Henneman's size principle

(noun)

According to this principle, motor unit recruitment is always in the same order from smallest to largest motor unit. Additionally, the motor unit action potential is an all-or-none phenomenon—once the recruitment threshold (the stimulus intensity at which a motor unit begins to fire) is reached, it fires fully.

Related Terms

Examples of Henneman's size principle in the following topics:

  • Overview of Motor Integration

    • This is known as Henneman's Size Principle.

  • Counting Rules and Techniques

    • Several useful combinatorial rules or combinatorial principles are commonly recognized and used.
    • Each of these principles is used for a specific purpose.
    • More formally, the sum of the sizes of two disjoint sets is equal to the size of the union of these sets.
    • It considers the size of each set and the size of the intersections of the sets.
    • Since both expressions equal the size of the same set, they equal each other.

  • Limits on Animal Size and Shape

    • Animal shape and body size are influenced by environmental factors as well as the presence of an exoskeleton or an endoskeleton.
    • It is estimated that a doubling of body size increases body weight by a factor of eight.
    • The same principles apply to endoskeletons, but they are more efficient because muscles are attached on the outside, making it easier to compensate for increased mass.
    • As the body size increases, both bone and muscle mass increase.
    • Explain how the environment and skeletal structure can put limits on the size and shape of animals

  • Charles Darwin and Natural Selection

    • Charles Darwin and Alfred Wallace independently developed the theories of evolution and its main operating principle: natural selection.
    • In the years following this El Niño, the Grants measured beak sizes in the population and found that the average bill size was smaller.
    • Since bill size is an inherited trait, parents with smaller bills had more offspring and the size of bills had evolved to be smaller.
    • Natural selection, Darwin argued, was an inevitable outcome of three principles that operated in nature.
    • Both Darwin and Wallace were influenced by an essay written by economist Thomas Malthus who discussed this principle in relation to human populations.

  • The Galapagos Finches and Natural Selection

    • The differences in shape and size of beaks in Darwin's finches illustrate ongoing evolutionary change.
    • Natural selection, Darwin argued, was an inevitable outcome of three principles that operated in nature.
    • The year following the drought when the Grants measured beak sizes in the much-reduced population, they found that the average bill size was larger .
    • The Grants had studied the inheritance of bill sizes and knew that the surviving large-billed birds would tend to produce offspring with larger bills, so the selection would lead to evolution of bill size.
    • This caused an increase in the finches' average beak size between 1976 and 1978.

  • Microbial Growth Cycle

    • Increases in cell size are tightly linked in unicellular organisms and under optimal conditions bacteria can grow and divide rapidly.
    • All microbial metabolisms can be arranged according to three principles: 1) How the organism obtains carbon for synthesizing cell mass. 2) How the organism obtains reducing equivalents used either in energy conservation or in biosynthetic reactions. 3) How the organism obtains energy for living and growing (for more detail on this topic see atom on Growth Terminology).
    • Unlike in multicellular organisms, increases in cell size (cell growth and reproduction by cell division) are tightly linked in unicellular organisms.
    • Bacteria grow to a fixed size and then reproduce through binary fission which is a form of asexual reproduction.

  • Special topic: just-in-time and lean systems

    • In a manufacturing setting, there are six major ways to pursue JIT goals: inventory reduction to expose waste, use of a "demand-pull" production system, quick setups to reduce lot sizes, uniform plant loading, flexible resources, and cellular flow layouts.

  • When to retreat

    • Other conditions focus on sample size and skew.
    • For example, if the sample size is too small, the skew too strong, or extreme outliers are present, then the normal model for the sample mean will fail.
    • See Sections 1.3-1.5 for basic principles of data collection.

  • Cell Size

    • Cell size is limited in accordance with the ratio of cell surface area to volume.
    • In general, small size is necessary for all cells, whether prokaryotic or eukaryotic.
    • Therefore, as a cell increases in size, its surface area-to-volume ratio decreases.
    • This same principle would apply if the cell had the shape of a cube (below).
    • Notice that as a cell increases in size, its surface area-to-volume ratio decreases.

  • Caveat Emptor and the Gallup Poll

    • Generally, caveat emptor is the property law principle that controls the sale of real property after the date of closing, but may also apply to sales of other goods.
    • Under its principle, a buyer cannot recover damages from a seller for defects on the property that render the property unfit for ordinary purposes.
    • This principle can also be applied to the reading of polling information.
    • A larger sample size produces a smaller margin of error, all else remaining equal.
    • A random sample of size 1,600 will give a margin of error of $\frac{0.98}{40}$, or 0.0245 (just under 2.5%).