Flashcards in Lecture notes muscle 2 nervous Deck (37):
What are muscle proteins?
Myofilaments: thick and thin
Thick filament:myosin, a swivel headed protein chain
Thin filament:Actin, tropomyosin, troponin (proteins!): Double strand of actin plus strands of tropomyosin.
The tropomyosin in place
A Bands are
(dark) includes H zone, M
line & zone of (thin & thick filament) overlap
I Bands are
(light); the region between the A band &
Z line containing primarily thin filaments
Z line functions as
The connecting framework for
the thin filaments and defines the borders of the sarcomere (from Z line to Z line)
H zone or H band, is also lighter since it has
Thick filaments only & the M line running down
What are the events of muscle contraction?
Divided into two parts
1. Message (impulse) travels from CNS to sarcomere- conduction
2. Proteins (Actin & Myosin) move relative to each other- “sliding filament”-
Events of conduction
• Neuromuscular junction
• ACH across the synaptic gap (cleft)
• Stimulates action potential on sarcolemma
• Down T-tubules
• Ca++ release from terminal cisternae
Ca++ release begins events of?
What is the current model of muscle contraction?
The sliding filament theory
How are muscle fibers and neurons similar?
1) Both their membranes can conduct action potentials
2) They both show an all-or-nothing response.
3) They both must reach a threshold level to
trigger an action potential...
Motor units are
• One neuron and all the muscle cells it
• Allows for fine and gross muscle control
• Less cells per motor unit = fine control – Eye muscles
• Muscles of the legs = more cells per motor unit...
Fast fibers v. slow fibers
• quick to contract • Fatigue easily
• Lack myoglobin (anaerobic) • White in color
• Most fibers are Fast or White fibers
• can sustain contraction • Have myoglobin and extensive blood supply (aerobic)
• Red in color = Red fibers
• For example; Posture muscles...
Intermediate fibers are?
• Moderate endurance
• Red in color
• #s depend upon exercise!
• Fast fibers become intermediate fibers when used heavily
• Loss of muscle mass
• Lack of use
• Loss of proteins
• May result in cell loss
• Never regain those cells
• Increase in mass
• Not increase in fibers (cells)! • More myofibrils
• More mitochondria
• More blood supply
￼• More glycogen!
The nervous system is divided into two parts
The central nervous system (CNS) and ￼Peripheral nervous system (PNS)
The central nervous system (CNS) is
Brain (cerebrum, cerebellum, brainstem) & Spinal cord
The peripheral nervous system (PNS) is
Everything else that conducts nerve impulses outside of the brain & spinal cord (cranial & spinal nerves; ganglia)
Fibers, cell bodies, and myelin for CNS
*Fibers bundled as tracts
*Cell bodies in nucleus
*Myelin by oligodendrocytes
Fibers, cell bodies, and myeline for PNS
*Fibers bundled as nerves
*Cell bodies in ganglion
*Myelin by neurolemmocytes
From senses to CNS
From CNS to muscle or gland
Structural and functional unit of the nervous system
What are the anatomical types of neurons?
Cell body off to the side; sensory neurons
A single dendrite & a single axon arising from opposite poles of the cell body; more rare; special senses
The most common type in the CNS; several dendrites & a single axon that may have one or more branches; motor neurons
Sensory are what types of neurons
Motor are what type of neurons?
Interneuron (association) is
Located entirely in the CNS
Nerve impulse is
*Also called an Action Potential.
*Movement of an electrical charge along the plasma membrane of a neuron
*The result of a change in voltage on either side of the membrane
*Speed is affected by size of fiber
*Speed is affected by insulation of axons
Resting potential is
-70 mv (millivolts) because the difference between the sides of the membrane due to ion pumps and diffusion