Interneuronal relay in spinal pathways from proprioceptors

Skeletal muscle adaptability : Significance for metabolism and performance

The sections in this article are:


1
Motor Unit
1.1
Fibers per Motor Unit

1.2
Contractile Properties

1.3
Biochemical Basis for Differences in Twitch Properties

1.4
Histochemical Differentiation of Muscle Fibers

1.5
Ultrastructural Basis for Skeletal Muscle Fiber Typing

1.6
Maximal Contractile Force

1.7
Speed of Contraction

1.8
Fatigue Characteristics

1.9
Metabolic Characteristics

1.10
Ionic Composition of Skeletal Muscle

1.11
Summary




2
Muscle Fiber Composition in Human Skeletal Muscle

3
Motor-Unit Recruitment

4
Adaptive Response in Skeletal Muscle
4.1
Muscle Size

4.2
Metabolic Capacity




5
Connective Tissue

6
Capillaries
6.1
Methodology

6.2
Anatomy

6.3
Capillary Density

6.4
Capillary Length and Diameter

6.5
Use and Disuse

6.6
Regulation




7
Significance of Adaptation
7.1
Muscular Size

7.2
Substrate Stores

7.3
Enzyme Activities

7.4
Summary

Skeletal Muscle Adaptability: Significance for Metabolism and Performance

Soluble glycoproteins have been purified from a series of clones of Trypanosoma brucei 427. Each clone yielded a characteristic predominant glycoprotein which induced clone-specific immunity to trypanosome infection in mice. These glycoproteins were shown by specific labelling and enzyme digestion of cells to be the major components of the trypanosome surface coat. Each glycoprotein consisted of a single polypeptide chain having an apparent molecular weight of 65 000 (as measured by SDS-polyacrylamide gel electrophoresis) and containing around 600 amino acid and 20 monosaccharide residues. Preliminary structural studies indicated large changes in amino acid sequence dispersed over a considerable length of the polypeptide chain. Proteolytic activity was demonstrated in semi-purified trypanosome extracts, providing one reason for the heterogeneity sometimes observed in surface glycoprotein antigen preparations.

Identification, purification and properties of clone-specific glycoprotein antigens constituting the surface coat of Trypanosoma brucei.

Background: Limb muscle dysfunction is prevalent in chronic obstructive pulmonary disease (COPD) and it has important clinical implications, such as reduced exercise tolerance, quality of life, and even survival. Since the previous American Thoracic Society/European Respiratory Society (ATS/ERS) statement on limb muscle dysfunction, important progress has been made on the characterization of this problem and on our understanding of its pathophysiology and clinical implications.Purpose: The purpose of this document is to update the 1999 ATS/ERS statement on limb muscle dysfunction in COPD.Methods: An interdisciplinary committee of experts from the ATS and ERS Pulmonary Rehabilitation and Clinical Problems assemblies determined that the scope of this document should be limited to limb muscles. Committee members conducted focused reviews of the literature on several topics. A librarian also performed a literature search. An ATS methodologist provided advice to the committee, ensuring that the methodological ...

/pdf/an-official-american-thoracic-society-european-respiratory-ah4dqvcuyd.pdf

An official American Thoracic Society/European Respiratory Society statement: update on limb muscle dysfunction in chronic obstructive pulmonary disease

1. The properties of fifty-seven motor units in human medial gastrocnemius have been studied using controlled intramuscular microstimulation, glycogen depletion and muscle biopsy. 2. Motor units could be divided into three classes on the basis of their mechanical properties. Type S units were slow, small and fatigue resistant. Type FR units were fast, intermediate in size, and fatigue resistant. Type FF units were fast, large and fatigable. 3. Glycogen depletion of a number of type S and FF units revealed them to be composed of type 1 and type 2b muscle fibres respectively. 4. The results suggest that during slowly increasing voluntary contractions where units are recruited in order of size, type 1 and 2a muscle fibres would be employed at low force levels followed by type 2b muscle fibres in stronger contractions.

Motor unit organization of human medial gastrocnemius.

1. By spike-triggered averaging of intracellular synaptic noise it has been shown in pentobarbitone anaesthetized cats that jaw elevator muscle spindle afferents with their cell bodies in the mid-brain have a relatively weak monosynaptic projection to masseter and temporalis motoneurones. 2. Extending the spike-triggered averaging method to recording extracellular excitatory field potentials it has been shown that virtually all the spindles do project monosynaptically to the motoneurone pool. It is concluded that the general weakness of the projection is due to its restriction to a small proportion of the motoneurones, possibly those concerned most with tonic postural functions. 3. The shape of individual intracellular e.p.s.p.s together with the spatial distribution of extracellular excitatory potential fields provide some evidence for a dentrically weighted distribution of the synapses. 4. Evidence is presented that both primary- and secondary-type spindle afferents project monosynaptically, the secondary effects being some 71% of the strength of the primary ones.

https://physoc.onlinelibrary.wiley.com/doi/pdf/10.1113/jphysiol.1978.sp012353

The projection of jaw elevator muscle spindle afferents to fifth nerve motoneurones in the cat

Methods of cultivating parasites in vitro.

Aquatic invertebrates were found to be affected to very different extents by water saturated with oxygen; some species were quickly killed, others were slowly injured, while yet others showed no ill effects in the course of weeks. Many of the animals studied lived equally well in fully aerated and in one-fifth aerated water, only a few species surviving longer in the former. Some mud-dwellers lived longer in the less well aerated water. The young of some species grew bigger in one-fifth aerated than in fully aerated water.

Angela E.R. Taylor

Papers

Motor unit organization of human medial gastrocnemius.

The projection of jaw elevator muscle spindle afferents to fifth nerve motoneurones in the cat

Methods of cultivating parasites in vitro.

The Tolerance of Oxygen by Aquatic Invertebrates

The cultivation of parasites in vitro