McKinley_-_3E_-_CH_13_-_Brain_Cliff_Notes_Version_-_ACTIVE

Chapter 13 – The Brain

Overview of Neurons

• Estimated to contain 85 to 100 billion neurons depending on the source.

• Each neuron synapses with a minimum of 1,000 other neurons.

• High degree of interconnectivity within the brain.

Major Brain Areas and Their Functions

Area 1 – The Brain Stem

• Controls basic, important survival functions including:

  • Breathing

  • Lapping (drinking)

  • Swallowing

  • Chewing

  • Heart rate

  • Blood pressure

  • Vomiting

  • Sneezing

Area 2 – The Cerebellum

• Regulates balance and equilibrium.

• Coordinates skeletal muscle movements.

• Known as the second brain or little brain.

• Contains Arbor Vitae, white matter within the cerebellum that resembles a tree.

Area 3 – The Diencephalon

• Central core of the brain.

  • Thalamus:

    • Acts as a grand central station for all incoming sensory information (except smell).

    • Odor sensations processed through the olfactory bulbs into the limbic system.

    • Routes sensory information to appropriate areas of the cerebral cortex.

  • Hypothalamus:

    • Located anterior and slightly below the thalamus.

    • Controls endocrine system and autonomic nervous system.

    • Major part of the limbic system, involved with primitive survival emotions (e.g., nurturing, protection).

  • Epithalamus:

    • Posterior to the thalamus.

    • Produces melatonin via the pineal gland, affecting sleep cycles.

    • Contains the habenular nucleus, linked to emotions and memories related to odors.

Area 4 – The Cerebral Cortex (Cerebrum)

• The outer gray matter part of the brain.

• Site of rational, logical, and creative thinking.

• Divided into:

  • Posterior Cerebral Cortex (posterior to the central sulcus):

    • Area 3-1-2: Primary somatosensory cortex, receiving information from the skin, muscles, and joints.

    • Area 17: Primary visual cortex for visual information from the eyes.

    • Areas 41 and 42: Primary auditory cortex for sound information.

  • Anterior Cerebral Cortex (anterior to central sulcus):

    • Area 4: Primary motor cortex controlling voluntary skeletal movements.

    • Areas 6, 8, 9, 10, and 11: Frontal cortex managing executive functions, language, and speech.

Language and Speech Areas

• Wernicke’s Area: Involved in language comprehension, located in areas 39, 40, 41, and 42.

• Broca’s Area: Responsible for speech production, located in areas 44 and 45.

Association Areas of the Cerebral Cortex

• Involved in processing and associating sensory information, forming opinions about sensory experiences.

• Example of Vision:

  • Primary Visual Cortex (Area 17).

  • Visual Association Areas: Areas 18, 19, 37, etc.

• Example of Hearing:

  • Primary Auditory Cortex (Areas 41 and 42).

  • Auditory Association Areas: Area 40 and parts of Areas 22 and 39.

• Example of Touch:

  • Primary Somatosensory Cortex (Areas 3-1-2).

  • Touch Association Areas: Areas 5 and 7, etc.

Additional Brain Features

• Cranial Nerves: Twelve pairs that connect to the brain.

• Meninges: Three protective layers surrounding the brain.

• Ventricles: Four chambers containing cerebrospinal fluid.

• Choroid Plexus: Produces cerebrospinal fluid.

• Blood-Brain Barrier: Mechanism protecting the brain from circulating pathogens.

• Cerebral Lateralization: Left brain vs. right brain dominance.

Brain Activity Measurement

• Electroencephalograms (EEGs) measure brain wave patterns.

  • Alpha waves: Relaxed, eyes closed.

  • Beta waves: Alert and aware state.

  • Theta waves: Associated with deep delta sleep or stress.

  • Delta waves: Present during deep sleep.

Sleep Cycle Overview

• Sleep is a vital activity involving stages:

  • Starts from Beta (awake) to Alpha, then Theta, and Delta sleep.

  • Non-REM sleep lasts 60-90 mins, then transitions to REM sleep, which includes dreaming.

  • During sleep cycles, 75% of sleep time is non-REM and 25% is REM.

• Normal sleep pattern can involve waking multiple times.