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Chapter 3The Human Body
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.
Directional Terms
• Right and left: the person’s right and left
• Anterior: front of body• Posterior: back of body• Superior: closer to
head• Inferior: closer to feet
© Jones & Bartlett Learning.
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
Directional Terms
• Quadrant: section of the abdominal cavity divided by horizontal and vertical lines intersecting at the umbilicus; four equal areas. © Jones & Bartlett Learning.
The Body Systems
• Most life-threatening conditions affect the respiratory, circulatory, and nervous systems.
• Most important and sensitive organs:− Lungs− Heart− Brain− Spinal cord
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.
The Respiratory System
© Jones & Bartlett Learning.
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.
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.
Respiratory Rates
• Decreases at rest• Increases during
exercise• Controlled by the
brain
© Jones & Bartlett Learning.
Signs of Inadequate Breathing
• A rate outside the normal range• Cool or clammy skin that is pale or
cyanotic• Nasal flaring
The Circulatory System
• Blood• Heart• Blood vessels
© Jones & Bartlett Learning.
Heart
• Pumps blood through the vessels
• About the size of a man’s clenched fist
• Shaped like a pear• Located in the left
center of the chest
© Jones & Bartlett Learning.
Heart
• Divided by a wall to create the right and left compartments
• Compartments are divided into chambers:− Atrium above− Ventricle below
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.
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.
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
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.
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.
Blood Vessels
© Jones & Bartlett Learning.
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.
Locations for Feeling Pulses
• Carotid artery• Femoral artery• Radial artery• Brachial artery• Posterior tibial artery• Dorsalis pedis artery
© Jones & Bartlett Learning.
Blood Pressure
• Blood pressure is a measure of the pressure exerted by the blood on the walls of the flexible arteries.
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
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
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
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
Central Nervous System: The Brain
• Headquarters of the nervous system
• Three main subdivisions− Cerebrum− Cerebellum− Brainstem
© Jones & Bartlett Learning.
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
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
Central Nervous System: Spinal Cord
© Jones & Bartlett Learning.
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
Autonomic Nervous System
• Controls:− Heart rate− Digestion− Sweating− Other automatic body processes
The Skeletal System
• Adult skeleton has 206 bones.
• Bones are made of living cells surrounded by hard deposits of calcium.
© Jones & Bartlett Learning.
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
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.
Skull
© Jones & Bartlett Learning.
Spinal Column
• Consists of irregularly shaped bones called vertebrae− Form a strong, flexible
column− Bound together by
ligaments• Can be damaged by
disease or injury© Jones & Bartlett Learning.
Thorax
• Also known as the rib cage• Made up of ribs and the sternum• Injuries to the thorax can puncture the
lungs and heart.
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
Leg Bones
• Upper leg (thigh)− Femur
• Knee− Knee joint− Patella
© Jones & Bartlett Learning.
Leg Bones
• Lower leg− Tibia− Fibula
© Jones & Bartlett Learning.
Leg Bones
• Ankles• Feet• Toes
© Jones & Bartlett Learning.
Shoulder
• Shoulder girdle− Collarbone (clavicle)− Shoulder blade (scapula)
• Fractures are common.
Arm Bones
• Upper arm− Humerus
• Easily dislocated
• Forearm− Ulna− Radius
© Jones & Bartlett Learning.
Arm Bones
• Wrist, hand, fingers– Composed of eight
bones (carpals)– Five long bones of the
palm (metacarpals)– Fourteen bones of the
fingers (phalanges)– The thumb is the most
important digit.© Jones & Bartlett Learning.
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.
The Muscular System
• Voluntary muscles− Under control of
the person− Called skeletal
muscles− Can be injured in
many ways
© Jones & Bartlett Learning.
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
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.
The Skin
• Dermis (inner layer)− Rich supply of blood vessels and nerve endings− Contains sweat and oil glands
© Jones & Bartlett Learning.