Anatomy Ch. 6
Tendon
a flexible but inelastic cord of strong fibrous collagen tissue attaching a muscle to a bone. - the hamstring of a quadruped.
Assisting muscles are called ______________
Synergists
Cordlike part that attaches a muscl to a bone
Tendon
Actin
- a protein that forms (together with myosin) the contractile filaments of muscle cells, and is also involved in motion in other types of cells - thin myofilament
Sarcomere
- a structural unit of a myofibril in striated muscle, consisting of a dark band and the nearer half of each adjacent pale band - cytoskeletal filaments: sarcomere (basic nits of contraction for muscle segments) - segment of myofbril from Z-line to Z-line
Fatigue
- ability to contract is lost * caused by prolonged use (no ATP), lack of blood (no O2), or lack of acetylcholine - result -> lactic acid build-up (cramping)
Z-line
- borders that separate and link sarcomeres within a skeletal muscle - A dark thin protein band to which actin filaments are attached in a striated muscle fiber, marking the boundaries between adjacent sarcomeres
Summation
- combination of several twitches - greater force (no relaxation pd) - leads to recruitment
Neuomusc. junction
- connects the nervous system to the muscular system via synapses between efferent nerve fibers and muscle fibers, also known as muscle cells
Anaerobic respiration
- glucose -> pyruvic acid -> lactic acid (diffuses to liver) - ATP needed (in liver) to synthesize glucose (ATP prod) - O2 debt builds: Amount required in liver cells PLUS Amt reqired to restoe ATP and creatine levels in muscles
Motor neurons
- highly branched control several myocytes
Myofibril
- highly organized bundles of myofilaments - made of myofilaments
Myocyte
- made of myofibrils - controlled by axon (from motor neuron) - close to capillaries (need oxygen) - high metabolic rate - always pull, never push - in a fascicle/muscle DON'T always contract at the same time - more myocyte, more force
Intercalated discs
- microscopic identifying features of cardiac muscle - Cardiac muscle consists of individual heart muscle cells (cardiomyocytes) connected by intercalated discs to work as a single functional organ or syncytium.
Threshold stimulus
- minimum strength required to contract -stimulates muscle
Creatine phosphate
- phosphorylated creatine molecule that serves as a rapidly mobilizable reserve of high-energy
Sarcoplasmic reticulum
- regulates the calcium ion concentration in the cytoplasm of striated muscle cells - same as ER-transport
Tetanic contraction
- sustained contraction - greater force (no relaxation pd) - more motor units respond
Myofilament
- the filaments of myofibrils constructed from proteins - types of muscle are striated muscle, obliquely striated muscle and smooth muscle - various arrangements of myofilaments create different muscles - striated muscle has transverse bands of filaments
Sacolemma
- the fine transparent tubular sheath that envelops the fibers of skeletal muscles - membrane that carries nerve impulses -- increase surface area
Latent period
- time b/w stimulus + muscle response
Fascia
a thin sheath of fibrous tissue enclosing a muscle or other organ. (Muscle covering -blends w/ epimysium
ATP
adenosine triphosphate - the molecule that cells use for energy to power all their processes
The forearm is flexed at the elbow when the __________ muscle contracts
biceps brachii
Fascicle
myocytes grouped together into bundles
The ________ of a muscle is usually attached to a fixed part
origin
A muscle responsible for most of a movement is called a ____________
prime mover (agonist)
Recruitment
the incorporation into a tissue or region of cells from elsewhere in the body
Peristalsis
the involuntary constriction and relaxation of the muscles of the intestine or another canal, creating wavelike movements that push the contents of the canal forward
Perimysium
the sheath of connective tissue surrounding a bundle of muscle fibers
The name biceps means _________________
tricepts brachii (2 heads)
Pronation
turning palm downward
Supination
turning palm upward
Rotation
Moving part around axis
Abduction
Moving part away from midline
Adduction
Moving part toward midline
Protein found within thick myofibril
Myosin
Layer of connective tissue that separates a muscle into small bundles called fascicles
Perimysium
Antagonists are muscles that resist the actions of __________ and cause movement in the opposite direction
Prime movers (agonist)
Cell membrane of a muscle fiber
Sarcolemma
Unit of alternating light and dark striations between Zline
Sarcomere
Cytoplasm of a muscle fiber
Sarcoplasm
Cellular organelle in muscle fiber corresponding to the endoplasmic reticulum
Sarcoplasmic reticulum
Myocyte
Skeletal - very long unbranched Cardiac - shorter branched Smooth - short unbranched spindle-shaped
Contraction steps/process
(1) Acetylcholine (chemical) released (2) Ca^2+ (ions) expose binding sites (actin) (3) Cross-bridges (myosin) attach to actin (4) Myosin pulls on actin (shorter sarcomere
All-or-None
(of a response) having a strength independent of the strength of the stimulus that caused it
Myoglobin
(reddish-brown) stores O2 to muscle cells
Hemoglobin
- (red) carries O2 to body cells
Twitch
- 1 short, quick contraction - high frequency w/ relaxtion pd - low force
Motor unit
- A motor unit is made up of a motor neuron and the skeletal muscle fibers innervated by that motor neuron's axonal terminals - Groups of motor units often work together to coordinate the contractions of a single muscle - all of the motor units within a muscle are considered a motor pool
Cardiac muscle function (network -> all-or-none)
- Exists only in your heart - contracts to squeeze blood out of your heart, and relaxes to fill your heart with blood
Smooth muscle location and function
- Found in the walls of hollow organs - push food through your body, expel urine from your body, help to push babies out of the body during childbirth
Aerobic respiration
- O2 used for ATP production (muscle contraction) - energy molecule -hemoglobin -myoglobin
Voluntary/involuntary
- Skeletal muscle = striated, voluntary, shaped like long fibers - Smooth muscle = nonstriated, involuntary, shaped like almonds (tapered ends), one nucleus per cell - Cardiac muscle = striated, involuntary, branched, shaped like fibers cross-linked to one another, typically one nucleus per cell
Striated tissue
- Striated muscle tissue is muscle tissue that has repeating sarcomeres, in contrast with smooth muscle tissue. - Specifically, striated muscles are: Skeletal striated muscle + Cardiac striated muscle
Motor end plate
- The neuromuscular junction connects the nervous system to the muscular system via synapses between efferent nerve fibers and muscle fibers, also known as muscle cells
Neurotransmitter
- a chemical substance that is released at the end of a nerve fiber by the arrival of a nerve impulse and, by diffusing across the synapse or junction, causes the transfer of the impulse to another nerve fiber, a muscle fiber, or some other structure
Acetylcholine
- a compound that occurs throughout the nervous system, in which it functions as a neurotransmitter.
Myosin
- a fibrous protein that forms (together with actin) the contractile filaments of muscle cells and is also involved in motion in other types of cells - thick myofilament - pulls on actin (shortens sarcomere)
Flexion
Decreasing the angle between parts
Layer of connective tissue that surrounds an individual muscle fiber
Endomysium
Layer of connective tissue that surrounds a skeletal muscle
Epimysium
Network of connective tissue that extends throughout the muscular system
Fascia
A small bundle of muscle fibers
Fascicle
Extension
Increasing the angle between parts
Membranous channel extendng inward from muscle fiber membrane
Transverse tubule
Endomysium
each myocyte surrounded by, and firmly attached to, layer of loose connective tissue -meaning within the muscle -it also contains capillaries and nerves
Epimysium
entire muscle surrounded by, and firmly attached to, layer of dense irregular connective tissue
The __________ of muscle is usually attached to a movable part
insertion