Overview of Nervous System Flashcards
What are the four functions of the nervous system?
- Gather sensory information from internal/external environment
- Integrate information for assessment and meaning
- Produce a response
- Regulate body homeostasis for optimal performance
What are the three types of neuron and what do they do?
- Afferent = takes information from PNS to CNS
- Interneuron = relays information
- Efferent = takes response from CNS to PNS
What are the components of a typical neuron?
o Dendrite = collects information
o Cell body = synthetic centre
o Axon = conducts action potentials from cell body to other neurons or effector organ
o Axon terminal = release neurotransmitter onto other neurons (or effector organ)
What are the six categories that most neurons fall into? (see picture in lecture notes for corresponding numbers)
o Sensory neurons (1) o Motor neurons (2) o Preganglionic autonomic neurons (3) o Postganglionic autonomic neurons (4) o Local interneurons (5) o Projection neurons (long interneurons) (6)
Where are glial cells found and what do they do?
Satellite cells - Support cell bodies in PNS Schwann cells - Secrete neurotrophic factors in PNS - Form myelin sheaths in PNS Oligodendrocytes - Form myelin sheaths in CNS Microglia (modified immune cells) - Act as scavengers to remove dead cells, etc in CNS Astrocytes (in CNS) - Provide substrates for ATP production - Help form blood-brain barrier - Secrete neurotrophic factors - Take up K+, water, neurotransmitters - Source of neural stem cells Ependymal cells (in CNS) - Source of neural stem cells Create barriers between compartments
How do glial cells contribute to neurological disease?
- Most brain tumours are gliomas o Glial cells can undergo mitosis Schwannoma, astrocytoma, ependymoma and oligodendroglioma - Epilepsy o Often caused by malfunction in glial cells (astrocyte scar) in a region where neuronal damage has taken place - Alzheimer's disease o Tau in astrocytes and oligodendrocytes - Multiple sclerosis o Autoantibodies attack oligodendrocytes
What are the anatomical axes/planes of the spinal cord?
- Dorsal = posterior
- Ventral = anterior
o Example dorsal horn is the posterior horn and where sensory axons enter
o Example ventral horn is anterior horn and location of lower motor neuron cell bodies
What is white matter? What is grey matter? What are nuclei and ganglia?
- Grey matter
o Neuronal cell bodies, dendrites, axon terminal, synapses and is highly vascular - White matter
o Bundles of myelinated axons mainly - Groupings of neuronal cell bodies
o Nucleus – cranial nerve nuclei in brainstem
o Ganglion – usually outside of CNS and sensory cell bodies such as the dorsal root ganglia
What are the 3 embryonic brain regions? What do these split into and what brain structures do they become later on?
Forebrain
- Splits into telecephalon (becomes cerebrum) and diencephalon (becomes diencephalon, e.g. hypothalamus, thalamus, epithalamus)
Midbrain
- Splits into mesencephalon (becomes midbrain - part of brainstem)
Hindbrain
- Splits into metencephalon (becomes pons and cerebellum) and myelencephalon (becomes medulla oblongata)
What does the adult ventricular system consist of?
- A series of interlinked fluid filled chambers
- 4 chambers – 2 lateral ventricles and then the 3rd and 4th ventricles
- Basal ganglia nuclei and thalamus are in close proximity to the ventricles
What are the cerebral lobes and their functions?
- Frontal lobe
-> Problem solving, emotional traits, reasoning (judgment), speaking, voluntary motor activity - Temporal lobe
-> Understanding language, behaviour, memory, hearing - Brain stem
-> Breathing, body temperature, digestion, alertness/sleeping, swallowing - Parietal lobe
-> Knowing right from left, sensation, reading, body orientation - Occipital lobe
-> Vision, colour perception - Cerebellum
-> Balance, coordination and control of voluntary movement, fine muscle control
(See image on lecture notes)
What are the Brodmann areas?
- Identified 52 distinct regions of the cerebral cortex
o Many based on neuronal organisation that have since been correlated with function
o 44-45 = Broca’s
o Part of 22 = Wernicke’s
o 1, 2 and 3 = primary somatosensory cortex
o 4 = primary motor cortex
(see image in lecture notes)
What are the cerebral cortexes?
- Specific regions within the lobes have specific functions o Many match up to the Brodmann areas - Motor cortex - Gustatory cortex - Olfactory cortex - Insula - Auditory cortex - Sensory cortex - Visual cortex (see image in lecture notes)
Where do primary motor and sensory signals come from? How are they separated? Which side of the brain controls which parts of the body?
Primary motor = frontal lobe - Primary sensory = parietal lobe - Separated by the central sulcus o Precentral gyrus and postcentral gyrus - Left cerebral hemisphere communicates with right side of body
When will Wernicke’s area light up in brain imaging? What about Broca’s area? How are these connected? Where are these located?
- Wernicke’s area
o Comprehension / understanding of written and spoken language
o Brodmann area 22 - Broca’s area
o Language production
o Brodmann area 44-45 - Connected by arcuate fasciculus (white matter tract)
- Both in dominant left hemisphere
- Right side has both areas as well but has different purpose
o Grammar, sentence construction emotion, inflection (right brain damage causes monotonous speech)
What do the left and right cerebral hemispheres control?
- Left cerebral hemisphere controls right side of the body
o But also logic, analysis of facts, understanding of production of language - Right cerebral hemisphere controls the left side of the body
o Imagination, rhythm, holistic thinking, non-verbal language, emotion in language
Which brain hemisphere is dominant?
Left (even in left-handed people)
What is the major tract, the corpus callosum?
- Corpus callosum connects cerebral hemispheres
o 250,000,000 axons - Extends from enlarged genu in frontal lobe to enlarged splenium in parietal lobe
(see lecture notes for images)
What is the major tract, the anterior commissure and internal capsule?
- Anterior commissure connects the temporal lobes
- Internal capsule runs between lenticular nucleus (basal ganglia) and thalamus / head of caudate
o Route through which information travels to and from cerebral cortex to subcortical sites
What is the thalamus?
- Lies on either side of the 3rd ventricle
o Forms wall of 3rd ventricle - Receives input from ALL areas of the nervous system
o Gateway to the cortex
What is the limbic system, what is its function, and what are its components?
- 5th lobe of the brain o Supports functions such as: Emotion, behaviour, long term memory and olfaction - Hippocampus o Spatial memory, learning - Amygdala o Episodic auto-biographical memory o Attentional and emotional processes o Social processing
Which situations may trigger the amygdala?
- Frightening situations—or even memories of such situations—activate the amygdala, as shown in this functional magnetic resonance image (fMRI) of the left side of the brain of a person experiencing fear.
What may result from damage to the limbic system>
- Damage to hippocampus from exposure to stress hormones or long-term glucocorticoids disrupts explicit memory
- Amygdala (Kluver-Bucy syndrome) not afraid of anything, forget things rapidly, place things in their mouths, strong sex drive and inappropriate
Where do most cranial nerves originate from? What do they consist of and what are their functions?
- Most of cranial nerves originate from brainstem
o Except CN I, II - Ascending and descending tracts
- Sympathetic descending axons
- Integrative functions (reticular formation)
How many cranial nerves are there? What are the cranial nerve nuclei?
- 12 pairs of cranial nerves
o 10 have motor and or sensory nuclei in brainstem - Medial-lateral location of nucleus is predicted by the sulcus limitans
o Sensory nuclei lateral, motor nuclei medial - Longitudinal location related to the attachment of the cranial nerve to brainstem region
o Rule of 4
