skeletal system chapter 6. objectives 1.identify the different structures and fuctions of the...
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Skeletal System
Chapter 6
Objectives
1. Identify the different structures and fuctions of the Skeletal system.
2. Label a long bone and internal structures of bone.
3. Explain bone development and growth.4. Apply knowledge of homeostatic
mechanisms to explain the regulation of blood calcium levels.
Introduction
• Bones are very active tissues• Each bone is made up of several types of
tissues and is an organ
Skeletal System Components
• Bone• ________________-
connect bones to muscle
• ________________-connect bones to bones
Functions
• ___________________ attachment
• Protection• Contain ___________-
producing cells• Storage of inorganic salts• Passageway for
___________ & blood vessels
Types of Bone Tissue
• _____________________ bone: homogeneous
• _________________ bone: small needle-like pieces of bone; many open spaces
Classification of Bones
Long Bones • Characteristics: Typically
_________________ than they are ______________, have a shaft with heads at both ends
• Structure: contain mostly ____________________ bone
• Examples: – Humerus, Femur, Ulna, Radius,
Clavicle, Phalanges
Short Bones
• Characteristics: Generally _________________-shaped
• Structure: contain mostly ___________________ bone
• Examples: – ______________ bones– Foot bones
Flat Bones • Characteristics:
_____________, flattened, and usually __________________
• Structure: two thin layers of _________________ bone surrounding a layer of _______________ bone
• Example:– Scapula – Sternum
Irregular Bones
• Characteristics: ___________________ shape, do not fit into other bone classification categories
• Example:– ____________________– vertebra
Bone Classification
• Sesmoid
Long Bone Anatomy
Bone Structure• Bones differ in size and shape, yet are similar in
several ways• Parts of a long bone– _________________________ – expanded ends of
bones that form _________________ with adjacent bones
– _______________________ cartilage (hyaline cartilage) – covers the epiphysis
– _________________________ – the shaft of the bone– _______________________________ – a tough layer of
vascular connective tissue that covers the bone and is continuous with ligaments and tendons
Parts of a long bone• A bone’s shape makes possible its function• Bony ________________________ or grooves
indicate places of attachment for muscles• ____________________ bone makes up the wall of
the ______________________• The ______________________ are filled with
__________________ bone to reduce the weight of the skeleton
• The diaphysis contains a hollow medullary cavity that is filled with _______________________
Microscopic Structure
• Compact (Cortical) Bone: __________________ and layers of ECM are concentrically clustered around a ________________________ Canal (Osteon). – Haversian Canals contain
_______________ vessels and nerve fibers which nourish the bone cells.
Microscopic structure
• ________________________ – bone cells that are located within ______________________ that lie in concentric circles around osteonic canals
• Intercellular material consists of _______________________ and inorganic _________________
• In compact bone, osteocytes and intercellular material are organized into ___________________ that are cemented together.
Microscopic structure
• __________________________________ contain blood vessels and nerve fibers and extend longitudinally through bone.
• Osteonic canals are interconnected by transverse perforation canals.
• Unlike __________________ bone, the osteocytes and intercellular material in ____________________ bone are not arranged around osteonic canals.
Microscopic structure
Microscopic Structure
Bone Growth and Development
• Osteoclasts – break down cartilage and bone• Osteoblasts – bone-building cells• Osteocytes – bone cells
Bone Development
• Intramembranous Bones:– Originate between
sheetlike layers of connective tissue.
• Endochondral Bones:– Begin as masses of
cartilage that bone tissue replaces.
Bone Development
• Intramembranous Ossification:1. Connective tissue appears at the sites of future bones. 2. Connective tissue cells differentiate into osteoblasts.3. Osteoblasts deposit bony material around themselves and form spongy bone.4. Membranous tissue cells give rise to the periosteum.5. Osteoblasts inside the periosteum form compact bone.
Intramembranous Bones
Bone Development• Endochondral Ossification (Condensed Version):
1. Cartilage breaks down in the center of the diaphysis. (primary ossification center)
2. Periosteum forms around the developing dipahysis from connective tissue.3. Blood vessels and osteoblasts from periosteum invade the cartilage and
form spongy bone.4. Epiphysis remain cartilaginous and later secondary ossification centers
appear and form spongy bone.5. Epiphyseal plate undergoes mitosis and produces new cells which enlarge ,
while calcium salts accumulate in the extracellular matrix, they calcify, and the cartilage cells die.
6. Osteoclasts secrete acid that dissolves part of the calcified matrix and osteoblasts deposit new bone tissue in place of the calcified cartilage.
7. Bone continues to grow at the epiphyseal plate until adulthood.
Endochondral Ossification
Objectives
• To explain the different functions of bone in detail.
• To apply your knowledge of homeostasis and negative feedback loops to explain hormonal regulation of bone calcium resorption and deposition.
Bone Functions
• Support and Protection– Bones give shape to the head, thorax, and limbs– The pelvis and lower limbs provide support for the
body– Bones of the skull protect the brain, ears and eyes
• Movement– Muscles attach to bones– Push and pull bones for movement
Bone Functions• Blood cell Formation– Two kinds of marrow occupy the medullary cavities of
bone• Red marrow – formation of red blood cells, white blood cells
and platelets• Yellow marrow – stores fat
• Storage of Inorganic Salts– Bone stores inorganic mineral salts in the form of
calcium phosphate– Calcium in bone is a reservoir for body calcium• When blood levels of calcium are low, osteoclasts release
calcium from bone.• Calcium is stored in bone under the influence of calcitonin
when blood levels of calcium are high.
Hematopoiesis
• Hematopoeiesis=Red blood cell formation• RBC’s form in the liver, spleen, and bone marrow– Red Marrow:
• Found in infants as well as in spongy bone of skull, ribs, sternum, clavicles, vertebrae, and hip bones of adults
• Produces red blood cells (erythrocytes), white blood cells (leukocytes), and platelets.
– Yellow Marrow:• In adults• Stores fat• *doesn’t produce RBC’s
Inorganic Salt Storage
• ECM of bone is rich in calcium• Calcium is required for muscle contraction,
nerve impulse conduction, blood clotting, and other physiological processes.
• Our bodies must maintain a sufficient blood-calcium level using a homeostatic mechanism.
Calcium Regulation
Low calcium levels
• Causes Parathyroid Hormone (PTH) to be released– PTH causes stored calcium in bone to be released– PTH causes calcium reabsorption in the kidney
(not excreted in urine)– PTH causes the synthesis of Vit. D. which increases
Ca+ absorption in the small intestines.
High calcium levels
• Causes the release of calcitonin from the thyroid gland– Calcitonin Inhibits Ca2+ absorption by the
intestines– Inhibits osteoclast activity in bones– Inhibits renal tubular cell reabsorption of Ca2+
allowing it to be excreted in the urine
Hypo vs. Hypercalcemia
• Hypocalcemia: can cause muscle stiffness and seizures
• Hypercalcemia: too much calcium, causes kidney stones or even kidney failure, could cause heart problems
Bone Fractures
• Definition: break in a bone• Types of bone fractures– Closed (simple) fracture – break that does not
penetrate the skin– Open (compound) fracture – broken bone
penetrates through the skin• Treatment: reduction and immobilization
Common types of Fractures
Repair of Bone fractures
• Steps in repair of bone fractures 1. Hematoma: blood-filled swelling is formed2. Fibrocartilage callus: break is connected by
fibrocartilage3. Bony Callus: fibrocartilage replaced by
spongy bone4. Bone remodeling: permanent healing
Repair of Bone fractures
Hematoma
Externalcallus
Bonycallus ofspongybone
Healedfracture
Newbloodvessels
Internalcallus(fibroustissue andcartilage)
Spongybonetrabecula
Hematomaformation
Fibrocartilagecallus formation
Bony callusformation
Bone remodeling
Curve of the Spine
• The spine has a normal curvature• Primary curvatures: curvatures of the thoracic
and sacral regions– Present from birth
• Secondary curvatures: spinal curvatures of the cervical and lumbar regions– Develop after birth
Skeletal changes throughout life
• Osteoporosis– Bone-thinning disease afflicting • 50% of women over age 65• 20% of men over age 70
– Disease makes bones fragile and bones can easily fracture
– Vertebral collapse results in kyphosis (also known as dowager’s hump)
– Estrogen aids in health and normal density of a female skeleton
Skeletal changes throughout life
Skeletal changes throughout life
Objectives
• To Identify the major bones of the skull. • To label the major features of the bones of the
skull.
Skeletal Organization
• Axial Skeleton– Consists of the skull, hyoid bone, vertebral column
and thorax (ribs and sternum)• Appendicular Skeleton– Consists of the pectoral girdle (scapula and
clavicle), upper limbs, pelvic girdle (coxal bones) and lower limbs
Skeletal Organization
The Skull!!
• Structure: made up of two sets of bones– Cranium– Facial bones
• Bones are joined by sutures
Human Skull, Lateral View
Human Skull, Superior View
Human Skull, Inferior View
Human Skull, Anterior View
Paranasal Sinuses
• Structure: hollow portions of bones surrounding the nasal cavity
• Functions:– Lighten the skull– Amplify voice
Paranasal Sinuses
The Vertebral Column
• Structure: 24 single vertebral bones separated by intervertebral discs– Cervical vertebrae: 7 in neck– Thoracic vertebrae: 12 in chest region– Lumbar vertebrae: 5 in lower back– Sacrum and coccyx: 9 fused vertebrae in gluteal
region
The Vertebral Column
Superior view of vertebrae
Atlas and Axis
• Structure: most superior vertebrae– Atlas: C1– Axis: C2
• Function: form joint connecting skull and spine; allow for movement of head
Regional characteristics of vertebrae
Regional characteristics of vertebrae
Regional characteristics of vertebrae
Regional characteristics of vertebrae
Sacrum and coccyx
The Bony Thorax
• Structure: made of three parts1. Sternum2. Ribs• True ribs (pairs 1-7)• False ribs (pairs 8-12)• Floating ribs (pairs 11-12)
3. Thoracic vertebrae • Function: forms a cage to protect major
organs
The Bony Thorax
Male and Female Pelvis
• Differences in male and female pelvis aid in childbirth– Female inlet is larger and more cicular– Female pelvis as a whole is shallower and the bones
are lighter and thinner– Female ilia flare more laterally– Female sacrum is shorter and less curved– Female ischial spines are shorter and further apart– Female pubic arch is more founded because the angle
of the pubic arch is greater
Joints
• The functional junctions (articulations) between bones
• Enable a wide variety of body movements• Can be classified according to the degree of
movement possible:– Immovable– Slightly movable– Freely movable
Joints
• Can also be classified according to the type of tissue that binds them together:– Fibrous– Cartilaginous– Synovial
Fibrous Joints• Held together by dense
connective tissue• Immovable or only
slightly moveable– Examples:• Sutures of the skull
(immovable)• Joint between the
distal tibia and fibula (slightly movable)
Cartilaginous Joints
• Hyaline cartilage or discs of fibrocartilage unite the bones in cartilaginous joints– Example: intervertebral
disks
Synovial Joints • Makes up most joints of the skeletal• More complex than fibrous or cartilaginous
joints• Articular ends of bone in a synovial joint are
covered with hyaline cartilage• Articulating surfaces within the joint are
lubricated with synovial fluid• Are classified (and named) based on the
shapes of their parts and the movements they permit
Ball and Socket Joint• Consists of a bone with
a globular or egg-shaped head articulating with the cup shaped cavity of another bone
• Permits a very wide range of motion
• Examples:– Hip and Shoulder Joints
Condyloid Joint
• Consists of an ovoid condyle fitting into an elliptical cavity
• Permits a wide variety of motions
• Example:– Joint between a
metacarpal and a phalange
Gliding Joints
• Occur where articulating surfaces are nearly flat or slightly curved
• Permits a “back and forth” motion
• Example:– Joints of the wrist and
ankle
Hinge Joint
• Occurs where a convex surface fits into a concave surface
• Movement is in one plane only
• Example:– Elbow and phalange
joints
Pivot Joint
• Occurs where a cylindrical surface rotates within a ring of bone and fibrous tissue
• Example:– Joint between the
proximal ends of the radius and ulna
Saddle Joint
• Forms where articulating surfaces have both concave and convex areas
• Permits a wide range of movements
• Example:– The metacarpal of the
thumb
Inflammatory Disorders of the Joints
• Bursitis: inflammation of bursa (synovial membrane); water on the knee
Inflammatory Disorders of the Joints
• Sprain– Ligaments or tendons reinforcing joint are
damaged by excessive stretching or are torn away from bone
– Slow to heal because of poor blood supply• Dislocation– When a bone is forced out of normal position in
the joint cavity
Inflammatory Disorders of the Joints
• Arthritis– Most widespread, crippling disease in the U.S.– 1 in 7 Americans suffer with it– Initial symptoms: Pain, stiffness, and swelling of
the joint– Acute and Chronic forms of Arthritis
Inflammatory Disorders of the Joints
• Acute Arthritis– Result from bacterial invasion– Treated with antibiotic– Synovial membrane thickens and fluid production
decreases, leading to increased friction and pain
Inflammatory Disorders of the Joints
• Chronic Arthritis – Osteoarthritis
• Most common form• Degenerative condition, usually affects the aged• Wear and tear affects• Can cause bone spurs which restrict joint movement
– Rheumatoid arthritis• Occurs between 40-50 years of, but can occur at any age• Affects more women than men• Many joints affected at the same time and usually in symmetrical manner
(left elbow then right elbow)• Marked by remission (goes away) and flare ups (comes back)• Autoimmune disease – body attacks its own tissues
– Gouty arthritis