Nervous System & Brain Structures

Nervous System

• An extensive network of specialized nerve cells, coordinates the body's functions.
• Neuroscience studies the structure and function of neurons and nerves.

Brain Structures

• The brain has six major structures: cerebrum, cerebellum, diencephalon, midbrain, pons, and medulla oblongata.

Cerebrum

• The largest part of the brain.
• Controls the five senses and most conscious activities.
• Consists of left and right hemispheres.

Lobes of the Cerebrum

• Frontal lobe: Controls attention, intelligence, and behavior.
• Parietal lobe: Processes sensory information.
• Temporal lobe: Responsible for memory.
• Occipital lobe: Processes visual input.

Cerebellum

• Also known as the "little brain."
• Responsible for muscle coordination and balance.
• Plays a crucial role in motor control.

Diencephalon

• Contains the thalamus and hypothalamus.
• Regulates visceral activities like appetite, thirst, and sexual behavior.
• Thalamus acts as a relay station for sensory information.
• Hypothalamus maintains homeostasis.

Midbrain

• Connects the diencephalon and cerebrum with the pons.
• Plays a crucial role in motor movement, vision, hearing, and alertness.

Pons

• Located below the midbrain.
• Involved in tasting and saliva production.
• Responsible for reflex actions.

Medulla Oblongata

• The lowest part of the brainstem, connects to the spinal cord.
• Controls sneezing, coughing, and blood pressure.
• Known as the center for respiration.

Spinal Cord

• Links the brain to the nerves in the rest of the body.
• Has four regions: cervical, thoracic, lumbar, sacral, and coccygeal.
  • Cervical (C1-C7)
  • Thoracic (T1-T12)
  • Lumber (L1-L5)
  • Sacral (S1-S5)
  • Coccygeal (C1-C5)

Peripheral Nervous System

• Connects the brain and spinal cord to the rest of the body.
• Has two divisions: somatic and autonomic nervous systems.

Somatic Nervous System

• Controls voluntary movements.
• Consists of cranial nerves (12 pairs) and spinal nerves (31 pairs).

Autonomic Nervous System

• Controls involuntary functions.
• Includes the sympathetic nervous system (fight or flight) and parasympathetic nervous system (rest and digest).
• Relays impulses to involuntary organs and smooth muscles.

Enteric Nervous System

• Manages digestion.

Neuron Structure and Function

• Neuron is the basic cell of the nervous system.
• Dendrites receive chemical messages (neurotransmitters).
• Soma (cell body) maintains the cell.
• Axon hillock generates an electrical charge.
• Axon is a tubelike structure transmitting signals.
• Myelin sheath is a fatty substance insulating the axon.
• Nodes of Ranvier facilitate chemical messages.
• Axon terminals are enlarged ends of axonal branches.

Synaptic Neurotransmission

• The process by which neurons communicate or pass information.
• Synaptic vesicles are saclike structures containing neurotransmitters.
• Synapse (synaptic gap) is the fluid-filled space between neurons.
• Reuptake is the process where neurotransmitters are taken back into synaptic vesicles.

Neuron Potentials

• Resting potential: The state of a neuron when not firing a neural impulse.
• Action potential: The release of a neural impulse due to a reversal of electrical charge within the axon.
• +40 is Depolarization.
• -55 is the Threshold.
• -70 is the Resting Potential.