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An Introduction to the
Body Systems
The Human Body Plan
Skeletal System
Muscular System
Integumentary System
Objectives
• Describe four types of tissues that make up the
human body.
• Explain how tissues, organs, and organ
systems are organized.
• Summarize the functions of the primary organ
systems in the human body.
• Identify the five human body cavities and the
organs that each contains.
Levels of Structural
Organization
Chemical – atoms combine to form molecules
Cellular – molecules interact to make up cells
Tissue – cells are grouped into tissue
Organ – tissues compose organs
Organ system – organs function together to
form organ systems
Organism (individual) – made up of the organ
systems
Body Tissue
•
All tissues are a collection of cells
that have a similar structure and that
work together to perform a particular
function.
•
Four types of body tissue:
1.
2.
3.
4.
Muscle tissue
Nervous Tissue
Epithelial Tissue
Connective Tissue
1. Muscle
Tissue
– composed of cells that can contract
in a coordinated fashion.
– The human body has three types of
muscle tissue: skeletal, smooth, and
cardiac.
• Skeletal muscle moves the bones
in your trunk, limbs, and face.
• Smooth muscle handles body
functions that you cannot control
consciously.
• Cardiac muscle, found in your
heart, pumps blood through your
body.
Chapter 45
Body Tissues, continued
2. Nervous Tissue
– Nervous tissue
contains cells,
or neurons, that
receive and
transmit messages
in the form of
electrical impulses.
– Neurons are nerve cells that are
specialized to receive and send electrical
impulses
Chapter 45
Nervous Tissue, continued
– Nervous tissue can be found throughout
the human body and has various
functions.
• For example, nervous tissue can be found in
the brain and sensory organs and is used to
interpret sensory information.
Chapter 45
Body Tissues, continued
3. Epithelial Tissue- tissue that is
composed of a sheet of cells and that
covers a body surface or lines a body
cavity.
– Epithelial tissue is found in various
thicknesses and arrangements, depending
on where it is located.
Chapter 45
Body Tissues, continued
• Epithelial Tissue, continued
– Each epithelial layer
is formed from cells
that are tightly bound
together, often
providing a protective
barrier for these
surfaces.
Chapter 45
Body Tissues, continued
4. Connective Tissue
is a tissue that has
a lot of intracellular
substance and that
connects and
supports other
tissues.
Chapter 45
Body Tissues, continued
• Connective Tissue, continued
– Connective tissues are the most
abundant and diverse of the four types
of tissue and contain a substance called
matrix.
– Matrix is an intracellular substance that
gives connective tissue its strength and
flexibility and can be solid, semisolid, or
liquid.
Chapter 45
Human Body Tissues
Chapter 45
Organs and Organ Systems
• An organ consists of various tissues
that work together to carry out a
specific function.
• Groups of organs interact in an organ
system.
• Organ systems work together to
function in an efficient, integrated
manner.
Organs and Organ Systems
• Integration of Organ Systems
– An even higher level of organization is the
integration of organ systems.
– The integration of organ systems can be
described as each organ system having
organs associated with it according to that
organ’s primary function. This is so the
organ system can work more efficiently.
Body Cavities
• Many organs and organ systems in the
human body are housed in compartments
called body cavities.
• These cavities protect internal organs from
injuries and permit organs to function while
remaining securely supported.
• Each human cavity can contains one or more
organs.
Body Cavities continued…
– The human body has five main body
cavities, including the cranial cavity, the
spinal cavity, the thoracic cavity, the
abdominal cavity, and the pelvic cavity.
– The cranial cavity is the cavity that
contains, supports, and protects the brain.
– The spinal cavity is the cavity that
contains, supports, and protects the spinal
cord.
Body Cavities continued…
• The thoracic cavity is the cavity that contains,
supports, and protects the heart, esophagus, and the
organs of the respiratory system.
• The abdominal cavity is the cavity that contains,
supports, and protects the digestive system.
• The pelvic cavity is the cavity that contains,
supports, and protects the organs of the
reproductive and excretory systems
Objectives:
Skeletal System
• Distinguish between the axial skeleton and
the appendicular skeleton.
• Explain the function and structure of bones.
• Summarize how bones develop and
elongate.
• List three types of joints and give an example
of each.
• Describe a common disorder that affects the
skeleton
The Skeletal System
• Composed of bone, cartilage, and
ligaments
• Protects and supports body organs
• Provides the framework for muscles
• Site of blood cell formation
• Stores minerals
The Skeleton
• A skeleton is the bones of a human or
animal body that form the framework of
the body, support the muscles and
organs, and protect the inner organs.
• The variation in size and shape among
the bones that make up the skeleton
reflects their different roles in the body.
Subsections of the
Human Skeleton
o The purple is the axial
skeleton and the yellow is
the appendicular skeleton.
The Skeleton Is Divided Into
Two Distinct Parts:
1. The axial skeleton
consists of bones
that form the axis of
the body and
support and protect
the organs of the
head, neck, and
trunk.
• Click on these links to
read about the axial
parts of the body.
• The skull
• The sternum
• The ribs
• The backbone
The Appendicular Skeleton
2. The appendicular
skeleton is
composed of bones
that anchor the
appendages to the
axial skeleton.
• Click on these links to
read about the
appendicular parts of
the body.
• The lower body
• The upper body
• The shoulders
• The pelvic area
• Axial skeleton
– skull (cranium and facial bones)
– hyoid bone (anchors tongue and muscles
associated with swallowing
– vertebral column (vertebrae and disks)
– thoracic cage (ribs and sternum)
• Appendicular skeleton
– pectoral girdle (clavicles and scapulae)
– upper limbs (arms)
– pelvic girdle (coxal bones, sacrum, coccyx)
– lower limbs (legs)
Bone Function and Structure
• The bones that make up the skeleton function
in a variety of ways
–
–
–
–
support muscles
protect internal organs
help movement
play vital roles in important metabolic processes.
• Bones do not make up most of a body’s
mass.
– Being “big boned” is no excuse for being
overweight!
Types of Bones
The bones of the body fall into four general categories:
1. Long bones are longer than they are wide and work
as levers. The bones of the upper and lower
extremities are of this type.
2. Short bones are short, cube-shaped, and found in
the wrists and ankles.
3. Flat bones have broad surfaces for protection of
organs and attachment of muscles
4. Irregular bones are all others that do not fall into the
previous categories. They have varied shapes,
sizes, and surfaces features and include the bones
of the vertebrae and a few in the skull.
Bone Function and Structure
• Long Bone Structure
– A long bone’s surface is covered by a
tough membrane called the periosteum.
– Periosteum is a white, double layered
membrane that covers the entire surface
of bone except for the joint surfaces and is
richly supplied with nerve fibers and blood
vessels.
Long Bone Structure, continued
• Under the periosteum is a hard material
called compact bone, and this part of the
bone gives all bones their strength and
rigidity.
• Compact bone is composed of cylinders
made of mineral crystals and protein fibers.
• Beneath some compact bone is a network of
connective tissue called spongy bone.
• Spongy bone is less dense bone tissue that
has many open spaces.
Bone Function and Structure
continued…
• Bone marrow is a soft tissue inside
some bones that can be either red or
yellow.
– The type of bone marrow present
determines both its composition and
function.
Bone Function and Structure
continued…
• Injury and Repair
– Despite their strength, bones will crack or
even break if they are subjected to certain
situations or are overused.
– A crack or break is referred to as a
fracture.
• A fracture is an injury in which the
tissue of a bone is broken.
Bone Development
• During fetal development, some bones
that were originally cartilage will slowly
be replaced by actual bone. This
process is called ossification.
• Humans are born with over 300 bones,
but adults have about 206 bones.
Where are the 206 Bones?
•
•
•
•
•
22 bones in skull
6 in middle ears
1 hyoid bone
26 in vertebral column
25 in thoracic cage
•
•
•
•
4 in pectoral girdle
60 in upper limbs
60 in lower limbs
2 in pelvic girdle
Bone Development
• Bone Elongation
– Bones continue to grow after a person’s
birth.
– Bone elongation and growth take place
near the ends of long bones in an area
known as the epiphyseal plate.
• The epiphyseal plate is found at the joint ends
of long bones and is composed of cartilage.
This area of bone will eventually become
mature bone.
Joints
• The place where two bones meet is
known as a joint
• Three major kinds of joints are found in
the human body
– Fixed
– Semimovable
– Movable
Types of Joints
• Fixed Joints
– A joint at which no movement occurs
• Semimovable Joints
– A joint that will permit limited movement
– Cartilage can be involved to help these
joints move.
• Movable joint
- A joint at which a wide range of motion
occurs.
– There are different types of movable joints,
including hinge, ball-and-socket, pivot,
saddle, and gliding.
Movable Joints
– A hinge joint allows limited movement in only one
plane.
– A ball-and-socket joint is another type of
moveable joint and allows 360 degree movement
in 2 planes.
– A pivot joint allows 180 degree movement in only
one plane.
– A saddle joint will allow 360 degree movement in
only one plane.
– A gliding joint allows bones to slide over one
another.
Gliding Joint
Joint Structure
– Joint structure helps movable joints deal
with the pressure and stress of everyday
life.
– Joints are covered with cartilage and
secrete synovial fluid to reduce friction.
Joints are also connected with ligaments
(hold bone to bone) and tendons (hold
muscle to bone) to aid in joint movement.
– Even with all this protection a joint can still
be injured.
Joints continued…
– The term arthritis is used to describe
disorders that cause painful, swollen
joints.
• Rheumatoid arthritis develops when the
immune system begins to attack body tissues,
and joints become stiff and deformed.
• Osteoarthritis is a degenerative joint disease in
which the cartilage covering the surface of
bone becomes thinner and rougher.
Other Links
• *Site of Anatomy
Terms
• *Listen to audio
recordings about the
skeletal system
• *Click on any part of
the skeleton and it will
tell you about that
part of the body
Objectives:
Muscular System
• Distinguish between the three types
of muscle tissues.
• Describe the structure of skeletal
muscle fibers.
• Explain how skeletal muscles
contract.
• Describe how muscles move bones.
• Explain the process in which a muscle
becomes fatigued.
Muscular system
• Composed of
muscles and
tendons
• Allows
manipulation of
the environment,
locomotion, and
facial expression
• Maintains
posture
• Produces heat
Muscle Types
• A muscle is an organ that can contract in a
coordinated fashion and includes muscle tissue,
blood vessels, nerves, and connective tissue.
• Their ability to contract and relax not only
enables the body to move, but also provides the
force that pushes substances, such as blood
and food, through the body.
• The human body has three types of muscle
tissues: skeletal, smooth, and cardiac.
Skeletal Muscle
• Skeletal muscles consciously control
the moving parts of the body and are
often referred to as voluntary muscles.
• Skeletal muscles are made up of
muscle fibers.
– Muscle fibers consist of multinucleated
elongated cells with light and dark stripes.
These stripes are called striations.
Skeletal Muscle continued…
• Muscle fibers are grouped into
bundles called fascicles.
• Groups of fascicles are bound
together by connective tissue to
form a muscle.
• The connective tissue in skeletal
muscle cells can unite to form
tendons.
Smooth Muscle
• Smooth muscles are spindle-shaped, have a
single nucleus, and interlace to form sheets.
• Smooth muscle lacks striations, and the
connective tissue that surrounds it cannot
form tendons.
• Smooth muscle forms the walls of the
stomach, intestines, blood vessels, and other
internal organs. Because most of its
movements cannot be consciously
controlled, smooth muscle is
referred to as involuntary muscle.
Cardiac Muscle
• Cardiac muscle makes up the
walls of the heart.
• Cardiac muscle shares some
characteristics with both skeletal
muscle and smooth muscle.
– As with skeletal muscle, cardiac
muscle tissue is striated; as with
smooth muscle, it is involuntary and
each cell has one nucleus.
Muscular Contractions
• Muscle contraction is an all-or-none
response—either the fibers contract or
they remain relaxed.
• The force of a muscle contraction is
determined by the number of muscle
fibers that are stimulated.
– As more fibers are activated, the force of
the contraction increases.
Muscular Movement of Bones
• Muscles are attached to the outer membrane
of bone, the periosteum, either directly or by
a tough fibrous cord of connective tissue
called a tendon.
• The point where the muscle attaches to the
stationary bone is called the origin.
• The point where the muscle attaches to the
moving bone is called the insertion.
Muscular Movement of Bones
• Most skeletal muscles are arranged in
opposing pairs, and muscles move bones by
pulling them.
• The muscle that bends a joint is known as a
flexor.
• A muscle that straightens a joint is known as
an extensor.
• In order for smooth movement, one muscle
in a pair must contract while the opposing
muscle relaxes.
Opposing Muscles in the Arm
Objectives:
Integumentary System
• Describe the functions of the skin.
• Distinguish between the two layers
that form skin.
• Identify two types of glands found in
the skin, and describe their functions.
• Describe the structure of nails.
• Describe the structure of hair.
Layers of Skin:
Epidermis and Dermis
• Epidermis
– Outer layer
– From the Greek epi, meaning “on” or “upon”
and derma meaning “skin”
– Composed of scaly epithelial cells, top layer
mostly dead
– Cells filled with the protein keratin which gives
skin a tough, leathery, waterproof quality
– Skin color determined by the amount of
melanin in the lower layers of the epidermis
Layers of Skin:
Epidermis and Dermis
• Dermis
– The dermis is the inner layer of skin and is
composed of living cells and other specialized
structures such as:
• Sensory neurons, blood vessels, muscle fibers,
hair follicles, and glands
– These specialized cells help the skin protect
the body as much as possible
Glands
– The skin contains
exocrine glands, which
are glands that release
secretions through
ducts.
– The main exocrine
glands present in the
skin are sweat glands
and oil glands.
–
help regulate the bodies temperature.
– Sweat glands are
distributed throughout the
body and release excess
water, salts, and urea.
– Oil glands secret a
substance called sebum.
– Sebum is an oily secretion
that prevents excess water
loss, softens hair and skin,
and protects the body by
being mildly toxic to some
bacteria.
– Acne occurs when the
ducts of oil glands become
clogged with excessive
amounts of sebum, dead
cells, and bacteria.
Cross section of Skin
Hair & Nails
• Nails help protect the
fingers and toes by
forming nail roots under
skin folds at the base and
sides of the nail.
• Nails are also made
primarily of keratin and
rest on a bed of tissue
filled with blood vessels.
• Hair protects and
insulates the body and is
produced by hair follicles,
which are clusters of cells
at the base of deep
dermal pits.
• Hair is composed of
keratin and is kept soft by
the oil glands associated
with the hair follicle.
• Hair color is the result of
the presence of the
pigment melanin in the
hair shaft.