Download Ch. 14 Sec. 3 Notes

Ch. 14 Sec. 3 Notes
The Muscular System
*There are about 600 muscles in your body
Types of Muscles
*Some of your muscles are not under your conscious control
Ex: beating of your heart
*These muscles are called involuntary muscles
-Responsible for essential activities like breathing and digesting food
*The muscles that you can control are voluntary muscles
Ex: smiling, picking up a book, standing out of your chair
*Your body has 3 types of muscle tissue:
1. Skeletal muscle
2. Smooth muscle
3. Cardiac muscle
Skeletal Muscle
*Every time you walk across a room, you are using skeletal muscles
-Attached to the bones of your skeleton and provide force that moves your
bones
*At each end of a skeletal muscle is a tendon
-Strong connective tissue that attaches muscle to bone
*Because you have conscious control of your skeletal muscles, they are classified
as voluntary muscles
*Skeletal muscles can react very quickly, but tire quickly
Ex: Runners can go from a jog to a sprint, but without proper training they
will tire very easily
Smooth Muscle
*The inside of many internal organs, such as the stomach and blood vessels, contain
smooth muscles
*Involuntary muscles
*They work automatically to control certain movements inside your body, such as
digestion
*React slowly and tire slowly
Cardiac Muscle
*Muscles are found in your heart
*Involuntary
*Can react fast or slow, but never tires
*It contracts repeatedly, called heartbeats
Muscles at Work
*Skeletal muscles show their work by contracting, becoming shorter and thicker
*Muscle cells contract when they receive messages from the nervous system
*Skeletal muscles can only contract and not extend. Muscles must work in
pairs. While one contracts, the other relaxes to its original length.
Muscles Work in Pairs
*Biceps and Triceps work as pairs
*By flexing your biceps, your triceps relax
*By flexing your triceps, your biceps relax
Muscular Strength and Flexibility
*Regular exercise is important for maintaining both muscular strength and
flexibility
*Exercise makes individual muscles grow in size. As a result, the whole muscle gets
bigger
*Warming up increases blood flow through the body, which makes you more flexible
*Sometimes muscles can become injured
-You can pull or strain a muscle by overextending it or overworking it
-Tendons can be torn
-Skeletal muscles can cramp, which contracts the muscle hard and stays
contracted