Ingestive behavior

Ingestive behavior in behavioral physiology by Sobia Iqbal

1. Ingestive behavior Ingestive behaviors encompass all eating and drinking behaviors

2. These actions are influenced by physiological regulatory mechanisms; these mechanisms exist to control and establish homeostasis within the human body. Any disruption in this action can cause eating disorder obesity, anorexia, and bulimia Initiating ingestion Body weight regulation requires a balance between food intake and energy expenditure.

3. Two mechanism to control body weight 1 increase motivation to eat 2 restrain food intake Signals from environment The environment of early humans shaped the evolution of ingestive regulatory mechanisms, starvation used to be a greater threat to survival than overeating.

4. Main social environmental factors include: People who eat in groups tend to eat more than when they are by themselves When people eat in the presence of models who eat a lot or a little, they are likely to eat similarly to the model Individuals who eat in the presence of others who they think are watching them, tend to eat less than they do when they are by themselves

5. Along with social environmental factors, ingestive behaviors are also influenced by atmospheric environmental factors. Atmospheric factors include: Package sizing: the size of the packaging tends to influence what an individual thinks is the norm for consumption Food odor: unpleasant odors are likely to decrease ingestion, while pleasant odors are likely to increase ingestion Temperature of environment: people tend to eat more in cold climates and tend to drink more in warmer climates Lighting of environment: people are more likely to stay put and eat in an environment with dim lighting rather than harsh bright

6. Signals from stomach The gastrointestinal system, particularly the stomach, releases a peptide hormone called ghrelin Here is mechanism Leptin and ghrelin mechanism From lecture

7. Metabolic signals Low level of blood glucose level

8. Feeding behavior The specialization of organisms towards specific food sources is one of the major causes of evolution of form and function, such as: mouth parts and teeth , such as in whales, vampire bats, leeches, mosquitos, predatory animals such as felines and fishes, etc. distinct forms of beaks in birds, such as in hawks, woodpeckers, pelicans, hummingbirds, parrots, kingfishers, etc. specialized claws and other appendages, for apprehending or killing (including fingers in primates) changes in body color for facilitating camouflage, disguise, setting up traps for preys, etc. changes in the digestive system, such as the system of stomachs of herbivores, commensalism and symbiosis

9. By mode of ingestion Filter feeding: obtaining nutrients from particles suspended in water e.g fishes and some species of ducks Deposit feeding: obtaining nutrients from particles suspended in soil Bacteria , fungi , arthropods like earthworms Fluid feeding: obtaining nutrients by consuming other organisms' fluids mosquitoes, leeches, aphids, spiders, tick, and a hummingbird Bulk feeding: obtaining nutrients by eating all of an organism. lions, snakes, and most bird species Ram feeding and suction feeding: ingesting prey via the fluids around it Shark

10. By mode of digestion Extra-cellular digestion: excreting digesting enzymes and then reabsorbing the products fungi , lichens Myzocytosis : one cell pierces another using a feeding tube, and sucks out cytoplasm conoid Phagocytosis: engulfing food matter into living cells, where it is digested protozoa