PBL 3: David Hoyle -Nervous System Flashcards
What comprises the Central Nervous System?
- Brain and Spinal Cord
- Integrative and Control Centers
What comprises the Peripheral Nervous System?
- Cranial Nerves and Spinal Nerves
- Communication lines between the CNS and the rest of the body
What are the two divisions of the PNS?
- Sensory (afferent) division
- Motor (efferent) divisions
What comprises the Sensory (afferent) division of the CNS and what is its major function?
- Somatic and visceral sensory nerve fibers
- Conducts impulses from receptors to the CNS
What comprises the Motor (efferent) division of the PNS and what is its major function?
- Motor nerve fibers
- Conducts impules from CNS to effectors (muscles and glands)
What are the two major divisions of the motor division of the PNS?
- Autonomic Nervous System
- Somatic Nervous System
What comprises the ANS and what is its major function?
- Visceral motor (involuntary)
- Conducts impulses from the CNS to cardiac muscles, smooth muscle andd glands
What are the 2 divisions of the ANS and their functions?
- Sympathetic division: mobilizes body systems during activity
- Parasympathetic division: conserves energy, promotes housekeeping functions during rest
What comprises and is the major function of the somantic nervous system of the motor division of the PNS?
- Somatic motor (voluntary)
- Conducts impulses from the CNS to skeletal muscles
Draw the basic organization of the central and peripheral components of the nervous system
Somatic Neurotransmitters and receptors
Acetylcholine/Nicotinic
Sensory neurotransmitters and receptors
Acetylcholine/Nicotinic
Parasympathetic neurotransmitters and receptors
Preganglionic: Acetylcholine
Postganglionic: ACh
Preganglionic: Nicotinic
Postganglionic: Muscarinic
Sympathetic neurotransmitters and receptors
Preganglionic: Acetylcholine
Postganglionic: Noradrenaline, adrenaline (via medulla)
Preganglionic: Nicotinic
Postganglionic: a1/2. b1/2/3. Muscarinic
Draw the structure and effectors of nerve fibres for the somatic nervous system and each division of the ANS.
Functions of the Parasympathetic division of the ANS
SLUDGE
Salivation
Lacrimation
Urination
Defecations
Gastric Motility
Emesis
Functions of the Sympathetic division of the ANS
The four E’s
Excitement
Emergency
Embarassment
Exercise
Functions of the Enteric Nervous System
- Embedded in the GI lining
- GI functions
- Can function by itself
How are action potentials generated?
- A membrane potential is created through the maintenance of an ionic gradient between the intracellular and extracellular space
- [N+] high outside cell, [K+] high inside
- Na+/K+ ATPase pump maintains gradient
- Membrane potential roughly -70mV between outside and isnide of cell with the inside being more negative than outside
Neurotransmitter (non-direct) propagation of action potentials
- AP arrives at nerve terminal
- CA2+ diffuses into the nerve
- Influx of CA2+ promotes exocytosis of neurotransmitters
- Neurotransmitter diffuses across synaptic cleft
- Neurotransmimtter binds to ligant gated channels, causing Na2+ to move into the cell
Generation of the Action Potential
- Stimulus causes the opening of Na channels which causes Na to rush into the cell -inside of the cell becomes more positive and membrane potential rises from -70mv to -55mv
- Depolarization threshold is reached, more channels open causing +30mv
- At +30mv Na channels close and K+ channels open, allowing L to rush out of the cell. Inside of cell loses positive charge causing membrane potential to return to -70mv
- Membrane potential drops below -70Mv to to K-channel slow to close -hyperpolarization
Draw the time course and an action potential
AP propagation in unmyelinated nerves (Continuous conduction)
APs are generated at sites immediately adjacent to each other and conductions is relatively slow
AP propagation in myelinated nerves (saltatory conduction)
Myelin sheath acts as insulating, preventing leakage of charge from axon and allowing membrane voltage to change more repidly.
Current only pass out of membrane at nodes of Ranvier.
Highly concentrated Na+ channels at nodes
30 times faster, ‘leaping’
Derp you know this you have a degree in neuroscience derpderpderpderp derp derp derp derp derp.
