About Lesson
Hunger contractions, Thirst and Vomition
- Hunger contraction
The strong contraction of stomach which is felt when stomach is empty for longer period of time
Causes for hunger
- Empty stomach for longer period
- Lack of nutrients in small intestine
- Hormone like Ghrelin and Leptin
- Endorphin and Dopamine
Hypothalamus decides whether we are feeling hunger or full. When we are hungry our body is low in energy. So, we have decreasing Glucose concentration in blood and decrease in lipid level.
- Thirst
- Strong desire to drink fluids/water.
- Initiated when fluid loss within/ from osmoreceptors (specialized brain cells) and outside from cells
- Vomition
- Forceful expulsion of gastrointestinal contents through mouth
Causes:
- Irritation/ infection
- Food poisoning
- Indigestion etc.
Physiology
- Vomitting center contains receptors which triggers vomiting reflex
- another area near vomiting center, there is chemoreceptor trigger zone (CTZ)
- When CTZ is stimulated, this stimulates vomiting center
- Similarly, during motion sickness, inner ear (balance center) send signal to brain stem through vestibulo-cochlear nerve in vestibular nuclei and this signal is then passed to CTZ then to Vomiting center which triggers vomiting reflex.
From higher brain center (cerebrum), signal travel to vomiting center and trigger vomiting reflex.
Vomiting reflex
- Contraction of abdominal muscles and Diaphragm and relaxation of lower oesophageal sphicther
- Increases abdominal pressure
- Thus expulsion of contents(GI) occurs