Chapter 3 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