1
Q
somatic nervous system
A
- controls voluntary movements and lower order behaviour
- motor neurons have their cell bodies in the ventral horn of grey matter in the spinal chord
- axons of motor neurons leave the ventral root of the spinal chord and form peripheral nerves
- directly innervate skeletal muscle using Ach
2
Q
lower order behaviour (SNS)
A
- split into elementary behaviour (acts) and complex behaviour (patterns)
3
Q
elementary behaviour (SNS)
A
- reflex acts, where the effect is proportional to the stimulus
- fixed acts, where the effect is stereotyped/ ‘all or nothing’, as the synapses are electrical
4
Q
reflex acts e.g. tetrapod stretch reflex
A
- monosynaptic
- maintains balance
1. stretch receptors in muscle spindles embedded in muscle excited
2. sensory neuron excited, action potential to CNS
3. motor neuron excited at synapse, causes same muscle to contract to counteract stretch (NMJ)
5
Q
reciprocal innvervation
A
- if 2 antagonistic muscles contract at the same time, one of both could be damaged
- motor neuron of antagonistic muscle inhibited when reflex arc occurs
6
Q
fixed acts e.g. crayfish tail flip
A
- escape mechanism
- relies on bilateral pair of neurons, the lateral giant interneurons (LGIs)
- when the mechanoreceptive hairs on the tail fan of crayfish are stimulated, it performs a fast tail flip
7
Q
complex behaviour (patterns), fixed action patterns
A
- sequence of effector actions patterned in space and time
- uses distributed hierarchical control, where a lower centre of processing produces movement through central pattern activators (in spinal chord or ganglia) after central processes make the decision to perform that movement
8
Q
fixed action patterns e.g. locust wing muscle excitation
A
- alternating action potentials of depressor and elevator muscles
- rhythm generated in central pattern activators in ganglion, central control and peripheral input
9
Q
autonomic nervous system
A
- not under conscious control
- split into parasympathetic (rest and digest) and sympathetic (fight or flight)
10
Q
parasympathetic nervous system (ANS)
A
- promotes conditions favourable for resting and digesting
- long preganglionic neuron arises from craniosacral spinal chord and has a chemical synapse using ACh with a short postganglionic neuron in a terminal ganglion (close to target)
- neurotransmitter at effector is also ACh
11
Q
sympathetic nervous system (ANS)
A
- promotes conditions favourable for fight or flight
- shorter preganglionic neuron arises from thoracolumbar spinal chord and synapses with long postganglionic neuron at a sympathetic trunk ganglion using ACh
- neurotransmitter at effector is noradrenaline
12
Q
autonomic tone
A
- balance between rest and digest and fight or flight state
- organs undergo ongoing stimulation and sit somewhere between depending on the relative strength of this stimulation
13
Q
ANS - ACh receptors
A
- all autonomic ganglia have nicotinic receptors (excitatory)
- muscarinic receptors found in parasympathetic targets (inhibitory)
