3M-A The Nervous System: Structure, Function, Perception, and Coordination

The Nervous System

• A complex network that enables an organism to interact with its surroundings and controls many mechanisms inside the body.
• It allows communication with the outside world and within the body.

Structure of the Nervous System

• Central Nervous System (CNS):
  • Brain: the most complex part of the human body, source of humanity.
  • Spinal cord: spinal column with 33 vertebrae and 31 spinal nerves.
• Peripheral Nervous System (PNS):
  • Nerves: autonomic and somatic.

Cerebral Hemispheres

• Structure:
  • Right and left hemispheres divided by longitudinal fissure, cerebral fissure, median longitudinal fissure, or interhemispheric fissure.
  • Connected by the corpus callosum.
  • Each hemisphere further subdivides into frontal, parietal, occipital, and temporal lobes.
• Function:
  • Thinking, perceiving, processing, and understanding languages.

Nervous Tissue

• Composition:
  • Gray matter: contains neuron cell bodies, glial cells, axon tracts, neuropil, and capillary blood vessels.
  • White matter: contains myelinated axons, glial cells, and capillary blood vessels.
• Location:
  • Gray matter: brain and spinal cord.
  • White matter: deeper areas of the cerebrum and cerebellum.

Diseases

• Neural diseases:
  • Paralysis, muscle weakness, and tingling sensations.
  • Neurodegenerative diseases: Frontotemporal dementia, Alzheimer's disease, Parkinson's disease.
• Myelin-related diseases:
  • Multiple sclerosis: demyelination of axons.

Impulse Transmission

• Nerve Impulse/Action Potential:
  • Electrical signal that conveys information along a neuron.
  • 3 processes: polarization, depolarization, and repolarization.
• Cells of the Nervous System:
  • Neurons: provide structural/functional units of the NS, transmit impulses.
  • Neuroglia/Glial cells: provide nourishment, protection, and support to neurons, do not conduct nerve impulses.

Research

• Neurogenesis:
  • Formation of new neurons by cell division in the mature human brain is limited.
  • Hippocampus produces 700-1,500 new neurons daily.
  • Brain health: 120-150 minutes of moderate-intensity exercise per week is beneficial.

Types of Neurons

• Sensory/Afferent neurons: carry nerve impulses from sensory receptors to the CNS.
• Motor/Efferent neurons: carry nerve impulses from the CNS to muscles and glands.
• Interneurons: carry nerve impulses between sensory and motor neurons.

The Five Basic Senses

• Sense of Sight: photoreceptors (rods and cones).
• Sense of Taste: gustatory receptors (sweet, sour, salty, bitter, umami).
• Sense of Touch: tactile receptors (mechanoreceptors, thermoreceptors, nociceptors).
• Sense of Hearing: mechanoreceptors (hair cells).
• Sense of Smell: olfactory receptors (camphoraceous, musky, floral, pepperminty, ethereal, pungent, putrid).

Sensory Receptors

• Specialized areas:
  • Detect specific stimuli (e.g., touch, light, sound, chemicals).
  • Found in sensory neurons.
• Types of sensory receptors:
  • Chemoreceptors (e.g., taste, odor).
  • Nociceptors (e.g., pain).
  • Proprioceptors (e.g., body position and movements).
  • Mechanoreceptors (e.g., balance, touch).

Perception and Coordination

• Perception: ability to recognize objects with the use of special senses.
• Coordination: ability to perform skilled motor acts.
• Sense of Touch: important for perception and coordination.

Test your knowledge on the structure, function, relation to perception, and coordination of the nervous system. Explore topics like cerebral hemispheres, impulse transmission, sensory receptors, and the basic senses.