2nd exam

What are the functions of the nervous system?

Integrating, processing, coordinating sensory data and motor commands; Intelligence, memory, learning and emotion

What is the Central Nervous System (CNS)?

Made up of the brain and the spinal cord

What is the Peripheral Nervous System (PNS)?

Provides sensory information to the CNS and carries motor commands from the CNS to peripheral tissues and systems

What are the subdivisions of the Peripheral Nervous System (PNS)?

Afferent nervous system and Efferent nervous system

What is the Afferent nervous system responsible for?

Bringing sensory information to the CNS

What is the Efferent nervous system responsible for?

Carrying motor commands to muscles or glands

What are the subdivisions of the Efferent nervous system?

Somatic nervous system and Autonomic nervous system

What does the Somatic nervous system control?

Skeletal muscle contractions (voluntary)

What does the Autonomic nervous system regulate?

Smooth muscle, cardiac muscle, and glandular activity (involuntary)

What are the two divisions of the Autonomic nervous system?

Parasympathetic (relaxing) and Sympathetic (stimulating)

What are Neuroglia or glial cells?

Cells that support, nourish, and protect the neurons in the CNS and PNS

What is the function of Astrocytes?

Shield neurons from direct contact with other neurons; Maintain blood-brain barrier; Create a framework for CNS; Performs limited repairs of damaged neural tissue; Guides embryonic neural development; Controls the interstitial environment

What is the function of Oligodendrocytes?

Wrap around axons of CNS neurons for myelination

What is the function of Microglia?

Engulf cellular debris, waste products, and pathogens like macrophages

What are Gliomas?

Tumors derived from glial cells; typically highly malignant and fast-growing

What are the types of glial cells in the CNS?

Astrocytes, Oligodendrocytes, Microglia, Ependymal cells

What is the function of Ependymal cells?

Line the ventricles of the brain and the central canal of the spinal cord; assist in the production and circulation of cerebrospinal fluid

What is the function of Schwann cells?

Wrap around axons of PNS neurons for myelination

What is the function of Satellite cells?

Surround and support cell bodies of neurons in the PNS

What are ependymal cells?

Cells that line the ventricles of the brain and central canal of the spinal cord.

What is the function of ependymal cells?

To create passages filled with cerebrospinal fluid (CSF).

What are Schwann cells?

Cells found in the peripheral nervous system (PNS) that myelinate axons from PNS neurons and direct regeneration of damaged axons.

What are satellite cells?

Cells that regulate the exchange of nutrients and waste products and surround neuron cell bodies in ganglia.

What are ganglia?

Groupings of PNS neuron cell bodies.

What is the function of neurons?

To be responsible for all nervous system activity.

What is an action potential?

A sudden change in electrochemical force that propagates on the membrane surface of a neuron.

What is the cell body or soma?

The part of the neuron that contains a large, round nucleus and is responsible for the synthesis of cell proteins.

What is the cytoplasm (perikaryon)?

The part of the neuron's cell body that contains neurofilaments, neurotubules, and neurofibrils, giving the cell body shape and support.

What are Nissl bodies?

Large clusters of rough endoplasmic reticulum and free ribosomes found in the cell body that stain darkly and are responsible for protein synthesis.

What are dendrites?

Slender processes that receive or initiate impulses and are short and highly branched, acting like an antenna for the neuron.

What is an axon?

A single, long cytoplasmic process of a neuron that propagates electrical impulses (action potentials) to another neuron, a gland, or a muscle cell.

What is the axon hillock?

The thickened region at the base of the axon where action potentials are initiated.

What is the initial segment?

The base of the axon where it attaches to the cell body.

What is axoplasm?

The cytoplasm of the axon.

What is axolemma?

The membrane surrounding the axon.

What are axon collaterals?

Branches of the axon that are usually at right angles to the main axon and allow one neuron to pass the signal to multiple effectors.

What are telodendria?

Fine branches at the end of the axon or axon collaterals.

What is a synaptic terminal?

Ends of the axon telodendria.

What is a myelin sheath?

Multilayered lipid and protein covering that surrounds axons.

What produces the myelin sheath?

Neuroglia (Schwann cells and oligodendrocytes).

What is the function of the myelin sheath?

Acts as an electrical insulator and increases the speed of nerve impulses.

How are axons wrapped by Schwann cells in the PNS?

Schwann cells wrap around the axon up to 100 times, forming a jellyroll structure.

What is the outermost layer of the Schwann cell called?

Neurilemma.

What are Nodes of Ranvier?

Gaps in the myelin sheath.

How are axons myelinated in the CNS?

Oligodendrocytes form ~15 layers of myelin.

What is the difference between myelinated and unmyelinated axons?

Myelinated axons form white matter, while unmyelinated axons form gray matter.

What are the types of structural classification of neurons?

Bipolar, unipolar, and multipolar neurons.

Describe bipolar neurons.

They have one dendrite and one axon, with the cell body in the middle. Found in special sense organs.

Describe unipolar neurons.

They have a continuous dendritic process and axon, with the cell body off to the side. Found in long sensory pathways.

Describe multipolar neurons.

They have multiple dendrites and one axon. Most common type of neuron.

What is the functional classification of neurons?

Sensory (afferent), motor (efferent), and interneurons (association neurons).

What do sensory neurons do?

Transmit nerve impulses from receptors to the CNS.

What are the two types of sensory neurons?

Somatic sensory neurons (external environment) and visceral sensory neurons (internal environment).

What do motor neurons do?

Transmit nerve impulses from the CNS to effectors.

What are the two types of motor neurons?

Somatic motor neurons (skeletal muscles) and visceral motor neurons (smooth muscle, cardiac muscle, glands, and adipose tissue).

What do interneurons do?

Distribute sensory information and coordinate motor responses.

What is the process of damage and repair in mammalian neurons?

Limited regeneration in PNS, little to no repair in CNS

How can dendrites and myelinated axons be repaired in the PNS?

If cell body is intact and Schwann cells are active

What happens to Nissel bodies during damage and repair?

They break up into small masses (chromatolysis)

What is Wallerian degeneration?

Breakdown of myelin sheath and debris pickup by macrophages

What remains after Wallerian degeneration in the PNS?

Neurolemma and Schwann cells

What do Schwann cells do after injury in the PNS?

Multiply and grow towards each other to form a regeneration tube

What can prevent repair in the PNS?

Filling of the gap with collagen fibers or if the gap is too large

Is repair possible in the CNS?

Little to no repair even if the cell body is intact

What do oligodendrocytes do in the CNS?

They do not form a neurolemma and inhibit regeneration

What do astrocytes do after injury in the CNS?

Proliferate quickly and form scar tissue that acts as a physical barrier to regeneration

What is the transmembrane potential?

The potential difference across a cell membrane.

What is the unit of measurement for transmembrane potential?

Volt (V).

What is the resting membrane potential (RMP) of a cell?

-70 mV.

What ions are present inside the cell?

K+ ions and negatively charged proteins.

What ions are present outside the cell?

Na+ and Cl- ions.

What is the purpose of a cell membrane?

To prevent free movement of ions.

What are passive forces in the cell membrane?

Chemical gradients, electrical gradients, and electrochemical gradients.

What is a chemical gradient?

Movement of ions from an area of high concentration to low concentration.

Give an example of a chemical gradient.

K+ leaking out of the cell from high concentration (inside) to low concentration (outside).

What is an electrical gradient?

Movement of ions toward the opposite charge.

Give an example of an electrical gradient.

Na+ being attracted to the negative charge inside the cell.

What is an electrochemical gradient?

The sum of the chemical and electrical forces acting on an ion across the cell membrane.

What is the purpose of active forces in the cell membrane?

To actively transport ions across the membrane.

What is the difference between passive and active forces?

Passive forces rely on concentration and charge gradients, while active forces require energy.

What is the role of passive forces in maintaining the resting membrane potential?

Passive forces help establish and maintain the transmembrane potential.

What is the role of active forces in maintaining the resting membrane potential?

Active forces help regulate and adjust the transmembrane potential.

How do passive forces contribute to the resting membrane potential?

Chemical and electrical gradients contribute to the charge difference across the membrane.

How do active forces contribute to the resting membrane potential?

Active transport mechanisms actively pump ions across the membrane to maintain the charge difference.

What is the overall effect of passive and active forces on the resting membrane potential?

Passive forces establish the initial potential, while active forces fine-tune and maintain the potential.

What is the significance of the resting membrane potential?

It is essential for various cellular processes, including nerve impulse transmission and muscle contraction.

What is the function of the sodium-potassium ATPase pump?

To maintain RMP and return cells to RMP after a change in membrane potential

How many Na+ molecules does the Na+/K+ pump remove for every 2 K+ molecules it brings into the cell?

3

How many ATP molecules are required for each movement of the Na+/K+ pump?

1

What is the role of the Na+/K+ pump in maintaining the resting membrane potential (RMP)?

It helps maintain the -70mV RMP across the membrane

What percentage of the nervous system's ATP is used by the Na+/K+ pump?

70%

Why does nervous tissue require high levels of oxygen and glucose?

Because the Na+/K+ pump uses a significant amount of ATP

What can happen if there is deprivation of oxygen or glucose in nervous tissue?

Damage can occur quickly

What are passive channels or leak channels?

Channels that are always open and allow ions to move in or out of the cell freely based on concentration gradient

What are chemically regulated channels?

Channels that open or close when they bind specific chemicals (ligands)

Where are chemically regulated channels found?

On dendrites and neuron cell bodies

What are voltage regulated channels?

Channels that open or close in response to changes in transmembrane potential

Where are voltage regulated channels found?

On axons and other excitable membranes

What are mechanically regulated channels?

Channels that open or close in response to physical distortion of a membrane

What are the sensory receptors for touch, pressure, and vibration?

Mechanically regulated channels