Overview of Nervous System Organization and Functions

Cnidarians

Simplest animals with nerve nets, no central control.

Echinoderms

Sea stars with central control and nerve signals.

Bilateria

Organisms with varied nervous systems and brain structures.

Platyhelminthes

Flatworms with simple CNS and eyespots.

Annelids

Segmented worms with complex brains and ganglia.

Vertebrates

Animals with a brain and spinal cord.

Central Nervous System (CNS)

Brain and spinal cord controlling body functions.

Peripheral Nervous System (PNS)

Nerves and ganglia outside the CNS.

Glial Cells

Support cells in the CNS, aiding neurons.

Microglia

Scavenger cells protecting the brain from pathogens.

Astrocytes

Support blood flow and form blood-brain barrier.

Ependymal Cells

Produce and support cerebrospinal fluid movement.

Oligodendrocytes

CNS cells myelinating multiple axons.

Schwann Cells

PNS cells myelinating one axon each.

Myelin Sheath

Insulation preventing signal loss in axons.

Radial Glial Cells

Scaffold neurons in developing embryos.

Reflex Actions

Rapid involuntary responses, like knee-jerk reflex.

Afferent Neurons

Sensory neurons transmitting information to CNS.

Efferent Neurons

Motor neurons transmitting signals from CNS.

Autonomic Nervous System

Controls involuntary functions like digestion and heart.

Cerebral Cortex

Outer gray matter layer for higher brain functions.

Cerebellum

Coordinates movement and balance.

Thalamus

Main input area routing sensory information.