Contractions
What are the two types of Contractions?
Isometric Contraction
Isotonic Contraction
What is the Endomysium?
inner layer of fine, areolar connective tissue surrounding each mm fiber, joins fibers together
What is the physiology?
Support each cell and reinforce mm
Keep contracting mm from “bursting”
All 3 sheaths continues with fibrous structures that attach mm to bone or other structures
What is the sarcolemma?
Cell membrane
Has a transmembrane potential (+outside/- inside)
What does a Triad do?
Triad allows electrical impulse traveling along T tubule to stimulate membranes of adjacent Terminal Cisternae
What is a Isotonic Contraction?
“equal tension”
Muscle tension overcomes the load, and muscle shortening occurs
Once sufficient tension has developed to move the load, the tension remains relatively constant through rest of contraction
What is the Perimysium?
central layer of tougher connective tissue that surrounds a mm fascicle
What are the 2 types of attachments with descriptions?
Direct (fleshy) attachments: epimysium of mm directly fused to periosteum or perichondrium
What are T-Tubules?
protrusions of sarcolemma which extend from membrane into sarcoplasm
conduct nerve-initiated electrical impulses to deepest regions of mm cell
What makes a Triad?
composed by two Terminal Cisternae surround a T tubule
What is a Isometric Contraction?
“equal length”
Muscle tension develops but load is not moved
What is a Fascicle?
a bundle of mm fibers with associated blood vessels and nerves
What is a Tendon?
extends as a strong, tough cord which merges with periosteum or perichondrium (conserves space at joints)
What is the sarcoplasm?
Cytoplasm.
has usual organelles with some modifications
Contains large # of glycosomes (granules of stored glycogen)
Contains large amt of myoglobin (red pigment that stores O2-similar to hemoglobin)
Contains large # of mitochondria
What is the function of a Triad?
regulates intracellular levels of Ca++ ions. Stores Ca++ and releases it on demand when mm fiber is stimulated to contract
What are the measurements of both contractions?
Isometric Contraction: measured in increasing muscle tension
Isotonic Contraction: measured in change in muscle length
What is the Epimysium?
outer layer of dense, irregular connective tissue that surrounds the entire mm, may blend with fascia
What is Aponeurosis?
extends as a broad, flat sheet which merges with fibrous coverings of other mm
What is a Sarcoplasmic reticulum?
a system of smooth endoplasmic reticulum
interconnected membranous tubules surrounding myofibrils (like a crocheted sleeve)
Most of tubules run longitudinally,
How are Isotonic contractions Classified?
Concentric = shortening of muscle
Eccentric = lengthening of muscle
Eccentric contractions are 50% more forceful than concentric
What are the Fascia?
Deep fascia: fibrous connective tissue lying between neighboring mm
Superficial fascia: fibrous connective tissue just deep to skin
What are the forms of indirect attachments?
Tendons and Aponeurosis
What is Terminal Cisternae?
End perpendicular tubule in pairs, part of Sarcoplasmic reticulum