Chapter 11 Flashcards
Muscle cells characteristics:
Excitability, responsiveness-
To chemical signals stretch and electrical changes across the plasma membrane
Muscle cells characteristics:
Conductivity-
Local electrical excitation sets off a wave of excitation that travels along the muscle fiber
Muscle cells Characteristics:
Contractility-
Shortens when stimulated
Muscle cells characteristics:
Extensibility-
Capable of being stretched between contractions
Muscle cell characteristics:
Elasticity-
Returns to its original rest Length, after being stretched
Voluntary striated muscle usually attached to bone
Skeletal muscle
Skeletal muscle;
striations-
Alternating light and dark transverse bands
results from arrangement of internal contractile proteins
Skeletal muscle;
voluntary-
Usually subject to conscious control.
The other muscle types are in voluntary.
Skeletal muscle cells also called
Muscle fibers or myofibers
What surrounds each muscle fiber (strand)?
Endomysuim
What bundles muscle fibers into fascicles (serving size)?
Perimysium
What surrounds entire muscle (bag)?
Epimysium
Carbohydrates stored to provide energy for exercise?
Glycogen
What acts as a calcium reservoir; it releases calcium through channels to activate contraction
Terminal cisterns
Stem cells that fuse to form each muscle fiber !early in development!
-each contributing one nucleus
Myoblasts
What cells play a role in regeneration of damage skeletal muscle tissue?
Satellite cells- Unspecialized myoblast remaining between the muscle fiber and endomysium
What are the three kinds of myofilaments?
Thick filaments-Several hundred myosin molecules
Thin filaments-Close to three different protein types (fibrous actin, tropomyosin, troponin)
Elastic filaments-Made of a huge springy protein called Titin
Elastic filaments prevent
Overstretching And provide recoil
Troponin, One of the three different protein types of thin filaments, is
Small, calcium-binding proteins on each tropomyosin molecule
Thick filaments info:
-Each molecule shape like a golf club, two Chains entertwine to form a shaft like tail and a double gobbler head
-Heads directed outward in a helical array around the bundle
-Heads on one half of the thick filament angle to the left while heads on the other half angle to the right
-Bare zone with no heads in the middle
Of the myofilaments, what are the contractile proteins? (They do the work of contracting)
Myosin and actin
Of the myofilaments, which act as regulatory proteins?
- They determine when a fiber can (and cannot) contract
Tropomyosin and troponin
Check later slide 17
__________ proteins are any protein that influences the regions of a DNA molecule that are transcribed by RNA polymerase during the process of transcription
Regulatory proteins
Genetic defects in dystrophin produce disabling disease called
Muscular dystrophy
Duchenne Muscular dystrophy (DMD) is caused by
A sex linked recessive trait (1 of 3,500 males)
-most common form of MD
-Diagnosed around 5 yrs old
-Rarely live past 30 years old
When we contract the ___band disappears,
The ___band shrinks,
The ___ band stays the same
H
I
A
Slide 22??
Bands????
T/F
Unless neurotoxin, Skeletal muscle cannot contract unless stimulated by a nerve
True
Slide 28????
Somatic
Motor unit
One nerve fiber and all the muscle fibers innervated by it; They behave as a functional unit and contract in unison.
Small motor unit VS large motor unit
Small motor unit provides a fine degree of control (eye and hand muscles)
-3 to 5 fibers
Vs
Large motor units provide more strength than control (Quadriceps, femoris)
-hundreds of fibers
Point where a nerve fiber meets its target cell
Synapse
When target cell is a muscle fiber, the synapse is also called a…
Neuromuscular junction (NMJ) or motor and plate
Toxins, interfering with synaptic function can paralyze muscles.
Some pesticides contain ….
Cholinesterase inhibitors
_____ Is a form of spastic paralysis caused by toxin clostridium tetani
Tetanus (lockjaw)
-Glycine in the spinal cord normally stops…
-Tetnus toxin blocks…
-Motor neurons from producing unwanted muscle contractions
-glycine release In the spinal cord, and causes overstimulation and spastic paralysis of the muscles
The state in which the muscles are limp and cannot contract (plant poisons)
Flaccid paralysis
Type of food poisoning caused by neuromuscular toxins, greeted by the bacterium clostridium ______
-Blocks release of ACH causing flaccid paralysis
Botulism
Four major phases of contraction and relaxation:
1) Excitation-
Action potentials in motor nerve fiber lead to action potentials in the muscle fiber
Four major phases of contraction and relaxation:
2)Excitation-contraction coupling
Events that link the action potentials on the sarcolemma to activation of the myofilaments; thereby preparing them to contract
Four major phases of contraction and relaxation:
3) Contraction
Step in which the muscle fiber develops tension and may shorten
Four major phases of contraction and relaxation:
4) Relaxation
When stimulation ends a muscle fiber relaxes, and returns to its resting length
Four major phases of contraction and relaxation:
How many have the act of movement?
- First is a thought of moving
Contraction is a weak if…
If overly shortened or too stretched before stimulated
Rigor mortis begins how many hours after death?
It peaks at about?
3-4 hrs
Peaks about 12 hrs
T/F
Rigor mortis is a reaction to no ATP?
True!
muscle relaxation requires ATP and ATP production is no longer produced after death
Muscle twitch-Quick cycle of contraction and relaxation when a muscle is…
Directly stimulated (like working out) with an electrode
What is threshold?
Minimum voltage that causes a muscle twitch
Even if the same Voltage is delivered different stimuli cause twitches varying in length because …
-The muscle starting length influences tension generation
-Muscles fatigue after continual use
-Warmer muscles enzymes work more quickly
-Muscle cells hydration level influence cross-bridge formation
-Increasing the frequency of stimulus delivery increases tension output
Isometric contraction
Contraction without a change in length
-Important in postural muscle function and antagonistic muscle joint stabilization
Isometric contraction
Contraction without a change in length
-Important in postural muscle function and antagonistic muscle joint stabilization
Isotonic contraction
Contraction with a change in length but no change in tension
Ex: Concentric and eccentric
Form of isotonic contraction
Concentric contraction-
Muscles shorten as it maintains tension
Ex:lifting weight
Form of isotonic contraction
Eccentric contraction-
Muscle lengthens as it maintains tension
Ex: slowly lowering weight
Main pathway of ATP synthesis
Anaerobic fermentation-
Enables cells to produce ATP in the absence of oxygen; yields little ATP and lactate, which needs to be disposed of by the liver.
Main pathways of ATP synthesis
-Aerobic respiration
Produces far more ATP: does not generate lactate; requires a continual supply of oxygen
T/F
Oxygen is briefly supplied by myoglobin but is rapidly depleted
True
Muscles meet most ATP demand by borrowing ________ and transferring them to ADP
Phosphate
Myokinase
Transfers phosphate from one ADP to another, converting the latter to ATP
Creatine Kinase
Obtains phosphate from a phosphate-storage molecule creatine phosphate (cp) and gives it to ADP
