Overview of the Central Nervous System and Its Functions

Central Nervous System (CNS)

Largest, most complex part of CNS consisting of the brain and spinal cord.

Brain

Largest part of the CNS located in the cranial cavity.

Spinal Cord

Communication link between CNS & PNS; reflex center located in the vertebral canal.

Meninges

Protective layers of the CNS consisting of Dura Mater, Arachnoid Mater, and Pia Mater.

Dura Mater

Tough, outermost layer of the meninges.

Arachnoid Mater

Web-like, middle layer of the meninges.

Pia Mater

Thin, innermost layer that hugs the brain and spinal cord.

Ventricles

Cavities in the brain that are continuous with the spinal cord's central canal.

Cerebrospinal Fluid (CSF)

Fluid secreted by the choroid plexus that circulates in ventricles & subarachnoid space, providing nutrient supply, waste removal, ion balance, and shock absorption.

CSF Volume

Approximately 150 ml; replaced 3-4 times per day with 500 ml produced daily.

Cerebrum

Part of the brain with structures like gyri, sulci, and fissures, responsible for voluntary movement, sensory perception, memory, reasoning, and personality.

Gyri

Ridges on the surface of the cerebrum.

Sulci

Shallow grooves on the surface of the cerebrum.

Fissures

Deep grooves on the surface of the cerebrum.

Corpus Callosum

Structure that connects the two hemispheres of the brain.

Motor Areas

Areas in the frontal lobe responsible for voluntary movement, including Broca's area for speech.

Sensory Areas

Areas responsible for processing sensory information, located in different lobes of the brain.

Hemispheric Dominance

The concept that the left hemisphere is dominant for language, math, and logic in 90% of people, while the right hemisphere is dominant for artistic, spatial, and emotional tasks.

Memory Types

Short-term memory involves electrical, temporary circuits; long-term memory involves structural neuronal changes and synapse strengthening.

Basal Nuclei

Masses of gray matter involved in motor control and dopamine release; associated with disorders like Parkinson's disease.

Diencephalon

Part of the brain located between the cerebral hemispheres and brainstem, including the thalamus, hypothalamus, and limbic system.

Thalamus

Part of the diencephalon that acts as a sensory relay (except for smell).

Hypothalamus

Part of the diencephalon that maintains homeostasis and links the nervous and endocrine systems.

Limbic System

Part of the diencephalon involved in emotions and motivation.

Brainstem

Part of the brain that includes the midbrain, pons, and medulla oblongata, responsible for basic life functions.

Cerebellum

Part of the brain located posterior to the brainstem, coordinating voluntary movement, balance, and posture.

Peripheral Nervous System (PNS)

Nervous system outside the CNS, consisting of cranial and spinal nerves.

Cranial Nerves

12 pairs of nerves in the PNS that can be sensory, motor, or mixed.

Spinal Nerves

31 pairs of mixed nerves in the PNS.

Somatic Nervous System

Part of the PNS that controls skeletal muscles and is voluntary.

Autonomic Nervous System

Part of the PNS that controls involuntary functions, including smooth muscle and glands.

Sympathetic Nervous System

Part of the autonomic nervous system responsible for the fight or flight response.

Parasympathetic Nervous System

Part of the autonomic nervous system responsible for rest and digest functions.

Life-Span Changes

Changes in the nervous system with age, including brain shrinkage, neuron loss, and decreased neurotransmitters.

Hydrocephalus

CSF accumulation due to blockage

Phineas Gage

Frontal lobe damage → personality change

Lumbar Puncture

CSF sampling for diagnosis

Cerebrum

One of the four main parts of the brain

Diencephalon

One of the four main parts of the brain

Brainstem

Structure that connects the brain to the spinal cord

Cerebellum

One of the four main parts of the brain

Meninges

Three layers of protective tissue surrounding the brain and spinal cord

Dura mater

Outermost layer of the meninges

Arachnoid mater

Thin and web-like meningeal layer

Pia mater

Innermost layer of the meninges

Cerebrospinal fluid (CSF)

Protects the CNS, provides nutrients, removes waste, and maintains ion balance

Choroid plexus

Where CSF is produced

Frontal lobe

Responsible for reasoning, planning, and voluntary movement

Occipital lobe

Responsible for vision

Parietal lobe

Responsible for sensory interpretation

Temporal lobe

Responsible for hearing and memory

Corpus callosum

Connects the two cerebral hemispheres and allows communication between them

Motor areas

Control movement

Sensory areas

Interpret sensory input

Association areas

Process higher-level functions like reasoning and emotion

Thalamus

Acts as a relay station for sensory impulses to the cerebral cortex

Hypothalamus

Regulates vital functions like body temperature, hunger, thirst, heart rate, and endocrine activity

Limbic system

Controls emotional responses and influences behavior; produces feelings like fear and pleasure

Pons

Part of the brainstem that regulates breathing rate and depth

Reticular formation

Inhibition leads to sleep or unconsciousness

Cerebellum

Coordinates voluntary movements and maintains posture/balance

Short-term memory

Electrical and temporary

Long-term memory

Involves structural changes and enhanced synapses

Somatic Nervous System

Controls voluntary movements

Autonomic Nervous System

Regulates involuntary functions

Sympathetic nervous system

Prepares for stress ('fight or flight')

Parasympathetic nervous system

Supports rest and digestion

Vagus nerve

Responsible for visceral organ control

Aging changes in the nervous system

Loss of neurons, decreased neurotransmitters, slower response times

Frontal lobe (aging)

Brain region that loses the most neurons by age 90