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