Muscular, Nervous, And Skeletal Systems Flashcards
A types of muscle
Smooth, cardiac, skeletal
Muscle generate force when they are activated. This is referred to as
Muscle contraction or muscle action
Connective tissue that surrounds the muscle
Epimysium
Bundles of muscle fibers
Fasciculus or fascicle
Connective tissue covering fascicle or fasciculus
Perimysium
Each muscle fiber is surrounded by
Endomysium
Which connective tissues help transmit forces
Epimysium Perimysium Endomysium & Tendon
A muscle fiber is a
Cell that is specialized to contract and generate force (tension)
What is a muscle fiber surrounded by?
A plasma membrane called sarcolemma
Function is sarcolemma
Encloses the muscle fiber contents
Regulated the passage of materials such as glucose
Receives and conducts stimuli in the form of electrical impulses or action potentials
Nuclei in muscle cells
Multinucleated as a result of embryonic fusion.
Contain DNA of the cell.
Largely responsible for adaptation to exercise (hypertrophy), adaptation to resistance training and aerobic endurance.
Within the sarcolemma is the cytoplasm called
Sarcoplasm
What energy sources are contained in the sarcoplasm?
ATP (the only direct source)
Phosphocreatine
Glycogen
Fat droplets
What organelles are in the sarcoplasm
Mitochondria (site of aerobic ATP production) Sarcoplasmic reticulum (stores calcium and regulates muscle action by altering intercellular concentration)
Specific function is sarcoplasmic reticulum.
Releases calcium into the sarcoplasm when an action potential passes to the interior of the cell via the transverse tubules.
Transverse tubules are
Channels that form from openings in the sarcolemma.
Myofibril
Columnar protein structures that run parallel to the length of the muscle fiber and contain myofilaments.
Myofilaments consist of
Myosin and actin that are arranged in a regular pattern.
Myosin filaments are
Thick
Formed from an aggregation of myosin molecules
Each molecule consists of a head, neck, and tail.
Are kept in position by the protein titin.
Actin filaments are
Thin
Formed from globular or g-actin proteins with binding sites for myosin heads.
G-actins form strands of filaments or F-actin
Contain two regulatory protein structures- tropomyosin and troponin.
Troponin
Binds to calcium and causes movement of tropomyosin away from the binding sites on actin.
Protein nebulin
Ensures the correct length of the actin filaments
Sarcomere
The contractile unit of muscle.
Extends from z line to z line.
Z-line
At the end of a sarcomere.
Anchors for actin filaments within and the connecting sarcomeres.
Actin’s extend inward from z lines.
A band
The width of a myosin filament
The dark striation of skeletal muscle.
H zone
The area of the A band that contains the myosin without the overlapping actin..
M line
The middle of the H zone, the dark line, that helps align the myosin filaments.
I band
The distance between ends of adjacent myosin filaments.
Lies partly in each if two sarcomeres.
Area of actin filaments in a resting sarcomere. Where there is mo overlapping myosin.
Gives muscles light striation.
Neuromuscular junction
Area of communication between the nervous and muscular systems.
Each muscle fiber has a single neuromuscular junction.
Sliding filament theory states that
The muscles change length when the filaments actin and myosin slide past each other but do not change length themselves.
Sliding filament theory
1. The action potential song the length of the neuron
Lead sto the release of the excitatory neurotransmitter acetylcholine (ACh) from within the axon terminal in the synaptic vesicles. The ACh enters the synaptic cleft between the axon terminal of the neuron and the muscle fiber.
Sliding filament theory
2. The ACh
Migrates across the synaptic cleft,
Binds with the ACh receptors on the motor end plate of the muscle fiber.
Sliding filament theory
3. Action potential along the sarcolemma
Travels to the the interior of the muscle fiber via T-tubules.
Triggers the relapse of calcium from the sarcoplasmic reticulum.
Sliding filament theory
4. the calcium migrates to
Bind with the troponin molecules along the length of the actin.
Sliding filament theory
5. Binding of calcium to troponin causes
Conformational change of the troponin. The tropomyosin, attached to the troponin, is therefore moved, exposing the myosin binding sites on actin.
Sliding filament theory
6. The myosin
At rest has been storing energy, energized released from the breakdown of ATP to ADPand inorganic phosphate (Pi).
When the binding sites are exposed, it is able to attach and pull the actin filament towards the center if enough force is generated.
Sliding filament theory
7. After pulling on the actin
The myosin head energy level is lower. It must bind to an ATP molecule to detach from the actin.
Once detached the enzyme myosin ATPase causes the splitting of the ATP molecule to ADP and Pi. The myosin head is reenergized.
Delayed onset muscle soreness (DOMS) occurs
24-48 hours and can last u to 4 days.
The ability to produce ATP aerobically is called
Oxidative capacity
Oxidative fibers have
Large amounts of mitochondria, capillaries, and myoglobin.
Myoglobin
Delivers O2 from the muscle cell membrane to the mitochondria enhancing aerobic capacity and lessening reliance on anaerobic ATP production
Muscles fibers with high myosin ATPase activity have a
Ghosh rate of shortening dye to rapid availability of energy from splitting splitting ATP
The opposite is so with low ATPase activity
Specific tension refers to
The amount of force a muscle fiber produces relative to it’s cross sectional area.
An efficient fiber isae go
Produce more work with a given expenditure of ATP.
Type 1 slow oxidative or slow twitch muscle fibers refer to
High oxidative, fatigu resistant Slow contacting and relaxing
Type 2a FOG - fast oxidative glycolitic
Large, powerful, moderate anearobic and aerobic metabolic capacity
Some fatigue resistance
Type 2x / fg - fast glycolytic are
Large powerful, high anearobic metsabolism.. Highly fatigable fg fibers .
Somatic nervous system
Activates the skeletal muscles
Autonomic nervous system
Controls involuntary functions such as: this hart & smooth muscle on blood vessels, glands.
Neuromuscular junction
The synapse bet a motor neuron and a skeletal muscle fiber
Projections from a neuron cell body
Dendrites
They receive excitatory or inhibitory signals from other neurons
Dendrites an cell bodies ate located are located in the gray horn of the spinal chord
An action potential that travels down the axon to innervate a muscle fiber cause the release of
ACh at the neuromuscular junction
Two sensory neurons that convey information from the muscles and joints are
Muscle spindles and Golgi tendons
Muscle spindle
Spindle shaped sensory organ
Thicker in the middle, tapered on the ends. A stretch receptor sensing changes on length. Contains intrafusal fibers with contractile protein (actin& myosin) on the ends. Wrapped by sensory receptors in the middle that carry a sensory discharge from muscle to CNS resulting in a motor response
Myotatic or Stretch Reflex
Slow static stretch is done to avoid stretch reflex
Plyometric exercises utilize stretch reflex for more powerful concentric action.
Activation of a muscle that was initially stretched.
Golgi tendon organ
Location
Function
Musculotendinous junction
Protects muscle and joint from injury.
Deforms with muscle action and conveys sensory information to the spinal cord. Leads to muscle relaxation and stimulation of antagonists.
Motor unit
A motor neuron and the muscle fibers it innervates. Same fiber types
Gives fibers their metabolic characteristics.
Number of fibers depend on size of muscles
Gradation of force - 2 ways
Motor unit recruitment - vary the number of motor units>muscle fibers that ae activated.
Rate coding - increasing the firing rate of motor units already activated.
Size principle of motor unit
1st - smaller type 1 motor units. Lower threshold.
2nd - type IIa
3rd - type IIx
These are larger. Higher threshold.
More units are activated with training
Parts of the long bone.
Articulation surface. Epiphysis. Epiphyseal plate. Periosteum. Medullary cavity. Diaphysis (shaft). Arterial opening. Compact/cortical bone. Cancellous/trabecular bone
Bone goes through a constant process called ——–
Two cell types involved are:
Remodelling
Osteoclasts and osteoblasts
Cancellous bone is the site of
Hematopoiesis - the synthesis of blood cells
Two important minerals that help form the body’s bones
Calcium and phosphorus
Wolfs law about bones
Bones will adapt according to stress placed on it.
Three examples that lead to increases in Boone mineral density.
Weight bearing exercises such as running
Resistance training
Eccentric loading
Tendons are formed from
Inelastic protein collagen
Ligaments are formed from
Collagen and an elastic protein called elastin
