Lecture 1 - Intro to HNN Block

Question 1

What are the two types of cell that make up the nervous system?

Answer 1

Neurons and Glial Cells

Question 2

What are the main parts of the neuron?

Answer 2

Cell body, axons and dendrites.

Question 3

What surrounds the nucleus of a neuron?

Answer 3

Extensive rough ER, Golgi apparatus, and mitochondria

Question 4

What organises the neuronal cytoplasm into different areas?

Answer 4

Neurofilaments (intermediate filaments) and microtubules

Question 5

What is the function of dendrites?

Answer 5

They receive information from other neurons or from sensory receptors and transmit the information towards the neuron cell body.

Question 6

What is the axon hillock?

Answer 6

Where the axon leaves the neuron cell body.

Question 7

How can neurons by classified?

Answer 7

According to their function or their structure.

Question 8

Describe multipolar neurons

Answer 8

They have many dendrites and a single axon. Most neurons in the CNS and nearly all motor neurons are multipolar.

Question 9

Describe Bipolar neurons

Answer 9

Bipolar neurons have two processes: one dendrite and one axon. Bipolar neurons are located in some sensory organs, such as in the retina of the eye and in the nasal cavity.

Question 10

Describe pseudo unipolar neurons.

Answer 10

Pseudo-unipolar neurons have a single process extending from the cell body. This process divides into two processes a short distance from the cell body. One process extends to the periphery, and the other extends to the CNS. The two extensions function as a single axon with small dendrite-like sensory receptor at the periphery.

Question 11

What are Glial cells?

Answer 11

Glial cells are the primarily supportive cells of the CNS and PNS, meaning these cells do not conduct action potentials. Neuroglia are much more numerous than neurons. Most neuroglia retain the ability to divide, whereas neurons do not..

Question 12

Name the 6 different types of Glial cell.

Answer 12

• Astrocytes
• Ependymal Cells
• Oligodendrocytes
• Schwann Cells
• Satellite Cells
• Microglia

Question 13

Describe the function of Astrocytes.

Answer 13

Astrocytes serve as the major supporting cells in the CNS. In this role, astrocytes can stimulate or inhibit the signalling activity of nearby neurons. In addition, astrocytes participate with the blood vessel endothelium to form a permeability barrier, the blood brain barrier, between the blood and the CNS. Astrocytes help limit damage to neural tissue; however, the repair process can form a scar that blocks the regeneration of damaged axons.

Question 14

Describe the function of Ependymal cells

Answer 14

Ependymal cells line the fluid-filled cavities (ventricles and canals) within the CNS. Some produce cerebrospinal fluid, and others, with cilia on the surface, help move the CSF through the CNS.

Question 15

Describe the function of Microglia.

Answer 15

Microglia act as immune cells of the CNS. They help protect the brain by removing bacteria and debris.

Question 16

Describe the function of Oligodendrocytes.

Answer 16

Oligodendrocytes act in the CNS to provide an insulating material that surrounds axons.

Question 17

Describe the function of Schwann cells.

Answer 17

Schwann cells act in the PNS to provide an insulating material that surrounds axons.

Question 18

Describe the function of Satellite cells.

Answer 18

They are similar in function to astrocytes. They are small cells that surround neurons in sensory, sympathetic and parasympathetic ganglia, helping to regulate the external chemical environment. They are highly sensitive to injury and inflammation, and appear to contribute to pathological states, such as chronic pain.

Question 19

Describe the Myelin Sheath.

Answer 19

Myelin sheaths are specialised layers that wrap around the axons of some neurons. They are formed either by the cell processes of oligodendrocytes in the CNS or Schwann cells in the PNS. Axons with a myelin sheath are called myelinated axons.

Question 20

What is the function of Myelin.

Answer 20

It is an excellent insulator that prevents almost all ion movement across the cell membrane.

Question 21

What are the nodes of Ranvier?

Answer 21

Gaps in the myelin sheath. They occur about every millimetre between the oligodendrocyte segments or between individual Schwann cells.

Question 22

What occurs at the nodes of Ranvier?

Answer 22

Ion movement

Question 23

What does myelination do?

Answer 23

It increases the speed and efficiency of action potential generation along the axon.

Question 24

What does Grey Matter consist of?

Answer 24

Groups of neuron cell bodies and their dendrites, where there is very little myelin.

Question 25

What is grey matter on the surface of the brain in the CNS called?

Answer 25

The Cortex

Question 26

What are clusters of grey matter located deeper within the brain called?

Answer 26

Nuclei

Question 27

What is a cluster of neuron cell bodies called in the PNS

Answer 27

Ganglion

Question 28

What is white matter?

Answer 28

Bundles of parallel axons with their myelin sheaths, which are whitish in colour.

Question 29

What forms nerves?

Answer 29

Bundles of axons and associated connective tissue.

Question 30

What does the primary motor cortex correspond with?

Answer 30

The pre-central gyrus

Question 31

What is the pyramidal tract composed of?

Answer 31

The Corticospinal tract and the corticobulbar tract.

Question 32

What does the corticospinal tract supply?

Answer 32

The musculature of the body

Question 33

What does the corticobulbar tract supply?

Answer 33

The musculature of the head and neck

Question 34

From where does the pyramidal tract get its name?

Answer 34

The medullary pyramids of the medulla oblongata.

Question 35

Where does the pyramidal tract originate?

Answer 35

The cerebral cortex

Question 36

What are the main language areas of the brain?

Answer 36

Broca's Area - motor aspect of speech | Wernicke's Area -understanding of speech

Question 37

What are people commonly left dominant for?

Answer 37

Speech

Question 38

What is the blood supply for the area of the brain supplying the leg?

Answer 38

Anterior Cerebral Artery

Question 39

What is the blood supply for the area of the brain supplying the right side of the body (apart from the leg)?

Answer 39

The left middle cerebral artery.

Question 40

What causes MS?

Answer 40

Discrete lesions affecting myelin that surrounds many CNS axons and can be seen as plaques in white matter of brain and spinal cord.

Question 41

What are some of the symptoms of MS?

Answer 41

- Partial loss of vision - Double vision (altered eye movements) - Sensory changes (e.g. numbness) - Motor Symptoms (e.g. weakness ataxia)

Question 42

Describe spinal nerves

Answer 42

Spinal nerves are nerve fibres that are travelling to/from the limbs from the spinal cord.

Question 43

When do spinal nerves become peripheral nerves?

Answer 43

One they have passed through plexuses (such as brachial and lumbosacral plexuses).

Question 44

What is a dermatome?

Answer 44

A region of skin supplied by a single spinal nerve .

Question 45

What is paraesthesia?

Answer 45

A tingling sensation.

Question 46

What is affected first in sensory loss?

Answer 46

The longest fibres (stocking and glove distribution). This can occur in conditions such as vitamin B12 deficiency. Long fibres are more metabolically at risk than others

Question 47

What are the three main anatomically divisions of the ANS?

Answer 47

- Sympathetic - Parasympathetic - Enteric

Question 48

What is the enteric nervous system composed of?

Answer 48

The intrinsic nerve plexuses of the G.I tract. It has sufficient integrative capabilities to allow it to function independently of the CNS.

Question 49

Is the ANS mainly voluntary or involuntary?

Answer 49

Involuntary

Question 50

What processes does the ANS regulate?

Answer 50

- Contraction and relaxation of vascular and visceral smooth muscle - All exocrine and certain endocrine secretions - The heartbeat - Energy Metabolism, particularly in the liver and skeletal muscle.

Question 51

Describe the autonomic efferent pathway.

Answer 51

The autonomic efferent pathway consists of 2 neurons arranged in series.

Question 52

Describe the somatic motor system

Answer 52

The somatic motor system consists of a single motor neuron connecting the CNS to skeletal muscle fibres.

Question 53

Where are discrete parasympathetic ganglia found? Give an example of one.

Answer 53

The Head and Neck - the ciliary ganglion.

Question 54

Where are the cell bodies of sympathetic pre-ganglionic neurons located?

Answer 54

In the lateral horn of the grey matter of the thoracic and lumbar segments of the spinal cord.

Question 55

Where do sympathetic pre-ganglionic fibres synapse?

Answer 55

In the paravertebral chains of sympathetic ganglia, lying on either side of the spinal cord

Question 56

What is the exception to the two neuron arrangement in the ANS?

Answer 56

The innervation of the adrenal medulla. The catecholamine-secreting cells of the adrenal medulla are, in effect, modified post-ganglionic sympathetic neurons, and the nerves supplying the gland are equivalent to pre-ganglionic fibres.

Question 57

What are the parasympathetic cranial nerves? What do they supply?

Answer 57

- Oculomotor Nerve (eye) - Facial Nerve and Glossopharyngeal Nerve (Salivary Glands and Nasopharynx) - Vagus Nerve (thoracic and abdominal viscera)

Question 58

What do the nervi erigentes do?

Answer 58

They are the nerves that are stimulated to evoke a genital erection.