Muscles Flashcards
Skeletal muscles:
Voluntary striated muscle that is attached to bones
Human muscular tissue makes up 40-50% of body weight
What are the physiological characteristics of muscle?
1 Irritability (responsiveness) 2 Contractility 3 Elasticity 4 Conductivity 5 Extensibility
ICECE
Irritability
- Irritability
- Property of all living cells
- Muscles and nerve cells develop this property to the highest degree
- referred to as excitability
- receives stimuli (e.g cold, a change in environment) and responds to them.
- muscle response to the stimuli is contraction
Contractility
Enables muscles to change their shape and become shorter and thicker
Elasticity
When a muscle cell is stretched and then tension is released, it recoils to its original resting length.
The return to the original length when tension is released
Conductivity
Stimulation of a muscle fibre produces more than a local effect
The local electrical change triggers a wave of excitation that travels rapidly along the fibre and initiates processes leading to muscle contraction
Extensibility
In order to contract, a muscle cell must also be extensible - able to stretch again between contractions
Skeletal muscle fibres can stretch as much as 3x their contracted length
(Most cells rupture if stretched a little)
All motion in the body is due to three types of muscles
- Skeletal (striated)
- Smooth
- Cardiac
Skeletal / Striated muscle
Skeletal muscle contraction allows for movement of the entire body and is under voluntary control.
Skeletal muscles are attached to bones and make up a large percentage of body mass
Nerve impulses trigger a reaction from the muscle which contracts, moving its associated bone or joint
Smooth muscle/ non-striated muscles
- also known as involuntary/ visceral
- function automatically, without conscious will
- these muscles are found in the digestive and circulatory system and some internal organs of the body
Cardiac muscle
The involuntary muscle that makes up the heart
It is unique and not found in any other part of the body
It is striated and has a crossing, banding pattern that allows contraction; thus beating of the heart
It is under the control of the autonomic nervous system
Muscles are attached to the bone by;
Structures of connective tissue with extensions of loose fibres called tendons
Muscle is always under some degree of contraction which is referred to as:
Tone
Tone of the skeletal muscle gives firmness and maintains a slight steady pull on the attachment even when the muscle is at rest
What are the three parts of a muscle?
- The origin
- The belly
- The insertion
The origin
Is the more fixed part of the muscle closest to the skeleton, which flexes but remains stationary
