#3 Bain mind and behavior

General Concepts Regarding Genetics and Evolution

  • Genotype vs. Phenotype

    • The genotype refers to the genetic constitution of an organism.

    • The phenotype refers to the observable physical traits of the organism.

  • Homozygous vs. Heterozygous

    • Homozygous: an individual has two identical alleles for a given gene (e.g., two recessives or two dominants).

    • Heterozygous: an individual has one dominant and one recessive allele for a given gene.

  • Identical Twins

    • Identical twins are genetically homozygous as they share genetic material, yet they can still exhibit varying alleles and traits.

Theories in Evolutionary Biology

  • Nature of Scientific Theories

    • Theories can be supported by evidence but cannot be definitively proven.

  • Evidence Supporting Evolution

    • Similarities in the fossil record over time.

    • Structural homology among different species.

    • Outcomes of selective breeding demonstrating phenotype changes in response to environmental adaptations.

Genetics Vocabulary

  • Key Genetic Terms

    • Chromosome: a structure made of DNA and protein that contains genes.

    • Gene: a segment of DNA that contains coding information for traits.

    • Allele: one of several forms of a gene.

    • Punnett Square: a tool used for predicting the possible genotypes of offspring from parental genotypes.

    • Genotype: specific genetic makeup of an individual.

    • Phenotype: the expression of the genotype, influenced by the environment.

    • Homologous vs. Recessive: homologous alleles affect traits and can be expressed in homozygous or heterozygous forms.

Nervous System Anatomy

  • Overview of the Nervous System

    • Divided into two main parts:

    • Central Nervous System (CNS): Consists of the brain and spinal cord.

    • Peripheral Nervous System (PNS): All other neural tissue not part of the CNS.

  • Function of CNS

    • Processes sensory information and coordinates motor responses to internal organs and muscles.

Divisions of the Peripheral Nervous System (PNS)

  • Somatic Nervous System

    • Controls voluntary movements and reflexes; responsible for motor control of skeletal muscles.

  • Autonomic Nervous System

    • Regulates involuntary physiological functions, divided into:

    • Sympathetic Nervous System: mediates the 'fight or flight' response, increasing heart rate, dilating pupils, and directing energy away from digestion.

    • Parasympathetic Nervous System: promotes 'rest and digest' functions, decreasing heart rate, constricting pupils, and facilitating digestion.

Afferent vs. Efferent Nerves

  • Definitions

    • Afferent nerves: carry sensory information to the CNS. (Mnemonic: Afferent = approaches)

    • Efferent nerves: carry motor commands from the CNS to effectors (e.g., muscles and glands). (Mnemonic: Efferent = exits)

Sympathetic vs. Parasympathetic Divisions

  • Sympathetic Division

    • Examples of functions activated:

    • Increases heart rate

    • Dilates pupils

    • Inhibits salivation and digestion

    • Prepares the body for quick action (fight or flight).

  • Parasympathetic Division

    • Examples of functions activated:

    • Decreases heart rate

    • Stimulates digestion and salivation

    • Promotes relaxation and restoration of energy.

Anatomy of the Brain

  • Basic Structures of the Brain

    • Mention of protective layers: meninges consist of dura mater, arachnoid mater, and pia mater.

    • Cerebrospinal fluid (CSF) resides in the subarachnoid space, acting as a cushion and protection for the brain.

  • Hydrocephalus

    • Condition resulting from excess cerebrospinal fluid leading to increased intracranial pressure, potentially causing brain damage or developmental issues.

Blood-Brain Barrier (BBB)

  • Structure and Function

    • Composed of tightly packed endothelial cells that prevent substances from leaking into the brain.

    • Protected from pathogens but complicates the delivery of therapeutic agents to the brain.

Neurons and Glial Cells

  • Neurons

    • Carry out electrochemical signaling and communicate via synapses.

    • Basic structure: dendrites (receive signals), cell body (integrates signals), axon (transmits signals), synapse (communicates with other neurons).

  • Glial Cells

    • Hold/support neurons and assist in various functions such as nutrient supply, immune responses, and maintaining synapse functionality.

    • Types include:

    • Astrocytes - star-shaped, maintain blood-brain barrier, nutrient supply, and repair

    • Oligodendrocytes - form myelin in CNS

    • Schwann cells - form myelin in PNS

    • Microglia - act as immune defense in the brain

  • Unique Features of Neuron Types

    • Bipolar: one axon and one dendrite.

    • Unipolar: one axon splitting into two branches.

    • Multipolar: multiple dendrites and one axon, common in the CNS.

Cell Counting Techniques

  • Methods to Count Neurons

    • Nissl Stain: allows visualization of cell bodies in fixed tissues.

    • Golgi Stain: stains the entire neuron in random samples, used to study neuronal morphology.

    • Fluorescence Microscopy: highlights different neurons with colors using genetic modifications or specific fluorescent labels.

    • Electron Microscopy: provides high-resolution images of neuronal structures, such as synaptic terminals.

  • Historical Context

    • Santiago Ramón y Cajal: pioneering work on neuron morphology using the Golgi method, won Nobel Prize for contributions to the understanding of the nervous system.

Conclusion

  • The upcoming topics will delve into the details of neuronal functions including action potentials and further anatomy of the brain.