Psicobiologia

1. Cells of the C S and developmental origin (slides 1-2, 12-13):→ Neurons: Specialized cells for the reception, conduction, and transmission of electrochemical signals. Many sizes and shapes → Glial cells: Outnumber neurons 10:1. There are four classes: • Oligodendrocytes – extensions rich in myelin. They create myelin sheaths in CNS. Provide a cover sheath of myelin to axons of the CNS •Schwann cells – similar to function of oligodendrocytes but in PNS. They can guide axonal regeneration. Provide a cover sheath of myelin to axons of the PNS • Astrocytes – largest glia, starshaped. They detect neural activity and regulate adjacent capillaries to control blood flow, supplying neurons with more energy when they are active. • Microglia – involved in response to injury or disease.

Cellsof the haematopoietic system and CNS are depicted, with arrows indicating lineage relatedness. Microglia are the only haematopoietic cells found in the parenchyma of the C S. 2.Anatomy of a neuron (slides 4-9): According to shape, neurons can be classified into three principal types: → Multipolar neurons have many dendrites and a single axon (most common). → Bipolar neurons have a single dendriteat one end of the cell and a single axon at the other end (common in sensory systems) Cellular extensions called dendrites serve as an output zone, receiving information from other neurons. → Unipolar (or monopolar) neurons. Have a single extension (or process) usually thought of as an axon, that branches in two directions after leaving the cell body. One end is the input zone with branches likedendrites, the other, the output zone (touch, from body into spinal cord).

There are four distinctive zones in a typical neuron: → Input zone. Cellular extensions called dendrites serve as an output zone, receiving information from other neurons. → Integration zone. A cell body region or soma, which contains the cell¡¦s nucleus, may receive additional synaptic contacts. In most types ofneurons, inputs are combined and transformed in the cell body, which serves as an integration zone. → Conduction zone. A single extension, the axon, leads away from the cell body and serves a conduction zone, transmitting the cell's electrical impulse away from the cell body. → Output zone. Specialized swellings at the ends of the axon, the axon terminals (synaptic boutons), are a functional output zoneThey communicate the cell's activity to other cells at synapses.

3. euron membrane (slides 10-11):

→ Phospholipids are the basis of membrane structure: Polar, hydrophilic head Two non‐polar, hydrophobic tails → Hydrophobic and hydrophilic interactions drive phospholipids into bilayers: Double row of phospholipids Polar heads face outward and inward Non‐polar tails mingle within the membrane5. Synapses (slide 14): Axons have three distinct zones: . Axon hillock: a cone shaped projection of the cell body. It is an integration zone, gathering information from all the synapses on the neuronfs dendrites and soma, then triggering an electrical impulse that carries the neuronfs message down the axon toward its targets . Tubular region: carries the electrical impulse. It is usuallymyelinated. . Axon terminal: where the neuron transfers information to other neurons (dendrites and soma). Contacts between neurons are called synapses. A synapse has three main components: . Presynaptic membrane on the axon terminal of the presynaptic neuron. . Postsynaptic membrane on the surface of the dendrite or cell body of the postsynaptic neuron. It

contains many synaptic vesicles. .Synaptic cleft,. the gap of about 20]40 nanometers (nm) that separates the presynaptic and postsynaptic membranes. It contains a high density of receptors. 6. Resting membrane potential: distribution of ions and types of transport (slides 15- 20): → All living cells possess an electrical charge, they are more negative on the inside than on the outside (a legacy of their evolutionary origins when...