The Nervous System

Flashcards covering the nervous system for exam review.

What is the nervous system?

A complex network of specialized cells that coordinates and regulates bodily functions, enabling communication between different parts of the body.

What are the three main functions of the nervous system?

Sensory input, integration, and motor output.

What is the direction of the electrical impulses in relation to the cell body for dendrites?

Towards the cell body.

What is the function of the myelin sheath?

Insulates the axon and increases the speed of electrical signals.

What is the function of the Nodes of Ranvier?

To allow fast signal conduction through saltatory conduction.

What is the synapse?

The junction between two neurons or a neuron and another cell where neurotransmitters are released.

What are astrocytes?

Star-shaped cells that maintain the blood-brain barrier, provide nutrients to nervous tissue, and repair the brain and spinal cord following traumatic injuries.

What cells produces the myelin sheath that insulates axons in the CNS, facilitating rapid signal transmission?

Oligodendrocytes.

What cells act as the primary immune defense in the CNS, scavenging pathogens and dead cells?

Microglial cells.

What cells line the ventricles of the brain and the central canal of the spinal cord and are involved in the production and circulation of cerebrospinal fluid?

Ependymal cells.

What cells produces the myelin sheath around axons in the PNS?

Schwann cells.

What cells surrounds neuron cell bodies within ganglia, providing structural support and regulating the exchange of materials between neuronal cell bodies and interstitial fluid.

Satellite cells.

What are the types of structural classification for neurons?

Unipolar, bipolar, multipolar, pseudounipolar, and anaxonic.

What is the primary role of interneurons?

Act as intermediaries between sensory and motor neurons, processing information within the central nervous system.

What neurotransmitter is released by cholinergic neurons?

Acetylcholine.

What neurotransmitter is released by adrenergic neurons?

Norepinephrine (noradrenaline).

What neurotransmitter is released by GABAergic neurons?

Gamma-aminobutyric acid (GABA).

What neurotransmitter is released by glutamatergic neurons?

Glutamate.

What neurotransmitter is released by dopaminergic neurons?

Dopamine.

What neurotransmitter is released by serotonergic neurons?

Serotonin.

What is the name of elevated ridges of tissue in the brain?

Gyri.

What is the definition of sulci?

Shallow grooves.

Which part of the brain is responsible for body movement, personality, problem-solving, planning, concentration, emotional reactions, sense of smell, the meaning of words, and general speech?

Frontal lobe.

Which part of the brain controls your sense of touch and pressure, sense of taste, and bodily awareness?

Parietal lobe.

Which part of the brain governs your sense of hearing, ability to recognize others, emotions, and long-term memory?

Temporal lobe.

Which part of the brain controls the important sense of sight?

Occipital lobe.

What are the three major structures of the diencephalon?

Thalamus, hypothalamus, and epithalamus.

What are the structures of the brain stem?

The midbrain, pons, and medulla oblongata.

What part of the brain contains more neurons than the cerebral cortex does?

Cerebellum.

What are the three parts of the Purkinje cells control?

Balance, gross motor coordination, and fine motor coordination.

The adult spinal cord terminates at L1 and L2; nerves from the end of the spinal cord form the _.

Cauda equina

What are the three connective tissue membranes that lie just external to the CNS?

Dura, arachnoid, and pia mater.

What is the function of the cerebrospinal fluid?

Forms a liquid cushion that gives buoyancy to CNS structures, reduces brain weight by 97%, protects the brain and spinal cord from blows and other trauma.

What are the types of sensory receptors?

Exteroceptors, interoceptors, and proprioceptors.

Where are Pacinian (Lamellar) Corpuscles found?

Deep dermis and subcutaneous tissue.

What do baroreceptors detect?

Changes in blood pressure.

What do the muscle spindles detect?

Changes in muscle length and stretch.

What is the function of the first-order neurons?

Sensory neurons that directly transmit signals from sensory receptors to the spinal cord or brainstem.

What is the function of the second-order neurons?

Located in the spinal cord or brainstem, these neurons relay information to the thalamus.

What is the function of the third-order neurons?

These neurons transmit signals from the thalamus to the appropriate sensory cortex in the brain for processing.

What is a nerve?

A bundle of axons (nerve fibers) that transmits electrical signals between the brain, spinal cord, and the rest of the body.

What tissue surrounds and insulates each individual axon within a nerve?

Endoneurium.

What tissue groups multiple axons into bundles called fascicles?

Perineurium.

What is the tough outer fibrous sheath that encloses the entire nerve?

Epineurium.

What are mixed nerves contain?

Both sensory and motor axons.

What is the regeneration potential for CNS?

Axons rarely regenerate due to inhibitory factors such as the presence of myelin-associated inhibitors and a lack of supportive cells.

How do Schwann cells help in PNS regeneration?

They create a tube that guides the regrowing axon to its target, ensuring proper reconnection, release growth factors that promote axon regrowth and support neuronal survival, and clear debris from the injury site, which is essential for the repair process.

What is the rate of axon regrowth under optimal conditions?

Approximately 1.5 mm per day.

List the cranial nerves

Olfactory, Optic, Oculomotor, Trochlear, Trigeminal, Abducens, Facial, Vestibulocochlear, Glossopharyngeal, Vagus, Accessory, Hypoglossal.

What is the function of the vagus nerve?

Controls autonomic functions in the thorax and abdomen, including heart rate, digestion, and respiratory rate.

What are the types of spinal nerves?

Cervical, thoracic, lumbar, sacral, coccygeal.

What is the function of the Cervical plexus?

Innervates the neck, ear, back of the head, and diaphragm (via the phrenic nerve).

What is the function of the Brachial plexus?

Controls shoulder, arm, forearm, and hand muscles.

What is the function of the Lumbar plexus?

Innervates the quadriceps muscle (responsible for knee extension) and provides sensation to the anterior thigh and part of the medial leg.

What is the function of the Sacral plexus?

Innervates the buttocks, lower limb, and pelvis.

What is the key role of somatic nervous system?

Responsible for the voluntary movements, wherein it transmits action potentials to the CNS towards the skeletal muscles.

What is the key role of the autonomic nervous system?

Involuntary movements.

What processes begins in the spinal cord, where the preganglionic neuron originates?

Mechanism of the autonomic nervous system.

What is the primary neurotransmitter of the sympathetic nervous system?

Norepinephrine.

What happens to the pupils under sympathetic nervous system?

Pupils dilating.

What happens to heart rate under sympathetic nervous system?

Heart rate increases.

What neurotransmitter promotes relaxation and conserves energy?

Acetylcholine.

What happens to the pupils under parasympathetic nervous system?

Pupil constricts.

What happens to the heart rate under parasympathetic nervous system?

Heart rate slows down.

What is another term for learned reflex

Acquired reflex

What processes of action potential is the neuron at rest, with a higher concentration of Na⁺ (sodium) ions outside and K⁺ (potassium) ions inside the cell?

Resting potential.

What processes of action potential is that a stimulus causes the membrane potential to become less negative?

Depolarization.

What processes of action potential that the membrane potential decreases, returning toward the resting potential?

Repolarization.

What is Threshold potential?

The minimum membrane potential that must be reached to trigger an action potential (typically around -55 mV).

No new action potential can be initiated, regardless of stimulus strength. What period is this?

Absolute Refractory Period.

A stronger-than-normal stimulus can initiate a new action potential. What period is this?

Relative Refractory Period.

What happens in Saltatory conduction?

In myelinated fibers, action potentials jump from one Node of Ranvier to the next, increasing the speed of conduction.

What is a synapse?

A specialized junction where one neuron communicates with another neuron—or with a muscle or gland cell.

Electrical synapses are formed by _.

Gap junctions.

Chemical synapses is when an action potential arrives at the presynaptic terminal, it triggers the opening of _.

Voltage-gated calcium channels.

What is primarily role of Acetylcholine?

Pivotal in both the peripheral and central nervous systems. In the periphery, it is the primary neurotransmitter at the neuromuscular junction where it triggers muscle contraction. In the brain, it plays key roles in attention, learning, and memory.

What are the five basic tastes?

Sour, salty, bitter, sweet, and umami (savory).

What is the start of the auditory sensation?

The journey starts with the cochlear ganglion, where glutamate signals from hair cells carry high-fidelity frequency and timing information to the cochlear nucleus, where two parallel processing streams (ventral and dorsal) begin specialized encoding.