Gastritis Causes and Types

Gastritis

• Inflammation of the gastric mucous membrane, which can be acute or chronic.
• Acute gastritis involves inflammation of the superficial layers of the mucous membrane and infiltration with leukocytes, primarily neutrophils.
• Chronic gastritis involves inflammation of the deeper layers and infiltration with more lymphocytes.

Causes of Gastritis

• NSAIDs (Non-Steroidal Anti-Inflammatory Drugs)
• Alcohol
• Factors that increase peptic activity
• Bacterial, viral, and traumatic causes (e.g., nasogastric tubes)
• Chronic gastritis is often caused by the bacterium Helicobacter pylori

Gastric Atrophy

• Result of chronic gastritis
• Characterized by the shrinkage and weakening of the stomach muscles and glands
• Leads to a deficiency of gastric juice
• Also known as Chronic Gastric Atrophy

Peptic Ulcer

• Erosion of the surface of an organ due to the shedding of inflamed necrotic tissue
• Can occur in the stomach (Gastric ulcer) or duodenum (Duodenal ulcer)
• Caused by the digestive action of gastric juice

Sensory Nervous System

• The sensory system starts from receptors, which are detectors of any changes in the body.
• Receptors are connected to dendrites, located in the dorsal spinal ganglia.
• The sensory information is transmitted to the spinal cord, CNS, and finally interpreted in the somatosensory cortex.

Types of Somatosensory Receptors

• Mechanoreceptors:
  • Tactile receptors (touch, pressure)
  • Proprioceptors (muscle spindle, Golgi tendon organ, joint capsule receptors)
  • Nociceptors
• Thermoreceptors:
  • Cold receptor (Ad fibre): 10°C to 40°C, peak 24°C
  • Warm receptor (C fibre): 30°C to 49°C, peak 45°C
  • Heat nociceptor (Ad fibre): stimulated when temp >45°C
  • Cold nociceptor (C fibre): stimulated when temp < 5°C
• Chemoreceptors: smell, taste, and osmoreceptors (detect gases in the blood)
• Photoreceptors: rods and cones (electromagnetic receptors)
• Polymodal Receptors: nociceptors – C fibers

Tactile Receptors

• Pacinian Corpuscle: the most sensitive mechanoreceptor in the somatosensory system
• Meissner's Corpuscle: the most numerous tactile receptor in the hand, with a density of approximately 2 per mm at the fingertip
• Receptive Fields: smallest on the fingertips, averaging 11 mm for Merkel's cell fibers and approximately 25 mm for Meissner's corpuscle
• Tactile Acuity: slightly greater in women than in men, and varies between fingers but not between hands

Nociceptors and Thermoreceptors

• Nociceptors: mediate pain, can be stimulated by mechanical, thermal, and chemical stimuli
• Polymodal Nociceptors: can respond to different modalities of stimuli
• Fast Pain: elicited by mechanical and thermal stimuli
• Slow Pain: can be elicited by all three types of stimuli
• Nociceptors Location: on the ending of nociceptive nerve (free nerve ending) that mediates pain and temperature (Ad and C fibers)
• Transient Receptor Potential Channel (TRP): an ion channel that mediates nociceptors, with at least 6 types of TRP

Notes for Remembering

• In the human body, there are 3 to 10 times more cold spots (receptors) than warmth spots
• Maximum cold spots are present in the lips (15 to 25 cold spots/cm2), 3 to 5 in the finger, and less than 1 cold in some areas of the trunk