Lecture 4- CNS, its neurotransmitters and BBB

Question 1

What are the 2 different types of neurons from the CNS

Answer 1

Afferent (sensory)- stimulated when signal detected by sensory receptors
Efferent- Autonomic and somatic motor neurons

Question 2

What are the 2 types of autonomic neurons and what are their roles?

Answer 2

Sympathetic and parasympathetic
control- smooth and cardiac muscle
exocrine glands/ cells, some endocrine g/c and some adipose tissue

Question 3

What do somatic motor neurons control?

Answer 3

Skeletal muscle

Question 4

What are the components of the brainstem?

Answer 4

Midbrains, pons and MO

Conduit for asc/ desc tracts of spinal cord, contains important reflex centres and important nuclei of CN III > XII

Question 5

What is contained in the midbrain?

Answer 5

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

Question 6

What is contained in the pons

Answer 6

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

Question 7

What is contained in the MO

Answer 7

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

Question 8

What are the 3 structures contained in the diencephalon

Answer 8

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

Question 9

What is the role of the cerebellum

Answer 9

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

Question 10

What are the 4 lobes of the cerebrum?

Answer 10

Frontal
Parietal
Occipital
Temporal

Question 11

Frontal lobe

Answer 11

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

Question 12

Prefrontal lobe

Answer 12

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

Question 13

Parietal lobe

Answer 13

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

Question 14

Occipital lobe

Answer 14

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

Question 15

Temporal lobe

Answer 15

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

Question 16

Broca’s area

Answer 16

Inf. frontal gyrus- generation of language, lesion leads to Broca’s aphasia

• difficulty generating written/ spoken language
• little difficulty with language comprehension

Question 17

Wernicke’s area- superior temporal gyrus

Answer 17

Comprehensino of language- lesion > Wernicke’s aphasia
Difficulty understanding written/ spoken language
Person can generate speech but language meaningless

Question 18

Basal nuclei/ ganglia

Answer 18

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

Question 19

Limbic system

Answer 19

IC structures that play role in drive related and emotional behaviours
Play role in memory/ learning
Amygdala and hippocampus in limbic system

Question 20

Hippocampus

Answer 20

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)

Question 21

Amygdala

Answer 21

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

Question 22

Common CNS neurotransmitters

Answer 22

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

Question 23

Blood- brain barrier

Answer 23

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

Question 24

What separates the lumen of blood capillary and the extracellular space?

Answer 24

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

Question 25

Where is the BBB absent?

Answer 25

Postrema in floor of 4th ventricle and hypothalamus

Capillary epithelium contains fenestrations, and neuronal receptors can sample chemical content of plasma