Neuron Anatomy and Glial Cells

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Questions and Answers

What is the role of the precentral gyrus in the brain?

Regulating sensory perception

Facilitating memory and learning

Control of movement (correct)

Processing auditory information

Which lobe of the brain is primarily responsible for vision?

Occipital lobe (correct)

Parietal lobe

Temporal lobe

Frontal lobe

What distinguishes a fissure from a sulcus?

A fissure is a deep groove, while a sulcus is a shallow groove. (correct)

There is no distinction; they are the same structure.

Fissures separate the lobes, while sulci do not.

A fissure is a shallow groove, while a sulcus is deeper.

Which major sulcus divides the frontal and parietal lobes?

Central sulcus Signup and view all the answers

What function is primarily associated with the temporal lobe?

Speech comprehension Signup and view all the answers

What is the primary role of cerebrospinal fluid (CSF)?

It acts as a shock absorber. Signup and view all the answers

Which layer of the meninges is the innermost and tightly adheres to the brain?

Pia mater Signup and view all the answers

During which developmental stage does neuroplasticity play a crucial role in optimizing neural connections?

Adolescence Signup and view all the answers

What does 'experience-dependent neuroplasticity' primarily facilitate?

Change in neural structure based on experiences. Signup and view all the answers

What are the four CSF-filled spaces inside the brain known as?

Ventricles Signup and view all the answers

What structure is formed by the thickening of the ectoderm during brain development?

Neural Plate Signup and view all the answers

Which neuropore closes first during the formation of the neural tube?

Superior neuropore Signup and view all the answers

What is the primary function of the spinal cord?

Conduit for information flow to and from the brain Signup and view all the answers

Which part of the brain connects the spinal cord and cerebrum and regulates vital functions?

Brainstem Signup and view all the answers

The thalamus is involved in which of the following functions?

Processing emotional information Signup and view all the answers

What are the primary functions of the hypothalamus?

Homeostasis and regulation of visceral functions Signup and view all the answers

Which region of the brain is primarily responsible for motor learning and coordination?

Cerebellum Signup and view all the answers

Which of the following is NOT a component of the diencephalon?

Pons Signup and view all the answers

What anatomical change is typically observed in the brain during aging?

Decreased neurotransmitter activity Signup and view all the answers

Which factor is NOT mentioned as influencing changes in brain aging?

Dietary supplements Signup and view all the answers

What is the primary etiology of spina bifida?

Maternal nutritional deficiencies Signup and view all the answers

What symptom is commonly associated with hydrocephalus?

Enlarged head in infants Signup and view all the answers

What is the prognosis typically associated with meningitis caused by a viral infection?

Rarely life-threatening Signup and view all the answers

What is the primary function of dendrites in a neuron?

They receive and integrate information. Signup and view all the answers

Which type of glial cell is responsible for forming myelin in the central nervous system?

Oligodendrocytes Signup and view all the answers

What is the role of presynaptic terminals?

To release neurotransmitters into the synaptic cleft. Signup and view all the answers

What distinguishes gray matter from white matter in the nervous system?

Gray matter integrates information through cell bodies. Signup and view all the answers

Which function is associated with astrocytes in the central nervous system?

They regulate neuronal communication. Signup and view all the answers

What is the primary function of microglia in the central nervous system?

To act as the immune system of the CNS. Signup and view all the answers

What is a key characteristic of stem cells in the nervous system?

They have the ability to self-renew and differentiate. Signup and view all the answers

During which phase does the neural tube formation occur in embryonic development?

Day 15-28 Signup and view all the answers

Study Notes

Neuron Anatomy

Cell Body (Soma): The metabolic center of the neuron; receives and integrates information.
Axon Hillock: The area where the axon arises from the cell body.
Dendrites: Primary input site of the neuron; receive information and increase the neuron’s receptive surface.
Axon: The main output unit of the neuron; sends information to other neurons.
Presynaptic Terminal: Specialized areas at the distal axon; release neurotransmitters into the synaptic cleft.

Glial Cells

Provide structural support, electrical insulation, and act as scavengers.
Play a crucial role in nervous system development.

Microglia

Act as the immune system of the CNS.
Clean the neural environment.
Phagocytes that remove debris from dying cells.
Activated during NS development and following injury, infection, or disease.

Macroglia

Astrocytes (CNS)
- Clean the neural environment.
- Part of the blood-brain barrier.
- Connect neurons and blood capillaries, providing nutrition to neurons.
- Regulate neuronal communication.
Oligodendrocytes (CNS) & Schwann Cells (PNS)
- Form myelin to insulate axons.
  - CNS: Oligodendrocytes
  - PNS: Schwann Cells.

Stem Cells

Mature neurons cannot reproduce.
Stem cells: Undifferentiated cells that:
- Self-renew.
- Differentiate into most types of neurons and glial cells.
- Populate developing and degenerating regions of the CNS.

Gray Matter

Consists of cell bodies.
Integrates information.
CNS: Nuclei (cortex, horn).
PNS: Ganglia.

White Matter

Consists of axons and myelin.
Conveys information.
CNS: Tracts, fasciculus, column, peduncle, lemniscus, capsule.
PNS: Nerve.

Development of the Nervous System

Starts in-utero with the formation of the neural tube.
Two phases of the Embryonic Stage (Day 15- end of 8th week):
- Neural tube formation (Day 18-26).
- Brain formation (Begins Day 28).

Neural Tube Formation

After fertilization, cell multiplication forms an embryo (3 layers).
The neural plate forms from the thickening of a portion of the ectoderm (outer layer of embryo).
The edges of the neural plate fold to form the neural groove (Day 18).
The neural tube is formed when the edges of the groove touch (Day 21).

Closure of the Neural Tube

The superior neuropore closes first (by Day 27).
The inferior neuropore closes ~3 days later.
The tube differentiates into two concentric circles (by Day 26):
- Inner layer becomes gray matter of the spinal cord.
- Outer layer becomes white matter of the spinal cord.

Spinal Cord

Vertebral Column: 33 segments.
Spinal Cord: Travels through the vertebral column with 31 pairs of spinal nerves arising from each segment.
- Conus Medullaris: The tapering end of the spinal cord.
- Cauda Equina: The bundle of nerve roots at the end of the spinal cord.

Spinal Cord Function

Conduit for information flow to and from the brain.
Control of limb and trunk muscles.
- Cervical
- Thoracic
- Lumbar
- Sacral
Processing of information.

Development of the Brain

Brain formation begins when the superior neuropore closes (Day 28).

Brainstem

Connects the spinal cord and cerebrum.
Integrates information and regulates vital functions.
Medulla:
- Most caudal end.
- Life support centers.
Pons:
- Rostral to the medulla.
- Regulates respiration; bridge to the cerebellum.
Midbrain:
- Most rostral section of the brainstem.

Cerebellum

Located caudal to the cortex, posterior to the brainstem.
Purpose:
- Coordination of movement.
- Controls range and force of movement.
- Balance.
- Motor Learning/memory.

Diencephalon

Caudal to the cortex, superior to the brainstem.
Includes:*
- Thalamus
- Hypothalamus
- Epithalamus
- Subthalamus

Diencephalon: Thalamus

Relays almost all information to the cerebral cortex.
Integrates sensation.
Processes emotional information.
Involved in memory.
Regulates consciousness, arousal, and attention.

Diencephalon: Hypothalamus

Homeostasis.
Regulation of visceral and endocrine functions.
- Eating, reproduction, motivated behaviors.
- Regulation of circadian rhythm.
- Endocrine regulation of growth, metabolism, etc.

Sulci, Gyri, and Fissures

Cortex is not smooth, but has bumps and grooves.
Sulci, gyri, and fissures separate the cerebral cortex into lobes and hemispheres.
Gyrus: Bump/ridge.
Sulcus: Groove/valley.
Fissure: Deep groove.

Major Sulci/Fissures

Central Sulcus: Divides the frontal and parietal lobes.
Sylvian/Lateral Fissure: Divides the frontal and parietal lobes from the temporal lobe.
Medial Longitudinal Fissure: Divides the right and left hemispheres.

Major Gyri

Precentral Gyrus: Anterior to the central sulcus; the most posterior aspect of the frontal lobe.
Postcentral Gyrus: Posterior to the central sulcus; the most anterior aspect of the parietal lobe.

Telencephalon

The largest part of the brain.
Consists of the two cerebral hemispheres.

Telencephalon: Cerebral Hemispheres

The two cerebral hemispheres are connected.
Each hemisphere is divided into 4 lobes:
Frontal Lobe
Parietal Lobe
Temporal Lobe
Occipital Lobe

Frontal Lobe

Control of movement.
Personality.
Executive functions (planning, self-monitoring, judgment, etc.).
“M1”: Primary motor cortex (precentral gyrus).

Parietal Lobe

Sensory perception.
Body image/schema.
Spatial awareness.
“S1”: Primary somatosensory cortex (postcentral gyrus).

Temporal Lobe

Hearing.
Speech comprehension.
Memory.
Aspects of learning.

Occipital Lobe

Vision.

Telencephalon: Basal Ganglia

Nuclei located deep within the cerebral hemispheres.
Functions:
- Initiation and control of movement.
- Cognition and emotion.

Telencephalon: Limbic System

Nuclei located deep within the cerebral hemispheres.
Hippocampus
Amygdala
Functions:
- Memory, learning, emotion, motivation.

Supports of the Nervous System

Vascular System: Supports neurons and glial cells.
Cerebrospinal Fluid (CSF) System: Supports neurons and glial cells.
- CSF: Cerebrospinal fluid.
- Ventricles: 4 CSF-filled spaces inside the brain.
- Meninges: Connective tissue surrounding the brain and spinal cord; protective, also circulatory functions.

Ventricles & Cerebrospinal Fluid (CSF)

CSF flows through ventricles and around the spinal cord in a unidirectional manner.
Functions of CSF:
- Helps maintain homeostasis.
- Shock absorber.
- Fluid transport system.

Meninges

Three Layers:
- Dura Mater: Outer layer, tough; surrounds brain & spinal cord.
- Arachnoid Mater: Middle layer, delicate and loosely attached to the dura mater; subarachnoid space.
- Pia Mater: Innermost layer, very delicate; tightly adheres to brain & spinal cord.

Neuroplasticity

Neuroplasticity: The ability of neurons to change their function, chemical profile, and/or structure.
Involved in:
- Habituation
- Learning and memory (experience-dependent neuroplasticity).
- Recovery after injury.
- Maladaptation after injury.

Post-Natal Development

“Critical periods” of development are periods of time when the nervous system optimizes neural connections.
Experiences shape the brain (“use it or lose it”).

Post-Natal Development: Adolescent Years

The adolescent brain is not finished developing.
Growth spurts occur with proliferation and pruning, particularly in the prefrontal cortex.
What teens do matters!

Aging & the Brain

In typical aging:
- Anatomical Changes:
- Cortex thins.
- White matter decreases.
- Neurotransmitter/receptor changes.
- Functional Changes:
- Sensation, motor skills, speed, memory, and vision impacted.
Factors can slow or hasten these changes: Weight, exercise, rest, stress.

Important Terminology for Clinical Correlates

Etiology: Cause/origin of a disease or abnormal condition.
Pathology: What is actually happening in the body.
Prognosis: The prospect of recovery from disease.

Clinical Correlates: Anencephaly

Etiology: Chromosomal abnormalities, maternal nutritional deficiencies, maternal hyperthermia.
Pathology: Superior neuropore does not close; forebrain does not develop and skull/skin does not form over incomplete brain.
Prognosis: Most fetuses die before birth, almost none survive longer than a week following birth.

Clinical Correlates: Spina Bifida

Etiology: Maternal nutritional deficiencies.
Pathology: Inferior neuropore does not close; vertebrae do not close around the incomplete neural tube.
Symptoms: Vary based on location and severity of malformation (e.g., sensory & motor impairment of lower limbs, bowel/bladder difficulties, intellectual disability).
Prognosis: Impairment is usually stable.

Clinical Correlates: Hydrocephalus

Etiology: Congenital or acquired.
Pathology: Buildup of CSF in the ventricles causes enlargement of ventricles, compressing brain tissue.
Symptoms: Enlarged head (fetus/infant); impairments in balance, gait, bladder control, and executive functions (e.g., emotions, planning, memory, etc.).

Clinical Correlations: Meningitis

Etiology: Usually viral infection.
Pathology: Inflammation of the meninges.
Symptoms: Headache, fever, confusion, vomiting, neck stiffness.
Prognosis: Viral meningitis rarely life-threatening; bacterial meningitis is rare but potentially fatal.

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Description

Explore the structure and function of neurons and glial cells in the nervous system. This quiz covers components like the soma, axon, dendrites, and the various types of glial cells, including microglia and macroglia. Test your understanding of their roles in maintaining neural health and function.