Do Now Quick experiment: In one jar is an egg covered by water and in the other jar an egg covered with vinegar. Briefly do the following: 1. What is the purpose? 2. What are the materials used? 3. What do you think will happen and why? This is the hypothesis What do we know about vinegar? Where does it sit on the PH Scale?

Homework due today Homework 1.Read pages 930 – 934. a.Be prepared to discuss the article on page 934 (Steroids) 2.Given the length of the quiz and the fact that so many did not finish the Pre-Lab Write up. a. Pre-lab report? b. Steroids article

Homework Homework - Re-read / summarize if necessary 1.Read pages 930 – 934. a.Be ready show your notes from the reading assignment b.Be prepared to discuss the article on page 934 (Steroids) 2.For Tuesday – Each of you will have a topic to begin to research and present (written and presentation form). Use the attached sheet to begin to develop your topic.

Are we ready for the lab? Are we ready? If so, then follow instructions and begin to do the lab. Put on an apron, goggles and gloves. Re-read your instructions and then begin. If we are not ready then class-time.

Muscular System Muscles allow movement, but they also allow basic functions to occur. There are three types of muscle: 1. Cardiac – the muscle of the heart is very special. Never rests. 2. Smooth Muscle (aka involuntary muscle) – such as muscles around the rib cage. 3. Skeletal Muscle (aka voluntary muscle) – muscles that you decide to move or control.

Muscular System Skeletal muscles – eventually attach to bones. Skeletal muscle under a microscope will show striation caused by white and dark fibers. Why do chicken legs have dark meat? Darker generally means more blood travels through. More in the legs because the muscle is thicker and used for walking versus the breast which is more white meat.

Muscular System Smooth Muscle – little or no striation. Under the microscope the muscle appears smooth (hence the term). They are called involuntary because you do not have control over these muscles. Other muscles that are smooth – digestive Question – if you are paralyzed will these muscles still function? Depends where the cut to the spinal cord is. Sometimes the impulse will allow the muscle to still function. Skeletal will not

Muscular System Cardiac muscle – is somewhat a combination of smooth & skeletal. Smooth because the person has no control over them. Like skeletal because it is very strong and fibrous (striation). The heart can never stop beating or tire. It has its own impulse to beat known as a pacemaker. Some people have an external pace because their heart does not beat on its own.

Muscular Contraction What is a muscle contraction? It occurs in the body when movement is necessary. It is when muscle is shortened. Skeletal muscles are filled with bundles of filaments called myofibrils. Myo means muscle Each myofibril contains a layer of protein called myosin (thick layered) and a thin layer of protein called actin

Muscular Contraction These thick & thin layered fibers are weaved together or overlaid which produced what looks like stripes. The thin actin filaments are arranged in Z- lines. Two Z-lines and the filament between them form a sacromere

Muscular Contraction During a contraction, myosin filaments form a cross-bridge with the actin filaments. These cross bridges change shape and pull the actin filaments to the center of the sacromere. Then it detaches and then it repeats. As they slide the muscle shortens or contracts. The process is known as the sliding filament theory