Physiology and Function in Human Term Paper

Excerpt from Term Paper :

Therefore, in cases unrelated to ileocecal valve malfunction, large distal bowel obstruction is a direct function of LaPlace's Law at the area of the cecum. For the same mechanical reason, the most frequent location of colonic perforation is also at the cecum because it is the area of the largest diameter, and therefore, most susceptible to rupture in comparison to areas smaller in diameter.

11. What are the major types of movement of small intestine?

The first major type of movement in the small intestine is peristalsis. The second major type of movement in the small intestine are discrete clustered contractions, which are comparatively small movements. The third type of major movement in the small intestine is giant migrating contractions, which are larger versions of peristaltic contractions believed to serve a bacterial cleansing purpose.

12. Describe gastric acid feedback function

Gastric acid feedback is controlled by nerve endings in the stomach that are sensitive to acetylcholine and gastrin-release peptide. Gastrin and acetylcholine both stimulate the production of gastrin. High levels of gastrin trigger the release of somatostatin and histamines, both of which then inhibit further release of gastrin through their effects on the parietal cells.

13. Describe trypsin, lipase, and amylase biological function

Trypsin released into the duodenum is important for the breakdown of peptides through hydrolyses. By breaking down proteins into their constituent amino acids, trypsin facilitates the absorption of sufficiently small molecules to pass through the membranes of the small intestine. Lipase is a digestive enzyme produced by the pancreas and is essential to the breakdown of lipids into fatty acids. During the digestion of lipids, lipase breaks the complex bonds of triglycerides into less complex monoglycerides for absorption. The enzyme amylase breaks down sugars and starches in the process of converting them into glucose for storage in the liver and the skeletal muscles. This process begins with the amylase within saliva in the mouth and continues in the intestines through amylase produced by the pancreas.

14. What hormones control gastrointestinal motility?

The hormones that control gastrointestinal motility are gastrin, secretin, and cholecystokinin.

15. Describe stomach nervous myenteric plexus, what condition will occur if it is dysfunctional?

Stomach nervous myenteric plexus is a component of the enteric nervous system that originates in the medulla oblongata and the vagus nerve. It is responsive to both sympathetic and parasympathetic impulses and is crucial for normal regulation of intestinal motility. Disruption in the impulses carried by the stomach nervous myenteric plexus results in severe impairment of intestinal motility and can cause chronic intestinal pseudo-obstruction.

16. What are the saliva's functions? Why can saliva inhibit bacteria growth?

Saliva is essential to the swallowing reflex because it both lubricates the tissues of the esophagus and also initiates the creation of bolus. Saliva also begins the digestive process, particularly of sugars and starches through the enzyme amylase. Saliva has antibacterial properties that may inhibit bacterial growth but also limits the buildup of anaerobic bacteria by keeping the surfaces of the mouth wet and preventing the accumulation of bacteria such as those typically responsible for halitosis.

17. Describe movements of the colon What is Haustration and what is its significance for defecation?

Generally, movement of bolus in the colon and the conversion of bolus into feces is stimulated by the presence of food matter that is ingested and the measure of contraction is a function of the size (and content) of the food. Greater amounts of food produce larger movement in the colon. The presence of matter in the colon stimulates the relaxation of the sphincter muscles as provides a signal to defecate. Haustration is the process of mixing the feces to maximize its exposure to the intestinal walls to ensure optimal water absorption by the large intestine and the colon. The significance of Haustration to defecation is that the process is necessary to produce a formed stool capable of stretching the colon to initiate the process through nerve stimulation of the anus.



Sources Used in Document:


Iazzetti, G., and Rigutti, E, (2007). Atlas of Human Anatomy. London, UK: TAJ Books


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