Human Biology: Exploring the Structure and Functions of the Stomach

This assignment provides detailed answers to audio response questions regarding the human stomach. It begins by describing the stomach's name, structure, and functions, including its division into cardia, fundus, body, and pylorus, along with the cell types and tissue layers within each region. The assignment then explains how the stomach integrates with other organs in the digestive system, such as the esophagus and small intestine, to perform key functions like food breakdown and nutrient absorption. Furthermore, it outlines the stomach's contribution to homeostasis, detailing its role in nutrient balance and hormone secretion. Finally, the assignment explores the stomach's self-regulation and how it is regulated by other organs, including the nervous system and hormonal mechanisms, such as the control exerted by sphincters and the secretion of gastric juices.

Running head: Audio Response Questions 1
Audio Response Questions
Name
Institution of Affiliation

Audio Response Questions 2
Question 1. Describe the name, structure and functions /roles of the stomach.
 Cell types, tissues layers and functions
The stomach is a mixed gland and secretes hormone gastrin that contains digestive enzymes.
It is divided histologically into four parts: Body, cardia, fundus, and pylorus. Food enters the
stomach in the cardia region. The body lies between the fundus and pylorus, while else the
fundus is located just above the gastroesophageal sphincter, (Hopperdietzel et al., 2014). The
Stomach lumen has rugae, which are a series of ridges that allow the stomach to expand and
accommodate more food. Body and fundus have secretory chief cells that secrete HCL. Cardia
has mucous neck cells that secrete mucus that protects the stomach lining from corrosion. Pyloric
region secretes mucus. Mucosa and submucosa layers are found within rugae muscularis cross-
linked with a network of blood capillaries. Cardia also contains simple or branched tubular
glands. The gastric gland contains the following cells: Surface mucus Stem cells, mucus neck
cells, mucus parietal (oxyntic cells), HCL Chief Cells, pepsinogen Enteroendocrine cells: gastrin
and serotonin, (Bussolati et al., 2013).
Question 2 Describe how the stomach integrates with the other organs of the same system
to perform key functions.
For proper functioning of the digestive system, the stomach has to integrate with the
other organs and tissues. This is achieved by the following: At the edge of the esophagus, there is
a valve known as a sphincter that allows food to proceed into the stomach while at the same time
close to prevent food or fluid from flowing back up the gullet, (Fox & Fox, 2015). The stomach
muscles breakdown further, churn and mix the food with digestive juices containing enzymes
and acids. This ensures the food particles that will enter the small intestine are smaller enough in
size to go through the small intestine lumen. The stomach secretes hormones that control food
intake and digestion. Food in the stomach is processed into chyme, thick liquid, and ready to exit

Audio Response Questions 3
the stomach. At the end of the stomach, there is also a muscular ring known as pylorus which
keeps the chime in the stomach until it is ready to leave the stomach. The chyme is then expelled
into the small intestine for further downstream digestion, (Denbow, 2015).
Question 3 Describe the key homeostatic elements or secretions that the stomach is
associated with and explain how it contributes to homeostasis.
Homeostasis is the mechanism the body uses to maintain the internal body process within
stable normal ranges, (Müller et al., 2018). The stomach contributes towards maintaining
homeostasis by breaking down food. This has a role in maintaining a balance of nutrients in our
body. As suggested the stomach is a mixed gland and secretes several hormones e.g. gastrin that
control food intake (satiety) and digestion, (Sherwood, 2015). Food substances such as fat-
soluble compounds will be absorbed into the systemic circulation at the stomach depending on
their blood levels. Substances such as metallic ions and water enter the bloodstream while chime
proceeds into the small intestine. Generally, absorption of molecules in the stomach does not
vary depending on body needs, however, intake of essential metal ions such as calcium and iron
is controlled according to the body's current homeostatic needs as the absorbed nutrients must
contain molecules to maintain the composition of body fluids, (Karasov et al., 2011).
Question 4 Explain how the stomach self regulates or is regulated by another organ.
Regulation of actions taking place in the stomach is achieved by the following: The
stomach has two muscular valves at its both ends; cardiac and pyloric sphincter which control
the movement of food in and out of the stomach, (Svihus, 2014). The digestive activity of gastric
juice in the stomach is regulated by hormonal and nervous mechanisms. Both mechanisms are
stimulated by the movement of food in the gut. For instance secretion of gastric juice by the
gastric glands is stimulated by the action of the parasympathetic nervous system when food
enters the stomach. As well as food exits the stomach into the small intestines, the sympathetic

Audio Response Questions 4
nervous system is activated to initiate activities that inhibit the action of the gastric gland and
gastric hormone. Also, this mechanism stimulates the release of intestinal gastrin which inhibits
further actions of gastric juice. The stomach also auto-regulate itself when food enters by
regulating the secretion of HCL and mucus from respective cells (distention of the stomach),
(Grossman, 2012).

Audio Response Questions 5
References
Bussolati, G., Papotti, M., Sapino, A., Gugliotta, P., & Macri’, L. (1988). Myoepithelial and
endocrine differentiation in breast carcinoma. Breast Cancer: Scientific and Clinical
Progress, 158-173.
Denbow, D. M. (2015). Gastrointestinal anatomy and physiology. Sturkie's Avian
Physiology, 337-366.
Fox, & Fox, S. I. (2015). Human physiology.
Grossman, M. (2012). Cellular basis of chemical messengers in the digestive system.
Elsevier.
Hopperdietzel, C., Hirschberg, R. M., Hünigen, H., Wolter, J., Richardson, K., & Plendl, J.
(2014). Journal of Fish Biology, 85(5), 1707-1725.
Karasov, W. H., Martínez del Rio, C., & Caviedes-Vidal, E. (2011). Ecological physiology
of diet and digestive systems. Annual Review of Physiology, 73(1), 69-93.
Müller, M. J., Geisler, C., Heymsfield, S. B., & Bosy-Westphal, A. (2018). Recent advances
in understanding body weight homeostasis in humans. F1000Research, 7, 1025.
Sherwood, L. (2015). Human physiology: From cells to systems. Cengage Learning.
Svihus, B. (2014). Function of the digestive system. Journal of Applied Poultry Research,
23(2), 306-314.