Muscular System Flashcards
Cardiac Muscle
Located in the heart
Under involuntary control
Muscle is striated - consists of light & dark bands
Smooth muscle
Found throughout the body
Under involuntary control
Muscle is non-striated - not banded
Skeletal muscle
Found attached to the skeletal system by tendons
Under voluntary control - conscious thought required
Muscle is striated but not banded
Number of functions but recognised as the facilitator of movement at joints
Characteristics - Excitability
Muscles ability to perceive and respond to electrical stimuli
Characteristics - Contractability
Ability for muscle to shorten as a result of stimulus, usually becoming shorter and thicker
Characteristics - Extensibility
Muscle is able to stretch beyond its normal length
Characteristics - Elasticity
Muscle is able to return to its normal length after stretching
Function - Movement
-Of the skeletal system at the cartilaginous and synovial joints is achieved by voluntary contraction of skeletal muscles
-Causes shortening of the muscle tissue, pulling on the tendons attached to the bones
Function - Posture
-Maintains body posture against gravity by continually adjusting due to information transmitted by nerve endings on joint capsule and muscle tension
-Tendons of many muscles extend over joints and in this way contribute to joint stability
Function - Thermoregulation
-Maintenance or improvement of body heat is assisted by skeletal muscles
-Involuntary muscle contractions (shivering) generate heat
-Metabolism is such a large mass - produces heat essential for maintenance of body temp
Function - Venous Return
-Contracting muscles act as a muscular pump by compressing peripheral veins during normal activity to help blood flow
Function - Energy storage
-Muscles are able to store glucose as glycogen within their cells
Function - Assisting breathing
Diaphragm muscle regulates breathing by changing intra-thoracic volume and pressure
Connective tissue
Binds stuff together
Muscle tissue
Enables it to contract
Nerve tissue
Carry a stimulus
Blood/vascular tissue
Carry oxygen & nutrients and remove waste products (lactic Acid)
Connective tissue - Deep facia
Binds the components together; fills in spaces between muscles while allowing free movement
Epimysium
Sheath that surrounds the whole muscle
Perimysium
Surrounds bundles of muscle fibres (fascicles)
Endomysium
Surrounds individual muscle fibres
Tendon Sheath
Synovial covering of the tendon
Tendon or aponeurosis
Formed by the epimysium, perimysium & endomysium extending beyond the fleshy part of the muscle, the belly, forming a thick rope-like tendon or a broad, flat sheath like aponeurosis
Myofibrils
Very find contractile fibres, arranged in bundles along the length of the muscle
Sarcomere
Contractile unit of striated (skeletal) muscle
Myofilaments
Microscopic threads of protein myofibrils
T-tubles
A deep channel running along the length of the sarcolemma through a striated muscle
Sarcoplasmic reticulum
Regulates calcium levels in muscle cells
Actin
This protein filament that slides across myosin
Sarcoplasm
Cytoplasm of a muscle cell
Tropomyosin & troponin
Regulatory proteins found on the actin filament and extend from the anchor points on the z-lines
Muscle fibre
Single cylindrical muscle cell made up of hundreds, or even thousands of muscle fibres bundled together and wrapped in a connective tissue covering
Concentric Contraction
-Muscle shortens and develops tension
-The angle of the joint decreases as the origin and insertion points move closer together
-EG. bicep muscle as the arm bends
Eccentric Contraction
-Muscle lengthens as it develops tension
-Angle at the joint increases as the origin & insertion points move further away
-EG. Bicep muscle when the weight is lowered back down
Isometric contraction
-Muscle remains the same length
-Angle at the joint remains unchanged as the origin and insertion points remain the same distance apart
-EG. Holding a heavy object in front of you
Muscle Info - Sternocleidomastoid
Origin - Sternum & clavicle
Insertion - Mastoid process
Action - Lateral flexion or rotation of the neck
Sliding Filament Theory - Stage 1
Electrical stimulus to a muscle is transmitted to the inside of the fibre causing
Calcium ions to be released.
Sliding Filament Theory - Stage 2
The Calcium ions bind with the Troponin molecules on the Actin filament.
Sliding Filament Theory - Stage 3
This causes Troponin to change shape and pull on the Tropomyosin opening
a gap on the Actin filament.
Sliding Filament Theory - Stage 4
The heads of the Myosin molecules can now fit into these exposed sites on
the Actin filament.
Sliding Filament Theory - Stage 5
This coupling of the Actin and Myosin causes ATP to split supplying energy to
rotate the Myosin head and pull the attached Actin fibre along with it.
Sliding Filament Theory - Stage 6
A fresh supply of ATP reaches the Myosin head allowing the Myosin to detach
itself and continue to form further cross bridges.
Sliding Filament Theory - Stage 7
The process of contraction will continue as long as a high concentration of
Calcium ions is available
Sliding Filament Theory - Stage 8
If the electrical impulses to the muscle fibre cease, the concentration of
Calcium ions drops and Tropomyosin re-covers the site on the Actin filament
Sliding Filament Theory - Stage 9
The Myosin cannot continue to form cross bridges and the process of muscle
contraction stops.
Slow twitch muscle fibres - type 1
-Aerobic
-Large amounts of myoglobin (oxygen), many mitochondria & capillaries
-Slower firing muscle fibres, work continuously & take longer to fatigue
-Long distance/duration activity
Fast twitch muscle fibres - Type 2a
-Aerobic & anaerobic
-Large amounts of myoglobin (oxygen), many mitochondria & capillaries
-Combination of type 1 & 2, slower to fatigue but not as slow as slow twitch fibres
-Middle distance/duration activity
Fast twitch muscle fibres - Type 2b
-Anaerobic
-Low amounts of myoglobin (oxygen), few mitochondria & capillaries
-Produce rapid, powerful bursts of speed the highest rate of muscular contraction & fastest to fatigue
-Short distance/duration activity
muscle hypertrophy
Strength causes an increase in volume of myofibrils increasing muscle bulk
muscle hypertrophy
Strength causes an increase in volume of myofibrils increasing muscle bulk
muscular endurance
increased training volume causes recruitment of morre slow twitch muscle fibres allowing for sustained effort during exercise
improved capillarisation
greater flow of blood to muscles due to increased aerobic activity levels
increased tendon strength
force exerted during exercise cases thickening of connective tissue & prevents injury
improver energy storage
increased activity will increase the storage & replenishment of glycogen & number of mitochondria
Reduced lactic acid production
Tolerance levels to waste product increases, increased anaerobic threshold
