Nervous systems Flashcards
(54 cards)
1
Q
Terminology
A
cell body
dendrites
axon
synaptic terminals
synaptic transmission
2
Q
What are interneurones?
A
- located between neurones and form a connection between other neruones
- increase the number of synapses
- e.g. relay neurones, association neurones, connector neurones
3
Q
Describe the nervous system in hydra
A
- simple nerve net with no central nervous system
- APs can be conducted in all directions (bidirectional)
4
Q
Describe the nervous system in jellyfish
A
- more complex nerve nets
- sponatenous rhythmic activity
5
Q
Describe the nervous system in star fish
A
- modified nerve net with control of limb movements coordinated by the neural ring
- radial nerves can control movements of each limb individually
6
Q
Describe the trends in the evolution of nervous systems
A
- increase in number of nerve cells
- concentration of nerve cells into ganglia, ganglia into brains, nerves into nerve cords
- development of functional speciality
- localisation of specific functions in different parts of the nervous system
- development of interneurones and more complex synaptic contacts
- development of head bearing sense organs
- development of ventral nerve cord
7
Q
Describe the consequences of segmentation
A
- development of segmental ganglia to control locomotion
- coordination of movement between adjacent segments
8
Q
Describe the nervous system in arthropods
A
- have connectives = ganglia joined by connecting nerves
- have an autonomic nervous system which innervates the viscera of the body
9
Q
Describe how movement in arthropods in coordinated
A
- receiving sensory information from a defined part of a body segment
- activating dorsal/ventral or left/right limb muscles in response
- using central pattern generators (CPGs) - repeated rhythmic motor output independent of sensory stimulation
- interconnections between segmental ganglia (connectives) can propagate activity along the length of the ventral nerve cord
10
Q
Describe the nervous system of a molluscan
A
organised into ganglia:
- buccal - feeding
- cerebral - coordination
- pleural - respiration
- pedal - movement
^^ all in the brain
- parietal - ‘peripheral’
- visceral - organs
11
Q
Describe the human like intelligence of octopi
A
- gets food, clears front of its den, arranges rocks to cover entrance
- opens childproof caps on pill bottles
- playing by blowing jets of water
- can recognise human caretakers
- solving difficult problems using objects of differing colours and shapes
12
Q
List the three primary brain vesicles in the vertebrate CNS
A
- prosencephalon (forebrain)
- mesencephalon (midbrain)
- rhombencephalon (hindbrain)
13
Q
List the five secondary brain vesicles in the vertebrate CNS
A
- telencephalon
- diencephalon
- mesencephalon
- metencephalon
- myelencephalon
14
Q
Describe the features of ‘lower’ vertebrate brains
A
- large areas devoted to olfaction
- importance of optic lobes in fish and amphibians
- increasing size of cerebrum
- cerebral cortex consists of 3 layers
15
Q
Describe the key features of the mammalian brain
A
- folding of the cortex
- development of six layered neocortex
- enlargement of the cerebellum
- reduction of the olfactory system
16
Q
What is the difference between white and grey matter in vertebrate CNS tissue
A
white matter = myelinated axons
grey matter = collections of cell bodies
17
Q
Describe how swimming in lampreys is coordinated
A
- CPGs on each side of each spinal cord segment
- each half of spinal cord can generate basic rhythmic drive for locomotion
- connections between left and right sides ensure co-ordination
- CPGs controlled by locomotor command centres in brainstem
- brainstem locomotor command centres controlled by basal ganglia in the cerebral hemisphere
18
Q
What is the function of Mauthner neurones (M-neurones)
A
- responsible for the ‘fast escape’ in bony fish
- detect vibration by sensory input
- axon of the m-neurone crosses the midline and extends throughout spinal cord
- collaterals contact interneurones and motor neurones at all spinal levels
- unilateral muscle contraction
19
Q
Describe the evolution of the cerebellum during the transition onto land
A
vestibulocerebellum - balance
spinocerebellum - body raised off ground
neocerebellum - connected to cerebral cortex for motor coordination
20
Q
List the four phases of the step cycle in cats
A
- flexion
- first extension
- second extension
- third extension
21
Q
Describe the neuroanatomy and neurophysiology of walking
A
- spinal reflexes
- inhibition/stimulation of antagonistic muscle groups - flexors vs extensors
- co-ordination of movement of more than one joint
- sensory feedback controls rate of stepping
- supra-spinal control –> ascending sensory pathways run from spinal cord to sensory cortex in cerebral hemisphere –> neighbouring motor cortex, descending motor pathways exert control of motor neurones in spinal cord
22
Q
Describe the neuroanatomy of bird song
A
there is a complex interconnection of nuclei and tracts in the bird brain which control the syrinx enabling the production of song
23
Q
List the components of the CNS
A
brain and spinal cord
24
Q
List the components of the PNS
A
cranial nerves and spinal nerves
25
What is the difference between the somatic and autonomic nervous system
somatic - controls skin and skeletal muscle
autonomic - controls viscera (smooth and cardiac muscle)
26
Where are sensory and motor neurones found in the spinal cord?
sensory = dorsal horn
motor = ventral horn
27
What is the dorsal column ascending sensory pathway?
- at the back of the spinal cord
- sensory information processed by sensory neurons with cell bodies in the dorsal root ganglia
- ipsilateral communication initially
- neurons decussate at the medulla oblongata - now contralateral
28
What is the spinothalamic ascending sensory pathway?
- information from the spine up to the thalamus
- sensory information processed by primary sensory neurons with cell bodies in the dorsal root ganglia
- decussates at point of entry (L5)
- synapses with another neuron to create a contralateral pathway
- information passes up to the thalamus
29
Describe the organisation of the spinal cord
- interneurones connect functionally related lower motor neurones
- descending pathways are afferent to lower motor neurones
30
List the two spinal nerves located in the posterior sensory root
- general sensory afferent (GSA) - discriminative touch, proprioception, pain
- General Visceral Afferent (GVA) - sensation from the viscera
31
List the two nerves located in the anterior motor root
- General Somatic Efferent (GSE)- motor to skeletal muscles
- General visceral efferent (GVE) - motor to viscera
32
What is the corticospinal descending sensory pathway?
- tract passes through pyramidal structures of the medulla and decussates
- control over lower motor neurones that innervate skeletal muscles
- non-stereotyped (purposeful) movements
33
What is the meaning of somatotopy?
the orderly arrangement of the nervous system in relation to the parts of the body
34
List the main principles of mammalian brains
1. have topographic maps representing anatomical organisation
2. specific brain regions tend to have specialised functions
3. greater umber of neurons generally means more integration can occur
4. neural circuits are plastic
5. neurogenesis is confined to specific areas
35
List 2 examples of inter-hemispheric commissures
- corpus callosum - divides into left and right
- anterior commissure
36
Describe the cerebellum
- extrapyramidal system - for stereotypes movements
- functions in initiating, timing and terminating movements
- co-ordinates motor output
37
List 3 areas of grey matter in the hemisphere
- basal ganglia
- thalamus
- hypothalamus
38
Describe how extrapyramidal motor control is cooridnated in the basal ganglia
major inputs received from:
- cerebral cortex
- thalamus
- brainstem
major outputs to:
- thalamic nuclei
- cortex
- brain stem
39
What is the thalamus?
- relays sensory pathways to cerebral cortex
- activating the cerebral cortex - sleep and consciousness
- emotional effects generating autonomic activity
- cooridnation of visual and motor activity
40
What is the hypothalamus?
- responds to physiological, environmental and emotional changes that affect autonomic nervous system
- part of the limbic system --> involvement in thirst, hunger, appetite, reproduction
- maintenance of homeostasis
- neuroendocrine control - the pituitary gland
41
Describe the composition of the brainstem
midbrain
pons
medulla oblongata
42
Describe the functions of the brainstem
- functional composition of cranial nerves
- conveying sensory information to the cortex
- conveying motor control from the cortex to motor neurones
- cerebellar connections
- regulation of the autonomic nervous system
- visual and auditory reflexes
- alertness and consciousness
- breathing
43
Describe the areas of the brain involved in movement
- cortex - planning of voluntary movement
- basal ganglia - enhance desired movements and inhibit unwanted movements
- thalamus - relays sensory information to cerebral cortex
- brainstem - conveys sensory information to cortex and motor information to lower motor neurones
- cerebellum - coordinates motor outpu
44
List the key components of a somatic reflex arc
- sense organ
- afferent neuron
- synapse
- efferent neuron
- neurotransmitter junction
- muscle
45
Describe the sequence of events that occur during the knee jerk reflex
1. stimulate patellar tendon
2. activates stretch receptors or muscle spindles within extensor muscle
3. activates sensory neurone
4. extensor muscle contracts
5. flexor muscle relaxes
- checks lower motor neurones are functional
- reciprocal inhibition occurs in the spinal cord
46
Describe the events that occur during the flexor/crossed extensor reflex
- both sides of the body
- removing foot from stimulus --> flexor contracts and extensor relaxes
- other side of the body stabilises --> flexor relaxes and extensor contracts
47
List the basic components of autonomic control
- afferent neurone
- CNS
- interneurones
- autonomic preganglionic neurone
- autonomic postganglionic neurone
(two efferent neurones)
- effector
48
Describe the neurotransmitters and receptors involved in the sympathetic nervous system
preganglionic transmitter - acetylcholine
postganglionic receptor - nicotinic AChR
postganglionic transmitter - noradrenaline
target tissue receptors - alpha- or beta- adrenergic receptors
49
Describe the neurotransmitters and receptors involved in the parasympathetic nervous system
preganglionic transmitter - acetylcholine
postganglionic receptor - nicotinic AChR
postganglionic transmitter - acetylcholine
target tissue receptors - muscarinic AChR
50
Describe the parasympathetic outflows from the CNS
1. cranial: four cranial nerve nuclei - controlling secretory glands in the head, two intra-ocular muscles of the eye
2. sacral spinal cord S2,3 and 4 - the emptying nerves controlling the large bowel/anus, the bladder and erectile tissue of the genitalia
51
Describe the sympathetic outflow from the CNS
lateral horn of the spinal cord in:
- segments T1-L2(3)
- preganglionic axons synapse
- either in paravertebral ganglia or prevertebral ganglia
52
Describe the mechanisms that occur during the light reflex
- a function of ANS in the eye
- the afferent neuron is a projection of the optic nerve to the oculomotor nucleus
- short postganglionic fibres travel to the circular muscles of the iris to cause them to contract and narrow the pupils
53
Describe the sympathetic reflexes contributing to thermoregulation
1. reflex increases sympathetic discharge to sweat glands --> sweating
2. reflex decreases sympathetic discharge to cutaneous blood vessels --> vasodilation in skin
54
What is the enteric nervous system?
the innervation of the GI tract - is intrinsically controlled in the intestinal wall
