Download Muscular System - Mr Thomsen ASB

MUSCULAR SYSTEM
Pau Junyent & Aurora Nieto
What are muscles? I








contractile tissue found in animals
over 650 muscles
half the weight of the human body
produce movement & body heat
skeletal, smooth and cardiac
ability to contract and conduct electrical impulses
voluntary (biceps) or involuntary(lungs)
striated or smooth
What are muscles? II

Rigor Mortis: stiffening body after death,
caused by calcium in the muscle






contract & relax; NOT stretch
made up of elastic tissue
need: Oxygen and Blood
Antagonist muscles: pair of muscles that do opposite
things from one another
Elasticity: the ability to return to original shape
Flexion: ability to bend a joint
Differences


Different functions
Appearance
- skeletal muscle: striated (striped)
- cardiac muscle: striated but stripes less
organized. contain branches, allow rapid
communication
- smooth muscle: composed of
cells with dark nuclei;
not striated
Smooth Muscle I









Involuntary muscle
Found in hollow parts of the body
Stimulated by the nervous system
Two groups: single-unit and multiunit
Single-unit: rapid and simple contractions
Multiunit: contractions depend on the nervous system
Found in: Walls, arteries, veins, urinary bladder,
lymphatic vessels, uterus, respiratory tract, iris, etc…
Structure and function the same for every all organs
Said to be in charge of ‘housekeeping’ functions
Smooth Muscle II





Contracts everything at once
Cytoplasm is filled with myosin and actin molecules
Myosin: ATP-dependent motor protein
Actin: Protein found in all eukaryote cells
Contraction caused by sliding actin and myosin
filaments
Skeletal Muscle I






Produce movement & supports the skeleton
Voluntary muscle
Controlled by the nervous system
Attached to bones by tendons
Made up of muscle fibers (myoblasts)
Cartilage: connective tissue found
in joints
Skeletal Muscle II



Two groups: Type I and type II
Type I: red, presence of oxygen, for endurance and
slow fatigue
Type II: white, absence of myoglobin, reliance on
glycolytic enzymes, used shortly, use oxidative and
anaerobic metabolism, fast fatigue
Skeletal Muscle III – Categorized I




Categorized not only by color but by arragement of
fascicles
Parallel, convergent, pennate, sphinter
Parallel muscles:
 fascicles run parallel to the direction of the muscle
 most skeletal muscle (triceps, biceps)
Convergent muscles:
 Fibers come out from a common point.
 Cover larges surfaces.
 Allow a lot of movement (pectoralis major)
Skeletal Muscle III – Categorized II


Pennate muscles:
 1 or more tendons run through the muscle
 the fascicles form a slanted angle to the tendons
 greater amount of muscle fibers = more tension
(Rectus Femoris)
Sphinter muscles (circular) :
 arranged around an opening
 when muscle contracts, opening gets smaller.
 at the entrances and exits of passage ways
Most Important Skeletal Muscles
Pectoralis Major:
 Thick, fan-shaped muscle
 At the front (chest) of human body
 Flexes chest area
Gluteus Maximus:
 Largest and most superfcial of gluteal muscles
 Shape and appearance of buttocks
 Flexes thigh joint
Differences (Tendon & Ligament)


Ligaments:
 connect bone to bone
 help to stabilize joints
 long, stringy collagen
 Slightly elastic
 Stretched to gradually increase flexibility.
Tendon:
 connects muscle to bone
 tough, flexible
 attached to the skeletal muscles
 intermediaries between the muscles
Cardiac Muscle I







Involuntary or voluntary muscle
Heart
Send blood to all the body by using contraction
Cardiomyocytes have 1-4 nuclei
Cordinated contractions
Blood is sent to clean body from waste products and
keep the body active
Highly resistant to fatigue
Cardiac Muscle II




Needs a lot of calcium
Largest number of mitochondria
Cardiac muscles contract to squeeze blood out
Relaxes to fill the heart with blood
Muscle Regeneration






Occurs when a muscle is stretched or torn (muscle
strain)
Muscle breaks when the stress limit is trespassed
Provides more strength and larger size
Regenerates when the body rest
Regeneration will occur no matter how old
Satellite cells fuse with the broken fibers
Video

http://www.youtube.com/watch?v=ren_IQPOhJc