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