Chapter 8
Skeletal System
Elsevier items and derived items © 2007, 2003, 2000 by Saunders, an imprint of Elsevier Inc.
Slide 1
Introduction
• The skeletal system supports the weight of the
body, supports and protects body organs,
enables the body to move, acts as storage site
for minerals, and produces blood cells.
Slide 2
Bones: An Overview
• Sizes and Shapes
– Bones are classified as long, short, flat, and irregular.
– Bone markings function as sites of muscle attachments and passages
for nerves and blood vessels.
– A long bone has a diaphysis (shaft) and two epiphyses (ends). Articular
cartilage is found on the outer surface of the epiphyses.
– The diaphysis is composed of compact or hard bone. The epiphysis
consists of spongy or soft bone; red marrow is found in the holes of
spongy bone.
Slide 3
Bones: An Overview - cont’d
• Bone Formation and Growth
– Bones ossify in two ways. In the skull, osteoblasts
replace thin connective tissue membrane, forming flat
bones. Other bones form on hyaline cartilage models
as osteoblasts replace cartilage with bone.
– Bones grow longitudinally at the epiphyseal disc, to
determine height; bones also grow thicker and wider
to support the weight of the body.
– Bone growth and reshaping occur throughout life and
depend on many factors, including diet, exercise, and
hormones.
Slide 4
Divisions of the Skeletal System
• The names of the 206 bones of the skeleton
are listed in Table 8-2.
Slide 5
Divisions of the Skeletal System - cont’d
• Axial Skeleton
– The axial skeleton includes the bones of the skull
(cranium and face), hyoid bone, bones of the
middle ear, bones of the vertebral column, and
the thoracic cage.
– The skull of a newborn contains fontanels, which
are membranous areas that allow brain growth.
– The skull contains air-filled cavities called sinuses.
Slide 6
Divisions of the Skeletal System - cont’d
• Axial Skeleton—cont’d
– The vertebral column is formed from 26
vertebrae, one sacrum, and one coccyx. The
vertebrae are separated by cartilaginous discs. The
vertebral column of the adult has four curvatures:
cervical, thoracic, lumbar, and sacral.
– The thoracic cage is a bony, cone-shaped cage
formed by the sternum, 12 pairs of ribs, and
thoracic vertebrae.
Slide 7
Divisions of the Skeletal System - cont’d
• Appendicular Skeleton
– The appendicular skeleton includes the bones of
the extremities (arms and legs), and the bones of
the hip and shoulder girdles.
– The shoulder girdle consists of the scapula and the
clavicle.
– The pelvic girdle is formed by the two coxal bones
and is secured to the axial skeleton at the sacrum.
Slide 8
Joints
• A joint or articulation is the site where two
bones meet.
Slide 9
Joints - cont’d
• Types of Joints
(based on the degree of movement)
– Immovable joints.
– Slightly movable joints.
– Freely movable joints or synovial joints. Structures
within a synovial joint (knee): articular cartilage,
the joint capsule, synovial membrane, synovial
fluid, bursae, and supporting ligaments.
– The types of freely movable joints include hinge,
ball and socket, pivot, gliding, saddle, and
Slide 10
condyloid.
Joints - cont’d
• Joint Movement
– Freely movable joints are capable of different
types of movement.
– Types of movements at freely movable joints
include flexion and extension, abduction and
adduction, inversion and eversion, supination
and pronation, and circumduction.
Slide 11
Introduction
• The integumentary system includes the skin,
which covers the body, protects the internal
organs, and plays an important role in the
regulation of body temperature.
Slide 12
Structures: Organs of the
Integumentary System
• The integumentary system includes the skin,
accessory structures, and subcutaneous tissue
beneath the skin.
Slide 13
Structures: Organs of the
Integumentary System - cont’d
• Skin
– The skin is called the cutaneous membrane.
– The skin has two layers, an outer layer called the
epidermis and an inner layer called the dermis.
– The epidermis has five layers. The stratum
germinativum is the layer in which cell division takes
place. The new cells produce keratin (waterproofing)
and die as they are pushed toward the surface. The
outer layer is the stratum corneum and consists of
flattened, dead, keratinized cells.
Slide 14
Structures: Organs of the
Integumentary System - cont’d
• Skin—cont’d
– The dermis lies on the subcutaneous tissue.
– Skin color is determined by many factors: some
genetic, some physiologic, and some due to disease.
Melanin causes skin to darken. Carotene causes skin
to appear yellow. The amount of blood in the skin
affects skin color (e.g., flushing) as does the
appearance of abnormal substances such as
bilirubin (jaundice) and a low blood oxygen content
(cyanosis).
Slide 15
Structures: Organs of the
Integumentary System - cont’d
• Accessory Structures of the Skin
– Hair is unevenly distributed over the skin. The location
of the hair determines its function. Eyebrows and
eyelashes protect the eyes from dust and perspiration.
– The main parts of a hair are the shaft and root.
– Hair color is determined by the amount and type of
melanin.
– Nails are thin plates of stratified squamous epithelial
cells that contain a hard form of keratin.
– There are two major exocrine glands in the skin:
sebaceous glands and sweat glands.
Slide 16
Structures: Organs of the
Integumentary System - cont’d
• Accessory Structures of the Skin—cont’d
– The sebaceous glands (oil glands) secrete sebum. The
sebum lubricates hair and skin. In the fetus, these
glands secrete vernix caseosa, a cheeselike substance
that coats the skin of a newborn.
– The two types of sweat glands (sudoriferous glands)
are the apocrine glands and the eccrine glands. The
eccrine sweat glands play a crucial role in temperature
regulation.
– The mammary glands (which secrete milk) and the
ceruminous glands (which secrete ear wax) are
modified sweat glands.
Slide 17
Structures: Organs of the
Integumentary System - cont’d
• Subcutaneous Tissue
– Subcutaneous tissue anchors the dermis to
underlying structures.
– Subcutaneous tissue acts as an insulator; it
prevents heat loss.
Slide 18
Regulation of Body Temperature
• Heat Production
– Heat produced by metabolizing cells constitutes
the body temperature.
– Most of the heat is produced by the muscles and
the liver.
• Heat Loss
– Most of the heat (80%) is lost through the skin.
– Heat loss occurs through radiation, conduction,
convection, and evaporation.
Slide 19
Regulation of Body Temperature - cont’d
• Heat Loss—cont’d
– Normal body temperature is set by the body’s
thermostat in the hypothalamus.
– Heat is lost through sweating and vasodilation.
Heat is conserved by vasoconstriction and
produced by shivering.
Slide 20
When Skin Is Burned
• Physiological Effects
– Short-term effects: fluid and electrolyte losses,
shock, inability to regulate body temperature,
infection
– Long-term effects: scarring, loss of function, and
cosmetic and emotional problems
• Classification of Burns
– Classified according to the thickness of the burn
(partial, full); also first, second, and third degree.
– The rule of nines is a way to evaluate burns.
Slide 21
Introduction
• Tissues are groups of cells similar to each
other in structure and function.
• Membranes are thin sheets of tissue that
cover surfaces, line body cavities, and
surround organs.
Slide 22
Types of Tissue
• Epithelial Tissue Types
– Epithelial tissue covers surfaces, lines cavities, and
engages in secretion/absorption and protective
functions.
– Epithelial tissue is classified according to cell shape
(squamous, cuboidal, and columnar) and layers
(simple and stratified).
– The types and functions are summarized in Table 61.
Slide 23
Types of Tissue - cont’d
• Connective Tissue
– The primary function of connective tissue is to bind
together the parts of the body. Other functions
include support, protection, fat storage, and transport
of substances.
– Connective tissue has an abundant intercellular matrix
that fills spaces between cells. The intercellular matrix
may be liquid, gel-like, or hard. The matrix often
contains protein fibers that are secreted by the cells.
– There are three types of loose connective tissue:
areolar, adipose, and reticular.
Slide 24
Types of Tissue - cont’d
• Connective Tissue—cont’d
– Dense fibrous connective tissue forms tendons, ligaments,
capsules, and fascia, and is found in the skin (dermis).
– Types of cartilage include: hyaline, elastic, and
fibrocartilage.
– Bone (osseous tissue) is connective tissue formed by
osteocytes. Bone cells have a hard intercellular matrix that
includes collagen, calcium salts, and other minerals.
– Blood and lymph are types of connective tissue that have a
watery intercellular matrix.
Slide 25
Types of Tissue - cont’d
• Nervous Tissue
– Nervous tissue is found in the peripheral nerves,
brain, and spinal cord.
– The two types of nervous tissue are neurons,
which transmit electrical signals, and neuroglia,
which support and take care of the neurons.
• Muscle Tissue
– Muscle cells contract, thereby causing movement.
– The three kinds of muscle are skeletal, smooth,
and cardiac.
Slide 26
Tissue Repair
• Tissue Repair by Regeneration
– Replacement of tissue by cells that undergo
mitosis
• Tissue Repair by Fibrosis
– Formation of scar tissue
Slide 27
Membranes
• Epithelial Membranes
– The cutaneous membrane is the skin.
– Mucous membranes are epithelial membranes that line all
body cavities that open to the exterior of the body.
– Serous membranes are epithelial membranes that line the
ventral body cavities, which are not open to the exterior of
the body.
– Serous membranes form two layers: a parietal layer that lines
the wall of the cavity and a visceral layer that covers the
outside of an organ.
– The three serous membranes are the pleura, the
pericardium, and the peritoneum.
Slide 28
Membranes - cont’d
• Connective Tissue Membranes
– Synovial membranes are connective tissue
membranes.
– Other connective tissue membranes are listed in
Table 6-3.
Slide 29