Cell Types, Injury & Repair, Damage & Death Flashcards
What is the nervous system?
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).
The nervous system can be separated into the ____________________ & _____________________
- Central Nervous System (CNS)
- Peripheral Nervous System (PNS)
What does the Central Nervous System (CNS) consist of?
The brain & spinal cord.
What are the primary functions of the CNS?
It receives, interprets, & responds to body tissues.
What role does the hypothalamus play in the CNS?
It regulates the autonomic nervous system and basic physiological functions such as growth, respiration, sleep, digestion, excretion, & homeostasis.
How does the CNS contribute to personality?
Through learning, cognition, & memory, which form individual differences in characteristic patterns of thinking, feeling, & behaving.
What does the Peripheral Nervous System (PNS) consist of?
The nervous system outside the brain & spinal cord, including cranial nerves, spinal nerves, their roots & branches, peripheral nerves, & neuromuscular junctions.
What is the boundary between the Central Nervous System (CNS) & the Peripheral Nervous System (PNS)?
The intervertebral foramen.
What are cranial nerves?
Nerves that emerge directly from the brain, part of the PNS.
What are spinal nerves?
Nerves that emerge from the spinal cord, part of the PNS.
What are the two main categories of cells in the Central Nervous System (CNS)?
Neurons & Neuroglia.
What is the basic working unit of the brain called?
A neuron.
What are the main components of a neuron?
Cell body (soma), axon, & dendrites.
What is the function of dendrites?
They receive messages from other neurons.
How do neurons send signals?
Using action potentials, which are shifts in the neuron’s electric potential due to the flow of charged particles.
What are the types of neurons based on their structure?
Unipolar, bipolar, pseudounipolar, & multipolar.
What characterizes unipolar neurons?
They have only one process & are mostly found in invertebrates.
Where are bipolar neurons commonly found?
In sensory organs such as the retina, olfactory epithelium, & auditory system.
What is unique about pseudounipolar cells?
They have two processes that fuse during development into one short axon, allowing rapid signal transmission.
What are multipolar neurons characterized by?
Many dendrites originating from different regions of the cell body; they are the most common type in the CNS.
What are neuroglia?
A diverse class of cells that provide support, maintain homeostasis, and perform immune surveillance in the nervous system.
What is the function of the myelin sheath?
It insulates axons & speeds up electrical conduction.
What types of neuroglia are found in the Peripheral Nervous System (PNS)?
Schwann cells & satellite cells.
What do astrocytes do in the Central Nervous System (CNS)?
They maintain the blood-brain barrier, recycle ions & neurotransmitters, & provide structural support.
What is gliosis?
A response to CNS damage where astrocytes cluster to create a soft scar, limiting edema & preventing neuronal regeneration.
Why are CNS neurons considered permanent cells?
They do not normally regenerate and are replaced by fibrous scar tissue when destroyed.
What is neuroplasticity?
The ability of the brain to form and reorganize synaptic connections in response to learning, experience, or injury.
What is axonotmesis?
A type of nerve injury where the axon is damaged but the endoneurium & surrounding myelin sheath remain largely intact, allowing potential regrowth.
What is neurotmesis?
A severe type of nerve injury where the endoneurium is disrupted, making axonal regeneration unlikely.
What can cause cell damage or death in the CNS?
Hypoxia, trauma, autoimmune conditions, vascular lesions, infections, and exposure to toxins.
Why are CNS cells highly sensitive to oxygen levels?
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.
How quickly can permanent damage occur in CNS cells with oxygen loss?
Permanent damage usually begins within 4-10 minutes of oxygen deprivation.
What are some common causes of cell death in the CNS?
Decreased oxygen supply, genetic defects, trauma, compression, autoimmune conditions, vascular lesions, infections, & exposure to toxins.
What are potential causes of CNS damage in utero?
Genetic or congenital defects, maternal illness (especially viral), drug/alcohol exposure, intrauterine infections, & thyroid dysfunctions.
What birth-related issues can lead to CNS damage?
Birth canal hypoxia & direct trauma from forceps use.
How can fractures or dislocations affect the CNS?
Fractures of the skull or vertebrae can cause pressure or injury to CNS structures.
What role does compression play in CNS damage?
Edema, hematomas, or tumors can compress CNS cells, adversely affecting their function.
What types of direct trauma can cause CNS injury?
Auto accidents, falls, sports injuries, & penetrating injuries (e.g., gunshot wounds).
What is a coup-contrecoup injury?
An injury occurring at the site of trauma (“coup”) and on the opposite side of the brain (“contrecoup”).
How do autoimmune conditions impact the CNS?
Conditions like multiple sclerosis can attack oligodendrocytes, while diabetes & lupus can cause various CNS dysfunctions.
What are vascular lesions, & how do they affect the CNS?
Vascular lesions, such as strokes (occlusive or hemorrhagic), can create hypoxic conditions that damage CNS cells.
What types of infections can occur in the CNS?
Viral, bacterial, & fungal infections; commonly named by location (e.g., encephalitis, meningitis).
What are some common bacterial & viral infections in the CNS?
Pyogenic bacteria, lymphocytic viruses, & granulomatous fungi or yeast.
What role do poisons and toxins play in CNS cell damage?
They impair the cell’s ability to uptake or use oxygen by damaging or blocking receptor sites on cell membranes.
What are some examples of toxins that can damage CNS cells?
Drugs (prescription and recreational), chemicals, alcohol, heavy metals (e.g., mercury, lead), and carbon monoxide.
