1. Chapter 7
General Physiology

2. Skeletal and Muscular Systems
Lesson 7.1
Skeletal and Muscular Systems
Pronounce, define, and spell the Key Terms.
Explain why understanding physiology is important to the dental assistant.
Locate the skeletal system; explain its purpose, components, and functions; and describe the signs and symptoms of its common disorders.
Locate the muscular system; explain its purpose, components, and functions; and describe the signs and symptoms of its common disorders.

3. Introduction Physiology is the study of how living things function
It continues beyond the study of anatomy into how parts work, what they do, and why
What is human anatomy? (Anatomy is the study of the shape and structure of the human body.)
How many body systems does the body have? (10)

4. General Physiology The human body has 10 systems
Each system has specific organs within it
Each body system performs specific functions
In a healthy human being, all 10 systems are functioning
Body systems do not operate independently; they exert important effects on each other. For example, when you exercise hard, your muscular system needs extra oxygen, so your respiratory system works harder than usual to supply it.
The ovaries and testes clearly belong to the reproductive system. However, because one of their functions is to produce hormones, they are also components of the endocrine system.
When something happens in one system, it can often affect another. For example, if your nervous system reacts to upsetting information while you are eating, your digestive system may not function as well as usual.

5. Major Body Systems
The human body has 10 systems: (1) skeletal, (2) muscular, (3) cardiovascular (including the lymphatic and immune systems), (4) nervous, (5) respiratory, (6) digestive, (7) endocrine, (8) urinary, (9) integumentary (skin), and (10) reproductive.

6. Skeletal System There are 206 bones in the human body
For descriptive purposes, the skeleton is divided into the axial and appendicular skeletal systems
The major functions of the skeletal system are protection, support, and shape; hematopoiesis (manufacture of blood cells); and storage of certain minerals.
Remember that “axial” pertains to the body region comprising the head, neck, and trunk and “appendicular” pertains to the arms and legs.

7. Axial Skeleton Consists of the skull, spinal column, ribs, and sternum
Its function is to protect the major organs of the nervous, respiratory, and circulatory systems
The bones of the skull are of primary importance to the dental assistant
What is the skull? (It is the skeletal structure of the head, composed of the facial and cranial bones. The skull houses and protects the brain and most of the chief sense organs—eyes, ears, nose, and tongue. Some 14 bones, most occurring in symmetrical pairs, make up the human face.)
Why is the skull of primary importance to the dental assistant? (The skull is important because that is where the teeth and mouth are located.)

8. The Skeletal System
The skull, spine, and ribcage form the axial skeleton and account for 80 of the 206 bones in the human body.
What are the two divisions of the skeleton? (The two divisions are the appendicular and axial skeletons.)
From Patton KT, Thibodeau GA: Anatomy and physiology, ed 8, St Louis, Mosby, 2013.

9. Appendicular Skeleton
Consists of the upper extremities and shoulder girdle plus the lower extremities and pelvic girdle
It protects the organs of digestion and reproduction
There are many disorders that can affect the skeletal system. See Table 7-2 for more information (p. 60).

10. Bone
Bone is the hard connective tissue that makes up most of the human skeleton
It consists of an organic component (the cells and matrix) and an inorganic (mineral) component
The minerals, mainly calcium and phosphate, give rigidity to bone
These minerals stored in bone also act as a mineral reservoir to maintain essential blood mineral concentrations in times of inadequate supply in the body
Why is it important that we have calcium in the diet when we are growing? (The minerals, primarily calcium and phosphate, give rigidity to bone. These minerals stored in bones also act as reservoirs to maintain essential blood mineral concentrations when the body’s supply is inadequate.)

11. The Structure of Bone
The three layers of bone are (1) periosteum, (2) compact bone, and (3) cancellous bone and bone marrow.
The periosteum is the first layer of bone. A thin layer of whitish connective tissue, it contains nerves and blood vessels.
The periosteum supplies the cells from which the hard bone below the periosteum is built up. It is necessary for bone growth and repair, nutrition, and elimination of waste.
Compact bone, also known as cortical bone, is hard, dense, and very strong. It forms the outer layer of the bones.
Cancellous bone, also known as spongy bone, is found inside the bone.

12. The Periosteum
A specialized connective tissue covering all bones of the body
It is responsible for the life of the bone and is capable of repair
The outer layer is a network of dense connective tissue containing blood vessels
The inner layer is loose connective tissue containing osteoblasts
During dental surgery, care is taken not to traumatize the periosteum of the jaws.
What are osteoblasts? (The cells that produce bone tissue)
How many kinds of bone are found in the body? (2)

13. Kinds of Bone Compact bone Cancellous bone
Hard, dense, and very strong
It forms the outer layer of bone, where it is needed for strength
Cancellous bone
Lighter in weight, but not as strong as compact bone
It is found in the interior of bones
What is osteoporosis? (Osteoporosis, or “porous bone,” is a disease characterized by low bone mass and structural deterioration of bone tissue leading to bone fragility and an increased susceptibility to fractures of the hip, spine, and wrist. Men as well as women suffer from osteoporosis, which can be prevented and treated.)
How are the two types of bone different? (Compact bone is hard, dense, and very strong, while cancellous bone is lighter in weight and not as strong.)

14. Cortical Bone Appears Hard and Dense
Here the mandible is depicted in a periapical radiograph.
Compact bone, also known as cortical bone, is hard, dense, and very strong. It forms the outer layer of the bones (arrows), where it is needed for strength. Cancellous bone, also known as spongy bone, is lighter in weight, but not as strong as compact bone. It is found in the interior of bones.
Where is the cancellous bone on this radiograph? (Answers will vary.)
From Haring JI, Lind LJ: Radiographic interpretation for the dental hygienist, Philadelphia, Saunders, 1993.

15. Trabeculae
Bony spicules in cancellous bone that form a mesh of intercommunicating spaces filled with bone marrow
Appear as a weblike structure on radiographs
What are spicules? (Small pieces of bone)

16. Cancellous Bone Containing Trabeculae
This periapical radiograph shows the alveolar bone.
The trabeculae in cancellous bone appear as a weblike structure on radiographs (arrow).
Where is the compact bone in this radiograph? (Answers may vary.)
From Haring JI, Lind LJ: Radiographic interpretation for the dental hygienist, Philadelphia, Saunders, 1993.

17. Bone Marrow
Inside the spaces of cancellous bone are two types of bone marrow:
Red marrow
Filled with blood vessels
Makes red and white blood cells and platelets
Yellow marrow
Contains mainly fat cells
Found primarily in the shafts of long bones
People are born with only red bone marrow. As a person matures, the red marrow in many of the bones is replaced by yellow marrow. By adulthood, only about half of the bone marrow is red. Red bone marrow is found mostly in the ribs, breastbone, shoulder blades, collarbones, hip bones, skull, and spine.
This means that the elderly are more prone to infections and cancers because the amount of red bone marrow is decreasing and therefore fewer lymphocytes are being produced.

18. Cartilage It is tough, yet more elastic than bone
It is found where bones join together
Nonvascular connective tissue
In addition to the ends of bone, cartilage gives form to the nose and ears
How many types of cartilage are there? (There are three basic forms of cartilage: hyaline cartilage serves as the "type" and the other two forms are described with reference to it. Elastic cartilage and fibrous cartilage are the other two. Many authorities regard fibrous cartilage as a transitional form between cartilage and connective tissue proper.)

19. Joints Areas where two bones come together
There are three basic types of joints
Fibrous: Do not move; example: the sutures of the skull
Cartilaginous: Made of connective tissue and cartilage
An example is the joints between the bones of the vertebrae
Synovial: The movable joints, account for most of the joints in the body
What is arthritis? (Arthritis is a painful condition resulting from inflammation of the joints. Tens of millions of Americans experience chronic or acute pain and physical limitations resulting from the more than 100 forms of arthritis.)
Unlike osteoarthritis, which results from wear and tear on the joints, rheumatoid arthritis is an inflammatory condition. The exact cause is unknown, but it’s believed that the body’s immune system attacks the synovium, the tissue that lines the joints.

20. From Gerdin J: Health careers today, ed 5, St Louis, Mosby, 2012.
Types of Joints
A, Ball-and-socket joint.
B, Hinge joint.
C, Gliding joint.
What are the features of synovial joints? (They consist of two bones whose articular surfaces are covered with hyaline cartilage.)
From Gerdin J: Health careers today, ed 5, St Louis, Mosby, 2012.

21. From Gerdin J: Health careers today, ed 5, St Louis, Mosby, 2012.
Types of Joints
D, Pivot joint.
E, Saddle joint.
The joint space is enclosed by a fibrous capsule. Thickened and organized areas of this capsule make up the named ligaments.
The synovial membrane lines the joint space. This membrane secretes synovial fluid, which fills the joint space and provides lubrication and nourishment to the articular cartilage.
Is the temporomandibular joint a synovial joint? (Yes)
From Gerdin J: Health careers today, ed 5, St Louis, Mosby, 2012.

22. Muscular System
Gives us the ability to stand, walk, run, jump, move our eyes, smile, and frown
It is composed of more than 600 individual muscles
For muscles to make the body move, they must work together
Each muscle consists of muscle tissue, connective tissue, nerve tissue, and vascular (blood) tissue
The major functions of the muscles are locomotion, holding the body erect, movement of body fluids, production of body heat, and communication.
What are the three types of muscle tissue? (Striated, smooth, and cardiac)

23. Muscles of the Body, Anterior View
Muscles are the primary means by which we communicate and interact with the environment.
Speech is dependent on the muscles of the larynx, mouth, and tongue (spoken words); verbal communication can also be accomplished with the muscles of your fingers (written words or sign language).
What other activities are dependent on the skeletal muscles? (Body language, dancing, running, playing, eating, building, or fighting)
From Applegate EJ: The anatomy and physiol­ogy learning system, ed 4, St Louis, 2011, Saunders.

24. Muscles of the Body, Posterior View
Because muscles are so crucial to every animal, they are incredibly sophisticated.
They are efficient at turning fuel into motion, they are long-lasting, they are self-healing, and they are able to grow stronger with practice. They do everything from allowing you to walk to keeping your blood flowing.
From Applegate EJ: The anatomy and physiol­ogy learning system, ed 4, St Louis, 2011, Saunders.

25. Types of Muscles Striated muscle Smooth muscle Cardiac muscle
So named because dark and light bands in the muscle fibers yield a striped, or striated, appearance
Is known as skeletal or voluntary muscle
Attached to the bones of the skeleton; makes bodily motion possible
Smooth muscle
Moves the internal organs, such as the digestive tract, blood vessels, and secretion ducts leading from glands
Cardiac muscle
Striated muscle and smooth muscle produce relatively slow contraction.
Which muscle has striations? (Voluntary, such as the arm or leg muscles)
Which muscle type is attached to the skeleton? (Skeletal muscle)
Which muscles aid digestion and move blood? (Smooth muscle)

26. Smooth Muscle
Involuntary muscle is under the control of the autonomic nervous system and is not controlled voluntarily
Visceral muscle is so named because it is found in the visceral (internal) organs, except the heart
It is also found in hollow structures such as the digestive and urinary tracts
What does voluntary mean in reference to muscle movement? (Voluntary means you are choosing to use the muscles, such as those in the arms and legs.)
Why might one need visceral muscle in the digestive tract? (Answers will vary.)

27. Cardiac Muscle
Striated in appearance but resembles smooth muscle in action
Cardiac muscle forms most of the walls of the heart, and contraction of this muscle results in the heartbeat
It combines the power of striated voluntary muscles with the steady reliability of smooth, involuntary ones
The human heart beats 4 billion times over a lifetime and pumps 600,000 tons of blood.
When does the heart rest? (Between beats)

28. Muscle Function
Contraction is the tightening of a muscle, during which it becomes shorter and thicker
Relaxation occurs when a muscle returns to its original form or shape
The muscles of the body are arranged in opposing pairs so that when one contracts, the other relaxes
It is these contrasting actions that make motion possible
Try contracting a facial muscle, then letting it relax.
What is muscular dystrophy? (A group of rare inherited muscle diseases in which muscle fibers are unusually susceptible to damage and become progressively weaker. In the late stages of muscular dystrophy, fat and connective tissue often replace muscle fibers. In some types of muscular dystrophy, heart muscle, other involuntary muscles, and other organs are affected.)

29. Muscle Function (Cont.)
Muscle origin
The place where the muscle begins (originates)
This is the more fixed attachment, the end of the muscle that is closer to the midline of the body, or both
Muscle insertion
The place where the muscle ends (inserts)
It is the more movable end, the portion of the muscle that is farther from the midline of the body, or both
Where is the midline of the body? (In the middle of the body)
What is the difference between the origin and the insertion of a muscle? (Muscle origin is where the muscle begins, and muscle insertion is where the muscle ends.)

30. Cardiovascular and Nervous Systems
Lesson 7.2
Cardiovascular and Nervous Systems
Locate the cardiovascular system; explain its purpose, components, and functions; and describe the signs and symptoms of its common disorders.
Locate the nervous system; explain its purpose, components, and functions; and describe the signs and symptoms of its common disorders.

31. Cardiovascular System
Consists of the:
Circulatory system
Heart
Lymphatic system
These systems provide life-sustaining capabilities for the survival of body cells and tissues
The main functions of the cardiovascular system are respiratory, nutritive, and excretory.
Studies show a relationship between periodontal disease and cardiovascular disease. People who have cardiovascular disease and periodontal disease are at increased risk because bacterial products can migrate into the pleural cavity and infect the heart.

32. Circulatory System
The two primary functions of the circulatory system are:
Transporting oxygen and nutrients to the cells and transporting carbon dioxide and waste products from the cells, as well as transporting hormones and antibodies throughout the body
Regulating body temperature and chemical stability
What is carbon dioxide? (A colorless, odorless gas, CO2 is a byproduct of respiration. Plants require CO2 for photosynthesis, which generates molecular oxygen.)

33. Heart
Each day the heart pumps 4000 gallons of blood at a speed of 40 mph through 70,000 miles of vessels
The heart is a hollow muscle with four chambers
Heart size varies from individual to individual but is generally the same as a closed fist
See Table 7-4 on p. 66 for disorders of the heart.

34. The Heart and Great Vessels
The right atrium receives blood from the superior and inferior venae cavae, the largest veins to enter the heart. Blood flows from the right atrium into the right ventricle. The right ventricle receives blood from the right atrium and pumps it into the pulmonary artery, which carries it to the lungs.
The left atrium receives oxygenated blood from the lungs through the four pulmonary veins. Blood flows from here into the left ventricle. The left ventricle receives blood from the left atrium. Blood then goes into the aorta, the largest of the arteries, and is pumped to all parts of the body except the lungs.

35. The Pericardium
The heart is enclosed in a double-walled membranous sac known as the pericardium
Pericardial fluid between the layers prevents friction when the heart beats
What are the upper and lower chambers of the heart? (The atria are the upper chambers and the ventricles are the lower chambers.)

36. Heart Chambers The heart functions as a double pump:
The right side pumps blood to the lungs
The left side sends blood to the rest of the body
The coronary vessels supply blood to the heart muscle
Each side is subdivided into an upper and a lower chamber
Describe the upper and lower chambers. (The upper chambers, the atria, receive blood. The ventricles, the lower chambers, pump blood.)

37. Heart Valves
One-way valves prevent the backflow of blood and separate the chambers of the heart by opening and closing with each heartbeat
The tricuspid valve is found between the right atrium and the right ventricle
The mitral valve has two cusps and lies between the left atrium and the left ventricle
Two semilunar valves have three crescent-shaped flaps
Pulmonary semilunar valve allows blood to flow from the right ventricle into the pulmonary artery
Aortic semilunar valve allows blood flow from the left ventricle into the aorta
These valves are responsible for the heart sounds that we hear with a stethoscope.

38. Blood Flow Through the Heart
The right atrium receives blood from the superior and inferior venae cavae
Blood flows from the right atrium into the right ventricle
The right ventricle receives blood from the right atrium and pumps it into the pulmonary artery, which carries it to the lungs
The left atrium receives oxygenated blood from the lungs through the four pulmonary veins
Blood flows from here into the left ventricle
The left ventricle receives blood from the left atrium
Blood then goes to the aorta, and is pumped to all parts of the body, except the lungs
Where does the right ventricle pump blood to next? (Blood is pumped to the lungs from the right ventricle.)

39. Blood Vessels
Arteries are large blood vessels that carry blood away from the heart to all regions of the body
Capillaries are a system of microscopic vessels that connect the arterial and venous systems
Veins form a low-pressure collecting system to return the waste-filled blood to the heart
Which way do arteries run in relation to the heart? (Arteries run away from the heart.)
Which way do veins run in relation to the heart? (Veins run toward the heart.)
Where are capillaries located in relation to the arteries and veins? (The capillaries form a system of microscopic vessels that connect the arterial and venous systems.)

40. Coronary Vessels
The heart functions as a double pump: The right side pumps blood to the lungs, and the left side sends blood to the rest of the body.
The right atrium receives blood from the superior and inferior venae cavae, the largest veins that enter the heart. Blood flows from the right atrium into the right ventricle. The right ventricle receives blood from the right atrium and pumps it into the pulmonary artery, which carries it to the lungs. The left atrium receives oxygenated blood from the lungs through the four pulmonary veins. Blood flows from here into the left ventricle. The left ventricle receives blood from the left atrium. Blood then goes into the aorta.
From Applegate EJ: The anatomy and physiol­ogy learning system, ed 4, St Louis, 2011, Saunders.

41. Arteries
The arteries are the large blood vessels that carry blood away from the heart to all regions of the body. The walls of the arteries are composed of three layers. This structure makes arteries both muscular and elastic so that they can expand and contract with the pumping of the heart.
The capillaries are a system of microscopic vessels that connect the arterial and venous systems.
The veins form a low-pressure collecting system to return the waste-filled blood to the heart.
From Patton KT, Thibodeau GA: Anatomy and physiology, ed 8, St Louis, Mosby, 2013.

42. Blood and Blood Cells
Plasma is a straw-colored fluid that transports nutrients, hormones, and waste products
Plasma is 91% water
Red blood cells contain the blood protein hemoglobin, which plays an essential role in oxygen transport
White blood cells, also known as leukocytes, have the primary function of fighting disease in the body
One drop of blood contains 5 million red blood cells, 7500 white blood cells, and 300,000 platelets. The remaining 9% of plasma consists mainly of plasma proteins, including albumin and globulin.
White blood cells, also known as leukocytes, have the primary function of fighting disease in the body. Describe the five major groups of leukocytes.
(Basophils have functions that are imprecisely understood.
Eosinophils increase in number in allergic conditions.
Lymphocytes are important in the immune process, protecting the body.
Monocytes act as macrophages and dispose of dead and dying cells and other debris.
Neutrophils fight disease by engulfing germs.)

43. Blood Typing and Rh Factor
The safe administration of blood from donor to recipient requires typing and cross-matching
Blood typing is based on the antigens and antibodies found in the blood
The most important classifications are A, AB, B, and O
Patients who receive blood that is incompatible with their own may experience a serious and possibly fatal reaction
Do you know what classification of blood you have? (Answers will vary.)
If you don’t know how can you find out? (Answers will vary.)
Which type of blood is the universal donor? (Type O)
Which type is the universal recipient? (AB positive)

44. Blood Typing and Rh Factor (Cont.)
The Rh factor is an additional antigen that is present on the surfaces of red blood cells in some individuals
A person whose blood contains the factor is Rh positive
A person whose blood does not contain the factor is Rh negative
Anti-Rh antibodies are not naturally found in plasma as they are in blood types, but they do develop if the patient is exposed to the Rh factor
If an Rh-negative mother gives birth to an Rh-positive baby, she will not have a blood reaction with the first pregnancy. But, after blood is mixed during delivery, the mother will develop anti-Rh antibodies in her serum. A subsequent Rh-positive fetus may develop erythroblastosis fetalis if maternal anti-Rh antibodies react with fetal Rh antigen.

45. Lymphatic System The structures of the lymphatic system:
Lymph vessels
Lymph nodes
Lymph fluid
Lymphoid organs
Drainage vessels absorb excess protein from tissues and return it to the bloodstream
Lymphoid organs contribute to the immune system to assist with destruction of harmful microorganisms
What are the main functions of the lymphatic system? (The main functions of the lymphatic system include defense against disease and returning plasma proteins to the bloodstream.)

46. Lymph Vessels
Lymph capillaries are thin-walled tubes that carry lymph from the tissue spaces to the larger lymphatic vessels
Similar to veins, lymphatic vessels have valves that prevent the backflow of fluid
Lymph fluid always flows toward the thoracic cavity, where it empties into veins in the upper thoracic region
Specialized lymph vessels, called lacteals, are located in the small intestine
Lacteals aid in the absorption of fats from the small intestine into the bloodstream
Fluid leaves circulatory capillaries to bathe tissues and cells to keep them moist.
This same clear, light-yellow fluid, called lymph, is reabsorbed by the lymphatic system and is returned to the blood through veins.
This one-way flowing system moves fluid toward the heart.

47. Lymph Nodes
Small round or oval structures that are located in the lymph vessels
They fight disease by producing antibodies; this is part of the immune reaction
Major lymph node sites of the body include:
Cervical (in the neck)
Axillary (under the arms)
Inguinal (in the lower abdomen)
Lymph fluid
The bean-shaped lymph nodes are connected by vessels. Lymph nodes are usually present in clusters in the armpits, on either side of the neck, and in the groin.
The lymph nodes contain lymphocytes (white blood cells), which help destroy foreign bacteria and other harmful cells. The lymph nodes may become enlarged or swollen when they fight an infection, because they must produce additional white blood cells. The lymph nodes may feel tender or inflamed as they are actively fighting a foreign body. 

48. Lymphoid Organs Tonsils
Masses of lymphatic tissue that are located in the upper portions of the nose and throat, where they form a protective ring of lymphatic tissue
Nasopharyngeal tonsils are found in the nasopharynx
Palatine tonsils are located in the oropharynx between the anterior and posterior pillars of fauces
Lingual tonsils are located on the back of the tongue
All of these tonsils are removed during tonsillectomy. Why would tonsils ever be removed? (If they become infected)
Why do we have tonsils? (Tonsils place lymphocytes into the lymph to destroy microorganisms.)

49. Lymphoid Organs (Cont.)
Spleen
Produces lymphocytes and monocytes, which are important components of the immune system
It also filters microorganisms and other debris not destroyed by the lymphatic system
What else does the spleen do? (It stores red blood cells, maintains an appropriate balance between cells and plasma in the blood, and removes and destroys nonviable red blood cells.)

50. Lymphatic System
The structures of the lymphatic system include the lymph vessels, lymph nodes, lymph fluid, and lymphoid organs. Fluid leaves circulatory capillaries to bathe tissues and cells to keep them moist. This same clear light-yellow fluid, called lymph, is reabsorbed by the lymphatic system and returned to the blood through the veins.
Lymph nodes are small round or oval structures located in lymph vessels.
The spleen is the largest of the lymphoid organs. The spleen produces lymphocytes and monocytes, which are important components of the immune system. It also filters microorganisms and other debris not destroyed by the lymphatic system.
From Patton KT, Thibodeau GA: Anatomy and physiology, ed 8, St Louis, Mosby, 2013.

51. The Tonsils
The tonsils are masses of lymphatic tissue located in the upper portions of the nose and throat, where they form a protective ring of lymphatic tissue.
The nasopharyngeal tonsils, also known as adenoids, are found in the nasopharynx.
The palatine tonsils are located in the oropharynx between the anterior and posterior pillars of fauces (throat) and are visible through the mouth.
The lingual tonsils are located on the back of the tongue.

52. Nervous System
The nervous system is the communication system of the body
Instructions and directions are sent out by this system to the various organs in the body
The nervous system can be compared to computer communications, with the brain and spinal cord as the main computer and the nerves as the cables that carry messages to and from this center
The main functions of the nervous system are reception of stimuli, transmission of messages, coordination of mechanism systems, and special senses.
What are the two divisions of the autonomic nervous system? (The central nervous system and the peripheral nervous system are the two divisions.)

53. Nervous System (Cont.) Central nervous system (CNS)
The brain and the spinal cord
Peripheral nervous system (PNS)
The cranial nerves and the spinal nerves
The nervous system is composed of the CNS and the PNS.
The CNS consists of the brain and spinal cord.
The PNS consists of the cranial nerves and the spinal nerves. It also includes the autonomic nervous system, which is divided into the sympathetic and parasympathetic nervous systems.

54. Neurons
The basic function of neurons is to direct communication or nerve impulses
Neurons have the properties of excitability, the ability to respond to a stimulus, and conductivity, which refers to transmission of an impulse
There are three types of neurons:
Sensory neurons
Motor neurons
Associative neurons
What are the functions of each neuron type? (Sensory neurons emerge from the skin or sense organs and carry impulses toward the brain and spinal cord. Motor neurons carry impulses away from the brain and spinal cord and toward the muscles and glands. Associative neurons carry impulses from one neuron to another.)

55. Neurons (Cont.)
A synapse is the space between two neurons or between a neuron and a receptor organ
A neurotransmitter is a chemical substance that allows the impulse to jump across the synapse from one neuron to another
Nerves covered with myelin are referred to as white matter
Nerves that do not have the protective myelin sheath make up the gray matter of the brain and spinal cord
Some chemicals can interfere with neurotransmitters. Antidepressant medications such as selective serotonin uptake inhibitors cause serotonin to persist in the synapse to elevate mood.

56. Central Nervous System
Brain
The brain is the primary center for the regulation and coordination of the body’s activities, and each part of the brain controls different aspects of body function
Spinal cord
The spinal cord carries all of the nerves that affect the limbs and lower part of the body and is the pathway for impulses going to and from the brain
Injury to the brain:
Head injury may be caused by blunt trauma to the head or a break in the skull.
Brain tumors may be benign (noncancerous) or malignant (cancerous); a tumor’s effect on the brain and bodily functions depends on its location and whether it exerts pressure on the surrounding tissues.
Migraine headache results from vasodilation and increased blood flow to the head.
Cerebrovascular accident—commonly called a stroke—is the interruption of blood flow to the brain. It results in numbness, altered mental status, vertigo, and loss of muscle coordination. Stroke may be caused by a hemorrhage or a blood clot.

57. Peripheral Nervous System
The autonomic nervous system controls unconscious activities such as breathing, heart rate, body temperature, blood pressure, and pupil size
The somatic nervous system controls conscious activities
What system controls breathing? (Autonomic nervous system)
What system controls walking? (Somatic nervous system)
What system controls whether or not you sweat? (Autonomic nervous system)
What system controls speaking? (Somatic nervous system)

58. The Central Nervous System (CNS)
The nervous system is the communication system of the body. Instructions and directions are sent out by this system to the various organs in the body.
The CNS consists of the brain and spinal cord.
The PNS consists of the cranial nerves and the spinal nerves.
The PNS also includes the autonomic nervous system, which is divided into the sympathetic and parasympathetic nervous systems.
From Patton KT, Thibodeau GA: Anatomy and physiology, ed 8, St Louis, Mosby, 2013.

59. Lesson 7.3
Respiratory, Digestive, Endocrine, Urinary, Integumentary, and Reproductive Systems
Locate the respiratory system; explain its purpose, components, and functions; and describe the signs and symptoms of its common disorders.
Locate the digestive system; explain its purpose, components, and functions; and describe the signs and symptoms of its common disorders.
Locate the endocrine system; explain its purpose, components and functions; and describe the signs and symptoms of its common disorders.

60. Lesson 7.3
Respiratory, Digestive, Endocrine, Urinary, Integumentary, and Reproductive Systems
Locate the urinary system; explain its purpose, components, and functions; and describe the signs and symptoms of its common disorders.
Locate the integumentary system; explain its purpose, components, and functions; and describe the signs and symptoms of its common disorders.
Locate the reproductive system; explain its purpose, components, and functions; and describe the signs and symptoms of its common disorders.
Give examples of conditions that require interaction among body systems.

61. Respiratory System
Delivers oxygen to the millions of cells in the body and transports the waste product carbon dioxide out of the body
The respiratory system consists of the:
Nose
Paranasal sinuses
Pharynx
Epiglottis
Larynx
Trachea
Alveoli
Lungs
The main functions of the respiratory system are transport of oxygen to cells and excretion of carbon dioxide, as well as some water and waste.
The larynx, also known as the voice box, contains the vocal bands, which make speech possible.
Air passes from the larynx to the trachea. The trachea extends from the neck into the chest, directly in front of the esophagus.
The trachea divides into two branches called bronchi. Each bronchus leads to a lung, where it divides and subdivides into increasingly smaller branches; bronchioles are the smallest of these branches. Alveoli are the tiny grapelike clusters found at the end of each bronchiole. During respiration, the exchange of gases between the lungs and the blood takes place in the alveoli.

62. Nose
Air enters the body through the nostrils of the nose and passes through the nasal cavity
The nose is divided by a wall of cartilage called the nasal septum
The nose and the respiratory system are lined with mucous membrane, a specialized form of epithelial tissue
Incoming air is filtered by the cilia, which are thin hairs that are attached to the mucous membrane just inside the nostrils
Mucus secreted by the mucous membranes helps to moisten and warm the air as it enters the nose.

63. Pharynx
After passing through the nasal cavity, air reaches the pharynx, which is commonly known as the throat
There are three divisions of the pharynx:
The nasopharynx is located behind the nose and above the soft palate
The oropharynx extends from the soft palate above to the level of the epiglottis below
The laryngopharynx extends from the level of the epiglottis above to the larynx below
What is the name for the narrow tube that leads from the middle ear into the nasopharynx? (The eustachian tube. This is why you swallow or chew gum to equalize air pressure when landing in an airplane.)

64. Epiglottis
The oropharynx and the laryngopharynx serve as a common passageway for food from the mouth and air from the nose
During swallowing, the epiglottis acts as a lid and covers the larynx so that food does not enter the lungs
What do you think would happen if food entered the lungs? (Answers will vary.)

65. Larynx
Also known as the voice box, it contains the vocal bands, which make speech possible
The larynx is protected and is held open by a series of cartilaginous structures
The largest cartilage forms the prominent projection in front of the neck, called the “Adam’s apple”
Males have an Adam's apple.

66. Trachea Air passes from the larynx to the trachea
The trachea extends from the neck into the chest, directly in front of the esophagus
It is protected and held open by a series of C-shaped cartilaginous rings
Where does the trachea terminate? (The trachea terminates as it divides into two branches called bronchi, which each lead to a lung.)

67. Lungs The trachea divides into two branches called bronchi
Each bronchus leads to a lung, where it divides and subdivides into increasingly smaller branches; bronchioles are the smallest of these branches
Alveoli are tiny grapelike clusters found at the end of each bronchiole
Exchange of gases between the lungs and the blood takes place in the alveoli
Oxygen from the air passes through the thin walls of the alveoli into the bloodstream, and carbon dioxide passes from the blood into the alveoli to be expelled into the air.

68. Structure of the Respiratory System
Air enters the body through the nostrils (nares) of the nose and passes through the nasal cavity. The nose is divided by a wall of cartilage called the nasal septum. The nose and respiratory system are lined with mucous membrane, which is a specialized form of epithelial tissue.
The incoming air is filtered by the cilia, thin hairs attached to the mucous membrane just inside the nostrils. Mucus secreted by the mucous membranes helps to moisten and warm the air as it enters the nose.
From Patton KT, Thibodeau GA: Anatomy and physiology, ed 8, St Louis, Mosby, 2013.

69. Digestive System
The role of the digestive system is to provide the body with the nutrients, water, and electrolytes necessary for life
The digestive system functions under involuntary control
The main functions of the digestive system are digestion of food, absorption of nutrients, and elimination of solid wastes.

70. Digestive Process Ingestion: Occurs when food is taken into the mouth
Digestion: Begins in the mouth as food is masticated with saliva and then swallowed
Movement: The chewed food is subjected to peristalsis, the rhythmic wavelike contractions that move the food through the digestive tract
Absorption: The nutritional elements in the gastrointestinal tract pass through the lining of the gastrointestinal tract and into the bloodstream
Elimination: In the large intestine, the solid by-products of digestion are eliminated from the body in feces
These five actions provide the body with the nutrition it needs.

71. Structures of the Digestive System
The major structures of the digestive system are the:
Mouth
Pharynx
Esophagus
Stomach
Small intestine
Large intestine
Liver, gallbladder, and pancreas
See the figure on the next slide to see where these structures are located.

72. Major Structures of the Digestive System
The major structures of the digestive system are the mouth, pharynx, esophagus, stomach, small intestine, large intestine, liver, gallbladder, and pancreas.
The digestive system works like an assembly line in reverse. It takes in whole foods and breaks them down into their chemical components. Food that has been eaten is broken down by digestive juices into small absorbable nutrients that generate energy and provide the body with the nutrients, water, and electrolytes necessary for life. The digestive system functions under involuntary control.
From Applegate EJ: The anatomy and physiology learning system, ed 4, St Louis, Saunders, 2011.

73. Endocrine System
The endocrine system consists of ductless glands and tissues that help regulate the body’s activities
The glands secrete hormones directly into the blood
These hormones affect metabolism, growth, and development
The hormones are secreted directly into the bloodstream, not through a duct
Studies now show that a relationship exists between periodontal disease and diabetes (an endocrine disease) and its control.
What is diabetes? (Diabetes mellitus is a chronic disease involving abnormalities in the body’s ability to use sugar. Diabetes is characterized by:
Increased blood sugar concentrations for months or years.
Both hereditary and environmental factors leading to the development and progression of diabetes.
A relative or absolute deficiency of effective circulating insulin. Insulin is a substance made by the pancreas that lowers blood sugar in conjunction with meals.)

74. Endocrine Glands Thyroid gland Parathyroid gland Ovaries Testes
Pituitary gland
Pancreas
Adrenal medulla
The major endocrine glands are scattered throughout the body but are considered to function as one system

75. Endocrine Glands
Endocrine glands include the thyroid gland, the parathyroid gland, the ovaries, the testes, the pituitary gland, the pancreas, and the adrenal medulla.
The endocrine system uses chemical messengers called hormones that move through the bloodstream and can reach every cell in the body. Hormones help maintain a constant environment inside the body (homeostasis), adjusting the amount of salt and water in the tissues and sugar in the blood to suit the conditions at a particular time. Hormones produce both long-term changes, such as a child’s growth and sexual maturation, and rhythmic ones, such as the menstrual cycle.
From Patton KT, Thibodeau GA: Anatomy and physiology, ed 8, St Louis, Mosby, 2013.

76. Urinary System
The urinary system is also known as the excretory system
Its principal function is to maintain fluid volume and composition of the body fluids
Waste products leave the body in the form of urine, and the needed substances are returned to the blood
Why is it important that we get enough fluids in our body during the day? (Fluid balance of the body must be maintained.)

77. Organs of the Urinary System
The kidneys are the site of formation of urine, which carries waste materials away from the blood
The ureters transport the urine from the kidney
The bladder stores urine until it can be disposed of
The urethra is the conduit through which the bladder is emptied during the process of urination
Kidney disease results from damage to the nephrons, the tiny structures inside your kidneys that filter blood. Usually the damage occurs very gradually, over the course of years; it happens in both kidneys. Kidney disease is often asymptomatic.
Common causes of kidney disease:
In diabetes mellitus, the glucose stays in your blood and acts like a poison.
High blood pressure can damage the small blood vessels in the kidneys. When this happens, the kidneys cannot filter wastes from the blood very well.
Some kidney diseases result from hereditary factors and run in families. If your family has a history of any kind of kidney problems, you may be at risk for kidney disease and should talk to your doctor.

78. The Urinary System
The kidneys require a large blood supply and are connected close to the body’s main artery, the aorta.
From Patton KT, Thibodeau GA: Anatomy and physiology, ed 8, St Louis, Mosby, 2013.

79. Integumentary System
The skin is the body’s first line of defense against disease
Functions of the skin system:
Helps regulate body temperature
Provides a barrier that prevents bacteria from entering the body
Excretes liquids and salts
Provides sensitivity to touch
Uses ultraviolet rays from the sun to convert chemicals into vitamin D necessary for absorption of calcium
What are the functions of the skin? (See the bullet points on this slide.)
What is calcium used for in the body? (Calcium is essential to the formation and maintenance of strong bones and teeth. In the human adult, bone calcium chiefly takes the form of the phosphate and carbonate salts. A sufficient store of vitamin D in the body is necessary for the proper utilization of calcium. Calcium also functions in the regulation of the heartbeat and in the conversion of prothrombin to thrombin, a necessary step in the clotting of blood.)
What is skin cancer? (Skin cancer is the uncontrolled growth of skin cells. Left unchecked, these cancerous cells can spread from the skin into other tissues and organs.)

80. Skin Structures The skin is composed of different layers, including:
Epidermis
The outer layer of the skin; has no blood supply of its own
Dermis
Contains many free nerve endings and receptors, which allow for detection of touch, temperature, and pain
Subcutaneous fat
A layer of loose connective tissue that anchors the skin to underlying organs; insulates the body against heat loss and cushions underlying organs
How does the epidermis receive nutrition? (Cells of the epidermis receive their nutrients from vessels in the underlying tissue.)

81. Skin Appendages Hair Nails Glands
Enclosed in a follicle and consists of a root and a shaft
Nails
Contains a root and a body
Glands
Sebaceous glands
Sudoriferous glands
Apocrine sweat glands
What determines hair color and skin color? (Melanin produced in the epidermis)

82. Female Reproductive System
External
Mons pubis
Labia majora and minora
Vulva
Clitoris
Internal
Ovaries
Fallopian tubes
Uterus
Vagina
The female reproductive system consists of the external and internal genitalia. The external genitalia consist of the mons pubis, labia majora and labia minora, vulva, and clitoris. The internal genitalia consist of the ovaries, fallopian tubes, uterus, and vagina.
Fertility, the normal function of the reproductive system, begins at puberty (the onset of menstruation) and ceases at menopause. Many disorders can affect the female reproductive system.
What is the uterus? (It is the womb, a pear-shaped organ in women that holds and nourishes the growing embryo and fetus. The uterus has three areas: the body, or upper part; the isthmus, or narrowed central area; and the cervix, the lowest portion.)

83. Male Reproductive System
Produces and transports sperm
In the male, several organs serve as parts of both the urinary tract and reproductive system
This system consists of the:
Excretory ducts
Testes
Prostate
Seminal vesicles
The male reproductive system consists of the testes, excretory ducts, and accessory organs. The accessory organs include the prostate and seminal vesicles. In the male, several organs serve as parts of both the urinary tract and the reproductive system.
Certain disorders may interfere with the function of either system or both systems.
What is the prostate? (A gland in the male that surrounds the neck of the bladder and urethra. The prostate contributes to the seminal fluid.)

84. Interaction Among the 10 Body Systems
Body systems do not operate independently
Exert important effects on each other
Something happening to one system tends to affect other systems
For example, when you exercise hard, your muscular system needs extra oxygen, so your respiratory system works harder than usual to supply it.

85. Questions?