‘Using made of the Cerebellum, Pons and Medulla

‘Using a
relevant example explain the importance of structure in relation to function in
biology’

 

This essay will
be highlighting some of the structures located in the brain and how the
specific structure aids in the function of the brain.

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Some facts about
the brain include that it contains roughly 86 billion nerve cells, which is
often referred to as ‘grey matter’. As well as that, the brain weighs about
1.5kg; which accounts for roughly 2 percent of a human body weight.

The definition
of the brain which is quoted from the dictionary is; “an organ of soft nervous tissue contained in
the skull of vertebrates, functioning as the coordinating centre of sensation
and intellectual and nervous activity”.

 

The Brain is
made up of three main parts: The forebrain, midbrain and hindbrain. The
Forebrain consists of the Cerebrum, Thalamus and Hypothalamus (which is part of
the Limbic system). The limbic system is found buried with the Cerebrum,
containing the Thalamus, hypothalamus, amygdala and hippocampus. The Midbrain
consists of the Tectum and Tegmentum, and the Hindbrain is made of the
Cerebellum, Pons and Medulla oblongata.

Focusing on the
Cerebellum, it is located at the base of the skull and is composed of white
matter and a thin outer layer of densely folded grey matter. Furthermore, the
Cerebellum contains hundreds of millions of neurones, this relates to the
function as the neurons enable the processing of data to allow for the many
functions of the cerebellum, one being movement coordination.

In addition to that, the Cerebellum can
be subdivided into three lobs, these include; the Anterior Lobe, Posterior Lobe
and the Flocculonodular lobe. This is vital to the function of the cerebellum
as the different pathways for various information allows for efficient
transmission of neural information allowing for fine motor control, producing
desired movements.

 

 

 

 

 

 

 

 

 

 

 

In Order to understand and comprehend the importance of the structure
relating to the function, you have to analyse situations where the structure is
altered affecting the function of the system. In relation to the Cerebellum,
damage to the nerve cells in the cerebellum results in a condition called
ataxia; this condition involves the loss of muscle control and coordination of
movement.

The causes of this include; Toxins such as Alcohol or heavy metal
poisioning, it could also be due to a faulty gene( hereditary ataxia).

In order for the ataxia to be diagnosed, there are a series of tests that
can be run in order to determine if any brain damage has occurred and the
significance of the brain damage,

These include; An MRI OR CT Scan which is used to examine the relative
density of the tissue surronding the brain, highlighting if any brain damage
has occurred and the region in which it has occurred. As well as that, Genetic
tests are run to diagnose ataxia as It can also be hereditary.

If the patient is Diagnosed with ataxia, there are ways In which to treat
the ataxia, these include; Speech therapy: which helps with swallowing,
coughing, choking and speech problems, Medication such as gamma-globulin
injections to boost the patients immune system, and many others.

This figure shows how Doctors use MRI Scans to diagnose Ataxia as it shows
a shrinkage in the Cerebellum(normal size on the right, ataxia(atrophy) on the
left:

 

 

Another example
which shows how structure relates to the function In the brain is the Hypothalamus
which is directly linked to the Pituitary gland. The Hypothalamus is located in
a region directly above the brainstem, it has a cone shaped structure that
projects downward from the brain, ending in a pituitary stalk, which is a
tubular connection that links the Hypothalamus and pituitary gland. This is
important as the Hypothalamus receives neural signals from the brain and
peripheral nervous system, the stalk allows for this information to be funnelled
to the pituitary gland which controls the bodies hormonal response and other Endocrine
responses.

Focusing more
on the Pituitary gland, its structure is composed of two main lobes; the
Anterior pituitary and Posterior pituitary. These two lobes regulate the
release of hormones across the body and have a widespread effect on the
behaviour of the body. For example, the Posterior pituitary results in the
release of oxytocin which is vital for the survival of a baby, this is because
the chemical results in the uncoupling of the mitochondria; changing its
primary function from ATP production to heat production, meaning the baby is
able to maintain its body temperature in colder environmental temperatures.

Reverting back
to the Hypothalamus, The collection of nuclei within the hypothalamus allows
for the efficient transmission and receiving of neural information from the
brain, allowing the Hypothalamus to undergo a variety of functions. One of the
important roles of the Hypothalamus is Homeostasis. Homeostasis is the
maintenance of equilibrium of a system such as the body, allowing for optimal
biological function by ensuring things such as body temperature, blood pressure
is kept at a constant level.

One of the ways
the Hypothalamus does this is through its connections to the autonomic nervous
system. This allows for the Hypothalamus to send signals to influence factors
such as heart rate, digestion, perspiration and other factors. An example of
when this could be stimulated is when the Hypothalamus detects that body
temperature is above the set point, Neural signals would be transmitted to
sweat glands to cause perspiration; resulting in a loss of heat via
evaporation.

 

To Appreciate
and understand the vast complexity of the structure of the Hypothalamus and how
it is pivotal to the function, it is crucial to analyse the disorders and
diseases associated with what happens if the structure is altered. An example
of this is Hypothalamic dysfunction, which is diagnosed when it is detected
that the hypothalamus is not carrying out its important role, e.g. releasing
the correct hormones. The causes of this disorder include; surgery, traumatic
brain injury, radiation and tumours. If the patient is diagnosed with
Hypothalamic dysfunction, common symptoms in children include growth problems;
either too much or too little or in other children puberty occurs to early or
too late, both caused by the missing of important hormones which would usually
be secreted by the pituitary gland. A Genetic type of this condition, called
Kallmann syndrome results in the patient having a lowered function of sexual
hormones, or in some cases the patient is unable to smell.

 

In order for
this disease to be diagnosed, Doctors need to perform a series of exams and
tests to be sure that the patient has the disease. The main tests that are done
is by performing a blood test or getting a sample of urine to determine the
level of hormones such as: Cortisol, Estrogen, Growth hormone, Pituitary
hormones, Prolactin, Testosterone, thyroid and many others. Which hormones are
examined is determined on a patient to patient basis. As well as that, other
tests include Hormone injections followed by timed blood samples MRI or CT
scans of the brain.

Once the
patient has been diagnosed, there is a set of treatment options that are
offered depending on the site of damage and the type of condition that is
present. Examples of these include; For tumours, surgery or radiation may be
required whereas in the case of hormonal deficiencies, missing hormones may
need to be artificially injected into the

patient.

 

 

 

A Third example
of how structure is directly linked to the function of an area in the brain is
the Medulla oblongata. The Medulla oblongata is the lowest part of the
brainstem found below the pons and above the spinal cord, research has shown
that there is no clear distinction between the medulla and the spinal cord, but
it is thought that the spinal cord transitions into the medulla.

 

One of the main
functions of the Medulla is the regulation of cardiovascular and respiratory
functions, this occurs when baroreceptors which are located in blood vessels
detect a change in blood pressure, this information is transmitted along
neurones to the nucleus of the solitary tract which stimulates a response that
returns the blood pressure to a desired rate. This relates to the function as
the location of the nucleus in the solitary tract allows for the processing of
the information from the baroreceptors, allowing for an adequate response to
take place.

As well as
that, the Medulla also controls reflexive actions such as swallowing, breathing
and coughing. This can take place as the inferior olivary nuclei which are
located in the lower sub section of the medulla, are connected to the
cerebellum and therefore allows for the transmission of neural information
allowing for movement to occur, further highlighting how the structure allows
for the function to occur.

 

 

 

To conclude,
the various examples that have been presented clearly show how the level of
complexity present in the various structures enables that part of the brain to
undergo its specific and very vital function, and how a defect or change in the
structure has a detrimental effect on the function and therefore the whole
system. 

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