Cells & Structures

Cells & Structures Overview

  • PSY304: Biopsychology

Seminar Announcement

  • Topic: Electrical Synapses – Functional Properties and Molecular Organization

    • Speaker: Alberto Pereda

    • Date: Thurs, Apr 3, 4 PM

    • Location: Willamette 110

Theories of Neuronal Structure

  • Reticular Theory

    • Proposed by Camillo Golgi (19th – 20th century)

    • Suggests that neurons are fused into continuous structures.

  • Neuron Doctrine

    • Proposed by Ramon y Cajal (19th – 20th century)

    • Asserts that the brain consists of separate neurons communicating at synapses (touch points).

Neuron Quantity

  • Your brain contains:

    • Approximately 100 billion neurons

    • Approximately 100 billion glial cells (support cells)

    • Approximately 1 quadrillion synapses

    • Connectome: A wiring diagram depicting all synaptic connections in the brain.

Neuron Structure and Function

  • Flow of Electrical Impulses:

    • Impulses flow from dendrites to the cell body and then along the axon (Law of Dynamic Polarization by Ramon y Cajal).

  • Neuronal Zones:

    • Input Zone: Dendrites

    • Integration Zone: Cell body

    • Conduction Zone: Axon

    • Output Zone: Presynaptic terminals

Neuronal Shapes

  • Types of Neurons:

    • Unipolar, Bipolar, Multipolar: These classifications are based on the number of processes extending from the cell body.

Synaptic Transmission

  • Components of Synapses:

    • Communication occurs via synapses formed between the presynaptic and postsynaptic neurons.

    • Synaptic Cleft: The gap between neurons.

    • Neurotransmitter Molecules: Carry signals across the synapse.

  • Information Flow Sequence:

    • From dendrite → cell body → axon → presynaptic terminal → synaptic cleft → postsynaptic membrane.

Glial Cells Functions

  • Oligodendrocytes (CNS) and Schwann Cells (PNS):

    • Insulate axons and speed up conduction (myelination).

  • Astrocytes: Regulate blood flow and recycle neurotransmitters.

  • Microglia: Clean up debris and regulate synapse formation.

Neuroanatomy

  • Anatomical Directions:

    • Dorsal: Towards the back

    • Ventral: Towards the belly

    • Anterior: Towards the front

    • Posterior: Towards the back

    • Lateral: Towards the side

    • Medial: Towards the middle

  • CNS vs. PNS:

    • Central Nervous System: Composed of the brain and spinal cord

    • Peripheral Nervous System: Composed of the somatic (voluntary) and autonomic (involuntary) systems.

Nervous System Functions

  • Nerve Functions:

    • Afferent (Sensory): Carry information to the CNS from sensory organs.

    • Efferent (Motor): Carry movement commands from the CNS to muscles and internal organs.

  • Cranial Nerves:

    • Originate in the brain; responsible for sensory, motor, or mixed functions.

Autonomic Nervous System

  • Comprised of Sympathetic (fight or flight) and Parasympathetic (rest and digest) systems, working together to maintain homeostasis.

Brain Development

  • Most neurons are present at birth, but complexity in neural connections increases over time and is pruned after about 2 years.

  • Myelination: Continues after birth, essential for infant development.

Brain Subdivisions

  • Forebrain:

    • Telencephalon (cerebral hemispheres) is responsible for higher brain functions such as thought, memory, and voluntary movement

    • Diencephalon(beneath telencephalon) is involved in sensory and motor signal relay and the regulation of sleep, alertness, and temperature.

    • Midbrain: Acts as a relay center for visual and auditory information, playing a crucial role in eye movements, hearing, and the coordination of motor functions.

    • Hindbrain: Comprised of the pons, cerebellum, and medulla oblongata; responsible for autonomic functions like breathing and heart rate, as well as coordination and balance.

  • Midbrain: Mesencephalon

  • Hindbrain: Metencephalon, Myelencephalon

  • Spinal Cord: connects with the brain visually and functionally.

Important Considerations

  • Emphasize understanding the synaptic structures, the role of glial cells, and the intricacies within the nervous system for a solid grasp of biopsychology.