Human Biology and health

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Human Biology and health
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• The levels of organization in the human body
  consist of cells, tissues, organs, and organ
  systems. A cell is the basic unit of structure
  and function in a living thing. Cells perform the
  basic processes that keep organisms alive. Most
  cells are too small to see without a microscope.
  In most animal cells, a cell membrane forms the
  outside boundary of the cell. Inside the cell
  membrane is a large structure called the nucleus.
  The nucleus is the control center that directs
  the cells activities and contains information
  that determines the cells characteristics. The
  area between the cell membrane and the nucleus is
  called the cytoplasm

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• A tissue is a group of similar cells that perform
  the same function. The human body contains four
  basic types of tissue muscle tissue, nerve
  tissue, connective tissue, and epithelial tissue.
  Muscle tissue can contract, or shorten. This
  tissue is what makes parts of your body move.
  Nervous tissue carries messages back and forth
  between the brain and every other part of the
  body. It directs and controls the body.
  Connective tissue provides support for your body
  and connects all its parts. Bone, fat, and blood
  ar e all connective tissues. Epithelial tissue
  covers the surfaces of your body. The skin and
  the lining of the digestive system are examples
  of epithelial tissue.

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• An organ is a structure that is composed of
  different kinds of tissue. Like a tissue, an
  organ performs a specific job. An organs job is
  usually more complex than that of a tissue. The
  heart is an organ that pumps blood throughout the
  body.
• Each organ in your body is part of an organ
  system. An organ system is a group of organs that
  work together to perform a major function. Your
  heart is part of an organ system called the
  circulatory system. The blood vessels are also
  part of the circulatory system. The different
  organ systems work together and depend on one
  another.

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• All the systems of the body work together to
  maintain homeostasis, the bodys tendency to keep
  an internal balance. Homeostasis is the process
  by which an organisms internal environment is
  kept stable in spite of changes in the external
  environment. Sometimes, things can happen to
  throw off homeostasis. As a result, your heart
  may beat more rapidly or your breathing may
  quicken. These are signs of stress, the reaction
  of your body to potentially threatening,
  challenging, or disturbing events. When the
  stress is over, homeostasis is restored, and the
  body returns to its normal state.

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• The Skeletal System
• Guide for Reading
• What are the functions of the skeleton?
• What role do joints play in the body?
•   What are the characteristics of bone, and
  how can you keep your bones strong and healthy?

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What the Skeletal System Does
- The Skeletal System

• Your skeleton has five major functions. It
  provides shape and support, enables you to move,
  protects your organs, produces blood cells, and
  stores minerals and other materials until your
  body needs them.

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• The Skeletal System
• The skeleton is made up of all the bones in ones
  body. Your skeleton has five major functions. It
  provides shape and support, enables you to move,
  protects your organs, produces blood cells, and
  stores minerals and other materials until your
  body needs them. The backbone, or vertebral
  column, is the center of the skeleton. The
  backbone is made up of 26 small bones, or
  vertebrae (singular vertebra). If your backbone
  were just one bone, you would not be able to bend
  or twist.

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Joints of the Skeleton
- The Skeletal System

• A joint is a place in the body where two bones
  come together. Joints allow bones to move in
  different ways.

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• The Skeletal System
• A joint is a place in the body where two bones
  come together. Joints allow bones to move in
  different ways. Immovable joints connect bones in
  a way that allows little or no movement. Movable
  joints allow the body to make a wide range of
  movements. The bones in movable joints are held
  together by a strong connective tissue called a
  ligament. Cartilage is a connective tissue that
  is more flexible than bone

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• The Skeletal System
• Bones are complex living structures that undergo
  growth and development. A thin, tough membrane
  covers all of a bone except the ends. Blood
  vessels and nerves enter and leave the bone
  through the membrane. Beneath the membrane is a
  layer of compact bone, which is hard and dense,
  but not solid.

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• The Skeletal System
• Small canals run through the compact bone,
  carrying blood vessels and nerves from the bones
  surface to the living cells within the bone. Just
  inside the compact bone is a layer of spongy
  bone, which has many small spaces within it.
  Spongy bone is also found at the ends of the
  bone. The spaces in bone contain a soft
  connective tissue called marrow. There are two
  types of marrowred and yellow. Red bone marrow
  produces blood cells. Yellow marrow stores fat
  that serves as an energy reserve.

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• The Skeletal System
• A combination of a balanced diet and regular
  exercise are important for a lifetime of healthy
  bones. As people become older, their bones begin
  to lose some minerals. Mineral loss can lead to
  osteoporosis, a condition in which the bodys
  bones become weak and break easily. Regular
  exercise and a diet rich in calcium can help
  prevent osteoporosis.

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BonesStrong and Living
- The Skeletal System

• Bones are complex living structures that undergo
  growth and development.

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Asking Questions
- The Skeletal System

• Before you read, preview the red headings. In a
  graphic organizer like the one below, ask a what
  or how question for each heading. As you read,
  write answers to your questions.

Question
Answer
What does the skeleton do?
The skeleton provides shape and support, helps
you to move, protects organs, produces blood
cells, and stores minerals and other materials.
Joints can move forward or backward, in a circle,
in a rotating motion, and in a gliding motion.
How do joints move?
How strong are bones?
Bones can absorb more force without breaking than
granite or concrete.
What can I do to care for my bones?
Eat a well balanced diet and get plenty of
exercise.