central nervous system Flashcards
main lobes of the brain
frontal, parietal, temporal and occipital
end nearest the brain stem
caudal or dorsal
end nearest the frontal lobe
rostral or ventral
function of the frontal lobe
located at the front of the brain nd associated wit reasoning, motor skills and high level cognition and expressive language
when the frontal lobe is damaged
lead to changes in sexual habits, socialisation and increased risk taking
function of parietal lobe
between frontal and occipital and on top of temporal
- associated with processing tactile sensory info such as pressure touch and pain
when the parietal lobe is damaged
problems with verbal memory; an impaired ability to control eye gaze and problems with languag
occipital function
located at the back ( caudal) .
associated with interpreting visual stimuli and info. The primary visual cortex located in this lobe.
when the occipital lobe is damaged
visual problems, such as recognising objects, an inability to identify colours and trouble recognising words
temporal function
location of primary AVAITORY CORTEX which is important for interpreting sounds and the language we hear. Hippocampus is also located here and is associated with the formation of memories
cerebellum
coordination and balance e.g. walking and posture
medulla oblongata
helps regulate breathing, heart rate and blood vessel function, digesting, sneezing and swallowing
hypothalamus
controls the release of the 8 major hormones
- controls body temp
- controls food and water intake
- sexual behaviour and reproduction
pituitary
- endocronic- releases hormones that regulate the function of other endocrine glands
- anterior and posterior
pons
control of breathing and communication b/w diff parts of the brain and sensations such as hearing, taste and balance
basal ganglia
voluntary motor control, procedural learning and eye movement
-also emotional and cognitive function
hippocampus
long term memory
spatial navigation
amygdala
detects fear and prepares for emergency events
7 main regions of CNS
spinal cord, medulla, the pons, cerebellum, midbrain, diencephalon, cerebral hemisphere
parts of the brain responsible for higher functions
e.g. temporal lobe- emotional reaction and understanding language
frontal lobe- decision making
lobes responsible for memories
frontal- (prefrontal cortex)- processes long and short term memories
temporal- integrates senses of smell and sound and vision–> needed form long term memories
what is long term potentiation
LTP is an increase in efficacy of synapses with repetitive stimulation- therefore increasing synaptic transmission. New synapses will form by splitting pre-existing ones. First discovered to occur in the hippocapmus
mechanism of LTP
weak stimulation of the presynaptic neurone will cause the release f the NT Glutamate. The glutamate will bind to both AMPA (inotropic) and NMDA (metabotropic) receptors. However at weak stimulation glutamate will only activate AMPA receptors. This will only cause slight depolarisation. Therefore v.few ions will flow through NMDA channels since they were blocked with Mg2+. If the stimulation is larger than AMDA receptors can depolarise the membrane sufficiently to expel the Mg2+ from the pore. Therefore glutamate will now be able to flow through the NMDA. Ca2+ will also flow through the open NMDA receptor.
synaptic plasticity
the ability of a membrane to change its permeability
what effect does Ca2+ have on the post synaptic men.
acts as a second messenger and activates a signalling cascade.
1) some Ca2+ will bind to calmodulin and this activates several protein kinases including calcium/calmodulin dependent kinases.
2) Ca2+ also facilities the release of NT from presynaptic axon terminal via retrograde signals, such as NO
CAMkinase effects the AMPA receptors in 2 ways
1) phosphorylates AMDA and this increases their conduction to sodium ions
2) CAMK2 promotes the movement of AMPA receptors from intracellular stores into the membrane- therefore more receptors available
result of having more AMPA receptors
the response to a stimulus of a given strength will be stronger than it was before NMDA receptors were activated
two cognition enhancing drugs
adderall and modafinil
all amphetamines work to increase dopaminergic transmission and therefore has a v similar effect on ACh
types of NT in the CNS- 6
ACH peptides amino acids biogenic amines purines gases and liquids
ACH receptors in CNS
nicotinic-inotropic
muscarinic- metabotropic
role of ACH nicotinic receptors
1) presynaptic and pre terminal receptors enhance nt release
2) postsynaptic receptors mediate a small minority of fast excitatory transmission
some have a role in synaptic plasticity
therefore they are important modulators if neuronal excitability.
what causes myelination in CNS neurones
glial cells called oligodendrites
why are not all neurones in the CNS myelinated
sometimes saltatory conduction just isn’t needed due to the neuronal distance being so short
-also some neurones are responsible for dull, long lasting pain- therefore no benefit to having it transmitted quickly
which enzyme synthesises ACH and which breaks it down
acetyl cholinetransferase
acetyl cholinesterase
side effect of cognition enhancing drugs
organ damage seizures addiction psychotic behaviour malnutrition
what is the blood brain barrier
a dynamic interact which separates the brain from the circulatory system and therefore protects the CNS from potentially harmful chemicals
-formed by a highly specialised endothelial cells that line the brain capillaries and transduce signals from the vascular system and the brain
what keep the endothelial cells tight together
tight junctions–> regulated by cytoplasmic proteins–> keeps the integrity of the barrie
role of pericytes in BBB
maintains tight junctions and has contractile properties
role of astrocytes (glial cells)
maintenance of BBB
why is the capillary highly selective
only permeable to molecules like nutrients that won’t damage the brain
allows waste products, hormones or excess NT to leave the brain
few drugs will pass the barrier
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