Muscular System Flashcards
What are the three types of muscles?
Cardiac, smooth, and skeletal
Where are cardiac muscles found?
The heart
What type of contraction occurs in cardiac muscles?
Involuntary contraction
What controls the cardiac muscles?
Nerves of the autonomic nervous system
Are cardiac muscles striated or not?
Striated
What is the cardiac muscle, meaning that it is self-excitable stimulating contraction without a required electrical impulse coming from the central nervous system?
Myogenic
Where are smooth muscles found?
The lining of many organs and in hollow parts of the body
What are some organs that smooth muscles are found in?
Stomach, esophagus, uterus, and walls of blood vessels
What type of contraction occurs in smooth muscles?
Involuntary contraction
Are smooth muscles striated or not?
Non-Striated
What are skeletal muscles?
Muscles that are attached to bone
What type of contraction occurs in skeletal muscles?
Voluntary contraction
What controls the voluntary contraction of skeletal muscles?
The somatic nervous system
What attaches skeletal muscles to bones?
Tendons
What is 80% of all energy used in muscle contraction lost as?
Heat
Are skeletal muscles striated or not?
Striated
What happens to muscles when they contract?
Shorten
What happens to muscles when they relax?
Lengthen
What sends excitatory or inhibitory nerve impulses to the skeletal muscles, causing them to either contract or relax?
The central nervous system
Skeletal muscles are composed of many bundles of cells called what?
Fibres
What are the fibres enclosed within?
A membrane called sarcolemma
What is within the muscle fibre that are bundled together?
Myofilaments
What are the two main types of myofilament?
Thin myofilament and thick myofilament
What is thin myofilament composed of?
Actin (light bands)
What is thick myofilament composed of?
Composed of myosin (dark bands)
These two types of myofilaments overlap to produce what type of appearance?
Striated
What is released from a nerve to the muscles, signalling contraction?
A neurotransmitter
What does the muscles cell’s endoplasmic reticulum release near the actin?
Calcium (Ca2+ ions)
What do the calcium ions attach to?
The actin
What is allowed to attach to the actin after the the calcium ions?
Myosin
What is formed when myosin attaches to actin?
Actin-myosin cross-bridge
The actin and myosin continually attach and de-attach over and over, with each re-attachment of the actin what happens to the muscles?
The muscle fibres get pulled closer together carrying on until full contraction of the muscles occurs
Calcium ions also start the break down of ATP, which allows the actin to do what?
De-attach each time from the myosin and also provides energy for the reaction to occur (when ATP is broken down energy is given off)
What occurs if no ATP is present?
Rigor mortis
When does rigor mortis occur?
After death; myosin and actin stay attached leaving the muscles fully contracted
What is muscle soreness, fatigue, burning, tightness, etc. attributed to?
Due to the fact that very little ATP can be stored in the muscle tissue; as a result Aerobic CR constantly provides/replenishes most of the energy in the form of ATP
As soon as the ATP is used up and converted back to ADP, what compound ensures all ADP is converted back to ATP?
Creatine phosphate
What is a supplement used by athletes to increase muscle strength?
Creatine
When will fatigue occur?
If ATP demands can not be met
What happens that causes fatigue?
Lactic acid begins to build up, muscles tighten up, and fatigue takes over
What is atrophy?
The reduction in size, tone and power of a muscle due to decreased use and stimulation; can eventually lead to permanent loss of muscle function
What is hypertrophy?
An exercise-induced increase in muscle mass resulting from an increase in the size of individual muscle fibres
Does atrophy and hypertrophy result in a change in the number if muscle fibres?
No
What is a muscle twitch?
A muscular contraction that lasts for a fraction of a second
What is the latent stage?
Time between stimulus and initiation of the contraction; 1
What is the contraction stage?
Time it takes for the muscle fibres to shorten; Ca2+; 2
What is the relaxation stage?
Time it takes for the muscle to return to its regular length; ATP; 3
What are slow-twitch fibres?
Fibres that contract slowly and resist fatigue because they are surrounded by more blood vessels and have more mitochondria; aerobic
What are fast twitch-fibres?
Fibres that contract quickly to give more power, but depend upon aerobic energy production. They are rich in glycogen, and have fewer mitochondria and blood vessels surrounding them; anaerobic
What type of training impacts slow-twitch fibres?
Endurance training; no impact on size
What type of training impacts fast-twitch fibres?
Strength/resistance training; thickens
What is tetanus?
A state of constant muscle contraction
What are muscle spasms?
Involuntary contraction of a muscle, often caused by a pinched nerve
