Summation, in physiology,
the additive effect of several electrical impulses on a neuromuscular junction
, the junction between a nerve cell and a muscle cell. Individually the stimuli cannot evoke a response, but collectively they can generate a response.
What is muscle wave summation?
A
motor unit
of a muscle responds to a single stimulus with a simple twitch response. When a second stimulus is applied to the motor unit before the response to the first is completely lost, the two responses combine to produce a greater muscle tension than that produced by a single response.
Why does summation of contraction occur?
At the molecular level, summation occurs because
the second stimulus triggers the release of more Ca
++
ions
, which become available to activate additional sarcomeres while the muscle is still contracting from the first stimulus. Summation results in greater contraction of the motor unit.
What is the difference between summation and tetanus?
Summation and Tetanus Contractions: Repeated twitch contractions, where the previous twitch has not relaxed completely are called a summation. If the frequency of these contractions
increases to the point where maximum tension is generated
and no relaxation is observed then the contraction is termed a tetanus.
What is summation and why is it important?
Summation of excitatory
postsynaptic potentials increases the probability that the potential will reach the threshold potential and generate an action potential
, whereas summation of inhibitory postsynaptic potentials can prevent the cell from achieving an action potential.
What are the 4 types of muscle contractions?
Isometric
: A muscular contraction in which the length of the muscle does not change. isotonic: A muscular contraction in which the length of the muscle changes. eccentric: An isotonic contraction where the muscle lengthens. concentric: An isotonic contraction where the muscle shortens.
Why is tetanus important for muscle contraction?
Fused tetanus is
when there is no relaxation of the muscle fibers between stimuli and it occurs during a high rate of stimulation
. A fused tetanic contraction is the strongest single-unit twitch in contraction. … During tetanic contractions, muscles can shorten, lengthen or remain constant length.
How does muscle summation work?
Summation can be achieved by
increasing the frequency of stimulation
, or by recruiting additional muscle fibers within a muscle. occurs when the frequency of muscle contraction is such that the maximal force is tension is generated without any relaxation of the muscle.
What is the meaning of muscle fatigue?
1
. Muscle fatigue is defined as
a decrease in maximal force or power production in response to contractile activity
.
5
. It can originate at different levels of the motor pathway and is usually divided into central and peripheral components.
What are some causes of muscle fatigue?
- Addison’s disease.
- age.
- anaerobic infections.
- anemia.
- anxiety.
- botulism.
- cerebral palsy.
- chemotherapy.
What are the two types of summation?
There are two types of summation:
spatial summation and temporal summation
that occur between neurones.
What is an example of a Multipennate muscle?
A type of pennate muscle wherein the diagonal muscle fibers are in multiple rows with the central tendon branching into two or more tendons. Example of multipennate muscle is
deltoid muscle
.
What are the 2 types of muscle fibers?
The two types of skeletal muscle fibers are
slow-twitch (type I) and fast-twitch (type II)
. Slow-twitch muscle fibers support long distance endurance activities like marathon running, while fast-twitch muscle fibers support quick, powerful movements such as sprinting or weightlifting.
What is the role of summation?
Summation, in physiology,
the additive effect of several electrical impulses on a neuromuscular junction
, the junction between a nerve cell and a muscle cell. Individually the stimuli cannot evoke a response, but collectively they can generate a response.
What do you mean by summation?
1 :
the act or process of forming a sum
: addition. 2 : sum, total. 3 : cumulative action or effect especially : the process by which a sequence of stimuli that are individually inadequate to produce a response are cumulatively able to induce a nerve impulse.
Where does summation occur?
This process is called summation and occurs at
the axon hillock
, as illustrated in Figure 1. Additionally, one neuron often has inputs from many presynaptic neurons—some excitatory and some inhibitory—so IPSPs can cancel out EPSPs and vice versa.
