DRAFT: This module has unpublished changes.

 

 SMELL

     http://www.medicalook.com/human_anatomy/organs/Olfactory_sense.html

 

 

What is smell?

 

Smell is the ability for a person to detect odors or scents by the means of either directly smeliing something using the nose or by the means of chewing food and the odor travels to the back of the nose. The sense of smell is important because it helps to detect any warning odors such as a gas leak. The sense of smell and taste work together but a fould odor is the first sign that possibly the food you are about to eat is not good. 

 

We can smell everything around us because of the olfactory receptors located in the the olfactory epithelium found on the nasal cavity. The olfactory epithelium consists of three cells;

  • sensory neurons- contains primary cilium
  • supporting cells
  • basal cell- produce sensory neurons by dividing regularly

http://www.britannica.com/EBchecked/media/48235/The-olfactory-epithelium-found-within-the-nasal-cavity-contains-olfactory

 

 What is the mechanism of smell?

 

The reason that humans are able to differentiate odors it is because once smell is sensed in the olfactory bulb it passes signals up to the brain and areas that are associated with memory. 

  • The olfactory epithelium has a layer of mucus that contains cilia and the odor molecules ravel to this location and dissolve withing the mucus. 
  • They bind to the receptors in the cilia and activates the G- protein coupled to the recpetor in the cytoplasmic side
  • The enzyme adenyl cyclase is activated which catalyzes ATP to cyclic AMP in the cytosol
  • cAMP opens ligand gated Na+ ion channels for facilitated diffusion of sodium ions into the cell 
  • The influx of Na+ causes a reduction in the potential across th plasma membrane
  • Once the threshold is reached the action potential is generated
  • An action potential will be conducted from the back along the olfactory nerve to the brain
  • The brain receives these olfactory signals as specific odors.

What disorder is associated with the sense of smell?

 

Anosmia is the complete or partial loss of smell due to several factors. Anosmia can be caused by an extreme case of sinus infections, head trauma to the frontal lobe where smell is controlled, Parkinson's or Alzheimer's disease, and epilepsy among others. 

 

 

 

  

DRAFT: This module has unpublished changes.

The a brief summary of the mechanism behind smell.

DRAFT: This module has unpublished changes.