Muscle Day 3 Twitches

Do now Read pages 187-189, section 8.4 Write the vocabulary that is in bold on a paper to turn in after you have defined each word

Vocabulary threshold stimulus twitch latent period summation titanic contraction recruitment muscle tone

Objectives Distinguish between a twitch and a sustained contraction. Explain how muscular contractions move body parts and help maintain posture.

Essential Question How do stimuli contract muscle fibers to move the body? How do muscles contract to permit precise control of pressure and movement?

Why do muscles burn after extended activity Why do muscles burn after extended activity? What process does this signify?

Threshold stimulus The threshold stimulus is the stimulus required to create an action potential. So any stimulus under this level will not cause muscle contraction, while a stimulus above this level will cause the muscle to contract. The higher the stimulus the more muscle fibers are recruited, and thus the higher the response.

Slow and fast muscle twitches Most of your muscles are made up of a mixture of both slow and fast twitch muscle fibers. But, your soleus muscle in your lower leg and muscles in your back involved in maintaining posture contain mainly slow twitch muscle fibers. And muscles that move your eyes are made up of fast twitch muscle fibers.

Motor units Muscles are organized into many motor units controlled by a single motor neuron. A nerve impulse to that unit will contract all the muscle fibers of that unit at the same time. At higher intensities of stimulation recruitment of motor units occurs until the muscle contracts with maximal tensions.

Sustained Contractions When muscles are at rest, its fibers undergo some sustained contraction. We call this muscle tone and it is important because it helps in maintaining posture. When muscle tone is lost the body will collapse.

Origin and Insertion Bones forming moveable joints function as levers. One end of a skeletal muscle usually fastens to a relatively immoveable or fixed part at a moveable joint, and the other end connects to a moveable part on the other side of that joint.

When a muscle contracts, its insertion is pulled toward its origin The immoveable end of the muscle The moveable end of a joint

Use the following words the label the muscle worksheets Rectus Femoris Gastrocnemius Trapezius Rectus Abdominus Gluteus Maximus Triceps Brachii Deltoid Semimembranosus Pectoralis Major Biceps femoris Tibialis Anterior Vastus Medialis External Oblique Latissimus Dorsi Vastus Lateralis Semitendinosus Biceps Brachii Soleus

Frontalis Temporalis Orbicularis oculi Zygomaticus Masseter Orbicularis Oris Buccinator Trapezius Sternocleidomastoid

Exit map of different types of exercise or lack of exercise and their effects on the body, focusing on difference between strength and stamina training.