Chapter 9: Muscular System
Match each facial muscle with the arrow that points to it.
a. masseter b. orbicularis oculi c. orbicularis oris d. platysma e. sternocleidomastoid
Use the diagram of the anterior shoulder and arm to match the letters to the muscles they indicate.
a. subscapularis b. coracobrachiallis c. biceps brachii d. deltiod
During excitation of a muscle fiber, which one of the following events comes immediately after the release of acetylcholine from the motor neuron?
acetylcholine diffuses across the synaptic cleft
The process of a neuron, its axon, conducts electrical impulses called (blank) (blank) towards the end of the axon that innervates a target cell.
action potentials
A muscle that functions to cause action is referred to as the ______.
agonist
The process of glycolysis is ______.
anaerobic
Glycolysis is used to produce ATP for muscle contraction and is best described as ______.
anaerobic breakdown of glucose to produce ATP
Contraction of muscles of the ______ group of the thigh is primarily responsible for flexion of the thigh at the hip.
anterior
Muscles that move the thigh at the hip joint are classified into three groups based on their location. The psoas major and the iliacus are members of the (blank) group.
anterior
The flexors of the hand are located on the ______ side of the forearm.
anterior
What is the name of the process on a neuron that carries electrical impulses toward the cell to be stimulated?
axon
flexion
biceps brachii brachioradialis
Muscles of the ______ muscle group flex the knee and those of the ______ muscle group extend the knee.
hamstrings; quadriceps femoris
Muscle contractions generate ______, which is important for the overall functioning of the body.
heat
What type of contraction is observed when a muscle shortens?
isotonic
The muscles of mastication include the medial and lateral pterygoid,(blank) and (blank) .
masseter;temporalis
The masseter, the temporalis, and the two pterygoid muscles are the four muscles responsible for ______.
mastication
In order for muscles to move the thigh, they need to have attachments (origins and insertions) at what two areas?
pelvic girdle femur
Muscles that move the thigh are attached to the (blank) girdle and the (blank)
pelvic; femur
Muscles that move the thigh are attached to the (blank) girdle and the (blank) .
pelvic;femur
Contraction of muscles of the ______ group of the thigh can result in extension, abduction, or rotation of the thigh.
posterior
Where are the extensors of the hand located?
posterior side of forearm
A single muscle acts to extend the elbow joint. This muscle is located on the ______.
posterior surface of the humerus
The gluteus maximus and piriformis are part of the ______ group of muscles that move the thigh. The pectineus and gracilis are part of the ______ group.
posterior; medial
on this diagram of the shoulder and arm, the arrow indicates the (blank) muscle
subscapularis
When a muscle fiber is stimulated at a high enough frequency that it doesn't have time to relax, the forces of the individual twitches combine. What is this process called?
summation
When the frequency of stimulation of a muscle fiber increases, eventually the individual twitches combine by the process of (blank) which results in a sustained contraction.
summation
rotation
supinator pronator quadratus
What four pairs of muscles are considered muscles of mastication?
temporalis masseter lateral pterygoid medial pterygoid
What is the meaning of the term threshold stimulus?
the minimum strength of an electrical impulse that can stimulate contraction in an isolated muscle fiber
Categorize the muscles that move the thigh, indicating whether each is found on the anterior, posterior, or medial group of the muscles.
Medial group: - adductor longus, adductor magnus, gracilis Posterior Group: - gluteus maximus, gluteus medius, tensor fasciae latae Anterior Group: - psoas major, iliacus
To move the foot upwards towards the shin is known as (blank) . To turn the sole of the foot medially is known as (blank)
dorsiflexion; inversion
When is lactic acid produced?
during anaerobic metabolism
How many myofibrils and sarcomeres are found in a muscle fiber?
each muscle fiber contains many myofibrils, each made of many sarcomeres joined end to end
What type of muscle cells lack striations?
smooth muscle
Which type of muscle can change length without changing tautness?
smooth muscle
List the four components of a lever.
- Object to move - Force - Rigid bar or rod - Pivot point
Choose all characteristics of slow-twitch fibers.
- They are also called red fibers. - They contain large amounts of myoglobin. - They are well supplied with capillaries and mitochondria.
Indicate three characteristics of cardiac muscle.
-cells have large transverse tubules -single nucleus -cells have abundant mitochondria
Place the following steps of excitation-contraction coupling in order.
1. calcium is released from the sarcoplasmic reticulum 2. calcium binds to troponin 3. troponin changes shape and alters the position of tropomyosin 4. binding sites on actin filaments are exposed 5. myosin heads bind to actin
List in order the events leading to excitation of a muscle fiber.
1. nerve impulse arrives at a distal end of the axon 2. acetylcholine is released. 3. acetylcholine diffuses across the synaptic cleft 4. acetylcholine binds to its receptors on the muscle fiber sarcolemma 5. the permeability of sarcolemma to sodium ions increases
Place in order the steps leading to the relaxation of the muscle.
1. the nerve signal ceases 2. acetylcholine released into the synaptic cleft stops ACh already in the synaptic cleft is broken down 3. calcium is actively transported into the sarcoplasmic reticulum and Ca+2 diffuses away from troponin 4. troponin returns to its relaxed configuration, causing tropomyosin to cover the myosin binding sites on actin
Match the three groups of muscles that move the thigh to the type of movement produced at the hip joint.
Anterior group: - primarily flexes the hip Posterior group: - primarily extends the hip and abducts or rotates the thigh Medial Group: - primarily adducts the thigh
Match the action of the foot with the description.
Dorsiflexion - Move the foot upwards Plantar flexion - Move the foot downward Inversion - Turn the sole of the foot medially Eversion - Turn the sole of the foot laterally
True or false: Myofilaments shorten during contraction.
False
Choose all characteristics of smooth muscle cells.
They are not striated. They have a single nucleus. Their sarcoplasmic reticula are not well developed.
True or false: Muscles tend to atrophy with age.
True
A sarcomere extends from one ______ to the next.
Z line
What is an isotonic contraction?
a muscle changes in length, but its tension stays constant
A skeletal muscle fiber is ______.
a single muscle cell
Match each letter with the correct facial muscle.
a. epicranial aponeurosis b. frontalis c. occipitalis d. temporalis
Match the labels to the correct muscles in the anterior thigh
a. iliacus b. tensor fasciae latae c. pectineus d. vastus medialis
What are myofibrils?
bundles of proteins in a muscle cell
Which type of muscle have striated cells that form interconnected, branching, three-dimensional networks?
cardiac muscle
What are the three types of muscles found in the human body?
cardiac, smooth,skeletal
What is the first source of energy that is used to convert ADP to ATP after a contraction in a skeletal muscle cell begins?
creatine phosphate
By definition, what is muscle fatigue?
decreased ability of muscle to contract
A bundle of skeletal muscle fibers enclosed by a perimysium forms a(n) (blank) within a muscle.
fascicle
Muscle cells are also known as muscle fibers. In a skeletal muscle, muscle fibers are found as bundles called (blank) , each enclosed in a connective tissue sheath, called the (blank) .
fascicle; perimysium
Prolonged or intense exercise can lead to a condition called muscle (blank) , defined as the loss of a muscle's ability to contract.
fatigue
Due to their shape, muscle cells are also called muscle (blank)
fibers
What is the role of creatine phosphate during skeletal muscle contraction?
it is used to quickly regenerate ATP and ADP
Consider the naming of the temporalis muscle. What does the name tell you about the muscle?
it provides information about the locations of the origins and/or insertions for the muscles
Consider the naming of the triceps brachii muscle. What does the name tell you about the muscle?
it provides information about the number of heads (origins)
During high-intensity exercise, anaerobic metabolism results in the production of pyruvic acid, which is then converted to (blank) acid.
lactic
Which type of motor unit produces more force when recruited?
large motor unites (more muscles fibers)
A fulcrum, a force, and an object moved against resistance make up a ______.
lever
When a part of the body moves, the muscles and bones responsible for the movement act as a mechanical device known as a(n) (blank)
lever
Some abdominal muscles are attached to a band of connective tissue that extends from the xiphoid process of the sternum to the pubic symphysis called the (blank) (blank)
linea alba
Muscles with attachment points at the (1) pelvic girdle and (2) the femur will cause what type of movement?
movement of the thigh
Which statements correctly describe changes in a skeletal muscle cell during muscle contraction?
muscles shorten during contraction sarcomeres shorten during contraction myofilaments overlap during contraction
The sarcoplasm of a muscle fiber contains many parallel structures made of proteins. These structures are called ______.
myofibrils
What generates the force that shortens the sarcomeres to bring about muscle contraction?
myosin cross-bridges pulling on the actin filaments
What are the two major protein types found in myofibrils?
myosin; actin
Within myofibrils, thick filaments are composed of the protein (blank) , while thin filaments primarily contain (blank) .
myosin; actin
What is a motor unit composed of?
one motor neuron and all the muscle fibers it innervates
The end of a muscle that is fixed (relatively immovable) is called its ______.
origin
The point of attachment for a muscle that remains relatively stationary is its (blank)
origin
The trapezius, the rhomboid major and minor, and the levator scapulae are all muscles that move the (blank) girdle.
pectoral
The thigh muscle labeled as A is the ______ muscle. The muscle labeled as B is the ______ muscle.
psoas major; iliacus
Which of the following is a characteristic of slow-twitch (type I) fibers?
red in color
During which phase are calcium ions actively transported into the sarcoplasmic reticulum?
relaxation
Within myofibrils, the area between two successive Z lines is called a(n) ______.
sarcomere
Myofibrils are formed by many ______ positioned end-to-end.
sarcomeres
The (blank) are repeating units within muscle fibers that act as the functional units of muscle contraction.
sarcomeres
The membranous organelle within muscle fibers, called the (blank) reticulum, corresponds to the smooth endoplasmic reticulum of other cells.
sarcoplasmic
What is the name of the network of membranous channels that surrounds each myofibril within a muscle fiber?
sarcoplasmic reticulum
The knee is flexed by the action of the three muscles in the hamstring group, and the (blank) muscle.
sartorius
Compared to skeletal muscle, smooth muscle is ______ to contract and ______ to relax.
slower;slower
Which type of motor unit is more easily stimulated and, thus, is recruited first?
small motor units (fewer muscle fibers)
During muscle contraction, the sarcomeres shorten because ______.
thick and thin filaments slide past one another, increasing their overlap
In a muscle contraction, the force that shortens the sarcomeres comes from the myosin cross-bridges pulling on the (blank) filaments.
thin
When describing the roles of muscles in an action, what is the role of the agonist?
to cause an action
What is the function of the linea alba?
to provide attachment for abdominal muscles
Of the following muscles, which one moves the pectoral girdle?
trapezius
Which of the following are muscles that move the pectoral girdle?
trapezius rhomboid major serratus anterior levator scapula
extension
triceps brachii
In excitation-contraction coupling, the protein called (blank) moves to expose binding sites on the actin filaments that can form cross-bridges.
tropomyosin
During excitation-contraction coupling, calcium binds to ______.
troponin
True or false: Muscles generate heat when they contract.
true
True or false: Smooth muscle can maintain a forceful contraction longer than skeletal muscle.
true
When a single muscle fiber contracts when stimulated by a single impulse, the contractile response is called a(n) (blank).
twitch
A muscle response called a(n) (blank) consists of a period of contraction during which the fiber pulls at its attachment, followed by a period of (blank) during which the pulling force decreases.
twitch; relaxation
Muscle fibers with abundant mitochondria and myoglobin that are typically red in color are called ______ fibers.
type 1
For a typical muscle fiber in its optimal state, how many action potentials generated by a motor neuron must arrive at the neuromuscular junction to reach the threshold stimulus?
typically, a single action potential is enough to bring the muscle fiber to the threshold
A motor neuron and the muscle fibers that it controls constitute a motor (blank)
unit
The (blank) diaphragm is the deep layer of muscle at the pelvic outlet, serving to support the pelvic viscera.
urogenital
The ______ is part of the perineum and is located within the pubic arch.
urogenital diaphragm
On this diagram of the muscles in the thigh, the letter D indicates
vastus lateralis
Which three characteristics are signs of aging in the muscular system?
weak contractions slow reflexes atrophy
