Cell Types, Injury & Repair, Damage & Death

Question 1

What is the nervous system?

Answer 1

Body’s command centre. Originating from brain, controls movement thoughts & automatic responses to outside world. Also controls other
body systems & processes, ie. digestion, breathing & sexual development (puberty).

Question 2

The nervous system can be separated into the ____________________ & _____________________

Answer 2

• Central Nervous System (CNS)
• Peripheral Nervous System (PNS)

Question 3

What does the Central Nervous System (CNS) consist of?

Answer 3

The brain & spinal cord.

Question 4

What are the primary functions of the CNS?

Answer 4

It receives, interprets, & responds to body tissues.

Question 5

What role does the hypothalamus play in the CNS?

Answer 5

It regulates the autonomic nervous system and basic physiological functions such as growth, respiration, sleep, digestion, excretion, & homeostasis.

Question 6

How does the CNS contribute to personality?

Answer 6

Through learning, cognition, & memory, which form individual differences in characteristic patterns of thinking, feeling, & behaving.

Question 7

What does the Peripheral Nervous System (PNS) consist of?

Answer 7

The nervous system outside the brain & spinal cord, including cranial nerves, spinal nerves, their roots & branches, peripheral nerves, & neuromuscular junctions.

Question 8

What is the boundary between the Central Nervous System (CNS) & the Peripheral Nervous System (PNS)?

Answer 8

The intervertebral foramen.

Question 9

What are cranial nerves?

Answer 9

Nerves that emerge directly from the brain, part of the PNS.

Question 10

What are spinal nerves?

Answer 10

Nerves that emerge from the spinal cord, part of the PNS.

Question 11

What are the two main categories of cells in the Central Nervous System (CNS)?

Answer 11

Neurons & Neuroglia.

Question 12

What is the basic working unit of the brain called?

Answer 12

A neuron.

Question 13

What are the main components of a neuron?

Answer 13

Cell body (soma), axon, & dendrites.

Question 14

What is the function of dendrites?

Answer 14

They receive messages from other neurons.

Question 15

How do neurons send signals?

Answer 15

Using action potentials, which are shifts in the neuron’s electric potential due to the flow of charged particles.

Question 16

What are the types of neurons based on their structure?

Answer 16

Unipolar, bipolar, pseudounipolar, & multipolar.

Question 17

What characterizes unipolar neurons?

Answer 17

They have only one process & are mostly found in invertebrates.

Question 18

Where are bipolar neurons commonly found?

Answer 18

In sensory organs such as the retina, olfactory epithelium, & auditory system.

Question 19

What is unique about pseudounipolar cells?

Answer 19

They have two processes that fuse during development into one short axon, allowing rapid signal transmission.

Question 20

What are multipolar neurons characterized by?

Answer 20

Many dendrites originating from different regions of the cell body; they are the most common type in the CNS.

Question 21

What are neuroglia?

Answer 21

A diverse class of cells that provide support, maintain homeostasis, and perform immune surveillance in the nervous system.

Question 22

What is the function of the myelin sheath?

Answer 22

It insulates axons & speeds up electrical conduction.

Question 23

What types of neuroglia are found in the Peripheral Nervous System (PNS)?

Answer 23

Schwann cells & satellite cells.

Question 24

What do astrocytes do in the Central Nervous System (CNS)?

Answer 24

They maintain the blood-brain barrier, recycle ions & neurotransmitters, & provide structural support.

Question 25

What is gliosis?

Answer 25

A response to CNS damage where astrocytes cluster to create a soft scar, limiting edema & preventing neuronal regeneration.

Question 26

Why are CNS neurons considered permanent cells?

Answer 26

They do not normally regenerate and are replaced by fibrous scar tissue when destroyed.

Question 27

What is neuroplasticity?

Answer 27

The ability of the brain to form and reorganize synaptic connections in response to learning, experience, or injury.

Question 28

What is axonotmesis?

Answer 28

A type of nerve injury where the axon is damaged but the endoneurium & surrounding myelin sheath remain largely intact, allowing potential regrowth.

Question 29

What is neurotmesis?

Answer 29

A severe type of nerve injury where the endoneurium is disrupted, making axonal regeneration unlikely.

Question 30

What can cause cell damage or death in the CNS?

Answer 30

Hypoxia, trauma, autoimmune conditions, vascular lesions, infections, and exposure to toxins.

Question 31

Why are CNS cells highly sensitive to oxygen levels?

Answer 31

They are metabolically active, using 20-30% of available oxygen/glucose at any time, making them sensitive to hypoxia (reduction of oxygen) and variations in blood sugar.

Question 32

How quickly can permanent damage occur in CNS cells with oxygen loss?

Answer 32

Permanent damage usually begins within 4-10 minutes of oxygen deprivation.

Question 33

What are some common causes of cell death in the CNS?

Answer 33

Decreased oxygen supply, genetic defects, trauma, compression, autoimmune conditions, vascular lesions, infections, & exposure to toxins.

Question 34

What are potential causes of CNS damage in utero?

Answer 34

Genetic or congenital defects, maternal illness (especially viral), drug/alcohol exposure, intrauterine infections, & thyroid dysfunctions.

Question 35

What birth-related issues can lead to CNS damage?

Answer 35

Birth canal hypoxia & direct trauma from forceps use.

Question 36

How can fractures or dislocations affect the CNS?

Answer 36

Fractures of the skull or vertebrae can cause pressure or injury to CNS structures.

Question 37

What role does compression play in CNS damage?

Answer 37

Edema, hematomas, or tumors can compress CNS cells, adversely affecting their function.

Question 38

What types of direct trauma can cause CNS injury?

Answer 38

Auto accidents, falls, sports injuries, & penetrating injuries (e.g., gunshot wounds).

Question 39

What is a coup-contrecoup injury?

Answer 39

An injury occurring at the site of trauma ("coup") and on the opposite side of the brain ("contrecoup").

Question 40

How do autoimmune conditions impact the CNS?

Answer 40

Conditions like multiple sclerosis can attack oligodendrocytes, while diabetes & lupus can cause various CNS dysfunctions.

Question 41

What are vascular lesions, & how do they affect the CNS?

Answer 41

Vascular lesions, such as strokes (occlusive or hemorrhagic), can create hypoxic conditions that damage CNS cells.

Question 42

What types of infections can occur in the CNS?

Answer 42

Viral, bacterial, & fungal infections; commonly named by location (e.g., encephalitis, meningitis).

Question 43

What are some common bacterial & viral infections in the CNS?

Answer 43

Pyogenic bacteria, lymphocytic viruses, & granulomatous fungi or yeast.

Question 44

What role do poisons and toxins play in CNS cell damage?

Answer 44

They impair the cell's ability to uptake or use oxygen by damaging or blocking receptor sites on cell membranes.

Question 45

What are some examples of toxins that can damage CNS cells?

Answer 45

Drugs (prescription and recreational), chemicals, alcohol, heavy metals (e.g., mercury, lead), and carbon monoxide.