keeps blood vessels in continual state of partial constriction
controls blood pressure even at rest
vascular system is almost entirely innervated by sympathetic fibers
sympathetic fibers fire ______ to _______ blood vessels and cause blood pressure to rise
sympathetic fibers fire ______ to _______ blood vessels and cause a decrease in blood pressure
more rapidly
constrict
more slowly
dilate
the parasympathetic division _______ _______ heart activity
normally dominates
parasympathetic = _____ and _____
rest and digest
the overall boss on ANS activities is the __________
hypothalamus
another name for the parasympathetic nervous system
craniosacral region
(long ganglions)
3 primary colors
blue green and red
the colour of light that an object __________ determines the colour the eye perceives
reflects
define refraction
bending of light rays
pathway of light entering the eye
cornea
aqueous humor
lens
vitreous humor
entire neural layer of retina
photoreceptors
the _________ of the eye is basically responsible for the refraction of light
cornea
far point of vision
distance beyond which no change in lens shape is needed for focusing
20 feet (6 m) for emmetropic eye
ciliary muscles are relaxed
distance object; lens is __________
flat
focusing for close vision requires these three steps:
accommodation of the lens: (condition = presbyopia, loss of accommodation)changes shape of the lens to increase refraction, but there is a near point of vision
constriction of the pupil: reflex constricts pupils to prevent most divergent light rays rom entering the eyes
convergence of eyeballs: medial rotation of the eyeballs toward the object being viewed
close vision involves ___________ activation; while distance vision involves ________ activation