Physiology: V - VIII Flashcards
Hierarchy of Muscular Organization
- Muscle
- Fascicles
- Muscle Fibers/Cells
- Myofibrils
- Filaments (Action & Myosin)
Sheetlike CT that attaches muscle to muscle or muscle to bone
Aponeurosis
Sarcolemmma
Muscle Fiber Cell Membrane
Nucleation and Mitochondriation of Muscle Fibers
- Multinucleated
- Abundant Mitochondria
Intracellular system of closed saclike membranes involved in the storage of intracellular calcium in striated (skeletal) muscle cells.
Sarcoplasmic Reticulum
Sheath surrounding skeletal muscle
Epimysium
Sheath surrounding fascicles
Perimysium
Sheath surrounding muscle fibers
Endomysium
Membranous channels that run across muscle fibers
Transverse Tubules
The Thin Myofilament
Actin
The Thick Myofilament
Myosin
Segments of myofibrils between Z lines
Sarcomeres
How muscle fibers contract
sliding movements of actin and myosin that shorten the muscle fibers
Site where motor nerve and muscle fiber meet
Neuromuscular Junction
A motor neuron and the muscle fibers it controls
Motor Unit
The neurotransmitter that motor neurons use to control skeletal muscle
Acetylcholine
Where acetylcholine of a motor neuron binds
sarcolemma
What acetylcholine stimulates in a muscle fiber
Release of calcium ions from sarcoplasmic reticulum
What calcium ions from the sarcoplasmic reticulum bind to
Troponin (actin)
What that binding of calcium ions to troponin causes
Changes shape/position of troponin-tropomyosin complex, resulting in linkages forming between actin (tropomyosin) and myosin (cross-bridges)
Theory attempting to explain skeletal muscle and contraction
Sliding Filament Theory
How skeletal muscle relaxes
- Acetylcholine in synaptic cleft is decomposed by acetylcholinesterase
- Calcium ions move back into sarcoplasmic reticulum via active transport (calcium pump)
Cellular Respiration
- not dependent on O2
- breaks down glucose into lactic acid and a few molecules of ATP
Anaerobic
Cellular Respiration
- requires O2
- breaks down glucose into many molecules of ATP
Aerobic
Hemoglobin that stores O2 in muscle tissue
Myoglobin
The amount of O2 required to convert lactic acid back to glucose in the liver
Oxygen Debt
Minimal stimulus needed to produce a muscle contraction (twitch)
Threshold Stimulus
(contraction is all or none)
Contraction Speed
- Red Fiber
- Resistant to Fatigue
- Good Blood Supply
- Aerobic Respiration
- Postural Muscles
Slow Twitch
Contraction Speed
- White Fiber
- Higher Rate of Fatigue
- Poorer Blood Supply
- Allows muscles to contract very quickly
- e.g., eye muscles
Fast Twitch
Form myelin sheaths around axons in the PNS
Schwann Cells
Form myelin sheaths around axons in the CNS
Oligodendrocytes
Space between Schwann Cells
Nodes of Ravier
Space between neurons
Synapse
Various cells that nourish and support neurons
Neuroglial Cells
Nerves of the PNS
- Cranial
- Spinal
Nervous System that Controls Voluntary Activities
Somatic
Nervous System that Control Involuntary Activities
Autonomic
- conduct Impulses from PNS to CNS
- have sensory receptors on the end of them
Sensory Nerves (Afferent)
- conduct impulses from CNS to effectors
- control voluntary and involuntary activities
Motor Nerves (Efferent)
- form links between CNS neurons (integration)
- create sensations, thoughts, feelings, memory, decisions
Interneurons (associations)
Neuroglial cells that provide structural support and form scar tissue
Astrocytes
Neuroglial cells that perform phagocytosis
Microglia
Regeneration of PNS Axons
- Distal Portion Regenerates
- Proximal Portion May Regenerate Slowly
Regeneration of CNS Axons
- Unlikely Due to Lack of Neurolemma and Oligodendrocytes’ Lack of Proliferation
Ion Distribution of a Resting Neuron
- High Na+ Outside the Cell
- High K+ Inside the Cell
Cause of Resting Neuron’s Negative Charge
Na+/K+ Pump (Active Transport)
- 3 Na+ Pumped Out for Every 2 K+ that Diffuse In
Do K+ or Na+ Diffuse across a nerve cell membrane more easily?
K+
The several subthreshold stimuli that added together reach the cell’s threshold potential
Summation
1) Threshold Potential Reached
2) Na+ Rush into the Cell (Cell Becomes More Positively Charged)
3) K+ Leave the Cell (Cell Becomes Negatively Charged Again)
(Sequence Moves Down the Axon Toward the Synaptic Cleft)
Action Potential (all or none response)
Ions a cells becomes more permeable to during an action potential
Na+
Time after a nerve impulse is generation in which the nerve cannot be stimulated
Refractory Period
When an action potential jumps from node of Ranvier to node of Ranvier
Saltatory Conduction
The neurotransmitters that relieve pain
- enkephalins
- beta endorphins
Neurotransmitter that transmits pain impulse
substance P
Neurotransmitter/Ion that is released into a synapse from from the synaptic knob of the presynaptic neuron to the postsynaptic neuron
Ca+
Function of Ca+ in Nerve Impulse
When the nerve impulse reaches the synaptic knob, Ca+ diffuse into the synaptic knob and neurotransmitters from vesicles inside the knob are released into the Ssnapse
Fate of Excess Neurotransmitters in a Synapse
Decomposition by an Enzyme or Reuptake
Function of Neurotransmitters (e.g., neuropeptides)
Stimulate or Inhibit Postsynaptic Neuron
