6A: Sensing the environment Flashcards Preview

MCAT > 6A: Sensing the environment > Flashcards

Flashcards in 6A: Sensing the environment Deck (79)
Loading flashcards...

What is a threshold?

The minimum amount of stimulus required to cause an action potential


What is the absolute threshold?

The minimum intensity of a stimulus that one can detect


What is the difference threshold?

The minimum difference in intensity between two stimuli that one can detect; also known as the just noticeable difference


What does Webers Law indicate?

There is a constant ratio between the change in stimulus to produce a difference threshold and the magnitude of the original stimulus;


What is Weber's constant/fraction?

1/5 or 2%


What is Signal Detection Theory?

It states that nonsensory factors can influence thresholds; it focuses on changes in our perception of the same stimuli depending on psychological and environmental context;

The ability to discern between stimuli and noise


What are the parts of a signal detection experiment?

Consists of catch trials (where stimuli is present) and noise trials (where stimuli are absent)


What are the outcomes of a signal detection experiment?

HIT = signal present and detected
MISS = signal present and not detected
FALSE ALARM = single absent and detected
CORRECT NEGATIVE/REJECTION = single absent and not detected


What is sensory adaptation?

It is the ability of our bodies to become accustomed to a stimulus after repeated application of the stimulus; both the physiological and psychological component get decreased


What does sensory adaptation allow us to do?

It allows us to differentiate meaningful information from the background; unable to feel clothing after getting dressed


What do sensory receptors do?

They respond to stimuli and trigger electrical signals


What are sensory pathways?

Sensory pathways are nerve endings or sensory cells that receive stimuli and carry the information through sensory ganglia and arrive at the CNS


What are Ganglia?

Ganglia are found outside of the CNS and they are group of neuron cell bodies


What are Projection Areas?

Projection areas are portions of the brain that analyze the sensory input


What are the major sensory receptors?

Hair cells, Photoreceptors, Thermoreceptors, Mechanoreceptors, Osmoreceptors, Nocireceptors, Olfactory receptors, Chemoreceptors


What do Hair cells detect?

Movement of fluid in the inner ear


What are simple receptors?

Neurons with free nerve endings


What are complex neural receptors?

Nerve endings that are enclosed in connective tissue capsules


What are special senses receptors

These are neurons that release neurotransmitter onto sensory neurons that initiate action potentials


Which lobe of the brain is devoted to vision?

Occipital lobe


How does the eye receive nutrients?

Choroidal and retinal vessels


What is the duplicity theory of vision?

This theory posits that the retina contains two kinds of photoreceptors which are specialized for light and dark detection


What is the function of Rods? What kind of pigment(s) do they contain?

It functions in reduced illumination and allow for sensation of light and dark; they have a low sensitivity to detail; pigment = rhodopsin


What is the function of Cones? What kind of pigment(s) do they contain? How does the Fovea relate to cones?

It functions in color detection and sensing of fine detail; contain S, M and L pigments; Fovea only has cones so its important in visual acuity and sensitivity to daylight vision


What is the function of amacrine & horizontal cells?

They receive input from many of the retinal cells before it is passed onto the ganglion cells; they focus the slight differences between the visual information in each cell increases the perception of stimuli


What are the two muscles of the iris and what do they do?

Dilator pupillae = opens the pupil under sympathetic stimulation
Constrictor pupillae = constricts pupil under parasympathetic stimulation


What is the Choroid and what is its function?

It is a continuous structure of the iris along with the ciliary body; it produces aqueous humor and washes the anterior chamber of the eye


Where is the lens of the eye located and what is its function?

It's located behind the iris and controls the refraction of entering light


What is the function of the ciliary muscle (part of the ciliary body)?

It contracts under parasympathetic stimulation to change the shape of the lens (known as accommodation)


What is the function of vitreous humor?

It's a transparent gel that supports the retina behind the lens