Chapter 10.1 Flashcards
What is muscle tissue specialized to do?
Convert chemical energy into kinetic energy
What physically happens when muscles contract?
They shorten
What are the 3 types of muscles cells?
Skeletal Muscle cells
Smooth Muscle cells
Cardiac Muscle cells
What is the description of skeletal muscle cells?
- Striated and tubular
- Have many nuclei
- Are usually attached to the bones of the skeleton
What is the description of smooth muscle cells?
- Non-striated
- Have one nucleus
- Contract involuntarily
- Are found in the walls of internal organs
What is the description of cardiac muscle cells?
- Are striated, tubular, and branched
- Have one nucleus
- Contract involuntarily
- Are found in the walls of the heart
Which muscles tissues are striated and contract voluntarily?
Skeletal muscle tissue and cardiac muscle tissue
Where is smooth muscle tissue found?
In the walls of internal organs
Where is skeletal muscle tissue found?
Attached to bones of the skeleton
Which muscles tissues have one nucleus?
Smooth and Cardiac
What is the physical appearance of smooth muscle tissue?
They are long and tapered at the end
Arranged in parallel lines
Forming sheets
Where is an example of smooth muscle tissue being found?
In the walls of certain blood vessels they can help to regulate blood flow by contracting
What controls the iris of the eye?
Smooth muscle tissue
How are the contractions of smooth muscle tissue vs. skeletal muscle tissue?
Smooth muscle tissue is slower to contract than skeletal muscle tissue, but it can sustain prolonged contraction
Where is cardiac muscle tissue unique to?
It is unique to the heart and forms the wall of the heart
How many nucleuses does cardiac muscle tissue have?
One nucleus
What is the contraction of cardiac muscle tissues like?
Contractions are involuntary
What do the cells of cardiac muscle tissue look like?
They are tubular striated
What is the meat of animals?
Skeletal Muscle Tissue
Why are skeletal muscle contraction voluntary?
Because contraction is consciously controlled by the nervous system
What do skeletal muscle cells look like?
Cells are very long and have many nuclei
Why do skeletal muscle tissues have many nuclei?
Because the cells are very long and require more energy and materials to be controlled by more than one nucleus
What are skeletal muscle cells often referred to as?
Fibres
How do skeletal muscles support the body?
The contraction of skeletal muscles opposes the force of gravity and enables us to stand upright
How do skeletal muscles make the bones move?
The muscular contractions account for movements of all parts of the body
How do skeletal muscle contractions help to maintain a constant body temperature?
Muscle contractions cause ATP to break down releasing heat, which is distributed throughout the body
How does skeletal muscle help protect internal organs and stabilize joints?
Skeletal muscles pad the bones that protect organs
It also has tendons that help hold the bones together at joints
Why can muscles only pull?
Because when muscles contract they shorten
When is the work of a muscle done?
During contractions
What is the passive state of the muscle?
Relaxation
What must there always be after a muscle contracts?
A force available to stretch a muscle after it contracts
Why are muscles always available in pairs?
Because there must always be a force to stretch a muscle after it contracts
What is the hierarchy of muscle structure?
Muscle Muscle-Fibre bundle Muscle Fibre Myofibrils Myofilaments
What does each muscle in the body lie along?
The length of a bone
What do tendons do?
Attaches each and of a muscle to a different bone
What are muscle fibres organized in?
Many larger bundles
What do muscles consist of?
They consist of clusters of bundles of muscles of muscle fibres
What do connective tissues wrap around?
A layer around each muscle fibre
A layer around each bundle of fibres
A layer around the whole muscle itselfs
What runs between bundles of muscle fibres?
Blood Vessels and nerves
Where do blood vessels and nerves run through in muscles?
Between bundles of muscle fibres
What do the blood vessels that run between muscles do?
Provide muscles fibres with nutrients and oxygen to power contractions and remove cellular wastes
What do the nerves that run between muscles do?
Trigger and control muscle contractions
What does most of the volume of a muscle fibre consist of?
Cylindrical subunits called myofibrils
What are myofibrils made of?
Myofilaments
What do myofilaments contain?
Protein structures responsible for muscle contractions
What is the volume of muscle fibres made up of?
Myofibrils and mitochondia
What is the cell membrane of a muscle fibre called?
The sarcolemma
What is the cytoplasm of a muscle fibre called?
Sarcoplasm
What are the 2 types of myofilaments?
Actin and Myosin
What does an actin myofilament consist of?
2 strands of protein molecules that are wrapped around each other like 2 strands of beads
What does a myosin filament consist of?
2 strands of protein molecules wound around each other. One end consists of a long rod while the other end consists of a double headed globular region
How long are myosin and actin filaments in comparison to each other?
Myosin filaments are about 10x longer than actin filaments
What first happens when a myofilament contracts?
The head of a myosin move first and the head moves backward and inward. Because the head is attached to the actin myofilament, the actin filament is pulled as well
What happens as a result of the actin filament being pulled when the myosin contracts?
The actin filament slides past the myosin in the direction of the flex
What happens as one myosin after another myosin flexes?
The myosin in affect walks step by step along the actin
How is ATP used when myofilaments contract?
ATP is needed to provide energy to reposition the myosin head before a flex
What is the sliding of actin past myosin a part of?
The sliding filament model of muscle contraction
Where is the actin anchored in the sliding filament model?
Actin is anchored at one end of each myofilament at a position in striated muscle tissue called the Z line
What happens as a result of actin being anchored at the Z line?
It’s movement pulls its anchor (the Z line) along with it
What happens as actin moves past myosin?
It drags the Z line toward the myosin
What does the mechanism of muscle contraction depend on?
The structural arrangements of myosin myofilaments in relation to pairs of actin myofilaments
What do the pairs of actin filaments do in the filament model of muscle contractions?
With one actin filament being pulled closer on each side, the Z lines toward each other as they pass the myosin core
What happens as the Z lines are brought closer together?
The plasma membranes which they are attached to move toward one another causing the whole muscle to contract
What is the positioning of myosin heads when the muscle is relaxed?
Myosin heads are raised and ready through the action of ATP
Why are myosin heads unable to bind with actin when the muscle is relaxed?
Because the attachment sites for myosin heads on the actin are blocked by another protein called tropomyosin
What does Tropomyosin do?
It is a protein the blocks myosin from bonding with actin when the muscle is rest
What must happen with tropomyosin for a muscle to contract?
Tropomyosin must be moved out of the way
How is is tropomyosin moved out of the way?
Another protein called troponin binds to the tropomyosin. This forms a complex that is regulated by calcium from the sarcoplasm
What happens when calcium concentration is low in the sarcoplasm?
Tropomyosin inhibits myosin binding and the muscle is relaxed
What happens when the calcium ion concentration in the sarcoplasm is raised?
The calcium binds to troponin. This creates a troponin-tropomyosin complex to be shifted away from attachment sites for myosin heads
What happens after the tropomyosin-troponin complex has been moved?
Myosin heads are able to attach to to the actin using ATP energy and move the actin filament to shorten the myofibril
What is the source of calcium ions for the process of moving the tropomyosin?
The sarcoplasmic reticulum
How are calcium ions released from the sarcoplasmic reticulum?
The muscle fibre is stimulated to contract and the calcium ion is released from the sarcoplasmic reticulum and diffuses into myofibrils
What happens to calcium ions when nerve impulses initiate muscles to stop contracting?
Nerve impulses initiate muscle contraction to stop and contractions stop, calcium ions returned to the sarcoplasmic reticulum through active transport
What are the 3 ways that muscles acquire ATP?
- The breakdown of creatine phosphate
- Aerobic cellular respiration
- Fermentation
What type of processes are Creatine Phosphate breakdown and Fermentation?
Anaerobic Processes
What is the first way the muscles acquire ATP?
Through Creatine Phosphate breakdown
How do muscles acquire energy if there is no oxygen available?
Through fermentation
What does fermentation cause in the body?
An oxygen defecit
What is Creatine Phosphate?
A high energy compound that builds up when a muscle is resting. It cannot directly participate when a muscle is contractions
How does creatine phosphate regenerate ATP?
Creatine breaks down in into creatine and phosphate. This energy is used to bind a phosphate group to ADP. This makes ATP
What is the speediest way to make ATP for the muscles?
The breakdown of creatine phosphate
How long does the the breakdown of creatine phosphate provide energy for the cell?
This energy lasts for about 8 seconds of intense activity
how is creatine phosphate rebuilt after it has been used up?
When the muscle is resting, through the transfer of phosphate group from ATP to creatine
Where does Aerobic Cellular Respiration take place?
In the mitochondria
What usually provides most of the muscles ATP?
Aerobic cellular respiration
What chemicals are stored in muscle cells for aerobic cellular respiration?
Glycogen and fat
What does a muscle fibre use from glycogen and fat to fuel the production of ATP when oxygen is available?
Glucose from Glycogen
and Fatty acids from fat
What is myoglobin?
An oxygen carrying molecule that is similar to hemoglobin that is synthesized in the muscle cells. It gives muscles its reddish brown color
How does myoglobin hold oxygen compared to hemoglobin?
Myoglobin can carry more oxygen than hemoglobin so it can temporarily store oxygen and transport it to the mitochondria
What are the products of aerobic cellular respiration?
ATP
Carbon Dioxide
Water
Heat
What are the reactants of aerobic cellular respiration?
ADP
Glucose
Oxygen
What happens to the resulting carbon dioxide from aerobic cellular respiration?
It exits through the lungs
Where does the majority of heat that warms the body come from?
Heat released from aerobic cellular respiration of skeletal muscle
What happens in fermentation?
Glucose is broken down to produce lactate. The energy released makes ADP into ATP
What happens due to the accumulation of lactate in the sarcoplasm of muscle cells?
It makes the sarcoplasm more acidic and enzymes stop functioning
What happens if fermentation occurs for more the 2-3 minutes?
Cramping and fatigue set in as a result from the lack of ATP that is needed to pump calcium ions back into the sarcoplasmic reticulum and break linkages between actin and myosin so that muscle fibres can relax
What happens when a muscle when it uses fermentation to supply its energy needs?
It incurs an oxygen defecit
What is the mitochondria like in athletes?
They have a higher level of ATP so they are able to start consuming oxygen as soon as ADP starts to rise
What can the mitochondria breakdown instead of glucose?
Fatty acids
What happens as a result of mitochondria breaking down fatty acids instead of glucose?
Blood glucose is spared and used for the activities of the brain
Why is less lactate produced by people who exercise?
Cause they are more able to use aerobic cellular respiration and don’t need to use fermentation which creates lactate
What does replenishing an oxygen deficit require?
Replenishing creatine phosphate supplies and disposing of lactate
What is the exhaustion of a marathon runner due to?
The runner has used up all of the muscles supply of glycogen
