9 - Nervous System Organization Flashcards
What’s the CNS and the PNS?
Central Nervous System (CNS) - brain and spinal cord
Peripheral Nervous System (PNS) - nerve fibres that carry information between the CNS and other parts of the body
What are the three functional classes of neurons?
- Afferent neurons
- Efferent neurons
- Interneurons (found in CNS)
What are the components and function of the CNS?
Components:
- Cerebral cortex
- Cerebellum
- Basal nuclei
- Brain stem
- Hypothalamus
- Thalamus
What protects the CNS?
- Glial cells - 90 % of the cells within CNS, also called neuroglia cells
- Astrocytes - most abundant glial cell and fill a number of critical functions
- Microglia - immune cells of the CNS
- Ependymal - line cavities and contribute to formation of CSF
What is the blood-brain barrier?
- Shields brain from harmful changes in the blood
- Consists of endothelial cells
- Tight junctions prevent exchange across the capillary wall
(**Lipid soluble substances such as oxygen and alcohol can penetrate cells)
What is the role of oxygen and glucose in the brain?
- Brain is highly dependent on constant blood supply, can’t produce ATP in absence of oxygen
- Brain does not store glucose as well
- Damage occurs if oxygen is cut off for ~5 minutes or glucose for > 15 min
What is structure of cerebral cortex?
- Two halves (right and left cerebral hemispheres)
- Thin outer shell of gray matter (densely packaged neuronal cell bodies) on each hemisphere
- Bundles or tracts of myelinated nerve fibres constitute the white matter (transmit signals)
- Corpus callosum allows two hemispheres to communicate
What is plasticity and neurogenesis?
- Ability to change or be functionally remodelled in response to demands placed on it
- When an area of the brain is destroyed, other areas of the brain may gradually assume functions of damaged region
What’s the pathway from sensory input to motor ouput?
- Sensory input
- Primary sensory areas
- Higher sensory areas
- Association areas
- Higher motor areas
- Primary motor cortex
- Motor output
What are the left vs right side of the cerebral hemispheres for?
- Left side is most commonly the dominant hemisphere for fine motor control, so most people are right-handed
- Left side: logica, analytical, sequential, verbal tasks
- Right side: non-language skills, spatial perception, arts, music talents
What is the basal ganglia?
- Consists of several masses of grey matter located deep within the cerebral white matter
- Plays a complex role in movement
What’s the Thalamus?
- Deep in the brain near the basal ganglia
- Serves as a relay station and integration center
What’s the hypothalamus?
- The hypothalamus is an integrating centre that lies beneath the thalamus
- Multifunctional (regulating the internal environment)
What’s the limbic system?
- Limbic system surrounds the brain stem
- Interconnected ring of forebrain structures:
1. Emotion (amygdala)
2. Basic behavioural patterns
3. Reward and punishment centres
What are the three components of the brain stem?
- Pons
- Medulla oblongata
- Midbrain