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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