Nervous system functional anatomy Flashcards
1
Q
What is the nervous system responsible for?
A
- sensing
- regulating
- reacting to internal and external environment
2
Q
What does the nervous system have?
A
- Quicker response than the endocrine (hormonal) system
- Internal / external perception (entero/exteroperception)
- Internal and external communication
3
Q
What is the nervous system comprised of?
A
- brain
-spinal cord - nerves
4
Q
What is the basic functional unit of the nervous system?
A
- nerve cell/neurone
5
Q
How are neurones function supported?
A
- by glial cells
6
Q
What does the brain develop from?
A
- develops from the embryonic neural tube
7
Q
What are the different parts of the brain?
A
- forebrain
- midbrain
- hindbrain
8
Q
What happens in the forebrain?
A
- receives, integrates sensory information from nose, eyes and ears
- in land-dwelling animals it contains the highest integrating centres
9
Q
What does the midbrain do?
A
- coordinates reflex responses to sight and sounds
10
Q
Does does the hindbrain do?
A
- reflex control of respiration, blood circulation, other basic tasks
- in complex vertebrates, coordination of sensory input, motor dexterity and possibly metal dexterity
11
Q
Where is the olfactory lobe located?
A
- part of the forebrain
12
Q
What is the cerebrum?
A
- two hemispheres (paired lobes), wrinkled in some species
13
Q
What is the cerebrum responsible for?
A
- initiation of voluntary movement and coordination through integration of signals from balance organs, eyes and ears
- sensory perception
- memory, integration, planning
- in some species = self-awareness, language and personality
- posture
14
Q
What is the thalamus?
A
- paired midline structure
15
Q
What is the thalamus?
A
- relay station between brainstem and cerebrum for sensory input and outgoing commands
- regulation of consciousness, sleep, alertness
16
Q
Where is the hypothalamus located?
A
- under the thalamus
17
Q
What does the hypothalamus do?
A
- controls many homeostatic functions, via the pituitary gland
18
Q
What does the midbrain do?
A
- helps coordinate reflex responses to sight and sound
19
Q
What does the pons and medulla oblongata do?
A
- basic, life-sustaining and life-preserving activities such as breathing circulation, vomiting
20
Q
Where are the 12 important pairs of nerves originated?
A
- originating from underside of brain
21
Q
How are the cranial nerves named?
A
- named rostral to caudal with roman numerals
22
Q
The spinal cord is continuous with …
A
- the brainstem
23
Q
Where does the spinal cord start?
A
- starts between last pair of cranial nerves and first pair of spinal nerves
24
Q
Spinal nerves exit between each …
A
- vertebrate
25
The spinal cord doesn't grow as much as vertebral column - how does it grow?
- stops at different levels between species
- spinal nerves carry on caudally to exit at right place
- called cauda equina
26
There are cervical and lumbar enlargements - why are these here and what are these called?
- where's nerves to limbs arise (more neurons)
- brachial plexus (C6-T2)
- lumbosacral plexus (L4-S3)
27
What species are missing the cervical and lumbar enlargements?
- snakes
28
What is a neurons job and how does it do this?
- job is to communicate with other cells
- does this by transmitting impulses/action potentials
29
What does the soma possess?
- dendrites
- axon
30
What can differ between neurons?
- Arrangement, number and length of processes can differ (e.g. unipolar, bipolar, multipolar)
31
What is an action potential?
- wave of depolarisation
32
What does myelination help with?
- increases the speed of transmission
= saltatory effect
33
what does an action potential trigger?
- opens ion channels
- most commonly permitting net Na+ entry
34
Where are nerves located?
- PNS
35
What are bundles of neurone axons in the CNS called?
- tracts
36
Myelination of axons is achieved by different cells in the PNS and CNS - describe both:
- PNS – a separate Schwann cell
- CNS – arms of a myelin-forming oligodendrocyte
37
What happens where oligodendrocytes are destroyed by Schwann cells are not?
- multiple sclerosis
38
what system has nerves of which some are not myelinated?
- PNS
39
Neuronal connections are called synapses - where can these be?
- Can be axon-to-axon, axon-to-cell body, or axon-to-dendrite
- Can also refer to neuromuscular junction
40
What are synapses?
- Synapses are a small gap between the cells
41
If AP cannot usually cross synapse gaps then what happens?
What are the exceptions?
- Depolarisation cannot spread to a different cell
- (Some exceptions of electrical synapses)
42
What crosses a synapse gap instead?
- a chemical messenger = neurotransmitter
43
How are neurotransmitters sent across a synapse?
- AP causes pre-synaptic neurone to release neurotransmitter
- Diffuses across synapse
- Binds to post-synaptic neuron
- Variety of drugs and toxins also act at synapses
44
Where is grey matter found?
- outside the brain but inside the spinal cord
45
What is grey and white matter?
- Grey = predominantly neuronal cell bodies
- white = myelinated axons of neurones
46
What are clusters of cell bodies within white matter called and are closely associated with what?
- nuclei
- specific functions
47
What are bundles of axons running together called? and where can they be found?
- called tracts in spinal cord
- nerves outside of spinal cord
48
What are neuroglia?
- cells that surround neurons
49
Give examples of neuroglia?
- Oligodendrocytes and Schwann cells
- Astrocytes
- Microglia
50
Astrocytes functionally important and most abundant what do they do?
- Provide structural and functional support
- Absorb excess neurotransmitters
- Form blood-brain barrier
51
What are microglia?
- specialised macrophages
52
What are glial cells capable of?
- mitosis
- source of brain tumours
53
Neurons cant divide - what does this mean?
- if they are damaged they can't replace themselves
54
What is the nervous system protected by?
- enclosed by bone
- skull and vertebral column
55
What are the three protective membrane (meninges)?
- Dura mater
- Arachnoid mater
- Pia mater - stuck to the brain and contains vessels for nourishment.
56
The blood-brain barrier forms protection - it contains capillary walls and astrocytes - what do these do?
- Tight junctions stop substances passing between cells
- Selective transport through cells by membrane proteins
57
Cerebrospinal fluid (CSF) surrounds brain and spinal cord - what does it do?
- Cushioning impacts
- Buoyancy (brain floats, prevents ischaemia)
= Some nourishment
58
What is the ventricular system?
- system of cavities within CNS
59
What is cerebral spinal fluid secreted from?
- secreted by ependymal cells & choroid plexus
60
What is CSF and what does it contain?
- Network of blood vessels inside brain ventricles
- Super filtrate of blood (selective transport of BBB)
- Very low protein, few cells
- Contains glucose and minerals, helps nourish nervous tissue
61
How does CSF circulate?
- CSF circulates though brain ventricles, central canal of spinal cord, and subarachnoid space and eventually reabsorbed into the blood
62
Where is blood pooled before distribution to the brain?
- In all species, blood is pooled into the cerebral arterial circle (circle of Willis) before distribution to the brain
63
Why are there so many arteries to brain?
- so if one gets cut off there is still a blood supply to the brain
64
There are species variation in arrangement of blood vessels supplying circle - what supplies dogs and horses?
- From internal carotid artery
65
Species variation in arrangement of blood vessels supplying circle - what can also supply circle?
- From external carotid -> maxillary artery (others)
- Also from vertebral artery -> basilar artery
66
What makes up the anatomical/topographical classification?
- CNS
- PNS
67
What makes up the PNS?
- Cranial nerves
- Spinal nerves
- Ganglia
68
The nervous system can be functionally subdivided on the direction of nerve transmission - what are these?
- afferent
- efferent
69
What direction are afferent nerves?
Where can they be found and what can they be called there?
- towards spinal cord or specific brain regions
- Afferent are Arriving nerve axons
- Within spinal cord, can be called ascending
- Sometimes also termed ‘sensory’
70
What direction are efferent nerves?
Where can they be found and what can they be called there?
– away from spinal cord or specific brain regions
- Efferent are Exiting nerve axons
- Within spinal cord, can be called descending
- Sometimes also termed ‘motor’
71
As well as general afferent and efferent components, there is also special afferent - what are these for?
- Concerned with special senses (taste and smell, vision, hearing and balance)
72
What is the somatic NS?
– “voluntary nervous system”; senses and controls body relative to external environment
73
What does the somatic NS do?
- Sensory perceptions (e.g. touch, pressure, heat, pain, proprioception)
- Special senses (vision, balance, hearing)
74
What does the somatic NS have and what is it related to?
- Motor neurones to skeletal muscles (upper and lower motor neurones)
- Related ascending and descending pathways in the CNS
75
What is the visceral NS?
– “involuntary nervous system”; senses and maintains the internal environment within permissible limits
76
What does the visceral NS do?
- Sensing internal environment (e.g. receptors in organs and blood vessels)
- Special senses (taste and smell)
- Adjusting internal environment through innervation of organs
- Hypothalamus is an important integration centre
- Hypophysis (pituitary gland) also produces and stores important hormones
77
classification can be used in combination - Some nerves contain neurone axons of different NS components - give an example
- E.g. spinal nerves have both afferent (sensory) and efferent (motor) axons
