Muscle Contraction Essay
Muscle contractions tend to be smooth and vary in strengths, depending on the demands placed on them. The variations of strength are called graded muscle responses. There are two ways a muscle contraction can be graded, either by changing the frequency of stimulation or by changing the strength of the stimulation. When a muscle is responding to a change in stimulus frequency, the nervous system will reach a greater muscular force when increasing the firing of motor neurons. This causes a wave or temporal summation, which is when the second twitch of the muscle is stronger than the first. This occurs because the second contraction occurs before the muscle has completely relaxed and more Ca2+ is still being released, which causes more shortening
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of the muscle than in the first. When a muscle is responding to change in the strength of a stimulation, the amount of muscle cells contracting differs. The more muscle cells contracting, the stronger the contraction.
Contractions refer to the activation of myosin’s cross bridges. In smooth muscle contraction, the muscle fibers contract slowly and simultaneously because of coupling by the gap junctions. Smooth muscle stretches more than skeletal muscle and creates more tension. Contractions in smooth muscle are brief and occur when the muscle is stretched. Smooth muscle does not use as much ATP as skeletal muscle. The autonomic nervous systems release of hormones such as acetylcholine and norepinephrine can result in excitation or contraction of smooth muscle cells.
In both smooth and skeletal muscle, thin filaments slide past the thick filaments so that the actin and myosin filaments overlap.
ATP is the source of energy for the sliding. They both experience an increase in calcium for muscle contraction, and a decrease when the muscle relaxes. The cross-bridge attachments form and break multiple times during a contraction to help create more tension.
The digestive system creates and ideal environment for the functioning of the GI tract. The GI tract initiates the digestive system by triggering mechanical and chemical stimuli that can be detected by chemoreceptors and mechanoreceptors. The activation of the digestive system can be either extrinsic or intrinsic; nervous or hormonal. The enteric nervous system is responsible for the short and long reflexes of the digestive system. The short reflexes control smooth muscle contractions and glandular secretions of the digestive tract. Long reflexes have to do with interneurons and motor neurons in the central nervous system. These provide more control over the digestive and glandular activates. Hormonal process’ involve about 18 hormones, each affecting digestive functioning. Local mechanisms involve prostaglandins, histmins, and other chemicals that are released into the interstitial
fluid.
Gastric glands in the stomach produce gastric juice. The cell types responsible for secreting the various components of gastric juice are mucous neck cells, parietal cells, chief cells, and enteroendocrine cells.
Mucous neck cells produce a thin, soluble, acidic mucous. Parietal cells secrete HCL. HCL makes the stomach’s content acidic. It helps to denature proteins, kills bacteria, and break down cell walls. This is also required for the process of absorbing vitamin B12 in the small intestine. Chief cells produce pepsinogen, which catalyzes to pepsin. They secrete lipases, which digest fats. Enteroendocrine cells are found deep in the gastric glands and release chemical messengers like histamine, serotonin, somatostatin, and gastrin, directly into interstitial fluid of the lamina propria.
of the muscle than in the first. When a muscle is responding to change in the strength of a stimulation, the amount of muscle cells contracting differs. The more muscle cells contracting, the stronger the contraction.
Contractions refer to the activation of myosin’s cross bridges. In smooth muscle contraction, the muscle fibers contract slowly and simultaneously because of coupling by the gap junctions. Smooth muscle stretches more than skeletal muscle and creates more tension. Contractions in smooth muscle are brief and occur when the muscle is stretched. Smooth muscle does not use as much ATP as skeletal muscle. The autonomic nervous systems release of hormones such as acetylcholine and norepinephrine can result in excitation or contraction of smooth muscle cells.
In both smooth and skeletal muscle, thin filaments slide past the thick filaments so that the actin and myosin filaments overlap.
ATP is the source of energy for the sliding. They both experience an increase in calcium for muscle contraction, and a decrease when the muscle relaxes. The cross-bridge attachments form and break multiple times during a contraction to help create more tension.
The digestive system creates and ideal environment for the functioning of the GI tract. The GI tract initiates the digestive system by triggering mechanical and chemical stimuli that can be detected by chemoreceptors and mechanoreceptors. The activation of the digestive system can be either extrinsic or intrinsic; nervous or hormonal. The enteric nervous system is responsible for the short and long reflexes of the digestive system. The short reflexes control smooth muscle contractions and glandular secretions of the digestive tract. Long reflexes have to do with interneurons and motor neurons in the central nervous system. These provide more control over the digestive and glandular activates. Hormonal process’ involve about 18 hormones, each affecting digestive functioning. Local mechanisms involve prostaglandins, histmins, and other chemicals that are released into the interstitial
fluid.
Gastric glands in the stomach produce gastric juice. The cell types responsible for secreting the various components of gastric juice are mucous neck cells, parietal cells, chief cells, and enteroendocrine cells.
Mucous neck cells produce a thin, soluble, acidic mucous. Parietal cells secrete HCL. HCL makes the stomach’s content acidic. It helps to denature proteins, kills bacteria, and break down cell walls. This is also required for the process of absorbing vitamin B12 in the small intestine. Chief cells produce pepsinogen, which catalyzes to pepsin. They secrete lipases, which digest fats. Enteroendocrine cells are found deep in the gastric glands and release chemical messengers like histamine, serotonin, somatostatin, and gastrin, directly into interstitial fluid of the lamina propria.