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to Biol 1020Dr. D. Yordy
Course Outline : Part 2
Detailed structure
Fluid-mosaic model
components
phospholipids
proteins
peripheral
integral
functions
carbohydrates and glycoproteins
importance of asymmetry
Membrane junctions
tight
desmosome
gap
Membrane functions
Compartmentalization, recognition, signal reception, enzymatic activity
Semi-permeability
Movement of materials across
Passive processes
Osmosis and Tonicity
Diffusion
membrane solubility
size
charge
non-polar vs. polar materials
channels
effects of size
effects of number
types
receptor sensitive
stretch sensitive
voltage sensitive
effects of electrochemical gradients
Passive, carrier-mediated : facilitated diffusion
Active, carrier mediated: active transport
Energy/ ATP requirement
Example: sodium/potassium pump
Development of the membrane potential
Sodium/potassium pump
Difference between sodium and potassium permeability
Trapped negatively charged proteins
Other ways to move materials
Bulk flow
Endo- and Exo-cytosis cytosis
Physiology of the nervous system
Comparison of the nervous and endocrine systems
Divisions of the nervous system
Central nervous system
Peripheral nervous systems
afferent division
efferent division
somatic
autonomic
sympathetic
parasympathetic
The neuron
Generalized function
Generalized structure
Types and location in the nervous system
afferent or sensory neurons
association or interneurons
efferent or motor neurons
Other definitions
myelination
nodes of Ranvier
nerves
nerve tracts
ganglia
nuclei
The neurolemma and the membrane potential
Development of the membrane potential
How a neuron responds to a stimulus - the action potential
resting potential
graded potentials
threshold
depolarization
repolarization
hyperpolarization
The action potential as an all-or-none event
The action potential - what happens at the cellular level
depolarization- sodium influx
repolarization - potassium efflux
propagation of the action potential
operation of voltage-sensitive channels
Factors that influence the rate of impulse conduction
nerve diameter
myelination/ nodes of Ranvier
saltatory conduction
multiple sclerosis
Factors that influence excitability
pH
electrolytes
The refractory period
absolute
relative
consequences of the refractory period
Role of the sodium-potassium pump
The synapse
definitions: the synapse, pre- and post- synaptic cells
communication across the synapse
calcium-dependent release of neurotransmitters after an action potential
diffusion of the neurotransmitter across the synapse
specific binding to post-synaptic cell receptors
receptor operated channels
inhibitory (hyperpolarizing) vs excitatory (depolarizing) synapses
IPSPs and EPSPs
synaptic delay
synaptic integration- The GPSP
turning off the signal- the fate of the neurotransmitter
enzymatic degradation - ex. acetylcholinesterase
recycling- transport back into the pre-synaptic cell
diffusion away from the synapse
fatigue- over stimulation of pre-synaptic neuron
Skeletal muscle structure
Excitable
Nucleated cells or fibrils
Myofibrils
Sarcomeres- functional units of skeletal muscle
precise arrangements of the protein filaments: actin and myosin
troponin and tropomyosin
Myosin structure and enzymatic (ATPase) activity
Actin structure and the relationship to tropomyosin and myosin
Calcium binding to troponin and the consequences
Cross-bridge formation
ATP needed to do contractile work
Innervation
Somatic motor neurons
The motor unit- a motor neuron and all the muscle fibers it innervates
The neuromuscular junction
Message reception- myoneural junction
Release of the neurotransmitter- acetylcholine at the axon terminal
Binding of acetylcholine to nicotinic type 2 receptors on the motor end plate
Development of the endplate potential (EPP) - sodium influx - receptor sensitive
channels
EPP always an excitatory event- brings muscle fiber to threshold action
potential develops
Skeletal muscle cell action potential
Role of T-tubules, sarcoplasmic reticulum
Excitation coupling - participation of calcium ions
ATP
Requirements: myosin energized, break cross bridges, pump calcium back into
sarcoplasmic reticulum
Sources : glycolysis, oxidative phosphorylation
Turning off the contraction - acetylcholinesterase
The muscle "twitch"
Latent period
Period of contraction
Period of relaxation
Summation
Spatial: recruitment of motor units
Temporal: increased cytoplasmic calcium pool, tetanus
Fatigue
Lactic acid accumulation
Neuromuscular fatigue
Central fatigue
Type of skeletal muscle fibers
Oxidative (red) vs glycolytic (white)
Fast versus slow
Fatigue and the different muscle fiber types
Endurance versus strength
Effects of exercise on muscle fiber development