Unit 2

Question 1

What are some protective and support structures of the CNS? (x3)

Answer 1

The cranium, the meninges and the cerebrospinal fluid

Question 2

What are the three layers of the meninges?

Answer 2

The outermost layer is the dura mater, middle is the arachnoid mater and the innermost layer is the pia mater

Question 3

What is the second largest structure in the brain after development?

Answer 3

The cerebellum

Question 4

When is there the most brain development during gestation? When does brain folding occur?

Answer 4

Most development occurs in the end of the first trimester. The folding of the cerebrum occurs way later, just before birth

Question 5

In what layer of the meninges are there blood vessels? What occurs if there is a break in one of these arteries? Why is this so dangerous?

Answer 5

There are blood vessels in the arachnoid mater. If there is a break here there is a “brain bleed/hematoma/subdural hematoma”. This is so dangerous because in this section of the brain, there is point of exit and the blood stays within the arachnoid space and there is an increase in ICP

Question 6

What is the choroid plexus? What types of cells are these?

Answer 6

These are the cells within each ventricles that secrete CSF. They are a type of glial cells within the brain

Question 7

What is indicative of blood cells or elevated proteins in the CSF (via lumbar puncture sampling of fluid in the subarachnoid space)? How does it do this?

Answer 7

Suggests infection. You can see this as the sample will be cloudy or there is blood

Question 8

What are the glial cells in the CNS? What are their functions?

Answer 8

Oligodendrocytes (form myelin sheath within the CNS), Microglia (innumerable cells), Astrocytes (regulate ECF) Ependymal Cells (barrier cells within compartments, epidermal derivation)

Question 9

How is CSF reabsorbed back into the venous blood?

Answer 9

Via Arachnoid villi

Question 10

What is the circulation of CSF?

Answer 10

Lateral ventricles > Third ventricles > fourth ventricle . subarachnoid space . arachnoid villi > superior/dural sagittal sinus > venous return

Question 11

What are the cells that create a barrier around the capillaries in the brain? They secrete what type of factor? What does this do?

Answer 11

Astrocytes put out foot processes that encircle the capillaries. They secrete paracrine factor that on the endothelial cells of the capillaries that control the permeability of the vessel by promoting tight junction formation.

Question 12

What types of molecules can and cannot cross the BBB?

Answer 12

Lipid soluble molecules cross readily (ethanol). Hydrophilic substances will only cross if there are the proper transporters present. Hydrophobic molecules have trouble crossing.

Question 13

What type of cell (oxygen requirement) are neurons? How does oxygen cross the BBB?

Answer 13

They are obligate aerobes. Oxygen crosses the barrier readily

Question 14

How much of the body’s glucose does the brain need?

Answer 14

The brain is responsible for about 50% of the body’s glucose consumption.

Question 15

What are the divisions of the spinal cord?

Answer 15

The four divisions are the cervical (neck), thoracic, lumbar and sacral.

Question 16

What. is the most important parasympathetic nerve? Why? what organs does it innervate? (x6)

Answer 16

The vagus nerve. It innervates almost all the organs and sphincters of the abdomen. It innervates the lungs, liver, gall bladder, small intestine, large intestine and the pancreas.

Question 17

Where do parasympathetic preganglionic fibres arise from? What about sympathetic?

Answer 17

Parasympathetic > cranio-sacral

Sympathetic > thoraco-lumbar

Question 18

What is a nerve, ganglion, tract and nuclei?

Answer 18

Nerve > A bundle of axons in the PNS
Ganglion > A cluster of cell bodies in the PNS
Tract > A bundle of axons in the CNS
Nuclei > A cluster of cell bodies in the CNS

Question 19

What type of information does the dorsal root of the spinal cord carry versus the ventral root?

Answer 19

The dorsal root carries information in (the afferent sensory information) while the ventral root carries information out ( the efferent motor information) to the effector.

Question 20

What is the dorsal root ganglion?

Answer 20

The bundle of cell bodies of the afferent sensory nerves coming in. It is a ganglion because it is within the PNS?

Question 21

What differentiates the CNS vs. the PNS?

Answer 21

Anything that is outside of the brain or the spinal cord is considered the PNS.

Question 22

What is the difference between white and grey matter?

Answer 22

Whit matter is the outer portion of the spinal cord and is made of the myelinated axons carrying information - it is the “through lanes”. The grey matter is where integration occurs and where the synapses occur - it contains cell bodies and dendrites.

Question 23

What region of the dorsal horn grey matter integrate somatic sensory information? Visceral sensory? Autonomic sensory?

Answer 23

Somatic is in the most dorsal portion of the dorsal horn. Visceral is just slightly further in. And the autonomic is the most central/ventral.

Question 24

Why is there no such thing as a central root ganglion?

Answer 24

This is because the cell bodies of the somatic motor neurons are within the ventral horn grey matter.

Question 25

What are the ascending and descending tracts of the brain?

Answer 25

Ascending tracts - dorsal columns and the spinal thalamic

Descending tracts - lateral and ventral corticospinal tracts

Question 26

What is a “spinal reflex”?

Answer 26

A reflex tat does not involve sending information to the brain

Question 27

What structures make up the brain stem?

Answer 27

The pons, medulla and midbrain

Question 28

What is the function of the midbrain? The pons? The medulla? What “section” of the brain are the medulla and pons a part of?

Answer 28

The midbrain is coordination of eye movement, and visual and auditory reflexes. The pons is a relay station between the cerebrum and cerebellum. And the medulla is the site of decussation for most neurons. They are a part of the hind brain.

Question 29

What is the reticular formation?

Answer 29

A network of diffuse neurons involved in processes such as arousal/sleep, muscle tone, coordination of breathing and blood pressure. It is responsible for basal functions

Question 30

What is the function of the cerebellum?

Answer 30

To coordinate movements.

Question 31

What structures make up the diencephalon? (x4) What are each of their functions?

Answer 31

The thalamus (relay and integration centre for sensory information), the hypothalamus (centre of homeostasis), the pineal gland (secretes melatonin and controls circadian rhythms) and the pituitary gland (secretes hormones under the control of the hypothalamus).

Question 32

Why is the cerebrum folded?

Answer 32

it is to increase surface area and the amount of surface area os somehow related to intelligence

Question 33

What is a sulcus vs a gyrus?

Answer 33

A sulcus os the grove between two ridges. A gyros is the top of the hill

Question 34

What are the three regions of white matter within the cerebrum?

Answer 34

The basal “ganglia”, the limbic system, and the cereal cortex

Question 35

What type of functional area takes up the most space in the brain?

Answer 35

Association areas

Question 36

Where is the primary motor cortex? What is the other name for this centre? The cell bodies of what type of neurons originate here?

Answer 36

On the ridge just ANTERIOR to the central gyrus. A.k.a the precentral gyrus. The cell bodies of upper or first order motor neurons

Question 37

Where is the primary somatosensory cortex? What is the other name for this centre? Where does information for this cortex come from?

Answer 37

On the ride just POSTERIOR to the central gyrus. A.k.a. the post-central gyrus. The terminals of the sensory pathways from the skin, musculoskeletal system and viscera

Question 38

Where are the gustatory and olfactory cortices?

Answer 38

They are deep to the primary motor and somatosensory cortices.