Central Nervous System Flashcards
What is the anatomical planes of the brain?
The brain can be viewed in three ways
What are the three ways the brain can be viewed?
Coronal/Frontal Plane
(Para)sagittal/(para)median Plane
Transverse, horizontal or axial plane
How is the nervous system organised on an anatomical level?
- Central Nervous System
- Peripheral Nervous System
What does the central nervous system contain?
Brain and Spinal cord
What does the peripheral nervous system?
Cranial nerves and Spinal nervers
What does the functional level of the nervous system contain?
- Somatic Nervous System
- Autonomic Nervous System
What does the somatic nervous system control?
Control of movement
External environment
What doe the automatic nervous system control?
Internal environment
Homeostasis
What are the subunits of the automatic nervous system?
Sympathetic
Parasympathetic
Enteric
What are the two types of cells?
- Neurons
- Glia
What is the structure of a neurone?
Dendrites
Soma (Cell body)
Axons
What are the synapse involved in neurones?
Transmission of information
Involves neurotransmitter
Pre synaptic neurone to post synaptic neurone
What is the function neurone?
Afferent neuron
Interneurons
Efferent Neurons
What is an afferent neurone?
Receive information from sensory organs and then transmit to CNS
What is the interneurone?
Acts as an intermediary in passing signals between two other neurones
What is an efferent neurone?
Send impulses from the central nervous system to your limbs and organs
What is the characteristics of a glia?
- Outnumber neurones by 2-10 times
- Haves processes, but no dendrites or axons
What is the function of a glia?
- Not directly involved in information processing
- Structural matriculates, homeostasis, protection
What are the different types of glia?
- Microglia
- Macroglia
- Ependyman cells
What does the macroglia include?
- Astrocytes
- Oligodendrocytes
What are different parts of a spinal cord?
- Spinal nervers
- Grey matter
- White matter
What is the spinal nerve made out of?
- Dorsal root
- Ventral root
What does the dorsal root contain?
- Afferent neurons
- Somas in dorsal root ganglion
What does the ventral root contain?
- Motor neurons
- Somas within spinal coord
What does the grey matter include?
- Dorsal horns
- Ventral horns
What is the dorsal horns?
- Afferent neurones from sensory receptors
- Origin of ascending pathways to the brain
What is the ventral horns?
- Motor neurones
- Innervate skeletal muscle
What does the white matter include?
- Ascending tract
- Descending tract
Where does the information involved in the ascending tract of white matter go?
The brain
What does the ascending tract of the white matter include?
- Dorsal columns
- Spinothalamic
- Spinocerebellar
What is the dorsal columns?
Fine touch and proprioception
What is the spinothalamic?
Pain, coarse touch, temperature and pressure
What is the spinocerebellar?
Receptors in joints and muscles
What does the descending tract of the white matter include?
Lateral corticospinal tract?
What is the lateral corticospinal tract?
Voluntary movement
In the spinal nerve is the sensory info (involved with the dorsal root) joined to the motor info (involved with the ventral root)?
No they are separated
What is more excitable a neurone or glia?
Neurone
When is a microglia cell activated?
When a pathogen is present
What is the ependymal cell?
Epthial cells lining the ventricle
When are astrocytes (involved with the macroglia cell) activated?
In homeostasis and forms blood brain barrier (selectively allows chemicals into the brain)
What are the components of the brainstem?
- Medulla oblongata
- Pons
- Midbrain
What is the does the brainstem connect?
The spinal cord to the brain
What is the vital function of the brainstem?
Control breathing and level of arousal
What does the ascending fibre of the brainstem function?
Sensory
What does the descending fibre of the brainstem function?
Motor
What is the cerebellum structure?
- Cerebellar cortex
- White matter
- Peduncles
What are the components of the peduncles?
- Superior (Midbrain)
- Middle (Pons)
- Inferior (Medulla)
What is the function of the cerebellum?
- Movement coordination
- Muscle tone
- Equilibrium
- Posture
What are the two components that make up the diencephalon?
- Hypothalamus
- Thalamus
What is the function of the hypothalamus?
- Autonomic (homeostasis)
- Limbic (emotions)
- Neuroendocrine (pituitary gland)
What does the hypothalamus contain?
Several nuclei
What does the thalamus contain?
Several nuclei
What is the thalamus a gateway to?
The cortex
What part of the diencephalon get input from most areas of the CNS?
Thalamus
What is the function of the thalamus?
- Sensory
- Motor
- Cognitive
What does the cerebral hemisphere made out of?
- Grey matter
- Whute matter
What is the largest part of the brain?
Cerebral hemisphere
What makes up the grey matter in the cerebral hemisphere?
- Cerebral cortex
- Basal ganglia
What makes up the white matter in the cerebral hemisphere?
- Corpus callous
- Corona radiata
- Internal capsule
What is the basal ganglia made up of in the cerebral hemisphere?
- Caudate
- Putamen
- Globus pallidus
What does the basal ganglia do?
Control of movement, posture and muscle tone
Finish the sentence:
The cerebral cortex is highly…
convoluted
What are the different types of convolutes that make up the cerebral cortex?
- Gyrus
- Sulcus
- Fissure
Describe the gyrus in the cerebral cortex:
Ridge of cortex
Describe the sulcus. in the cerebral cortex:
Shallow groove
Describe the fissure in the cerebral cortex:
Deep sulcus
What are the different lops in the cerebral hemisphere?
- Frontal
- Parietal
- Temporal
- Occipital
- Insula
What are each lobe divided into?
Different functional areas
What are the primary areas of the cerebral hemisphere?
- Motor cortex
- Somatosesonsory cortex
- Auditory cortex
- Visual cortex
What does the motor cortex control?
Voluntary movement
What does the somatosensory cortex control?
Somatosensation
What does the auditory cortex control?
Hearing
What does the visual cortex control?
Seeing
What are the secondary areas of the cerebral hemisphere?
- Broca’s area
- Wernicke’s area
What is the Broca’s area?
Language expression
What is the Wernicke’s area?
Language comprehension
What are the higher order areas of the cerebral hemispheres?
- Multimodel Integration
- Attention
- Recognition
- Decision making
- Personality
What is the function of the frontal lobe?
Judgement, motor planning and personality
What is the function of the visual association?
Object recognition
What is the function of the posterior parietal?
Spatial awareness
What makes up the white matter of the cerebral hemisphere?
Corona radiate and internal capsule
What does the corona radiata connect the cerebral cortex with?
- Basal ganglia
- Thalamus
- Spinal cord
What is the cranial nerves?
Majority carry sensorimotor information
Where can you find the cranial nerves?
Innervate the head and neck
What is the cranial nerves made up off?
Twelve pairs with point of attachments
How do we identify the twelve pairs of cranial nerves?
- Individual names
- Roman number
Finish the sentence:
The cranial nerves is a complex system of linked chambers surrounding…
deep brain structures
What is the I cranial nerves?
Olfactory nerve
What is the II cranial nerve?
Optic nerve
What is the III cranial nerve?
Oculomotor nerve
What is the IV cranial nerve?
Trochlear nerve
What is the V cranial nerve?
Trigeminal nerve
What is the VI cranial nerve?
Abducent nerve
What is the X cranial nerve?
Vagus nerve
What is the XI cranial nerve?
Spinal accessory nerve
What is the XII cranial nerve?
Hypoglossal nerve
What is the IX cranial nerve?
Glossopharyngeal nerve
What is the VIII cranial nerve?
Vestibulacochlear nerve
What is the VII cranial nerve?
Facial nerve
What is the ventricular system?
A complex system of linked chambers surrounding deep brain structures
What is the choroid plexus part of?
The ventricular system
What is the choroid plexus?
- Produces the cerebrospinal fluid
- Invagination of the pia matter
What is meant by invagination?
A cavity or pouch formed by being turned inside out or folded back
Where is the choroid plexus located?
In the lateral, third and fourth ventricles
What does the choroid plexus appear as?
Spongy-like apperance
What is continuously secreted and reabsorbed in the ventricular system?
The cerebrospinal fluid
What is the function of the cerebrospinal fluid?
Homeostasis and protection
What is the circulation pathway of the cerebrospinal fluid?
Lateral ventricle to the third ventricle to the fourth ventricle to the subarachnoid space
What reabsorbed the cerebrospinal fluid?
The arachnoid villi
What covers the brain and the spinal cord?
Meninges
What is meninges function?
Protection
How many layers of membranes does meninges have?
Three
What are the three layers of membranes of the meninges?
- Dura mater
- Arachnoid mater
- Pia mater
Describe the dura mater of meninges:
- Fibrous
- Loosely attached to the CNS
Describe the arachnoid mate:
- Collagenous
- Blood vessels and CSF
Describe the pia mater:
- Very thin
- Firmly attached to the surface of the CNS
What is the Falx cerebri of the meninges?
Sagittal plane between the two cerebral hemispheres
What is the tentorium cerebelli?
Horizontal plane between the occipital lobes and cerebellum
What is the flax cerebri above?
The corpus callosum
What is the tentorium cerebelli continuous with?
Continuous with the falx cerebri
What is the dural venous sinuses?
- In the falx cerebri and tentorium cerebelli
- Venous drainage of the brain
What is a synapse?
A specialised junction where a neurone contacts and communicates with another neurone or cell (muscle or gland)
What are the types of synapse?
- Electrical
- Chemical
What is an electrical synapse?
Located at specialised membrane sites called gap junctions
What is gap junction made out of?
- 2 connexons
- 6 connexins
What is a electrical synapse a direct transfer of?
Ionic currents between cells
Which synapse is bidirectional?
Electrical synapse
Which is the faster synapse?
Electrical synapse
What is a chemical synapse?
Chemical messenger via neurotransmitters
Which synapse is unidirectional?
Chemical synapse
Which is the slower synapse?
Electrical synapse
What is the structure of a chemical synapse?
- Presynaptic terminal
- Synaptic cleft
- Postsynaptic terminal
What is the presynaptic terminal?
- Contains synaptic vesicles
- Active zone
What is the synaptic cleft?
- Made of matrix of proteins
- Adhesion
What is the postsynaptic terminal?
- Postsynaptic density
- Receptors
What is a neurotransmitter?
A chemical messenger meeting four criteria
What are the four criteria that must be meant to be a neurotransmitter?
- Synthesised in presynaptic neurone
- Exert an action on postsynaptic cell
- Exogenous administration mimics the endogenous effects
- Specific mechanism to remove it from the synaptic cleft
What are the three types of neurotransmitters?
- Amino acids
- Amines
- Peptides
How are peptide neurotransmitters synthesised?
- Rough ER to Golgi apparatus which activated peptide transmitter
- Producing secretary granules
Where are all neurotransmitters stored?
The presynaptic terminal
How are the amines and amino acids synthesised?
Precursor molecule synthesis by synthetic enzyme forming a neurotransmitter molecule.
Then transport protein forms a synaptic vesicle around neurotransmitter
What is a neurotransmitter released?
- Import of neurotransmitter = presynaptic terminal is polarised causing voltage-gated ions to open
- Movement to active site = synaptic vesicles move
- Docking at plasm zone = vesicles join presynaptic membrane
- Ca^2+ triggers exocytosis = fusing membrane of vesicle and presynaptic membrane
- Neurotransmitters are realised in to synaptic cleft
- Endocytosis via Cathrin-coated vesicles = close membrane and reload with neurotransmitters by fluctuation of H^+
How do neurotransmitter effect postsynaptic terminal?
Bind to specific receptors which are transmembrane proteins embedded in postsynaptic density where a conformation change occurs when activated by neurotransmitters
What are the two types of receptors at the postsynaptic terminal?
- Ligand-gated ion channels
- G protein-coupled receptors
What is the structure of a ligand-gated ion channel?
- Membrane-spanning proteins
- 4/5 subunits = pore
- Ion selective
What happens to a ligand-gated ion channel when activated?
- ligand bind to active site
- Conformational cang
- Pore open
What does ligand-gated channels effect?
Excitatory/inhibitory (depending on ion)
Fast
What are the components of s GPCR?
- Receptor (transmembrane protein)
- G-protein (intracellular)
- Effector (ion channel or enzyme)
What happens when GPCRs are activated?
Ligand bind to active site
Conformational change of G-protein
Activation of effector
What are the effects of GPCRs?
Slower but lasts longer
What must happen to a neurotransmitter to allow another run of synaptic neurotransmission?
Removal of neurotransmitter from synaptic cleft
What are two examples of amino acid neurotransmitters?
- Glutamate
- GABA
What are the receptors for glutamate?
AMPA, Kainate and NMDA
What are the receptors for GABA?
GABAa and GABAb
Is the glutamate neurotransmitter must abundant for excitatory or inhibitory?
Excitatory
How is glutamate synthesised?
From glutamine by the enzyme glutaminase
What is the action of glutamate terminated?
- Reuptake by excitatory amino acid transporters (EAAT)
- Loaded into synaptic vesicles (antiproton transporters)
What are the two ionotropic glutamate receptors?
AMPA
NMDA
Describe the AMPA receptor to glutamate:
- Ligand-gated
- Permeable to Na+ and K+
- Fast excitatory synaptic transmission
Describe the NMDA receptor to glutamate:
- Ligand-gated and voltage-gated
- Permeable to Na+, K+ and Ca2+
- Slow excitatory synaptic potential
What are the three metabotropic glutamate receptors?
- Group I
- Group II
- Group III
What metabotropic glutamate receptor increase synaptic transmission and excitability?
Group I
What metabotropic glutamate receptor decreases synaptic transmission and excitability?
Group II and group III
What does GABA stand for?
γ-Aminobutyric Acid
Is the GABA neurotransmitter the main neurotransmitter for for excitatory or inhibitory?
Inhibitory
How is GABA synthesised?
From glutamate by glutamic acid descarboxylase (GAD)
How is GABA terminated of action?
- Reuptake by Na+ - dependent transporters
- Metabolised by the enzyme GABA transaminase in astrocytes
Which GABA receptor is ionotropic?
GABAa
Which GABA receptor is metabotropic?
GABAb
Describe GABAa receptors:
- GABA-gated Cl- channels
- α-β-α-β-γ subunits
- Binding sites between α-β subunits
- Located at postsynaptic
- Mediate fast and tonic inhibition
Describe GABAb receptors:
- GPCR
- Inhibit violate-gated Ca2+ channels
- Opens K+ channels
- Inhibit the adenylyl cyclase pathway
- Dimer: two seven transmembrane subunits
What are the two dimes of GABAb?
- B1: binding site for GABA
- B2: interacts with the G protein
Give 3 examples of amine neurotransmitters:
- Acetylcholine
- Serotonin
- Catecholamines
What are the three catecholamines?
- Dopamine
- Norepinephrine
- Epinephrine
What is the receptor for acetylcholine?
Muscarinic and Nicotinic
What is the receptor for serotonin?
5TH 1-7
What is the receptor for dopamine?
D1 and D2
What are the receptors for norepinephrine?
α & β
What are the receptors for epinephrine?
α & β
How is acetylcholine synthesised?
By chlorine acetyltransferase (ChAT) from choline and acetyl CoA
How is acetylcholine degraded?
By acetylcholinesterase (AChe) in the synaptic cleft to choline and acetic acid
How is choline taken up in the presynaptic cell?
By choline co-transporters with Na+
Which acetylcholine receptor is ionotropic?
Nicotinic
What acetylcholine receptor is metabotropic?
Muscarinic
Describe nicotinic receptors:
Ligand-gated ionotropic receptors
Permeable to Na+, K+ and Ca2+
Excitatory effect
Describe muscarinic receptors:
GPCRS
Five types: M1-M5
Nervous system: M1, M4 and M5
What does M1 and M5 couple to?
Gq
Is the coupling of M1/M5 to Gq excitatory or inhibitory?
Excitatory
What does M4 couple to?
Gi
Is the coupling of M4 to Gi excitatory or inhibitory?
Inhibitory
What does acetylcholine act on?
- Basal forebrain
- Brainstem
What is acetylcholine involved in?
- Attention
- Arousal
- Reward
- Learning and memory
What is the actual name of serotonin?
5-hydroxytryptamine (5-HT)
How is serotonin synthesised?
From amino acid tryptophan by a sequence of enzymatic reactions
What enzyme synthesised 5 HTP from tryptophan?
Tryptophan hydroxylase
What enzyme synthesised serotonin from 5 HTP?
5 HTP decarboxylase
How is serotonin terminated?
- Reuptake from synaptic led by membrane transporters
- Reloaded in to synaptic vesicle or degraded by MAO
What type of receptor is 5TH3?
Ionotropic - ligand gated Ca2+ channel
What type of receptors are 5TH 1-7 excluding 5TH 3?
Metabotropic
Is the receptor 5-TH cause an inhibitory or excitatory effect on presynaptic/postsynaptic neurones?
Both
Where are serotonergic neurons located?
Raphe Nucleus of the brainstem
Where does serotonin effect?
Cortex
Hypothalamus
Spinal cord
What is serotonin included in?
- Sleep/wake cycles
- Mood/emotion
- Feeding behaviour
- Thermoregulation
- Pain
Where are catecholamines neurotransmitters derived from?
Amino acid tryosine
How are catecholamines terminated?
- Reuptake from synaptic cleft by membrane transporters
- Reloaded into synaptic vesicles or degraded by MAO
What is catecholamines involved in?
- Motor control
- Mood
- Attention
- Arousal
How do the D1 family receptors of dopamine act?
Gs (excitatory)
Activate ionic channels (Na+, K+ and Ca2+)
What are the receptors in the D1 family?
D1, D5
How do the D2 family receptors of dopamine act?
Gi (Inhibitory)
Activate K+ channels
Inhibit Ca+2 channels
What are are the receptors in the D2 family?
D2, D3 and D4
What are the functions of dopamine?
- Motor (nigrostriatal pathway)
- Behaviour: mesocortical and mesolimbicpathway
- Endocrine: tuberohpophyseal pathway
What are the other names for norepinephrine and epinephrine?
Noradrenaline and adrenaline
How are the action of norepinephrine and epinephrine mediated?
By GPCRs = α1, α2, β1 and β2
How are norepinephrine and epinephrine synthesised?
By neurons of brainstem
What are norepinephrine and epinephrine important in?
- Control of wakefulness and alertness
- Control of mood
- Stress reaction
Give 2 examples of peptide neurotransmitter:
- Insulin
- Somatostatins
What do peptide neurotransmitter activity depend on?
Amino acid sequence and length
How are peptide neurotransmitters synthesised?
Pre-propeptide to propeptide to peptide by proteases
How are peptide neurotransmitters degraded?
By peptidase into inactive amino acids
What can peptide neurotransmitters be released with?
Smaller neurotransmitter
What are the differences between peptide and smaller neurotransmitter?
- Synthesised in the cell body
- Stored in dense-core vesicles (Golgi)
- Exocytosis not limited to active zone and requires non-localised increase of Ca2+ concentration
What are the actions of peptide neurotransmitters?
- Sensory perception
- Emotion
- Pain
- Stress
- Reproduction
- Reward
- Analgesia
- Food intake
What type of receptors are involved in with peptide neurotransmitter?
GPCRs
What are the characteristics of a neuromodulator?
- Mediators
- Produced by neuronal or non-neuronal cells
- Cannot be stored
- Released as convectional neurotransmitter
- Regulate the release of the neurotransmitter release/post
- GPCRs
- Slower response
What are the different types of neuromodulator ?
- Conventional neurotransmitters acting on autoreceptors
- Lipid mediators
- Gaseous mediators
Where can you find auto receptors?
Presynaptic membrane
What are auto receptors sensitive to?
Own neurotransmitters
What type of receptors are auto receptors?
Mainly GPCRs
What type of mechanism are auto receptors?
Self-regulating
What is the endocannabiniod system relating to neuromodulators?
Feedback system to regulate conventional synaptic transmission
Where is the endocannabinoid system synthesised?
By post synaptic cell when every active
What does endocannabinoid system do?
Reduces the opening of presynaptic calcium channels inhibiting neurotransmitter release
What are the two main GPCRs of the endocannabinoid system?
CB1
CB2
What are the two main ligands of the endocannabinoid system?
- Anandamide (AEA)
- 2-Arachydonil glycerol (2-AG)
What type of neuromodulator is the endocannabinoid system?
Lipid mediator