Muscular System Flashcards
process or the state of changing place or position of the body or a body part from one position to another
movement
three types of movement
- amoeboid movement
- ciliary and flagellar movement
- muscular movement
- involves the formation of pseurodpodia (false feet)
- result from localized contraction brought about by actin and myosin
- crawling motion
amoeboid movement
organisms with amoeboid movement
- microorganisms and cells (amoeba)
- white blood cells
- hairlike and has motile processes
- moves back and forth like oars, generating force in a direction perpendicular to its axis
cilia
where are cilia found
- ciliate protist
- trachea
- reproductive system
- whiplike; present singly or in small numbers
- moves with a whipping motion creating a force in the same direction as its axis
flagella
organisms with flagella
- unicellular eukaryotes
- sperm cell
- when muscles contract, they pull on skeletal elements, causing movement
- muscles work in pairs
muscular movement
organisms with muscular movement
all animals, except sponges
insects have strong, fast-beating flight muscles
invertebrate muscles (fibrillar muscle)
- supply force for movement
- restrain motion
- act on the viscera to affect their actiity
- heat production
vertebrate muscles
mechanism of muscular contraction
sliding filament theory
explains how muscle fibers contract
sliding filament theory
proposed the sliding filament theory
- Andrew Huxley
- Rolf Niedergerke
1954
two types of filaments
- actin
- myosin
actin
thin filaments
myosin
thick filaments
- organized contractile units
- basic unit of muscle contraction, spanning from one Z-line to another
sarcomere
regions in the sarcomere
- A-band
- I-band
- H-zone
where actin and myosin overlap
A-band
actin only
I-band
myosin only
H-zone
regulatory proteins in action potential
- tropomyosin
- troponin
blocks muscle contraction
tropomyosin
promotes muscle contraction
troponin
what happens during action potential in muscles
- influx of Ca2+
- binds with troponin molecules
- causes change to actin that exposes myosin binding sites
Steps in Sliding Filament Theory
- detachment
- hydrolysis
- cross bridge
- power stroke
- repeat
- ATP binds to myosin head
- myosin detached from actin
detachment
what happens in detachment
- ATP binds to myosin head
- myosin detached from actin
- ATP splits into ADP+Pi
- causes myosin head to change to the ready position
hydrolysis
what happens during hydrolysis
- ATP splits into ADP+Pi
- causes myosin head to change to the ready position
myosin binds to actin
cross-bridge formation
what happens during cross-bridge formation
myosin binds to actin
- lose ADP+Pi
- myosin head performs power stroke
power stroke
what happens during power stroke
- lose ADP+Pi
- myosin head performs power stroke
cycle continues as long as calcium ions are present and ATP is available, resulting in the shortening of sarcomeres and muscle contraction
repeat
Factors where the force generated during muscular contraction depends on
- no. of cross-bridges formed
- frequency of stimulation (rate coding)
- initial length of muscle fibers (length-tension relationship)
muscles contract faster when ligher loads are applied and slower under heavier loads due to increased resistance against contraction
shortening velocity
shortening velocity in ligher loads
faster
shortening velocity in heavier loads
slower
Functions of the Muscular System
- movement of the body
- maintainance of posture
- respiration
- production of body heat
- constriction of organs and vessels
- contraction of the heart
contraction of muscle is responsible for overall movement
movement of the body
keep you sitting and standing upright
postural muscles
keep you breathing
respiratory muscles
continuously pumps
heart muscles
muscles constantly maintain tone
maintainance of posture
muscles of the thorax carry out breathing movements
respiration
when muscles contract, heat is given off as by-product
production of body heat
General Properties of Muscle Tissue
- contractability
- excitability/irritability
- extensibility
- elasticity
- ability of the muscle to shorten forcefully/contract
- causes the strutures to which they are attached to move
- some forces oppose contraction that cause muscle to lengthen
contractability
contraction = ?
resting phase + shortening of muscles
capacity of muscles to respond to a stimulus
excitability/irritability
stimulus to contract is from nerves that we consciously control
skeletal muscle
- muscle fibers contract spontaneously
- also receive involuntary neural signals and hormonal signals to modulate force/rate of contraction
smooth and cardiac muscle
- muscle can be stretched beyond its normal resting length and still be able to contract
extensibility
- ability of muscle to recoil to its original resing length after it has been stretched
- recoil of muscle to go back to resting phase
elasticity
muscle fibers that are capable of contracting when stimulated by nerve impulses
muscle tissue
Two General Types of Muscles
- striated
- non-striated
What are the muscle tissues
- skeletal
- cardiac
- smooth
- fibers: striated, tubular and multi nucleated
- voluntary
- usually attached to skeleton
skeletal muscle
skeletal muscle fiber
- striated
- tubular
- multi nucleated
- fibers: non-striated, spindle-shaped, and uninucleated
- involuntary
- usually covering wall of internal organs
smooth muscle
smooth muscle fiber
- non-striated
- spindle-shaped
- uninucleated
- fibers: striated, branched and uninucleated
- involuntary
- only covering walls of the heart
cardiac muscle
cardiac muscle fiber
- striated
- irregular branched
- uninucleated