Chapter 1 Flashcards
How mobile are fibrous joints?
Immobile
How mobile are cartilaginous joints?
Limtied
How mobile are synovial joints?
Considerably mobile
What type of cartilage is found at joint articulations?
Hyaline
What are fasciculi?
Bundles of ~150 muscle fibers, covered by perimysium
What connective tissue covers invidual muscle fibers?
Endomysium
What is a sarcolemma?
Muscle fiber membrane, contiguous with muscle fiber itself.
What is a motor unit?`
A motor neuron and all of the muscle fibers that it innervates.
What is the M Bridge?
Center of sarcomere. Where Myosin is anchored.
What are the Z lines?
Ends of sarcomere, where the actin anchors.
What is the arrangement of actin and myosin?
Each actin has 3 myosin around it, each myosin has 6 actins around it.
What is the A band?
Area with myosin, goes from M bridge to I zone
What is the H zone?
Center of the sarcomere where only myosin exists, no overlap with actin
What is the I zone?
Periphery of sarcomere where only actin is, no overlap with myosin.
Which parts of the sarcomere shrink when contraction occurs?
H and I zones.
What is the sarcoplasmic reticulum?
Series of tubules that release calcium from vessicles at Z lines to stimulate a contraction.
What are T tubules?
tubules that run perpendicular to sarcoplasmic reticulum and terminate near Z lines, carry action potentials into muscle fibers in a coordinated manner.
What happens when calcium is released into the sarcoplasm?
Calcium binds to troponin which shifts tropomyosin, allowing for myosin to form cross bridges with actin.
What determines force production by a muscle?
The number of cross bridges that are formed.
What must occur for power strokes to occur?
ATP hydrolyzes to ADP via the action of myosin ATPase, which allows the pulling action of the myosin head to occur.
Once this occurs, another ATP is needed to reset the initial globular myosin head position.
What does calcium regulate in muscle tissue?
Contraction, glycolytic and oxidative energy metabolism.
What is needed for contraction to occur?
Adequate calcium, ATP, myosin ATPase, and some initial overlap of myosin and actin.
What type of motor unit allows for precision?
Motor units with small numbers of fibers.
What is the all or nothing principle?
If a sufficient amount of acetylcholine is released from vesicles at nerve terminal in response to an action potential, action potential is propogated into the muscle.
A motor neuron being stimulated causes a contraction in all fibers.
What are the two ways of increasing the force generated by muscle contractions?
Temporal summation of action potentials, altering the number of motor units activated at a given time.
Describe Type I muscle fibers
Slow twitch. Efficient, fatigue resistant. High oxidative capacity, low anaerobic capacity and limited potential for rapid force development.
Describe Type II muscle fibers
Fast twitch. Inefficient, fatiguable. Low oxidative capacity, high aerobic capacity and high potential for rapid force development.
Contrast Type IIa and Type IIx muscle fibers
Type IIa has a higher aerobic capacity than IIx, surrounded by more capillaries.
What do muscle spindles do?
Monitor muscle length/stretch, use amount of stretch on muscle to determine appropriate force required to overcome resistance. Facilitate muscle activation.
What do golgi tendon organs do?
Monitor muscle tension. Protective. Inhibit muscle activation if tension is too great.
Which node initiates the beating of the heart?
SA node
Why is there a delay at the AV node?
Allow filling of the ventricles prior to ejection
What is the P wave?
Depolarization of the Atria
What is the QRS complex?
Depolarization of the ventricles, repolarization of the atria is masked here.
What is the T wave?
Repolarization of the ventricles
What are the two roles of hemoglobin?
Carry oxygen, act as an acid base buffer
What does carbonic anhydrase do?
Catalyzes reaction between CO2 and water to facilitate CO2 removal.
What is pleural pressure?
Pressure between membranes of lungs and chest wall, slightly negative
What is alveolar pressure?
Pressure in alveoli when glottis is open and there is no breathing occurring. Equivalent to atmospheric pressure.
How much energy goes to respiration at rest? During heavy activity?
3-5%, 8-15%
