AP L1-2

• Physiology


  The study of the normal function of living organisms
• Anatomy

  The study of the body and how its parts are arranged
• Aspects required to study physiology

  • Anatomy (gross structure and microstructure)
  • Histology (study of cells and tissues)
  • Biochemistry (chemical and molecular foundation)
  • Physiology (function)
• Tissue

  A group of specialised cells that usually function together
• Four principal tissue types

  • Nervous tissues
  • Muscle tissues
  • Connective tissues
  • Epithelial tissues
• Organ

  Built from multiple tissues to accommodate different functions
• Nervous system

  A constellation of cells (neurons and glia) that are organised into functional neural circuits, which permit (complex) neural control of an animal's physiology and behaviour
• Major anatomical divisions of the vertebrate nervous system

  • Central nervous system (CNS): Brain and spinal cord
  • Peripheral nervous system (PNS): (i) Autonomic nervous system (ANS): largely outside of voluntary control; includes the enteric nervous system (ENS); (ii) somatic (motor) nervous system (SNS): under conscious (voluntary) control
• Neuron

  The functional units of the nervous system
• Glia

  Non-neuronal cells that support neurons in many ways, modulate neuronal signalling, insulate neuronal processes, and provide immune function(s) for the CNS
• Neurons

  • They communicate/convey information from sensors to CNS; store and integrate information; communicate commands (from CNS) to muscles and glands
  • They have become highly specialised to serve two primary functions: the rapid transmission of information from specific sources to selected targets via action potentials, and the integration (summation) of information/electrical activity from many sources
• The human CNS contains more than 90 billion neurons
• Afferent neuron

  Receives information from other neurons
• Efferent neuron

  Transmits information to other neurons or non-neuronal cells (e.g. muscles)
• Regions of a neuron

  • Cell body (soma)
  • Dendrites
  • Axon
  • Axon terminals
• Most neurons have only 1 axon (but multiple branching can result in many axonal terminals)
• Neuronal types

  • Purkinje cell
  • Pyramidal cell
  • Sensory neuron from the human retina
• Microglia

  Phagocytotic cells that are motile and provide the first and major immune defence mechanism in the CNS
• Macroglia

  Support and modulate the functions of neurons
• Types of macroglia

  • Astrocytes
  • Oligodendrocytes
  • Ependymal cells
• Astrocytes

  The most abundant neuroglia, with supportive functions for CNS neurons, contributing to the blood-brain barrier, regulation of neurotransmitters, and modulation of neuronal activity
• Oligodendrocytes

  Form the myelin sheath around neuronal axons in the CNS
• Ependymal cells

  Specialised ciliated epithelial cells found in the fluid-filled spaces of the brain (ventricles) and central canal of the spinal cord, producing and circulating cerebrospinal fluid
• The human brain is said to contain more than 90 billion neurons and 90 billion astrocytes
• The astrocyte to neuron ratio varies across different regions of the brain
• Microglia is not a type of glial cell
• Ganglia are clusters of neuronal cell bodies
• Vertebrates differ greatly in their behavioural complexity, and their neural networks reflect this functional diversity
• The brainstem differs less among vertebrate species than the cerebrum
• Major divisions of the brain

  • Forebrain (prosencephalon): cerebral hemisphere(s), thalamus
  • Midbrain (mesencephalon): superior & inferior colliculi
  • Hindbrain (rhombencephalon): cerebellum, pons, medulla
• The CNS develops from the embryonic neural tube
• The anterior end of the neural tube folds and swells, becoming the major divisions of the brain
• The remainder (posterior end) of the neural tube becomes the spinal cord
• Lobes of the brain

  • Primary motor cortex
  • (Primary)
  • (vision)
  • (Hearing)
• Functional magnetic resonance imaging (fMRI)

  A method for detecting the functional activity of different brain areas, by measuring changes in oxygenated blood flow as an indication of neural activity
• Grey matter contains large numbers of cell bodies, while white matter consists of large numbers of myelinated nerve fibres/axons</b>
• Nuclei

  Discrete regions of grey matter in the CNS
• Ganglia

  Clusters of neuronal cell bodies in the PNS
• Tracts

  Aggregates of white matter ('aligned' axons) which connect one part of the CNS with another
• Nerves

  Bundles of nerve fibres outside the CNS, in the PNS