Chapter 2

Question 0

What animal is used for the research of gene mutations?

Answer 0

Since the discovery of gene targeting in mice, mice has been used to research different effects of gene mutations.

Question 1

What animal is used for the research of Parkinson’s?

Answer 1

The rat brain has been used as the model for Parkinson’s research.

Question 2

What are the main parts of the brain?

Answer 2

Spinal cord
Brainstem
Cerebellum
Midbrain 
Thalamus
Hypothalamus
Pallidum
Striatum 
Cerebral cortex

Question 3

What are the three ventricles in early development found in the neural tube and their development?

Answer 3

The three swellings found in the neural tube are forebrain, midbrain and hindbrain vesicles.

The forebrain vesicle develops another pair of ventricles laterally known as the lateral ventricles. The cerebral cortex and the deep cerebral structures arises from the lateral ventricles. The rest of the forebrain vesicle forms the diencephalon(pretectum, thalamus and pre thalamus) and the hypothalamus.

The midbrain vesicle forms the midbrain and the four colliculus located in the dorsal side.

The hindbrain vesicle gives rise to the last part of the brain stem and the cerebellum.

Question 4

What are the sections of the diencephalon called, how many are there and what makes up each section?

Answer 4

The diencephalon is made up of three prosomeres. The first prosomere is the pretectum, the second prosomere is the thalamus and the third prosomere is the prethalamus. The hypothalamus was first included, but later excluded due to different gene signature.

Question 5

What is the diencephalon?

Answer 5

The diencephalon is one of the major subdivisions of the forebrain.

Question 6

What separates the right cerebral hemisphere from the left?

Answer 6

The longitudinal fissure.

Question 7

What is the rhinal fissure in humans?

Answer 7

Lateral fissure

Question 8

Why is the olfactory bulbs relatively small in humans compared to other mammals?

Answer 8

Almost all animals rely on the sense of smell to mark their habitats, find food, avoid prey and for navigations. This makes it an important sense and the olfactory bulb is relatively large. However in humans, these behaviours are not present and the reliance of smell is reduced, causing the olfactory bulb to be relatively small. Also, most mammals have an additional olfactory system to detect special social cues called pheromones, which is not present in humans.

Question 9

What are some of the functions of the midbrain?

Answer 9

The midbrain carries all ascending fibres. They have centres for auditory and visual processing, and for controlling basic movement patterns.

Question 10

Why is the cerebellum easily recognisable in cross sections?

Answer 10

They have many folds.

Question 11

What is the hindbrain otherwise known as?

Answer 11

Medulla oblongata.

Question 12

What are the functions of the hindbrain?

Answer 12

The hindbrain is a corridor for bundles of connections linking the brain and spinal cord, they also contain centres that control breathing, swallowing and state of consciousness.

Question 13

What happens when the hindbrain is damaged?

Answer 13

If it was shaken up, the person might lose consciousness for sometime. However if it was damaged, the person most often dies.

Question 14

Where does the optic chasm lie?

Answer 14

The optic chiasm lies in front of the hypothalamus.

Question 15

What forms the optic chiasm?

Answer 15

The optic chiasm is formed by the two optic nerves joining together for some fibres to crossover. It again splits to give rise to the optic TRACT.

Question 16

Where is the amygdala located?

Answer 16

The amygdala is the bulge behind the temporal lobe.

Question 17

What is the key feature that marks the position of the hypothalamus?

Answer 17

The key feature that marks the position of the hypothalamus is the pituitary stalk.

Question 18

Where is the mammillary bodies located?

Answer 18

The mammillary bodies are located behind the pituitary stalk.

Question 19

What carries the descending fibres and what is the gap between them?

Answer 19

The cerebral peduncles carries the descending fibres and the gap between the peduncles is the interpedunclar fossa. The area below is part of the midbrain.

Question 20

What part partially contains the cells that make up the hypothalamus?

Answer 20

Mammillary bodies.

Question 21

What is the connection between the superior and inferior olive?

Answer 21

Nothing, the inferior olive is a clock for the cerebellum and the superior olive processes auditory information.

Question 22

What are the main parts of the hindbrain?

Answer 22

The pons
The trapezoid body covering the superior olive
The facial nuclei
The inferior olive

Question 23

What are the three ways the brain can be viewed?

Answer 23

Coronal is parallel to your face
Sagittal is parallel to your ears
Horizontal is parallel to the horizon

Question 24

What are cranial nerves?

Answer 24

Cranial nerves are nerves that are connected to the brain and are connected to the sensory organs, muscles and glands in the head.

Question 25

What are the directional pair terms used in the brain language?

Answer 25

Anterior(facing the front) and posterior(facing the back)

Inferior(lower region in terms of height) and superior(higher in terms of height)

Ventral(front part) and dorsal(back part)

Rostral(top in terms of neural axis) and caudal(lowering terms of neural axis)

Question 26

How are neurons arranged?

Answer 26

Neurons that are arranged in clusters are called nucleus(the cell body) and tracts(the axons).

Neurons that are arranged in sheets are called areas.

Question 27

What are different terms for tracts?

Answer 27

Fasiculus, faniculus, and lemniscus(oval in horizontal cross sections)

Question 28

What is the difference between commissure and decussation?

Answer 28

Commissures are thick band of fibres which look like a single band but have fibres crossing over. Decussation is like a cross or a “X” where fibres crossover in the midline.

Question 29

Examples of commissures

Answer 29

Anterior commissure

Corpus callosum

Question 30

Examples of decussation

Answer 30

Optic chiasm

Pyramidal decussation

Question 31

How many segments of the spinal cord are there?

Answer 31

There are 31 total segments.

8 are cervical
12 are thoracic
5 are lumbar
5 are sacral 
1 is coccygeal

Question 32

How long is the spinal cord compared to the vertebral column?

Answer 32

2/3 of the vertebral column

Question 33

What are the enlarged portions of the spinal cord and why?

Answer 33

C5 to T1- upper limb
L2 to S2 - lower limb

This is due to the increased amount of motor neurons supplying the limb muscles

Question 34

What are spinal nerves?

Answer 34

Spinal nerves are pairs of nerve that arises from the spinal cord through the intervertebral foramina. They are made up of two roots- the dorsal(sensory) and ventral(motor) roots.

Question 35

What are spinal ganglion or dorsal root ganglion?

Answer 35

A swelling in the dorsal root that contains the cell bodies of thousand pseudo unipolar neurons whose axons bifurcates t reach the periphery and the other to reach the spinal cord.

Question 36

What is the neuropil?

Answer 36

The space between neuronal cell bodies.

Question 37

What are part of the grey matter in the spinal cord?

Answer 37

They contain neuronal cell bodies. They are divided into the ventral and dorsal horn, and the intermediate part.

Question 38

What are part of the white matter in the spinal cord?

Answer 38

They have longitudinally running tracts. They are divided into ventral, dorsal and lateral part. The dorsal part is split int two by the midline. The ventral part is split by two by the ventral median fissure. The distinction between is lateral and ventral is formed by an arbitrary line that starts from the most lateral motor neuron.

Question 39

What is the intermediolateral grey of the spinal cord?

Answer 39

A tiny extension of intermediate grey of the spinal cord in the thoracic, first two lumbar and sacral regions. The thoracic and lumbar intermediate grey contains the cell bodies of the preganglionic sympathetic cells and the sacral part contains the cell bodies of preganglionic parasympathetic cells.

Question 40

What is CSF?

Answer 40

Cerebrospinal fluid is a clear liquid that flows in the ventricles and between the meninges and acts as a shock absorber.

Question 41

What secretes CSF?

Answer 41

Cerebrospinal fluid is secreted by the choroid plexus, a special blood vessel system adjacent to the lateral ventricles.

Question 42

What is the flow of CSF?

Answer 42

Cerebrospinal fluid is secreted by the choroid plexus, which enters the lateral ventricles. It then flows downward into the third ventricle which is a narrow slit between the hypothalamus. It then flows through the aqueduct of the midbrain into the fourth ventricle. It flows into three holes in fourth ventricle between the layers of meninges. It is then re absorbed by veins close to the skull.

Question 43

What happens when CSF is impeded?

Answer 43

It causes the intercranial pressure to rise due to the accumulation of CSF in the particular area causing neurons to die.

In a prenatal condition called hydrocephalus, the ventricles expand and apply pressure or the cerebral cortex which kills the neurons.

Question 44

What are meninges?

Answer 44

Meninges are three layers of tissue that covers our brain and spinal cord. The dura mater is the outer most layer and is thick tissue. The pia mater is soft and cling, and is the innermost layer. These layers are connected weblike strands and this is the arachnoid mater. The CSF flows between the pia and arachnoid mater.

Question 45

What is the blood brain barrier?

Answer 45

The lining of the blood capillaries with the specialised membranes of the endothelial cells in the brain. This vascular arrangement tightly regulates the flow of molecules into the extra cellular fluid. These endothelial cells have fewer endocytotic vesicles compared to other endothelial cells, limiting the transcellular transportation. However, small lipid soluble molecules can pass through the membrane through passive diffusion. All drugs designed for the brain have to be lipophilic. Some of these unwanted molecules are removed by active transporters such as p-glycoprotein transporter protein is important in expelling these small lipid soluble molecules. There also tansporters like glut-1 transporter which helps in the transport of glucose into the ECF.

Question 46

How can the BBB fail?

Answer 46

During inflammatory processes, the permeability of the endothelial cell membranes changes. This can allow pathogens or toxins to enter the brain. These infections can be life threatening.

Question 47

What are circumventricular organs and give some examples?

Answer 47

Some parts of the brain that are supplied by blood capillaries without the BBB. They include the area postrema in the floor of the fourth ventricle, subfornical and vascular organ of the lamina terminalis in the walls of the third ventricles, the median eminence of the hypothalamus, the choroid plexus, the pineal gland, and the posterior lobe of the pituitary gland.

Question 48

What is still be argued of whether being a circumventricular organ?

Answer 48

Some researchers believe that the posterior pituitary lobe should not be included as the neural processes directly secretes oxytocin and vasopressin into the blood stream.