Skeletal Muscles and Motor Output

Flashcards about Skeletal Muscles and Motor Output

What type of control does the somatic division have over skeletal muscles?

Voluntary (conscious) control

What type of control of reflexive skeletal muscle contractions?

Involuntary (unconscious) control

What is the Accommodation reflex?

Coordinated changes in the vergence and lens to focus on near objects.

What is the Acoustic reflex?

Contraction of the stapedius and tensor tympani muscles in the middle ear in response to high sound intensities.

What is the Ankle jerk reflex?

Jerking of the ankle when the Achilles tendon is hit with a tendon hammer while the foot is relaxed, stimulating the S1 reflex arc.

What is the Arthrokinetic reflex?

Muscular activation or inhibition in response to joint mobilization

What is the Asymmetric tonic neck reflex (ATNR)?

In infants up to four months of age, when the head is turned to the side, the arm on that side will straighten and the contralateral arm will bend.

What is the Babinski reflex?

In infants up to one year of age, and also in older individuals with neurological damage, a spreading of the toes and extension of the big toe in response to stroking the side of the foot.

What is the Baroreflex?

Homeostatic countereffect to a sudden elevation or reduction in blood pressure detected by the baroreceptors in the aortic arch, carotid sinuses, etc.

What is the Bezold-Jarisch reflex?

Involves a variety of cardiovascular and neurological processes which cause hypopnea and bradycardia.

What is the Biceps reflex?

A jerking of the forearm when the biceps brachii tendon is struck with a tendon hammer, stimulating the C5 and C6 reflex arcs.

What is the Corneal reflex?

Blinking of both eyes when the cornea of either eye is touched.

What is the Cough reflex?

A rapid expulsion of air from the lungs after sudden opening of the glottis, and usually following irritation of the trachea.

What is the Cremasteric reflex?

Elevation of the scrotum and testis elicited by stroking of the superior and medial part of the thigh.

What is the Crossed extensor reflex?

A contraction of a limb in response to ipsilateral pain, and extension of the contralateral limb.

What is the Diving reflex?

slowing of heart rate and constriction of peripheral vessels when submerged in water.

What is the Galant reflex?

A primitive reflex in infants up to four months of age, a rotation of the upper body towards one or other side of the back when that side is stroked.

What is the Hering–Breuer reflex?

A reflex triggered to prevent over-inflation of the lung

What is the Jaw jerk reflex?

A reflex in which the jaw closes suddenly when the mandible is tapped

What is the Knee jerk reflex?

A kick caused by striking the patellar tendon with a tendon hammer just below the patella, stimulating the L4 and L3 reflex arcs.

What is the Moro reflex?

A sudden symmetric spreading of the arms, then unspreading and crying, caused by an unexpected loud noise or the sensation of being dropped.

What is the Palmar grasp reflex?

In infants up to six months of age, a closing of the hand in response to an object being placed in it.

What is the Plantar reflex?

In infants up to 1 year of age, a curling of the toes when something rubs the ball of the foot.

What is the Pupillary accommodation reflex?

A reduction of pupil size in response to an object coming close to the eye.

What is the Pupillary light reflex?

A reduction of pupil size in response to light.

What is the Rooting reflex?

Turning of an infant's head toward anything that strokes the cheek or mouth.

What is the Sucking reflex?

A primitive reflex, sucking at anything that touches the roof of an infant's mouth.

What is the Triceps reflex?

Jerking of the forearm when the triceps tendon is hit with a tendon hammer, stimulating the C7 and C6 reflex arcs.

What is the Vagovagal reflex?

Contraction of muscles in the gastrointestinal tract in response to distension of the tract following consumption of food and drink.

What is the Vestibulo-ocular reflex?

Movement of the eyes to the right when the head is rotated to the left, and vice versa.

What is the main function of muscles?

Muscles only contract (shorten) forcefully

What are myofibrils?

Long, cylindrical protein bundles that fill myofiber cells

What is the function of sarcoplasmic reticulum?

Stores Ca++

What are Sarcomeres?

Contractile units of muscles

What is the role of acetylcholine at the neuromuscular junction?

Motor neuron releases acetylcholine at the neuromuscular junction via exocytosis

What happens when acetylcholine binds to its receptor?

Acetylcholine receptor opens channel when acetylcholine binds; Na+ enters the channel

What triggers the release of Ca2+ from the sarcoplasmic reticulum?

The electrical impulse triggers the release of Ca2+ from the sarcoplasmic reticulum.

What is the sliding filament theory?

Muscle contraction mechanism involving actin and myosin

What is the role of ATP in muscle contraction?

It causes the myosin head to detach from actin.

What are the three energy molecules stored within muscle cells/tissue?

ATP, Creatine, Glycogen

What are the features of Slow-twitch (Type I) muscle fibers?

small diameter fiber cells that can contract incrementally for a relatively long time, abundant blood supply, high concentrations of mitochondria, can temporarily store oxygen, predominate muscles that are active for long periods (endurance)

What are the features of Fast-twitch (type II) muscle fibers?

large diameter fibers, split ATP rapidly for short bursts of contraction, less blood supply, cannot sustain contractions for long, break down ATP rapidly, capable of anaerobic metabolism

What is Hypertrophy?

The more stress (resistance) placed on muscle fibers, the more they will adapt by increasing their myofibril content

What is Atrophy?

Wasting away of muscles, breakdown of myofibril content and lack of myofibril production

What is muscle thermoregulation?

Skeletal muscles can also be utilized for thermoregulation, the maintenance of internal body temperature, when the body temperature drops below a certain threshold