Week 3- Introduction to CNS+cerebral cortex+glial cells Flashcards
what is the components of the CNS?
-BRIAN AND SPNAL CORD
what is the brain divided into?
– Brain stem – Cerebellum – Forebrain • Diencephalon • Cerebrum
what component of the brain is connected to the spinal cord?
brain stem
what is the brain stem sub divided into?
- medulla oblongata
- midbrain
what is the brain stem? what it does?
-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
what is the reticulum formation?
– Network of neurons throughout the brain stem – Receives and integrates sensory input • “filtering” un-necessary information – Consciousness – Arousal (wakefulness) • Reticular activating system
what type of function and what happens in the medulla oblongata?
– 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))
what is found in the midbrain?
– Contains the substantia nigra
Parkinson’s disease
what is the cerebellum? where it is, involved?
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
what is the diencephalon divided into?
thalamus
hypothalamus
what is thalamus? where and function
-above the mid brain – Relay centre • Sensory input (all via thalamus: preliminary processing, filtering, directing of signals) – Directing attention • Motor control
what is the function of the hypthalamus?
– 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
what is the limbic system? where,
• 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
what is the cerebrum? consist of?
• Consists of the cerebral cortex and the basal nuclei (basal
ganglia)
what is the basal nuclei?
• 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)
what is the function of the basal nuclei?
• 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)
what is the cerebral cortex? consist of?
• 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
what does the cerebral cortex consist?
• 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
what are the 4 lobes that the cortex is divided into?
they are divided by folds -the frontal lobe parietal lobe occipital lobe -temporal lobe
where is the occipital lobe? what it does?
-important i vision
contains primary and secondary visual cortex is to process vision from the eye
what is the function of the temporal lobe?
-where auditory cortex is here both primary and secondary(association area) where further processes occur
what is the function of the parietal lobe?
all the sensory information from the body is processes both primary and association
what is the function of the frontal lobe?
-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
what is the somatosensory cortex? function, location
• 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)
what decides the size devoted to each area in the cortex?
is proportional to the amount received from the area
what is plasticity?
(if one area receives extra stimulation or reduced stimulation the
size of the devoted area will change accordingly) – use-dependent
what is the pathway for sensory?
• 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
what is the function of the motor cortex? where?
• 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
where does the motor cortex send signal to and from?
• 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
how does language affect the cortical areas involved?
• 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
what is the main cell of the CNS?
neurone
what is the glial cells? different types?
another main cell in CNS -astrocytes -microglial oligodendrocytes -ependymal
what are astrocytes?
- the star looking like cell
- most abundant in CNS more than neurones
what is the role of astrocytes?
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
what are microglia and their role?
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
what are oligodendrocytes?
are the cells that form the myelin sheath around neuronal axons – White matter
what are ependymal cells and function?
• Epithelial cells – Line the cavities fluid-filled cavities of the CNS (ventricles) • Secrete cerebrospinal fluid (CSF) • Ciliated • Blood brain barrier
