Scientists define matter as anything that occupies space and has mass. An object of a certain mass weighs less on the moon, for example, than it does on Earth because the gravity of the moon is less than that of Earth. In other words, weight is variable, and is influenced by gravity. A piece of cheese that weighs a pound on Earth weighs only a few ounces on the moon.
By the end of this section, you will be able to: Describe the different types of muscle Explain contractibility and extensibility Muscle is one of the four primary tissue types of the body, and the body contains three types of muscle tissue: All three muscle tissues have some properties in common; they all exhibit a quality called excitability as their plasma membranes can change their electrical states from polarized to depolarized and send an electrical wave called an action potential along the entire length of the membrane.
While the nervous system can influence the excitability of cardiac and smooth muscle to some degree, skeletal muscle completely depends on signaling from the nervous system to work properly.
On the other hand, both cardiac muscle and smooth muscle can respond to other stimuli, such as hormones and local stimuli.
A muscle can return to its original length when relaxed due to a quality of muscle tissue called elasticity. It can recoil back to its original length due to elastic fibers.
Muscle tissue also has the quality of extensibility; it can stretch or extend. Contractility allows muscle tissue to pull on its attachment points and shorten with force. Differences among the three muscle types include the microscopic organization of their contractile proteins—actin and myosin.
The actin and myosin proteins are arranged very regularly in the cytoplasm of individual muscle cells referred to as fibers in both skeletal muscle and cardiac muscle, which creates a pattern, or stripes, called striations. The striations are visible with a light microscope under high magnification see [link].
Skeletal muscle fibers are multinucleated structures that compose the skeletal muscle.
Cardiac muscle fibers each have one to two nuclei and are physically and electrically connected to each other so that the entire heart contracts as one unit called a syncytium.
Because the actin and myosin are not arranged in such regular fashion in smooth muscle, the cytoplasm of a smooth muscle fiber which has only a single nucleus has a uniform, nonstriated appearance resulting in the name smooth muscle. However, the less organized appearance of smooth muscle should not be interpreted as less efficient.
Smooth muscle in the walls of arteries is a critical component that regulates blood pressure necessary to push blood through the circulatory system; and smooth muscle in the skin, visceral organs, and internal passageways is essential for moving all materials through the body.
Chapter Review Muscle is the tissue in animals that allows for active movement of the body or materials within the body. There are three types of muscle tissue: Cardiac muscle is found in the wall of the heart and pumps blood through the circulatory system. Smooth muscle is found in the skin, where it is associated with hair follicles; it also is found in the walls of internal organs, blood vessels, and internal passageways, where it assists in moving materials.The Five Major Compounds That Make Up the Human Body The human body is one of the most complex and fascinating things on this planet.
There are five major groups of compounds that compose the human body. An Overview of the Defense of Frankenfoods, the Genetically Engineered Farm Products. words. 2 pages. An Overview of the Compounds That Compose the Human Body. 1, words. 2 pages. An Analysis of the Biological Warfare at Disposal of the United States.
1, words. An Introduction to the Human Body. 1. Introduction 2. 63 Overview of Muscle Tissues Learning Objectives. By the end of this section, you will be able to: Describe the different types of muscle; Skeletal muscle fibers are multinucleated structures that compose the skeletal muscle.
Organic compounds, which are the compounds associated with life processes, are the subject matter of organic chemistry. Among the numerous types of organic compounds, four major categories are found in all living things: carbohydrates, lipids, proteins, and nucleic acids.
The Five Major Compounds That Make Up the Human Body The human body is one of the most complex and fascinating things on this planet. There are five major groups of compounds that compose .
The human body is composed of elements, the most abundant of which are oxygen (O), carbon (C), hydrogen (H) and nitrogen (N). You obtain these elements from the foods you eat and the air you breathe.
The smallest unit of an element that retains all of the properties of that element is an atom.