• Each motion had a limited range of movement. The types and ranges of movement differed.

• Different joints allow rotational movements, angular movements, and gliding movements.

Chapter 10: Movement and

Forces10.1 The skeletal system provides movement and protection10.2 The muscular system makes movement possible

10.3 Muscles exert forces10.4 Bones and joints at as levers

• Match each definition with the terms.

• 1. a bony structure that allows rotation

• 2. the skeleton division containing the skull

• 3. the part of a bone that produces red blood cells

a. compact bone d. ball-and-socket joint

b. axial skeleton e. marrow

c. immovable joint

db

e

Muscles perform important functions

• Beating heart, moving food through your digestive system, blinking eyes

• Some movements are automatic, some you control

• Muscles help • Produce movement• regulate your body’s temperature (keep it

stable)• maintain your body’s posture

Movement

• Muscular system – consists of skeletal muscles (attached to the skeleton)• Most skeletal muscles are attached to

bones by tendons• Made of muscle fibers (many muscle

cells)• Contract – shorten / relax – lengthen

• Most muscles work in coordinate groups• Bend arm and release: biceps/triceps

coordination

Maintaining Body Temperature

• Homeostasis: the balance of conditions in the body

• A muscle contracts releases heat• Shiver: quick muscle contractions release heat

to warm your body

Maintaining Posture

• Gravity is pulling your body down, but most muscles are always a little bit contracted• Called tension, or muscle tone • This is present even when sleeping!

• Muscles make contracting and relaxing adjustments to keep you sitting or standing• These are automatic

Types of Muscles• All contract and relax

• Perform different functions

• Skeletal• attached to the skeleton• under voluntary control.

• Smooth• located in walls of some organs• under involuntary control

• Cardiac• located in the walls of the heart• under involuntary control

Skeletal Muscles

• Attached to bones

• Help give the body its shape

• Voluntary/controlled movement ~ “voluntary muscles”

• Long fibers made of many bundles made of many cells• Cells can have more than one nucleus

• Slow twitch – move slow but can sustain tension for longer periods

• Fast twitch – move quick but can only sustain tension for shorter periods

Smooth Muscles

• Involuntary muscle

• Contracts slowly

• Walls of stomach and intestines• helps push food through the digestive system

• Also found in blood vessels• helps regulate blood pressure

Cardiac Muscles

• Involuntary muscle

• Only found in the heart

• Each cardiac muscle cell is branched• cells connect in a chain• The chains form webs and layers that allow

cardiac muscle cells to contract together and make the heart beat

Checking in…• What do the bundles that make up skeletal muscle do?

• One type allows muscles to move slowly and maintain tension for a long time. Another allows muscles to move more quickly and sustain tension for a shorter period.

• Why are skeletal muscles called voluntary muscles?

• They move when you want them to.

• Compare and contrast the three types of muscle: skeletal, smooth, and cardiac.

• Skeletal muscles give the body shape and control movement. They are voluntary muscles. Smooth muscles contract without voluntary control. They are found in the walls of the stomach, intestines, and blood vessels. Cardiac muscle moves without conscious control and is found only in the heart.

Skeletal muscles, tendons, and joints allow

bones to move• Many skeletal muscles are

attached to your bones by tendons• Tendons: strong connective

tissue

• Muscle contracts and shorten pull the tendon tendons pulls on the bone to make it move

Muscles can only contract orrelax. By contracting, they pull on the tendons.

How do muscles move bones?

Movement

• Muscles must work together in coordinated groups• Muscle groups produce

movement in opposite directions

• A muscle contracts and shortens – it exerts a force• Counterpart relaxes

• Which muscles work together to bend and extend your leg?

Movement

• Lift your leg without bending your knee

• Which muscles must contract in order to keep your knee from bending?

• What if you point your toes?

• Some of the muscles in your leg are working to stabilize the joints

• Other muscles are contracting to produce the controlled movementMuscular system + skeletal system +

BRAIN!

Muscles grow and heal

• Baby neck muscles not strong enough to hold up head

• Childhood/adolescence: develop muscular coordination and become more graceful in their movements

• Exercise: muscles may get big • # muscle fibers does NOT increase• thickness of the muscle fibers and surrounding tissues

increases

• Muscles can become sore during or after exercise:• During exercise the muscle cells may not receive

enough oxygen for cellular respiration switch to fermentation for energy

• Fermentation causes the buildup of lactic acid in muscles• cramps or aches

• Muscles can also be damaged (overstretched or torn)