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
Hormone
chemical messenger secreted into bloodstream, stimulates response in another tissue or organ /// a chemical that is secreted from an endocrine gland/tissue/cell into the body fluids (typically the bloodstream) which has an effect on some target cell or effector.
Target cells
have receptors for hormone ///will respond to the hormone only if it has a receptor specific for that hormone (ie. insulin binds to insulin receptors). It is an analogous system to neurotransmitters and their specific receptors.
Endocrine glands
produce hormones
Endocrine system
endocrine organs (thyroid, pineal, etc) hormone producing cells in organs (brain, heart and small intestine)
True endocrine glands
- Pineal gland
- Thyroid gland
- Thymus gland
- Parathyroid gland
- Adrenal glands
- Pituitary Gland (Hypophysis)
Secondary endocrine structures
- Hypothalamus
- GI tract
- Heart
- Pancreas
- Ovaries
- Testes
- Placenta
- Liver
- kidney