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
What is Plantar flexion?
Pointing the toes down
What is Abduction?
Moving a body part away from the midline of the body
What is Adduction?
Moving a body part toward the midline of the body
What is Rotation?
Twisting or rotating a body part
What is Circumduction?
Moving a body part in a circle
What is Pronation?
Turning the palm of the hand down or lying face down on the abdomen
What is Supination?
Turning the palm of the hand up or lying face up on the back
What is inversion?
Turning the sole of the foot medially so that the soles of the feet can touch each other
What is Eversion?
Turning the sole of the foot laterally so that the soles of the feet are pointing away from each other
What is Retraction?
Moving a body part posteriorly
What is Protraction?
Moving a body part anteriorly
What is Elevation
Lifting a body part
What is Depression?
Lowering a body part
What is Opposition?
Bringing together each of the fingers and the thumb
What is Fibromyalgia?
Causes are poorly understood
Pain in muscles, joints and tendons
Fatigue, tenderness in different areas of the body, sleep disturbances, and chronic pain
Antidepressants, anti-inflammatory medications, physical therapy, lifestyle changes to reduce stress, counseling to improve coping skills
What is Muscular Dystrophy ?
Seven types of MD- -Muscle weakness and loss of muscle tissue
Most common forms are Duchenne’s (faster) and Becker’s MD
X-linked (from mom to son), hereditary disorder
Muscle weakness in various muscle groups, depending on the type of dystrophy
Muscle bioposy, DNA, EMG, ECG
Physical therapy, use of braces and wheelchairs, various medications, and surgery to avoid or treat contracture
What is Myasthenia Gravis?
Autoimmune disorder -prevents muscles from receiving neurotransmitters
Symp: Diplopia (double vision), muscle weakness, ptosis (droopy eyelid), dysphagia (hard to swallow), difficulty talking, fatigue, and drooling
EMG test - if muscle responds to stimuli
ACH receptor tests
Tensilon test increase of muscle activity as medication blocks ACH breakdown
Avoid excessive stress, getting adequate rest, using heat on muscles, using an eye patch to treat double vision, taking medications to improve communication between nerves and muscles, immunosuppressants, and plasmapheresis (remove antibodies from blood)
What is tendonitis?
Occurs after a sports-related or other repetitive activity that results in injury to the muscle–tendon or tendonto- bone attachment
Pain at the joint or muscle attachment that results in limited range of motion - associated with bursititis
Acute phase - ice should be used to minimize inflammation; followed by heat application; resting the affected area and oral analgesics
What is tetanus or lockjaw?
Caused by the toxin produced Clostridium tetani which is found in soil and water
Muscle spasms of face, neck, and jaw usually occur 5 to 10 days after infection
Immediate treatment with antitoxins and antibiotics is needed to prevent death or long-lasting effects
Regular vaccinations prevent this disease
What is Tetany?
Low blood calcium
Muscle cramps and spasms, uncontrolled twitching, and in severe cases, seizures
Calcium and vitamin D supplements, parathyroid hormone may also be used
What is Torticollis or “Wry Neck”
twisted neck - Head bends toward the side of the contracted muscle while the chin rotates to the opposite side
May be congenital or acquired
Headaches, inflammation, and pain of neck muscles
Passive exercises to stretch the muscles and corrected head positioning during sleep
Heat, cervical traction, neck brace, exercise, massage