Flashcards in Neuro Deck (172)
Describe the meningeal layers
-From superficial to deep
-Dura mater -> periosteal layer adheres to skull, meningeal layer adheres to periosteal layer except at dural venous sinuses
-Arachnoid mater -> adhered loosely to dura mater. Has sub arachnoid space below
-Pia mater -> closely adhered to gyri and sulci
Describe the ventricular system of the brain
-Two lateral ventricles joined to third ventricle through ventricular foramen, joined to forth ventricle through cerebral aquaduct, all lined by ependymal cells
-Houses choroid plexus which produces CSF
-Drains from 4th ventricle into central canal and subarachnoid space -> arachnoid granulations into dural venous sinuses
List the major functions of the frontal lobe
-Houses pre-central gyrus (primary motor cortex)
-Brocas area for expressing speech
-Behaviour and personality
List the major functions of the parietal lobe
-Houses post-central gyrus (primary sensory cortex)
-Spacial and body awareness
List the major functions of the temporal lobe
-Wernickes area for understanding and processing speech
List the major functions of the occipital lobe
List the major functions of the cerebellum
-Planning and coordination
-Balance and proprioception
Briefly describe the different types of glial cells
-Astrocytes -> star-shaped cells which support the bbb, provide nutrients and maintain ECF
-Oligodendrocytes -> Myelinate multiple CNS axons
-Ependymal cells -> Line the ventricular system and central canal -> circulate CSF
-Microglia -> immune cells of cns (phagocytes)
Describe the diseases produced upon failure of closure of the neural tube
i) ancephaly -> incompatible with life
ii)Spina Bifida -> most commonly lumbosacral. SB meningocoele is when there are when spinal tissue is covered in meninges. It produced mild symptoms. SB myelomeningocoele is when neurological tissue is exposed, produces severe symptoms. SB oculta is loss of spinous processes, often produces no symptoms
-Symptoms include hydrocephalus, poor ability to walk, incontinence
What is rachishisis?
-Failure of the neural tube fold to elevate out of the plane causing ancephaly
How are neural tube defects diagnosed? How can they be prevented?
-Raised maternal serum a-fetoprotein
-Preconceptual and 1st trimester folic acid
Why does the corda equina develop?
-Vertebral column grows faster then SC meaning spinal roots must elongate to exit at the corresponding intervertebral foramen
After the 3 primordia of the brain develop, how do they progress and into what areas of the brain do they develop?
-Prosencephalon -> telencephalon (cerebral hemispheres) and diencephalon (thalamas)
-Mesencephalon -> midbrain
-Rhombencephalon -> melencephalon (pons/cerebellum) and myelencephalon (medulla oblongata)
-2 flexures develop due to lack of space ->cervical between spinal cord and hind brain and cephalic between midbrain and cerebrum
Give a communicating and non-communicating cause of hydrocephalus
-Non-communicating = cerebral aquaduct sternosis/arnold-chiari
-Communicating = arachnoiditis/meningitis
Name 3 diseases involved in failure of neural crest cells
-Hirchsprungs (aganglionic megacolon)
Describe in detail how the astrocytes provide nutrients for neurones, remove neurotransmitters and maintain the ionic environment
-Use a glucose-lactate shunt -> take up glucose and store it as glycogen. When brain needs it converts glycogen -> lactate by anaerobic respiration. Lactate can be used in brain in times of need
-Use reuptake transporters to reuptake neurotransmitters such as glutamate into cells to keep EC concentrations low. Once uptaken glutamate recycled to glutamine
-Maintain ionic environment as neuronal activity raises [k]ec which is taken up by astrocytes to prevent inappropriate electrical activity of neurones
What makes up the bbb? What is the function of the bbb?
-Brain capillary endothelia joined by tight junctions, pericyte, foot processes of astrocytes
-Limits diffusion of blood product into csf to support the environment for neurones
Describe the different types of neurotransmitters (class and excitatory or inhibitory)
-Amino acid -> glutamate (excitatory), glycine (brainstem/SC) and GABA (inhibitory)
-Biogenic amines -> ach (mainly excitatory), dopamine, NA, serotonin
What types of receptor does glutamate act on? Which receptor is responsible for fast depolarisations? Which receptor is blocked by Mg? What is the consequence of this? What cortical function are glutamate receptors involved in?
-NMDA and AMPA
-AMPA is fast depolarising
-NMDA is blocked by Mg and therefore requires lots of stimulation in order to activate it
-Learning and memory
What type of ion channels are linked to GABA and glycine receptors? What happens when these neurotransmitters bind?
-Opens Cl- channels and Cl- enters the cell leading to hyperpolarisation -> decreased AP firing thus post synaptic potential inhibited
Which receptors do barbituates/benzos bind to? How do they modify this receptor? What outcome do they produce via this mechanism? When are they used? What is the risk of using them?
-Increase the receptors sensitivity to GABA
-Anxiolytic and sedation via increasing inhibitory response of GABA binding
-Anxiety, insomnia, status epilepticus
-Dependance and fatal overdose
In which processes is Ach commonly found to be the neurotransmitter?
-Arousal of CNS
-Learning and memory
Why are AchE inhibitors sometimes used in Alzheimer's?
-Degeneration of nucleus basalis which houses ach neurones. AchE inhibitors potentiate action of remaining Ach neurones
What 4 pathways is dopamine involved in? What are 2 common diseases which involve dopamine dysfunction, and in what way is dopamine altered?
-Nigrostriatal (Motor control)
-Mesocortical and mesolimbic (mood, arousal and emotion)
-Parkinsons (decreased) and Schizophrenia (increased)
What is the function of NA as a transmitter within the CNS?
-Behaviour arousal and mood
What are the functions of serotonin within the CNS?
-Sleep and mood
What is the difference between somatic and visceral sensation?
-Visceral pain/sensation is diffuse and hard to localise and only detects stretch, ischaemia, and inflammation
-Somatic sensation/pain is sharp and easy to localise and detects all types of sensation including 2-point discrimination and temperature
What are modalities and qualities when referring to sensation? What determines the modality/quality?
-Modality is the subtype of sensation eg temperature/pressure etc
-Quality is a subtype within the modality eg hot/cold
-Determined by the type of receptor activated and how it is activated
How do APs relate to the intensity of sensory stimuli?
-The more intense the sensory stimuli, the higher the frequency/duration of APs due to a greater change in mp