Module 8: Muscular System Flashcards
Functions of Muscle Tissue (CHSGM)
- Control of openings & passages
- Heat Production
- Stability
- Glycemic Control
- Movement
Describe Muscle Fxn: Movement
muscle works as pulleys on bones, move internal contents and fxn in communication
Describe Muscle Fxn: Stability
help maintain body position & posture
Describe Muscle Fxn: Control of Body openings and passages
help keep internal materials moving properly; ex/ muscles in mouth, iris of eye, sphincters of digestive system
Describe Muscle Fxn: Heat Production
muscles use ATP & produce heat to maintain body temp & facilitate enzyme activity
Describe Muscle Fxn: Glycemic Control
muscles store & release sugar to help maintain homeostasis with blood levels
Universal Characteristics of Muscle cells
- Excitability
- Extensibility
- Elasticity
- Conductivity
- Contractility
Define Excitability
potential to respond to electrical or chemical stimulus and stretching
Define Conductivity
ability to carry electrical signals after local stimulus
Define Contractility
ability to shorten after being stimulated
Define Extsenibility
ability to be stretched longer between contractions without rupturing
Define Elasticity
ability to return to original shape after being stretched
How is shape of a muscle determined?
by orientation of muscle cells
How is muscle strength determined?
by muscle size, shape, and by direction the cells contract
List the 5 common skeletal muscle shapes
- Fusiform
- Parallel
- Pennate
- Circular
- Triangular
Describe muscle shape: Fusiform
wide in middle & tapered end
Describe muscle shape: Parallel
uniform in width & parallel cells, elongated straps; can span long distances, shorten & produce less force due to fewer cells
Describe muscle shape: Triangular
fan-shaped; relatively strong due to large number of cells
Describe muscle shape: Pennate
feather shaped; generate most force due to arrangement of muscle cells
Describe muscle shape: Circular
round; control movement through opening & passageways
Define muscle compartments
groups of functionally related muscles enclosed in connective tissue
True or False:
Muscle & Muscle compartments attach to tendons. The gap between the muscle & bone is spanned by ligaments
False - Muscle & Muscle compartments attach to BONE. The gap between the muscle & bone is spanned by TENDONS
Define Origin
when a muscle contracts, one end is stationary or anchored
Define Insertion
end of the muscle that attaches to mobile bone
Name the origin and insertion for biceps brachii and describe action when muscle contracts
Origin - on scapula
Insertion - on radius
- When muscle contracts, acts on radius & causes flexion of elbow
Muscles do not work on bones in isolation, List the 4 primary roles
- Prime mover
- Synergist
- Fixator
- Antagonist
Describe fxn: Prime Mover
produces primary force for action
Describe fxn: Synergist
aids primary mover
Describe fxn: Fixator
stabilizes part of body that the moving muscle is attached to
Describe fxn: Antagonist
” checks & balances”
- counteracts / opposes primary mover
- stabilizes joint
- causing more controlled action due to less excess movement & speed
A muscle is an organ, name the different layers of a muscle from superficial to deep
- Fascia
- Epimysium
- Perimysium
- Endomysium
Describe Fascia
CT that separates a muscle from other muscles, organs, or tissues.
Describe Epimysium
CT that surrounds each muscle (epi- meaning upper, outer, the surface)
Describe Perimysium
within muscle, CT that surrounds and defines fascicles (peri- meaning around)
Describe Fascicle
bundles of muscle fibers
Describe Endomysium
within fascicles, CT surrounds individual muscle fibers (endo- meaning inside)
Sarcolemma
cell membrane of muscle cell; function in excitation
Name the foldings from the sarcolemma that penetrate from one side of the cell to the other & function in conduction of impulses
Transverse (T) Tubules
Sarcoplasm
cytoplasm of muscle cells
Glycogen
- polysaccharide composed of glucose
- abundant in muscle cells
- located in sarcoplasm
- produce ATP
Myoglobin
protein that binds to & stores Oxygen; when needed oxygen can be used to help produce ATP
Sarcoplasmic Reticulum
- The Smooth ER of muscle cells
- forms sacs called terminal cisternae which store & release Ca ions essential for contraction
Myofibrils
- Most prominent organelle in Sarcoplasm
- long tube-like protein bundles
- contain Myofilaments (three types)
Myofilaments: Structure, function, 3 types
- long chains of parallel proteins
- responsible for contraction
- Thick, Thin & Elastic
Thick Filaments
- composed of Myosin
- held in place by elastic filaments that are anchored to Z-discs
- found in center of sarcomere
Myosin
- within thick filaments
- bundles of contractile protein
- has a head & tail portion
Function of the head portion on a Myosin protein
Extend from thick filament & use ATP to attach and pull on thin filaments
Thin Filaments
- composed of Actin, troponin, tropomyosin
- anchored to proteins in Z-disc & extend toward center of sarcomere
Actin
- two intertwined contractile proteins
- each having a binding site for myosin heads
Tropomyosin
- regulatory protein
- cover myosin binding sites on actin when the muscle is resting
Troponin
- positioned along tropomyosin working together to allow or prevent contractions.
- composed of binding site for Calcium
What happens when Calcium binds to Troponin?
Tropomyosin shifts positions, exposing the myosin binding sites on actin
Myosin & Actin cannot interact without _____.
Calcium
Elastic Filaments
- contain Titin
- anchor to Z-discs
- keeps Thick Filaments in place, preventing overstretching
- recoil after contractions, keeps proteins in original positions within myofibril.
Each myofibril is divided by Z-discs into smaller units called _______.
Sarcomere
Sarcomere
- collection of thick, thin and elastic filaments
- found between two adjacent Z-discs
Each Sarcomere contains two Z-discs, how many sets of Thin Filaments are there?
2 Sets of Thin Filaments
In order for muscle fibers to contract they must be ______ by nervous system cells called _____ _____.
Stimulated; Motor Neuron
Motor Neurons
cells that carry information from brain or spinal cord to muscle fibers
Motor Unit
comprised of a motor neuron & all muscle cells that receive info from its branches
Motor units are either entirely active or completely resting aka _______.
All or Nothing principle
All Neurons communicate with other cells at regions called …
Synapses
Neurons release chemical messengers called
Neurotransmitters
Motor Neurons of Motor unit communicate with muscle cells at specific synapses called
Neuromuscular Junction
Name the steps in order when a Motor Unit becomes active
Excitation
Excitation-contraction coupling
Contraction
Relaxation
Two most important factors that influence availability of ATP
oxygen & glucose levels
Glycolysis
producing ATP starting with glucose
