Human Nervous System Quiz

Nervous System

• Divided into two main parts: Central Nervous System (CNS) and Peripheral Nervous System (PNS)
• CNS consists of the brain and spinal cord, while PNS consists of all nerves outside the CNS

Central Nervous System (CNS)

• Brain
  • Control center of the body, responsible for processing sensory information, regulating bodily functions, and facilitating cognitive activities
  • Uses up to 20% of the body's energy
• Spinal Cord
  • Cylindrical structure that connects the brain to the peripheral nervous system, transmitting sensory and motor information
  • Coordinates reflexes
  • Location: upper 2/3 of vertebral column, begins at level of C1 and ends at L1, with its lower end called conus medullaries
  • Cauda equina: starts at L1 to coccyx

Structure of the Spinal Cord

• Gray Matter: Inner region, composed of neuron cell bodies, dendrites, and synapses, forming an "H" or butterfly shape in cross-section
• White Matter: Outer region, composed of myelinated axons that form tracts carrying signals up and down the spinal cord

Spinal Cord Segments

• Cervical: Controls signals to and from the neck, shoulders, arms, and hands
• Thoracic: Innervates signals to and from the chest and abdomen
• Lumbar: Controls signals to and from the lower back and legs
• Sacral: Innervates signals to and from the pelvis and lower limbs
• Coccygeal: Provides innervation to a small area of the skin in the coccygeal region

Protection of the Spinal Cord

• Vertebral Column: Surrounds and supports the spinal cord
• Meninges: Three layers of protective membranes (dura mater, arachnoid mater, and pia mater) that surround the spinal cord and brain
• Cerebrospinal Fluid (CSF): Fluid-filled spaces between the meninges that cushion and support the spinal cord

Major Parts of the Brain

• Cerebrum: The largest part, responsible for higher brain functions such as thought, action, and sensory processing
• Cerebellum: Coordinates voluntary movements, balance, and posture
• Brainstem: Includes the midbrain, pons, and medulla oblongata; controls basic life functions such as breathing, heart rate, and blood pressure
• Diencephalon: Contains the thalamus and hypothalamus; the thalamus acts as a relay station for sensory information, while the hypothalamus regulates homeostasis

Peripheral Nervous System (PNS)

• Divided into:
  • Somatic Nervous System: Controls voluntary movements and transmits sensory information to the CNS
  • Autonomic Nervous System (ANS): Regulates involuntary body functions and is further divided into:
    • Sympathetic Nervous System: Prepares the body for stress-related activities ("fight or flight")
    • Parasympathetic Nervous System: Conserves energy and promotes rest and digestion ("rest and digest")

Cranial Nerves

• 12 pairs of cranial nerves, including:
  • Olfactory
  • Optic
  • Oculomotor
  • Trochlear
  • Trigeminal
  • Abducens
  • Facial
  • Vestibulocochlear
  • Glossopharyngeal
  • Vagus
  • Accessory
  • Hypoglossal

Neurons and Neurotransmission

• Neurons: The fundamental units of the nervous system, responsible for transmitting information through electrical and chemical signals
• Structure of a Neuron:
  • Cell Body (Soma): Contains the nucleus and organelles
  • Dendrites: Receive signals from other neurons
  • Axon: Transmits signals away from the cell body
  • Myelin Sheath: Insulating layer around some axons, speeds up signal transmission
  • Synapse: The junction between two neurons where neurotransmission occurs

Types of Neurons

• Sensory Neurons: Transmit sensory information from sensory receptors to the CNS
• Interneurons: Found in the CNS, they integrate and process information between sensory and motor neurons
• Motor Neurons: Transmit signals from the CNS to muscles and glands, controlling movement and secretion
• Multipolar neurons: Have one axon and many dendritic branches, carrying signals from the central nervous system to other parts of the body
• Unipolar neurons: Also known as sensory neurons, they have one axon and one dendrite branching off in opposite directions from the cell body, passing signals from the outside of the body to the CNS
• Bipolar neurons: Have one axon and only one dendrite branch, passing signals from one neuron to the next inside the CNS
• Pyramidal neurons: Have one axon and two main dendrite branches, passing signals inside the brain and telling muscles to move
• Purkinje neurons: Found in the cerebellum, the part of the brain that controls balance, coordination, and timing of actions, with one axon and a very dense and complicated dendrite arrangement