2. anatomy
The shape and size of the brains of different species vary greatly, and identifying common features is often
difficult. However ,Some aspects of brain structure are common to almost the entire range of animal species;
others distinguish "advanced" brains from more primitive ones, or distinguish vertebrates from invertebrates.
The simplest way to gain information about brain anatomy is by visual inspection. Visually ,the areas of the
brain consist in grey matter and white matter.
Grey matter :
Grey matter contains most of the brain's neuronal cell bodies. The grey matter includes regions of the brain
involved in muscle control and sensory perception such as seeing and hearing, memory, emotions, speech,
decision making, and self-control. While 20% of all oxygen taken in by the body goes to the brain, 95% of that
goes specifically into the grey matter. It consists of neuronal cell bodies, glial cells (which are non-neuronal
cells that provide support and protection for neurons in the brain) and capillaries( which are the smallest of a
body's blood vessels and parts of its microcirculation).
White matter :
consists mostly of glial cells that transmit signals from one region of the cerebrum to another and between the
cerebrum and lower brain centers. White matter actively affects how the brain learns and functions. While
grey matter is primarily associated with processing and cognition, white matter modulates the distribution of
action potentials, acting as a relay and coordinating communication between different brain regions. White
matter is the tissue through which messages pass between different areas of gray matter within the nervous
system. The brain in general can adapt to white-matter damage by finding alternative routes that bypass the
damaged white-matter areas White matter makes up parts of the brain and spinal cord and facilitates
communication between gray matter and the rest of the body.

3. Celular structureThe brains of all species are composed primarily of two broad classes of cells: neurons and glial cells. Glial cells come in
several types, and perform a number of critical functions, including structural support, metabolic support and guidance of
development. Neurons, however, are usually considered the most important cells in the brain. The property that makes
neurons unique is their ability to send signals to specific target cells over long distances. They send these signals by means
of an axon, which is a thin protoplasmic fiber that extends from the cell body and projects, usually with numerous
branches, to other areas, sometimes nearby, sometimes in distant parts of the brain or body. The length of an axon can be
extraordinary. Most of the space in the brain is taken up by axons, which are often bundled together in what are
called nerve fiber tracts.
These axons transmit signals in the form of electrochemical pulses called action potentials, which last less than a
thousandth of a second and travel along the axon .Some neurons emit action potentials constantly, at rates of 10–100 per
second, usually in irregular patterns; other neurons are quiet most of the time, but occasionally emit a burst of action
potentials. Axons transmit signals to other neurons by means of specialized unions called synapses. When an action
potential, traveling along an axon, arrives at a synapse, it causes a chemical called a neurotransmitter to be released(are the
brain chemicals that communicate information throughout our brain and body). The neurotransmitter attaches
to receptor molecules in the membrane of the target cell. It is widely believed that activity-dependent modification of
synapses (they can strength or weaken over time)is the brain's primary mechanism for learning and memory.

4. Parts of the brain(lobes)
The brain is divided into four sections, known as lobes .The frontal lobe, occipital lobe, parietal lobe, and temporal lobe
have different locations and functions that support the responses and actions of the human body.
Frontal lobe: is the emotional control center of the brain responsible for forming our personality and influencing out
decisions. The frontal lobe is located at the front of the central sulcus where it receives information signals from other
lobes of the brain.it has many functions ,most of which center on regulating social behavior, for example it is related with
cognition, problem solving ,reasoning, motor skill development ,parts of speech, regulating emotions, planning ,etc.
Parietal lobe: processes sensory information for cognitive purposes and helps coordinate spatial relations so we can make
sense of the world around us.it has several functions ,such as sensing pain, pressure and touch, regulating and processing
the body´s five senses, movement and visual orientation, speech,cognition and information processing, etc.
Temporal lobe: is the location of the primary auditory cortex. It has many functions ,such as the formation of visual and
verbal memories, interpretation of smells and sounds and it helps to form long term memories and process new
information.
Occipital lobe :.the smallest of the four lobes and it is the primary visual processing center of the brain. Some of the
functions include:
Visual and spatial processing and movement and color recognition

5. Brain components
The medulla: contains many small nuclei involved in sensory and motor functions.
The pons: lies above the medulla and control sleep, respiration ,swallowing, equilibrium, eye movement,
posture, facial expressions ,etc.
Hypothalamus: its a small region. It is composed of numerous small nuclei ,each with different
connections and neurochemistry.it regulates sleep ,eating and drinking, hormone release ,etc.
Thalamus: It has diverse functions , Some are involved in relaying information to and from the cerebral
hemispheres and Others are involved in motivation.
Cerebellum: it modulates the outposts of other brain systems to make them precise.
The midbrain: it is associated with vision ,hearing, motor control, temperature regulation; etc.
The spinal cord( brainstem) : it plays a role in conduction.it is important in cardiovascular system
control, respiratory control, pain, awareness, consciousness, etc.