Download Nervous System Bookwork—KEY

Nervous System Bookwork—KEY
Ch 7: S/A # 6, 9, 12, 14 Clinic # 2, 5, 10
Short answer
6. A threshold stimulus causes a change in membrane permeability that allows Na +
to enter the neuron through sodium gates. This causes local depolarization and
generates the action potential, which is then self-propagating. This event is
quickly followed by a second permeability change that restricts Na + entry but
allows K+ to leave the neuron, causing repolarization. One way conduction
occurs at synapse because axons (not dendrites) release the neurotransmitter.
9. Check figure 7.13, p. 216 (the following is an example) http://www.narconon.ca/images/info_brain3.jpg
12. Bone: enclosed by the skull
Membranes: The meningeal membranes –dura mater, arachnoid, and pia
mater—enclose the brain within the skull and provide a passage for the
circulation of CSF and its return to the blood.
Fluid: Cerebrospinal fluid (CSF) cushions the brain from physical trauma.
Capillaries: The capillaries of the brain are permeable only to glucose, a few
amino acids, and respiratory gases. Hence, they protect the brain from
possibly harmful substances in the blood.
14. Major reflex center; pathway for ascending sensory impulses and descending
motor impulses.
Clinic:
2. Hypoglossal (XII)
5. Sternocleidomastoid and trapezius muscles
10. The nervous system is formed during the first month of development.
Chapter 8: S/A # 5, 9, 14, 21 Clinic #2, 3, 7
Short answer:
5. Vitreous humor: posterior to lens; reinforces eyeball
Aqueous humor: anterior to lens; reinforces eyeball and provides nutrients to
the avascular lens and cornea
9. Cornea to aqueous humor, through pupil to aqueous humor to lens to vitreous
humor to retina
14. As one ages, the lens loses its elasticity, causing it to focus less acutely for
close vision. Hyperopia.
21. Sensorineural deafness arises from damage to neural structures
(vestibulocochlear nerve or auditory cortex cells) due to stroke or other
trauma. Conductive deafness arises from any interference with the
conduction of vibrations from the outer to the inner ear due to ear wax
accumulations, otitis media, fusion of the ossicles, or pressure imbalance
between the middle and outer ear.
Clinic:
2. The children probably have conjunctivitis (pink eye), caused by bacteria or
viruses; it is highly contagious.
3. High intraocular pressure generally indicates that the patient has glaucoma.
7. Rods are very light sensitive photoreceptors used in dim light. Cones require
intense light. Focusing hard on the star focuses light on the fovea centralis which
only has cones, no rods. Perhaps the starlight is not strong enough to stimulate
the cones. Vision at night relies heavily on rods.