Lesson 08: Organization of the Nervous System

Neurons

These are fundamental units of the nervous system that conduct electrochemical impulses

Cell body, dendrites, axon

What are the three major parts of a neuron?

Cell body

This part of the neuron contains the nucleus and integrates incoming signals.

dendrites

This part of the neuron are short, branched structures that receive electrochemical signals and send them to the cell body.

Axon

This part of a neuron is a long projection that transmits impulses away from the cell body.

myelin sheath

The ______________insulates the axon and increases impulse transmission speed.

Nodes of Ranvier

__________________ are gaps in the myelin that help speed up nerve signal conduction.

white matter

Myelinated axons

gray matter

Unmyelinated regions

Schwann Cells

___________________ form the myelin sheath in the PNS

Oligodendrocytes

________________ form the myelin in the CNS

Central nervous system

This subdivision of the nervous system is composed of the brain and spinal cord

Peripheral nervous system

This subdivision of the nervous system is composed of sensory and motor neurons

Somatic nervous system

Motor pathway that controls voluntary movements (skeletal muscles)

Automatic nervous system

Motor pathway that controls involuntary functions (heart rate, digestion).

Sensory neurons

Carry signals toward the CNS from sensory receptors.

Motor neurons

Carry signals away from the CNS to effectors (muscles & glands).

Sympathetic division

Division of the ANS active in fight or flight situations

Parasympathetic division

Division of the ANS active in rest and digest situations

human cerebum

The largest and most developed region of the brain

corpus callosum

Connects the left and right hemispheres of the cerebrum

Frontal lobe

The lobe nivolved in higher order rthinking, decision making, and voluntary movement

Parietal lobe

This lobe is involved in spatial awareness, mathematical reasoning, and sensory input proccessing

Temporal lobe

This lobe processes auditory information and laguage

Occipital lobe

This lobe is responsibel for vision processing

Cerebral cortex

The outer layer of the cerebrum, densly packed with neurons

The highly convoluted surface

What feature of the cerebral cortex increases surface area for neural activity?

Forebrain

Includes the thalamus, hypothalamus, and cerebrum (higher-order processing, learning, and memory).

Midbrain

Processes sensory information (especially vision)

Hindbrain

Includes the cerebellum, medulla oblongata, and pons (motor coordination and basic survival functions).

Hindbrain, midbrain, and forebrain

The three sections of the brain

Gray matter

This inner zone of the spinal cord contains neuron cell bodies

White matter

This outer zone of the spinal cord contains myelinated axons transmitting signals

Spinal cord (CNS)

Involved in reflex actions and relays signals between brain and the body

nerves and ganglia

The peripheral nervous system (PNS) is composed of _____________ outside the CNS.

Reflex

A rapid, involuntary response to stimulus. Allows the body to react quickly without involving the brain.

Stimulus activates sensory receptor

What is the first step of a reflex?

A sensory neuron carries the impulse to the spinal cord

What happens in a reflex after the stimulus activates a sensory receptor?

Interneuron

This (if present) processes the signal in a reflex arc

Monosynaptic reflex

reflex involving only one synapse

Opposing

The sympathetic and parasympathetic systems have ____________ effects in regulating body functions.

Homeostasis

the nervous system works with other systems to maintain…