Lab 4 Flashcards

Question

What is the sarcoplasmatic reticulum

Answer 1

The sarcoplasmic reticulum is a specialized membrane system that entraps Ca2+ ions when the muscles are at rest and releases them when a nerve impulse arrives.

Answer 2

On the border of A-band and I-band there is an indwelling of the cell membrane called the T transverse tubule, on both sides symmetrically there are reservoirs of the smooth sarcoplasmic reticulum (marginal cisterns). This arrangement is called a triad.

Answer 3

The action potentials arriving at the neuromuscular junction release acetylcholine (Ach) from the motor neurons. The Ach receptor, located in the cell membrane of the muscle fiber, is an ion channel that opens after Ach attaching to it. It triggers an inward Na+ current, responsible for depolarization of the cell membrane and the creation of an action potential. The action potential spreads along the muscle fiber to special cavities in the cell membrane called T-tubules.

Answer 4

The T channel is located adjacent to the marginal sarcoplasmic reticulum (SR) cistern. # The spreading wave of depolarization along the T tubule causes the release of calcium ions from the SR. The other SR fragments containing Ca2+ -ATPase are responsible for the re-accumulation of Ca2+ ions in the marginal cisterns of the SR, thus allowing the contraction to end.

Answer 5

Motor unit - it is a group of vertebrate skeletal muscle cells (muscle fibers) innervated by the same nerve cell, thus being jointly stimulated and simultaneously working (contracting). # The motor units of the same muscle may show different excitability

Answer 6

The threshold stimulus only activates the motor units with the lowest excitability threshold.

Answer 7

Stronger stimuli stimulate the contraction of units with a higher excitability threshold.

Answer 8

The maximum stimulus stimulates contraction of all motor units in the muscle.

Answer 9

The subtreshold stimuli are too weak to cause a contraction so no

Answer 10

A single nervous stimulus (α-motoneuron) causes the maximum contraction of all fibers of the motor unit innervated by it according to the "all or nothing" principle.

Answer 11

The strength of contraction, however, depends on the frequency of stimulation of a single motoneuron and the number of recruited motor units.

Answer 12

Unit recruitment depends on their excitability. S units (lowest excitable threshold) are recruited first, followed by FR units, finally FF.

Answer 13

They are present in: the wall of blood vessels the wall of the organs of the digestive and respiratory systems the urinary and genital organs the secretory/excretory ducts the in the eyeball the skin

Answer 14

They contract independently (you cannot consciously make them contract) They are innervated by the autonomic nervous system They constrict slowly with low energy consumption Contractions can be caused by different types of stimuli: nerve, mechanical, chemical, hormonal, or pacemaker cell stimuli

Answer 15

Fusiform mononuclear cells; 2x more actin and 4x less myosin than in skeletal muscle; No visible stripes.

Answer 16

There are dense bodies instead of the Z line of skeletal muscles. The contractile units are pseudosarcomers. Transverse bridges between actin and myosin are formed and the filaments slide one on another.

Answer 17

The maximum contractile tension developed by smooth muscles in terms of the cross-sectional area does not differ from that produced by striated muscles, but with from 100 to 1000 times less energy used. Smooth muscle contraction is very slow, the price paid for high energetic efficiency.

Answer 18

Intestinal cels of Cajal are an example of pacemaker cells in smooth muscle.

Answer 19

Gap junctions - thanks to them, the electrical potential spreads to neighboring myocytes.

Answer 20

A single contraction occurs when a muscle is subjected to a single stimulus or when the frequency of stimuli is so low that the next stimuli act after the muscle relaxes.

Answer 21

Incomplete tetanus contraction arises when a muscle is subjected to a series of stimuli of such frequency that subsequent stimuli act on the muscle after the contraction phase is over, during muscle relaxation.

Answer 22

Complete tetanus contraction arises when a muscle is subjected to a series of stimuli of such frequency that each successive stimulus acts in the contraction phase, even before its end.

Answer 23

The strength of the contraction increases as the frequency of the stimuli increases, because the contractions add up then.

Answer 24

The duration of the individual phases of contraction of a single frog calf muscle: period of latent excitation (A) = 0.01 s, contraction period (B) = 0.04 s, diastolic period (C) = 0.05 s

Answer 25

This type of contraction can be achieved by applying stimuli with a frequency of 10 to 25·s-1 on the frog calf muscle (for mammalian muscles the frequency will be higher). The phase of latent excitation occurs after the activation of the first stimulus and is the same as in a single contraction.

Answer 26

This type of contraction can be obtained using stimuli with a frequency of more than 25 · s-1 on the frog calf muscle (for mammalian muscles the frequency will be higher). The phase of latent excitation occurs after the activation of the first stimulus and is the same as in a single contraction.

Answer 27

The entire contraction of the smooth muscle from the frog's stomach may take about 100 seconds. The latent excitation period (A) is significantly extended and may last from 0.1 to 2 seconds. The contraction phase (B) is also longer in duration than in skeletal muscle. The duration of the diastolic phase (C) is usually many times longer than the systole phase. Smooth muscles do not undergo tetanic contractions.

Answer 28

An isometric contraction is a contraction in which the developed forces are unable to overcome the resistance, the muscle changes the tension, not the length.

Answer 29

Isotonic contraction is a contraction that in physiological conditions does not occur at all (it occurs when one attachment is free), the muscle changes length, while the tension does not change.

Answer 30

An auxotonic contraction is a typical contraction characteristic of muscle activity. In phase I, there is a contraction with no change in length, but with a change in tension - this is the isometric contraction phase. The muscle tenses to a degree that balances the load. Phase II is the shortening of the muscle while the tension remains unchanged - the isotonic phase.

Answer 31

Isotonic contraction - e.g. lifting a weight at a constant speed (constant tension) Isometric contraction - e.g. an attempt to lift a weight without taking it off the floor (the muscle does not shorten)

Answer 32

In isometric contraction, the tension produced by the muscle is less than the load, in the isotonic (and second auxotonic phase) the tension exceeds the load.

Answer 33

Number of transverse bridges (formed per unit time between the filaments of actin and myosin.)

Answer 34

Ensures the use of all actin-myosin bridges.

Answer 35

2.2 µm. The muscle resting length

Answer 36

1.Length of the muscle that is neither shortened nor stretched 2.Initially streched in living body- passive force created shortens length by 20% (Also shortened by 20% when muscle is isolated) 3. Muscle develops gretest strength at rest 4.When the sarcomere is stretched above 3.5 µm, there is no contact between the actin and myosin filaments, which prevents the formation of a contraction force. 5.If the stretching exceeded by approx. 3 times the resting length, the continuity of the muscle structure is broken and the muscle breaks.

Answer 37

Physiological cross-section of the muscle, i.e. perpendicular to the course of the fibers (spindleshaped vs, feathered)

Answer 38

Increase in the synthesis of contractile proteins, manifested by the thickening of individual cells.

Answer 39

1.Exercise 2.Hormones(T) 3.Growth factors 4.Sex 5.Age

Lab 4 Flashcards

(66 cards)