Week 3- Introduction to CNS+cerebral cortex+glial cells

Question 1

what is the components of the CNS?

Answer 1

-BRIAN AND SPNAL CORD

Question 2

what is the brain divided into?

Answer 2

– Brain stem
– Cerebellum
– Forebrain
• Diencephalon
• Cerebrum

Question 3

what component of the brain is connected to the spinal cord?

Answer 3

brain stem

Question 4

what is the brain stem sub divided into?

Answer 4

• medulla oblongata

- midbrain

Question 5

what is the brain stem? what it does?

Answer 5

-known as relay centre
– Information between higher brain and
spinal cord
– Initial processing (neural integration)
-Reflexes involved in balance and posture
- Site of exit for most cranial nerves

Question 6

what is the reticulum formation?

Answer 6

– Network of neurons throughout the brain
stem
– Receives and integrates sensory input
• “filtering” un-necessary information
– Consciousness
– Arousal (wakefulness)
• Reticular activating system

Question 7

what type of function and what happens in the medulla oblongata?

Answer 7

– Involuntary function
• Vital reflex centre (control of
breathing, circulation, digestion eg.
the respiratory control centre)
• Non-vital reflex centre (eg. coughing,
vomiting (chemoreceptor trigger
zone - CTZ))

Question 8

what is found in the midbrain?

Answer 8

– Contains the substantia nigra

Parkinson’s disease

Question 9

what is the cerebellum? where it is, involved?

Answer 9

Attached to the brain stem
• Execution of coordinated voluntary
movement (fine control)
– Integration of information
• Position of the body
• Sensory information from
muscles, joints, skin, eyes, ears,
viscera. Inputs from motor areas
of the cerebrum
• Involved in planning and initiation
of movement
– Inputs to motor areas
• Procedural memory
– co-ordination of sub-conscious motor
tasks
• Balance
• Eye movement

Question 10

what is the diencephalon divided into?

Answer 10

thalamus

hypothalamus

Question 11

what is thalamus? where and function

Answer 11

-above the mid brain
– Relay centre
• Sensory input (all via thalamus:
preliminary processing, filtering,
directing of signals)
– Directing attention
• Motor control

Question 12

what is the function of the hypthalamus?

Answer 12

– Major homeostatic control centre
• Integrates homeostatic input
• Regulation of autonomic nervous
system and endocrine system
• Eg. control of body temperature
– Controls secretion of hormones by the
pituitary gland
– Forms part of limbic system (emotion,
behavioural patterns and memory)
– Role in sleep/wake cycles

Question 13

what is the limbic system? where,

Answer 13

• Interconnecting group of
structures in the forebrain
• Basic emotions (fear, anxiety,
anger, pleasure, satisfaction)
• Neural centres controlling basic
behaviour
– Preparing for attack/defense,
laughing, crying
– Survival - eating, drinking,
sexual behaviour
• Reward pathways
• Motivation
– Punishment pathways
• Olfaction (smell)
• Hippocampus –memory

Question 14

what is the cerebrum? consist of?

Answer 14

• Consists of the cerebral cortex and the basal nuclei (basal
ganglia)

Question 15

what is the basal nuclei?

Answer 15

• Collections of neuronal cell bodies
(nuclei or ganglia). Includes striatum
(caudate nucleus, putamen and
separating structure), globus pallidus.
Also the substantia nigra and the
subthalamic nuclei (in brainstem)

Question 16

what is the function of the basal nuclei?

Answer 16

• Involved in control of movement
(extrapyramidal motor system)
– Modulation of motor activity
• Generally an inhibitory role
– Inhibition of muscle tone
– Purposeful v unwanted movement
– Posture/support (co-ordination of
sustained contractions)

Question 17

what is the cerebral cortex? consist of?

Answer 17

• Two hemispheres
• 80% weight of human brain
• Consist of a shell of grey matter
(cell bodies, dendrites, glia)
covering a mass of white matter
(myelinated axonal tracts)
• Highly convoluted (gyri is the peaks and sulci is the troughs to increase the surcae area) –
proportional to complexity of the
organism

Question 18

what does the cerebral cortex consist?

Answer 18

• Control contralateral side of body –
connected by the corpus callosum
• Hemispheres are not completely
symmetrical in structure nor
equivalent in function
• Concerned with “higher functions”
including sensory analysis and
perception, motor initiation
(voluntary) and coordination,
conscious thought, language and
intellect

Question 19

what are the 4 lobes that the cortex is divided into?

Answer 19

they are divided by folds
-the frontal lobe
parietal lobe
occipital lobe
-temporal lobe

Question 20

where is the occipital lobe? what it does?

Answer 20

-important i vision

contains primary and secondary visual cortex is to process vision from the eye

Question 21

what is the function of the temporal lobe?

Answer 21

-where auditory cortex is here both primary and secondary(association area) where further processes occur

Question 22

what is the function of the parietal lobe?

Answer 22

all the sensory information from the body is processes both primary and association

Question 23

what is the function of the frontal lobe?

Answer 23

-for motor function an has primary cortex which is near the premotor which is involved with the planning and initiation of movement and pre frontal is where decision making and personality comes from

Question 24

what is the somatosensory cortex? function, location

Answer 24

• The somatosensory cortex
analyses inputs from
mechanoreceptors (touch, stretch),
thermoreceptors and nociceptors
(pain) in the skin, muscle, joints and internal organs
• it is located in the parietal lobe of the cerebral cortex
• the sensory cortex receives
information from receptors on the opposite side of the body
• each area of the somatosensory cortex takes information from a specific part of the body
• there is somatotopic organisation of
the somatosensory cortex (sensory
homunculus)

Question 25

what decides the size devoted to each area in the cortex?

Answer 25

is proportional to the amount received from the area

Question 26

what is plasticity?

Answer 26

(if one area receives extra stimulation or reduced stimulation the
size of the devoted area will change accordingly) – use-dependent

Question 27

what is the pathway for sensory?

Answer 27

• from the somatosensory cortex information passes to “association
areas” where further processing occurs, before combining with other
sensory input and then information from past experience
– analysis, integration, perception

Question 28

what is the function of the motor cortex? where?

Answer 28

• The motor cortex is responsible for
voluntary movement
• It is located in the frontal lobe
• Studies by Penfield in the 1950s by
stimulation of the cortex of
conscious patients undergoing
surgery for epilepsy
• Stimulation results in movement on
the contralateral side
• Penfield mapped the motor cortex -
the motor homunculus
• Use-dependency for cortical space
• Much of the remainder of the prefrontal cortex is involved in
processing motor information
-the amount the muscle is used is proportional to the amount of cortex developed

Question 29

where does the motor cortex send signal to and from?

Answer 29

• Motor cortex sends
signals to the α-motor
neurons
• Motor cortex has input
from the
supplementary motor
area, premotor cortex,
posterior parietal
cortex, basal ganglia,
thalamus and
cerebellum
– planning,
programming,
coordination of
complex movement

Question 30

how does language affect the cortical areas involved?

Answer 30

• Language is considered to be the highest mental function in humans• In 90% of people the left hemisphere is used in relation to language• Distinct areas are specialised for the production and understanding of language
• Aphasias (language deficits resulting from brain damage) have enabled the language centres to be identified
• Broca’s area - involves the articulation of speech (controls muscles – via motor cortex - for speaking)
• Wernicke’s area - involves comprehension and planning/coherence of
language

Question 31

what is the main cell of the CNS?

Answer 31

neurone

Question 32

what is the glial cells? different types?

Answer 32

another main cell in CNS
-astrocytes
-microglial
oligodendrocytes
-ependymal

Question 33

what are astrocytes?

Answer 33

• the star looking like cell

- most abundant in CNS more than neurones

Question 34

what is the role of astrocytes?

Answer 34

Dynamic role
– Communicate with each other (gap
junctions and chemical signals) and
with neurons
• Structural support
– Including scaffold during development to keep neurone in right position
• Blood brain barrier
• Repair
– Scar tissue
• Maintenance of the extracellular
environment
– Neurotransmitters
– [K+]
• Modulation of synapse function
– Formation (due to memory)
– Maintenance
– Modification of neurotransmitter
release

Question 35

what are microglia and their role?

Answer 35

Immune cells of the CNS
– Macrophages of the CNS
• Scavengers
• Release of cytokines
• Resting or activated they perform different roles and structurally different 
– Structural differences
– Resting
• Homeostatic
– Activated
• Motile
• Pro-inflammatory
• Role in neurodegenerative disease

Question 36

what are oligodendrocytes?

Answer 36

are the cells that form the myelin sheath around neuronal axons – White matter

Question 37

what are ependymal cells and function?

Answer 37

• Epithelial cells
– Line the cavities fluid-filled cavities of the CNS (ventricles)
• Secrete cerebrospinal fluid (CSF)
• Ciliated
• Blood brain barrier