1
Problem 1
BRAIN AND BODY
The body uses two systems to communicate: the nervous system and the endocrine (hormonal) system.
The nervous system is composed of 2 division:
The central nervous system (CNS) is the division of the nervous system located within the skull and spine.
It is composed of two divisions: the brain and the spinal cord. The brain is located in the skull and the spinal
cord in the spine.
The peripheral nervous system (PNS) is the division of the nervous system located outside the skull and
spine. It is composed of two divisions:
1. The somatic nervous system (SNS) and
2. The automatic nervous system (ANS).
The somatic nervous system interacts with the external environment, controls voluntary muscles, and convey
sensory information to the CNS. It is conscious and composed of:
The afferent nerves which carry sensory signals (From sense to brain) from skin, skeleton muscles, joint,
eyes, ears and so on to the central nervous system. It brings information into a structure.
The efferent nerves carry motor signals (From brain to muscles) from the central nervous system to the
skeletal muscles. It sends away information from the structure.
The automatic nervous system regulates the body’s internal environment, controls involuntary muscles. It is
unconscious and it is composed of:
-The afferent nerves that carry sensory signals from internal organs to the central nervous system.
-The efferent nerves that carry motor signals from the central nervous system to the internal organs. There are
two kinds of efferent nerves in the automatic nervous system: sympathetic and parasympathetic nerves
The sympathetic nerves are automatic motor nerves that project from the CNS in the lumbar (small of the
back) and thoracic (chest area) regions of the spinal cord. It expends energy and stimulates arousal.
The parasympathetic nerves are automatic motor nerves that project from the brain and sacral (lower
back) region of the spinal cord. It conserves energy, inhibits arousal, and stimulates relaxation.
Both sympathetic and parasympathetic nerves have a two-stage paths: the neurons project from the CNS and
go only in part of the way to the target neurons before they synapse on other neurons (second stage neuron)
that carry out the signals the rest of the way
The difference between them it is that the sympathetic neurons project from the CNS on a second-stage
neurons at a substantial distance, instead the parasympathetic neurons project from the CNS synapse near
their target.
THREE MENINGES
The brain and spinal cord (the CNS) are the most protected organs in the body. They are covered by three
protective membranes, the three meninges.
1. The outer meninx is a tough membrane called dura mater
2. The next membrane is the arachnoid membrane (spider-web-like membrane)
,2
Below it, there is a space called subarachnoid space, which contains many large blood vessels and
cerebrospinal fluid.
3. The pia mater adheres to the surface of the CNS
The central nervous system is protected by the cerebrospinal fluid, that can be found in the subarachnoid
space, the central canal of the spinal cord, and the cerebral ventricles of the brain.
There are all interconnected by a series of openings and thus form a single reservoir.
Occasionally, the flow of cerebrospinal fluid is blocked by a tumor near one of the narrow channels that
link the ventricles
As a result, the buildup of fluid causes the walls of the ventricles and the entire brain to expand, producing
a condition called hydrocephalus (water head)
o This is treated by training the excess fluid from the ventricles and trying to remove the obstruction
The cells in the brain are packed and act as a barrier to any protein of large molecules. (Blood-barrier
barrier)
NERVOUS SYSTEM
Most of the cells of the Nervous System are essentially summed in two different types: neurons and glial cells
Neurons
Neurons are cells specialized in reception, conduction, and transmission of electrochemical signals to other
cells (neurons, gland, muscle cells) External autonomy of neurons consist in:
Neurons cell membrane
The neurons cell membrane is the semipermeable membrane that enclosed the neuron. It is composed of a
lipid bilayer, or two layers of fat molecules.
In the lipid bilayer there are many protein molecules that are the basis of many of the cell membrane’s
functional properties.
Some membrane proteins are channel proteins through which some molecules can pass through, others are
signal proteins, which transfer a signal to the inside of the neuron.
Dendrites the short processes emanating from the cell body, which receive most of the synaptic contacts
from other neurons.
Cell body the metabolic center of the neuron, also called soma.
Axon hillock the cone-shaped region at the junction between the axon and the cell body.
Axon the long, narrow process that projects from the cell body.
Myelin the fatty insulation around many axons.
Nodes of Ranvier the gaps between section of myelin.
Buttons the buttonlike endings of the axon branches, which release chemicals into synapses.
Synapses the gap between adjacent neurons where chemical signals are transmitted.
, 3
Classes of neurons
There are different types of neurons based on the number of processes emanating from their cell bodies.
Multipolar neuron = A neuron with more than two processes extending from its cell body.
Unipolar neuron = A neuron with one process extending from its cell body.
Bipolar neuron = A neuron with two processes extending from its cell body.
Interneurons = Neurons with short axon or no axon with the function of integrate neural activity within a
single brain structure rather than transmit a signal.
There are two kinds of neural structures in the nervous system: those composed mainly of cell bodies and
those composed mainly by axons
In the CNS, clusters of cell bodies are called nuclei. Bundles of axons are instead tracts
In the peripheral nervous system, clusters of cell bodies are called ganglia. Bundles of axons are called
nerves
The spinal cord
The spinal cord is made of two parts: the gray matter and the white matter.
The gray matter is largely composed by cell bodies and unmyelinated interneurons.
The white matter is rather composed of myelinated axons (myelin that gives the white sheen).
Many neurons from the gray matter of the spinal cord, send axons to the brain or to other parts of the spinal
cord through the white matter
Five major dimensions of the brain
In the vertebrate embryo, the first indication of the developing brain are three swellings that eventually
develop into the adult forebrain, midbrain, and hindbrain.
Before birth, the three initial swellings become five. (The forebrain and the hindbrain swellings grow into
two different swellings)
In humans and other vertebrates, the telencephalon undergoes the greatest growth during development.
The other division of the brain in individual structures consist in cerebrum (telencephalon), midbrain
(diencephalon, mesencephalon, metencephalon only with pons and myelencephalon) and cerebellum
(metencephalon)
1. Telencephalon
2. Diencephalon
3. Mesencephalon (or midbrain)
4. Metencephalon (medulla)
5. Myelencephalon
1. Hindbrain: myelencephalon and metencephalon
Problem 1
BRAIN AND BODY
The body uses two systems to communicate: the nervous system and the endocrine (hormonal) system.
The nervous system is composed of 2 division:
The central nervous system (CNS) is the division of the nervous system located within the skull and spine.
It is composed of two divisions: the brain and the spinal cord. The brain is located in the skull and the spinal
cord in the spine.
The peripheral nervous system (PNS) is the division of the nervous system located outside the skull and
spine. It is composed of two divisions:
1. The somatic nervous system (SNS) and
2. The automatic nervous system (ANS).
The somatic nervous system interacts with the external environment, controls voluntary muscles, and convey
sensory information to the CNS. It is conscious and composed of:
The afferent nerves which carry sensory signals (From sense to brain) from skin, skeleton muscles, joint,
eyes, ears and so on to the central nervous system. It brings information into a structure.
The efferent nerves carry motor signals (From brain to muscles) from the central nervous system to the
skeletal muscles. It sends away information from the structure.
The automatic nervous system regulates the body’s internal environment, controls involuntary muscles. It is
unconscious and it is composed of:
-The afferent nerves that carry sensory signals from internal organs to the central nervous system.
-The efferent nerves that carry motor signals from the central nervous system to the internal organs. There are
two kinds of efferent nerves in the automatic nervous system: sympathetic and parasympathetic nerves
The sympathetic nerves are automatic motor nerves that project from the CNS in the lumbar (small of the
back) and thoracic (chest area) regions of the spinal cord. It expends energy and stimulates arousal.
The parasympathetic nerves are automatic motor nerves that project from the brain and sacral (lower
back) region of the spinal cord. It conserves energy, inhibits arousal, and stimulates relaxation.
Both sympathetic and parasympathetic nerves have a two-stage paths: the neurons project from the CNS and
go only in part of the way to the target neurons before they synapse on other neurons (second stage neuron)
that carry out the signals the rest of the way
The difference between them it is that the sympathetic neurons project from the CNS on a second-stage
neurons at a substantial distance, instead the parasympathetic neurons project from the CNS synapse near
their target.
THREE MENINGES
The brain and spinal cord (the CNS) are the most protected organs in the body. They are covered by three
protective membranes, the three meninges.
1. The outer meninx is a tough membrane called dura mater
2. The next membrane is the arachnoid membrane (spider-web-like membrane)
,2
Below it, there is a space called subarachnoid space, which contains many large blood vessels and
cerebrospinal fluid.
3. The pia mater adheres to the surface of the CNS
The central nervous system is protected by the cerebrospinal fluid, that can be found in the subarachnoid
space, the central canal of the spinal cord, and the cerebral ventricles of the brain.
There are all interconnected by a series of openings and thus form a single reservoir.
Occasionally, the flow of cerebrospinal fluid is blocked by a tumor near one of the narrow channels that
link the ventricles
As a result, the buildup of fluid causes the walls of the ventricles and the entire brain to expand, producing
a condition called hydrocephalus (water head)
o This is treated by training the excess fluid from the ventricles and trying to remove the obstruction
The cells in the brain are packed and act as a barrier to any protein of large molecules. (Blood-barrier
barrier)
NERVOUS SYSTEM
Most of the cells of the Nervous System are essentially summed in two different types: neurons and glial cells
Neurons
Neurons are cells specialized in reception, conduction, and transmission of electrochemical signals to other
cells (neurons, gland, muscle cells) External autonomy of neurons consist in:
Neurons cell membrane
The neurons cell membrane is the semipermeable membrane that enclosed the neuron. It is composed of a
lipid bilayer, or two layers of fat molecules.
In the lipid bilayer there are many protein molecules that are the basis of many of the cell membrane’s
functional properties.
Some membrane proteins are channel proteins through which some molecules can pass through, others are
signal proteins, which transfer a signal to the inside of the neuron.
Dendrites the short processes emanating from the cell body, which receive most of the synaptic contacts
from other neurons.
Cell body the metabolic center of the neuron, also called soma.
Axon hillock the cone-shaped region at the junction between the axon and the cell body.
Axon the long, narrow process that projects from the cell body.
Myelin the fatty insulation around many axons.
Nodes of Ranvier the gaps between section of myelin.
Buttons the buttonlike endings of the axon branches, which release chemicals into synapses.
Synapses the gap between adjacent neurons where chemical signals are transmitted.
, 3
Classes of neurons
There are different types of neurons based on the number of processes emanating from their cell bodies.
Multipolar neuron = A neuron with more than two processes extending from its cell body.
Unipolar neuron = A neuron with one process extending from its cell body.
Bipolar neuron = A neuron with two processes extending from its cell body.
Interneurons = Neurons with short axon or no axon with the function of integrate neural activity within a
single brain structure rather than transmit a signal.
There are two kinds of neural structures in the nervous system: those composed mainly of cell bodies and
those composed mainly by axons
In the CNS, clusters of cell bodies are called nuclei. Bundles of axons are instead tracts
In the peripheral nervous system, clusters of cell bodies are called ganglia. Bundles of axons are called
nerves
The spinal cord
The spinal cord is made of two parts: the gray matter and the white matter.
The gray matter is largely composed by cell bodies and unmyelinated interneurons.
The white matter is rather composed of myelinated axons (myelin that gives the white sheen).
Many neurons from the gray matter of the spinal cord, send axons to the brain or to other parts of the spinal
cord through the white matter
Five major dimensions of the brain
In the vertebrate embryo, the first indication of the developing brain are three swellings that eventually
develop into the adult forebrain, midbrain, and hindbrain.
Before birth, the three initial swellings become five. (The forebrain and the hindbrain swellings grow into
two different swellings)
In humans and other vertebrates, the telencephalon undergoes the greatest growth during development.
The other division of the brain in individual structures consist in cerebrum (telencephalon), midbrain
(diencephalon, mesencephalon, metencephalon only with pons and myelencephalon) and cerebellum
(metencephalon)
1. Telencephalon
2. Diencephalon
3. Mesencephalon (or midbrain)
4. Metencephalon (medulla)
5. Myelencephalon
1. Hindbrain: myelencephalon and metencephalon
