Chapter 6 Review Flashcards
How do cells of the three types of muscle tissues differ from one another anatomically?
Skeletal muscle fibers are long multi-nucleate cells with striations. Cardiac cells are branching, typically uni-nucleate cells with less striations. Smooth muscle cells are spindle shaped, uni-nucleate and non-striated.
Which muscle type has the most elaborate connective tissue wrappings?
Skeletal
What does striated mean relative to muscle cells?
Striped or having bands
How do the movements provided by skeletal muscle differ from those promoted by smooth or cardiac muscle?
Skeletal muscle movements can be very forceful & rapid , whereas smooth muscle movements tend to be slow and rhythmic.
Structures of the skeletal muscle from smallest to largest.
Myofilament, sarcomere, myofibril, muscle fiber (cell), fascicle.
Structures from smallest to largest + functions.
Endomysium - wraps each muscle fiber (or muscle cell)
Perimysium - wraps around a fascicle
Epimysium - wraps entire muscle (many groups of fascicles)
Which type of muscle tissue has involuntary regulation of contraction?
Cardiac and smooth
What is the plasma membrane of a muscle cell called?
Sarcolemma
What are the 4 main functions of muscles?
Produce movement
Maintain posture and body position
Stabilize joints
Generate heat
What is a sarcomere?
Tiny contractile units, which are the structural & functional units of skeletal muscles.
What is a myofibril?
Long, ribbon-like organelles that nearly fill the cytoplasm, composed of bundles of myofilaments.
I band
Light band
A band
Dark band
Z disc
Mid-line interrupter of the I band
H zone
Lighter central area of the A band
M line
Center of the H line
What structure(s) is/are responsible for the banding pattern in skeletal muscle cells?
The alignment of the bands on the myofilaments (actin=light) (myosin=dark)
What is the name of the neurotransmitter that stimulates skeletal muscle fibers?
Acetylcholine (ACh)
What is the gap between the nerve endings and the muscle fiber called?
Synaptic cleft
Neuromuscular junction
A nerve impulse reaches the axon terminal of a motor neuron. CA2+ channels open and calcium enters the axon terminal. Calcium entry causes vesicles to release their contents (ach) via exocytosis. ACH diffused into the synaptic cleft & binds to receptors (voltage-gated channels) in the sarcolemma (muscle cell membrane) opening them. This opening of the voltage-gated channels causes the simultaneous passage of NA+ into the muscle and K+ our of the muscle. This change in electrical conditions (depolarization) leads to a second action potential which is propagated down the T tubules. This causes calcium to be released by the endoplasmic reticulum onto the filaments. Calcium binds to troponin causing tropomyosin to slide out of the binding sites on actin. Charged Myosin heads bind to actin causing a power stroke. (The sliding of actin). A new molecule of ADP re-charges the myosin heads allowing them to unbind and move back into position. Enzymes break down ACH in the synaptic cleft and calcium is reabsorbed into the sarcoplasmic reticulum causing the muscle to relax.
What is the role of calcium ions during skeletal muscle contraction?
Calcium enters the axon terminal causing the release of acetylcholine and it also is released by the sarcoplasmic reticulum causing the release of tropomyosing from the actin binding sites.
Which ions enter the muscle during the generation of an action potential?
Sodium
Which chemical triggers sliding of the muscle filaments?
Calcium
What is the direct source of energy used by muscle fibers for contraction?
Stored ATP
Origin
a muscle fixed point that does note move
Insertion
the place of attachment that causes the movement of a bone
Which is a cross-bridge attachment more similar to: a synchronized rowing team or a person pulling a bucket on a rope out of a well?
Pulling a bucket out of a well
Flexion
decreasing the angle between two bones
Extension
increasing the angle between two bones (straightening a bend)
Adduction
movement of a body part towards the body’s midline
Abduction
the movement of a body part away from the bodys midline
Prime mover
the main muscle that causes a movement to occur. Ex: bicep (elbow flexion)
Antagonist
the muscle that does the opposite movement of the prime mover (is relaxed while the prime mover is contracted) Ex: tricep (elbow extension)
Synergist
muscle that moves in conjunction with the prime mover. Ex: brachialis aids in elbow flexion
Fixator
stabilizies the joints /prevents rotaion. Ex: muscles that make up the shoulder girdle
Frontalis
Frontal bone that raises the eyebrows
Orbicularis Oris
circular muscle that surrounds the lips and causes them to protrude or pucker
Orbicularis Oculi
circular muscle that surrounds the eyes and allows the eyelid to blink
Buccinator
deep cheek muscle that depreses the cheeks
Zygomaticus
located from the zygomatic bone and inserts into the corners of the mouth and pulls it up superiorly
Masseter
large chewing muscle (the stronger the masseter the stronger the bite)
Temporalis
assist in chewing
Platysma
large muscle that originates at the top of the chest and inserts into the bottom of the jaw. Draws down the skin around the lower part of the mouth.
Sternocleidomastoid
paired on the left and the right of the neck that allows the head to rotate to opposite sides
Pectoralis Major
superficial muscle that comprises the anterior chest. Functions to adduct or depress the arm
Trapezius
trapezoid or diamond shaped muscle that covers the superficial portion of the back. Extends from the occipital bone to the lower thoracic vertebrae of the spine . it moves the scapula and supports the arm
Latissimus Dorsi
occupies the majority of the lower posterior thorax. Primary function is to adduct, medially rotate and extend the arm.
Erector Spinae
Deep posterior spinal muscles that lie alongside the the cervical, thoracic and lumbar vertebrae. Function to straighten the back and move side to side.
Deltoid
shoulder muscle that stabilizes the shoulder joint
Biceps brachii
Anterior & super portion of the arm.
prime mover of elbow flexion
Brachialis
synergistic to and deep to the biceps brachii, extending across the antecubital region.
Brachioradialis
primarily acts as a flexor of the elbow. Also stabilizes the forarm
Triceps brachii
Superior & posterior arm. Antagonist to the biceps brachii
Gluteus medius
superficial gluteal muscle
Gluteus maximus
deep to the gluteus maximus. Injection point
Iliopsoas
Deep to the pelvis
Hamstring group
The semitendinosus, semimembranosus, and biceps femoris muscles comprise the hamstring muscle group.
Sartorius
Superficial to the hamstring group and runs obliquely across the thigh.
Quadriceps Group
Anterior thigh muscle group
Rectus femoris, Vastus medialis, vastus intermedialis, and vastus lateralis
Gastrocnemius
two bellied calf muscle (allows us to stand on our toes)
Soleus
large muscle on the back of your lower leg but deep to the gastrocnemius. Can be seen lower near the heal.
What is myasthenia gravis? How is this different from the effects of botox on muscles?
Myasthenia gravis is a rare but long-term condition that causes muscle weakness. Caused by an interruption at the neuromuscular junction where the immune system has damaged the receptors that ACH binds to. Botox on the other hand prevents ACH from being released by the vesicles. The receptors on the sarcolemma are not affected.
