Introduction to the CNS, its Neurotransmitters and Blood Brain Barrier Flashcards
Where does the spinal cord start/end?
foramen magnum to L1/L2
What structure do spinal nerves exit the spinal cord through?
vertebral foramen
What is the last structure of the spinal cord?
conus medullaris after which you will find the Cauda Equina
What causes the enlargements of the spinal cord and where are they?
- cervical and lumbosacral regions
- caused by increased amounts of grey matter due to increased axons which innervate upper limbs (cervical) and lower limbs(lumbosacral)
Which nerves travel anterior dorsal horn and which travel posterior dorsal horn?
motor = anterior sensory = posterior
What is the function of the brainstem?
connects the ascending and descending tracts of the spinal cord to higher centres within the brain
Which cranial nerves have nuclei within the midbrain?
III (oculomotor)
IV (trochlear)
What is the function of the midbrain?
- holds nuclei of two cranial nerves and Edinger-Westphal nucleus
- holds neurones responsible for control of reflex movements of eyes, head and neck in response to visual and auditory signals
Which cranial nerve nuclei can be found in the Pons?
- Motor nucleus of V (trigeminal)
- Sensory nucleus V (trigeminal)
- Nucleus of VI (aducent)
- Nuclei for VIII (vestibulocochlear)
- Nuclei needed for respiration
Which cranial nerve nuclei can be found in the Medulla oblongata?
- Motor nuclei for XI
- Motor nuclei for XII
- Nuclei for respiration (X), control of BP (X & IX) and HR and digestion (X)
How does the cerebellum function?
- receives peripheral info regarding proprioception, muscle tone, head position and visual and auditory info
- compares and integrates info with info from cortex
- adjusts any motor plans using info (allowing you to make adjustments will moving)
- coordinates and predicts movement
What are the three major functions of the cerebellum?
- maintenance muscle tone
- maintenance of upright posture with respect to position
- associated with movements to make sure they are properly grouped for the performance of selective responses that require specific adjustments
What neurones are leaving the CNS?
Efferent
What are the divisions of the efferent neurones?
- Autonomic
- Somatic
- enteric (can work independently but can also be influenced by autonomic and somatic)
What are the divisions of the autonomic neurones?
- sympathetic
- parasympathetic
Which neurones send information back to the CNS?
Sensory (afferent)
What do somatic neurones do?
innervate skeletal muscle
What are the embryological regions of the forebrain?
- Telencephalon (becomes cerebral hemisphere)
- Diencephalon (stays in adults)
What are the embryological regions of the midbrain?
- Mesencephalon (just called midbrain in adults)
What are the embryological regions of the hindbrain?
- Metencephalon (becomes cerebellum and pons)
- Myelencephalon (Medulla oblongata)
What lobes are found either side of the central and lateral sulcus?
Central - parietal and frontal
Lateral - Temporal and frontal
What structures are found just anterior and just posterior to the central sulcus?
- precentral and postcentral gyrus
What separates the two hemispheres?
Longitudinal cerebral fissure
What sulcus separates parietal and occipital lobes
parieto-occipital sulcus
Where are the primary motor areas located?
precentral gyrus (frontal lobe)
What is the main function of the frontal lobe?
- regulates and initiates voluntary motor behaviour
- expressive and motor aspects of language processed on lateral surface (Broca’s speech area)
Where is the prefrontal area?
- frontal pole of frontal lobe
What is the prefrontal area responsible for?
- connects to all other lobes via fasciculi and has access to sensory processing and memory
- monitors behaviours and controls higher processes
- prefrontal association areas concerned with emotion, motivation, personality and judgement
What is the main function of the parietal lobe?
- regulating somatosensory functions (contains primary somatosensory area in postcentral gyrus)
- processing and perception of pain, temperature and proprioception
- Wernickes area - receptive or sensory aspects of language
- spatial orientation and perception
How are the somatosensory and primary motor areas arranged?
somatotopically
Occipital lobe functions?
- processes visual info
- visual association areas found around lateral surface of lobe
What structure separates occipital and temporal lobes?
calcarine sulcus
Functions of the temporal lobe?
- processing auditory info
- superior gyrus area used to interpret what we hear
- lateral surface is for perception of language
- anterior medial important in complex parts of learning memory and emotion
What are the symptoms of Wernickes aphasia?
- difficulty understanding written or spoken language
- can generate speech but language is meaningless
What are the symptoms of Broca’s aphasia?
- difficulty generating written or spoken language
- little difficulty with language comprehension
What structures make up the diencephalon?
- Thalamus
- epithalamus
- subthalamus
- hypothalamus
What is the function of the thalamus?
(sensory switchboard) receives information from spinal cord, vestibulocochlear and optic nerve and sends it to appropriate area of brain
(olfaction does not go through thalamus)
What is the function of the hypothalamus?
controls homeostatic, autonomic and endocrine functions
What is the function of the epithalamus?
- pineal body produces melatonin and maintains circadian rhythm
- habenular nucleus - regulates dopamine and serotonin and has role in addiction and motivation
What is the limbic system?
- interconnected and interacting structures which play significant role in emotional behaviours
- role in memory and learning
What structures make up the limbic system?
- thalamus
- fornix
- amygdala
- hippocampus
- parahippocampal gyrus
- cingulate gyrus
Where in the hippocampus will neurogenesis occur?
dentate gyrus
What is neurogenesis?
- plays role in formation of new memories
- modulates symptoms of stress and depression
What can lesion in hippocampus cause?
- amnesia
- affects ability to store long term memories
What is the function of the amygdala?
- ability to feel strong emotions, emotional memory and learning
- role in drive related behaviours e.g. emotional learning and behaviour, fear and conditioning and reward
- recognises and interprets emotional behaviour signals from others
Where are the basal nuclei (ganglia) located?
under cortical layer within the forebrain, diencephalon and midbrain
What are the different basal nuclei?
- Caudate nucleus
- putamen
- globus pallidus
- sub thalamic nucleus
- substantia nigra
(group of interconnecting nuclei)
What is the function of the basal nuclei?
critical role in initiation and control of voluntary movement
What are the four types of neurotransmitter?
- Amino Acid
- Biogenic amines
- purines
- neuropeptides
What cells synthesise glutamine?
- astrocytes
- converted into glutamate by neurones
What are the more common amino acid neurotransmitters (are they excitatory or inhibitory)?
Glutamate - excitatory
GABA - inhibitory
Glycine - inhibitory
What are the more common biogenic amines (are they excitatory or inhibitory)?
Dopamine (D1 rec) - excitatory Dopamine (D2 rec) - inhibitory Noradrenaline - Excitatory Adrenaline - Excitatory Serotonin - Excitatory/inhibitory Histamine - Excitatory
What functions is dopamine associated with?
- movement
- emotion
- motivation
- reward
Used in forebrain
What functions is serotonin associated with?
- mood
- emotion
- sleep
- many homeostatic pathways
What is the main function of histamine as a neurotransmitter?
Wakefullness
Give an example of Purine neurotransmitter?
ATP - Excitatory/inhibitory
What are some of the more common neuropeptides?
Substance P - Excitatory
Metenkephalin - Inhibitory
Opioids - Inhibitory
Adrenocorticotropin - Excitatory
What neurotransmitters are involved in the pain pathways?
Substance P - excitatory
Opioids/metenkephalins - inhibitory
What molecules will most easily get through the blood brain barrier?
Smaller and more lipid soluble
What is the function of the blood brain barrier?
isolates CNS from blood as a form of protection
What structures make up the blood brain barrier?
Capillary (inside)
- endothelial cell
- continuous basement membrane
- foot processes of astrocytes adhere to basement membrane
What is the function of the astrocytes?
rid of any pathogens which do make it past the previous layers
What adaption is present in the blood brain barrier which isn’t in the peripheral circulation?
tight junctions allowing nothing through
Where is the blood brain barrier not present allowing substances through?
- 4th ventricle and hypothalamus
- capillaries here contain fenestrations
Why are the fenestrations in the blood brain barrier essential?
- neurotransmitters able to monitor the blood plasma
- to send information to hypothalamus
