Human Physiology

• Physiology


  Study of the functionality of living organisms at the cellular, organ, and systemic levels
• Anatomy


  Study of structures associated with human body: organelle, cells, tissues, organs and organisms
• Anatomy


  Study of structures
• Physiology


  Study of functionality
• Anatomy and physiology are closely related as physiology studies the relationship between structure and function
• Levels of organization

  • Subatomic particles
  • Atom
  • Molecule
  • Macromolecule
  • Organelle
  • Cell
  • Tissue
  • Organ
  • Organ system
  • Organism
• Organ systems


  • Skeletal system
  • Muscular system
  • Integumentary system
  • Nervous system
  • Endocrine system
  • Cardiovascular system
  • Lymphatic system
  • Digestive system
  • Respiratory system
  • Urinary system
  • Male and Female reproductive system
• Key functions of organ systems

  • To sustain life
  • Circulation - movement of substances in body fluids
  • Movement - change in position; motion
  • Responsiveness - reaction to a change
  • Growth - increase in body size; no change in shape
  • Reproduction - production of new organisms and new cells
  • Respiration - obtaining oxygen; removing carbon dioxide; releasing energy from foods
  • Digestion - breakdown of food substances into simpler forms
  • Excretion - removal of wastes produced by metabolic reactions
• There is integration between the different systems of the body
• Homeostasis


  Stable operating conditions in the internal environment
• Homeostasis


  • It is the continuous dynamic response to the ever changing external and internal environments to maintain functionality of the body
  • It is not a static state of balance
  • The body is always working towards making the internal environment constant
• When the body fails to balance homeostasis


  Constant imbalance will lead to dysfunction/disorders
• Components of homeostasis

  • Brain
  • Spinal cord
  • Negative feedback
  • Positive feedback
• Cell


  • The basic living unit of structure & function of the body
  • There are over 100 trillion cells in the body
  • Cells are highly organized, with a variety of shapes and sizes
  • Each type of cell has a special function
• Characteristics of all cells


  • General cell structure & components
  • General mechanisms for changing nutrients to energy
  • Deliver end products into their surrounding fluid
  • Almost all have the ability to reproduce
• Principal parts of a cell

  • Plasma (cell) membrane
  • Cytoplasm & organelles
  • Nucleus
• Four major groups of biomolecules

  • Carbohydrates
  • Lipids
  • Proteins
  • Nucleotides and nucleic acids
• Carbohydrates

  • Chemical formula - (CH2O)n
  • Most abundant
  • Made of carbon, hydrogen, oxygen
  • Major sources of energy in the body
  • Simple - Monosaccharides (glucose, ribose)
  • Complex - Polysaccharides (glycogen, starch)
• Monosaccharides


  • Simple sugars
  • General formula is C6H12O6
  • Major monosaccharides are glucose, galactose and fructose
  • Produced by digestion of complex carbohydrates
  • Regulate blood sugar levels
• Disaccharides


  • Composed of 2 monosaccharides
  • Major disaccharides are sucrose (glucose + fructose), lactose (glucose + galactose), and maltose (glucose + glucose)
• Polysaccharides


  • Chains of glucose subunits
  • Starch - energy storage in plants, digestible by humans for energy
  • Cellulose - structural molecule of plant cell walls, fiber in our diet
  • Glycogen - energy storage in animals, liver synthesizes after a meal and breaks down between meals
• Lipids


  • Structurally diverse
  • Triglycerides / Neutral Fats - energy storage
  • Phospholipids - membranes
  • Steroids - membranes/hormones
  • Eicosanoids - signaling molecules
• Fatty Acids


  • Chain of 4 to 24 carbon atoms
  • Classified as saturated - carbon atoms saturated with hydrogen, or unsaturated - carbon atoms not saturated with hydrogen
• Monosaccharides


  Simple sugars, general formula C6H12O6, structural isomers, major monosaccharides are glucose, galactose and fructose, produced by digestion of complex carbohydrates, regulate glucose in blood sugar levels
• Disaccharides

  Composed of 2 monosaccharides, major disaccharides are sucrose (glucose + fructose), lactose (glucose + galactose), and maltose (glucose + glucose)
• Polysaccharides


  Chains of glucose subunits, include starch (energy storage in plants), cellulose (structural molecule of plant cell walls), and glycogen (energy storage in animals)
• Lipids


  • Contain carbon and hydrogen (little oxygen), structurally diverse including triglycerides/neutral fats, phospholipids, steroids, and eicosanoids
• Fatty Acids


  Chain of 4 to 24 carbon atoms, classified as saturated (carbon atoms saturated with hydrogen) or unsaturated (contains C=C bonds without hydrogen)
• Triglycerides (Neutral Fats)


  3 fatty acids bonded to glycerol molecule, liquid at room temperature (oils) often polyunsaturated from plants, solid at room temperature (fats) often saturated from animals, function as energy storage, insulation and shock absorption
• Steroids and Cholesterol


  Steroids are lipids with carbon atoms in four rings, all steroids are derived from cholesterol, include cortisol, progesterone, estrogens, testosterone and bile acids, cholesterol is an important component of cell membranes and produced only in animal liver cells
• Proteins


  Made of 20 amino acids with amino group (-NH2) and acid group (-COOH), have four levels of structure (primary through quaternary), include structural, storage, contractile, and transport proteins
• Nucleotides


  Composed of a base, sugar (carbohydrate), and phosphate groups, transmit and store genetic information in DNA and RNA, transmit and store energy in ATP, cAMP, NAD, and FAD
• Central Dogma of Genetic Information

  DNA → RNA → Protein
• Basis of phenotypic variation is genetic variance (35 million single-nucleotide substitutions, ~3% other structural variants) and epigenetic modifications of the genome during development
• Genes can be switched 'on' and 'off', different sets of genes are turned 'on' in different types of cells
• In some species of reptiles, sex is determined by the temperature at which the egg is incubated
• Nutrition can influence epigenetics
• Energy


  The ability to do work, including chemical, transport, and mechanical work in biological systems
• Kinetic energy


  Energy of motion (chemical, transport, mechanical)
• Potential energy


  Stored energy (concentration gradient, chemical bonds)