Here is a complete and detailed summary of the 8 problems for the 1.4 block. It includes pictures and graphs that make it easier to understand! There is also a shorter summary which includes ONLY the important points of the 8 problems (is shorter of course) and it also includes pictures and graphs!
Complete summary
PROBLEM 1
What is the structure and function of neurons?
Sensory neurons are the ones that capture the information of the environment, while motor neurons
control the movements of muscles. The interneurons are between the sensory and motor neurons. The
most important cells of the nervous system are neurons and glial cells:
Neurons processes and transmit the information to the nervous system. The general external structure
of the neurons consists of:
Soma or cell body: contains the nucleus and provides life to the cell
Dendrites: pass the messages from neuron to neuron in the form of synapse (junction of
terminal buttons and dendrites).
Axon: carries information from the cell body to the terminal buttons and it´s often covered by
myelin sheath. The basic message it carries is called an action potential.
Terminal buttons: their function consists of when the action potential reaches them, they
produce a chemical called neurotransmitter that either excites or inhibits the receiving cell.
Thus, it helps to determine whether an action potential occurs in its axon.
,The three principal types of neurons (classified according to the way in which their axons and dendrites
leave the soma) are:
Multipolar neuron: This is the most common type of neuron. It has more than two processes
extending from its cell body.
Bipolar neuron: gives rise to one axon and one dendritic tree, at opposite ends of the soma.
Thus, it is both ways. They are usually sensory since the dendrites detect events occurring in the
environment and communicate information about this events to the central nervous system. It
has two processes extending from its cell body.
Unipolar neuron: it has branches in both ends. One in the beginning (dendrites) and two
branches (terminal buttons) at the end. They also transmit sensory information from the
environment to the CNS. It has one process extending from its cell body.
Supporting cells protect neurons since they have no means of storing nutrients and must constantly be
supplied with nutrients and oxygen so they don’t die. Two kinds: glia for the central nervous system and
schwann cells in the peripheral nervous system.
The Blood-brain barrier is a barrier that exist between the blood and the fluid that surrounds the cells
of the brain. It is selectively permeable because some substances can cross the barrier while others
cannot. However, in some areas, like the postrema area which controls vomiting, is permeable. The
function of the barrier is to regulate the composition of the fluid for the transmission of messages from
place to place in the brain. If the fluid levels are not good then the transmission is disrupted.
What is the structure and function of the nervous system?
There are some terms to locate and describe the nervous system. Neurexis is an imaginary line drawn
though the center of the length of the central nervous system, from the bottom of the spinal cord to the
front of the forebrain. The part of the nervous system that is located near or toward the head is called
anterior or rostral. The part that is located near or towards the tail/feet is called posterior or caudal. The
front part of the neurexis toward the stomach is called dorsal and the back part of the neurexis toward
the back is called ventral. Lateral is toward the side, while medial is toward the middle. Contralateral
refers to structures on opposite sides of the body, while ipsilateral refers to the structure on the same
side of the body. For example, ipsilateral is when the part is only in one hemisphere and contralateral
when it is in both.
We can slice the nervous system in three ways:
1. Frontal section: like salami giving us cross
sections.
2. Parallel to the ground, giving us horizontal
sections
3. Perpendicular to the ground and parallel to
the neuraxis giving us sagittal sections. The
midsagitall plane divides the brain into two
symmetrical halves.
, The nervous system consist of two basic divisions:
Central nervous system: consist of the brain and spinal cord
o Brain: explained below
o Spinal cord: its principal function is to distribute motor fibers to organs of the body and
to collect sensory information to be passes on to the brain. It also controls various
reflexive control circuits. It is protected by the vertebral column. It consists of two
different areas an inner core of gray matter (cell bodies and unmyelinated
interneurons) and a surrounding area of white matter (myelinated axons). Two dorsal
arms of the spinal gray matter are called dorsal horns, and the two vental arms are
called ventral horns. Pairs of spinal nerves are attached to the spinal cord. All dorsal
root axons, whether somatic or automatic, are sensory (afferent) unipolar neurons with
their cell bodies grouped together just outside the cord to from the dorsal root ganglia.
In contrast, the neurons of the ventral root are motor (efferent) multipolar neurons
with their cell bodies in the ventral horns.
Peripheral nervous system: found outside the bones and consists of the nerves and most of the
sensory organs. Its composed of two divisions:
a) Somatic nervous system: It interacts with the external environment. The brain and
spinal cord communicate with the rest of the body via the cranial nerves and spinal
nerves. Thus:
Spinal nerves: the nerves leave the vertebral column and travel to the muscles
or sensory receptors they innervate. The cell bodies of all axons are called
afferent axons because they bring sensory information into the brain and
spinal cord. In contrast, the axons that leave the spinal cord though the ventral
roots control muscles and glands are efferent axons.
Cranial nerves: serve sensory and motor functions of the head and neck region.
One of them, the vagus nerve, regulates the actions of organs in the thoracic
and abdominal activities.
b) Autonomic nervous system: regulates the body´s internal environment so it is
concerned with regulation of smooth muscle, cardiac muscle, and glands. It consists of
two anatomically separate systems or two kinds of efferent nerves
Sympathetic division: involved in activities associated with expenditure of
energy from reserves that are stored in the body. It also controls the adrenal
medulla
Parasympathetic division: supports activities that are involved with increases
in the body´s supply of
stored energy such as
salivation and secretion
of digestive juices.
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