Bones, Muscles and Skin
CHAPTER 8
Section 1
Body
Organization
and
Homeostasis
Body Organization and
Homeostasis
 The levels or organization in the human body
consist of cells, tissues, organs and organ
systems
 Cells is the most basic organized part of the
body
 System is the most advanced
Cells
 Cell is the basic unit of structure and function
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in a living thing
Human body contains about 100 trillion cells
Cell membrane forms on the boundary of the
cell
The nucleus is the control center that directs
the cells activities
The material within a cell is the cytoplasm, it
is clear and jelly-like
Cells
 Inside the cytoplasm are structures called
organelles
 Cells carry on the processes that keep the
organism alive
 Cells grow and reproduce
 They rid the organism of waste and helps
break down food to release energy
Tissues
 Tissue is a group of similar cells that perform
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the same function
Muscular tissue can shorten and contract
Nervous tissue directs and controls the body
using electrical messages
Connective tissue provides support and
connects all its parts
Epithelial tissue covers you body inside and
out
Organ and Organ Systems
 Organ is a structure that is composed of
different kinds of tissue
 Organs perform a specific job like a tissue,
but is more complex than a tissue
 An organ system is a group of organs that
work together to perform a major function
Homeostasis
 The different organ systems work together
and depend on one another
 All the systems of the body work together to
maintain homeostasis, to keep the internal
balance
 Homeostasis is the process by which an
organism’s internal environment is kept
stable in spite of changes in the external
environment
Homeostasis
 Very simply even when its cold out, your body
will always have the same temp.
 Body temp. will drop when you are sick
 Your body has various ways to maintain
homeostasis
 When it is warm out, you sweat to help cool off
your body
 When it is cold, your body shivers, the shivering
helps to provide heat for your body
Section 2
The Skeletal
System
What the Skeletal System
Does
 Our skeleton is our framework
 It is made up of all the bones in our body
 The number of bones in your body depends
on how old you are.
 A newborn has 275 bones
 An adult has 206 bones
 As babies grow, bones in the body fuse together.
What the Skeletal System
Does
 Your skeleton has 5 major functions
 Provides support and shape for the body
 Enables you to move
 Protects your organs
 Produces blood cells
 Stores minerals and other materials until your
body needs them
What the Skeletal System
Does
 The backbone, or vertebral column , is the
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center of the skeleton.
If you run your fingers down the length of
your back you will feel 26 vertebrae
Most of the bones in your body are
associated with muscles
Bones also protect vital organs
Bones also produce certain blood cells, and
store other vitamins and minerals.
Joints of the Skeleton
 A joint is a place in the body where 2 bones
come together
 Joints allow bones to move in different ways
 There are 2 different types of joints,
moveable and immoveable.
 Immovable are joints that allow for little or no
movement
 The bones in the skull are held together by
immovable joints
Joints of the Skeleton
 Most of the joints in the body are moveable
joints.
 Moveable joints allow for a wide range of
motion
 The joints in the body are held together by
strong connective tissues called ligaments
 Most joints have a second connective tissue
called cartilage, which is more flexible than
bone
Joints of the Skeleton
 Cartilage covers the ends of the bones and
keeps them from rubbing together
 There is also a fluid that helps to lubricate the
ends of the bones
Bones- Strong and Living
 The word skeleton comes from a Greek word
meaning “a dried body”
 Bones are actually complex living structures
that undergo growth and development
 The longest bone in your body is your Femur,
it is also the toughest to break.
 Blood vessels and nerves enter and leave the
bone through the membrane.
Bones- Strong and Living
 Beneath the bone’s outer membrane is a
layer of compact bone, which is hard and
dense, but not solid.
 These small canals carry blood vessels and
nerves from the bone’s surface to the living
cells within bone.
 Spongy bone has many small spaces within it
 This structure makes spongy bone tissue
lightweight.
Bones- Strong and Living
 Inside many bones contain a soft, connective
tissue called marrow.
 There are 2 types of marrow, red and yellow
 Red bone marrow produces most of the body’s red
blood cells.
 As a child most of your marrow is red, as a
teenager, only the ends of femurs, skull, hip
bones, and sternum
 Yellow marrow stores fat as an energy reserve
Bones- Strong and Living
 Bones are strong and lightweight, stronger
than concrete or granite rock.
 Only 20% of an adults weight is bone
 Even when you get old, your bone tissue will
continue to grow
 So even when you break a bone, new bone
tissue forms and the healed region will be
stronger than before.
 Bones develop from cartilage into bone, but
not everywhere
Taking Care of Your Bones
 A combination of a balanced diet and regular
exercise are important for a lifetime of
healthy bones
 A healthy diet has calcium and phosphorus
 Meats, whole grains, leafy vegetables, and dairy
products.
 We try to prevent against osteoporosis
 Condition in which the body’s bones become
weak and break easy.
Section 3
Diagnosing
Bone and Joint
Injuries
Common Skeletal System
Injuries
 3 common skeletal system injuries are
fractures, dislocations, and sprains.
 A fracture is a break in the bone.
 Simple=> cracked or completely broken in 2 or
more pieces.
 Compound=> the bone is sticking out of the skin
 Dislocation occurs when the end of a bone
comes out of its socket
 Sprain is when ligaments stretch to far
Identifying Injuries
 There are 2 ways to identify injuries of the
skeletal system, X-rays and MRI
 X-rays are a form of energy that travels in
waves
 A lead apron is used to protect from unnecessary
exposure
 The X-rays pass thru soft tissue but not the
bones
 One limitation is that it can not be used to observe
soft tissue damage
Identifying Injuries
 An MRI, magnetic resonance imaging, is a
large machine that contains magnets
 The subject is exposed to short bursts of
magnetic energy
 This causes atoms in the body to vibrate or
resonate.
 A computer then analyzes the vibration patterns.
Treating Injuries
 In addition to wearing a cast, 2 other ways to
treat skeletal system injuries include surgical
procedures such as joint replacement and
arthroscopy
 Joint replacement usually happens to people
with arthritis, a disease of the joints.
Treating Injuries
 Arthroscopic surgery
 Doctors make a small incision and insert a slim,
tube shaped instrument called an arthroscope.
 Attached to the arthroscope is a small camera
that is connected to a small monitor.
 Once the problem area is found, doctors make
another incision and use small instruments to
make necessary repairs.
Section 4
The
Muscular
System
Types of Muscles
 There are about 600 muscles in the human
body.
 Some muscles are easy to control, others are
impossible to control
 The beating of your heart and breathing are
muscles you are unable to control, these are
called involuntary muscles.
Types of Muscle
 There are 3 types of muscle tissue
 Skeletal muscle
 Smooth muscle
 Cardiac Muscle
 Some are voluntary, some are involuntary
Types of Muscles
 Skeletal muscles are attached to the bones of
your skeleton and provide the force that moves
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your bones
Skeletal muscle is striated, meaning its in badns
and gets tired
At the end of a skeletal muscle is a tendon
A tendon is a strong connective tissue that
attaches muscle to bone
Because you are able to control the muscles in
your arms and legs, they are a voluntary muscle
Types of Muscles
 Smooth muscle are inside many internal
organs such as the stomach and blood
vessels.
 Since you can not control your stomach,
these muscles are involuntary
 Smooth muscles tire more slowly than
skeletal muscle
Types of Muscle
 Cardiac muscle is found only in your heart
 Cardiac muscle has some characteristics with
both smooth and skeletal muscle
 Cardiac muscle never gets tired like skeletal
muscle, but is striated.
 It is also involuntary
Muscles at Work
 Because muscle cells can only contract, not
extend, skeletal muscles must work in pairs.
 While one muscle contracts, the other muscle
in the pair relaxes to its original length.
Section 5
The Skin
The Body’s Tough Covering
 The skin protects the body from injury,
infection, and water loss.
 The skin also helps regulate body
temperature, eliminate wastes, gather info.
About the envir., and produce vitamin D.
The Epidermis
 The skin is organized into 2 main layers, the
epidermis and dermis.
 The epidermis is the outer layer of the skin
 Epidermis is usually thinner than the dermis
 The epidermis does not have any blood vessel
or nerves
 This is why shallow scratches do not bleed or hurt
The Epidermis
 Epidermal cells have a life cycle
 The skin cells we see, and come off as dead
skin cells, were once living when at the
bottom of the epidermal layer
The Epidermis
 In some ways, the cells of the epidermis are
more valuable dead than alive.
 Most protection is due to the layer of dead
cells on the surface
 Shedding of dead skin cells carries away
bacteria and other substances on your skin.
 Skin also produces melanin, a pigment, or
colored substance that gives skin its color
The Dermis
 The dermis is the inner layer of the skin.
 The dermis is about a layer of fat but beneath
the epidermal layer.
 The fat layer helps to pad the internal organs
and helps keep heat in the body.
 The dermis is the layer of skin that has
nerves, blood cells, sweat glands, hairs and oil
glands.
The Dermis
 Sweat glands produce perspiration which
reach the surface through pores.
 Strands of hair grow within the dermis in
structures called follicles
 The hair you see about the epidermal layer is
made up of dead cells
Caring for your Skin
 3 simple habits can help you keep your skin
healthy
 Eat a healthy diet
 Keep your skin clean and dry
 Limit your exposure to the sun
The End