1. Chapter 3
The Human Body

2. The Human Body
First aiders must be familiar with the basic structure and functions of the human body.
The most important and sensitive organs include:
Lungs
Heart
Brain
Spinal cord

3. The Respiratory System (1 of 2)
Death will result in about 4 to 6 minutes if the body’s oxygen supply is cut.
Oxygen from air is made available to the blood through the respiratory system.

4. The Respiratory System (2 of 2)

5. Respiration The Passage of Air Into and Out of the Lungs
Mechanics of breathing:
Inhalation is breathing in.
Exhalation is breathing out.
Ventilation is a mechanical process that alternately increases and decreases the size of the chest cavity.

6. Respiratory Information Infants and Children
Respiratory structures are smaller.
Easily obstructed airways
Tongues take up more space in the mouth.
Trachea is more flexible.
Primary cause of cardiac arrest is an uncorrected respiratory problem.

7. Respiratory Rates Decreases at rest Increases during exercise
Controlled by the brain

8. Signs of Inadequate Breathing
A rate outside the normal range
Cool or clammy skin that is pale or cyanotic
Nasal flaring

9. Respiration When Hard Muscular Work Is Performed
Lungs cannot get rid of carbon dioxide.
Lungs cannot take in oxygen fast enough at the normal rate.
As carbon dioxide increases, respiration increases.
Heart rate increases.

10. The Circulatory System (1 of 2)
Blood
Heart
Blood vessels

11. The Circulatory System (2 of 2)
Blood carries nutrients and other products from the digestive tract.
Blood carries oxygen from the lungs.
Blood transports wastes.

12. Heart (1 of 4) Pumps blood through the vessels
A powerful, hollow, muscular organ
About the size of a man’s clenched fist
Shaped like a pear
Located in the left center of the chest

13. Heart (2 of 4)
Divided by a wall to create the right and left compartments
Compartments are divided into two chambers:
Atrium above
Ventricle below

14. Heart (3 of 4) During each contraction:
The heart pumps blood high in carbon dioxide and low in oxygen from the right ventricle to the lungs.
Oxygen-rich blood is returned to the left atrium of the heart from the lungs.

15. Heart (4 of 4)
Left ventricle pushes oxygen-rich blood to the rest of the body.
Right atrium receives oxygen-poor blood.

16. Blood Vessels (1 of 4) 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

17. Blood Vessels (2 of 4) 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.

18. Blood Vessels (3 of 4) 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.

19. Blood Vessels (4 of 4)

20. 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.

21. Locations for Feeling Pulses
Carotid artery
Femoral artery
Radial artery
Brachial artery
Posterior tibial artery
Dorsalis pedis artery

22. Blood Pressure
Blood pressure is a measure of the pressure exerted by the blood on the walls of the flexible arteries.

23. Blood Liquid portion Solid portion Plasma Red blood cells
90% water
Carries food materials
Carries waste materials
Solid portion
Red blood cells
Give blood its color
Carry oxygen
White blood cells
Defense against infection
Platelets
Essential for blood clot formation

24. Hypoperfusion (Shock)
Inadequate circulation of blood through an organ
Signs and symptoms include:
Pale or cyanotic, cool, clammy skin
Rapid pulse
Rapid breathing
Restlessness, anxiety, or mental dullness
Nausea and vomiting
Reduction in total blood volume
Low or decreasing blood pressure
Subnormal body temperature

25. The Nervous System
The nervous system is a complex collection of nerve cells (neurons) that coordinate the work of all parts of the human body and keep the individual in touch with the outside world.

26. Neurons Receive stimuli Transmit impulses Produce nerve impulses
Cannot be regenerated

27. Central Nervous System The Brain (1 of 5)
Headquarters of the human nervous system
Most highly specialized organ
Requires considerable oxygen
Three main subdivisions
Cerebrum
Cerebellum
Brain stem

28. Central Nervous System The Brain (2 of 5)
Cerebrum
Divided into two hemispheres
Controls functions such as sensation, thought, and associative memory
The occipital lobe is the sight center.
The temporal lobes direct smell and hearing.

29. Central Nervous System The Brain (3 of 5)
Cerebellum
Located at the back of the cranium, skull, below the cerebrum
Coordinates muscular activity and balance

30. Central Nervous System The Brain (4 of 5)
Brain stem
Extends from the base of the cerebrum to the foramen magnum
Controls breathing and heart rate

31. Central Nervous System The Brain (5 of 5)
Cerebrospinal fluid
Similar to blood plasma
Circulates throughout the brain and spinal cord
Serves as a protective cushion
Exchanges food and waste materials

32. Central Nervous System Spinal Cord (1 of 2)
Soft column of nerve tissue
Exits the brain through the foramen magnum
Thirty-one pairs of spinal nerves branch from the spinal cord

33. Central Nervous System Spinal Cord (2 of 2)
Some fibers carry impulses in, others carry impulses away.
Spinal nerves at different levels regulate activities of various parts of the body.
Vulnerable to injury
Damage is usually irreversible.
Injury can cause paralysis.

34. Peripheral Nervous System
Made up of nerves that exit the spinal cord through an opening in the bony canal
Consists of the sensory and motor nerves
If a nerve is seriously damaged, the body part will not work.

35. Autonomic Nervous System
Controls:
Heart rate
Digestion
Sweating
Other automatic body processes

36. The Skeletal System Adult skeleton has 206 bones.
Bones are made of living cells surrounded by hard deposits of calcium.

37. Skull (1 of 3) 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

38. Skull (2 of 3)
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.

39. Skull (3 of 3)

40. Spinal Column (1 of 2)
Consists of irregularly shaped bones called vertebrae
Lie on top of each other to form a strong, flexible column
Bound together by ligaments
Can be damaged by disease or injury

41. Spinal Column (2 of 2)
Careless handling of an injured person can further injure the cord and possibly the person.
A person with a back or neck injury must be handled with extreme care.

42. Thorax Also known as the rib cage Made up of ribs and the sternum
Injuries to the thorax can puncture the lungs and heart.
Lowest portion of the sternum is the xiphoid process.

43. 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

44. Leg Bones (1 of 3)
Upper leg (thigh)
Femur
Knee
Knee joint
Patella

45. Leg Bones (2 of 3)
Lower leg
Tibia
Fibula

46. Leg Bones (3 of 3)
Ankles, feet, and toes

47. Shoulder Shoulder girdle Fractures are common. Collarbone (clavicle)
Shoulder blade (scapula)
Fractures are common.

48. Arm Bones (1 of 2) Upper arm Forearm Humerus Ulna Radius
Easily dislocated
Forearm
Ulna
Radius

49. Arm Bones (2 of 2) Wrist, hand, and fingers
Composed of eight bones (carpals)
Tendons from forearm to fingers
The palm has five long bones (metacarpals).
Fourteen bones of the fingers (phalanges)
The thumb is the most important digit.

50. Joints Where two or more bones meet or join
Some allow little movement, others allow a wide range.
Layer of cartilage acts as a buffer.
Ligaments hold the bones and act as bands of flexible connective tissue.
Enclosed in a capsule
A thick fluid lubricates and protects the joint.

51. The Muscular System (1 of 2)
Voluntary muscles
Under control of the person
Make all deliberate acts possible
Called skeletal muscles
Can be injured in many ways

52. The Muscular System (2 of 2)
Smooth muscles
Very little control by the person
Line the walls of tubelike structures
Cardiac muscle
Found only in the heart
Needs continuous oxygen and glucose

53. The Skin (1 of 2) Covers entire body
Protects deep tissues from being injured, drying out, or being invaded by bacteria and other foreign bodies
Regulates body temperature

54. The Skin (2 of 2) Epidermis (outer layer) Dermis (inner layer)
Varies in thickness
Dead cells are constantly worn off.
Dermis (inner layer)
Rich supply of blood vessels and nerve endings
Contains sweat glands and oil glands
Above the subcutaneous layer