65: Phylogeny and development of the nervous system (brain and spinal cord) Flashcards
What is the basic organization of nerves?
Nerves are bundles of nerve cell processes, which can be sensory, motor, or mixed.
What is the key difference between the parasympathetic and sympathetic nervous systems?
The parasympathetic nervous system calms the body, conserving energy, while the sympathetic nervous system prepares the body for action (“fight or flight”).
Where is the spinal cord located?
The spinal cord resides within the vertebral canal, extending from the brain to varying lengths depending on the presence of a tail.
What is the composition of gray matter in the spinal cord?
Gray matter is the site of processing and includes neuronal cell bodies and dendrites.
What is the composition of white matter in the spinal cord?
White matter facilitates communication across the nervous system.
What are the characteristics of Porifera (sponges) in terms of nervous system development?
Porifera lack a centralized nervous system but have neural precursor cells.
What is the structure of the nerve net in Radiata?
The nerve net in Radiata comprises sensory, intermediate, and motor neurons for basic responses.
What are the consequences of forebrain enlargement?
- Increased Complexity: Leads to more complex behaviors and enhanced muscle control.
- Limb Movement: Coordination of limb movements becomes more intricate.
- Sensory Input: There’s an increase in the amount of sensory information processed.
What are the divisions of the telencephalon and their functions?
- Dorsal Pallium:
o Medial Pallium: Processes olfactory information.
o Dorsal and Lateral Pallia: Receive and process sensory inputs like visual and auditory data. - Ventral Subpallium:
o Striatum: Manages complex movements.
o Septum: Regulates emotions and short-term memory within the limbic system.
What are the main structures and functions of the diencephalon?
- Hypothalamus: Controls bodily functions such as temperature, appetite, and emotional behavior.
- Thalamus: Acts as a sensory relay center.
- Epithalamus (including Pineal Gland): Influences skin pigmentation and regulates biological rhythms.
- Subthalamus: Performs various functions depending on species-specific needs.
How has the forebrain evolved across species?
- Reptiles: Feature three pallium divisions; lateral pallium forms a dorsal ventricular ridge (DVR).
- Birds: Possess an expanded DVR known as the WULST for higher associative functions.
- Mammals: Have an enlarged dorsal pallium or cerebral cortex, crucial for sensory processing and motor function initiation.
What are the functional types of neurons in spinal nerves?
- Somatic Efferent: Motor signals to skeletal muscles.
- Somatic Afferent: Sensory inputs from the external environment.
- Visceral Afferent: Sensory inputs from internal organs.
- Visceral Efferent: Motor signals to organs and glands.
How has the spinal cord evolved from simple to complex organisms?
- Amphioxus: No clear gray/white matter distinction; central canal surrounded by neuronal soma.
- Cyclostomata (Jawless Fishes): Features mixed dorsal roots and a clear gray matter.
- Bony Fishes: Distinguished dorsal (sensory) and ventral (motor) roots.
- Tetrapods: Gray matter arranged in an H-shaped pattern.
- Mammals: Presence of nerve plexuses and a spine generally shorter than the vertebral column.
What are the key components of the mesencephalon?
- Tectum:
o Processes visual information in optical lobes.
o Manages auditory processing in auditory lobes. - Tegmentum:
o Contains motor nuclei and pathways essential for eye movement and motor control.
o Includes structures like the red nucleus and reticular formation.
What are the significant aspects of the metencephalon?
- General: Origin for several cranial nerves.
- Cerebellum: Modifies motor output; larger in birds for advanced coordination.
- Pons: Facilitates communication between different brain regions.
