Download Integrated Science Chapter 15 Notes Section 1: Bones, Joints, and

Integrated Science
Chapter 15 Notes
Section 1: Bones, Joints, and Muscles
1. Bones and Joints
• Bones are made of living cells
• Main functions of bones
⇒ Allow movement
⇒ Support the body
⇒ Protect internal organs
• Joint – a place where two of more bones meet
⇒ Fixed joint – joints cannot move (ex.: between the bones of the skull)
⇒ Semi-movable joints – joints that allow little motion (ex.: between the bones of the spine)
⇒ Movable joints – joints that allow a lot of movement (ex.: between the bones in the elbow)
• Ligaments – a strong strap of tissue that holds the bones of a joint in place
• There are five kinds of movable joints:
⇒ Ball-and-socket – the hip and shoulder joints
⇒ Pivot - the elbow and joint between the top two vertebrae in the spine
⇒ Saddle – the base of the thumb
⇒ Gliding – the joints between the small bones in feet
⇒ Hinge – the knee
2. Muscles and Force
• Bones cannot move by themselves, they need skeletal muscles that contract and do work
• Force is transmitted from skeletal muscles to bone through string cords of tissue called tendons
⇒ Tendon – a strong cord of tissue that connects a skeletal muscle to a bone
• Muscles move by tightening in response to nerve signals
• Pairs of muscles move in opposite directions
• Pairs of opposing muscles exist around some of the joints in the body
⇒ Flexor – a muscle that decreases the angle between two bones
⇒ Extensor – a muscle that increases the angle between two bones
⇒ Flexors and extensors act in coordinated way, when contacts the other relaxes
• Two other types of muscle
⇒ Cardiac muscle – the muscle of the heart
⇒ Smooth muscle – found in the walls of many hollow internal organs (the stomach and the
large and small intestines)
⇒ These muscles do not require signals from the brain to work
3. Disorders of the Bones, Joints, and Muscles
• Osteoporosis – a disorder in which the bones become less dense and more fragile
• Arthritis – a condition in which the joints become swollen and painful
Section 2: Exercise and Physical Fitness
1. Physical fitness – the ability to carry out moderate physical tasks without becoming tired
2. Anaerobic Exercise
• The body obtains energy by reacting the carbohydrates, fats, and proteins in food with oxygen
• The oxygen reactions are slow, and sometimes you need energy for bursts of activity
• Anaerobic exercise – an exercise that is powered by energy releasing reactions that do not
require oxygen
⇒ Anaerobic exercise increases skeletal muscle size and strength
⇒ Anaerobic exercise leads to muscle fatigue and an oxygen debt
⇒ Muscle fatigue – the loss of muscle strength due to prolonged exercise
⇒ Oxygen debt – the extra amount of oxygen needed to return muscles to their normal
condition after anaerobic exercise
3. Aerobic Exercise
• Aerobic exercise – an exercise that is powered by energy releasing reactions that require
oxygen
• Aerobic exercise strengthens the heart and increases endurance
• Endurance – the ability to continue exercising before becoming completely exhausted
4. Using Exercise
• Exercise makes muscles stronger and improves the condition of the body
• Exercise makes the ligaments that hold your bones together more elastic
⇒ Flexibility – the ability of the body to move at its joints
Section 3 Spaceflight and Fitness
1. Effects of Spaceflight on Bones and Muscles
• Bones become weaker during spaceflight
• Muscles shrink and undergo other changes during spaceflight
⇒ Atrophy – the decrease in the size of a body structure due to disease, aging, or lack of use
• Exercise can prevent some bone and muscle changes
2. Other effects of spaceflight
• With no sense of up or down, astronauts become disoriented
• Spaceflight has impact on physical coordination
• Blood is redistributed during spaceflight
• Spaceflight causes changes in blood volume and red blood cell counts
⇒ Anemia – a condition in which the blood contains fewer red blood cells than normal