Chapter 12: Central Nervous System

What is the central nervous system (CNS)?

The CNS consists of the brain and spinal cord; it receives, processes information, and coordinates responses.

What are the four major brain regions of the CNS?

Cerebrum, diencephalon, brain stem, and cerebellum.

What distinguishes gray matter from white matter in the CNS?

• Gray matter - consists mostly of neuron cell bodies and nonmyelinated processes

  • Where information processing occurs

  • Appears darker due to the presence of cell bodies and unmyelinated fibers

• White matter - contains mostly of myelinated axons that carry signals

  • Looks lighter due to the myelin sheaths covering the axons

What is the primary function of the cerebrum?

Responsible for conscious awareness, thought, memory, language, sensation, and voluntary movement

What three layers make up the cerebrum?

The three layers of the cerebrum are:

1. Cerebral cortex (superficial layer of gray matter)

2. Internal white matter

3. Basal ganglia deep within white matter

How is the cerebrum divided?

The cerebrum is divided into two hemispheres, the left and right, which are further subdivided into lobes: frontal, parietal, temporal, occipital, and insular

What are functions of the five lobes of the cerebral hemispheres?

1. Frontal: Executive function, like planning and organizing); higher order thinking, behavior, and problem-solving; motor control (i.e. motor cortex)

2. Parietal: Somatic sensory processing, including touch and information from muscles/joints; sensory integration (i.e. sensory cortex); spatial reasoning/awareness

3. Temporal: Hearing, smell, memory, and language comprehension

4. Occipital: vision

5. Insula: taste, vestibular awareness, and visceral awareness

What is the difference between gyri, sulci, and fissures?

Gyri are the raised folds/ridges on the surface of the brain, sulci are the grooves between the gyri, and fissures are deep divides that separate larger regions of the brain.

What are the three major sulci of the brain and what lobes do they separate?

1. Central sulcus - Separates frontal and parietal lobes

2. Lateral sulcus - Separates the temporal lobe from the frontal and parietal lobes

3. Parietooccipital sulcus - Separates parietal and occipital lobes

What are the two major fissures of the brain?

The two major fissures of the brain are the longitudinal fissure, which separates the left and right cerebral hemispheres, and the transverse cerebral fissure, which separates the cerebrum from the cerebellum.

What laterilizations occur in the left and right hemispheres of the brain?

• Left hemisphere: Language, math, and logic

• Right hemisphere: Visual-spatial skills, intuition, emotion, and artistic/musical skills.

What is the role of the diencephalon in the brain and what are its parts?

The diencephalon relays information, regulates internal balance, and connects the cerebrum to the rest of the nervous system.

It consists of the thalamus, hypothalamus, and epithalamus.

What are the functions of the thalamus, hypothalamus, and epithalamus?

1. Thalamus - acts as a relay center for sensory information

2. Hypothalamus - regulates homeostasis and controls the endocrine system (via the pituitary gland)

3. Epithalamus - involved in regulating circadian rhythms and sleep (via the pineal gland)

What is the main function of the brain stem?

The brain stem connects the brain and spinal cord, controlling vital automatic functions such as heartbeat and breathing.

What are the three parts of the brain stem and their functions?

1. Midbrain - involved in vision/motor reflexes and arousal

2. Pons - regulates vital functions such as breathing and communication between brain regions

3. Medulla oblongata - controls autonomic functions like heartbeat and blood pressure

What is the function of the cerebellum?

The cerebellum fine-tunes movement, coordination, posture, and balance.

What are the three layers of meninges surrounding the CNS?

Dura mater (tough outer layer), arachnoid mater (middle web-like layer), and pia mater (delicate inner layer).

What does cerebrospinal fluid (CSF) do?

• Buoyancy - makes the brain effectively much lighter, reducing pressure from its own weight

• Protection - cushions the CNS against blows and other trauma

• Chemical stability - carries nutrients and chemical signals and helps remove wastes

What is the significance and function of the blood brain barrier?

The blood-brain barrier (BBB) is crucial for maintaining the brain's environment by selectively permitting certain substances to enter while keeping out potentially harmful ones, thus protecting neural tissue.