The Difference Between Striated and Smooth Muscle

My physiology teacher came into class one day carrying three bags, from which he removed three sandwiches that he placed on the lab table at the front of the room. “Today, I’m going to demonstrate the differences between the three major muscle groups found in animals,” he said as he unwrapped a mouthwatering hamburger. “The most common muscles are striated or skeletal muscles.” He took a big bite out of the cheeseburger, wiped his dripping chin with a paper napkin and, around the mouthful of food, said, “One thing I can tell you is… skeletal muscle is mighty tasty.”

He then unwrapped the other two sandwiches, which didn’t look nearly as appetizing. “This,” he said, holding up the first, which contained some very bloody looking meat that didn’t look quite right, “is cardiac muscle. Can anyone tell us where cardiac muscle is found in the body?”

Nearly every hand shot up above all the eager faces, desperate to gain the professor’s favor by giving him the correct answer. As I knew about this particular teacher’s reputation, I kept my hand down and tried to shrink behind my desk as much as possible.

After carefully studying the enthusiastic students in the first couple of rows, he pointed at the worst suck-up in the class and said, “You.”

The guy stood up and proudly answered, “It’s found in the heart!”

Nodding, the professor spat out little bits of bun and mustard-drenched meat as he said, “That’s right.  Now come up and claim your reward.”

Looking very confused, the student went to the front of the class and accepted the sandwich held out to him. Looking down at the unsavory treat, he asked, “Is this what I think it is?”

“Yep,” said the teacher. “And that heart sandwich is all yours.”

The student took his seat and spent the rest of the class session holding onto the sandwich so it wouldn’t drip on his desk.

Then the professor picked up the second sandwich and asked, “Now, can anyone tell me where we might find smooth muscle?”

I knew the answer, but wasn’t about to give it up. Apparently, the rest of the class had wised up as well, for not one person raised their hand.

We had all taken biology before enrolling in physiology; we all knew that smooth muscle is found around blood vessels and hollow organs such as the digestive tract.

Smiling around another bite of his hamburger, the teacher said, “I guess no one here likes tripe,” and tossed the sandwich overflowing with pale, glossy tissue into the trash.

Besides the taste, the biggest difference between the two is that striated muscles—those that attach to bones—are voluntary (which means we have conscious control over them… usually) and smooth muscles are involuntary (they do their own thing without any encouragement from our conscious minds). Smooth muscles constrict in waves to push blood through veins and to a lesser degree through arteries; these muscles are also responsible for the peristaltic actions of the intestines, pushing something even less pleasant than blood through the GI tract to its ultimate destination. However, these distinctions are somewhat indistinct at times. For instance, through meditation or biofeedback, many people can control the actions of smooth muscles to a degree, thus lowering blood pressure or curing headaches by consciously willing the smooth muscles around the blood vessels to dilate slightly. And if you’ve ever experienced an involuntary muscle spasm—or worse yet, a cramp; God how I loathe them!—you know that skeletal muscles sometimes seem to have a mind of their own and do whatever they want beyond our control.