Nervous System Overview

Nervous System

• Voluntary control of skeletal muscles is provided by the somatic nervous system.

Peripheral Nervous System

• The afferent division of the peripheral nervous system carries sensory information to the central nervous system.

Glial Cells

• Astrocytes, ependymal cells, and oligodendrocytes are all glial cells found in the central nervous system.
• Satellite cells are found in the peripheral nervous system.
• Ependymal cells line the ventricles and spinal canal, producing and distributing cerebrospinal fluid.

Neurotransmitters

• Neurotransmitters are released from a synapse with the aid of calcium ions.

Synapse

• The synapse is the site of intercellular communication between neurons.

Sensory Neurons

• Sensory neurons of the PNS are unipolar.

Neuron Resting Potential

• At rest, a typical neuron's ion exchange pump transports 3 sodium ions out and 2 potassium ions in for every cycle.

Depolarization

• Opening sodium channels in a neuron's membrane leads to depolarization.

Impulse Conduction Speed

• Impulse conduction speed is fastest in type A fibers.

Interneurons

• Interneurons coordinate information, connect different brain regions, and relay information.

Astrocytes Function

• Astrocytes control the interstitial environment, guide neuron development, maintain the blood-brain barrier, and participate in repairing damaged neural tissue.

Spinal Cord Enlargements

• Spinal cord enlargements are located in segments controlling limbs.

Spinal Cord Segments

• The spinal cord is divided into 31 segments, corresponding to the number of spinal nerve pairs.

Dorsal Root Ganglia

• Dorsal root ganglia contain cell bodies of sensory neurons.

Reflexes

• The crossed extensor reflex complements a withdrawal reflex by adapting the opposite side of the body.
• Interneurons prevent antagonistic muscle interference via reciprocal inhibition.
• The simplest reflexes are mediated at the spinal cord level.
• Protective structures for the brain and spinal cord include the blood-brain barrier, bones of the cranium, cranial meninges, and cerebrospinal fluid (CSF).

Muscles

• The insertion is the more movable part of a muscle.
• Isometric contractions maintain muscle length without changing shape.
• Isotonic contractions cause muscle lengthening during contraction.
• The all-or-none principle states that a muscle fiber contracts fully or not at all.
• Sprinters have a higher percentage of fast-twitch (type II) fibers than long-distance runners.
• A reflex arc sequence is: receptor response, sensory neuron signal, information processing in the CNS, motor neuron signal, peripheral effector response.
• The spinal cord ends between vertebrae L1 and L2.
• Smooth muscle is non-striated.
• To lift a heavier weight, more motor units are recruited, not individual fibers contracting harder.
• Large motor units are involved in generating power.
• Creatine phosphate replenishes ATP in the first few seconds after muscle activity begins.
• Postural (slow-twitch) muscles, like the soleus, have more myoglobin than phasic (fast-twitch) muscles, like the gastrocnemius.
• The external intercostal muscles elevate the ribs during breathing.
• The hamstrings (biceps femoris, semimembranosus, semitendinosus) flex the knee, while the quadriceps group (rectus femoris, vastus medialis, vastus lateralis, vastus intermedius) extends it.
• The triceps brachii is the primary extensor of the elbow.
• Resting membrane potential is -70 mV, depolarized is +30 mV, and hyperpolarized is < -70 mV
• Myelinated nerves transmit signals faster than unmyelinated nerves.
• The tip of the spinal cord is called the conus medullaris.
• An innate reflex is a reflex you are born with, not learned.
• A polysynaptic reflex uses one or more interneurons.
• Eccentric contractions are more likely to cause muscle damage like delayed-onset muscle soreness.
• Intercalated discs are unique to cardiac muscle.
• Cranial nerves travel directly to and from the brain.
• Microglia are the immune system of the CNS.
• Myelin is predominantly made of fat.
• The tibialis anterior dorsiflexes the foot.
• The rhomboids are not a rotator cuff muscle.
• The biceps femoris is not part of the quadriceps group.
• The deltoid muscle abducts the humerus.
• Creatine phosphate acts as an energy reserve, replenishing ATP, and is produced during both rest and exercise.
• The repeating unit of a skeletal muscle fiber is the sarcomere.

Test your knowledge on the fundamental concepts of the nervous system, including the somatic nervous system, glial cells, neurotransmitters, and neuron function. This quiz is perfect for students studying biology or neuroscience and covers key terms related to sensory neurons and synapses.