Untitled Quiz

Nervous System 2 Lecture Summary

• The nervous system receives stimuli and coordinates activities of other organ systems.
• The central nervous system (CNS) includes the brain and spinal cord, responsible for information processing and control.
• The peripheral nervous system (PNS) consists of peripheral nerves and connects the CNS to other systems.
• The nervous system has subdivisions: the central nervous system (CNS) and the peripheral nervous system (PNS).
  • The CNS includes the brain and spinal cord, coordinating the activities of other organ systems.
  • The PNS includes sensory and motor divisions, connecting the CNS with sensory input receptors and motor effectors (muscles/glands).
  • The sensory division brings information to the CNS, and the motor division carries information away from the CNS.
  • Further PNS divisions include visceral and somatic, conveying sensations and actions related to internal organs or voluntary movements.
  • Sympathetic and parasympathetic divisions are further subdivisions of the autonomic nervous system, controlling internal organ function.

Early Nervous System Development

• Early development of the nervous system involves the formation of a neural plate from the ectoderm.
• The neural plate develops into a neural groove and then a neural tube.
• The neural tube is the precursor to the central nervous system (CNS), surrounding the neural cavity.
• The neural crest is formed at the edges of the neural plate and contributes to the peripheral nervous system (PNS).

Brain Development

• Brain development begins with three primary vesicles: the prosencephalon, mesencephalon, and rhombencephalon.
• These develop into additional structures and regions (e.g., telencephalon, diencephalon, midbrain, metencephalon, myelencephalon).
• Expansion and flexures (bends) shape the developing brain.
• Development continues, with specific areas emerging or growing.
  • This leads to distinct regions for different functions.
  • Examples are cerebral hemispheres, the cerebellum, midbrain, pons, and medulla oblongata.

Cranial Nerves

• Cranial nerves develop and connect peripheral receptors to the brain and coordinating motor responses.
• Development of nerves links sensory ganglia to the brain to regulate skeletal muscles functions.
• Several cranial nerves are responsible for cranial sensations and actions.

Medulla Oblongata

• The medulla oblongata is a vital part of the brainstem.
• It has relay centers (e.g., gracile nucleus, cuneate nucleus, solitary nucleus, and olivary nucleus).
• It controls vital functions like respiration and cardiovascular activities.

Pons

• Pons is a part of the brainstem.
• It contains more cranial nerves (e.g., CN V, VI, VII, VIII).
• It contains centers that control certain aspects of respiration.

Mesencephalon (Midbrain)

• This mid-level region houses important structures (e.g., superior and inferior colliculi, substantia nigra, red nucleus).
• Control of sleep-wake cycles, pain, motivation, and alertness is part of its functions.

Diencephalon

• The diencephalon is involved in sensory relay, hormones, and autonomic responses.
• It contains the thalamus with relay centers, and the hypothalamus with regulatory and control functions.

Cerebellum

• The cerebellum is crucial for fine motor control and coordination.
• It coordinates movement through connections to the cortex, and coordinates complex movements.

Cerebrum

• The cerebrum controls complex cognitive functions (e.g., thinking, speech, and decision-making).
• It has distinct lobes (frontal, parietal, temporal, and occipital) with specializations for specific functions.
• Deep structures, like basal nuclei, play a key role in controlling movement and other processes.

Somatic Nervous System

• The somatic nervous system involves things you consciously control.
• Sensory information comes from the skin, skeletal muscles, joints through afferent nerves. Signals are moved to the periphery of the body by efferent nerves.
• Somatic peripheral nerves are single-neuron systems.

Autonomic Nervous System

• The autonomic nervous system regulates bodily functions unconsciously (example: controlling heart rate and digestion).
• Motor fibers regulate visceral functions (internal organs).
• The autonomic nervous system is a two-neuron system.
• Two divisions (sympathetic and parasympathetic) often have opposite effects or functions.

Special Senses

• Olfaction (smell): Specialized organs detect scent molecules.
• Gustation (taste): Specialized taste organs detect chemical flavors in the oral cavity.
• Vision: The eye consists of three layers (fibrous, vascular, and inner layer) with specialized receptor cells capturing light to transmit information.
• Hearing: Structures filter and transmit sound waves, to receptors that detect vibrations to send to the brain.
• Balance: Sensory systems in the inner ear detect head movement related to balance.

Afferent Signal Start

• Sensory receptors detect stimuli like temperature, pain, pressure, vibration, smell, taste, balance, hearing, and vision.
• Activation of the sensory receptor generates electrical impulses in the corresponding sensory nerve.

General Senses

• Sensory receptors grouped into exteroceptors, proprioceptors, and interoceptors based on stimuli source (external, body position, or internal environment).
• Sensory receptors like nociceptors, thermoreceptors, mechanoreceptors, and chemoreceptors detect specific stimuli. Receptors have specific areas for monitoring.

Sensory Receptors' Specificity

• Sensory receptors monitor specific locations in the body.
• The receptive field size affects the precision of the location detection (smaller fields mean greater precision).