Physiology of the Skeletal and Muscular Systems
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Chapter 7 General Physiology
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. Lesson 7.1
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
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
Skeletal System • There are 206 bones in the human body • For descriptive purposes, the skeleton is divided into the axial and appendicular skeletal systems
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
The Skeletal System From Patton KT, Thibodeau GA: Anatomy and physiology, ed 8, St Louis, Mosby, 2013.
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
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
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
Kinds of Bone • Compact 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
Cortical Bone Appears Hard and Dense From Haring JI, Lind LJ: Radiographic interpretation for the dental hygienist, Philadelphia, Saunders, 1993.
Trabeculae • Bony spicules in cancellous bone that form a mesh of intercommunicating spaces filled with bone marrow • Appear as a weblike structure on radiographs
Cancellous Bone Containing Trabeculae From Haring JI, Lind LJ: Radiographic interpretation for the dental hygienist, Philadelphia, Saunders, 1993.
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
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
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
Types of Joints From Gerdin J: Health careers today, ed 5, St Louis, Mosby, 2012.
Types of Joints From Gerdin J: Health careers today, ed 5, St Louis, Mosby, 2012.
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
Muscles of the Body, Anterior View From Applegate EJ: The anatomy and physiology learning system, ed 4, St Louis, 2011, Saunders.
Muscles of the Body, Posterior View From Applegate EJ: The anatomy and physiology learning system, ed 4, St Louis, 2011, Saunders.
Types of Muscles • Striated 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
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
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
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
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
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. Lesson 7.2
Cardiovascular System • Consists of the: • Circulatory system • Heart • Lymphatic system • These systems provide life-sustaining capabilities for the survival of body cells and tissues
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
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
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
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
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
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
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
Coronary Vessels From Applegate EJ: The anatomy and physiology learning system, ed 4, St Louis, 2011, Saunders.
Arteries From Patton KT, Thibodeau GA: Anatomy and physiology, ed 8, St Louis, Mosby, 2013.
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
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
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
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
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
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
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
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
Lymphatic System From Patton KT, Thibodeau GA: Anatomy and physiology, ed 8, St Louis, Mosby, 2013.
