Muscles Flashcards
Myo-
or
Mys-
muscle
Sarco-
flesh (referring to muscle)
Cardiac muscle
Striated
Involuntary
Skeletal muscle
Striated (obvious stripes)
Voluntary
Smooth muscle
Not striated
Involuntary
3 Types of Muscle Tissue
Cardiac muscle
Skeletal muscle
Smooth muscle
Role of troponin-
importance in muscle contraction
Role of tropomyosin-
reinforces and importance in muscle contraction
Role of sarcomere-
are composed of long, fibrous proteins as filaments that slide past each other when a muscle contracts or relaxes.
Role of ATP-
bonds to myosin which causes detachment from actin
Role of ATP hydrolysis-
energy transferred to myosin head so repositioning occurs
Role of Ca+2
If low intracellular Ca2+
Myosin binding sites on actin are blocked by tropomyosin
Muscle stays relaxed
Role of Ca2+
If high intracellular Ca2+
Ca2+ binds to troponin
Troponin changes shape causing tropomyosin to move out of the way
Myosin can bind to actin
Muscle contracts
Role of T-Tubules-
protrudes deep into cell from sacrolemma conducts nerve impulse to myofibrils inlet for glucose, O2 and imp. ions
Role of SR-
sarcoplasmic reticulum, regulates intracellular Ca2+
acetylcholine-
The neurotransmitter substance released at the neuromuscular junction within the synaptic cleft
sliding filament theory-
is the process of muscle contraction involving the sliding of actin and; myosin myofilaments past each other to shorten the length of each sacromere.
acetylcholinesterase-
breaks down ACh, which allows chemically gated ion channels to close.
globular heads-
form “cross bridges” during contraction
cross bridge-
the portion of the myosin filaments that pulls the actin filaments toward the center of a sarcomere during contraction
synapse-
A junction that mediates information transfer from one neuron to the next or from a neuron to an effector cell
Connective Tissue Wrappings:
Endomysium
Fascicles
Perimysium
Epimysium
Endomysium-
surrounds the muscle fiber.
Fascicles-
several muscle fibers
Perimysium-
surrounds a fascicle
Epimysium-
surrounds the entire muscle
A band-
thick myosin filaments, portion of thin actin filaments
I band-
portion of thin actin filaments, Z line/disc (anchoring protein)
sarcomere-
distance between two Z lines smallest contractile unit, composed of myofilaments
myosin-
thick filament
actin-
thin filament
SR-
sarcoplasmic reticulum, regulates intracellular Ca2+
T-Tubules-
protrudes deep into cell from sacrolemma conducts nerve impulse to myofibrils inlet for glucose
striations-
alternating light and dark transverse bands across a myofibril
Z line-
separate one sarcomere from the next
Origin vs. Insertion
Origin: immovable/less movable bone
Insertion: movable bone
Tendon:
dense fibrous tissue
Aponeurosis:
flat fibrous tissue
Functions of Skeletal Muscle
- Produce skeletal movement
- Contractions pull tendons, move bones - Maintain posture and body position
- By tension in skeletal muscles - Support soft tissues
- Support organs, shield internal tissues - Guard entrances and exits
- Openings of digestive/urinary tracts - Maintain body temperature
- Heat released by working muscles - Store nutrient reserves
- Proteins in muscles can break down
Sliding Filament Theory
Steps
- Actin exposed due to Ca+2
- Myosin binds to Actin (crossbridge)
- Myosin pulls on Actin (powerstroke)- sliding it toward the center of the sarcomere.
- Myosin detaches from Actin due to ATP
- Reposition Myosin heads (thanks to ATP Hydrolysis)
- Remove Ca+2
The Neuromuscular Junction steps
- Electricity (A.P) travels down the Axon
- Vesicles release Acetycholine (Ach)
- Ach diffuses across Synapse
- Ach binds to Ach receptors on sarcomere
- Action potential generated and propagted
- Acetycholinesterase breaks down Ach
Role of Myoglobin-
an intracellular storage site for oxygen
7 Ways we name muscles
Location Shape Size # of origins Direction of muscle fibers Point(s) of origin and/or Insertion Action