Brain: Structure and Function - Summary Notes

Brain Structure and Function: Introduction

  • Brains change as we develop, use chemical transmitters, process information, and store memories.
  • The nervous system is composed of neurons (electrical, chemical, neurotransmitters, hormones) and glial cells (support and information processing).
  • Neurons:
    • Input zone: dendrites.
    • Integration zone: cell body (soma).
    • Conduction zone: axon.
    • Output zone: axon terminals.
  • Outside CNS = nerve, inside CNS = tract.
  • Glia functions: surround neurons, supply nutrients and oxygen, synaptic transmission, clearance of neurotransmitters, insulation, destroy pathogens.
  • Human brain: 86.1 ± 8.1 billion neurons and 84.6 ± 9.8 billion non-neuronal cells.
  • Anatomical terminology: Afferent (incoming), Efferent (outgoing). Afferents Arrive, Efferents Exit.
  • Anatomical orientation: Dorsal/ventral (superior/inferior), Anterior/posterior (rostral/caudal), Medial/lateral, Horizontal/Coronal/Sagittal.

Somatic and Autonomic Nervous Systems

  • Somatic Nervous System (SNS): cranial and spinal nerves; carries sensory information to the CNS and transmits motor instructions.
  • Autonomic Nervous System (ANS): balances internal organs; sympathetic (fight or flight) and parasympathetic (rest and digest).
  • CNS: brain and spinal cord; mediates behavior.
  • Cranial Nerves: afferent sensory input and efferent motor output for head and neck.
  • Spinal Nerves: 31 pairs; sensory input via dorsal root, motor output via ventral root.
  • Sympathetic Nervous System: prepares the body for action; neurons in spinal cord innervate the sympathetic chain.
  • Parasympathetic Nervous System: neurons arise in cranial nerves and sacral spinal cord; opposes sympathetic activity.

Central Nervous System

  • Surface Features of the Brain:
    • Meninges: Scalp, Skull, Dura mater, Arachnoid membrane, Subarachnoid space, Pia mater.
    • Gyri (gyrus) and Sulci (sulcus).
    • Lobes: Frontal, Parietal, Occipital, Temporal.
  • Internal Features:
    • Grey Matter and White Matter.
    • Cerebral Ventricles: Lateral, Third, Fourth - filled with CSF (shock absorber, exchange medium).
  • CNS components: Spinal Cord, Brainstem, Cerebellum, Midbrain, Diencephalon, Forebrain.
  • Spinal Cord: segmented switching stations for sensory input and motor output.
  • Hindbrain and Cerebellum: motor functions, breathing, balance, fine movement.
    • Cerebellum: motor and non-motor learning, inhibitory messages via Purkinje cells.
  • Midbrain: Tectum (sensory - superior and inferior colliculi), Tegmentum (motor - red nucleus, substantia nigra).
  • Diencephalon: Thalamus (relay center), Hypothalamus (hormone control via pituitary gland).
  • Forebrain: Cortex, Basal Ganglia, Limbic System.
  • Cortex: divided into four lobes; Projection, Association, and Commissural tracts.
  • Basal Ganglia: motor control; caudate nucleus, putamen, globus pallidus, substantia nigra.
  • Limbic System: emotions, learning, memory; amygdala, hippocampus, cingulate gyrus, olfactory bulb.
  • Brain Imaging: CT (X-rays), PET (radioactive tracer), MRI/fMRI (magnetic fields, blood flow).

Endocrine System

  • Chemical signals (hormones) secreted into the bloodstream affect cells with receptors.
  • Major Glands: Hypothalamus, Pineal, Pituitary, Thyroid, Adrenal, Pancreas, Gonads.
  • Hormone Dysregulation: e.g., thyroid (hyper/hypothyroidism), adrenal, pancreas (diabetes), gonads (Kallman syndrome).

Key Concepts

  • Neurons and Glia
  • Anatomy Language
  • Somatic (sensation, movement) and Autonomic (sympathetic/parasympathetic) Nervous Systems
  • Brain Anatomy (surface and internal features)
  • Brain Systems (cortex, limbic system, basal ganglia)
  • Brain Imaging Techniques (CT, PET, MRI)
  • Endocrine System (glands and functions)