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Intercalated Disks
An undulating double membrane separating adjacent cells in cardiac muscle fibers. TERM 2
Coracobrachialis
DEFINITION 2 The smallest of the three muscles that attach to the coracoid process of the scapula. Adducts and flexes the arm. TERM 3
Motor Unit
DEFINITION 3 A single -motor neuron and all of the corresponding muscle fibers it innervates; all of these fibers will be of the same type. TERM 4
Perimysium
DEFINITION 4 A sheath of connective tissue that groups muscle fibers into bundles (anywhere between 10 to 100 or more) or fascicles. TERM 5
epimysium
DEFINITION 5 A layer of connective tissue, which ensheaths the entire muscle.
endomysium
A layer of connective tissue that ensheaths a muscle fiber and is composed mostly from reticular fibers. TERM 7
acetylcholine
DEFINITION 7 A neurotransmitter in both the peripheral nervous system (PNS) and central nervous system (CNS) in many organisms including humans. TERM 8
Fascia
DEFINITION 8 A fascia is a layer of fibrous tissue that permeates the human body. Separates skeletal muscles TERM 9
ATPase
DEFINITION 9 A class of enzymes that catalyze the decomposition of adenosine triphosphate into adenosine diphosphate (ADP) and a free phosphate ion. TERM 10
transverse tubules
DEFINITION 10 A deep invagination of the sarcolemma, which is the plasma membrane, only found in skeletal and cardiac muscle cells.
motor unit
recruitment
The progressive activation of a muscle by successive recruitment of contractile units to accomplish increasing gradations of contractile strength. TERM 17
Perimysium
DEFINITION 17 A sheath of connective tissue that groups muscle fibers into bundles (anywhere between 10 to 100 or more) or fascicles. TERM 18
Endomysium
DEFINITION 18 A layer of connective tissue that ensheaths a muscle fiber and is composed mostly from reticular fibers. TERM 19
Epimysium
DEFINITION 19 A layer of connective tissue, which ensheaths the entire muscle. TERM 20
Smooth muscle fibers: Visceral Smooth
Muscle
DEFINITION 20 Single-unit smooth muscle Sheets of muscle fibers Fibers held together by gap junctions Exhibit rhythmicity Exhibit peristalsis Walls of most hollow organs
Smooth muscle fibers: Multi-unit Smooth
Muscle
Less organized Function as separate units Fibers function separately Iris of eye Walls of blood vessels TERM 22
Levers
DEFINITION 22 Rigid bar bones Fulcrum point on which bar moves; joint Object - moved against resistance; weight Force supplies energy for movement; muscles TERM 23
Diff. in smooth and skeletal muscle
contraction:
DEFINITION 23 Smooth muscle lacks troponin Smooth muscle uses calmodulin Two neurotransmitters affect smooth muscle:Acetlycholine (Ach) and norepinephrine (NE) Hormones affect smooth muscle Stretching can trigger smooth muscle contraction Smooth muscle slower to contract and relax Smooth muscle more resistant to fatigue Smooth muscle can change length without changing tautness TERM 24
Similarities in smooth and skeletal muscle
contraction:
DEFINITION 24 Interaction between actin and myosin Both use calcium and ATP Both are triggered by membrane impulses TERM 25
Compared to skeletal muscle fibers, smooth
muscle fibers are:
DEFINITION 25 Shorter Single, centrally located nucleus Elongated with tapering ends Myofilaments randomly organized Lack striations Lack transverse tubules Sarcoplasmic reticula (SR) not well developed
