Download Exam 3 Review KEY

BIOL 255 SI, Molly
Exam 3 Review KEY, 10/24/16
Draw out a flow diagram of the Nervous System. Include all the subdivisions and
their characteristics. Hint: it can be found in 3A.
3A
1) The nervous system is made up of the Central Nervous System (CNS) which
contains the brain and the spinal cord and the Peripheral Nervous System (PNS)
which is all nerves outside of the brain and spinal cord.
2) Sensory neurons that bring information to the brain are referred to as
afferent, and Motor neurons that carry information away from the brain are
efferent.
3) The CNS neuroglia protects and supports. In the CNS astrocytes are star
shaped cells which attach neurons to blood vessels and form the blood brain
barrier, which controls the neuron environment.
4) In the CNS oligodendrocytes extend processes, to form myelin sheath.
5) In the Peripheral Nervous System (PNS) the schwann cells, also called
neurolemmocytes, form the myelin sheath, whereas, the satellite cells support
ganglia.
6) The smaller / bigger the size of the nerve fiber, the slower / faster the speed
of nerve impulse. And the less / more myelin, which means larger diameter of the
nerve fiber, the greater the speed.
7) Bundles of afferent and efferent neurons outside the CNS but inside the PNS
are referred to as nerves. While bundle of afferent and efferent neurons within
the CNS are referred to as tracts.
8) In the PNS the Schwann cells wrap around the axon and are referred to as the
neurilemma. Between adjacent neurilemmas are spaces made up of neurofibril
nodes and these nodes are referred to as the Nodes of Ranvier. The speed of the
stimulus increases as it jumps from node of ranvier to node of ranvier.
9) Multipolar neurons have several dendrites and one axon extended from the cell
body which is the most common type.
10) The bipolar neuron has one dendrite and one axon with the cell body in
between, these are rare and found only in specialized sense organs.
11) Most synapses, are chemical synapses in which the neurotransmitter is
secreted by the pre-synaptic cell which then diffuses across the synaptic cleft to
the post-synaptic cell. This occurs in a one way direction and is slower than the
action potential.
3B
12) Cerebrospinal fluid (CSF) is a watery, clear solution similar to blood plasma,
although it contains less protein and has different ions. Its function is to cushion,
gives buoyancy prevents delicate brain matter from being crushed, protects,
nourishes and carries chemical signals through it.
13) In Spinal Cord and Spinal Nerves the white matter is aggregations of
myelinated axons and myelin is white. While the gray matter is make up of cell
bodies or dendrites which is unmyelinated fibers.
14) In the spinal cord, the posterior white column or funiculus contains sensory
input which is received from the PNS to the brain, on tracts that ascend into the
brain bringing sensations of touch, pressure and body movement.
15) The anterior and lateral white columns or funiculi contain sensory input which
travel on ascending tracts to the thalamus, where sensory input is sorted, such as
pain and temperature, and the cerebellum where coordinate movements like walking
and motor output are sorted then the tracts descend to motor neurons which
eventually stimulate muscles.
16) So when you think about the spinal cord, everything towards the
front or anterior or ventral is associated with motor neurons or efferent neurons.
As where everything in the back or posterior or dorsal is associated with sensory
neurons or afferent neurons.
3C
17) The cerebral hemispheres function differently:
Left Hemisphere (in most)
Right Hemisphere (in most)
Right hand control (body)
Left hand control (body)
Language
Music & Art
Numeric & Scientific skill
Space & Pattern Perception
Reasoning
Insight
Comparing
18) The thalamus gland is the relay station for sensory input, except for smell, to
the cerebrum. Its role is in mediating sensation, motor activities, cortical arousal,
learning, and memory. It has four groups of nuclei on each side: anterior, ventral,
dorsal, and posterior.
3D
19) In the Autonomic Nervous System (ANS) motor neurons innervate the viscera
of smooth and cardiac muscle and also glands, as it regulates the viscera to ensure
homeostasis during body activities.
20) In the Autonomic Nervous System the neurotransmitters used are as follows:
Parasympathetic pre ganglionic neurons use - acetylcholine
Parasympathetic post ganglionic neurons use – acetylcholine
In the:
Sympathetic pre ganglionic neurons use – acetylcholine
But:
Sympathetic POST ganglionic neurons use – Norepinephrine.
21) In the developmental aspects of the PNS sensory receptors atrophy with age
and muscle tone lessens but peripheral nerves remain viable throughout life unless
subjected to trauma.
3E
22) Sensory receptors classed by location are the Proprioceptors which respond to
the degree of stretch of organs and are found in skeletal muscles, tendons, joints,
ligaments, and connective tissue coverings of bones and muscles and are constantly
“advising” the brain of one’s movements and body position.
23) Simple Receptors can be unencapsulated which have free dendritic nerve
endings and respond chiefly to temperature and pain such as Merkel discs and hair
follicle receptors. Encapsulated receptors are surrounded by tissue. Examples
would be Meissner’s and Pacinian corpuscles.
24) Endoneurium is the nerve covering around individual fibers. Fascicles are
groups of nerve fibers wrapped in perineurium and the epineurium is around entire
nerve.
3F
25) In the Olfactory Pathway, receptor cells synapse with olfactory bulb neurons,
which process odor signals and send them to the Olfactory cortex, the
Hypothalamus, the amygdala, and limbic system but totally bypass the Thalamus.
26) The tongue has three main papillae types: filiform, fungiform, and
circumvallate, but only the fungiform and circumvallate papillae contain taste buds.
27) In the sensory tunic of the retina the photoreceptors cells are made up of
rods which respond to dim light and are used for peripheral vision. Cones respond
to bright light and have high-acuity color vision and are found in the macula lutea
where they are concentrated in the fovea centralis, where no rods are found.
28) The cochlea is divided into three chambers:
– Scala vestibuli is connected to vestibule - ↑ and ↓ pressure in perilymph
-Scala media (cochlear duct) - ↑ and ↓ pressure in endolymph
- Scala tympani- ↑ and ↓ pressure in perilymph
29) Scala vestibuli connects to scala tympani at the helicotrema in the cochlea
where low pitch sounds are detected. High pitch sounds are detected near the oval
window.
30) Ceruminous glands in your external ear produce ear wax for waterproofing.