The Skeletal System - HBS

Functions _________________ Bones are the body’s supporting framework. Your bones give you shape and structure Your bones have to support the tissue that you have on your body.

Protection Bones protect our delicate _____________ including the brain, heart, and lungs.

Movement Bones need muscles for ________ ___ _____________. Muscles contract and relax to cause movement of the body.

Storage Bones store ____________________ Calcium is needed for nerve impulses to cause muscle movement.

The last function….. Hematopoiesis The process of ____________________ within the bone.

Number of Bones We have 350 bones at birth Why? Adults have 206

Types of Bones ________ We have four different types of bones found throughout the body ________

Long Short Flat Irregular

Divisions of the Skeletal System Axial Skeleton Vs Appendicular – color your picture

Bone Is a Living Tissue Bones need a blood supply, nutrients, and __________ There are also nerves that run through bones as well.

Microscopic Structures of Bone Bone can be divided into how it is constructed ________________________ Both types are found throughout the body and have very specific functions

Spongy Bone Compact Bone

Spongy Bone Contains many spaces that may be filled with bone marrow. The areas of spongy bone can be found at the ________________. These areas are where hematopoiesis occurs.

Compact (dense) Bone Does not contain a network of open spaces. It is used for ________, structure and support Yet it is still light so that we can move our bodies without extra weight

Structures of Long Bones Long bones include Humerus Ulna Radius Femur Tibia Fibula

Diaphysis The ______________ of the bones. It is _____________ but made of hard, compact bone. It is strong in structure Gives bone their “strength”

Epiphyses The _________________ of the bones Composed of spongy bone and red bone marrow.

Medullary Cavity The ________ ________within the bone Contains yellow bone marrow Soft and fatty form of bone marrow.

Articular Cartilage A thin layer of cartilage covering each epiphysis. Functions as a _________________________________.

Periosteum and Endosteum __________________- a fibrous membrane covering the long bone except at the joint surfaces. _________________- a thin membrane that lines the medullary cavity.

Compact (dense) Bone Does not contain a network of open spaces. Bone tissue is composed of repeating, circular units called ___________________. These circular systems are called _______ as well. Within each Haversian system, there is a central canal where blood vessels and nerves can be found.

The osteon or Haversian systems is composed of layers of a calcified matrix of circles called __________.

The darkly-stained spots are spaces called ___________. The lacunae contain _____________ which are bone cells.

____________________ connect multiple lacunae for nutrients to pass.

Nutrients pass from blood vessel in ________________ canal through the canaliculi to the osteocytes.

Osteoblasts Bone ____________ cells. Synthesize and secrete collagen fibers and other organic components of bone matrix. Initiate the process of calcification. Found in both the periosteum and the endosteum

The blue arrows indicate the osteoblasts The blue arrows indicate the osteoblasts. The yellow arrows indicate the bone matrix they’ve just secreted.

Osteoclasts Cells that _________________________– this process is called bone resorption and is part of normal bone growth, development, maintenance, and repair. Concentrated in the endosteum. The osteoclast secretes digestive enzymes to digest the bone matrix. It also pumps out hydrogen ions to create an acid environment that eats away at the matrix. Why do we want a cell that eats away at bone? (Hint: bone is a very dynamic tissue.)

Osteocytes Mature Bone Cells. Osteoblasts that have become trapped by the secretion of matrix. No longer secrete matrix. Responsible for _________________ ________________. Yellow arrows indicate osteocytes – notice how they are surrounded by the pinkish bone matrix. Blue arrow shows an osteoblast in the process of becoming an osteocyte. On the right, notice how the osteocyte is “trapped” within the pink matrix

Here, we see a cartoon showing all 3 cell types Here, we see a cartoon showing all 3 cell types. Osteoblasts and osteoclasts are indicated. Note the size of the osteoclast (compare it to the osteoblast). What is the name of the third cell type shown here? What do you think the tan material represents?