The Central Nervous System Flashcards
what are the two structures of the CNS
the brain and the spinal
What are some functions of the CNS
- subconscious regulation of internal environment
- emotions
- voluntary movement
-perception - higher cognitive functions eg. learning and memory
what are the three functional classifications of neuronal cells
- afferent neurons (mainly in PNS) have a sensory receptor on the peripheral ending
- interneurons (only in the CNS) are connector neurons that lie between afferent and efferent neurons, important for creating neural circuits (also high brain functions)
- efferent neurons lie within the CNS where they receive presynaptic inputs then travels to down efferent fibre to effector organ (efferent fibre is outside CNS)
what are glial cells
they are the non-neuronal cells of the nervous system that do not initiate/propagate action potentials they use chemical signals to communicate (the connective tissue of the brain)
what are the four types of glial cells
- oligodendrocytes form the myelin sheaths surrounding some neuronal axons of the CNS (Schwann cells in PNS)
- ependymal cells are ciliated and lie in the ventricles of the CNS producing Cerebrospinal fluid (CSF)
- astrocytes have a lot of functions: connective tissue holding neurons in place, establishing a blood-brain barrier, repair brain and spinal cord injuries, stop neurotransmitter activity, enhance synapse formation, take up excess K+
- microglia are immune cells of the CNS inactive until sensing pathological change
what are the four protective structures of the CNS
- the skull and vertebrae
- meninges (3 membranes that wrap and contain the CNS) consists of the dura mater, arachnoid mater, and pia mater
- cerebrospinal fluid acts as a shock absorber, also transfers materials between the blood and neural tissues (choroid plexuses create CSF)
- the blood-brain barrier is formed by endothelial cells joined by tight junctions that makes the exchange of materials into the CNS highly regulated
what is the difference between grey and white matter
- grey matter consists of nerve cell bodies, short interneurons, and glial cells (central canal with CSF)
- white matter consists of bundles of nerve fibres of axons
what are the different horns of grey matter
- dorsal horn is cell bodies of interneurons where afferent neurons terminate
- lateral horn is cell bodies of autonomic efferent nerve fibres
- ventral horn central bodies of somatic efferent neurons
what are the different tracts of white matter
- ascending tracts of afferent neurons
- descending tracts of efferent neurons
what is the dorsal root ganglia composed of
the cell bodies for afferent nerves
what are the regions of the spinal cord
cervical - thoracic - lumbar - sacral
what are the two key functions of the spinal cord
1) conduit for transmitting information between the brain and the periphery
2) integrating afferent/efferent inputs/outputs which bypass the brain (spinal reflexes) can be simple or acquired
what is a reflex arc (the five components?)
neuronal pathways for reflexes with 5 components:
1) skin receptors sense physical/chemical change in environment and produce action potential
2) the action potential is transmitted to the integrating centre
3) the interneuron (integrating centre) for simple reflexes are integrated within the spinal cord/brainstem (acquired reflexes require higher processing)
4) the response is transmitted through the efferent neurons
5) the target is reached (usually a muscle or gland)
what are the 5 regions of the brain we need to know
1) cerebrum (basal ganglia + cerebral cortex)
2) diencephalon (hypothalamus + thalamus)
3) forebrain
4) cerebellum
5) brainstem
what are the three sections of the brain stem
midbrain - pons - medulla oblongata
what are the 5 major functions of the brainstem
- houses cranial nerves
- controls vegetative functions (medulla oblongata)
- muscle reflexes involved in posture and equilibrium
- contains reticular activating system
- role in sleep
what is GABA
major inhibitory neurotransmitter that plays an important role in sleep
describe the structure and anatomical location of the reticular activating system
consists of reticular formation (networks of neurons through brainstem - thalamus) and ascending fibres that send signals to the cerebral cortex
what are the functions of the thalamus
- integrating centre for all sensory input on its way to the cortex (can influence the priority of signal processing)
name 5 functions of the hypothalamus
integration centre for homeostatic functions (links autonomic and endocrine system)
- production/secretion of pituitary hormones
- sleep/wake cycle
- autonomic nervous system coordinating
- uterine contraction and milk ejection
- fluid intake
- urine output/thirst
- emotion/behaviour
- body temperature
what connects the right and left hemispheres of the cerebral cortex, and is it composed of grey or white matter?
corpus callosum - grey matter
what are the four lobes of the cerebral cortex (where are they and what are their functions)
frontal lobe - voluntary motor activity + speech
parietal lobe - receiving and processing sensory input
occipital lobe - initial processing for vision
temporal lobe - vision and hearing
where is the somatosensory cortex and what does it do
anterior region of the parietal lobes processes somaesthetic input (touch, pressure, cold, heat, pain) and proprioceptive input (relative position of body parts and strength needed for movement)
where is the somatosensory cortex and what does it do
anterior region of the parietal lobes processes somaesthetic input (touch, pressure, cold, heat, pain) and proprioceptive input (relative position of body parts and strength needed for movement)
