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Summary lectures HNH-31706 Nutrition and the Brain (HNH31706)
This is a summary of all lectures of the course Nutrition and the Brain (HNH31706) from the WUR
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Lecture 1 – Basic principles brain functionThe brain consists of brain tissue and glia cells
Brain tissue: neurons (100 billion)
o Unipolar, bipolar, pseudo unipolar & multipolar
Multipolar: most abundant, consist of dendrites where the signal enters then
the cell body which accepts the signal and choses to precede and make it an
action potential or not (via node of Ranvier) and then the long axon towards
the synapse in the axon terminal
Glia cells: support the neurons, distinct functions
o Astrocytes: in the CNS, multipolar neuron with end feet prone in supporting
neurons in glucose and neuronal inflammation, maintain extracellular environment,
remove excessive neurotransmitter, direct neural growth, induce BBB in CNS
o Oligodendrocytes: in the CNS produce myelin, action potential
o Microglia: in the CNS regulate neuroinflammation (immune system of the brain),
immune surveillance and phagocytosis
o Ependymal cells: in the CNS, ventricles produce and circulate cerebrospinal fluid,
form the outer layer of the brain (skin-type surface cells)
o Schwann cells: in the PNS produce myelin
o Satellite cells: in the PNS, support maintain extracellular environment, remove
excessive neurotransmitter, direct neural growth
Neural communication: via synaptic transmission (neurotransmitters, pre-postsynapses) or action
potential (Na/K-pumps, membrane potential)
Action potential: from the cell body reaches down towards the axon terminal synapse where
they come to the end of the synapse vesicles filled with neurotransmitters (e.g. dopamine,
glutamate, serotonin) which are released into the synaptic cleft and then can reach other
neurons to precede the signal to this cell body or not (too low signal)
o Dopamine: Parkinson’s disease, addiction
o Serotonin: depression
o Most of the time the neurotransmitters are within the body but they cannot cross
the BBB (only precursors can)
Synaptic plasticity: basis of learning processes because a certain pathway is stimulated every
time and the synapses change a bit since they are stimulated so much (more receptors)
o If you do not challenge and stimulate your brain the synapses will degenerate
Neurotransmitter release: through the axon towards the synapse and when there is membrane
depolarisation it results in the influx of calcium (signals to the vesicles with neurotransmitters) which
leads to docking of the vesicles after which it opens up to the synaptic cleft
The released neurotransmitters bind on the postsynaptic cell to a receptor, if enough
neurotransmitter binds then there is again an influx of calcium and the action potential can
be proceeded to cell body of the other neuron
In the synaptic cleft, the neurotransmitters are not degraded directly but are taken up in the
presynaptic
Endocannabinoids: can be instantly formed from the cell membrane, involved in addiction and food
preferences, relatively new field
Brain tissue: all intertwine, much different neurons and glia cells are connected to each other
Grey matter: outside of the brain, lot of neurons cell bodies
o Different compositions of the areas, such as primary sensory (I, II, III), association
(quite even) and primary motor cortex (V and VI)
, White matter: inside of the brain, lot of axons covered with myelin (fatty acid which is white)
Blood-Brain-Barrier: bouncer of the brain, tight system around the capillaries (blood vessels) and only
allowing certain molecules with a transporter or a lipid/gas to actively get transported to enter into
the brain high electrical charge slows down the diffusion across membranes, neuroactive
compounds are highly restricted (e.g. glutamate, adrenalin, dopamine)
Lipids: involved in neuronal membranes (e.g. phospholipid bilayer, membrane fluidity,
synaptic plasticity, vesicle formation), myelin (e.g. sphingolipids which is a major compound),
endocannabinoids (e.g. precursor arachidonic acid)
Glucose: cannot cross the BBB but the brain is highly demanded on energy and is produced
by mitochondria (oxygen-dependent metabolism, making use of ATP) alternative sources
are lactate, ketones, medium fatty acids and acetate
o Has to be actively transported over the BBB by entering via de intestine into the
blood where it reaches the brain eventually where glucose transporter I transports it
into the brain tissue for astrocytes (glucose I transporter), neurons (glucose III
transporter with higher transport rate) and oligodendrocytes (glucose I transporter)
Astrocytes: store glycogen when low glucose levels and can be transformed
into lactate that can serve energy to brain cells
o Low glucose levels: could cause neurons or other brain cells to degenerate sensed
by the AgRP and POMP in the hypothalamus which regulate neuro-endocrinal signals
(hormones) towards the bloodstream which causes the feeling of hunger or via the
vagal nerve
Glucose is mainly metabolised by the mitochondria into ATP where ROS is produced as side effect,
but the brain is vulnerable to this ROS (high lipid content)
Low amounts of ROS: essential in neuronal development and function
Normal conditions: ROS production is neutralised by the antioxidant system
Oxidative stress: ROS production exceeds capacity of antioxidant response system, extensive
protein oxidation and lipid peroxidation occurs, causing oxidative damage, cellular
degeneration and even functional decline
Neuroinflammation: initiated by a variety of cues, e.g. infection, traumatic brain injury, toxic
metabolites or oxidative stress
Chronic inflammation (brain injury, ageing, viruses, toxic metabolites): microglia’s and
astrocytes come into action (morphologically change) and try to save the brain from damage,
can lead to neurological disorders
Blood flow: the arteries which turn into capillaries (branch really small that merge into each other)
Towards the brain: two big arteries
o Vertebral artery: emerges into the basilar artery from which smaller arteries emerge
and ends in a kind of circular artery (circle of Willis) that turn into the posterior
cerebral artery, the middle cerebral artery and the anterior cerebral artery
Posterior: supplies the posterior (back) part of the brain with blood
Middle: supplies the middle part of the brain and the part around the ears
with blood
Anterior: supplies the middle and medial part of the brain with blood
Circle of Willis: functions as a plan B when one part is not working anymore
o Internal carotid artery: heart beat you feel in your neck,
From the brain
Blood flow: the venes which are formed from capillaries
Interior cerebral veins: above the ears
, Straight sinus: at the back of the head
Superior sagittal sinus: in the middle of the head between the two brain halves
Upwards pressure: mainly produced with the cerebrospinal fluid is the inner layer within the
ventricles (lateral, third, cerebral aqueduct, fourth)
Vasoconstriction: narrowing of the blood vessels resulting from contraction of the muscular wall of
the vessels, in particular the large arteries and small arterioles leading to a reduced cerebral blood
flow and sympathetic and parasympathetic nervous system
Caused by an increased concentration of calcium ions in vascular smooth muscle cells and
can be induced by oxygen, caffeine, sodium, amphetamines, antihistamines and anaesthetics
Blood flow decreases
Vasodilation: widening of the blood vessels, relaxation of smooth muscle cells within the vessel walls,
in particular in the large veins, large arteries and smaller arterioles leading to an increased blood flow
Caused by a need for oxygen and can be induced by NO, NO induces, ethanol, capsaicin,
papaverine and oestrogen
Frontal: from the front
Lateral: from the side
Dorsal: from the top
Ventral: from the bottom
Medial: from the middle after cutting it open
Basal ganglia: term for several brain areas nucleus accumbens, globus pallidus, subthalamic
nucleus, substantia nigra, putamen and caudate nucleus
Involved in the (eye) movements, procedural/habit learning, decision making, motivation and
emotion
Disorders: addiction, Huntington’s disease, depression, obsessive-compulsive disorder,
Parkinson’s disease, schizophrenia
o Parkinson’s disease: especially the substantia nigra is important because certain
neurons (dopamine neurons) degenerate over there
Limbic system: term for several brain areas cingulate gyrus, epithalamus, dentate gyrus,
amygdala, hippocampus, entorhinal cortex, hypothalamus
Involved in emotion, memory, reward/pleasure, olfaction and autonomic processes (e.g.
energy intake and sleep)
Disorders: addiction, depression, aggression, Alzheimer’s disease, ADHD, autism, PTSS
Amygdala: olive-like nucleus, important emotion centre, closely related to the hippocampus
changes can lead to depression, aggression or PTSS (connectivity between brain areas are changed)
Hippocampus: involved in the formation of short spatial memory (e.g. learning new words for a few
days) and is then transferred to the neocortex (long-term memory) changes can lead to dementia
where the communication between the hippocampus and neocortex is disturbed
Hypothalamus: involved in autonomic processes (e.g. sleep, energy homeostasis, thermoregulation,
heart rate), sexually dimorphisms (e.g. odour, oestrogens) and the link between nervous and
endocrine system (e.g. neuroendocrine function, pituitary gland)
HPA-axis (stress), HPG-axis (puberty)
Energy homeostasis: NPY/Agrp increases appetite, POMC stimulates satiety
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