
which contribute to the face
19.2 Bones of the Skeleton
• The Axial Skeleton
– Hyoid bone
• The hyoid is the only bone in the body which does
not articulate with another bone
• Has a membranous attachment to the larynx, and
to the temporals by muscles and ligaments
• Anchors the tongue and attaches muscles
associated with swallowing
Bones of the Face
and the Hyoid
19.2 Bones of the Skeleton
• The Axial Skeleton
– Vertebral column
• 33 vertebrae with 4 curvatures
• Spinal cord passes through the vertebral canal and spinal
nerves exit through intervertebral foramina
• Types of vertebrae
– 7 Cervical vertebrae-first 2 are specialized
» Atlas- articulates with the skull
» Axis- allows rotation of the skull
– 12 Thoracic vertebrae- have articular facets to articulate with
the ribs; prominent spinous processes
– 5 Lumbar vertebrae- large bodies and thick processes
– 5 Sacral vertebrae- fused to form the sacrum
– 3-5 Coccyx- coccygeal vertebrae form “tailbone”
19.2 Bones of the Skeleton
• The Axial Skeleton
– Intervertebral disks
• Composed of fibrocartilage
• Absorb shock and allow flexibility
• Can herniate and rupture
– Puts pressure on the spinal cord
The Vertebral Column
19.2 Bones of the Skeleton
• The Axial Skeleton
– The Rib Cage
• Ribs- each originates at a thoracic vertebra and proceeds to
anterior thoracic wall
– True ribs-7 upper pair which articulate directly with sternum by
means of a costal cartilage
– False ribs- next 3 pair which first join in a common cartilage and
then to the sternum
– Floating ribs- last 2 pair do not articulate with the sternum at all
• Sternum- lies in midline
– Manubrium- articulates with clavicle and first pair of ribs
– Body or blade- point of junction between manubrium and body
is an important landmark-identifies second pair of ribs
» Allows counting of ribs to determine apex of heart
– Xiphoid- has a process for muscle attachment
Thoracic Vertebrae and
the Rib Cage
19.2 Bones of the Skeleton
• Appendicular Skeleton
– Pectoral Girdle
• Clavicle- collar bone: articulates with sternum and acromion
process of scapula
• Scapula- glenoid fossa articulates with humerus
– Coracoid process- point of muscle attachment
– Spine- muscle attachment
19.2 Bones of the Skeleton
• Appendicular Skeleton
– Upper Limb
• Humerus- Upper arm bone
• Radius- bone of forearm
• Ulna- bone of forearm
• Carpal bones- bones of the wrist
• Metacarpals- 5 bones that form the palm
• Phalanges- bones of the digits
Bones of the Pectoral girdle
and Upper Limb
19.2 Bones of the Skeleton
• Appendicular Skeleton
– Pelvic Girdle
• Pelvis is composed of pelvic girdle, sacrum, and
coccyx
• Protects internal organs, bears weight of body,
serves as point of attachment for lower limbs
• 2 coxal bones each composed of 3 fused bones
– Ilium- largest of the three
– Ischium-has a posterior spine called the ischial spine
– Pubis-fused with opposite side at pubic symphysis
19.2 Bones of the Skeleton
• Appendicular Skeleton
– Lower limb
• Femur- largest bone
• Tibia-weight bearing bone of lower leg
• Patella- kneecap
• Fibula- smaller bone on lateral side of tibia;
• Tarsals- ankle bones
– Calcaneus- heel bone
• Metatarsals- instep of foot
• Phalanges- digits
Bones of the Pelvic Girdle
and Lower Limb
19.2 Bones of the Skeleton
• Articulations (Joints)
– Fibrous- immovable
• Sutures between bones of skull
– Cartilaginous- slightly movable
• Connected by hyaline cartilage
– Ribs / sternum
• Connected by fibrocartilage
– Intervertebral discs
19.2 Bones of the Skeleton
• Articulations
– Synovial- freely movable
•
•
•
•
Bones are separated by a cavity
Ligaments holds two bones in place
Tendons help to stabilize the joint
Synovial membrane- lines joint capsule
– Types of Synovial Joints
• Hinge joints- permit movement in one direction only
– Ex: knee
• Pivot joint- permit only rotational movement
– Ex: joint between radius and ulna
• Ball and socket joints- permit movement in all planes
– Ex: hip joint
Knee Joint
19.3 Skeletal Muscles
• Skeletal Muscles Work in Pairs
– Skeletal muscles are voluntary
– Skeletal muscles are covered by layers of connective
tissue called fascia
– Tendons attach skeletal muscles to bones
– The origin of a muscle is on the stationary bone
– The insertion of a muscle is on the bone that moves
19.3 Skeletal Muscles
• Antagonistic pairs of
muscles bring about
movement in opposite
directions.
19.3 Skeletal Muscles
• Major Skeletal Muscles
– Skeletal muscles are named based on the following
characteristics:
•
•
•
•
Size- “maximus”- largest ex: gluteus maximus
Shape- ex: deltoid has shape (triangle) of the Greek letter
Location- ex: frontalis overlies the frontal bone
Direction of muscle fibers- “rectus” means straight
– Ex: rectus abdominis
• Number of attachments- “biceps” means two ex: biceps
brachii
• Action- ex: extensor digitorum extends the digits
19.3 Skeletal Muscles
19.4 Mechanisms of Muscle Fiber
Contraction
19.4 Mechanisms of Muscle Fiber
Contraction
19.4 Mechanisms of Muscle Fiber
Contraction
• Myofibrils and Sarcomeres
– Myofibrils are cylindrical and run the length of the
muscle fiber
– Striated appearance due to arrangement of
contractile filaments
• Unit of contraction- sarcomere
• Extends from Z line to Z line
• Contains two types of contractile proteins
– Actin- thin filament
– Myosin- thick filament
• I band- light colored band of sarcomere, contains only actin
• A band has overlapping actin and myosin
• H band- contains only myosin
19.4 Mechanisms of Muscle Fiber
Contraction
• Contractile Myofilaments
– Myosin
• Each myosin molecule is shaped like a golf club
– Straight portion ending in a double globular head or crossbridge
– Cross bridges occur on each side of a sarcomere but not in the
middle
– Actin
• Consists of two intertwining actin filaments
• Tropomyosin and troponin are associated proteins
19.4 Mechanisms of Muscle Fiber
Contraction
• Sliding Filaments
– Upon stimulation, sarcoplasma depolarizes and an action
potential spreads along the membrane
– AP travels down T tubules into muscle fiber
– Calcium is released from the sarcoplasmic reticulum
– Sarcomeres within the myofibrils shorten- causes contraction of
the muscle fiber
• Actin filaments slide past the myosin filaments and approach one
another
• I bands shorten and the H zone disappears
• ATP supplies the energy
• Myosin filaments break down ATP and have crossbridges that pull
the actin filaments toward the center of the sarcomere
Skeletal Muscle Fiber Structure
and Function
19.4 Mechanisms of Muscle Fiber
Contraction
• Skeletal Muscle Contraction
– One motor neuron can synapse with few or many
muscle fibers in a muscle
– Each axon has axon branches that end in axon
terminal
– Axon terminal contains synaptic vesicles filled with
acetylcholine (ACh)
– When the nerve impulse reaches the end of an axon,
ACh is released into the synaptic cleft
– Ach diffuses across the cleft and binds to receptors in
the sarcolemma
19.4 Mechanisms of Muscle Fiber
Contraction
• Skeletal Muscle Contraction
– The sarcolemma generates impulses that spread over
itself and down T-tubules to the sarcoplasmic
reticulum.
– Sarcoplasmic reticulum releases calcium and the
filaments within the sarcomeres to slide past one
another.
– Sarcomere contraction causes myofibril contraction,
resulting in the contraction of a muscle fiber and
eventually the entire muscle.
Neuromuscular Junction
19.4 Mechanisms of Muscle Fiber
Contraction
• The Molecular Mechanism of Contraction
– Tropomyosin threads wind through actin
– Troponin is located at intervals along actin
– When calcium ions are released, they bind to troponin
• Causes tropomyosin threads to shift position
– Globular heads of myosin have ATP binding sites
• ATPase splits ATP to ADP and P
• Heads now bind to sites on actin
• ADP and P are released from myosin and the crossbridges
change positions-power stroke
– This causes the actin filaments to slide (contraction)
– Relaxation occurs when impulses stop and calcium is
actively transported into the sarcoplasmic reticulum
The Molecular Mechanism
of Contraction
19.4 Mechanisms of Muscle Fiber
Contraction
• Energy for Muscle Contraction
– Muscles acquire new ATP in three ways
• Creatine phosphate (anaerobic)
• Cell respiration (aerobic)
• Fermentation (anaerobic)
19.4 Mechanisms of Muscle Fiber
Contraction
• Energy for Muscle Contraction
– Creatine Phosphate Breakdown
•
•
•
•
High energy compound, builds up at rest
Fastest way to make ATP available for muscle cells
Can provide energy for about 8 seconds of intense activity
Creatine phosphate is rebuilt by transferring a phosphate
group from ATP to creatine
19.4 Mechanisms of Muscle Fiber
Contraction
• Energy for Muscle Contraction
– Cellular Respiration
• Provides most of the energy for muscle contraction
• Muscle cell can use glucose from glycogen and fatty acids
from fat in cell respiration pathway
• Occurs in mitochondria and requires oxygen
• Muscle cell has myoglobin-has higher affinity for oxygen than
hemoglobin
– Allows temporary storage of oxygen
• End products
– Carbon dioxide removed by lungs
– Water is removed by bloodstream
– Heat-is generated as a by-product and used to keep body
warm
19.4 Mechanisms of Muscle Fiber
Contraction
• Energy for Muscle Contraction
– Fermentation
• Supplies ATP without oxygen
• Glucose is broken down to lactic acid (lactic acid)
• Lactic acid builds up and makes cytoplasm more acidic
• If fermentation continues for more than 2-3 minutes cramping
and fatigue occur
– From lack of ATP to pump calcium back into sarcoplasmic
reticulum
19.4 Mechanisms of Muscle Fiber
Contraction
• Energy for Muscle Contraction
– Oxygen Debt
• Occurs when a muscle uses creatine phosphate of
fermentation to supply its energy needs
• Important so that blood glucose can be spared and used by
the brain
• Repaying an oxygen debt
– Replenish creatine supplies
– Disposal of lactate
» Metabolized in mitochondria or sent to the liver to
reconstruct glycogen
19.5 Whole Muscle Contraction
• In the Laboratory
– A single muscle fiber contracts completely along its
length in response to a stimulus- all or none law
– Whole muscle can contract to various degrees
– A myogram is a visible pattern of contraction recorded
in the laboratory
– Muscle Twitch: Response of a muscle to a single
threshold stimulus
• Latent Period: from stimulus to onset of contraction
• Contraction Period: while muscle is shortening
• Relaxation Period: muscle returns to resting length
19.5 Whole Muscle Contraction
• In the Laboratory
– Whole Muscle Contraction
• Unlike a single fiber, whole muscle exhibits degrees of
contraction
– Stronger stimulation causes more fibers to contract
• Tetanus- response to a rapid series of stimuli
– Muscle can respond to the next stimulus without relaxing
completely
• Summation- increased muscle contraction until a maximum
sustained contraction (tetanus) is reached
– Myogram no longer show individual twitches
– Twitches are fused together
– Tetanus continues until muscle fatigues from depletion of
energy reserves
Physiology of Skeletal Muscle
Contraction
19.5 Whole Muscle Contraction
• In the Body
– A motor unit is a nerve fiber together with all the
muscle fibers it innervates.
– As the intensity of nervous stimulation increases,
more motor units are activated.
– Some muscle fibers are contracting while others are
relaxing.
– Even when muscles appear to be at rest, some fibers
are always contracting (muscle tone)
19.5 Whole Muscle Contraction
• Athletics and Muscle Contraction
– Exercise and Size of Muscles
• Muscles that are not used decrease in size (atrophy)
• If stimulation is not restored, muscle fibers are gradually
replaced by fat and fibrous tissue.
• Forceful activity over prolonged period causes muscle to
increase in size
– Hypertrophy-occurs only if muscle contracts to at 75% of
maximum tension
– Increase in number of myofibrils within fibers causes
hypertrophy
19.5 Whole Muscle Contraction
• Athletics and Muscle Contraction
– Slow-Twitch and Fast-Twitch Muscle Fibers
• Slow-twitch fibers
–
–
–
–
–
Steadier “tug” and more endurance
Produce most energy aerobically
Have many mitochondria and are dark in color from myoglobin
Have low maximum tension which develops slowly
Substantial reserves of glycogen and fat
• Fast-twitch fibers
– Anaerobic
– Develop maximum tension rapidly
– Dependence on anaerobic energy leaves them vulnerable to
accumulation of lactic acid and fatigue
Slow-Twitch and Fast-Twitch
Muscle Fibers
19.6 Disorders of the
Musculoskeletal System
• Disorders of the
Skeletons and Joints
– Fractured Bones
• Greenstick fractures
• Stress fractures
• Compound Fractures
19.6 Disorders of the
Musculoskeletal System
• Disorders of the
Skeletons and Joints
– Osteoporosis
• Bones lose mass and
mineral content
• Leads to an increase
risk of fractures
19.6 Disorders of the
Musculoskeletal System
• Disorders of the
Skeletons and Joints
– Arthritis
• Osteoarthritis
– Degenerative joint
disease (cartilage)
• Rheumatoid arthritis
– Autoimmune disease
– Joints and other
tissues are attacked
19.6 Disorders of the
Musculoskeletal System
• Disorders of the Muscles
– Fibromyalgia
• Severe pain in neck, shoulders, back, and hips
• Chronic fatigue
• May be due to low levels of serotonin or other
neurotransmitters involved with pain perception
19.6 Disorders of the
Musculoskeletal System
• Disorders of the Muscles
– Muscular Dystrophies (MD)
• Different forms have various times of onset
• Duchene Muscular Dystrophy
– Most common form
– Abnormal gene that causes muscle weakness
– Affects mainly boys