Muscles,
Protection,
Support, and
Movement
Tristan Beasley-Painter and
Nicholas Ravn
Structures to be Discussed
•Bones
•Muscles
•Ligaments
•Tendons
•Joints
•Nerves
Bones
Role of Bones
•Provide a rigid structure to support body
oHumans
have an "endoskeleton" rather than an
"exoskeleton" like arthropods; no molting needed
Protects vital internal organs
oSkull protects brain, rib cage protects heart and lungs,
vertebrae protect spinal cord
Provides sites for muscle attachment
An important storage reservoir for ions
oAll bones have a matrix of calcium phosphate
Produces blood cells
oBlood cells and blood elements produced in red bone
marrow in skull, ribs, sternum, pelvis, and long bones
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Bones (cont.)
•Born with about 350 bones; fuse to form around 206 by adulthood
http://www.teach
pe.com/images/
anatomy/skeleto
n.jpg
Invertebrate Skeletons
•Cnidarians, flatworms, roundworms, and annelids have a
hydrostatic skeleton
oGastrovascular cavity or fluid-filled coelom
Resist muscle contraction, resulting in movement
Analogous to a garden hose stiffening when water flows
through
Allows organism to move and change shape
http://www.emc.maric
opa.edu/faculty/farab
ee/biobk/hydroskel2.
gif
Invertebrate Skeletons (cont.)
•Molluscs and arthropods typically have exoskeletons
(external skeletons)
oComposed of calcium carbonate (molluscs) or chitin
(arthropods)
Provide protection and muscle attachment points like an
internal skeleton
Strength improved through thickness
oDecreases available space for internal organs
Exoskeleton of mollusc grows with organism
Arthropods must molt when exoskeleton becomes too
small
oSuffer a period when new one must dry and form
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Nonliving Exoskeletons
•The exoskeletons of molluscs and arthropods are
nonliving
oMollusc shells grow with the organism, but are still
acellular
Grow through secretion of more material by organism
Arthropods have exoskeleton of chitin (a nitrogenous
polysaccharide)
oProduced and dried once; does not continue growing with
organism
Arthropods must molt as a result
•
Nonliving vs. Living Skeletons
•Echinoderms and vertebrates have endoskeletons
•Echinoderms' are nonliving
oComposed
of spicules and plates of calcium carbonate
embedded in living tissue
•Vertebrates' are living tissue
oOffers many benefits
Grows with organism, molting not required
Supports high weight without limiting space
Protected by external soft tissue
Jointed, allowing complex movements
Vertebrate Skeleton
•Two components of the vertebrate skeleton:
oAxial
skeleton
oAppendicular skeleton
http://upload.wikimedia.org/wikipedia/commons/
thumb/8/8b/Axial_skeleton_diagram.svg/250pxAxial_skeleton_diagram.svg.png
http://en.wikipedia.org/wi
ki/File:Appendicular_ske
leton_diagram.svg
Axial Skeleton
•Lies in middle of the body
oSkull, vertebral column,
Total of 80 bones
thoracic cage, sacrum, coccyx
•Skull protects brain
oCranium
and facial bones
Cranium bones have same names as lobes of the brain
(for those psychology students out there)
Vertebral column supports head and trunk and protects
the spinal cord
oDirectly or indirectly serves as an anchor for all other
bones of the skeleton
•
Axial Skeleton (cont.)
•The thoracic vertebrae are those that
are part of the thoracic cage (rib cage)
•The sacrum and coccyx are at the end
of the spine and attach to the pelvis
Bone Growth/Remodeling
•Bone consists of both living tissue and nonliving material
•The living tissue includes blood vessels, nerves, collagen
•Important to growth are osteoblasts (form bone) and
osteoclasts (remove old bone)
oOsteoclasts form in small concentrations to remove an
area of the bone
oOsteoblasts form next, laying down new bone material
over months (affected by nutrition, age, etc.)
This process begins to slow around age 40, leading to
more brittle bones
Deterioration of osteoblasts leads to osteoporisis
Muscles
Role of Muscles
•Three types of muscle tissue in humans:
oSmooth
oCardiac
oSkeletal
•Skeletal muscle (striated voluntary muscle) is probably of
greatest obvious importance to most people
oImportant in maintaining posture
oProvides support
oAllows movement
oMaintains homeostasis/body temperature
Contraction causes ATP breakdown and releases heat
throughout the body
Muscles (cont.)
•Around 700 skeletal muscles
•40% of weight of average human
http://en.wikipedia.org/wiki/Mu
scle
Vertebrate Muscles' Macroscopic
Functions and Physiology
- Muscle cells are quite unique, resulting in them being
called muscle fibers
- They have the normal parts of a cell along with special
components
- Skeletal muscles are muscle fibers in bundles
- “The sarcolemma, or plasma membrane, forms a T
(transverse) system. The T tubules penetrate, or dip down,
into the cell so that they come into contact (but do not fuse)
with expanded portions of modified endoplasmic reticulum,
called the sarcoplasmic reticulum.”
- Store calcium ions
- SR encases myofibrils - what contracts the muscle
Macroscopic Physiology (cont.)
- Myofibrils run along muscle fibers
- Have light and dark bands called striations
- Being why skeletal muscle appears striated
- Contractile units called sarcomeres form these bands as a result of their
protein placement
- When muscles are relaxed, a sarcomere extends between two dark lines
called Z lines
- Two types of protein filaments
- Thick myosin
- Thin actin
“The I band is light colored because it contains only actin filaments attached to
a Z line. The dark regions of the A band contain overlapping actin and myosin
filaments, and its H Zone has only myosin filaments”
http://www.ucl.ac.uk/~sjjgsca/Muscleslidingfilament1.gif
http://www.ucl.ac.uk/~sjjgsca/MuscleSarcomere.gif
Macroscopic Physiology and Sliding Filament Model
- Muscle contraction means that muscles have shortened
- So, muscles can only pull and not push
- Skeletal muscles must work in antagonistic pairs
- For example, biceps contract to bend the arm in and
triceps contract to straighten the arm out
- One of the muscles in the pair must be relaxed to allow
the other to shorten and result in pulling movement
- “When a sarcomere shortens, the actin filaments slide
past the myosin filaments and approach one another. The
causes the I band to shorten and the H zone to nearly or
completely disappear. The movement of actin filaments in
relation to myosin filaments is called the sliding filament
model.”
How do Muscles Get Their Energy?
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Myosin breaks down ATP
o Makes bridges to pull actin toward sarcomere center
ATP provides energy for contraction
o Muscle fibers contain myoglobin (stores oxygen)
 cell respiration does not provide all needed ATP
rely on phosphocreatine (storage)
o anaerobically regenerates ATP with:
 creatine-P + ADP -> ATP + creatine
Occurs during sliding filaments
o most efficient way for muscles
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How do Muscles Get Their Energy? (cont.)
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When all creatine-P is expended, fermentation
produces ATP sans oxygen
o builds lactate
 muscle ache and fatigue are the result
We do deep breathing after exercise to metabolize
lactate and restores cells
o We must "pay back"/"fix" the oxygen debt
o The lactate goes to the liver
 20% broken down into CO2 and H2O
ATP gained from this converts remaining
lactate to glucose
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So This Energy Process Means:
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Regular exercise
o Increases mitochondria for ATP process
 Less fermentation reliance
Less lactate produced, less oxygen
debt
o Reduced fatigue: increased
fitness/endurance
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Muscles can be Fast or Slow
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Muscles are Fast Twitch or Slow Twitch
Slow Twitch Muscles (Type I)
o More efficient with resperation
 Densely packed with capillaries
o Thus they become fatigued much slower
 However they are considered weaker
o They can effectively use fats and carbohydrates
 Aerobic
Muscles can be Fast or Slow
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Fast Twitch Muscles (Type II)
o Less efficient with resperation
o Has less cappilaries
 This explains its paler color
o Stronger than slow twitch
o Certain types are anaerobic, explaining why they tire
quickly
Smooth Cardiac and Striated Muscles Respond Differently
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Skeletal muscles are voluntary
o We can willingly control them
o React through conscious impulses from the brain
Smooth muscles are involuntary
o Automatically controlled by our medulla oblongata
o Found in stomachs and bladders
Cardiac muscles are also involuntary
o Controlled by medulla oblongata
o Found only in the heart
o Structured like that of a skeletal muscle
 It is striated
Look at Electron Micrographs
Skeletal Muscles
Look at Electron Micrographs
Smooth Muscles
Look at Electron Micrographs
Cardiac Muscle
Tendons
Role of Tendons
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Connects muscles to bones
o Works in union with muscles
Without it, muscles would not have
anything to grab onto
Ligaments
Role of Ligaments
•Made of fibrous connective tissue
•Extend across the cavity separating synovial joints (freely movable)
oBind
the two bones of the joint together
•Form a "joint capsule" around the joint
oLined
by synovial membrane
Produces synovial fluid - lubricant for the joint
Joints
Role of Joints
• Located where two bones make contact
• Allows range of movement at key points in the body
o Muscles control the direction of movement
• Primarily classified in three groups
o No mobility
o Little mobility
o Free movement
Immovable Joints
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Also called synarthrosis
Joined fibrous joints,
there is almost no motion
permitted
Key example is the skull
Slightly Movable Joints
• Also known as amphiarthrosis
• Permits a little movement,
but not a large amount
• Mostly cartiliginous
o A cartilage plate protects the bones from grinding on
each other
• Primarily found in the vertebrae
Freely Movable Joints
• Also known as synovial joints
• Permits a large amount of free movement
• Protected by a synovial cavity
o Provides a fluid that decreases friction
• Can be strengthened
by ligaments
Human Elbow Outlined
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Synovial Cavity
o A space that isolates a packet from the rest of the
body
Synovial Fluid
o The liquid that
inhabits said packet
o Reduces friction
Joint Capsule
o The lining of the
synovial cavity
o Protects the space
Cartilage
o Helps lube up an
area
Hip vs. Knee Joint Movement
http://www.youtube.com/watch?v=w4LSWmJnniw
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Ball-and-socket (hip joint)
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Hinge (knee, elbow, fingers)
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More in-depth::
http://www.youtube.com/watch?v=ZWcdMj8wRos
Joint Diseases
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Rheumatoid Arthritis
o The body creates an inflammatory response against
joints
o Causes swelling of the synovium
Osteoarthritus
o Caused by the loss of cartilage
o The lack of a buffer causes the bones to grind on
each other
Both lead to pain and discomfort, however they are
nonfatal
Skin
Role of Skin
• Also known as epithelium
It covers our entire body
• In some invertebrates, the skin secretes a cuticle
an example being oysters
• Epithelium can also secrete lubricants, which facilitate
movement and gas exchange
• Some vertebrates, such as reptiles, have strong
epitheliums, scales, that act like armor
• Bird’s feathers and mammal’s fur act as a way to
insulate and maintain temperature
Nerves
Role of Nerves
• Nerves are what control our muscles
• Somatic nervous system control voluntary muscles
• Autonomic nervous system controls involuntary muscles
Bibliography
•Biology, 10th edition. By Sylvia S. Mader.
•http://www.classbrain.com/artaskcb/publish/article_145.shtml
•http://www.nsbri.org/humanphysspace/focus6/ep_development.html