Differentiate between types of muscle tissues
Without the 3 types of muscle tissues we would not be able to physically move from point a to point b, digest food, breath, or live. Muscle tissue functions by contracting and applying contractile forces to various parts of the body. With that in mind, let us look at the diverse types of muscle cells in the human system. Each of these tissues has specialized cells that give it its own unique properties.
There are 3 types of muscle tissue – cardiac, smooth, and skeletal muscle.
1. Skeletal Muscle
This type of muscle is attached to the bones of our skeletal framework. When our muscles contract, the contraction allows us to ambulate(movement), make facial expressions, and sit upright(posture). Skeletal muscle makes up about 40% of body mass. Some of the skeletal muscles that it gives rise to are some we are familiar with such as, quadriceps, triceps, those found in the eyes, anus, throat, and diaphragm just to name a few. There are 4 characteristics that make skeletal muscles unique. Skeletal muscle cells are voluntary, striated, not branched, and multinucleated. This tissue is the only muscle tissue out of the 3 that are voluntary in nature, meaning that they are under our conscious control, we can will them to move. Skeletal muscle completely depends on signaling from the nervous system to work properly. This muscle type also fatigues easily (think about when you exercise).
Functional properties of skeletal muscle
There are 3 functional properties of skeletal muscles, and they are, movement, heat production, and maintaining posture.
Happens when muscles that are attached to the bones are stimulated, by a contraction (via the somatic nervous system) that causes one to move that appendage(part)of that body. This part of the nervous system influences conscious, will full voluntary movement.
Maintains posture in conjunction with the nervous system that sends sensory information about the position of body parts. By doing this, it enables posture to be maintained.
• Heat production
Yes, muscle produces heat! About 70% of body heat arises from our muscle tissue. For example, when you are cold, you shiver. Your muscles sense through thermoreceptors in your skin that there is a change in temp. A message is relayed to the brain, and the instructions that the muscles are given is to start moving by generating heat by contracting and relaxing involuntarily to active heat and maintain homeostasis with body temp.
2. Cardiac Muscle
Cardiac muscle tissue is composed of highly specialized tissue found only in the heart. It is responsible for pumping and maintaining circulation throughout our body daily until we die. Cardiac muscle fibers are shorter than skeletal muscles and most often contains only one nucleus located centrally in the cell. They are rich in mitochondria and myoglobin. The muscle cells here are branched and connected to each other by intercalated discs. These discs allow the pump to contract as one unit. Heartbeats, which are contractions of the heart are governed by the pace maker cells to regulate/control the heart rate. This muscle type is involuntary. It cannot be consciously controlled. For example, the cardiac muscle cells respond to signals from the Autonomic Nervous System(ANS) and hormones to help regulate blood pressure. The hormones and neurotransmitters that the cardiac cells respond to can speed up or slow down the pacemaker. Or in layman’s terms speed up or slow down your heart rate. Cardiac muscle is not easily fatigued.
3. Smooth Muscle
This type of muscle tissue gets its name from not having striations, hence smooth. They have a central nucleus are involuntary. Smooth muscle can be found in the GI tract, uterus, eye, blood vessels of the circulatory system, respiratory systems just name a few. These muscle tissues are wide in the middle and tapered at both ends. Some examples of smooth muscle function in the body, would be when you eat. After chewing your food, it is then propelled throughout the GI tract by peristalsis, which is done by the muscles lining the cavities of the GI tact, causing them to contract and relax, which in turn causes wavelike movement that propels the content of food through the Gi Tract. Without peristalsis, produced by smooth muscle, there will be no break down, or absorption of the food that we eat to get vital nutrients to sustain life. Another example would be the smooth muscle in the uterus, that causes contractions to push the baby out of the womb during child birth. Just like cardiac muscle, smooth muscle can respond to other stimuli, such as hormones and signaling form the nervous system( (Nature, 2014).
Properties of Muscle Tissue
In addition to sharing some of the same functions, they all share the same properties. The properties that they all share are, electrical excitability, contractility, extensibility, and elasticity (Crysta, 20018).
• Electrical excitability – is the muscles response to electrical stimuli from the nervous system, which causes an action potential to be elicited thereby causing the muscle to contract. Example think about touching a hot stove. A signal is sent to the CNS and one is sent back from the CNS to cause you to love your hand.
• Contractility – can shorten in length(contract) to create a force.
o Ex. the heart is a pump that uses force of the ventricles to force/ push blood into circulation.
• Extensibility – this is the ability of the muscle to be stretched.
• Elasticity- the ability of the muscle to recoil back to its original state (resting state), once it has be stretched.
Crysta, M. (20018, April 25). The Four Properties of Muscle Cells. Retrieved from Sciencing.com: https://sciencing.com/four-properties-muscle-cells-22946.html
Nature, B. S. (2014, September 24). Science: Human Body and Mind. Retrieved from Muscles- Skeletal, smooth amd cardiac: http://www.bbc.co.uk/science/humanbody/body/factfiles/skeletalsmoothandcardiac/heart_beat.shtml
OpenStax. (2013, March 6). Anatomy and Physiology. Retrieved from 10.7 Cardiac Muscle Tissue – Anatomy and Physiology: OpenStax, Anatomy ; Physiology. OpenStax CNX. Feb 26, 2016 http://cnx.org/contents/[email protected]