A&P: Muscular System Flashcards
List the 5 functions of the Muscular System
MMMSG
- Movement
- Maintain posture/body position
- Maintain body temp
- Support soft tissue
- Guard entrances and exits (ex: Sphincters)
Cardiac muscle is composed of ______ cells called ______ that are joined together by _______ ________
individual
cardiomyocytes
intercalated disks
What is the main function of intercalated disks in cardiac muscle?
they are gap junctions which allow electrical impulses to travel to each cariomyocyte in order to contract in sync
List 3 types of muscle
Skeletal Muscle
Cardiac Muscle
Smooth Muscle
Explain why cardiac muscle cells, unlike skeletal muscle cells, do not get fatigued
Cardiac muscle cells have more mitochondria compared to skeletal muscle cells, so they rely exclusivley on aerobic respiration to generate energy (aerobic respiration = LOTS ATP MADE)
Compare the 3 muscle types: Skeletal, Cardiac, and Smooth muscle
Include: Cell/Fiber Shape, Number of nuclei, Presence of Striations, Control)
Skeletal Muscle:
Cell/Fiber Shape
- Tubular
Number of nuclei
- Multinucleated
Presence of Striations
- Striated
Control
- Voluntary
Cardiac Muscle:
Cell/Fiber Shape
- Branches
Number of nuclei
- Uninucleated
Presence of Striations
- Striated (intercalated disks)
Control
- Involuntary
Smooth Muscle:
Cell/Fiber Shape
- Spindle-shaped
Number of nuclei
- Uninucleated
Presence of Striations
- Non-striated
Control
- Involuntary
List the skeletal muscle organization from largest to smallest. Include which structures are covered by what type of fascia.
-
Skeletal Muscle (Epimysium)
-> Muscle Fascicle (Perimysium)
-» Muscle fiber/cell (Endomysium)
-»> Myofibrils
-»» Myofilaments - arranged into Sarcomeres
-»»> Actin (thin filament)
-»»> Myosin (thick filament)
What type of fascia ties adjacent muscle fibers together?
Endomysium
At the end of each muscle, the _____ fibers of all three layers come together to form a bundle called a ______
collagen
tendon
Tendons are bands of ____ fibers that attach muscle to the _____ of bone
collagen
periosteum
What is defined at the cell membrane of a muscle fiber?
sarcolemma
What is defined at the cytoplasms of a muscle fiber?
sarcoplasma
What is the sarcoplasmic reticulum?
It is the ER of a muscle fiber that stores Calcium during relaxation (also releases Calcium into sarcoplasma when stimulated by an AP)
What is the structural and functional unit of skeletal muscle?
sarcomere
What two proteins make up the sarcomere?
actin
myosin
What do a narrow network of tubules, T-tubules, allow for?
T-tubules allow for an AP to move through the skeletal muscle cell/fiber
How does the distance between Z lines change during muscle contraction?
Distance between Z lines/disks are reduced
Does the H zone change during muscle contraction? If yes, how so?
Yes, H zone consists of 100% myosin, so when actin gets pulled towards the M line, there is more overlap between myosin and actin. Therefore, the H band will shorten.
Does the A band change during muscle contraction? If yes, how so?
No, the A band measures the entire length of mysoin. When muscle contracts, the length of the sarcomere will shorten BUT the length of the filaments (actin and myosin) do NOT change. Therefore, the A band remains the same length during muscle contraction.
Be able to draw a complete sarcomere with appropriate disks/bands. Label each disk/band
check answer in Muscular System notes
Know what each of these bands measure/fxn:
M line
H band
A band
I Band
Z disks
- M line: anchors down myosin
- H band: measures 100% myosin; NO overlap
- A band: measures entire length of myosin; varying overlap with actin
- I band: measures 100% actin; bisected by Z disks
- Z disks: bisects I band
What is the region where the end of a neuron meets a muscle fiber
neuromusclular junction
Which neurotransmitter triggers contraction?
Acetylcholine (ACh)
The permeability of ____ ions on the muscles surface at the NMJ changes when ACh is released into the synapse.
Sodium (Na+)