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• Physiology


  The study of function in living matter
• Fields of Physiology


  • Viral physiology
  • Bacterial physiology
  • Cellular physiology
  • Plant physiology
  • Human physiology
• Human Physiology


  Explains the specific characteristics and mechanisms of the human body that make it a living being
• Cell


  The basic unit of the body, and each organ is an aggregate of many different cells held together by intercellular supporting structures
• Basic characteristics of cells

  • Oxygen combines with carbohydrates, fat and protein to release the energy needed for cell function
  • All cells have the ability to reproduce and whenever cell are destroyed, one or another of the remaining cells divide again and again until the appropriate number is replenished
  • The general mechanisms for changing nutrients into energy are basically the same in all cells
  • All cells deliver the end-products of their chemical reactions into the surrounding fluids
• Homeostasis


  Maintenance of static, or constant condition in the environment
• Components of the Extracellular Fluid

  • Intracellular Fluid - the fluid found inside the cell which constitute most of the 40% of the total body fluid
  • Extracellular Fluid - found in the spaces outside the cells, and is in constant motion throughout the body
• Homeostatic Mechanisms of the Major Functional System

  • The Extracellular Fluid Transport System
  • Origin of Nutrients in the Extracellular Fluid
  • Removal of Metabolic End-Products
  • Regulation of Body Functions
  • Reproduction
  • Extraction of Energy from Nutrients (Mitochondria)
  • Locomotion or Movements by the cells
• Extracellular Fluid Transport System


  Transports Nutrients (Circulatory System), movement of the blood around the circulatory system and movement of fluid between the blood capillaries and the cells
• Origin of Nutrients in the Extracellular Fluid

  • The Respiratory System - transports nutrients to tissues (O2)
  • The Gastrointestinal Tract - absorption of nutrients into the extracellular fluid
  • The Liver - detoxification and storage of substances
  • Musculosketekal System - locomotion
• Removal of Metabolic End-Products

  • Removal of Carbon Dioxide by the Lungs
  • The Kidneys - removes different end products of metabolism and excess of ions and water that might have accumulated in the extracellular fluid
• Regulation of Body Functions

  • The Nervous System - muscular and secretory activities
  • The Hormones System - for metabolic function
• Reproduction - maintain static conditions by generating new beings to take the place of ones that are dying
• The principal substances from which cell extracts energy are Oxygen and one or more of the foodstuffs - Carbohydrates, Fats and Protein
• Locomotion or Movements by the cells

  • Ameboid locomotion - movements of an entire cell in relation to its surroundings, such as movement of WBC
  • Ciliary movements - the whiplike movement of cilia on the surface of the cells
• Cell


  A typical cell has two major parts: Nucleus - separated from the cytoplasm by the nuclear membrane, Cytoplasm - separated from the surrounding fluids by the cell membrane
• Chemical Components of the Cell

  • Water - the principal medium of cell which is about 70 to 80%
  • Electrolytes - provides inorganic chemicals for cellular reactions and for the operation of same cellular control mechanisms
  • Proteins - the most abundant substance next to water, it constitutes 10 to 20% of the cell mass
  • Lipids - the most important lipids are phospholipids and cholesterol which constitutes 2% of the total cell mass
  • Carbohydrates - most human cell do not maintain large stores of carbohydrates, usually averaging 1% of the total mass
• Physical Structures of the Cell

  • Cell Membrane
  • Endoplasmic Reticulum
  • Ribosomes
  • Golgi Apparatus
  • Lysosomes
  • Peroxisomes
  • Mitochondria
  • Nucleus
  • Nucleoli
  • Microfilaments and Microtubular Structures
  • Secretory Vesicles
• Ingestion by the cell (Endocytosis)

  1. Pinocytosis (Invagination) - small particles with fluid

  2. Phagocytosis (Evagination) - large particle
• Digestion of Foreign Substances in the Cell

  Immediately after a pinocytic or phagocytic vesicles appear inside a cell, lysosomes release hydrolases and begins hydrolysis of these vesicles
• Synthesis and Formation of Cellular Structures by Endoplasmic Reticulum and the Golgi Apparatus


  1. Formation of proteins by the Granular Endoplasmic Reticulum

  2. Synthesis of lipids by smooth endoplasmic reticulum

  3. Processing and formation of intracellular vesicles by the Golgi Apparatus

  
• Intracellular Fluid


  The fluid inside the cells of the body, different from the Extracellular Fluid that is outside the cells
• Components of the Extracellular Fluid

  • Interstitial Fluid - that circulates in the spaces between the cells
  • Blood Plasma Fluid - that mixes freely with the interstitial fluid through the capillary walls
• The extracellular fluid supplies the cells with nutrition and other substances needed for cellular function. Before the cell can utilize these substance, they must be transported through the cell membrane
• Characteristics of Control Systems in the Body

  • Negative Feedback Nature of Control System - a series of changes that return the factor toward a certain mean value, thus maintaining homeostasis
  • Positive Feedback - Vicious Circles; does not lead to stability but to instability and often to death
  • Adaptive Control System - feed forward and control
• The human body has thousands of control systems in it
• Examples of Control Systems in the Body

  • Regulation of oxygen and carbon dioxide concentrations in the extracellular fluid
  • Regulation of arterial pressure
• Transport Processes Through the Cell Membrane

  • Diffusion or Passive Transport - random molecular movement of substances either opening the membrane or in combination with a carrier protein caused by kinetic motion of matter
  • Active Transport - movement of ions or other substances across the membrane in combination with a carrier protein but additionally against an energy gradient, such as from a low concentration state to a high concentration state, a process that requires chemical energy to cause

  
• Diffusion Through the Cell Membrane

  • Simple Diffusion - molecular kinetic movement of molecules or ions through a membrane opening without the necessity or binding with carrier proteins in the membrane
  • Facilitated Diffusion - interaction of the molecules or ions with a carrier protein that aids its passage through the membrane, by binding chemically with fit and shuttling it through the membrane in this form

  
• Pathways of Simple Diffusion Through Cell Membrane

  • Diffusion through the lipid Bilayers - Diffusion of lipid Soluble Substances, Transport of water and other lipid-insoluble molecules
  • Diffusion through protein channels and Gating of these channels - Selectively permeable to certain substances, Many of the channels can be opened or closed by gates

  
• Ions such as sodium and potassium fail to diffuse through the lipid bilayer due to their electrical charge which impedes their movement
• Reasons for Failure of Ions to Diffuse Through Lipid Bilayer

  • Electrical charge of these ions causes water to bond within forming hydrated ions which are very large to penetrate the lipid layer
  • The electrical charge of the ion interacts with the changes of lipid bilayer
• Important Channels for Diffusion Through Cell Membrane

  • Sodium Channels - negatively - charged channels
  • Potassium Channels - not negatively charged but can allow ions to pass through because their hydrated form are smaller than sodium
• Ways the Opening and Closing of Membrane Channels are Controlled

  • Voltage Gating - the molecular conformation of the gate responds to changes in electrical potential across the membrane
  • Chemical Gating - the gate is opened or closed by the binding of a specific chemical substance
  • Mechanical Gating - the gate is opened or closed by a mechanical distortion of the membrane

  
• Lipid bilayer


  Impermeable to ions such as sodium, potassium because of the electrical charge which impedes their movement
• Causes of ions not diffusing through lipid bilayer

  1. Electrical charge of ions causes water to bond within forming hydrated ions which are very large to penetrate the lipid layer

  2. Electrical charge of the ion interacts with the changes of lipid bilayer
• Protein channels


  Selectively permeable to certain substances
• Important protein channels


  • Sodium Channels (0.3 x 0,5 nm) - negatively - charged channels
  • Potassium Channels (0.3 x 0.3 nm) - not negatively charged but can allow ions to pass through because their hydrated form are smaller than sodium
• Gating of protein channels


  Means of controlling the permeability of one channel
• Ways protein channel gates are opened/closed

  • Voltage Gating - the molecular conformation of the gate responds to the electrical potential across the cell membrane
  • Ligand Gating - some protein channels gates are/opened/by binding another molecule with the protein, this change in protein molecule opens or closes the gate