PHYSIO

• Physiology


  The study of the function of living systems
• The discussion of physiology in this module will incorporate information from texts on human physiology but will particularly focus on the physiology of animals to give justice to their distinct physiological functions
• This module will emphasize the physiology of animals to appreciate their unique physiological systems
• Levels of organization of the body

  • Chemical level
  • Cellular level
  • Tissue level
  • Organ level
  • Organ system level
  • Organismal level
• Homeostasis


  A relatively steady state that is maintained within an animal despite a wide range of environmental conditions
• Autoregulation


  Regulation that occurs at either the cellular, tissue, organ or organ system level
• Homeostatic regulatory mechanisms


  • Autoregulation
  • Extrinsic regulation
• Extrinsic regulation


  Involves the coordinated action of the nervous and endocrine systems
• Components of regulatory mechanisms

  • Receptor
  • Control center
  • Effector
• Negative feedback system


  The control system initiates changes that counteract the stimulus which will either reduce or eliminate the stimulus, thus, reestablishing the variable near its set point to maintain homeostasis
• Negative feedback system


  • Body temperature regulation

  
• Positive feedback system


  The animal elicits regulatory mechanisms that augment the effect of a stimulus
• Positive feedback system


  • Blood clotting
  • Childbirth
• Physiology is the study of the function of living systems
• Levels of organization of the body

  • Chemical
  • Cellular
  • Tissue
  • Organ system
  • Organismal

  
• Extrinsic regulation


  Coordinated action of the nervous and endocrine systems
• Regulatory mechanisms


  • Receptor
  • Control center
  • Effector
• Negative feedback system


  Counteracts the stimulus which will either reduce or eliminate the stimulus
• Positive feedback system


  Elicits regulatory mechanisms that augment the effect of a stimulus
• The cell membrane (CM) or plasma membrane is a double layer of phospholipid molecules with protein molecules embedded within it

  
• Glycocalyx


  A loose carbohydrate coat found on the entire outside surface of the cell composed of proteoglycans glycoproteins/glycolipids

  
• Selectively permeable membrane


  Certain substances can easily move into the cells while other substances may require specialized transport systems
• Membrane transport systems


  • Pores in the CM
  • Diffusion
  • Active transport mechanisms

  
• Simple diffusion


  Kinetic movement of molecules or ions through a membrane opening or intermolecular spaces without any interaction with carrier proteins

  
• Facilitated diffusion


  Carrier-mediated diffusion in which a substance diffuses through the membrane using a specific carrier protein

  
• Gating of protein channels

  Voltage gating and chemical (ligand) gating

  
• Primary active transport


  Energy is derived directly from the breakdown of ATP or some other high-energy phosphate compound
• Secondary active transport


  Energy is derived secondarily from the energy that has been stored in the form of ionic concentration differences of secondary molecular or ionic substances between the two sides of a cell membrane
• Co-transport of glucose and amino acids along with sodium ions


  Occurs especially through the epithelial cells of the intestinal tract and the renal tubules of the kidneys to promote absorption of these substances into the blood

  
• Sodium counter-transport of calcium and hydrogen ions

  Occurs through all or almost all cell membranes, with sodium ions moving to the interior and calcium/hydrogen ions to the exterior

  
• Endocytosis


  Specialized function used by very large particles to enter cell membrane, including pinocytosis and phagocytosis

  
• The cytoplasm is the fluid that fills the interior of the cell providing support
• Cytoskeleton


  Structure that helps cells maintain their shape and internal organization, and provides mechanical support that enables cells to carry out essential functions

  
• Nucleus


  Control center of the cell, surrounded by a nuclear membrane and contains the chromosomes composed of DNA
• Organelles


  • Mitochondria
  • Ribosome
  • Endoplasmic reticulum
  • Golgi apparatus
  • Lysosomes
  • Peroxisomes
  • Centrosome and centrioles
  • Cilia and flagella
• Mitochondria


  Responsible for cellular respiration and the site where energy in the form of ATP is stored

  
• Ribosome


  Site of protein synthesis
• Endoplasmic reticulum (ER)


  Rough ER functions in the transport of proteins synthesized from ribosomes, smooth ER functions in the synthesis and transport of lipids and steroids

  
• Golgi apparatus


  Processes ER vesicles to form lysosomes, secretory vesicles, and other cytoplasmic components, adds carbohydrate molecules in proteins, and synthesizes carbohydrates that cannot be formed in the ER

  
• Lysosomes


  Contains hydrolases and provide an intracellular digestive system