BIO365S Exam 1

• Two major approaches to physiology:

  • Teleological: focuses on why things happen
  • Mechanical: focuses on how things happen
• Transport across cell membrane:

  • Moves from HIGH concentration to LOW concentration (concentration gradient)
  • Moves on their OWN concentration gradient, no two different gradients can cancel each other out
  • Cell membrane is made of PHOSPHOLIPIDS
  • Some molecules can freely move across the membrane, such as cholesterol
• Functions of the cell membrane:

  1. Physical isolation

  2. Regulation of exchange with the environment

  3. Communication between the cell and the environment

  4. Support & structure
• Proteins perform most of the specific functions of the membrane
• Permeability across the membrane depends on:

  • Lipid solubility
  • Size
  • Charge (uncharged/nonpolar molecules can cross the membrane)
• Fick’s Law of Diffusion Across Membranes:

  Rate = surface area x concentration gradient x permeability / membrane thickness

  • Membrane thickness is inversely related to diffusion rate
• Carriers are similar to enzymes:

  • Catalyze transport process
  • Have specific substrates
  • Undergo conformational change
  • Affected by temperature, pH, etc.
  • Subject to competition and saturation
  • Have allosteric sites
• Secondary active transport:

  • Transporter protein couples the movement of an ion DOWN its concentration gradient with the movement of another molecule AGAINST its concentration gradient
• Osmolarity & Tonicity:

  • For a 70kg person, about 60% of its body is water
  • Plasma osmolarity is 290-300mOsM
  • Interstitial fluid is the main component of ECF
  • Osmolarity is the number of PARTICLES in a solution
  • Tonicity describes how the cell behaves in the solute
• Equilibrium conditions:

  • Distribution of water and penetrating particles is determined by the distribution of NON-PENETRATING particles
  • Tonicity deals with NON-PENETRATING PARTICLES
• Types of particles:

  1. Non-penetrating:

  • Completely non-penetrating: protein
  • Functionally non-penetrating: NaCl

  2. Penetrating:

  • Freely penetrating: urea
  • Slowly or partially penetrating: glucose
• Standard Intravenous Solutions:

  • Normal saline (0.9% NaCl): iso-osmotic
  • D5W: hypotonic
  • D5NS: hyper-osmotic
  • ½ NS: hypotonic
  • D5 ½ NS: hyper-osmotic
• Characteristics of receptors:

  • Exhibit saturation, specificity, and competition
  • Usually exist in families of related isoforms
  • Are down-regulated by decreasing receptor number
• Four classes of membrane receptors:

  1. Ligand-gated ion channel

  2. Receptor enzyme

  3. G protein-coupled receptor

  4. Integrin receptor
• Secondary messengers:

  • Initiate signal transduction
  • Examples: cAMP, cGMP, IP3, DAG
  • ACH has 5 different types of receptors
• Homeostasis:

  • Role of autonomic nervous system in maintaining normal levels
  • Tonic activity maintains a baseline that can be increased or decreased
  • Antagonistic control: one system increases while the other decreases
  • Effects of chemical signals vary based on receptors
• Examples of simple reflexes:

  • Simple Endocrine Reflex
  • Simple Neural Reflex
• Three major classes of hormones:

  1. Steroid

  2. Peptide

  3. Amine
• Hormonal interactions:

  1. Synergism

  2. Permissiveness

  3. Antagonism
• Hormones can be categorized by their interactions: synergism, permissiveness, and antagonism
• Hormones have opposing effects
• Hormones can be categorized by connection to the hypothalamus
• Posterior pituitary is an extension of the nervous system with a neural connection to the hypothalamus
• Examples of hormones from the posterior pituitary are oxytocin (milk let down reflex) and vasopressin (ADH; anti-diuretic hormone; tells kidney to reabsorb water back)
• Anterior pituitary is an endocrine gland from epithelial tissue with a vascular connection to the hypothalamus
• The anterior pituitary has a portal system where one capillary bed connects to another capillary bed (renal system, hypothalamus, GI tract)
• The pituitary gland is the “master gland” comprised of two parts
• Posterior pituitary is an extension of the hypothalamus, comprised of neural tissue, and releases neurohormones oxytocin and vasopressin
• Anterior pituitary is an outgrowth of the roof of the mouth, comprised of true endocrine/glandular tissue, and releases classic hormones
• Negative feedback is a critical aspect of endocrine reflexes
• Hormones need to be maintained; even a low level of hormones can do a lot to your body
• Trophic hormone has no other physiological function other than to trigger another hormone release
• Diagnosis of origin of pathology: primary pathology begins in the final endocrine gland (e.g., adrenal gland), secondary pathology begins in tissue producing trophic hormones (e.g., anterior pituitary or hypothalamus)
• Resting membrane potential = concentration gradient x membrane permeability (FOR EACH ION)
• Equilibrium Potentials: resting membrane potential is closest to equilibrium potential of potassium
• Small gap between neuron to neuron: synaptic cleft
• Voltage gated Ca2+ channel triggers neurotransmitter release
• Neurotransmitters follow principles of protein-based ligand action and can be excitatory or inhibitory
• Hippocampus and memory: responsible for processing long term memory and emotional response
• Transport across cell membrane:

  • Moves from HIGH concentration to LOW concentration (concentration gradient)
  • Moves on their OWN concentration gradient, no two different gradients can cancel each other out
  • Cell membrane made of PHOSPHOLIPIDS
  • Some molecules can freely move across membrane: cholesterol