BIO 130 Exam 4

Terms	Definitions
A motor unit is a motor neuron and all of the muscle fibers that it innervates, or stimulates.	What is a motor unit?
A muscle is composed of several motor units, but they don't have to all contract at the same time, thus muscles can "partially contract".	How do motor units relate to muscles?
Motor units can be from around 3 muscle fibers, like in the extrinsic eye muscles, to around 180 muscle fibers, like in the soleus, to around 1-2000 fibers, like in the gastrocnemius.	How big can motor units be?
Muscles generally have a mixture of small to large motor units, they are often not just one size.	Do muscles only contain one size of motor units?
A muscle twitch is the contraction response to a single, brief stimulus.	What is a muscle twitch?
First there is a latent phase/lag phase as muscle do not instantly contract when we tell them to. Secondly there is the contraction phase, which lasts as long as the Ach lasts. Finally there is the relaxation phase, which is where the unit calms down.	What is the time course of a twitch contraction?
A threshold stimulus is the weakest stimulus capable of generating a response from the smallest motor unit.	What is a "threshold stimulus"?
A sub-threshold stimulus is a stimulus that is below the threshold of the smallest motor unit such that no motor units contract.	What is a "sub-threshold stimulus"?
A sub-maximal stimulus is a stimulus that can cause the contraction of several motor units in the gross muscle, but that does not cause the contraction of all the motor units.	What is a "sub-maximal stimulus"?
Basically, the larger the stimulus the more units are "recruited." It is not that they contract any more, it is simply more units contracting. Thus, there is a step-wise increase in contraction force seeing as the relationship between stimulus strength and units recruited is almost linear.	How does the concept of "recruitment" work for motor units?
A maximal stimulus is the smallest stimulus that will cause the contraction of all motor units.	What is a "maximal stimulus"?
A supramaximal stimulus is a stimulus that is stronger than the maximal stimulus that does not increase contraction strength since all motor units are already recruited, thus not making the contraction any stronger.	What is a "supramaximal stimulus"?
Muscle twitches arises from low frequency stimuli whereas tetanus is from high frequency stimulation.	What is the difference in frequency levels between a muscle twitch and tetanus?
Tetanus is smooth, sustained muscle contraction caused by high-frequency stimulation.	What is tetanus?
It is when the contraction force is maintained between stimuli.	What is fusion?
This is when the peak contraction force increases above that of a twitch contraction.	What is summation?
It is when there is an increase in stimulus frequency, though only to a moderate frequency, thus the muscle fiber is not allowed to relax completely between stimuli. This results in incomplete fusion and only some summation.	What is "incomplete tetanus"?
It is when there is a high frequency stimuli, high enough that no relaxation occurs between stimuli. This results in complete fusion and maximal summation.	What is "complete tetanus"?
They are located in the forearm, but their tendons are in the hand.	Where are the extrinsic muscles of the hand located?
They are located in the hand.	Where are the intrinsic muscles of the hand located?
There is a lot of fascia.	How much fascia is there in the hand?
They are, in general, very long.	How long are the tendons of the muscles of the hand?
They are connective tissue sheaths that are meant to hold the tendons together, and there are many of them in the hand.	What are "tendon sheaths"?
The median nerve innervates the anterior forearm muscles and the ulnar nerve innervates mainly muscles in the hand.	What two nerves innervate the hand muscles?
The medial epicondyle of the humerus.	Where does the flexor carpi radialis originate?
On the base of the 2nd and 3rd metacarpals.	Where does the flexor carpi radialis insert?
It aids in wrist flexion and wrist abduction, which is rotating the wrist towards the thumb.	What does the flexor carpialis muscle do?
Flexor Carpi Radialis
The medial epicondyle of the humerus and the olecranon process of the ulna.	Where does the flexor carpi ulnaris originate?
The base of the 5th metacarpal.	Where does the flexor carpi ulnaris insert?
It aids in wrist flexion and wrist adduction, which is rotating the wrist towards the pinky.	What does the flexor carpi ulnaris do?
Flexor Carpi Ulnaris
Medial epicondyle of the humerus and the olecranon process of the ulna.	Where does the pronator teres originate?
The lateral radius.	Where does the pronator teres insert?
It aids in forearm pronation and elbow flexion, though it is very weak concerning elbow flexion.	What does the pronator teres do?
Pronator Teres
On the medial epicondyle of the humerus.	Where does the palmaris longus originate?
On the palmar aponeurosis and the skin/fascia of the palm.	Where does the palmaris longus insert?
It aids in hand flexion and tenses skin and fascia of palm during hand movements, though not everyone has this.	What does the palmaris longus do?
Palmaris Longus
The distal, lateral part of the humerus.	Where does the Extensor Carpi Radialis Longus originate?
On the base of the 2nd metacarpal	Where does the Extensor Carpi Radialis Longus insert?
It aids in wrist extension and wrist abduction.	What does the Extensor Carpi Radialis Longus do?
Extensor Carpi Radialis
The lateral epicondyle of the humerus, and on the proximal ulna.	Where does the Extensor Carpi Ulnaris originate?
On the base of the 5th metacarpal.	Where does the Extensor Carpi Ulnaris insert?
It helps with wrist extension and with wrist adduction.	What does the Extensor Carpi Ulnaris do?
Extensor Carpi Ulnaris
On the lateral epicondyle of the humerus	Where does the Extensor Digitorum originate?
On the distal phalanges of fingers 2-5	Where does the Extensor Digitorum insert?
It aids in finger extension.	What does the Extensor Digitorum do?
Extensor Digitorum
It is very little tension as there is too little room for the myosin to contract.	What happens to the potential tension of a very short sarcomere?
There is not enough overlap for the myosin to contract.	What happens to the potential tension of a very long sarcomere?
There is an optimal muscle length where there is enough overlap for the sarcomere to contract but not too much that there is no room to contract.	When is there the most tension strength in regards to sarcomere length?
The lighter the load, the higher the velocity. If the load gets too high, though, there can be negative velocity and the muscles can lengthen.	How does contraction velocity relate to the load of the contraction?
It is the perception of tiredness, it is like a warning saying that we are hitting the limits of our body.	What is psychological fatigue?
It is mainly common in well-trained athletes, and it is when muscles run out of glucose. This is pushing muscles to their absolute limits.	What is muscular fatigue?
This is generally disease-related, but it happens when we run out of Ach.	What is synaptic fatigue?
Muscle tone, when muscles are maintained in a partial contraction state, helps keep muscles ready such that the sarcomeres are kept at the optimal length, it helps keep our posture, and helps protect our joints and stabilize them.	Why is muscle tone so important?
It is a contraction where the muscles do not shorten in length, but the force remains the same or increases.	What is Isometric contraction?
This is when the force remains the same, but the muscle length changes.	What is Isotonic contraction?
This is what we normally think of when we think of "contraction," as it is shortening contraction that does some work.	What is Concentric Contraction?
This is when there is lengthening of muscle but we maintain the same force, like when we walk up or down stairs.	What is Eccentric Contraction?
Eccentric Contraction can generate around 50% more force, but it is related to "delayed onset muscle soreness", which is basically when your muscles hurt today from overworking them the day before.	What are the advantages and disadvantages of Eccentric Contraction?
Trapeius, Levator Scapulae, Rhomboids, Serratus Anterior, and Pectoralis Minor	What are the main fixators of the scapula?
Levator Scapulae and Trapezius (upper fibers), They help elevate the scapula/prevent it from going down, and they help shrug the shoulders.	What are the chief muscles responsible for elevating the scapula or stabilizing it under downward load and what do they do?
The latissimus dorsi, serratus anterior, and pectoralis major help in this process, and they may help prevent the scapula from rising upwards.	What are the chief muscles responsible for stabilizing the scapula under an upward load and what do they do?
The Trapezius (upper and lower fibers), and the Serratus Anterior help rotate the scapula by rising the lateral side of the scapula and dropping the medial side of the scapula, which enables us to raise our hand even higher at times.	What are the chief muscles for upward rotation of the scapula and what do they do?
The Levator Scapulae, Pectoralis Minor, and Rhomboids all help rotate the scapula by rising the medial side and lowering the lateral side.	What are the chief muscles responsible for downward rotation of the scapula and what they do?
The Pectoralis Minor and Serratus Anterior help draw the scapula closer to the ribs, thus pulling it anteriorly, which enables us to do push-ups.	What are the chief muscles responsible for protraction of the scapula and what do they do?
The Trapezius (middle and lower fibers) and Rhomboids help by bringing the scapula superiorly/medially and inferiorly/medially, thus puling the scapula medially, which helps us square our shoulders.	What are the chief muscles responsible for retraction of the scapula and what do they do?
It enters via facilitated diffusion.	How does glucose enter the cell?
It is converted to glucose-6-phosphate so that the glucose cannot leave the cell.	What is glucose converted to when glucose enters the cell?
This is when a whole bunch of glucose is converted into glycogen.	What is glycogenesis?
This is when glycogen is converted into glucose.	What is glycogenolysis?
Most can, but the nervous system can only use glucose.	Can fatty acids be used by all tissues and organs?
When glucose is not available, like before breakfast, etc.	When do most cells use fatty acids?
This is the process by which lipids are made.	What is lipogenesis?
This is when stored fat (triglycerides) are broken down into glycerol and fatty acids, which can allow the glycerol to be converted into glucose. If, however, our body has too many fatty acids it can alter our pH.	What is lipolysis?
It is produced during anaerobic glycolysis.	When is Lactic Acid produced?
It diffuses out of muscle cells where it can easily be taken up by our liver, heart, and kidney cells.	What does Lactic Acid tend to do?
Adenosine Triphosphate is the main source of energy that our body runs off of.	What is ATP?
Only a few seconds is generally "stored" in our body at any time.	How much ATP is generally stored within our body?
It is used as a storage form of intracellular energy and it accumulates in cells during periods of inactivity by using ATP to transfer energy to creatine. C + ATP => CP + ADP	What is Creatine Phosphate and where does it come from?
It gives phosphate to ADP, thus regenerating ATP. ADP + CP => ATP + C	What happens to CP during active periods?
It is Nictoniamide Adenine Dinucleotide, it is derived from niacin (vitamin B3), and each can generate 3 ATP if Oxygen is present.	What is NADH, where is it derives from, and hwo many ATP can it generate?
It is Flavin Adenine Dinucleotide, it is derived from riboflavin (vitamin B2), and each can generate 2 ATP if Oxygen is present.	What is FADH2, where is it derived from, and how many ATP can it generate?
Since we do not have to use the mitochondria it is decently useful, but only gives us about 10-15 second of intense activity.	How useful is Creatine Phosphate under Anaerobic Conditions?
This is the partial oxidation, or breakdown, of glucose, it occurs in the cytoplasm, and produces 2 pyruvic acid, 2 ATP, and 2 NADH from 2 NAD+.	How does glycolysis work in anaerobic conditions, where does it occur, and what does it produce?
It is used by muscles when oxygen levels are low, and pyruvic acid converted to lactic acid.	When is lactic acid used?
No, it can easily diffuse out of cells, and is thus completely gone within 30 minutes adter exercise ends, where it is then picked up by/used as an energy source for the liver, kidney, and heart.	Does lactic acid stay in muscle cells?
This aids in rapid ATP production during intense exercise, diffusion allows ATP production to continue, and diffusion prevents pH change inside muscle fibers.	What are the benefits of lactic acid?
This produces only 5% of the ATP that aerobic respiration produces, and lactic acid causes muscle fatigue and soreness.	What are the disadvantages of lactic acid?
2 ATP and 2 NADH, but without oxygen this cannot be used to generate ATP.	What it the total energy produced by Anaerobic Metabolism?
Hyperextension => Anatomical Position: The Anterior Deltoid and Pectoralis Major Anatomical Position => Flexed Position: Pectoralis Major.	What muscles aid in flexion of the shoulder?
From Flexed Position => Anatomical Position: Pectoralis Major, Posterior Deltoid, and Latissimus Dorsi From Anatomical Position => Hyperextended Position Deltoid and Latissimus Dorsi	What muscles aid in extension of the shoulder?
Deltoid, Rotator Cuff Muscles (4), Serratus Anterior, and Trapezius.	What muscles aid in abduction of the shoulder?
Deltoid	What muscles aids in abduction of the shoulder to 90 degrees?
The middle fibers of the deltoid aid in this, and are dependent on the upward rotation of the scapula, which the serratus anterior and trapezius aid in, and the rotator cuff muscles hold the humerus tightly against rotating glenoid fossa.	What muscles aid in abduction of the shoulder from 90 degrees to 180 degrees?
Pectoralis Major and Latissimus Dorsi.	What muscles aid in adduction of the shoulder?
Slow	Slow Oxidative Fibers have slow/fast myosin ATPase on the myosin head.
Plentiful	Slow Oxidative Fibers have plentiful/deficient blood supply.
High	Slow Oxidative Fibers have low/high levels of myoglobin, which aids in storing oxygen in the muscle.
Smaller	Slow Oxidative Fibers have smaller/larger diameters which helps determine how quickly molecules diffuse in and out of the fiber.
More	Slow Oxidative Fibers have less/more mitochondria, which aids in making ATP.
They are aerobic, but will also use fatty acids if necessary.	What do SO fibers use as their energy source?
Because they use less ATP, and their need of ATP is not very high.	Why are SO Fibers resistant to fatigue?
In muscles dealing with keeping us upright, or our postural muscles.	Where would you often find Slow Oxidative fibers?
Fast	Fast Glycolytic Fibers have slow/fast myosin ATPase on the myosin head.
Deficient	Fast Glycolytic Fibers have plentiful/deficient blood supply.
Low	Fast Glycolytic Fibers have low/high levels of myoglobin, which aids in storing oxygen in the muscle.
Larger	Fast Glycolytic Fibers have smaller/larger diameters which helps determine how quickly molecules diffuse in and out of the fiber.
Fewer	Fast Glycolytic Fibers have less/more mitochondria, which aids in making ATP.
They can very quickly become anaerobic, hence having glycogen stores.	What do Fast Glycolytic fibers use as their energy source?
Rapid, forceful contractions, thus not the strongest resistance, and they fatigue rather quickly.	What kind of contraction do Fast Glycolytic fibers tend do make?
In our fingers.	Where would you often find Fast Glycolytic fibers?
They both have a lot of myoglobin and mitochondria	How are Fast Oxidative fibers similar to Slow Oxidative fibers?
They both have a fast ATPase.	How are Fast Oxidative fibers similar to Fast Glycolytic fibers?
They are intermediate in their blood supply and glycogen, and they are wider than Slow Oxidative fibers but thinner than Fast Glycolytic fibers.	How are Fast Oxidative fibers intermediate to Slow Oxidative and Fast Glycolytic fibers?
They use oxygen, but they can be both anaerobic or aerobic.	What kind of energy source do Fast Oxidative fibers use?
They have strong, repetitive contractions, but are moderately fatigue resistant.	What kind of contractions do Fast Oxidative fibers have?
In muscles primarily focusing on walking.	Where would you normally find Fast Oxidative fibers?
Both.	Gross muscle contains slow-twitch/fast-twitch/both fibers.
Muscle use/purpose and Genetics	What two factors determine the ratio of fiber types in gross muscle?
a single	Each motor unit contains _______ muscle fiber type(s).
It is when the muscle demand for oxygen is greater than the supply. This does not mean that the body is deficient by any means of oxygen, although it may be, it simply means that the body cannot get oxygen to the muscle as quickly as it needs it.	When does an "oxygen debt" occur and what is it?
Energy reserves, both Creatine Phosphate and glycogen, are rapidly depleted. Lactic Acid, therefore, accumulates since it cannot diffuse out of the muscle quickly enough. Thus, since the body is short on Oxygen, our body respires heavily to make up the lost Oxygen. Well-trained athletes end up being more efficient in their Oxygen handling, thus they experience an Oxygen debt less often.	On the short term basis, what does an oxygen debt result in?
Our body increases the amount of capillaries and capillary branching, thus glucose and oxygen can diffuse quicker and more often to the location. Our body also makes more mitochondria to use this additional oxygen more efficiently. Finally, we have more myoglobin so that we can store this excess Oxygen in case we need it later.	On a long term basis, what does an oxygen debt result in?
We have an increased size of muscle fibers, an increased number of mitochondria - since ATP is still very necessary, an increased amount of connective tissue to reduce the damage done to our muscles, and more glycogen.	What are the long-term effects of Resistance Exercise?
Mainly, the Biceps Brachii, but the Brachialis also provides some support.	What muscle(s) aid(s) in forearm flexion when the forearm is supinated?
The Brachialis helps, and the Brachioradialis especially helps after we have started moving some. Lastly, the Pronator Teres provides some minor contributions.	What muscle(s) aid(s) in forearm flexion when the forearm is pronated?
The Triceps Brachii is the only muscle to extend the forearm, and the medial head is the main head of the Triceps Brachii to do so.	What muscle(s) aid(s) in forearm extension?
The Pronator Teres can pronate the forearm.	What muscle(s) aid(s) in forearm pronation?
The Biceps Brachii is the main supinator of the forearm, thus supination is much stronger than pronation.	What muscle(s) aid(s) in forearm supination?
The Flexor Carpi Ulnaris and the Flexor Carpi Radialis.	What muscle(s) aid(s) in wrist flexion?
Wrist extensors act as synergists with digital flexors, thus giving strength when grasping something. In other words, you can hold onto something tigher when you flex your wrist backwards a bit.	How do wrist extensors and digital flexors interact?
The Extensor Carpi Radialis Longus and the Extensor Carpi Ulnaris.	What muscle(s) aid(s) in wrist extension?
There is only minor movement due to how the bone is strucured in that area.	How much movement does our wrists have when abducting?
The Flexor Carpi Radilalis and the Extensor Carpi Radialis Longus.	What muscle(s) aid(s) in wrist abduction?
There is only minor movement due to how the bone is structured in that area.	How much movement does our wrists have when adducting?
The Flexor Carpi Ulnaris and the Extensor Carpi Ulnaris.	What muscle(s) aid(s) in adducting the wrist?