KIN 474 Exam 1

What are the main divisions of the skeletal system? List what each includes.

• Axial: skull, vertebral column, ribs, and sternum

• Appendicular: shoulder girdle, bones of arms, wrist, hands, and pelvic girdle, bones of legs, ankles, and feet

What are the three different types of joints? List examples of each.

• Fibrous: sutures in the skull

• Cartilaginous: intervertebral discs 

• Synovial: elbow, knee

What is the structure and anatomy of skeletal muscle?

muscle, fascicle, muscle fiber, myofibril, myofilaments

What is a sarcomere?

A sarcomere is the smallest contractile unit on skeletal muscle. 

motor neuron

nerve cell

motor unit

motor neuron and the muscle fibers that it innervates

In relation to motor units (and its size), how does the extent of control of a muscle vary?

The extent of control of a muscle depends on the number of muscle fibers within each motor unit. Therefore, muscles that function with greater precision have motor units as few as one muscle fiber per motor neuron. Whereas bigger muscle groups like the quads, have more that hundreds of muscle fibers per motor neuron. 

What is the sliding filament theory?

states that the actin filaments at each end of the sarcomere slide inward on myosin filaments, pulling the z-lines toward the center of the sarcomere which shortens the muscle fiber.

SFT Resting phase

little calcium is present in the myofibril, so very few of the myosin cross bridges are bound to actin. The actin binding site is covered.

Excitation-contraction coupling

Calcium is released from the sarcoplasmic reticulum, and then it binds to troponin. This causes a shift in tropomyosin, so the myosin cross bridge can attach more rapidly to the actin filaments, allowing force to be produced as the actin filaments are pulled toward the center of the sarcomere. 

Contraction phase

With the myosin cross bridge being tightly bound to the actin filament first, ATP then binds to myosin, allowing it to release from the actin filament. ATPase on the myosin hydrolyzes the ATP to access energy, and the myosin head moves away from the actin filament. ADP and the phosphate molecule remain bound to myosin. The myosin head then binds to a new actin molecule. The myosin head release another phosphate which initiates the power stroke, pulling actin filament toward the center of the sarcomere. After, the myosin head releases ADP and returns to the ready state.

Recharge phase

Muscle shortening transpires only when this sequence of events occur– binding of calcium to troponin, coupling of the myosin cross-bridge with actin, power stroke, dissociation of actin and myosin, and resetting of the myosin head position. This occurs as long as the calcium is available, ATP is available and myosin ATPase is available. 

Relaxation phase

Stimulation of the motor nerve stops. Calcium is pumped back into the sarcoplasmic reticulum, which prevents the link between actin and myosin. 

What is the all-or-none principle?

All muscle fibers in the motor unit contract and develop force at the same time. Therefore, there is no such thing as a motor neuron stimulus that causes only some of the fibers to contract.

What is the length-tension relationship?

Each fiber has an optimal length to generate force. Optimal length occurs when there is optimal overlap of thick and thin filaments (maximizes cross-bridge interaction). When a sarcomere is fully stretched or completely shortened, little or no force can be developed

What are the different muscle fiber types and the main ways in which they differ?

• Type I: slow twitch, low force, fatigue resistant

• Type IIa: fast twitch, moderate force, fatigue resistant 

• Type IIx: fast twitch, high force, fast fatigue

proprioceptors

specialized sensory receptors that provide the central nervous system with information needed to maintain muscle tone and perform complex coordinated movements.

muscle spindles

a type of proprioceptor as when a muscle is stretched, deformation of the muscle spindle activates the sensory neuron, which sends an impulse to the spinal cord where it synapses with a motor neuron, causing the muscle to contract

golgi tendon organ

type of proprioceptor that are located within the tendon. They occur in a series with extrafusal muscle fibers. When an extremely heavy load is placed on the muscle, discharge of the GTO occurs. The sensory neuron of the GTO activates an inhibitory interneuron in the spinal cord, which in turn synapses with and inhibits a motor neuron serving the same muscle.

What is the direction of blood flow throughout the body?

Blood comes in through the right atrium and into the right ventricle and is pushed into the pulmonary artery in the lungs. After picking up oxygen, blood travels back into the heart through the pulmonary veins and into the left atrium, then left ventricle and exits the heart through the aorta.

What does it mean that the cardiovascular system is a "closed-circuit system"?

there are two systems that carry blood to and away from the heart. The arterial system carries blood away from the heart, whereas the venous system returns blood toward the heart. 

What is the pacemaker of the heart?

SA (sinoatrial) node is where rhythmic electrical impulses are normally initiated.

What is the difference in blood pressure between arteries and veins?

In arteries, the blood is pumped from the heart under a relatively high pressure, so they have strong muscular walls. In veins, the pressure is very low, so the walls are thin, but muscular.

How does the venous system return blood back to the heart?

Venules collect blood from the capillaries and gradually converge into the progressively larger veins, which transport blood back to the heart. 

What happens to alveolar pressure for inspiration and expiration to occur?

To cause inspiration, alveolar pressure must fall slightly below atmospheric pressure. During expiration, alveolar pressure must rise above atmospheric pressure. 

What is origin and insertion?

Origin is a muscle’s proximal attachment. Insertion is a muscle’s distal attachment

agonist

prime mover muscle

antagonist

a muscle that can slow down or stop the movement

synergist

a muscle that assists indirectly in a movement

first class lever

the muscle force and the resistive force are on opposite sides of the fulcrum (AXIS in the middle)

second class lever

the muscle force and the resistive force are on the same side of the fulcrum, with the muscle force acting through a moment arm longer than that through which the resistive force acts (RESISTANCE IN THE MIDDLE)

third class lever

the muscle force and the resistive force act on the same side of the fulcrum, with the muscle force acting through a moment arm shorter than that through which the resistive force acts (FORCE IN THE MIDDLE)

What is a mechanical advantage?

Greater than 1.0: a person can apply less force than the resistive force to produce an equal amount of torque

What is mechanical disadvantage?

Less than 1.0: a person must apply a much greater force than the amount of resistive force present, creating a disadvantage for the muscle.

How does tendon insertion affect force production and power?

A person whose tendons are inserted on the bone farther from the joint center should be able to lift heavier since the muscle force acts through a longer moment arm and thus could produce a greater torque around the joint. However, this is associated with a loss of maximum speed.

What is the relationship between force and velocity for a concentric contraction?

The force capability of a muscle declines as the velocity of a contraction increases. The relationship is not linear; the decline in force capability is steepest over the lower range of movement speeds. INVERSE RELATIONSHIP

What is the relationship between power and velocity for a concentric contraction?

Power is proportional to velocity

What are the planes of the body? What movements occur in each?

• Sagittal: flexion and extension

• Frontal: abduction and adduction

• Transverse: rotation

What is the optimal length of the sarcomere for force production?

Optimal cross bridge overlap

What is the angle of pennation?

angle between muscle fibers and an imaginary line between the muscle’s origin and insertion

How does angle of pennation affect force and power production?

Muscles that have a greater pennation have more sarcomeres in parallel and fewer sarcomeres in series, so they are better able to produce force but have a lower maximum shortening velocity than nonpennate muscles. Lesser amounts of pennation can cause a higher production of high velocities due to the greater number of sarcomeres in a row.

motor unit recruitment

Neural control affects the maximal force output of a muscle by determining which and how many motor units are involved in a muscle contraction

rate coding

the rate at which the motor units are fired

How does motor unit recruitment and rate coding affect strength?

Muscle force is greater when more motor units are involved in a contraction, the motor units are greater in size or the rate of firing is faster. Strength gains are due to these neural adaptations where your brain is learning how to generate more force from a given amount of contractile tissue.

Concentric muscle action

muscle shortens because the contractile force is greater than the resistive force. The forces generated within the muscle and acting to shorten it are greater than the external forces acting as its tendons to stretch it

eccentric muscle action

muscle lengthens because the contractile force is less than the resistive force. The forces generated within the muscle and acting to shorten it are less than the external forces acting at its tendons to stretch it

isometric muscle action

muscle length does not change because the contractile force is equal to the resistive force. The forces generated within the muscle and acting to shorten it are equal to the external forces acting at its tendons to stretch it

What are the different sources of resistance to muscle action?

gravity, inertia, friction, fluid resistance, elasticity

gravity

when the weight is horizontally closer to the joint, it exerts less resistive torque. When the weight is horizontally farther from a joint, it exerts more resistive torque

inertia

An object at rest or moving at a constant velocity will tend to continue in the same state of motion. Net forces are balanced. The force of gravity acts only downward, inertial force can act in any direction.

friction

resistive force encountered when one attempt to move an object while it is pressed against another object

fluid resistance

resistive force encountered by an object moving through a fluid, or by a fluid moving past or around an object or through an opening

elasticity

the more elastic component is stretch the greater the resistance  

What are the advantages and disadvantages of using weight machines?

• advantages: increased control over the direction and pattern of resistance, safety, design flexibility, ease of use 

• less accessible, more expensive 

What are the advantages and disadvantages of using free weights?

• advantages: whole-body training, simulation of real-life activities

  • disadvantages: less expensive, less control over the direction and pattern of resistance 

What is the strength-to-mass ratio?

• In sprinting and jumping, the ratio directly reflects an athlete’s ability to accelerate his or her body

• In sports involving weight classification, the ratio helps determine when strength is highest relative to that of other athletes in the weight class. 

• As body size increases, body mass increase more rapidly than does muscle strength 

• Given constant body proportions, the smaller athlete has a higher strength-to-mass ratio than does the larger athlete

What factors should you consider for resistance training regarding joint biomechanics?

• Back

• Intra-abdominal pressure 

• Lifting belts

• Shoulders

• Knees

• Elbows 

• Wrists 

phosphagen energy system

provides ATP for higher intensity activities which last for short periods of time. It replenishes ATP, and it occurs in the sarcoplasm.

How does the phosphagen system supply ATP?

hydrolyzes ATP and breaks down PCr. The phosphate group from PCr combines with ADP to restore ATP.

glycolysis

breaks down carbs. It does not replenish ATP as quickly as the phosphagen system. It also occurs in sarcoplasm.

How does glycolysis supply ATP?

Glycolysis breaks down carbohydrates (either glucose or glycogen) to resynthesize ATP.

oxidative system

most utilized at rest or during moments of low intensity activities, and it occurs in the mitochondria. 

How does the oxidative system supply ATP?

synthesizes ATP from fats and some from carbs.

Anaerobic system(s)?

They do not require oxygen. PHOSPHAGEN and GLYCOLYTIC system

Aerobic system(s)?

They require oxygen. KREB’S CYCLE and the rest of the OXIDATIVE SYSTEM

In which way (aerobic or anaerobic) can each of the food substrates (fat, carbohydrate, and protein) be broken down for energy?

Carbs are the only substrate that can be metabolized without oxygen. All substrates can be broken down for energy by aerobic systems. 

Which substrate is used primarily for low-intensity exercise and which is primarily used for high-intensity exercise?

• Low-intensity: fats

• High-intensity: carbs

Pyruvate may proceed in what two directions at the end of glycolysis?

It can either be converted to lactate in the sarcoplasm or transported to the mitochondria. If converted to lactate, ATP resynthesis quickly but not for long. When taken to the mitochondria, it resynthesizes slowly but for a much longer time at a low enough intensity. 

Cori cycle

The process of lactate being transported to the liver in the blood where it will then be converted to glucose. 

What is the Krebs cycle? Where does it occur in the cell?

When pyruvate is taken to the mitochondria instead of stored as lactate, it is converted to acetyl-CoA upon entry. Acetyl-CoA can then enter Krebs cycle to further resynthesize ATP.

What energy system produces ATP the fastest?

The phosphagen system is the fastest at producing ATP. However, it is not produced in enough quantities or replenished quickly enough to last throughout exercise.

which energy system has the greatest capacity to form ATP?

The oxidative system has the greatest capacity to form ATP  but requires oxygen and takes a longer amount of time to complete the cycle. 

What is the lactate threshold?

The max intensity where blood lactate begins to rapidly increase above its initial concentration. It represents a shift towards reliance on anaerobic mechanisms to meet energy needs.

How does high-intensity training affect lactate threshold?

High intensity training over time will cause lactate accumulation to occur later. This allows an athlete to perform with a higher O2 intake with less lactate accumulation.

What is oxygen deficit?

After exercise starts, both anaerobic and aerobic systems must be used because anaerobic systems do not produce ATP rapidly enough. This anaerobic energy added to the total energy used creates the oxygen deficit.

What is EPOC?

EPOC is the excess postexercise oxygen consumption or the oxygen debt. The oxygen levels post exercise are above resting values in order to replenish oxygen stores to the levels the body was at pre-exercise

factors responsible for EPOC

• Replenishment of oxygen stores 

• ATP/CP synthesis

• Increased body temperature, circulation, and ventilation

• Triglyceride-fatty acid cycling

• Protein turnover

  • Change of energy efficiency

What is metabolic acidosis?

exercise-induced decrease in pH and can possibly be held responsible for a majority of fatigue encountered during activity and exercise. It inhibits the turnover rate of enzymes within the exergy systems.

How much carbohydrate should be consumed following exercise to replenish glycogen stores?

At increasingly high intensities, muscle glycogen becomes more and more important for synthesizing energy. In some cases, a muscle cell’s entire glycogen store can be depleted. These stores can be replenished with 0.7-3.0g carbohydrates per kg body weight is ingested every 2 hours post exercising

What is interval training?

Interval training uses predetermined intervals of activities and periods of rest in order to allow for more efficient transfer of energy throughout the metabolic pathways. It places an emphasis on bioenergetic adaptations and provides the ability to work for higher intensities with less fatigue as opposed to continuous moderate intensity.

What is the exercise:rest ratio for the phosphagen system?

1:12 to 1:20

What is the exercise:rest ratio for the fast glycolytic system?

1:3 to 1:5

What is the exercise:rest ratio for the fast glycolytic- oxidative system?

1:3 to 1:4

What is the exercise:rest ratio for the oxidative system?

1:1 to 1:3

What is high-intensity interval training?

It is a type of interval training involving brief periods of high intensity exercise alternating with short recovery periods. It is very beneficial to cardiopulmonary, metabolic, and neuromuscular adaptations. Many consider it one of the most effective methods of improving physical performance. It provides stimulation for both oxidative muscle fiber adaptation as well as myocardial hypertrophy

What is combination training?

It is the addition of aerobic endurance training in order to enhance hypertrophy. It is also known as cross-training. If done incorrectly, it can prove to be harmful to anaerobic performance

Is combination training beneficial for the anaerobic athlete?

Anaerobic training can be beneficial to aerobic athletes. For example, runners who add strength training to their training greatly improve their performance. However, the opposite is not necessarily true as aerobic training can hinder performance in anaerobic athletes and is typically counterproductive. 

Which energy system requires the largest work-to-rest period ratio?

Fast glycolysis. This is because it is able to synthesize a decent amount of ATP in one cycle, but it takes a bit to replenish ATP stores.

Which energy system requires the smallest work-to-rest period ratio?

Phosphagen system. It produces a small amount of energy at a time but at a rapid rate. This cannot be continued for very long durations 

Which anatomical plane divides the body into left and right halves

sagittal

The ____ are located in the muscle belly

muscle spindles

What molecule must be released to activate actin filaments?

calcium

The sarcomere is the smallest contractile unit of the cell.

true

The size principle states the ___-threshold motor units are recruited first.

low

the size principle states that type II fibers are recruited first.

false

Type I muscle fibers have all of the characteristics except

high contraction speed

bradycardia is defined as a heart rate ___

below 60

The sinoatrial node is the pacemaker of the heart

true

tendon insertion farther from joint center increases the ability to produce ___

power

What type of muscle action occurs when the muscular force is less than the resistive force?

eccentric