Human Body in Health and Illness Chapter 9

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Questions and Answers

What is the role of the epimysium in muscle tissue?

Covers individual muscle fibers

Surrounds fascicles of muscle fibers

Attaches muscle to bone

Surrounds the entire muscle (correct)

What is the correct sequence of structures from largest to smallest within a muscle?

Sarcomere, myofibril, muscle fiber, fascicle

Fascicle, muscle fiber, myofibril, sarcomere (correct)

Muscle fiber, fascicle, myofibril, sarcomere

Muscle fiber, myofibril, sarcomere, fascicle

Which of the following statements accurately describes the sliding filament mechanism of muscle contraction?

Actin filaments shorten, pulling myosin filaments towards the center of the sarcomere

Myosin filaments slide past actin filaments, causing the sarcomere to lengthen

Actin filaments slide past myosin filaments, causing the sarcomere to shorten (correct)

Myosin filaments shorten, pulling actin filaments towards the center of the sarcomere

Which of the following is NOT a direct requirement for muscle contraction?

Sodium ions Signup and view all the answers

What is the role of the sarcoplasmic reticulum in muscle contraction?

Stores and releases calcium ions Signup and view all the answers

Which of the following best describes the relationship between a motor neuron and a muscle fiber?

One motor neuron innervates many muscle fibers Signup and view all the answers

What is the primary function of the tendon?

To attach muscle to bone Signup and view all the answers

Which of the following statements best describes the role of troponin and tropomyosin in muscle contraction?

They regulate the interaction between actin and myosin Signup and view all the answers

Which muscle is responsible for flexing the forearm at the elbow?

Biceps brachii Signup and view all the answers

Which muscle is located in the neck and helps us to rotate our head?

Sternocleidomastoid Signup and view all the answers

Which of the following is an example of how muscles are named based on their location?

Pectoralis major Signup and view all the answers

Which type of muscle contraction is characterized by a sustained contraction caused by repeated stimulation?

Tetanus Signup and view all the answers

Which of the following muscles is responsible for closing the eyes?

Orbicularis oculi Signup and view all the answers

What is the term for the type of muscle atrophy that occurs due to lack of nerve stimulation?

Denervation atrophy Signup and view all the answers

Which of the following is NOT an energy source for muscle contraction?

Lactic acid fermentation Signup and view all the answers

Which muscle assists in extending the leg at the knee joint?

Quadriceps femoris Signup and view all the answers

What is the role of calcium in muscle relaxation?

Calcium returns to the sarcoplasmic reticulum, reducing its concentration in the sarcoplasm. Signup and view all the answers

What is the role of the motor unit in muscle contraction?

The motor unit controls the number of muscle fibers activated to generate force. Signup and view all the answers

What distinguishes myasthenia gravis from curare poisoning?

Myasthenia gravis is an autoimmune disorder, while curare poisoning is caused by a toxin. Signup and view all the answers

Which of the following statements accurately describes the sequence of events leading to muscle contraction?

Nerve impulse → acetylcholine release → muscle fiber depolarization → calcium release → actin-myosin interaction. Signup and view all the answers

What is the difference between a twitch and tetanus?

A twitch is a single, brief contraction, while tetanus is a sustained, forceful contraction. Signup and view all the answers

Which of these is NOT a source of energy for muscle contraction?

Lactic acid Signup and view all the answers

What is the function of the neuromuscular junction?

It acts as a synapse where the motor neuron communicates with the muscle fiber. Signup and view all the answers

Which of the following disorders involves abnormalities in the neuromuscular junction?

Myasthenia gravis Signup and view all the answers

Which of the following muscles is part of the abdominal wall?

Transversus abdominis Signup and view all the answers

Which muscle group includes the iliopsoas?

Muscles of the Thigh Signup and view all the answers

Which of the following muscles is responsible for flexion of the forearm?

Brachialis Signup and view all the answers

What is not classified as a muscle of the shoulder girdle?

Biceps brachii Signup and view all the answers

Which of the following muscles is involved in the extension of the knee?

Quadriceps femoris Signup and view all the answers

Which muscle group contributes to the flexion of the fingers?

Flexor digitorum Signup and view all the answers

Which muscle is part of the calf region responsible for plantar flexion?

Gastrocnemius Signup and view all the answers

The rotator cuff muscles primarily stabilize which joint?

Shoulder joint Signup and view all the answers

Study Notes

Lesson Plan

The document is a lesson plan manual for Herlihy's The Human Body in Health and Illness, 6th edition.
The specific chapter is Chapter 9, Muscular System.

Lesson 9.1

The lesson covers the types, functions, and structure of muscles.
Key learning objectives include identifying muscle tissue types, comparing whole muscle and single fiber structures, describing the sliding filament mechanism of muscle contraction, explaining the role of calcium and ATP in contraction, and describing the relationship between skeletal muscles, nerves, motor units, and the neuromuscular junction.

Types and Functions of Muscles

Skeletal muscle
Smooth muscle
Cardiac muscle

Three Types of Muscles

Cellular appearance is different for each type.
Location varies; skeletal muscle is overlying the skeleton, smooth is in organs/viscera, and cardiac in the heart
Different types are classified as; striated voluntary or non-striated involuntary

Layers of Connective Tissue

Fascia consists of epimysium (whole muscle), perimysium (surrounding fascicles), and endomysium (surrounding individual muscle fibers)
Fascicles form bundles of muscle fibers.
Tendon connects muscles to bones.
The whole muscle, fascicles, and tendons form a muscle unit.

Muscle Attachments

Tendons attach muscle to bone.
Muscles can attach directly to bone or soft tissue.
Aponeurosis connects muscle to muscle or muscle to bones.

Muscle Fiber: Cell

The myofibril is made of sarcomeres
Sarcoplasmic reticulum
Sarcolemma
T-tubule system

Sarcomeres: Structure

From Z-line to Z-line is a single sarcomere.
Thin filaments are actin, tropomyosin, and troponin.
Thick filaments are myosin.
Sarcomeres contract when the thin and thick filaments slide past each other.

Sliding Filament Mechanism

Myosin heads make contact with actin.
Myosin heads rotate, pulling actin towards the center of the sarcomere.
Sarcomere shortens, causing muscle contraction.

Role of Calcium and ATP

Calcium is stored in the sarcoplasmic reticulum.
During stimulation, calcium is released, allowing actin, myosin, and ATP to interact, causing muscle contraction.
Calcium then returns to the sarcoplasmic reticulum for muscle relaxation.

Somatic Motor Neuron Stimulation

Skeletal muscle contracts when stimulated by a somatic motor nerve.
The impulse travels from the spinal cord to the muscle.
The electrical impulse diffuses across the neuromuscular junction.
Causes the release of neurotransmitter Acetylcholine.
Acetylcholine diffuses across the junction and attaches to receptor sites.
Muscles contracts with stimulation.
Muscle relaxes when calcium is pumped back to the sarcoplasmic reticulum

The Motor Unit

Individual muscle fibers have an "all or nothing" response while the whole muscle can vary the force of contraction.
This is due to motor units and recruitment.

Innervation of a Skeletal Muscle

Somatic motor nerves innervate skeletal muscles
Motor units include nerves and the muscles they innervate.

The Neuromuscular Junction

The space between the motor neuron and muscle fiber.
Where neurotransmitter acetylcholine does its work.

Steps of Information Transfer

Neuron stimulation.
Vesicles move and fuse with the membrane.
ACh diffuses and attaches to receptor sites.
ACh stimulates receptors, causing electrical impulses

Impairment at the NMJ

Myasthenia gravis.
Curare.
Neurotoxins, specifically Clostridium tetani (tetanus) and Clostridium botulinum (botulism and Botox).

Disorders of the NMJ

Various disorders can impair the neuromuscular junction. This includes myasthenia gravis, curare, and clostridium botulinum which can block the neurotransmitter release.

Muscular Contractions and Actions

Discuss single fiber, twitch and tetanus
Identify energy sources for contraction, like metabolism of creatinine phosphate, glycolysis, and aerobic metabolism
Trace the sequence of muscle contraction from nerve stimulation and explain how it works.
Define muscle terms and state the basis for naming muscles in the body.
Identify and List the actions of the major muscles.

Muscle Responses

Twitch: Single, brief muscle response. The muscle contracts and then fully relaxes.
Tetanus: Sustained muscle contraction caused by repeated stimulation
Tonus: Normal, continuous state of partial muscle contraction

Energy Sources for Contraction

Metabolism of creatinine phosphate.
Glycolysis (anaerobic metabolism).
Aerobic metabolism

Muscle Terms

Origin
Insertion
Prime mover
Synergist
Antagonist

Muscle Overuse and Underuse Terms

Hypertrophy: Growth in response to overuse.
Atrophy: Wasting (disuse, denervation, senile)
Contracture: Abnormal fibrous formation in muscle.

How Skeletal Muscles Are Named

Size (Gluteus maximus)
Shape (Trapezius)
Orientation of fibers (Rectus abdominis)
Location (Pectoralis)
Number of origins (Biceps)
Origin and insertion (Sternocleidomastoid)
Muscle action (Adductors)

Major Muscles

The text provides a list of muscles and their descriptions (the anatomical illustration). This includes facial, neck, trunk, shoulder, forearm, wrist, hand & fingers, thigh and the leg/foot muscles.

Special Muscles

A selection of special muscles and their functions are shown (pictures and their names). This spans from the lotus position to the praying muscle (sternocleidomastoid).

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Description

This lesson covers Chapter 9 of Herlihy's The Human Body in Health and Illness, focusing on the muscular system. Students will explore the types, functions, and structures of skeletal, smooth, and cardiac muscles. Key learning objectives include understanding the sliding filament mechanism and the role of calcium and ATP in muscle contraction.