{"id":2411,"date":"2021-06-10T19:55:38","date_gmt":"2021-06-11T02:55:38","guid":{"rendered":"https:\/\/magoosh.com\/mcat\/?p=2411"},"modified":"2021-06-10T19:55:38","modified_gmt":"2021-06-11T02:55:38","slug":"muscular-system-mcat","status":"publish","type":"post","link":"https:\/\/magoosh.com\/mcat\/muscular-system-mcat\/","title":{"rendered":"Muscular System on the MCAT"},"content":{"rendered":"

\"Woman<\/p>\n

A big part of scoring well on the Biological and Biochemical Foundations of Living Systems section<\/a> is familiarizing yourself with muscular system MCAT content. Below, we’ll go over some key facts about skeletal muscles, smooth muscle contraction, and more. <\/p>\n

For a super handy PDF version of this material, and for more MCAT resources, click the link below!<\/p>\n

\"Click<\/a><\/p>\n

Organization of Skeletal Muscles <\/h2>\n

First and foremost, here’s a simple breakdown of how skeletal muscle is organized:<\/p>\n

\"Muscular<\/p>\n

You’ll also need to understand the difference between smooth muscle and skeletal muscle, which we’ve broken down for you here:<\/p>\n\n\n\n\n\n\n
<\/th>\nFunction<\/th>\nContraction <\/th>\nAppearance<\/th>\n<\/tr>\n<\/thead>\n
Smooth Muscle<\/td>\nSurround organs (except for the heart) and blood vessels<\/td>\nInvoluntary<\/td>\nNonstriated or tapered<\/td>\n<\/tr>\n
Skeletal Muscle<\/td>\nMoves the skeleton <\/td>\nVoluntary<\/td>\nStriated, multinucleated<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

<\/p>\n

Sarcomere MCAT Structure and the Sliding Filament Model<\/h2>\n

Understanding how muscles actually work is also key to success on the MCAT. Muscle contraction occurs when the motor protein, myosin, pulls on actin. The filaments move past one another, shortening the sarcomere and generating muscle tension. <\/p>\n

For reference, sarcomere<\/strong> is the smallest functional unit of muscle<\/strong>, visible as striations on muscle cells. <\/p>\n

The sliding filament model<\/strong>, as seen below, is used to represent this function in the muscular system. MCAT questions may pertain to any of the follow aspects of muscle contraction:<\/p>\n

\"Sliding<\/p>\n

Muscle Components<\/h2>\n

To better understand the above model, it helps to know the various components of muscle and how they help facilitate contraction:<\/p>\n\n\n\n\n\n\n\n\n\n\n\n
Component<\/th>\nDefinition <\/th>\nEffect on Contraction <\/th>\n<\/tr>\n<\/thead>\n
Thick filament<\/td>\nComposed of myosin<\/td>\nMyosin heads bind to actin<\/td>\n<\/tr>\n
Thin filament<\/td>\nComposed of actin<\/td>\nSlides past myosin<\/td>\n<\/tr>\n
Z-Line<\/td>\nMark the borders of the sarcomere. Site of connection for actin.<\/td>\nMoves closer together<\/td>\n<\/tr>\n
M-line<\/td>\nMidline of the sarcomere<\/td>\nNo change<\/td>\n<\/tr>\n
I Band<\/td>\nContains only<\/strong> thin filaments<\/td>\nShortens<\/td>\n<\/tr>\n
H Band<\/td>\nContains only<\/strong> thick filaments<\/td>\nShortens<\/td>\n<\/tr>\n
A Band<\/td>\nThe length of the thick filaments<\/td>\nNo change<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

<\/p>\n

And when trying to memorize the functions of each of the above muscle components, here is one of our favorite memorization tips<\/strong>:<\/p>\n