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How Animals Move. Chapter 21. Pumping Up Muscles. Androstenedione Intermediate in testosterone and estrogen synthesis pathways Taken as dietary supplement Doesn’t help add muscle Does have negative side effects. Pumping Up Muscles. Creatine phosphate Short chain of amino acids

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pumping up muscles
Pumping Up Muscles
  • Androstenedione
    • Intermediate in testosterone and estrogen synthesis pathways
    • Taken as dietary supplement
    • Doesn’t help add muscle
    • Does have negative side effects
pumping up muscles1
Pumping Up Muscles
  • Creatine phosphate
    • Short chain of amino acids
    • Donates phosphate to ATP when muscles need quick energy
    • Does enhance performance in sports that require short bursts of energy
    • Long-term effects unknown
3 types of skeletons
3 Types of Skeletons

feed me!

  • Hydrostatic skeleton
  • Exoskeleton

resting

3 types of skeletons1
3 Types of Skeletons

3. Endoskeleton (vertebrates)

Generalized mammal

pelvic girdle

pectoral girdle

slide7

Skull bones

Pectoral girdle

and upper limb bones

a

d

CRANIAL BONES

FACIAL BONES

CLAVICLE

SCAPULA

Rib Cage

b

STERNUM

HUMERUS

RADIUS

RIBS

CARPALS

Vertebral Column

c

ULNA

PHALANGES

VERTEBRAE

METACARPALS

INTERVERTEBRAL DISKS

Pelvic girdle

and lower limb bones

e

PELVIC GIRDLE

FEMUR

PATELLA

TIBIA

ligament bridging a knee joint, side view, midsection

FIBULA

TARSALS

METATARSALS

PHALANGES

Fig. 21-3, p.351

functions of bones
Functions of Bones
  • Interact with muscle to enable movement
  • Support and anchor muscles
  • Enclose and protect internal organs
  • Store calcium and phosphorus
  • Produce blood cells
long bone structure
Long Bone Structure
  • Compact bone
  • Spongy bone
  • Central cavity contains yellow marrow

nutrient canal

central cavity (contains yellow

marrow)

compact bone tissue

spongy bone

tissue

compact bone structure
Compact Bone Structure
  • Compact bone consists of many dense, cylindrical layers surrounding canals

cylindrical layers

blood vessel

outer layer of

dense connective

tissue

spongy bonetissue

compact bone tissue

bone marrow
Bone Marrow
  • Yellow marrow
    • Fills the cavities of adult long bones
    • Is largely fat
  • Red marrow
    • Occurs in spongy bone of some bones
    • Produces blood cells
bone mass
Bone Mass
  • In adults, bone building and bone breakdown continue constantly
  • Osteoblast secretions form bone
  • Osteoclasts enzymes degrade bone
  • Adding and removing minerals adjusts bone strength and helps maintain blood calcium levels
bone density
Bone Density
  • Exercise can increase bone density
  • Osteoporosis: Decrease in bone density
    • May occur when the action of osteoclasts outpaces that of osteoblasts
    • May also occur as a result of inability to absorb calcium
where bones meet
Where Bones Meet
  • Joints: Areas of contact or near contact between bones
  • Ligaments: Straps of connective tissue at joints
  • Arthritis: Joint damage or inflammation
    • Osteoarthritis
    • Rheumatoid arthritis
skeletal muscle
Skeletal Muscle
  • Bundles of muscle fibers
  • Tendons attach muscles to bone
  • Lever system
  • Opposing muscle groups

biceps

triceps

skeletal muscle contraction
Skeletal Muscle Contraction
  • A muscle is made up of bundles of muscle fibers
  • Muscle fiber contains cross-banded myofibrils

myofibril

sarcomere
Sarcomere

Myofibril is made up of thick and thin filaments arranged in sarcomeres

sarcomere

sarcomere

sarcomere

sarcomere

Z band

Z band

Z band

muscle microfilaments
Muscle Microfilaments

Thin filaments

  • Two actin strands twisted together
  • Globular proteins
  • Parallel with myofibril
  • Thick filaments
  • Myosin
  • Motor protein
  • Tail and double head
sliding filament model
Sliding-Filament Model
  • Myosin heads attach to actin filaments
  • Myosin heads tilt toward sarcomere center, pulling actin with them
sliding filament model1
Sliding-Filament Model

When actin filaments are pulled inward, toward sarcomere center, sarcomere shortens

Filaments themselves do not shorten

contraction requires calcium
Contraction Requires Calcium
  • Skeletal muscles contract in response to signals from motor neurons
  • Signals release calcium from sarcoplasmic reticulum
  • Calcium allows actin and myosin to bridge
contraction requires energy
Contraction Requires Energy
  • Muscle cells require huge amounts of ATP energy to power contraction
  • Cells store only small amounts of ATP
  • Three pathways supply ATP to power muscle contraction
atp for contraction
ATP for Contraction

ADP + Pi

pathway 1

dephosphorylation

creatine phosphate

relaxation

contraction

creatine

pathway 2

aerobic

respiration

pathway 3

glycolysis

alone

glucose from bloodstream and from glycogen break down in cells

oxygen

motor unit
Motor Unit
  • One neuron and all muscle fibers it controls
  • When a motor neuron is stimulated, all fibers in muscle unit contract simultaneously, producing muscle twitch
  • Rapid, repeated stimulus of motor unit produces tetanus
twitch and tetanus

peak

Twitch and Tetanus

relaxation

stimulus

contraction starts

time

number of stimuli per second

number of stimuli per second

tetanic

contraction

twitch

repeated stimulation

muscle tension
Muscle Tension
  • Mechanical force exerted on an object by a contracting muscle
  • For a muscle to shorten, muscle tension must exceed the load that opposes it
  • Load may be the weight of an object or pull of gravity on muscle
two types of contraction
Two Types of Contraction

Muscle contracts but can’t shorten

Muscle shortens as it contracts

Isotonic contraction:

Load is less than muscle’s

peak capacity

Isometric contraction: Load is greater than muscle’s peak capacity

infection and motor neurons
Infection and Motor Neurons
  • Bacterial toxins block motor neuron control
    • Clostridium botulinum, botulism
    • Clostridium tetani, tetanus
muscle fatigue
Muscle Fatigue
  • Inability to maintain muscle tension
  • Glycogen is depleted after a period of tetanic contraction
  • Requires recovery time
muscular dystrophies
Muscular Dystrophies
  • Genetic disorders in which muscles weaken and degenerate
  • Duchenne muscular dystrophy
    • Defective protein in muscle plasma membrane prevents normal binding of actin filaments to Z band
  • Myotonic muscular dystrophy
exercise
Exercise
  • Aerobic
    • Long duration, low intensity
    • Increases number of mitochondria, number of blood capillaries to all skeletal muscle
  • Strength training
    • Intense, short duration
    • Makes fast-acting muscles form more myofibrils and enzymes for glycolysis
aging
Aging
  • Muscles shrink
  • Number of muscle fibers decreases
  • Slower healing time
  • Aerobic exercise improves fitness and memory