skeletal Muscle/Muscles Flashcards
Muscles contract when
electricity is present
Muscles relax when
Electricity is absent
Muscle cells are called
Muscle fibers
The simple structure of a muscle
Muscle> Fascicle> Muscle fiber
Proteins (myofilaments) that help muscles contract
Actin (thin) and Myosin (thick)
Skeletal muscle (location)
Attached to your bones (ex. face)
Function of skeletal muscle
Movement, maintaining posture, produces heat when it contracts
Cardiac muscle description
Found in the heart, has striations, highly interconnected throughout the body,
Cardiac muscle functions
mostly involuntary, and pumps blood through arteries and veins
Smooth muscle description
Found in organs like: stomach, intestines, blood
vessels, bladder, eye, reproductive organs.
Has no striations
Smooth muscle functions
Contracts slowly (peristalsis)
push and digest food.
Contractions to prepare for childbirth
Tendon
Connects skeletal tissue to bone
muscle
Made up of fascicles
Epimysium
CT sheath that surrounds the entire
muscle
Perimysium
CT sheath that surrounds each fascicle
Fascicle
A bundle of muscle fibers
Muscle Fiber
A muscle cell, made of myofibrils
Endomysium
CT sheath that surrounds each muscle fiber
Sarcolemma
Plasma membrane around each muscle fiber
Myofibril
Long proteins that make up each muscle fiber
Sarcomere
Line up to form myofibrils
Where contraction happens
Myofilaments
Make up sarcomeres
Actin & myosin
sarcoplasmic reticulum
Regulates level of calcium in a muscle fiber
T-tubules
part of the sarcolemma that protrudes deep into the muscle fiber interior
T-tubules function
Allows for electrical impulses to reach the deepest parts of the sarcoplasmic reticulum
Receptors
binding sites on the muscle fiber
that receive neurotransmitters
Motor neurons
neurons that deliver
impulses (messages) from the brain to the
muscles; stimulates the skeletal muscle
fibers to contract
Actions potential
an electrical impulse that
travels through a motor neuron
Neuromuscular junction:
where a motor
neuron and a muscle fiber come together
Axon terminal
the end of the axon of a
neuron (sends an impulse out)
Synaptic cleft
the space between the axon
terminal of a motor neuron and a muscle
fiber
Neurotransmitter
a chemical message released by neurons
ACH
acetylcholine; the neurotransmitter
that motor neurons use to “tell” skeletal
muscle to contract!
Name all the nine steps of neuromusclar juntionv(9)
1: The brain decides to contract a skeletal muscle
2: Motor neurons carry the action potential
down the spinal cord to the skeletal muscle
3: The action potential arrives at the
neuromuscular junction
4: The action potential causes the axon terminal to release ACh
5: ACh binds to receptors on the sarcolemma
6: The binding causes the action potential to
travel down the sarcolemma
7: The action potential travels down the T
tubules
8: The sarcoplasmic reticulum is stimulated by
the action potential and releases Ca2+
9: Ca2+ triggers the muscle fiber to contract!
name the muscle anatomy
Myosin
Thick myofilament
Has “heads” to bind
to actin
Powered by ATP
Actin
Thin myofilament
Made of 2 actin myofilaments twisted together “Two strands of
pearls”
Has myosin binding-sites
Z line
Boundary between sarcomeres
M lines
“Middle line”
Holds together the myosin myofilaments
I bands
Light bands
Contains only thin (actin) filaments
H zone
Contains only thick filaments
A band
Dark band
Contains the entire length of a thick
(myosin) filament
Label the structure of a sacromere
Tropomyosin
Stiffens and stabilizes actin (actin is like a wet noodle)
Blocks myosin-binding sites when a muscle is relaxed
Troponin structure
Made of 3 subunits
* 1 subunit binds it to actin
* 1 subunit binds it to tropomyosin
* 1 subunit binds to calcium ions
Troponin
When a calcium ion binds to troponin, it pulls
tropomyosin off of the myosin-binding sites of actin
when is a cross bridge formed?
when a
myosin head binds to a myosin-binding site on actin
How is cross bridging possible?
because an action potential
triggers the sarcoplasmic reticulum to release
calcium ions.
what happens when a sarcomere is relaxed? (what is blocking what)
tropomyosin is blocking the myosin-binding sites
on actin.
Describe all steps of cross bridging (using the matching game given) Also name them outloud
Characteristics of muscle tissue (4)
Excitability
Contrarily
extensibility
Elasticity
describe Excitability
*Muscle’s ability to respond to stimuli (example, when your motor neurons deliver an impulse to your biceps brahii, it contracts)
describe Contractility
Muscles ability to shorten (example, when you flex ur elbow join your biceps brachii get shorter)
describe Extensibility
*Muscle’s ability to be stretched without
tearing (example, whne a gymnast does a split)
Elasticity
*Muscle’s ability to return to its original
shape
(after u stretch your muscles they don’t stay in that state)
Idenify major muscles (Use game)
poke-a-muscle
