Chapter 7: Muscular System Flashcards
Cardiac muscle
Heart- involuntary
Has 1 centrally located nuclei
Rich in mitochondria
Contract heart to propel blood through the body
Functions of muscles
- Movement
- Maintain posture
- Respiration
- Production of body heat
- Communication
- Heart beat
- Contraction of organs and vessels
Smooth muscle
Located in walls or hollow organs, blood vessels, and glands
Function: to compress organs, ducts, tubes, and so on.
Has less actin and myosin
1 centrally located nucleus
Involuntary
Skeletal muscle
Voluntary Attached to the bone Many nuclei per cell Longest type of muscle 40% of body weight
Abilities of the skeletal muscles
- Contractibility: shorten
- Excitability: respond to stimuli
- Extensibility: stretch
- Elasticity: recoil
Coverings of the skeletal muscle
Endomysium
Perimysium
Epimysium
Endomysium
Fine connective tissue sheath that surrounds each muscle fiber.
Many nuclei
Muscle fiber
Skeletal muscle cells
Perimysium
Connective tissue that surrounds each muscle fasciculus
Muscle fasciculus
Bundle of muscle fibers
Epimysium (fascia)
Connective tissue that surround entire skeletal muscle (outside)
Myofibril
Thread like proteins that make up muscle fibers
Myofilament
Proteins that make up myofibrils
Ex. Actin and myosin
Sarcoplasm
Cytoplasm of muscle fiber
Sarcolemma
Cell membrane
-contains T-tubules
T-tubules (transverse)
Wrap around sarcomeres at A band
Associated with sarcoplasmic reticulum
Sarcoplasmic reticulum
Type of smooth ER (SER)
Surrounds myosin
Stores and releases Ca2+
Motor neuron
Nerve cells that carry action potentials to muscle fibers
Neuromuscular junction
(Synapse)
Stupid hoe couldn’t just say that. Shiet.
Where nerve cell and fiber meet.
I’m gonna leave random shit places now to bug you while you study. Holla.
Presynaptic terminal
End of nerve cell.
The axon bitch.
Postsynaptic membrane
Muscle fiber membrane
Synaptic cleft
Space between presynaptic terminal and postsynaptic membrane.
Synaptic vesicle
In presynaptic terminal (nerve side)
Store and release neurotransmitters
Ex. ACh
Resting membrane potential
Charge difference across the membrane of a resting cell.
Outside cell Inside cell
Na+ K+
+ charge - charge
No channels closed. Some K+ open
The inside of the cell is negative even though K+ is positive because it is able to diffuse out the cell freely but other larger negative molecules can’t.
Action potential
“Electricity”
Causes muscles to contract
Stimulus that causes rapid depolarization and repolarization
Depolarization
Change in charges
Inside becomes more positive and outside more negative
Na+ channel is open
Repolarization
Na+ channels close
Change back to resting potential
Hyperpolarization
To increase polarization of membranes of muscle cells
Neurotransmitter
Chemical that stimulates or inhibit a muscle fiber
ACh
Acetylcholine
Motor unit
Group of muscle fibers that motor neuron stimulates
Actin
Thin myofilament
Contain myosin binding sites
Troponin
Attachment site on actin for Ca2+
Tropomyosin
Filament on grooves of actin
Attachment site on actin for myosin (head)
Myosin
Thick filament Resemble golf clubs Have 3 properties: 1. Bind to attachment sites 2. Bend and straighten during contraction 3. Break down ATP
Sarcomeres
1 contractile unit
Contains actin and myosin
Z disk
Protein fibers that form attachment site for actin
H zone
Center of sarcomere
Contains only myosin
I band
Contains only actin
A band
Where actin and myosin overlap
M line
Where myosin are anchored
Isometric contraction
The length of the muscle doesn’t change but the amount of tension increases. (Weight)
Orgin
The non movable end of the muscle
Insertion
The movable end of the muscle
Synergist
Muscles that work together to produce a movement.
Antagonist
Muscles that oppose each other
Occipitofrontalis
Move scalp and forehead
Orbicularis oculi
Close eyes
Orbicularis oris
Close lips
Zygomaticus major/minor (lips)
Elevate and abduct
Masseter
Elevate and protracted mandible
7th step of sliding filament model
Myosin heads bind to actin (cross-bridge)
8th step of sliding filament model
P is released from myosin heads and heads bend toward center of sarcomere
9th step of sliding filament model
Bending forces actin to slide over myosin (powerstroke)
10th step of sliding filament model
Acetylocholinesterase (Ach-E: enzyme breaks down ACh) is released, Na+ channels close, muscle contraction stops
All or None Law
Either muscle contacts or it doesn’t no inbetween.
Threshold
weakest stimulus needed to produce a response
Twitch
Rapid contraction and relaxation of a muscle
Tetanus
Muscle remains contracted
Isometric
Amount of tension increases (weight)
Isotonic
Amount of repetitions increases (shorten)
Tone
Constant tension over a long period of time
Orgin
non moveable end of muscle
Insertion
movable end of muscle
Belly
Middle of muscle
Synergist
muscles that work together
Antagonist
muscles that oppose each other
Skeletal muscles are named according to:
- Location
ex. tibialis anterior - Orgin/Insertion
ex. Sternocleidomastoid - Size
ex. Gluteus maximus - Shape
ex. deltoid - Function
ex. masseter
Occipitofrontalis
move scalp and forehead
Orbicularis oculi
Close eyes
Orbicularis oris
Close lips
Zygomaticus major/ minor (lips)
Elevate and abduct
Masseter
elevate and protracts mandible
External intercostals
elevate ribs for inspiration (inhale)
Internal intercostals
depress ribs during forced expiration (exhale)
Diaphragm
moves during quiet breathing
Rectus abdominis
center of abdomen
compress abdomen
External abdomen oblique
side of abdomen
compresses abdomen
Internal abdominal oblique
compresses abdomen
runs perpendicular to external abdominal oblique
Transverse abdominis
compresses abdomen
Trapezius
very superficial
shoulders and upper back
extends neck and head
Pectoralis major
Chest
flex shoulder,
Serratus anterior
Between ribs
elevates ribs
Deltoid
Shoulder
abductor of upper limbs
Rectus abdominis
Center of abdomen
Compress abdomen
External abdominal oblique
Sides of abdomen
Compress abdomen
Internal abdominal oblique
Compresses abdomen
Runs perpendicular to external abdominal oblique
Transverse abdominis
Compresses abdomen
Quadriceps femoris
4 thigh muscles. Primary extensors of the knee.
- Rectus femoris
- Vastus medialis
- Vastus lateralis- used as a muscular injector site
- Vastus intermedius
Hamstring
Posterior of thigh
Flexes knee rotates leg, extends hip
3 hamstring muscles
Biceps femoris
Semimembranosus
Semitendinosus