The brain

Question 1

what is the cerebrum divided into

Answer 1

cerebrum is divided into two halves known as the cerebral hemispheres

The hemispheres are joined together by a band of nerve fibres known as the corpus callosum

Question 2

what is the thin outer layer of the cerebrum known as

Answer 2

the cerebral cortex

this consists of the cell bodies of neurones

It is highly folded, which increases its surface area and allows it to contain a greater number of neurones

With more neurones in the brain, more neurone connections can be made

greater the ability of the brain to carry out more complex behaviours

Question 3

what is beneath the cerebral cortex

Answer 3

‘white matter’

The white matter consists of the myelinated axons of neurones

Question 4

what does hypothalamus monitor

Answer 4

the blood as it flows through the brain and, in response, releases hormones or stimulates the neighbouring pituitary gland to release hormones

Question 5

4 functions of the hypothalamus

Answer 5

Regulating body temperature

Osmoregulation
Cells in the hypothalamus monitor the water balance of the blood and releases the hormone ADH if the blood becomes too concentrated

Regulating digestive activity

Controlling endocrine functions

Question 6

what does the cerebellum do

Answer 6

cerebellum coordinates movement

Question 7

what does medulla contain

Answer 7

co-ordination centres that control different functions

The cardiac centre controls heart rate
The respiratory centre controls breathing rate

Question 8

How does CT scan work

Answer 8

produce cross-section images of the brain using x-ray radiation

A beam of x-rays are aimed at a patient

Digital x-ray detectors are used to pick up the x-rays as they exit the patient’s body

Denser tissue absorbs more of the x-ray radiation so shows up as a lighter region on a scan

Question 9

What is CT scan good for

Answer 9

shows physical structures of the brain and allows visualisation of any tissue damage

blood is less dense than brain tissue so a CT scan can be used to locate damaged blood vessels and areas of bleeding after a patient has had a stroke

Question 10

who is CT scan not recommended for

Answer 10

pregnant patients or children due to the risks of exposure to the X-ray radiation, which is given at a higher level than in a normal X-ray

Question 11

How does MRI work

Answer 11

a combination of a magnetic field and radio waves to generate images through the body

Question 12

what can be seen using MRI

Answer 12

Soft tissues
identify and locate tumours in the brain

Question 13

MRI vs CT

Answer 13

MRI scans are considerably more expensive to carry out than CT scans

but do not carry the risk associated with the use of potentially harmful x-rays

Question 14

difference between fMRI and MRI

Answer 14

fMRI scans allow brain function to be studied in real time

Question 15

how does fMRI show which brain region is active

Answer 15

location of oxygenated blood indicates
which brain regions is active

Question 16

what does fMRI scanner measure

Answer 16

measures the ratio of oxygenated to deoxygenated haemoglobin

Question 17

what does PET scan use

Answer 17

radioactive tracers which collect in areas where there is increased blood flow

Question 18

what is the visual cortex

Answer 18

region of the cerebral cortex in which visual information is processed

Question 19

what is the cerebral cortex

Answer 19

the outer layer of the cerebrum

Question 20

what is a critical period

Answer 20

stages in the lifespan of an organism where it is particularly sensitive to a specific stimulus which is required for the organism to develop properly.

Question 21

what is habituation

Answer 21

If a stimulus is repeated many times with no negative outcome, then an animal will learn not to respond to it

Question 22

what happens due to habituation

Answer 22

fewer calcium ions move into the presynaptic neurone on arrival of a nerve impulse

As a result, less neurotransmitter is released and an action potential is less likely to be generated in the postsynaptic neurone

Question 23

what is Parkinsons disease

Answer 23

a brain disorder that affects the co-ordination of movement, caused by the loss of neurones in some parts of the brain

Question 24

what do the lost neurones in parkinsons disease normally produce

Answer 24

neurotransmitter dopamine

Dopamine is involved in muscle control
Individuals that suffer from Parkinson’s disease produce insufficient amounts of dopamine due to the loss of dopamine-producing neurones

Question 25

what happens when less dopamine is released into synaptic cleft

Answer 25

less is able to bind with receptors on the postsynaptic membrane

Fewer sodium channels on the membrane are opened so depolarisation of the postsynaptic neurone does not occur

This leads to fewer action potentials which creates the symptoms such as tremors and slow movement

Question 26

types of drugs that treat parkinsons

Answer 26

Dopamine precursors - L dopa
These are chemicals that can be converted into dopamine in the neurones

Dopamine agonists
Produce the same effect as dopamine by binding to and activating the dopamine receptors on the postsynaptic membrane

Enzyme inhibitors
Monoamine oxidase B (MAOB) inhibitors inhibit the activity of enzymes that would normally break down dopamine in the synaptic cleft, raising levels of dopamine present in the brain

Question 27

what is linked to depression

Answer 27

Low levels of the neurotransmitter serotonin

Question 28

what does serotonin do

Answer 28

transmits nerve impulses through the areas of the brain that control mood

Question 29

what does MDMA do

Answer 29

inhibits the reuptake of serotonin into the presynaptic neurone by binding to the specific proteins that enable serotonin reuptake, located on the presynaptic membrane; this increases the amount of serotonin present in the brain

Serotonin is usually reabsorbed into the presynaptic neurone to be recycled for future action potentials

MDMA also triggers the release of further serotonin from presynaptic neurones, further adding to the increase

Question 30

what does a person who takes MDMA / ecstasy feel

Answer 30

extreme euphoria and enhanced touch and bodily sensations

Question 31

where is L dopa transported from and what is it converted to

Answer 31

transported from the blood into the brain, where it is converted into dopamine in a reaction catalysed by the enzyme dopa-decarboxylase

Question 32

what does L Dopa do

Answer 32

increase levels of dopamine so that more nerve impulses are transmitted in parts of the brain that control movement, giving sufferers better control over their movement and lessening the symptoms of Parkinson’s disease

Question 33

What does Human genome project involve

Answer 33

sequencing of the entire human genome

The information gained during the HGP is stored in databases, within which genes that code for certain proteins can be found and analysed

Knowing the sequence and structure of proteins involved in disease allows the development of drugs that target specific proteins

Question 34

what does genetic engineering consist of

Answer 34

removing a gene that codes for a desired characteristic from one organism and transferring the gene into another organism where the desired gene is then expressed

Question 35

what does the genetically engineered organism contain

Answer 35

recombinant DNA and will be a genetically modified organism (GMO)

Question 36

what removes gene coding for desired protein

Answer 36

Restriction enzymes

Question 37

what are the copies of the gene made by PCR inserted into

Answer 37

small loops of DNA called plasmids, which then transfer the copies into micro-organisms
The plasmids are said to be DNA vectors
The enzyme DNA ligase catalyses the joining of the desired gene to the plasmid vector

Question 38

where are the genetically modified micro organisms grown

Answer 38

in large fermenters containing nutrients, enabling them to multiply and produce large quantities of the new protein

The protein can be isolated and purified before being packaged and distributed

Question 39

how can animals be genetically modified

Answer 39

gene that codes for the desired protein is injected into the nucleus of a zygote

The zygote is implanted into the uterus of a surrogate animal where it develops into an adult animal