Exam 3 study Guide Flashcards
Main functions of the muscular system
Movement of Bones or fluids example blood. Maintaining posture and body position. Stabilizing joints. Heat generation (especially skeletal muscle) Addition functions include protects organs, forms, valves, controls pupil size, causes “goosebumps”
Responsiveness or ability to receive and respond to stimuli; plasma membranes changes electrical state (- to +)
Excitability
Ability of muscle tissue to pull on its attachment points and shorten with force.
Contractility
Ability to return to original length when resting, recoil due to presence of elastin.
Elasticity
Striated and involuntary.
Cardiac Muscle
Non-striated and involuntary.
Smooth Muscle
Striated and Voluntary.
Skeletal Muscle
Dense irregular connective tissue surrounding entire muscle; may blend with fascia.
Epimysium
Fibrous connective tissue surrounding fascicle; contains nerves and bundles
Perimysium
thin layer of areolar connective tissue covering each muscle cell.
Endomysium
Organized bundle of muscle cells.
Fascicle
term used to describe the entire muscle
Belly
A individual muscle cell
Myocyte/muscle fiber
Muscle cell plasma membrane
Sarcolemma
Muscle cell cytoplasm, contains myoglobin, glycogen
Sarcoplasm
: Unique in-folding of the sarcolemma that allow for electrical signal transmission to opposite side of cell.
T-Tubules
Specialized smooth endoplasmic reticulum that stores, releases and retrieves calcium.
Sarcoplasmic Reticulum
Repeated units of contractile and regular proteins that enable shortening and lengthening of the myocyte.
Sarcomere
Arranged in a bundle with heads directed outward in a spiral array around the bundled tails. The central area (tail) is a bare zone with no heads. The thick/darker filament and the A band.
Myosin
Two intertwined strands fibrous actin; globular actin with a binding site. Regulatory proteins associated with this filament. The thin/lighter filament and the I band.
Actin
Each motor neuron and all the muscle fibers it innervates. Motor neuron sitmulates the myocyte by releasing a neurotransmitter.
Motor Unit
Overly contracted – thick filaments too close Z-discs and can’t slide
Compressed
Resting length produces greatest force when muscle contracts. Central nervous system maintains optimal length producing muscle tone.
Optimum
Stretcher out little over lapped of thin an thick does not allow for very many cross bridges to form.
Stretcher
Graph of muscle tension
Myogram
Involuntary contraction of the fibers that make up a muscle
Twitch
Events of excitation- contraction coupling; no muscle tension.
1.) Latent Period
Crossbridge formation; tension increases.
2.) Period of Contraction
2.) Period of Contraction
3.) Period of Relaxation
How does actin prepare?
Calcium is released from the sarcoplasmic reticulum it floods the sarcomeres. Calcium will then bind to the regulatory protein troponin this causes a shape change in the troponin protein which causes it to pull tropomyosin away from the actin. Actin’s binding site then becomes exposed.
What does myosin require to activate?
Myosin must be activated. The head of myosin contains a binding site for ATP. If ATP binds to myosin it is hydrolyzed. The energy released activates/energizes the myosin head and cocks it into position.
What is a cross bridge?
Once both actin and myosin are ready (binding site exposed on actin, head of myosin cocked) the contractile proteins can bind to form a crossbridge. Crossbridge form simultaneously in the sarcomere.
What is a cross bridge?
Binding of the myosin head to actin causes immediate movement, pivoting of the myosin head which pulls the actin protein closer to the center of the sarcomere. This is known as the power stroke it does not require additional ATP.
how does a crossbridge detach?
To remove the initial cross bridge, more ATP is required and must bind to the myosin head. This ATP binding removes myosin and reactivates it.
How long does the cycle repeat?
Cross bridge cycle repeats as the activated myosin head binds to a new actin site.
What happens in rigor mortis?
3-4 hours after death muscles begin to stiffen with weak rigidity at 12 hours postmortem. Dying cells take in calcium next cross bridge formation. No ATP generated to break cross bridges.
What is the length-tension relationship?
Amount of tension generated depends on length of muscle before it was stimulated.
Why is intensity of the stimulus important?
Stimulating the whole nerve with higher and higher voltage produces stronger contractions.
What about frequency of the stimulus?
Force exerted by the skeleton muscle is controlled by varying the frequency at which action potentials are sent to muscles fibers.
Moderate frequency (between 10-20 stimuli/sec) each twitch has time to recover but develops more tension than the one before, calcium was not completely put back into SR, heat of tissue increases myosin ATPase efficiency.
Treppe
Maximum frequently stimulation (40-50 stimuli/sec) The muscle has not time to relax at all, twitch fuses into smooth, prolonged contraction.
Tetanus
Muscle changes in length and moves load and thin filaments slide. Includes concentric- muscle shortens and does work. Eccentric – muscle generates force as it lengthens.
Isotonic contraction
Load greater than tension muscles can develop. Tension increases to muscle’s capacity, but muscle neither shortens nor lengthens. Cross bridges generate force but do not move actin filaments.
Isometric contraction
ATP is synthesized when ADP reacts with creatine phosphate to form creatine and ATP. ATP from this source provides energy for a short time.
Creatine Phosphate
Requires oxygen, produces energy for muscle contractions under resting conditions or during endurance exercise. Energy sources: glucose, lactic acid, fatty acids, amino acids. ATP produced 32-38 per glucose molecules. Duration: hours.
Aerobic Respiration
ATP synthesized provides energy for a short time at the beginning of exercise and during intense exercise. Produces ATP less efficiently but more rapidly than aerobic respiration. Lactic acid levels increase because of anaerobic respiration. Energy sources is glucose. Oxygen is not required. 2-4 ATP produces per glucose molecule. Duration: up to 3 minutes.
Anaerobic Respiration
Slow oxidative –Red in color, relatively small diameter and do not produce a large amount of tension. Contains more mitochondria, myoglobin and capillaries. Adapted for aerobic respiration and resistant to fatigue. Erector spinae muscles of back.
Uses oxygen for fuel, provides continuous energy, offers extended muscle contraction, fires slowly, has high endurance, great for marathoners.
Slow Twitch Fibers
Fast glycolytic, white in color, sarcoplasmic reticulum releases calcium quickly so contractions are quicker. Larger diameter and possess high amounts of glycogen, which is used in glycolysis to generate ATP quickly to produce high levels of tension. Extraocular muscles of eye.
Uses anaerobic metabolism for fuel, provides short bursts of speed, fires rapidly, fatigues more quickly, great for sprinters.
Fast Twitch Fiber
Possess characteristics that are intermediate between fast fibers and slow fibers. Produce ATP relatively quickly, more quickly than SO fibers, and thus can produce relatively high amounts of tension. Oxidative because they produce ATP aerobically, possess high amounts of mitochondria, and do not fatigue quickly.
Intermediate Fiber
Occurs when a muscle can no longer contract in response to signals from the nervous system. Can be caused by: the central nervous system (psychologic fatigue) or Depletion of ATP in muscles (Muscular fatigue)
Fatigue
Ability to maintain high intensity exercise for >5 minutes. Determined by maximum oxygen uptake. O2 max is proportional to body size, peaks at age 20, is larger in trained athletes and males. Nutrient availability, carbohydrate loading used by some athletes and packs glycogen into muscles cells.
Endurance
What are the main functions of the nervous system?
Sensory Input: detects external and internal stimuli
Integration: processes and responds to sensory input
Control of Muscles and Glands
Homeostasis: is maintained by regulating other systems
Center for Mental Activities
Consists of the Brain and spinal cord that are enclosed in bony coverings.
Central Nervous System (CNS)
Removes debris by phagocytosis in areas of infection, trauma or stroke.
Microglia Cells (macrophages)
Lines ventricles and choroid plexus. Filters blood to create cerebral spinal fluid
Ependymal Cells
Form myelin sheaths around multiple axons simultaneously.
Oligodendrocytes
Most abundant glials. Maintain composition of chemicals in the brain matrix and blood brain barrier. Convert glucose to lactate to feed neurons. React to damaged tissue and promote repair. Remove excess signaling molecules. Sclerosis is damaged neurons replaced by hardened mass of astrocytes.
Astrocytes
Nerve: Bundle of axons in connective tissue. Ganglion: Swelling of cell bodies ina nerve.
Peripheral Nervous System (PNS)
transmits action potentials from sensory receptors to the CNS.
Sensory Division
Carries action potentials to effectors away from the CNS in cranial or spinal nerves (two subdivisions)
Motor Division
Innervates skeletal muscle
Somatic Nervous System
Innervates cardiac muscle, smooth muscle, and glands (three sub divisions)
Innervates cardiac muscle, smooth muscle, and glands (three sub divisions)
Is most active during physical activity (fight or flight division)
Sympathetic Division
Regulates resting functions (rest and digest division)
Parasympathetic Division
Controls the digestive system.
Enteric Nervous System
cells that surround and support neurons
Glial Cells of the PNS
Maintains extracellular chemical composition
Satellite Cells
Form myelin sheaths around single axons
Schwann Cells
Excitable cells that transmit electrical signals
Neurons
Neurons
Cell Body (soma)
An aggregate of rough ER and free ribosomes
Nissel Bodies
Long fiber that arises from cell body and projects to target cells
Axon
Receive information from other cells through synapses
Dendrite
A insulating layer around a nerve fiber, increases signal speed, formed from wrappings of plasma membrane. 20% protein and 80% lipid (looks white). All myelination completed by late adolescence.
Myelin
