BIO 141 Flashcards
Receptors:
structure specialized to detect a stimulus
Sense Organs:
nerve endings combined with connective, epithelial, or muscular tissues that respond to a stimulus
General flow of sensory information:
Receptor - sensory neuron - CNS thalamus - sensory cortex perception of the sensation
Labeled-line principle:
based on the fact that each nerve fiber to the brain leads from a receptor that specifically recognizes a particular stimulus type. (Ex: optic nerve)
phasic receptor -
burst of activity and quickly adapt (smell and hair receptors)
tonic receptor -
adapt slowly, generate impulses continually (proprioceptor)
- Adaptation:
a sensory receptors stops firing or adjusts its sensitivity during a prolonged stimulus
By origin of stimuli
interoceptors -
detect internal stimuli
proprioceptors - sense body position and movements
By origin of stimuli
exteroceptors -
detect external stimuli
Chemical Senses: Gustation (taste):
a sensation resulting from the action of chemicals on the taste buds in the mouth
Lingual papillae:
bumps on the surface of the tongue, most of which contain taste buds on their sides
Taste (gustatory) cells:
receptor cells with single microvilli that projects thru a taste pore and interfaces with the chemical in the saliva; modified epithelial cells with lifespan of 7-10 days
Basal cells:
give rise to taste cells
Support cells:
provide structure to the taste bud
- Sweet
- Salty
- Sour
- Bitter
- Umami (taste of amino acids (MSG))
- concentrated on tip
- lateral margins
- lateral margins
- posterior
Olfaction (smell):
a sensation resulting from odorant molecules acting on receptors
in the nasal epithelium of the nose.
Olfactory cells
- olfactory hairs neurons with 20 cilia bind odor molecules in thin layer of mucus axons pass through cribriform plate survive 60 days - Supporting cells - Basal cells
Physiology of Smell
- Molecules bind to receptor on olfactory hair
= hydrophilic - diffuse through mucus
= hydrophobic - transport by odorant-binding protein - Activate G protein and cAMP system
- Opens ion channels for Na+ or Ca2+
= creates a receptor potential
Action potential travels to brain - Receptors adapt quickly
= due to synaptic inhibition in olfactory bulbs