Bio 201 Muscle Physiology Paper
Bio 201: Human Anatomy and Physiology I
Muscle Physiology Protocol
I. Goals for this lab
A. To increase your understanding of muscle physiology - tonus, motor unit recruitment and fatigue.
B. Learn how to conduct and analyze an EMG (electromyogram)
C. To gain more experience with the scientific method, experimental design, making predictions, critical analysis of results, and interpretation of your results.
II. Introduction
Human skeletal muscle consists of hundreds of individual cylindrically shaped cells (called fibers or myofibers) bound together by connective tissue. In the body, these muscles are stimulated to contract by somatic motor nerves that carry signals in the form of nerve impulses from the brain or spinal cord …show more content…
This principle is called the length–tension relationship. The reasons for it can be seen in figure 1.2. If a fiber is overly contracted at rest, its thick filaments are rather close to the Z discs. The stimulated muscle may contract a little, but then the thick filaments butt against the Z discs and can go no farther. The contraction is therefore a weak one. On the other hand, if a muscle fiber is too stretched before it is stimulated, there is relatively little overlap between its thick and thin filaments. When the muscle is stimulated, the myosin heads cannot “get a good grip” on the thin filaments, and again the contraction is …show more content…
At low frequency, the muscle relaxes completely between stimuli and shows twitches of uniform strength. (b) Treppe. At a moderate frequency of stimulation, the muscle relaxes fully between contractions, but successive twitches are stronger. (c) Wave summation and incomplete tetanus. At still higher stimulus frequency, the muscle does not have time to relax completely between twitches and the force of each twitch builds on the previous one. (d) Complete tetanus. At high stimulus frequency, the muscle does not have time to relax at all between stimuli and exhibits a state of continual contraction with about four times as much tension as a single twitch. Tension declines as the muscle fatigues. Only the conditions in parts (b) and (c) occur in the human body; those depicted in (a) and (d) are produced only by artificial stimultion below or above the range of nerve firing
Muscle Physiology Protocol
I. Goals for this lab
A. To increase your understanding of muscle physiology - tonus, motor unit recruitment and fatigue.
B. Learn how to conduct and analyze an EMG (electromyogram)
C. To gain more experience with the scientific method, experimental design, making predictions, critical analysis of results, and interpretation of your results.
II. Introduction
Human skeletal muscle consists of hundreds of individual cylindrically shaped cells (called fibers or myofibers) bound together by connective tissue. In the body, these muscles are stimulated to contract by somatic motor nerves that carry signals in the form of nerve impulses from the brain or spinal cord …show more content…
This principle is called the length–tension relationship. The reasons for it can be seen in figure 1.2. If a fiber is overly contracted at rest, its thick filaments are rather close to the Z discs. The stimulated muscle may contract a little, but then the thick filaments butt against the Z discs and can go no farther. The contraction is therefore a weak one. On the other hand, if a muscle fiber is too stretched before it is stimulated, there is relatively little overlap between its thick and thin filaments. When the muscle is stimulated, the myosin heads cannot “get a good grip” on the thin filaments, and again the contraction is …show more content…
At low frequency, the muscle relaxes completely between stimuli and shows twitches of uniform strength. (b) Treppe. At a moderate frequency of stimulation, the muscle relaxes fully between contractions, but successive twitches are stronger. (c) Wave summation and incomplete tetanus. At still higher stimulus frequency, the muscle does not have time to relax completely between twitches and the force of each twitch builds on the previous one. (d) Complete tetanus. At high stimulus frequency, the muscle does not have time to relax at all between stimuli and exhibits a state of continual contraction with about four times as much tension as a single twitch. Tension declines as the muscle fatigues. Only the conditions in parts (b) and (c) occur in the human body; those depicted in (a) and (d) are produced only by artificial stimultion below or above the range of nerve firing