Muscles Flashcards
Cardiac Muscle Characteristics
Where: Heart Appearance: Striated Shape: Branching Y Action: Involuntary Nucleus: Uni-Bi Rhythmic: Rhythmic Intercalated Discs: Yes Speed of Contraction: Slow
Smooth Muscle Characteristics
Where: Visceral (Internal Organs) Appearance: Non-striated Shape: Tapered point Action: Involuntary Nucleus: Uni Rhythmic: Either due to Blood Vessels (related to heart) Intercalated Discs: No Speed of Contraction: Slower
Why do muscles have the ability to move?
- Contraction
- Irritability
- Extensibility
- Elasticity
Connective Tissue Wrappings
- Cells are surrounded and bundled by connective tissue
- Endomysium: Enclosing a single muscle fiber
- Perimysium: Wraps around a fascicle (bundle) of muscle fibers
- Epimysium: Covers the entire skeletal muscle
- Fascia: On the outside of the epimysium
Sites of Muscle Attachment
- Bones
- Cartilages
- Connective Tissue Coverings
Skeletal Muscle Functions
- Movement
- Posture (Jelly Donut)
- Heat
- Stabilize Joints
Sacrolemma
-Specialized plasma membrane
Myosin Filaments
- Thick filaments
- Composed of the protein myosin
- Has ATPase enzymes
- have heads (extensions, or cross bridges)
- Myosin and actin overlap somewhat
Actin Filaments
- Thin filaments
- Composed of a protein actin
- Anchored to the Z disc
Sarcoplasmic Reticulum
- Specialized smooth endoplasmic reticulum
- Stores and releases calcium (calcium is important for energy production)
- Surrounds the myofibril
Myofibrils
- aligned to give distinct bands
- I Band= Light band
- Contains only thin filaments (actin)
- A Band= Dark band
- Contains the entire length of the thick filaments (myosin)
- I Band= Light band
Sacromere
- Contractile unit of a muscle fiber (z line to z line)
- Organization of the sacromere
- Myofilaments
- Thick filaments= myosin filaments
- Thin filaments= actin filaments
- Myofilaments
What Skeletal Muscles need to Contract
- Strength of stimuli
- Ca+
- Na+
- Blood flow
- Glucose
- Red Blood Cells
- Oxygen (breaks down sugar)
- Iron (attracts oxygens)
- Phosphate bonds Cp+ ATP
- Number of mitochondria
- K+
Graded Responses
-different degrees of skeletal muscle shortening
How graded responses can be changed
- The frequency of muscle stimulation
- The number of muscle cells being stimulated at one time
Twitch (Graded Response)
- Single, brief contraction
- Not a normal muscle function
Tetanus (Type of Graded Response)
- Summing of contractions
- One contraction is immediately followed by another
- The muscle does not completely return to a resting state
- The effects are added
Unfused Incomplete Tetanus (Graded Response)
- Some relaxation occurs between contractions
- The results are summed
Fused Complete Tetanus (Graded Response)
- No evidence of relaxation before the following contractions
- The result is a sustained muscle contraction
Flexion
- Ordinary Body Movement
- Decreases the angle of the joint
- Brings two bones closer together
- Typical of hinge joints like knee and elbow
Extension
- Ordinary Body Movement
- Opposite of flexion
- Increases angle between two bones
Rotation
- Type of Ordinary Body Movement
- Movement of a bone around its longitudinal axis
- Common in ball and socket joint
- Example is when you move atlas around the dens of axis (shake your head “no”)
Abduction
- Ordinary body movement
- Movement of a limb away from the middle
Adduction
- Ordinary body movement
- Opposite of Abduction
- Movement of a limb toward the midline
Circumduction
- Type of ordinary movement
- Combination of flexion, extension, abduction, and adduction
- Common in ball-and-socket joints
Dorsiflexion
- Ordinary movement
- Lifting the foot so that the superior surface approaches the shin
Plantar Flexion
- Ordinary movement
- Depressing the foot (pointing the toes)
Inversion
- Special Movement
- Turn sole of foot medially
Eversion
- Special movement
- Turn sole of foot laterally
Supination
- Forearm rotates laterally so palm faces anteriorly
- “Raise the roof”
- Special movement
Pronation
- Forearm rotates medially so palm faces posteriorly
- Special movement
Opposition
- Move thumb to touch the tips of other fingers on the same hand
- Special movement
Types of Muscles
- Prime mover– muscle with the major responsibility for a certain movement
- Antagonist: Muscle that opposes or reverses a prime mover
- Synergist: Muscle that aids a prime mover in a movement and helps prevent rotation
- Fixator– Stabilizes the origin of a prime mover
Ways to Name Muscles
- By direction of muscle fibers (Ex: Rectus Abdominus
- By relative size of the muscle (Ex: Gluteus Maximus
- By location of the muscle (Ex: Temporalis)
- By the number of origins (Ex: Triceps= three heads)
- By location of the muscles origin and insertion (Sternocleidomastoid)
- By shape of the msucle (Ex: Deltoid)
- By action of the muscle ( Flexor &extensor)
Origin Vs. Insertion
- Origin= closer to the midline
- Insertion= farthest from the midline
Anaerobic
- Starts w/ enzymes
- Glycolysis (splitting of glucose) C6H12O6–> c3h6o3 (pyruvic acid) and 2 ATP
- if oxygen does not get to it, it keeps breaking down to create lactic acid
- Produces:
- 2 ATP
- Lactic Acid
- Produces:
Aerobic Respiration
- Glucose –> pyruvic acid —> Mitochondria uses Amino and fatty acids
- Produces:
- CO2
- h2o (water)
- 32 ATP (per glucose)
How much ATP is produced by each respiration cycle?
Krebs cycle= 2 ATP Anaerobic = 2 ATP Aerobic= 32 ATP ------------ 36 ATP
Synaptic Cleft
- Gap between nerve and muscle
- Nerve and muscle do not make contact
- Area between nerve and muscle is filled with interstitial fluid
Neuromuscular Junction
-Association site of axon terminal of the motor neuron and muscle
Neurotransmitter
- chemical released by nerve upon arrival of nerve impulse
- The neurotransmitter for skeletal muscle is acetylcholine(ACh)
- Acetylcholine attaches to receptors on the sarcolemma
- Sarcolemma becomes permeable to sodium (Na+)
Tendons
- Cord-like structures
- Mostly collagen fibers
- Often cross a joint due to toughness and small size
Aponeurosis
- Sheet-like structures
- Attach muscles indirectly to bones cartilages, or connective tissue coverings
Skeletal Muscle Characteristics
Where: Attached to bones Appearance: Striated Shape: Long Columnar Action: Voluntary Nucleus: Multi-nucleated Rhythmic: Non-rhythmic Intercalated Discs: No Speed of Contraction: Slow to Fast
Steps to Muscle Contraction
- An action potential in a motor neuron cause acetylcholine to release in the synaptic cleft
- Acetylcholine binds with receptors on the cell membrane on the muscle fiber, opening Ca+ (Calcium) channels
- Calcium is released from the terminal cisternae into the muscle fiber
- Calcium binds to troponin
- Troponin shifts tropomyosin, which was blocking the active site on the actin
- Myosin heads attach to actin by breaking down ATP to ADP and a phosphate via Myosin-ATPase
- The Myosin head forms a “cross bridge” on the active site of the actin filament
- The cross bridge pulls actin, which slides over the myosin— known as the Power Stroke
- The release of ADP completes the cross-bridge movement and ATP attaches to myosin, breaking the actin-myosin cross-bridge
- Every time ATP is split into ADP + P, the myosin head cocks into place to form another cross bridge with actin
-Entire process shortens the sarcomere, which is functional unit of a muscle cell
