Questions and Answers
Which muscle is primarily responsible for raising the eyebrows?
What is the primary action of the orbicularis oris muscle?
Where do intrinsic tongue muscles originate?
Which muscle group is responsible for elevating or stabilizing the hyoid bone?
Signup and view all the answers
Which muscle is known as the smiling muscle?
Signup and view all the answers
What is the primary function of the external intercostals?
Signup and view all the answers
Which muscle is responsible for compressing the abdomen?
Signup and view all the answers
How do the internal intercostals function during breathing?
Signup and view all the answers
What is the role of the diaphragm in breathing?
Signup and view all the answers
Which group of muscles seeks to elevate the pharynx?
Signup and view all the answers
What is primarily responsible for the banding patterns in skeletal muscle tissue?
Signup and view all the answers
Which ion channels are involved in producing an action potential?
Signup and view all the answers
What is the role of synaptic vesicles at the neuromuscular junction?
Signup and view all the answers
What occurs during the sliding filament model of muscle contraction?
Signup and view all the answers
What happens to the A bands during muscle contraction?
Signup and view all the answers
Where do motor neurons interact with muscle fibers?
Signup and view all the answers
What structure specifically connects the presynaptic terminal to the postsynaptic membrane?
Signup and view all the answers
What is the function of neurotransmitters in muscle contraction?
Signup and view all the answers
What starts the process of muscle contraction in the sliding filament theory?
Signup and view all the answers
Which ion is responsible for causing synaptic vesicles to release acetylcholine?
Signup and view all the answers
What is the role of acetylcholine in muscle contraction?
Signup and view all the answers
What happens after Na+ channels open in the postsynaptic terminal?
Signup and view all the answers
What is the effect of Ca2+ binding to troponin during muscle contraction?
Signup and view all the answers
What occurs as myosin heads bend toward the center of the sarcomere?
Signup and view all the answers
What happens after muscle contraction is initiated and acetylcholinesterase is released?
Signup and view all the answers
During the sliding filament mechanism, what is released from myosin heads?
Signup and view all the answers
What happens to ATP during muscle contractions?
Signup and view all the answers
Which statement about slow twitch fibers is true?
Signup and view all the answers
Which type of muscle fiber primarily uses glycogen for energy?
Signup and view all the answers
What is rigor mortis caused by?
Signup and view all the answers
What defines the all-or-none law related to muscle contractions?
Signup and view all the answers
What is the primary function of myoglobin in muscle fibers?
Signup and view all the answers
Which statement is true regarding muscle origin and insertion?
Signup and view all the answers
What causes muscle tone?
Signup and view all the answers
Study Notes
Muscle Structure and Function
- Two adjacent sarcomeres display banding patterns critical for muscle function.
- Sarcomeres consist of actin and myosin myofilaments responsible for muscle contraction via the sliding filament model.
- During contraction, actin and myosin slide past each other, shortening the muscle without reducing filament lengths.
Excitability and Action Potentials
- Resting cells have sodium (Na+) and potassium (K+) channels closed.
- Action potentials occur as Na+ channels open and close, altering charge differences across the plasma membrane.
- Motor neurons transmit action potentials to muscle fibers at the neuromuscular junction.
Neuromuscular Junction Components
- Motor neuron communicates with a muscle fiber through the neuromuscular junction (synapse).
- Key structures include the presynaptic terminal, postsynaptic membrane, synaptic cleft, synaptic vesicles, and neurotransmitters (e.g., acetylcholine).
- Motor units consist of muscle fibers stimulated by a single motor neuron.
Muscle Contraction Mechanism
- Muscle contraction begins when an action potential travels down the motor neuron.
- Calcium ions (Ca2+) trigger the release of acetylcholine, leading to sodium influx into the muscle fiber.
- Ca2+ binding to troponin exposes myosin-binding sites on actin.
- Myosin heads pull actin filaments toward the center of the sarcomere, causing contraction.
ATP and Muscle Contraction
- ATP is essential for muscle contractions, facilitating cross-bridge formation between myosin and actin.
- Energy is released when ATP is converted to ADP and inorganic phosphate (P).
- Rigor mortis occurs post-mortem when ATP is depleted, locking muscle fibers in contraction.
Muscle Fiber Types
-
Slow Twitch Fibers:
- Contract slowly, resist fatigue, and are utilized in endurance activities (e.g., long-distance running).
- Primarily use aerobic respiration and derive energy from fat; rich in myoglobin.
-
Fast Twitch Fibers:
- Contract quickly and fatigue rapidly; suited for vigorous, short bursts of activity (e.g., sprinting).
- Rely on anaerobic respiration for energy from glycogen; less myoglobin leads to paler muscle color.
Muscle Terminology and Nomenclature
- Origin: Non-movable attachment of a muscle.
- Insertion: Movable attachment of a muscle.
- Belly: Central part of the muscle.
- Muscles are named based on location, origin/insertion, size, shape, or function.
Muscles of Head and Neck
-
Facial Expression:
- Occipitofrontalis: Elevates eyebrows.
- Orbicularis oculi: Facilitates blinking.
- Zygomaticus: Responsible for smiling.
-
Mastication:
- Masseter: Primary muscle for chewing.
Tongue and Swallowing Muscles
- Intrinsic Muscles: Change tongue shape, located within the tongue.
- Extrinsic Muscles: Move the tongue, originating from surrounding bones.
- Suprahyoid and Infrahyoid Muscles: Stabilize or elevate/depress the hyoid bone, crucial for swallowing.
Thoracic and Abdominal Wall Muscles
-
Thoracic Muscles:
- External intercostals: Elevate ribs for inhalation.
- Internal intercostals: Depress ribs during forced exhalation.
- Diaphragm: Main muscle for quiet breathing.
-
Abdominal Wall Muscles:
- Rectus abdominis: Compresses the abdomen.
- External and internal abdominal obliques, transverse abdominis: Assist in abdominal compression.
Studying That Suits You
Use AI to generate personalized quizzes and flashcards to suit your learning preferences.
Description
Test your knowledge on muscle structure, function, and the physiology of the neuromuscular junction. This quiz covers critical topics such as the sliding filament model and the mechanisms of action potentials. Understand how muscle fibers communicate with motor neurons to facilitate movement.
