Muscles Flashcards
Act of contraction with muscle
must be stimulated by a nerve ending,propagate an electrical current or action potential along its sarcolemma, and have a rise in intracellular calcium levels or the final trigger for contraction
- linking the electrical signal to the contraction is excitation-contraction coupling
- skeletal muscles are stimulated by motor neurons of the somatic nervous system
- axons of these neurons travel in nerves to the muscle cells
- axons of motor neurons branch profusely as they enter muscles
- each axonal branch forms a neuromuscular junction with a single muscle fiber
A band
the dark-staining zone of a sarcomere, whose center is traversed by the H band
Cell
- each fiber is a long cylindrical cell with multiple nuclei just beneath the sarcolemma
- hundreds of centimeters long
- each cell is a syncytium produced by fusion of embryonic cell
- sarcoplasm has numerous glycosides and a unique oxygen binding protein called myoglobin
- fibers contain usual organelles,myofibrils,sarcoplasmic reticulum,and t tubules
Actin
the thin actin are found at ends of sacromeres nexts to z disc
-thin filaments do not overlap thick filaments in the lighter h zone
Action of muscles
- excitability or irritability:ability to receive and respond to stimuli or responsiveness
- contractility:the ability to shorten forcibly
- extensibility:the ability to be stretched or extended
- elasticity:ability to recoil and resume
Activation of cross bridges
cross bridge forms-myosin cross bridge attatches to actin filament, working power stroke myosin head pivots and pulls actin filament toward m line
- cross bridge detaches ATP attaches to myosin hard and the cross bridge detaches
- cocking of the myosin head energy from hydrolysis Matt cocks the myosin head into the high energy
Adductor Magnus
the long, heavy triangular muscle of the medial aspect of the thigh. The adductor magnus acts to adduct the thigh. The proximal portion acts to rotate the thigh medially and flex it on the hip; the distal portion acts to extend the thigh and rotate it laterally.
Aerobic metabolism in muscles
when muscle contraction activity reaches 70 percent of maximum they start bulging muscles compress bv,oxygen delivery is impaired,pyruvic acid is converted to lactic acid
Agonist
- A contracting muscle that is resisted or counteracted by an antagonistic muscle.
Antagonist
a muscle that acts in opposition to the action of another muscle (e.g., flexor vs. extensor).
Biceps brachii
A muscle whose long head has origin from the supraglenoidal tuberosity of the scapula and whose short head has origin from the coracoid process, with insertion into the tuberosity of the radius, with nerve supply from the musculocutaneous nerve, and whose action flexes and supinates the forearm.
Biceps femoris
A muscle whose long head has origin from the tuberosity of the ischium and whose short head has origin from the lower half of the lateral lip of the linea aspera, with insertion into the head of the fibula, with nerve supply from the tibial nerve for the long head and from the peroneal nerve for the short head, and whose action flexes the knee and rotates the leg laterally.
Brachialis
a muscle of the upper arm, covering the distal half of the humerus and the anterior part of the elbow joint. It functions to flex the forearm.
Buccinator
Muscle of cheek used for blowing and sucking
Calcium and role in contractions
-in order to contract it must be stimulated by a nerve ending,propagate an electrical current or action potential along its sarcolemma, and have a rise in intracellular calcium levels or the final trigger for contraction
Cardiac muscles differences
- striated like skeletal muscle but involuntary
- contracts at a steady rate set by hearts pace maker
- neural controls allow heart rate to respond to changes in bodily needs
- cant be replaced
- all the fibers have to contract or none will
- can’t pump out more blood than what is received
Characteristics of skeletal
:skeletal muscle tissue:packaged in skeletal muscles that attach to and cover bony skeleton
- has obvious stripes called striations
- is controlled voluntary
- contracts rapidly but tires easily
- is responsible for overall body motility
- is extremely adaptable and can exert forces ranging from a fraction of an ounce to over 70 pounds
Muscle movement
- excitability or irritability:ability to receive and respond to stimuli or responsiveness
- contractility:the ability to shorten forcibly
- extensibility:the ability to be stretched or extended
- elasticity:ability to recoil and resume
Characteristics of muscle tissue
:three types of muscle tissue,skeletal,cardiac,and smooth
- these tissues differ in structure,location,functions,and means of activation
- similarities:
Circular muscles
Occur in both smooth and skeletal,for smooth they form sphincters in stomach
Contractile units of skeletal muscles
-sacromeres:smallest contractile unit of a muscle,10000 in each of myofibrils,highly active units of actin and myosin
Contractility
contractility:the ability to shorten forcibly
Control of strong muscle
Hi
Contractions
- muscle contraction depends on two kinds of myofilaments which are actin and myosin
- muscle terms:sacrolemma(muscle plasma membrane)
Convergent muscles
Tending toward a common point.
Diaphragm
- the musculomembranous partition separating the abdominal and thoracic cavities and serving as a major muscle aiding inhalation.
Divergent muscles
Moving in different directions; radiating.
Endomysium
fine sheath of connective tissue composed of reticular fibers surrounding each muscle fiber,muscle growth
Epimysium
an over coat of dense regular connective tissue that surrounds the entire muscle,makes it a whole muscle
Excitability
or irritability:ability to receive and respond to stimuli or responsiveness
Extensibility
extensibility:the ability to be stretched or extended
Extensor capri radialis
Brevis-the bursa between the tendon of the extensor carpi radialis brevis and the base of the third metacarpal.
Longus-radial side of forearm that abducts hand
External abdominal oblique
A muscle with origin from the fifth to twelfth ribs, with insertion into the anterior lateral lip of the iliac crest, the inguinal ligament, and the anterior layer of the sheath of the rectus muscle of the abdomen, with nerve supply from the ventral branches of the lower thoracic nerves, and whose action diminishes the capacity of the abdomen and draws the chest down.
External intercostals
Muscle on ribs for breathing
Factor that controls levers
Origin?
Fascia
a sheet or band of fibrous tissue such as lies deep to the skin or invests muscles and various body organs.fascial
Fascicles
- a small bundle or cluster, especially of nerve, tendon, or muscle fibers.
Fatigue period
-intense exercise produces rapid muscle fatigue with rapid recovery,sodium potassium pump can’t restore iconic balances quick enough,low intensity has gradual fatigue,sr damaged and calcium regulation is disrupted
Fatigued muscles
muscle is in a state of physiological inability to contract
Fibrin
an insoluble protein that is essential to clotting of blood, formed from fibrinogen by action of thrombin.
Fixator
A device that provides rigid immobilization of a fractured bone by means of rods attached to pins that are placed in or through the bone.
Fulcrum
- The point or support on which a lever pivots.
Functional unit of skeletal muscles
sacromeres:Myofibril:myofilaments
Gluteus Maximus
Biggest,strongest