Muscle Tissue Flashcards
6 functions of SKELETAL muscles:
Produce skeletal movement, Maintain body position, Support soft tissues, Guard openings, Maintain body temperature, Store nutrient reserves.
What is another name for muscle cells?
Muscle fibers.
Name what muscles are made up of and that are covered with the endomysium.
Fascicle.
What are muscle fibers made of?
Makes up a fascicle,
Contain mitochondria, multi-nuclei,
Myofybrils, and myosatellite cells,
Sarcoplastic reticulum, and t-tubules.
What is the sarcoplasm?
The cytoplasm of muscle fiber.
What is the sarcolemma?
The plasma membrane of muscle fiber.
What do the blood vessels in skeletal muscles do?
Supply large amounts of oxygen
Supply nutrients
Carry away wastes
What are myofibrils?
Bundles of protein filaments.
Allow muscle contraction.
Thin filaments: ACTIN
Thick filaments: MYOSIN
What are sarcomeres?
The contractile units of muscle in myofibrils.
Made up of actin and myosin and Titin
Bands and lines of Sacromeres:
A Band: where myosin filaments are found.
M line: center of A band, Midline of Sacromere.
Z line: center of I band, ‘z ends’ of Sacromere
H band: contain no thin filaments, only thick, area around M line
What are thick filaments?
Twisted myosin subunits that look like golf clubs. They contain Titin strand that recoil after stretching.
MYOSIN:
Tail: binds to other myosin molecules
Head: contain 2 protein subunits and reaches the nearest thin filament.
What is tropomyosin?
Double stranded filament.
Prevents interaction between actin and myosin.
What binds to tropomyosin?
The long, cylinder part of Troponin (A protein).
First dot binds to G actin.
Second dot binds to Calcium.
The Sarcoplasmic Reticulum regulates and stores what?
Calcium ions.
What is the sliding filament theory?
Thin filaments of Sacromere slide along thick filaments toward M line, while the width of A says the same, but the Z lines move closer together and the H band gets smaller.
What causes muscle relaxation?
Calcium ion concentrations fall and detaches from troponin.
What does the tension of a single muscle fiber depend on?
1) Fiber’s resting length at time of stimulation
2) Frequency of stimulation
3) Number of pivoting cross-bridges
3 phases of twitch:
1) latent period before contraction
2) Contraction phase: calcium ions bind
3) Relaxation phase: calcium ion levels fall
2 kinds of tetanus:
Incomplete tetanus: twitches reach maximum levels of tension, but continues to twitch maximally
Complete tetanus: muscles never begin to relax and is in continuous contraction
What is a motor unit?
A single motor neuron with all muscle fibers interacted by it.
3 types of skeletal muscle fibers:
1) Fast Fibers
2) Slow Fibers
3) Intermediate Fibers
Fast fibers:
Contract very quickly. Have large diameter. Large glycogen reserves. Few mitochondria. Have strong contractions. Fatigue quickly. (White Meat.)
Slow fibers:
Slow to contract, and slow to fatigue. Have small diameter. More mitochondria. Have high oxygen supply. Contain myoglobin. (Dark Meat).
Intermediate fibers:
Mid-sized.
Have low myoglobin.
Have mor capillaries than fast fibers, slower to fatigue.
What do muscles at rest metabolize?
Fatty acids and glucose (aerobic) and store glycogen.
During light activity, muscles:
Generate ATP through aerobic breakdown of carbohydrates, lipids or amino acids.
During peak activity, muscles:
Get energy provided by anaerobic reactions that generate lactic acid as byproduct.
3 Types of Muscle Tissue:
1) Skeletal: attached to bones, allows us to move
2) Smooth: many other places
3) Cardiac: the heart
Muscle Hypertrophy:
Muscle growth from heavy training.
Muscle Atrophy:
Lack of muscle use: decreased muscles.
Characteristics of Cardiocytes:
1) Small
2) Single nucleus
3) Aerobic (high in myoglobin, mitochondria)
4) Intercalated discs
Intercalated Discs are…
connecting points between cardiocytes.
SMOOTH MUSCLE:
Nonstriated tissue.
Has different arrangement of myosin and actin
