Muscles, Protection, Support, and MovementTristan 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 bodyoHumans have an "endoskeleton" rather than an "exoskeleton" like arthropods; no molting needed•Protects vital internal organsoSkull protects brain, rib cage protects heart and lungs, vertebrae protect spinal cord•Provides sites for muscle attachment•An important storage reservoir for ionsoAll bones have a matrix of calcium phosphate•Produces blood cellsoBlood cells and blood elements produced in red bone marrow in skull, ribs, sternum, pelvis, and long bones

Bones (cont.)

•Born with about 350 bones; fuse to form around 206 by adulthood

http://www.teachpe.com/images/anatomy/skeleton.jpg

Invertebrate Skeletons

•Cnidarians, flatworms, roundworms, and annelids have a hydrostatic skeletonoGastrovascular cavity or fluid-filled coelomResist muscle contraction, resulting in movementAnalogous to a garden hose stiffening when water flows throughAllows organism to move and change shape

http://www.emc.maricopa.edu/faculty/farabee/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 thicknessoDecreases available space for internal organs•Exoskeleton of mollusc grows with organism•Arthropods must molt when exoskeleton becomes too smalloSuffer a period when new one must dry and form

Nonliving Exoskeletons

•The exoskeletons of molluscs and arthropods are nonlivingoMollusc shells grow with the organism, but are still acellularGrow through secretion of more material by organism•Arthropods have exoskeleton of chitin (a nitrogenous polysaccharide)oProduced and dried once; does not continue growing with organismArthropods must molt as a result

Nonliving vs. Living Skeletons

•Echinoderms and vertebrates have endoskeletons•Echinoderms' are nonlivingoComposed of spicules and plates of calcium carbonate embedded in living tissue

•Vertebrates' are living tissueoOffers many benefitsGrows with organism, molting not requiredSupports high weight without limiting spaceProtected by external soft tissueJointed, allowing complex movements

Vertebrate Skeleton

•Two components of the vertebrate skeleton:oAxial skeletonoAppendicular skeleton

http://upload.wikimedia.org/wikipedia/commons/thumb/8/8b/Axial_skeleton_diagram.svg/250px-Axial_skeleton_diagram.svg.png

http://en.wikipedia.org/wiki/File:Appendicular_skeleton_diagram.svg

Axial Skeleton

•Lies in middle of the bodyoSkull, vertebral column, thoracic cage, sacrum, coccyxTotal of 80 bones•Skull protects brainoCranium and facial bonesCranium 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 cordoDirectly 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 boneoOsteoblasts 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 bonesDeterioration of osteoblasts leads to osteoporisis

Muscles

Role of Muscles

•Three types of muscle tissue in humans:oSmoothoCardiacoSkeletal•Skeletal muscle (striated voluntary muscle) is probably of greatest obvious importance to most peopleoImportant in maintaining postureoProvides supportoAllows movementoMaintains homeostasis/body temperatureContraction 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/Muscle

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?

• Myosin breaks down ATPo 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 filamentso most efficient way for muscles

How do Muscles Get Their Energy? (cont.)

• When all creatine-P is expended, fermentation produces ATP sans oxygeno builds lactate

muscle ache and fatigue are the result• We do deep breathing after exercise to metabolize

lactate and restores cellso 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

So This Energy Process Means:

• Regular exerciseo Increases mitochondria for ATP process

Less fermentation reliance• Less lactate produced, less oxygen

debto Reduced fatigue: increased

fitness/endurance

Muscles can be Fast or Slow

• 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

• Fast Twitch Muscles (Type II)o Less efficient with resperationo Has less cappilaries

This explains its paler coloro Stronger than slow twitcho Certain types are anaerobic, explaining why they tire

quickly

Smooth Cardiac and Striated Muscles Respond Differently

• Skeletal muscles are voluntaryo We can willingly control themo React through conscious impulses from the brain

• Smooth muscles are involuntaryo Automatically controlled by our medulla oblongatao Found in stomachs and bladders

• Cardiac muscles are also involuntaryo Controlled by medulla oblongatao Found only in the hearto 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

• Connects muscles to boneso 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 jointoLined by synovial membraneProduces 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 bodyo Muscles control the direction of movement

• Primarily classified in three groupso No mobilityo Little mobilityo Free movement

Immovable Joints

• Also called synarthrosis• Joined fibrous joints,

there is almost no motionpermitted

• 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 cavityo Provides a fluid that decreases friction

• Can be strengthened by ligaments

Human Elbow Outlined

• Synovial Cavityo 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 thesynovial cavity

o Protects the space• Cartilage

o Helps lube up an area

Hip vs. Knee Joint Movement

http://www.youtube.com/watch?v=w4LSWmJnniw

• Ball-and-socket (hip joint)

• Hinge (knee, elbow, fingers)

• More in-depth::http://www.youtube.com/watch?v=ZWcdMj8wRos

Joint Diseases

• Rheumatoid Arthritiso The body creates an inflammatory response against

jointso Causes swelling of the synovium

• Osteoarthrituso Caused by the loss of cartilageo 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 epitheliumIt covers our entire body

• In some invertebrates, the skin secretes a cuticlean 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