graded potentials

Examples of graded potentials in the following topics:

• Postsynaptic Potentials and Their Integration at the Synapse

  • Postsynaptic potentials are excitatory or inhibitory changes in the graded membrane potential in the postsynaptic terminal of a chemical synapse.
  • Postsynaptic potentials are changes in the membrane potential of the postsynaptic terminal of a chemical synapse.
  • Postsynaptic potentials are graded potentials and should not be confused with action potentials, although their function is to initiate or inhibit action potentials.
  • This is an excitatory postsynaptic potential (EPSP) as it brings the neuron's potential closer to its firing threshold (about -50mV).
  • This is an inhibitory postsynaptic potential (IPSP).

• Membrane Potentials as Signals

  • In neurons, a sufficiently large depolarization can evoke an action potential in which the membrane potential changes rapidly.
  • Membrane potential (also transmembrane potential or membrane voltage) is the difference in electrical potential between the interior and the exterior of a biological cell.
  • The membrane potential has two basic functions.
  • The changes in membrane potential can be small or larger (graded potentials) depending on how many ion channels are activated and what type they are.
  • The action potential is a clear example of how changes in membrane potential can act as a signal.

• Types of Neurotransmitters by Function

  • Release of neurotransmitters usually follows arrival of an action potential at the synapse, but may also follow a graded electrical potential.
  • The most prevalent transmitter in the human brain is glutamate, which promotes excitatory effects by  increasing the probability that the target cell will fire an action potential.

• The Synapse

  • Release of neurotransmitters usually follows arrival of an action potential at the synapse, but may also follow graded electrical potentials found in dendrites.

• Types of Shock

  • Hypovolemic shock is the most common type of shock and is caused by an insufficient circulating volume, typically from haemoeehage although severe vomiting and diarrhea are also potential causes.
  • Hypovolemic shock is graded on a 4 point scale depending on the severity of symptoms and level of blood loss.

• Cervical Cancer

  • Cancer screening using the Pap smear can identify precancerous and potentially precancerous changes in cervical cells and tissue.
  • Treatment of high-grade changes can prevent the development of cancer in many victims.

• Prostate Disorders

  • The common prostate disorders are: prostatitis, benign prostatic hyperplasia, high-grade intraepithelial neoplasia, and prostate cancer.
  • The most common prostate disorders are: prostatitis, benign prostatic hyperplasia, high-grade intraepithelial neoplasia, and prostate cancer.
  • High-grade prostatic intraepithelial neoplasia, abbreviated HGPIN, is an abnormality of prostatic glands and believed to precede the development of prostate adenocarcinoma (the most common form of prostate cancer).
  • Other symptoms can potentially develop during later stages of the disease.

• Pulled Hamstring and Charley Horse

  • Grade 2 - With a grade two hamstring strain there is immediate pain which is more severe than the pain of a grade one injury.
  • Grade 3 - Bruising due to strained hamstring, horizontal lines show where bandage was.
  • A grade three hamstring strain is a severe injury.
  • Lower grade strains can easily become worse if the hamstring is not rested properly.
  • Grade one hamstrings should be rested from sporting activity for approximately three weeks, and grade two injuries typically require four to six weeks for recovery.

• The Action Potential and Propagation

  • Action potential is a brief reversal of membrane potential where the membrane potential changes from -70mV to +30mV.
  • When the membrane potential of the axon hillock of a neuron reaches threshold, a rapid change in membrane potential occurs in the form of an action potential.
  • This moving change in membrane potential has three phases.
  • Schematic and B. actual action potential recordings.
  • The action potential is a clear example of how changes in membrane potential can act as a signal.

• Resting Membrane Potentials

  • The potential difference in a resting neuron is called the resting membrane potential.
  • The potential difference in a resting neuron is called the resting membrane potential.
  • The resting membrane potential exists only across the membrane.
  • The Goldman formula essentially expresses the membrane potential as an average of the reversal potentials for the individual ion types, weighted by permeability.
  • Consequently, the resting potential is usually close to the potassium reversal potential.