Leaving Certificate Agricultural Science

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Leaving Certificate Agricultural Science
The Skeletal System
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Introduction

• The human skeleton is an endoskeleton of bone and
  cartilage.
• Major Functions  
• Support for the soft tissues and largely
  responsible for the shape of the human body.
• Movement the strong rigid bones function as
  levers moved by the contraction of muscles.
• Protection the tough bones protect delicate
  vital organs
• the brain is protected by the skull
• heart and lungs are protected by the rib cage
• spinal cord is protected by the backbone
• Axial Skeleton skull, backbone, ribs and
  sternum.

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Composition of Bone

• Bone is made of mineral compounds of Calcium that
  are strong yet brittle.
• Inside bone there is a network of cells, blood
  vessels and nerves.
• Large bones are hollow, the outside (matrix)
  being hard while the centre (marrow) soft and
  fatty and rich in blood and leucocytes.
• Smaller bones (like the ribs) are not hollow but
  have several smaller holes.
• In these holes there is red bone marrow, where
  red blood corpuscles are made.

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Regions of the Spine

• The Spine or Backbone is divided into different
  sections
• Cervical Vertebrae (Neck region)
• The Thoracic Vertebrae (Ribs area)
• The Lumbar Vertebrae (Lower back)
• The Sacrum (Sacral region)
• The Caudal region (The tail)
• Composed of 33 small bones in a line - cervical
  (7), thoracic (12), lumbar (5), sacrum (5),
  coccyx (4).
• The vertebrae of the sacrum and coccyx are fused.
  

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Joints

• A joint is the junction between two or more
  bones.
• There are three major types of joints.
• Fused Joints skull, sacrum, pelvis, and coccyx.
• Slightly Moveable between the vertebrae.
• Synovial freely moveable - the movement is
  lubricated by synovial fluid.

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Types of Synovial Joints

• Hinge movement in one plane during flexion and
  extension.
• Examples bending the elbow or knee.
• Ball and Socket permits movement in three
  planes, i.e., in all directions.
• Examples the shoulder and hip joints.
• Gliding the bones move across each other,
  back-and-forth and side-to-side.
• Examples between the carpals of the wrist and
  tarsals of the ankle.
• Pivot allows a turning movement.
• Examples between the first and second vertebras
  when turning the head, between the ulna and the
  radius of the lower arm when turning the palm of
  the hand up or down.

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Muscle

• Muscles are used for movement and are attached to
  bones via tendons.
• For effective movement there are two muscles
  connected to each limb.
• These muscles are said to be antagonistic
  muscles.
• This means that will one contracts, the other
  relaxes and vice versa.
• The biceps and triceps are examples of
  antagonistic muscles.
•  There are three types of muscle in the body
• Striated Muscle (Voluntary muscle attached to
  bones etc)
• Smooth Muscle (Involuntary muscle found in our
  stomachs and intestines)
• Cardiac Muscle (Involuntary muscle only found in
  the heart)

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Muscle 2

• Muscle is an extremely contractile connective
  tissue.
• There are a number of different types of muscle
  Skeletal, Cardiac and Smooth.
• The contraction of muscle performs four important
  functions
• Movement
• Posture maintenance
• Support the joints
• Heat production
• Skeletal muscle is connected to the skeleton by
  tendons.
• It is under conscious control.
• Its contraction is fast and strong.
• Skeletal muscle tires easily.

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