2. The Human Body
• First aid providers must be familiar with
the basic structure and functions of the
human body.
• Using the proper medical terms allows you
to communicate more effectively with the
person and with medical care providers.
4. Directional Terms
• Lateral: farther from the middle
• Medial: closer to the middle
• Proximal: close to where the limb is
attached to the body
• Distal: distant from the point of attachment
• Superficial: closer to or on the skin
• Deep: farther inside the body
6. The Body Systems
• Most life-threatening conditions affect the
respiratory, circulatory, and nervous
systems.
• Most important and sensitive organs:
− Lungs
− Heart
− Brain
− Spinal cord
7. The Respiratory System
• Death will result in about 4 to 6 minutes if
the body’s oxygen supply is cut off.
• Oxygen from air is made available to the
blood through the respiratory system.
9. Mechanics of Breathing
• Respiration: The passage of air into and
out of the lungs.
− Inhalation is breathing in.
− Exhalation is breathing out.
• Ventilation: A mechanical process that
alternately increases and decreases the
size of the chest cavity.
10. Mechanics of Breathing
• Infants and children
− Smaller respiratory structures
− Easily obstructed airways
− Tongues take up more space in the mouth.
− More flexible trachea
− Primary cause of cardiac arrest is an
uncorrected respiratory problem.
15. Heart
• Divided by a wall to create the right and
left compartments
• Compartments are divided into chambers:
− Atrium above
− Ventricle below
16. Heart
• During each contraction:
− The heart pumps blood high in carbon dioxide
from the right ventricle to the lungs.
− Oxygen-rich blood is returned to the left
atrium from the lungs.
− Left ventricle pushes oxygen-rich blood to the
rest of the body.
− Right atrium receives oxygen-poor blood.
17. Heart
• At each relaxation:
− Blood flows into the left atrium from the lungs.
− Blood flows into the right atrium from the rest
of the body.
18. Blood Vessels
• Arteries
− Elastic, muscular tubes that carry blood away
from the heart
− Begin at the heart as two large tubes
• Pulmonary artery: Carries blood to the lungs
• Aorta: Carries blood to other parts of the body and
divides into capillaries
19. Blood Vessels
• Capillaries
− A network of extremely fine vessels
− Oxygen and nourishment pass out of the
bloodstream into the body’s cells.
− Cells discharge waste into the bloodstream.
− In the lungs, carbon dioxide is released and
oxygen is absorbed.
20. Blood Vessels
• Veins
− Become larger and larger
− Form major trunks that empty blood returning
from the body into the right atrium
− Blood returning from the lungs goes into the
left atrium.
22. Pulse
• Surge of blood that occurs each time the
heart contracts
• Can be felt at any point where an artery
lies near the skin surface
• Blood from a cut artery spurts.
• Blood from a cut vein flows.
24. Blood Pressure
• Blood pressure is a measure of the
pressure exerted by the blood on the walls
of the flexible arteries.
25. Blood
• Solid portion
– Red blood cells
− Carry oxygen
– White blood cells
− Defense against
infection
– Platelets
− Essential for blood
clot formation
• Liquid portion
– Plasma
− 90% water
− Carries food
materials
− Carries waste
materials
26. Hypoperfusion (Shock)
• Inadequate blood circulation
− Signs and symptoms include:
• Pale or cyanotic, cool, clammy skin
• Rapid pulse and/or breathing
• Restlessness, anxiety, or mental dullness
• Nausea and vomiting
• Reduction in total blood volume
• Low or decreasing blood pressure
• Subnormal body temperature
27. The Nervous System
• A complex collection of nerve cells that
coordinate all parts of the human body
• Neurons
− Receive stimuli
− Transmit impulses
− Produce nerve impulses
− Cannot be regenerated
28. Nervous System Classifications
• Central nervous system (CNS)
− Includes the brain and spinal cord
• Peripheral nervous system
− Network of nerve cells
− Divided into voluntary and autonomic
(involuntary) systems
30. Central Nervous System:
The Brain
• Cerebrospinal fluid
− Similar to blood plasma
− Circulates through the brain and spinal cord
− Serves as a protective cushion
− Exchanges food and waste materials
31. Central Nervous System:
Spinal Cord
• Soft column of nerve tissue
• Continuous with the lower part of the brain
• Enclosed in the bony vertebral column
• Thirty-one pairs of spinal nerves
• Vulnerable to injury
33. Peripheral Nervous System
• Made up of nerves that exit the spinal cord
− Sensory nerves
− Motor nerves
• If a nerve is seriously damaged, the body
part will not work.
• Well protected against injury
34. Autonomic Nervous System
• Controls:
− Heart rate
− Digestion
− Sweating
− Other automatic body processes
36. Skull
• Rests at the top of the spinal column
• Houses the brain, certain glands, and the
centers of special senses
• Two parts
− Brain case (cranium)
− Face
37. Skull
• Blood vessels and nerve trunks pass to
and from the brain through openings in the
skull.
• Can be fractured
• Does not “give”
• The face extends from the eyebrows to the
chin.
40. Thorax
• Also known as the rib cage
• Made up of ribs and the sternum
• Injuries to the thorax can puncture the
lungs and heart.
41. Pelvis
• Formed by two hipbones and the sacrum
• Muscles help connect pelvic bones, trunk,
thighs, and legs.
• Forms the floor of the abdominal cavity
• Holds the bladder, rectum, and internal
parts of the reproductive organs
48. Joints
• Where two or more bones meet or join
• Allow movement
• Layer of cartilage acts as a buffer
• Ligaments hold the bones and act as
bands of flexible connective tissue.
• A thick fluid protects the joint.
50. The Muscular System
• Smooth muscles
− Very little control by the person
− Line the walls of tube-like structures
• Cardiac muscle
− Found only in the heart
− Needs continuous oxygen and glucose
51. The Skin
• Covers entire body
• Protects deep tissues from being injured,
drying out, or being invaded by bacteria
• Helps regulate body temperature
• Epidermis (outer layer)
− Dead cells are constantly worn off.
