material english

8/12/2019 material english

1/8

2/21/11 3:.3.4

Page ttp://exploration21.com/2.3/2.3/2.3.4.html

Base 2.3 2.3.1 2.3.2 2.3.3 2.3.4 2.3.5 2.3.6 2.3.7 Wiki

Welcome to SECTOR 2.3.4

Scientific Principle 2.3.4: Structure and Function of the Brain: Effect

of Injuries

In Sectors 2.3.1and 2.3.2you learned about some functions and structures of the brain. You

also learned about the pupil reflex and blood pressure and their connection to the brain. In

Lab 2.3.3 you had the opportunity to check each others pupil reflex and blood pressure.

Today in class you should be ready to share your analysis of your results from Lab 2.3.3.

As you discuss your lab, consider the following points:

As you read through Scientific Principle 2.3.4pay close attention to the bold terms. You may

In Class Today: Lab 2.3.3. Analysis and DiscussionIn Sectors 2.2.1 and 2.2.2 you learned about velocity and acceleration. In Lab 2.2.3 you

observed different types of motion on position-time and velocity-time graphs. Today in class

you should be ready to share your analysis of your results from Lab 2.2.3. As you discuss

your lab, consider the following points:

1.How did your pupils respond to bright light? Was the response the same if light was shined

into the right versus left eye?

2.How did you pupils respond to less light? Was the response the same if light was shined

into the right versus left eye?

3.Did all students have same blood pressure? What might account for any similarities or

differences?

4.Would you consider the blood pressure and pulse pressure of the students normal? High?

Low? Why?

5.How do Nikkis pupil response and blood pressure compare with yours?

6.Do you think Nikkis collision with the other player cause any damage to her brain? Explain

why using her medical record and your data from Lab 2.3.3.

TREPANNING - Early humans performed medical interventions know as trepanning, in which a hole was drilled or scrapped

through the skull to remove foreign material and blood clots resulting from head injury. This specimen is a girls skull from the

neolithic period (3,500 BC). Judging from the bone growth at the intervention site, the patient survived. Click on photo forlarger image. (Source: Natural History Museum, Lausanne)

Sector 2.3.4

Nikkis Brain

Student Website
http://exploration21.com/2.3/2.3/Wiki.htmlhttp://exploration21.com/2.3/2.3/2.3.7.htmlhttp://exploration21.com/2.3/2.3/2.3.6.htmlhttp://exploration21.com/2.3/2.3/2.3.5.htmlhttp://exploration21.com/2.3/2.3/2.3.4.htmlhttp://exploration21.com/2.3/2.3/2.3.3.htmlhttp://exploration21.com/2.3/2.3/2.3.2.htmlhttp://exploration21.com/2.3/2.3/2.3.1.htmlhttp://exploration21.com/2.3/2.3/Base_2.3.html


2/8

2/21/11 3:.3.4


want to create a list of these terms in your science journal so that you can formulate

definitions and application examples as you read.

The Brains Importance

You probably would agree that the brain is a very important organ. From what you learned in

the Information Processing Sectorat the beginning of the year and from what youve read in

Scientific Principle 2.3.2,you should realize that almost every function of our bodies involves

some level of control by the brain. This includes functions like thinking, decision-making,

eyesight, sensation, pupil constriction and dilation, and control of heart rate, respiration, andblood pressure.

It shouldnt surprise you then, that damage to the brain may have many effects on the body.

Just what those effects are and how long it takes the brain and body to heal depends on how

much damage and in many cases, where the damage occurred in the brain.

Assessing Damage to the Brain

Imagine that you think you have broken a bone. You go to the emergency room or your

doctors office. What do they do? Take an X-ray. From the X-ray, it is usually pretty easy to

see if there is damage to the bone.

Determining if there is damage to the brain is, unfortunately, not that easy. Currently, there is

not one simple test that can determine if the brain has been damaged and where the damage

has occurred. Instead, physicians use many different tests including ones that you have

already seen (sideline assessment, pupil response, blood pressure) to determine whether

damage has occurred. Some of these tests include things like the sideline assessment where

different functions of the brain are tested by asking a person questions that test their memory

and orientation. Often these tests are referred to as cognitive tests. In the emergency room

or a physicians office, the physician will measure vital signs like blood pressure and heart

rate to test essential functions of the brain. He or she will also likely test a patients reflexes,

test whether they can move different parts of their bodies, feel sensations in different parts of

their bodies, or perform additional cognitive tests. In each of these cases, the physician is

testing a certain function that is controlled by certain structures of the brain. If there is a

change in the function, then it may mean there is damage to those structures in the brain.

Lets take a look at some examples of structures and functions of the brain that you should

remember from the Information Processing Sector.

Review of Structures/Functions of the Brain

Do you remember that each cerebral hemisphere can be divided into four different sections

called lobes?

Temporal lobe

Occipital lobe

Frontal lobe

Scientists continue to learn more about each of the

lobes, including their functions. Some of the currently

known functions of each of the lobes are described

below.

Parietal lobe: This area is in charge of integrating

information from the each of the senses. It is also

involved in our spatial orientation. In other words, it helps us understand, know or feel the

Parietal lobe


3/8

2/21/11 3:.3.4


parts of our bodies. Are our arms up or down? Are our legs raised?

Temporal lobe: Functions of this lobe include hearing, memory and emotions.

Occipital lobe: This area is responsible for vision.

Frontal lobe: The frontal lobe is responsible for cognition (thinking), control of behavior, and

emotion.

If we further divide the lobes, we can see that certain

areas of each of these lobes are responsible for

different functions.

There are areas of the brain in the parietaland frontal

lobes that are responsible for sensory (senses) and

motor (movement) functions.

Somatosensory cortex: This area is responsible for the perception of touch from surface of

body. It is found in the parietal lobe.

Primary motor cortex: This area is responsible for sending information from brain to spinal

cord for voluntary control of muscular movement. It is in the frontal lobe.

Premotor cortex: This area is responsible for the planning of movement. It is in front of

primary motor cortex in frontal lobe.

There are areas of the brain in the occipital, parietal and temporal lobes that are responsible

for vision, hearing, and language.

Primary visual cortex: This area is

responsible for the perception of vision. It

receives input from eyes and is the back-

most part of occipital lobe. The

surrounding areas of occipital lobe are

concerned with analysis of vision.

Primary auditory cortex: This area

receives input from ears. It is the upper surface of temporal lobe. Both ears go to both sides

of brain.

Motor speech: Broca's area is the lower region of frontal lobe on left side only. Damage to

this area results in the inability to produce meaningful language. Speech is affected.

Sensory speech: Wernicke's area is the region of temporal and parietal lobe on left side

only. Damage to this area results in the inability to understand language.

If we stop at take a look at what weve learned so far, we see that there is a left and rightparietal lobe, a left and right temporal lobe, a left and right frontal lob, and a left and right

occipital lobe. These lobes are contained within the left and right hemispheres of the

cerebrum.

In general, the RIGHT side of the BODY is controlled by lobes on the LEFT side of the

BRAIN.

The LEFT side of the BODY is controlled by lobes on the RIGHT side of the BRAIN.


4/8

2/21/11 3:.3.4


There are some areas such as Brocas and Wernickes areas that are located only on one

side of the brain and control an overall function such as speech or language comprehension.

Going Deeper into the brain

But what makes up the brain? How is information within the brain stored? How does

information from the brain get to other parts of the body? The answer, as you would guess,

can be complicated.

However, we can simplify the answer if we say that the brain is mainly made up of cells

called neurons. Hopefully, you remember that cells are the smallest units in the body

capable of supporting life, and that cells can perform certain functions. As it turns out, the

body is made up of different types of cells. Neurons are a type of cell found in the brain, in the

spinal cord, and as part of nerves.

The basic function of a neuron is to receive, send, and in some cases, store information.

Neurons do this through chemicals and electrical current. They have special structures that

help them with this function. The diagram below shows what scientists call a typical neuron.

The dendrites are the part of

the neuron that generally

receive electrical and chemical

signals from other neurons.

The information contained in the signals passes from the dendrites through the cell body to

the axon.

The axonis a long process that extends outward from the cell body. Electrical signals pass

along the length of the axon to its ends called axon terminals.

When the electrical signal reaches the axon terminals, chemicals (neurotransmitters) are

released. These chemicals can travel across the small space between neurons called a

synapseto another neuron.

The diagram below shows how electrochemical signals (electrical + chemical) are passed

between neurons.

In simple terms, the cell body

of a neuron is the part that

contains the nucleus. Within the

nucleus are RNA and DNA -

genetic molecules that contain

information and instructions for

the operation and function of

the neuron.


5/8

2/21/11 3:.3.4


Much of what you see when you view the brain is the arrangement of neuron upon neuron

upon neuron. Estimates of how many neurons are in the brain vary as scientists still struggle

with ways to count these cells. One estimate suggests that the human brain contains 100

billion neurons and 100 trillion synapses! In Lab 2.3.5you will have the opportunity to view a

slide of neurons from the cerebellar cortex.

Looking inside the head and brain

In addition to cognitive tests, when physician think that the impact of a collision may have

caused a more severe concussion or head trauma, he/she may order a test called a CT scan

(X-ray Computed Tomography). You may often hear this type of test referred to as a cat

scan.

The picture to the

right shows a

patient inside a CT

scanner and the

images that appear

on the imaging

computer. CT scans

can be used to

image many

different parts of the

body, including the

head.

The image below shows a series of sections of a patients head and brain from a CT scan.

This type of test allows the physician to see inside a patients head and brain without

performing surgery. During a CT scan, many X-rays are taken of the patients head from

different angles. A computer puts these X-rays together in order to give a more three-

dimensional view of the head and brain.


6/8

2/21/11 3:.3.4


The images that you see on a CT scan are based on the ability of X-rays to penetrate

different structures of the head and brain. Differences in the ability of the X-rays to penetrate

result in different colors on the CT scan. Structures that are MORE DENSE, like bone, do

not allow X-rays to pass through as easily as structures that are LESS DENSE, like cerebral

spinal fluid. MORE DENSE structures appear brighter (more white) on a CT scan. LESS

DENSE structures appear darker.

There are several things a physician may look for when viewing the CT scan of a patient that

has had a concussion. Two items are listed below.

1.Is there bleeding inside the skull? Is there bleeding inside the brain?

Bleeding inside the skull or in the brain is obviously not a very good thing. The head is a

closed compartment. This means that if there is bleeding in the skull or in the brain, the bloodgenerally has no way to get out of the skull or brain. Instead, it tends to collect and build up.

This increases the pressure on the brain. The increased pressure on the brain can squeeze

brain tissue, causing damage.

The increased pressure can also squeeze the arteries on the outer surface of the brain that

supply the brain with blood and oxygen. If this happens, then less and less blood and oxygen

get to the brain. A decrease in blood and oxygen to the brain can cause the neurons in the

brain to die.

One type of injury that causes bleeding into the skull is called

a subdural hematoma. A subdural hematoma is bleeding

between the inside of the skull and brain. It will appear

WHITE on a CT scan. The arrow on the CT scan shows asubdural hematoma that is pushing the brain to the right side

of the skull (notice that left and right are reversed in CT

scans).


7/8

2/21/11 3:.3.4


Take a look at a section of Nikkis medical record below. What was the ER physicians

diagnosis? Did she have a subdural hematoma as a result of the impact?

2.How is the brain sitting in the skull? Is it in a normal position? Or has it shifted to one side

or another because of increased pressure on the brain? What areas may be affected by the

increased pressure?

By looking at where a subdural hematoma or other injury has occurred, the physician can see

which areas of the brain may not be functioning correctly. Many times, it is not only the area

of the brain where the injury is, but also areas of the brain that have been squeezed by the

increase in pressure that are not working properly. For example, if the occipital lobe is under

pressure, then the patient may be experiencing problems with his or her vision even thoughthat is not the area of the head to which the impact occurred.

Multiple Concussions

One of the most fatal mistakes that can be made with concussions is not allowing the brain to

heal before returning to normal activities. Some research shows that people who have

suffered ONE concussion are four to six times more likelyto suffer another concussion during

an impact. And if a second concussion occurs BEFORE the brain has completely healed, the

damage from the second concussion is GREATER. This is called Second Impact Syndrome

and although it is rare, it is more likely to occur in high school athletes. Second Impact

Syndrome has a mortality rate of 50%, showing just how deadly this injury can be.

How long does it take for the brain to heal from a concussion? There is no one answer. It

depends on how much damage occurred to the brain. It may take several weeks, several

months, or even a year. Working with a physician is important when recovering from a

concussion because he or she can help determine when the brain has healed and when it is

safe to return to play.

Take a look at a section

of Nikkis medical record

to the right. Was this her

first or second

concussion? Do you

think she had healed

from her first

concussion?

Homework 2.2.4: Problems Involving the Brain and Its Functions

In Lab 2.3.5 your group will view a slide of neurons in the cerebellar cortex with the

microscope and digital camera. You will also view Nikkis CT scan to determine the location ofher subdural hematoma. Using a sheep brain and model of a human brain, you will predict


8/8

2/21/11 3:.3.4


Copyright 2011 Cognitive Learning Systems

what where the damage to Nikkis brain occurred.

On the Student Wiki site, you will find your homework problems.

material english

Documents

Transcript of material english