nervous system Flashcards
(21 cards)
What are the two main divisions of the nervous system?
The Central Nervous System (CNS) and the Peripheral Nervous System (PNS).
What is the role of the Central Nervous System (CNS)?
The CNS integrates sensory information and coordinates bodily functions; includes the brain and spinal cord.
Why are neurones considered the functional units of the nervous system?
Neurones transmit and integrate electrical signals across the body, forming complex communication networks.
What is the electrochemical basis of the nerve action potential?
It is based on ion gradients across the membrane, with Na+ causing depolarization and K+ causing repolarization.
What is resting membrane potential and how is it established?
It is the electrical charge across a neuron’s membrane at rest (~-70 mV), maintained by ion channels and pumps.
How does an action potential propagate along a neurone?
It travels as a wave of depolarization followed by repolarization, moving from the axon hillock to terminals.
What role does myelin play in nerve impulse conduction?
Myelin increases conduction speed by enabling saltatory conduction between nodes of Ranvier.
Which cells are responsible for myelinating axons in the CNS and PNS?
Oligodendrocytes in the CNS and Schwann cells in the PNS.
What is the ‘all-or-nothing’ principle of action potentials?
An action potential either occurs fully if threshold is reached or not at all; it is not graded by stimulus strength.
What is the difference between absolute and relative refractory periods?
Absolute: no AP possible due to Na+ inactivation; Relative: AP possible with stronger stimulus due to K+ efflux.
What is a neuronal synapse?
A junction between neurons where signals are transmitted either chemically or electrically.
What are the two types of synapses?
Chemical synapses (most common) and electrical synapses (via gap junctions).
What do excitatory neurotransmitters do?
They depolarize the postsynaptic membrane, generating excitatory postsynaptic potentials (EPSPs).
What do inhibitory neurotransmitters do?
They hyperpolarize the postsynaptic membrane, generating inhibitory postsynaptic potentials (IPSPs).
What is synaptic integration?
The summation of EPSPs and IPSPs to determine if the neuron will fire an action potential.
What receptors does acetylcholine act on?
Nicotinic and muscarinic acetylcholine receptors (nAChRs and mAChRs).
What are the divisions of the Peripheral Nervous System (PNS)?
Autonomic Nervous System (ANS), Somatic Nervous System (SNS), and Enteric Nervous System (ENS).
What is proprioception?
The sense of the relative position of body parts and strength of effort used in movement.
What is the function of the Somatic Nervous System?
It controls voluntary movements of skeletal muscles.
What is the neuromuscular junction (NMJ)?
A specialized synapse where a motor neuron communicates with a skeletal muscle fiber to initiate contraction.
What is excitation-contraction coupling at the NMJ?
The process where a neural signal leads to muscle contraction via calcium release and actin-myosin interaction.
