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Chapter 3
The Human Body
The Human Body
• First aider must be familiar with the
basic structure and functions of the
human body.
• By using proper terms, you will be
able to better communicate with
medical care providers.
The Respiratory System (1 of 2)
• Death will result in about 4 to 6
minutes unless the oxygen intake is
restored.
• Oxygen is made available to the
blood through the respiratory
system.
The Respiratory System (2 of 2)
• Nose
• Pharynx and
trachea
• Lungs
Mechanics of Breathing
• Respiration
• Passage of air into and
out of the lungs
• Inhalation
• Breathing in
• Exhalation
• Breathing out
Infants and Children
• Infants and children differ from adults.
• Respiratory structures are smaller
and more easily obstructed.
• Tongues take up more space in the
mouth.
• Trachea is more flexible.
The Circulatory System
• Blood
• Heart
• Blood vessels
Heart
• Pumps blood
through blood
vessels
• Powerful, hollow,
muscular organ
as big as a fist
Blood Vessels (1 of 3)
• Arteries
• Elastic, muscular tubes that carry
blood away from the heart
• Begin at the heart as two large
tubes
• Pulmonary artery
• Aorta
• Divides into capillaries
Blood Vessels (2 of 3)
• Pulse
• Surge of blood that occurs each
time the heart contracts
• Can be felt at any point where an
artery lies close to the surface of
the body
• Major locations include: carotid,
femoral, radial, brachial, posterior
tibial, dorsalis pedis arteries
Blood Vessels (3 of 3)
• Blood pressure
• Measures of the pressure exerted
by the blood on the walls of the
flexible arteries
• Might be high or low according to
the resistance offered by the walls
to the passage of blood
Blood
• Plasma
• Liquid part of the blood
• Carries food materials and
waste materials
• Platelets
• Essential for the formation of
blood clots
The Nervous System
• A complex collection of nerve cells that
coordinate the work of all parts of the
human body
• Keeps the individual in touch with the
outside world
• Neurons receive stimuli from the
environment and transmit impulses to
nerve centers in the brain and spinal
cord.
Central Nervous System (1 of 2)
• Brain
• Headquarters of the
human nervous
system
• Divided into the
cerebrum,
cerebellum, and
brain stem
Central Nervous System (2 of 2)
• Spinal cord
• Soft column of nerve
tissue continuous with
the lower part of the
brain
• Enclosed in the bony
vertebral column
• Vulnerable to injury
• Damage is almost
always irreversible
Peripheral Nervous System
• Consists of the sensory and motor
nerves
• Carry sensations such as smell,
touch, heat, and sound from the
body to the brain and the spinal cord
Autonomic Nervous System
• Consists of a group of nerves that
control heart rate, digestion,
sweating, and other automatic body
processes
• Processes are not controlled by the
conscious mind
The Skeletal System
• The human body is
shaped by its bony
framework
• Adult skeleton has
206 bones
• Bones are living
cells surrounded by
hard deposits of
calcium
Skull
• Rests at the
top of the
spinal column
• Contains the
brain
• Can be
fractured by a
blow
Spinal Column
• Made up of
vertebrae
• Bound together by
ligaments
• Intervertebral disks
between every two
vertebrae
Thorax
• Also known as the rib cage
• Made up of ribs and the sternum
• Lowest portion of the sternum is the
xiphoid process
Pelvis
• Two hipbones and the sacrum
form the pelvis
• Muscles help attach the pelvic
bones, the trunk, the thighs, and
the legs
• Forms the floor of the abdominal
cavity
Leg Bones
• Upper leg (thigh)
• Femur
• Knee
• Lower leg
• Tibia
• Ankles, feet, and
toes
Shoulder
• Formed by the collar bone
(clavicle) and the shoulder blade
(scapula)
• Fractures are common
Arm Bones
• Upper arm
• Humerus
• Forearm
Wrist and Hand
• Palm of the hand
has five long bones
• Metacarpals
• 14 bones of the
fingers give hand
flexibility
• Phalanges
Joint
• Where two or more bones meet
or join
• Layer of cartilage acts as a
buffer
• Bones of the joint are held in
place by ligaments
The Muscular System
• Skeletal Muscles
• Smooth Muscles
• Cardiac Muscles
The Skin
• Epidermis
• Outer layer
• Dermis
• Inner layer