Flashcards in Ch 9 - Muscular System Deck (51)
What do muscles do?
Muscles can only do one thing: contract.
Muscle contraction acts to:
Move bones, circulate blood, and move food through the digestive system
More than 600 individual skeletal muscles
What are three types of muscles
Skeletal-striated, multiple nuclei, body and face movements, voluntary
Cardiac - heart, striated, Single nuclei, involuntary, intercalating discs
Smooth - walls of hollow organs, blood vessels, involuntary,
What is Multiunit smooth muscle ?
When one fiber is stimulated, many adjacent fibers are also stimulated.
Allows pupil size to change, expansion and contraction in lungs, respond to neurotransmitters
What is visceral smooth muscle ?
Known as single unit. Walls of hollow organs
Sheets of cells in close contact with each other
Has autorhythmicity like cardiac muscle - contract and relax together
Cells are tapered and have a single nucleus.
No visible striations, even though they have actin and myosin filaments
What is peristalsis?
action produced by smooth muscle
Rhythmic contraction that pushes substances through tubes of the body
Helps moves food down from esophagus to stomach
Responds to acetylcholine (ACh) cause contractions
What is skeletal muscle?
Striated or voluntary muscle
Actin and myosin filaments responsible for the striations
Body movement, maintaining of posture, and heat generation through shivering
Responds to Acetylcholine by contracting. After contracting Acetylcholinesterase is released and it breaks down ACh and causes muscle relaxation
What is cardiac muscle?
Found in the heart- Cells are called cardiomyocytes.
Heart acts as a pump that moves blood.
Like smooth muscle - involuntary muscle
Responds to ACh (slows down heart) and norepinephrine (speeds up heart) like skeletal muscle
Has striations created by the overlapping of thick (myosin) and thin (actin) contractile proteins known as filaments
Lots of mitochondria due to high energy demand
Cross bands called intercalated discs that permit the cells to work as a single unit
In addition to having nerves innervate the heart, the heart is also autorhythmic.
What are muscle cells called?
Myocytes or muscle fibers . They are controlled by motor neurons that release neurotransmitters
What is the cell membrane of a skeletal muscle fiber called
It is called a sarcolemma
What is the cytoplasm and ER of a skeletal muscle cell called?
The cytoplasm is called sarcoplasm, its filled with myofibrils. The actin and myosin filaments in myofibrils produce striations
The ER is called the sarcoplasmic reticulum
What is the structure of skeletal muscle cell?
A group of muscle fibers is called fascicle. It is surrounded by endomysium, which is surrounded by perimysium. The epimysium is dense irregular connective tissue that surrounds an entire muscle.
What is Fascia ?
Connective tissue located just below the skin
Helps support muscles, bones, nerves, and blood vessels
What is tendon?
tough, cord-like structure made of fibrous connective tissue
Connects a muscle to a bone
What is ligament?
Tough fibrous connective tissue
Binds bone to bone
What is Aponeurosis?
broad, sheet-like structure.
Fibrous connective tissue
Attaches muscles to other muscles
What is Creatine phosphate?
Source of ATP
formed when there is an excess of ATP
Transfers phosphate to ADP to make new ATP
High-energy molecule that is stored in the muscle cell
Provide enough energy for about 15 seconds of muscle activity
What is Anaerobic respiration?
Glucose is used to generate ATP when creatine supply is gone
Glucose, derived from the blood and from glycogen (stored in liver and muscle fibers), is used to generate ATP
Glycolysis breaks down glucose into molecules of pyruvic acid and produces two molecules of ATP
If oxygen levels are low, pyruvic acid is converted to lactic acid which is carried away by the blood.
Provides enough energy for about 30 to 40 seconds of muscle contraction
What is Aerobic respiration?
Uses bodys own store of glucose and O2
Glucose is broken down into pyruvic acid using oxygen.
Converted into acetyl coenzyme A, beginning a series of reactions known as the citric acid cycle
Oxygen needed for aerobic respiration is derived from a muscle pigment called myoglobin
Provides most of the ATP for activities > 10 minutes
Pyruvic acid is oxidized in the mitochondria of muscle cells producing 36 ATP molecules for every molecule of glucose, carbon dioxide, water, and heat
What are the 3 ways oxygen is used to return the muscle fibers to their resting state?
Lactic acid is converted to glycogen.
Creatine phosphate and ATP are synthesized
Oxygen is replaced in the myoglobin.
What is muscle fatigue?
Muscle has temporarily lost its ability to contract
During oxygen debt because of the accumulation of lactic acid in the muscle
Blood supply to a muscle is interrupted
Motor neuron loses its ability to release ACh
Painful, involuntary contractions of muscles
How is movement produced?
a muscle must cross a joint and have at least two attachments to bone
Attachment site of a muscle to the less moveable bone during muscle contraction
Attachment site of a muscle to the more movable bone during muscle contraction
What is the prime mover?
Muscle responsible for most of the movement
What is the agonist?
Assists the prime mover
What is the Synergist?
Help the prime mover by stabilizing joints
What is the Antagonist ?
Produces a movement opposite to that of the prime mover
When the prime mover contracts, the antagonist must relax in order to produce a smooth body movement.
What is Flexion?
Bending a body part or decreasing the angle of a joint
What is Extension?
Straightening a body part or increasing the angle of a joint
What is Hyperextension?
Extending a body part past the normal anatomical position
What is Dorsiflexion?
Pointing the toes up