The Skeletal System Chapter 5

Chapter Overview Functions of Bone Two kinds of bone tissue – compact and spongy – types of marrow Development of bone – cartilage model Hormones and bone growth Importance of Bone Remodeling; osteoblasts and osteoclasts Loss of bone density – Osteoporosis Ligaments and tendons Overview of Human Skeleton – Axial and Appendicular –KNOW THE NAMES and LOCATIONS OF ALL THE BONES AXIAL: Skull, ribs, sternum, vertebral column, intervertebral disks APPENDICULAR: Pectoral girdle -scapula, clavicle, upper limb bones, pelvic girdle, leg, ankle and foot bones Joints – types of joints and MOVEMENTS at joints – learn all terms Diseases/disorders –osteoarthritis, rheumatoid arthritis, sprain, bursitis, dislocations, types of fractures, scoliosis, herniated discs Role of fibroblasts and osteoblasts in repairing bone fractures

Bone Functions The skeleton is a framework of bones and cartilage that performs several functions Support for soft tissues Provides a place of attachment for muscles Protects internal organs Stores minerals (calcium and phosphorus) and fat Certain bones produce blood cells in the red marrow

There Are Two Kinds of Bone Tissue Compact bone Dense tissue Periosteum – membrane that nourishes the bone Forms in thin, circular layers around central canals -Osteon Bone shaft and outer part of the two ends Spongy bone Inside long bone’s shaft Looks lacy; quite strong

Figure 5.1 The structure of bone. 6

Bone Marrow Connective tissue where blood cells are formed Red marrow Occurs in spongy bone of some bones (ribs, pelvis, backbone, skull, sternum and long bone ends) Produces blood cells Yellow marrow Fills the cavities of adult long bones Is largely fat and used for energy storage

Figure 5.2 The fetal skeleton is first made of cartilage and gradually is replaced by bone. 9

Figure 5.3 Steps of bone formation in long and short bones, from an embryo into childhood. 10

Cartilage Model Web Activity: Bone Growth 11

Tuesday, 10/31/17 What are the 5 steps/stages of bone formation? Do Not look in book or notes…….. Discuss with the person next to you

5 steps of bone formation Cartilage model Bone collar formation (osteoblasts) around the shaft of the model Shaft hollows out, spongy bone fills in; blood vessels penetrate so bone formation expands Bone formation develop in the ends of bone (secondary centers) Cartilage remains only on contact surfaces and growth plate

Hormones and Bone Growth Growth hormone stimulates bone growth during childhood Thyroid hormones ensure that the skeleton grows with the proper proportions Sex hormones (testosterone and estrogen) prompt and stop the growth spurt of puberty

Hormones and Bone Growth By the end of the teenage years, sex hormones initiate less frequent cell division Growth plate thins Ends of the bone fuse with the shaft Bone can no longer increase in length

Stop and Think! We have discussed the mechanism by which long bones grow and the role of growth hormone in that process. Why would it be ineffective for a short, middle-aged person to be treated with growth hormone to stimulate growth? Discuss with person next to you.

Bone Remodeling – Osteoblasts and Osteoclasts Osteoblasts form/deposit/build bone Osteoclasts BREAK DOWN bone -secrete enzymes that degrade it – release calcium and other minerals that are reabsorbed by the body In adults, bone building and bone breakdown continue constantly Calcium is constantly entering and leaving a person’s bones

Bone Tissue Is Constantly “Remodeled” The ongoing calcium recycling is called BONE REMODELING Keeps bones resilient Mechanical stress Repair of broken bones During growth Homeostasis of blood calcium levels (interplay of two hormones calcitonin and parathyroid hormone PTH)

Monday, 11/6/17 What are the steps of healing in a bone? Complete the worksheet by numbering the steps in the order that healing takes place. Give a brief description of what is taking place for each step.

Healing Bone Activity PDF

The Role of Fibroblasts and Osteoblasts in Repairing Bone Fractures Nondisplaced fracture: the ends remain aligned Displaced fracture: the ends must be realigned When a bone breaks, bleeding occurs and a clot forms Fibroblasts invade the clot and secrete collagen fibers that form a callus linking the two parts of the bone Osteoblasts transform this cartilage into bone

The Role of Fibroblasts and Osteoblasts in Repairing Bone Fractures Web Activity: Bone Repair 25

Bone Tissue Is Constantly “Remodeled” The ongoing calcium recycling is called BONE REMODELING Keeps bones resilient Mechanical stress Repair of broken bones During growth Homeostasis of blood calcium levels (interplay of two hormones calcitonin and parathyroid hormone PTH)

Bone remodeling - the process of bone deposition and breakdown * also helps regulate blood calcium levels * calcium plays a role in the functioning of nerves and muscles as well as blood clotting Calcitonin and Parathyroid Hormone – help control bone remodeling and regulat- ing blood calcium levels.

Bone Density As we age, bone tissue may break down faster than it is renewed Osteoporosis is a progressive deterioration in bone density May occur when the action of osteoclasts outpaces that of osteoblasts May also occur as a result of inability to absorb calcium Calcium and sex hormone deficiency, smoking and a sedentary lifestyle – contribute to osteoporosis Exercise, dietary calcium and drugs may slow it down

In Osteoporosis, Bone Tissue Breaks Down Faster Than It Is Rebuilt http://www.youtube.com/watch?v=rHyeZhcoZcQ

Exit Question Contrast the functions of osteocytes, osteoblasts and osteoclasts.

Tuesday 11/7/17 How does calcitonin and parathyroid hormone (PTH) control bone remodeling and blood calcium levels?

Bones, Ligaments, and Tendons Are the Basic Components of the Skeleton Organization of human’s 206 bones Axial skeleton Appendicular skeleton Ligaments (elastic connective tissue – stretchy and resilient) Connect bones at joints Tendons – cords/straps of connective tissue packed with collagen fibers Attach muscles to bones or other muscles

Figure 5. 6 Major bones of the human body Figure 5.6 Major bones of the human body. Bones of the axial skeleton are shown in orange; bones of the appendicular skeleton are shown in light brown. Cartilage is shown in light purple. 35

Axial Skeleton The axial skeleton: protects and supports our internal organs Components Skull Vertebral column Sternum and rib cage

Facial bones (fourteen bones) Support several sensory structures Figure 5.7 Major bones of the skull and face. Facial bones (fourteen bones) Support several sensory structures Serve as attachment sites for most facial muscles 37

Cranial Bones The cranium which is formed from eight (sometimes more) flat bones Protect the brain House the structures of hearing Provide attachment sites for the muscles of the head and neck

Figure 5.8 The skull bones of a human newborn are not fused but are instead connected by fibrous connective tissue. Before and shortly after birth, the bones of the cranium are connected by membranous areas called fontanels Allow the skull to be compressed during birth as the baby passes through the birth canal Allow for the rapid growth of the brain during the fetal period and infancy Replaced by bone by 2 years of age 42

Vertebral Column The vertebral column consists of 26 vertebrae 7 cervical (neck) vertebrae (C1–C7) 12 thoracic (chest) vertebrae (T1–T12) 5 lumbar (lower back) vertebrae (L1–L5) 1 sacrum (formed by the fusion of five sacral vertebrae) 1 coccyx (or tailbone, formed by fusion of four vertebrae)

Wednesday 11/8/17 Which bones form the bridge of the nose? Which bones form the cheekbones in the skull? What are the interconnected bones that form the backbone?

Intervertebral disks separate vertebrae from one another Figure 5.9 A side view of the vertebral column. Intervertebral disks separate vertebrae from one another Pads of fibrocartilage Become compressed over the years and individuals become shorter as they age 46

Label the skeleton

Vertebral Column and Scoliosis “Twisted disease” Abnormal curvature of the spine Cause is unknown Affects over 1.5 million adolescents, primarily females Treatment may involve a brace or surgery

Vertebral Column and Intervertebral Disks The term “slipped disk” is a misnomer It is a disk that bulges but does not move out of place If a disk bulges inward, it can press against the spinal cord and interfere with perception of incoming stimuli and muscle control If a disk bulges outward, it can press against the sciatic nerve and cause the painful inflammatory condition sciatica

Rib cage 12 pairs of ribs attach at the back of the rib cage to the thoracic vertebrae Upper 10 pairs are attached by cartilage either directly or indirectly to the sternum Last two pairs do not attach to the sternum and are called “floating ribs”

Label the skeleton

Appendicular Skeleton The appendicular skeleton allows movement and interaction with the environment Components Pectoral girdle Pelvic girdle Limbs

Composed of: Function: Scapulae Clavicles Supports the arms Figure 5.11 The pectoral girdle and arm. Composed of: Scapulae Clavicles Function: Supports the arms 53

More rigid than the pectoral girdle Figure 5.12 The pelvic girdle and leg. More rigid than the pectoral girdle Composed of: Two pelvic bones joined in front at the pubic symphysis Function: Supports the legs 54

Label the skeleton

5.5 Joints: Connections between Bones Joints are areas of contact or near contact between bones All joints have some form of connective tissue that bridges the gap between bones

Types of Joints Synovial joint (knee, elbow, hips) Synovial fluid Movement Cartilaginous joint (vertebrae) Slight movement Fibrous joint (teeth-socket) No cavity Generally no movement

Figure 5.13 The knee is a synovial joint. 58

Synovial Joints Synovial joints differ in the type and range of motion they permit Hinge joints Motion in only one plane Example: knee Ball-and-socket joints Motion in all planes Example: shoulder

Figure 5.14 Types of movement at synovial joints. 60

Thursday 11/9/17 Name the three types of joints Do they have movement? Where do you find them? The pectoral girdle is composed of what bones? The pelvic girdle is composed of what bones?

Carpal tunnel syndrome

Damage to Joints Sprains Bursitis Injuries to ligaments Range from slight (caused by overstretching) to serious (caused by tearing) Example: tearing the anterior cruciate ligament of the knee Bursitis Inflammation of the bursae (fluid-filled sacs that surround and cushion joints) Example: inflammation at the elbow from repeatedly swinging a tennis racket

Arthritis Joint inflammation Types Osteoarthritis Degeneration of joint surfaces over time Rheumatoid Autoimmune condition marked by an inflammation of the synovial membrane Damaged joint may need to be replaced with an artificial joint

Rheumatoid Arthritis May Cause Bones to Become Misaligned

Friday 11/10/17 Skeletal Lab Scavenger Hunt

Chapter Review Functions of Bone Two kinds of bone tissue – compact and spongy – types of marrow Development of bone – cartilage model Hormones and bone growth Importance of Bone Remodeling; osteoblasts and osteoclasts Loss of bone density – Osteoporosis Ligaments and tendons Overview of Human Skeleton – Axial and Appendicular –KNOW THE NAMES and LOCATIONS OF ALL THE BONES AXIAL: Skull, ribs, sternum, vertebral column, intervertebral disks APPENDICULAR: Pectoral girdle -scapula, clavicle, upper limb bones, pelvic girdle, leg, ankle and foot bones Joints – types of joints and MOVEMENTS at joints – learn all terms Diseases/disorders –osteoarthritis, rheumatoid arthritis, sprain, bursitis, dislocations, types of fractures, scoliosis, herniated discs Role of fibroblasts and osteoblasts in repairing bone fractures