Lecture 4- CNS, its neurotransmitters and BBB Flashcards
What are the 2 different types of neurons from the CNS
Afferent (sensory)- stimulated when signal detected by sensory receptors
Efferent- Autonomic and somatic motor neurons
What are the 2 types of autonomic neurons and what are their roles?
Sympathetic and parasympathetic
control- smooth and cardiac muscle
exocrine glands/ cells, some endocrine g/c and some adipose tissue
What do somatic motor neurons control?
Skeletal muscle
What are the components of the brainstem?
Midbrains, pons and MO
Conduit for asc/ desc tracts of spinal cord, contains important reflex centres and important nuclei of CN III > XII
What is contained in the midbrain?
Nuclie of CN III (extrinsic eye muscles) + CN IV (superior oblique)- eye movement
Edinger- westphal nucleus - pupillary diameter, accomodation of lens + eye convergences
Eye, head and neck reflex responses to visual/ auditory signals
What is contained in the pons
Motor nucleus for CN V- muscles of mastication
Nucleus CN VI - eye movement, lateral rectus muscle
Sensory nucleus CNV- sensory from face, scalp, nose+ mouth
CN VIII- hearing and equilibrium, nuclei involved in respiration
What is contained in the MO
Motor N for CN XI- neck muscles Motor N for CN XII- tongue muscles Nuclei involved in resp- CN X Control of BP- CN X and CNIX HR and digestion - CN X
What are the 3 structures contained in the diencephalon
Thalamus- sensory switchboard
Hypothalamus- controls homeostatic, autonomic + endocrine function
Epithalamus- Pineal body- melatonin and circadian rhythm
Habenular nucleus regulates CNS NT (dopamine/ serotonin)- addiction and motivation
What is the role of the cerebellum
Coordinator/predicator of moement- modulates ongiong movement patterns
Integrates info on proprioception, muscle tone, head position in space/ visual and auditory info with info. from cortex
What are the 4 lobes of the cerebrum?
Frontal
Parietal
Occipital
Temporal
Frontal lobe
Largest lobe, precentral gyrus where primary motor areas found
Essential for regulating and initiating vol. motor behaviour
Expressive/ motor aspects of language processed on lateral surface in Broca’s motor speech area
Prefrontal lobe
Extensive connections w/ P, O and T lobes via fasciculi- sensory processing and memory
Monintors behaviours/ controls higher processes (judgement)
Enotion, motivation, personality, initiative, judgement, concentration and social inhibitions
Parietal lobe
Somatosensory regulation
Postcentral gyrus where primary SS area housed
Initial cortical processing/ perception of pain, temperature and proprioception
Wernicke’s area- receptive/ sensory aspects of language
Spatial orientation and perception
Occipital lobe
Processing visual information- these areas surround/ cover lateral surface of lobe
Separated from P lobes by parieto-occipital sulcus
Separated from temporal by calcarine sulcus
Temporal lobe
Auditory information processing- superior temporal gyrus where ability/ interpretation of hearing processed
Lateral surface functions for language perception
Ant. medial areas important in learning memory and emotion
Broca’s area
Inf. frontal gyrus- generation of language, lesion leads to Broca’s aphasia
- difficulty generating written/ spoken language
- little difficulty with language comprehension
Wernicke’s area- superior temporal gyrus
Comprehensino of language- lesion > Wernicke’s aphasia
Difficulty understanding written/ spoken language
Person can generate speech but language meaningless
Basal nuclei/ ganglia
Located under cortical layer- group of interconnecting nuclei within forebrain, diencephalon and midbrain
Include caudate nucleus, putamen, globus pallidus, subthalamic nucleus + substantia nigra
Critical role in initiation/ control of voluntary movement
Limbic system
IC structures that play role in drive related and emotional behaviours
Play role in memory/ learning
Amygdala and hippocampus in limbic system
Hippocampus
Neurogenesis in dentate gyrus of hippocampus- play role in new memories and potential modulation of stress/ depressive symptoms
Lesions affect long term memories- conversion of recent > long memory (anteretrograde amnesia)
Amygdala
Strong emotions, emotional memory and learning and drive related behaviours, processing of emotions related to these
Emotional learning/ behaviour, fear + conditioning + reward, interpretation of emotional behaviours
Common CNS neurotransmitters
Glutamate- most common excitatory NT
Ach- cholinergic neurons release it in forebrain
Dopamine- movement, emoition, motivation and reward- excitatory (D1) and inhibitory (D2)
Noradrenaline- wakefulness and attention: adrenaline acts on same, lower conc
Histamine- wakefulness
Serotonin- E/I effect- mood, emotion, sleep and several homeostatic pathways
Blood- brain barrier
Permeability inversely related to molecule size of molecule, directly related to lipid solubility as it is a continuous lipid bilayer that isolates CNS from blood
What separates the lumen of blood capillary and the extracellular space?
Endothelial cells in cap. wall, continuous BM surrounding the capillary outside the endo wall, foot processes of astrocytes adhere to CW outer surface and tight junctions around the ECW
Where is the BBB absent?
Postrema in floor of 4th ventricle and hypothalamus
Capillary epithelium contains fenestrations, and neuronal receptors can sample chemical content of plasma
