Myology Flashcards
Define Myology
the study of muscles, their function, and their structure
What are the 3 muscle system functions?
- Movement
- maintain posture
- produce heat
what are the 3 muscle types?
- skeletal muscle
- smooth muscle
- cardiac muscle
number of nuclei in a skeletal muscle cell
multiple (located at the periphery)
what muscle cells are voluntary?
skeletal muscle
what muscle cells are in voluntary?
smooth muscle
cardiac muscle
what is a smooth muscle responsible for?
digestion
what are the 2 myofilament components?
actin
myosin
what are myofibrils composed of?
myofilaments
how many nuclei does a smooth muscle cell have?
1 (centrally located)
where are smooth muscle cells found?
hollow organs
wall of: blood vessels, urinary bladder, uterus, digestive
tract, respiratory tract
what are the 2 types of smooth muscle cells?
single unit / visceral smooth muscle (found in sheets)
Multiunit smooth muscle (found are individual fibers)
What do single-unit smooth muscle cells form?
walls of hollow organs
What are multiunit smooth muscle cells found as?
individual fibers
what muscle is used in piloerection?
multi-unit smooth muscle cells
(autonomic nervous system)
what cells are branched?
cardiac muscle cells
what connects the ends of cardiac muscle cells?
intercalated discs
what aids in the conduction of the nervous impulse to coordinate contraction?
intercalated discs
how many nuclei does the cardiac muscle have?
1 (central)
describe voluntary muscles
conscious ability to contract a muscle
e.g skeletal muscle
describe involuntary muscles
muscle contraction without conscious thought
e.g. smooth muscle and cardiac muscle
what are the 4 properties of muscle?
- Plasticity: the ability to increase volume without increasing pressure (prominent in smooth muscle)
- Contraction (shortening)
- Relaxation (return to normal length)
- Irritability (transmit an electrical wavelength along its length, cardiac muscle)
Flexors
Antagonist: extensors
bends limbs
decrease joint angle
Extensors
Antagonist: Flexor
bends limbs
Increase joint angle
Abductors
Antagonis: Adductors
Moves limb AWAY from the midline
Adductors
Antagonist: Abductors
Moves limb TOWARDS the midline
cutaneous muscles
used for piloerection
Levators
antagonist: depressors
produce a DORSALLY directed movement
lift
Depressors
antagonist: levators
Produce a VENTRALLY directed movement
lower
Sphincters
antagonist: dilators
decrease the size of the opening
eg. pupil, bladder
dialators
antagonist: sphincters
increase the size of the opening
Pronators
antagonist: supinators
move the paw inward
supinators
antagonist: pronators
move paw outwards
what are the 2 types of muscle attachment?
direct attachment
indirect attachment
describe direct muscle attachment
muscle attaches directly to the periosteum of the bone
describe indirect muscle attachment
muscle is first attached to a connective tissue (a tendon or aponeurosis)
which in turn is attached to the bone
origin
-the end of the skeletal muscle that is the most stable
-usually the end closer the the medial plane
insertion
-the end of the skeletal muscle that is most mobile
- usually most distal end
aponeurosis
-broad, flat, white connective tissue band that connects skeletal muscle to bone
- different from tendon because it’s flat (not round)
fascia
white connective tissue sheath that covers muscle bundles
name the muscle contractile proteins
actin and myosin
Where are actin molecules attached?
the ends of the sarcomere (z lines)
what causes muscle relaxation?
the removal of Ca
(when the nerve impulse stops, Ca is actively transported back into the SER)
define Sarcomere
- the basic contractile unit of muscle fiber.
- the length of a myofibril between 2 successive z-lines
describe skeletal muscle
- striated (light-dark alternating bands parallel to each other)
- voluntary
- cells are long (1-40 microns)
- multinucleated (found at the cell periphery)
- rounded/tapered ends
each skeletal muscle fiber is a muscle cell consisting of
many myofibrils
describe smooth muscle
- visceral
- non-striated
- involuntary (digestion)
- cells elongated with tapered ends (spindle-shaped)
- 1 central nucleus
- myofilaments are not well organized
- cells tightly packed with indistinct borders
- location: blood vessels, urinary bladder, uterus, digestive tract, respiratory tract
- can be single or multi-unit
neuro-muscular junction
where synapsis occurs
synaptic vesicles contain which neurotransmitter?
acetylcholine
synaptic cleft (5)
- is where the neurotransmitter is released
- space separating the nerve and muscle
- has transmitter attachment sites
- changes the permeability of the muscle cell, allowing sodium to enter
- creates an action potential that moves along the muscle cell membrane
muscle contraction has what principle?
all or nothing (full contraction or no contraction at all)
