Structural Support and Movement
Chapter 36 Part 1
Impacts, Issues
Pumping Up Muscles
Increasing muscle size and strength with drugs
such as “andro” has unwanted side effects and
can damage other organ systems
36.1 Invertebrate Skeletons
Hydrostatic skeleton
• An enclosed fluid that contracting muscles act
upon (as in sea anemones, earthworms)
Exoskeleton
• A hardened external skeleton found in some
mollusks and all arthropods
Endoskeleton
• An internal skeleton, as in echinoderms
Hydrostatic Skeleton: Sea Anemone
Fig. 36-2a, p. 618
mouth
gastro-
vascular
cavity; the
mouth can
close and trap
fluid inside
this cavity
Hydrostatic Skeleton: Earthworm
Exoskeleton: Fly
Fig. 36-4, p. 619
longitudinal
muscle contractslongitudinal
muscle relaxes
vertical muscle
relaxes
vertical muscle
contracts
A Wings pivot down as the
relaxation of vertical muscle and
the contraction of longitudinal
muscle pulls in sides of thorax.
B Wings pivot up when the
contraction of vertical muscle
and relaxation of longitudinal
muscle flattens the thorax.
thorax
Exoskeleton: Spider
36.1 Key Concepts
Invertebrate Skeletons
Contractile force exerted against a skeleton moves animal bodies
In many invertebrates a fluid-filled body cavity is a hydrostatic skeleton
Others have an exoskeleton of hard structures at the body surface
Still others have a hard internal skeleton, or endoskeleton
36.2 The Vertebrate Endoskeleton
All vertebrates have an endoskeleton
• Usually consists primarily of bones
• Supports the body, site of muscle attachment
• Protects the spinal cord
The vertebral column (backbone) is made up of
individual vertebrae separated by
intervertebral disks made of cartilage
Axial and Appendicular Skeleton
Axial skeleton
• Skull
• Vertebral column
• Ribs
Appendicular skeleton
• Pectoral girdle
• Pelvic girdle
• Limbs
Skeletal Elements: Fish and Reptile
Fig. 36-7a, p. 620
vertebral column
pectoral girdle
pelvic girdle
Fig. 36-7b, p. 620
rib cage
vertebral
columnskull bones
pelvic girdle
pectoral girdle
The Human Skeleton
Some features of the human skeleton are
adaptations to upright posture and walking
• Foramen magnum at the base of the skull allows
brain and spinal cord to connect
• Vertebrae stacked one above the other in an S
curve
Bones of the Human Skeleton
Fig. 36-8, p. 621
A Skull bones
CRANIAL BONES
D Pectoral girdle and upper limb bones
FACIAL BONES
B Rib cage
CLAVICLE (collarbone)
SCAPULA (shoulder blade)STERNUM (breastbone) HUMERUS (upper arm bone)RIBS (twelve pairs)
RADIUS (forearm bone)C Vertebral column, or backbone CARPALS (wrist bones)
ULNA (forearm bone)
VERTEBRAE 12
43
5INTERVERTEBRAL DISKS
METACARPALS (palm bones)
PHALANGES (thumb, finger bones)
E Pelvic girdle and lower limb bones
PELVIC GIRDLE (six fused bones)
FEMUR (thighbone)
PATELLA (kneebone)
ligament bridginga knee joint, side view, midsection
TIBIA (lower leg bone)
FIBULA (lower leg bone)
TARSALS (ankle bones)METATARSALS (sole bones) PHALANGES (toe bones)
36.3 Bone Structure and Function
Bones have a variety of shapes and sizes
• Long bones (arms and legs)
• Flat bones (skull, ribs)
• Short bones (carpals)
The human skeleton has 206 bones ranging
from tiny ear bones to the massive femur
Bone Anatomy
Bones consist of three types of living cells in a
secreted extracellular matrix
• Osteoblasts build bones
• Osteocytes are mature osteoblasts
• Osteoclasts break down bone matrix
Bone cavities contain bone marrow
• Red marrow in spongy bone forms blood cells
• Yellow marrow in long bones is mostly fat
Bone Anatomy: Long Bone
Fig. 36-9a, p. 622
Fig. 36-9a, p. 622
space occupied
by living bone cellblood
vessel
nutrient canal
location of
yellow marrow
compact
bone tissue
spongy
bone
tissue
55 µm
Fig. 36-9b, p. 622
Fig. 36-9b, p. 622
spongy
bone
tissue
compact
bone tissueouter layer
of dense
connective tissueblood vessel
Bone Functions
Bone Formation and Remodeling
The embryonic skeleton consists of cartilage
which is modeled into bone, grows until early
adulthood, and is constantly remodeled
Bones and teeth store the body’s calcium
• Calcitonin slows release of calcium from bones
• Parathyroid hormone releases bone calcium
• Sex hormones encourage bone building
• Cortisol slows bone building
Long Bone Formation
Fig. 36-10, p. 623
Embryo:
cartilage model
of bone forms
Fetus:
blood vessel invades
model; osteoblasts start
producing bone tissue;
marrow cavity forms
Newborn:
remodeling and growth
continue; secondary
bone-forming centers
appear at knobby
ends of bone
Adult:
mature bone
About Osteoporosis
Osteoporosis (“porous bones”)
• When more calcium is removed from bone than is
deposited, bone become brittle and break easily
Proper diet and exercise help keep bones
healthy
Osteoporosis
36.4 Skeletal Joints—Where Bones Meet
Joint
• Area of contact or near contact between bones
Three types of joints
• Fibrous joints (teeth sockets): no movement
• Cartilaginous joints (vertebrae): little movement
• Synovial joints (knee): much movement
Synovial Joints
In synovial joints, bones are separated by a fluid-
filled cavity, padded with cartilage, and held
together by dense connective tissue (ligaments)
Different synovial joints have different movements
• Ball-and-socket joints (shoulder)
• Gliding joints (wrist and ankles)
• Hinged joints (elbows and knees)
Three Types of Joints
Three Types of Joints
Fig. 36-12a, p. 624
fibrous joint attaches
tooth to jawbone
synovial joint (ball and
socket) between humerus
and scapula
cartilaginous joint
between rib and sternum
cartilaginous joint
between adjacent
vertebrae
synovial joint (hinge type)
between humerus and
radius
synovial joint (ball and
socket) between pelvic
girdle and femur
Fig. 36-12b, p. 624
femur
patella
cartilage
ligaments
menisci
tibia
fibula
36.5 Those Aching Joints
We ask a lot of our joints when we engage in
sports, carry out repetitive tasks, or strap on a
pair of high heels
Joint Injuries and Diseases
Common joint injuries
• Sprained ankle; torn cruciate ligaments in knee;
torn meniscus in knee; dislocations
Arthritis (chronic inflammation)
• Osteoarthritis; rheumatoid arthritis; gout
Bursitis (inflammation of a bursa)
36.2-36.5 Key Concepts
Vertebrate Skeletons
Vertebrates have an endoskeleton of cartilage, bone, or both
Bones interact with muscles to move the body; they also protect and support organs, and store minerals
Blood cells form in some bones
A joint is a place where bones meet; there are several kinds
36.6 Skeletal–Muscular Systems
Muscle fibers
• Long, cylindrical cells with multiple nuclei that
hold contractile filaments
Tendons attach skeletal muscle to bone
• Muscle contraction transmits force to bone and
makes it move
Muscles and bones interact as a lever system
• Many skeletal muscles work in opposing pairs
Skeletal–Muscular Action
Fig. 36-14, p. 626
C The first muscle
group in the upper
hindlimb contracts
again and draws it
back toward body.
B An opposing muscle
group attached to the
limb forcefully contracts
and pulls it back. The
contractile force, applied
against the rock, now
propels the frog forward.
A A muscle attached
to each upper hindlimb
contracts and pulls it
slightly forward relative
to main body axis.
Opposing Muscle Groups
Fig. 36-15, p. 626
Triceps
contracts,
pulls the
forelimb
down.
Triceps relaxes.
Biceps contracts at
the same time, and
pulls forelimb up.
At the same
time, biceps
relaxes.
A When the triceps
relaxes and its
opposing partner
(biceps) contracts,
the elbow joint flexes
and the forearm is
pulled upward.
B When the triceps
contracts and the
biceps relaxes, the
forearm is extended
downward.
Muscles and Tendons
Muscles and Tendons
Fig. 36-16a, p. 627
TRICEPS BRACHIIStraightens the forearm at elbow
BICEPS BRACHIIBends the forearm at the elbow
PECTORALIS MAJORDraws the arm forward and in toward the body
DELTOIDRaises the armSERRATUS ANTERIOR
Draws shoulder blade forward, helps raise arm, assists in pushes
TRAPEZIUSLifts the shoulder blade, braces the shoulder, draws the head backEXTERNAL OBLIQUE
Compresses the abdomen, assists in lateral rotation of the torso
LATISSIMUS DORSIRotates and draws the arm backward and toward the bodyRECTUS ABDOMINIS
Depresses the thoracic (chest) cavity, compresses the abdomen, bends the backbone
GLUTEUS MAXIMUS
ADDUCTOR LONGUS
Extends and rotates the thigh outward when walking, running, and climbingFlexes, laterally rotates,
and draws the thighs toward the body
SARTORIUS
BICEPS FEMORIS
Bends the thigh at the hip, bends lower leg at the knee, rotates the thigh in an outward direction
(Hamstring muscle) Draws thigh backward, bends the knee
QUADRICEPS FEMORISSet of four muscles that flex the thigh at the hip, extend the leg at knee
GASTROCNEMIUS
TIBIALIS ANTERIOR
Bends the lower leg at the knee when walking, extends the foot when jumping
Flexes the foot toward the shin
Achilles tendon
Fig. 36-16b, p. 627
muscle
tendon
bursae
synovial
cavity
36.6 Key Concepts
The Muscle–Bone Partnership
Skeletal muscles are bundles of muscle fibers
that interact with bones and with one another
Some cause movements by working as pairs or
groups; others oppose or reverse the action of a
partner muscle
Tendons attach skeletal muscles to bones