GIT 1 Flashcards
What is the GIT?
A complex system from the mouth to the anus
State the functions of the GIT
-digesting and absorb the substances we ingest and eliminate the waste
Enteric motility- activity of smooth muscle to move substances through GIT
Secretions- enzymes and fluid for digestion, mucus to transport/absorption
Digestion- chemical breakdown of ingested food into absorbable molecules
Absorption -movement of nutrient, water and electrolytes into the cell and then blood
What is the order of the main functions do occur in the GIT?
Ingestion—> digestion and absorption —>
Explain the overall function of the GIT
To absorb nutrients, electrolytes and water and eliminate waste products
Mechano- and chemo receptors respond to: Stretch, osmolarity and pH; presence of substrate and end products of digestion. They initiate reflexes that activate or inhibit certain digestive glands. Physiological processes to achieve these include motility, secretion of digestive juices, digestion of food, absorption of digestive products and fluids, the circulatory system to carry the absorbed substances away and the control of all these functions by the nervous and hormonal systems
Most food is taken in as solids and as macromolecules…
That cannot be readily transported across the intestinal epithelial cells. Digestion which involves physical and chemical alterations of the foo$ occurs first. This is facilitated by secretions from the G.I. tract and associated organs
What is mechanical disruption and when does it begin?
Mechanical disruption of ingested food begins in the mouth with chewing (mastication). Individuals without teeth usually require their solid food to be cut into smaller pieces before eating. The mechanical processes that alter food composition to facilitate composition absorption continue in the stomach both to initiate protein and lipid enzymatic digestion and to allow passage of gastric contents through the pylorous into the duodenum. This change in the size and consistency of gastric contents is necessary because solids that are greater than 2 mm in diameter do not pass through the pylorous
Why are a complex series of chemical reactions unique to each nutrient?
The chemical form in which different nutrients are ingested and absorbed varies according to the specific nutrient in question. Thus, complex series of chemical reactions are required to convert macromolecules into respective micronutrient
Explain digestion requiring enzymes secreted in the mouth, stomach, pancreas, and small intestine
Digestion involves the conversion of dietary food nutrients to a form that the small intestine can absorb. Digestion is completed in the small intestine by the action of enzymes. Digestion by these brush border enzymes is referred to as membrane digestion. The material presented to the small intestine includes both dietary intake and secretory products. The food material entering the small intestine differs considerably from that of the ingested material because of the mechanical and chemical changes just discussed. The load to the small intestine is also significantly greater than that of the ingested material. Dietary fluid intake is 1.5 to 2.5 L/day, whereas the fluid load presented to the small intestine is 8 to 9 L/day. The increased volume results from substantial quantities of salivary, gastric, biliary, pancreatic, and small intestinal secretions. These secretions contain large amounts of protein, primarily in the form of the digestive enzymes.
What happens after nutrients are metabolized?
Through a series of chemical processes- making it possible for cells to continue living. Waste substances from the ingested food are stored and excreted in the G.I. tract. Also excreted in the G.I. tract are products from the liver such as bile acids formed from cholesterol, bile pigments formed from hemoglobin degradation and drug metabolites
What is the function of the mouth?
Salivary enzymes begin carbohydrates digestion and breaking up of food particles
What is the function of salivary glands?
Moistens and lubricates food. The enzyme amylase digests carbohydrates
What is the function of the pharynx?
Directs food into the stomach to prevent choking
What is the function of the esophagus ?
Carries food down from the mouth to the stomach
What is the function of the liver?
The largest organ inside of the body. Makes bile (fluid that helps break down fats and gets rid of wastes in the body;); changes food into energy; and clears alcohol, some medicines, and poisons from the blood . Stores vitamins and iron. Destroys old blood cells
What is the function of the stomach?
Secretes hydrochloric acid and gastric juice and activates enzymes, continues to kill bacteria and pathogens. Stores and churns food. Enzyme pepsin digests protein
What is the f7nctio; 9f the gall bladder?
Stores the bile made in the liver, then empties it into the small intestine to help digest fats. Stones can form within.
What is the function of the pancreas?
A gland that makes enzymes for digestion and bicarbonate to neutralize stomach acid. Also makes the hormone insulin, which helps the body turns food into energy, and regulates blood sugar levels
What is the function of the small intestine ?
Digests protein, fats and carbs. Bacterial metabolism plus nutrient and excess water absorption. Surface is covered in villi for greater absorption. Site of fructose malabsorption and coeliac disease.
What is the function of the large intestine?
Also called the colon. It absorbs water and electrolytes from stool. It also contains beneficial bacteria which help produce certain vitamins. Forms and stores feaces
What is the function of the appendix?
A pouch attached to the first part of the large intestine. No one knows it’s function
What is the function of the rectum?
The lower end of the large intestine, leading to the anus. Stores and expels faeces
What is the function of the anus
The. Opening at the end of the digestive tract where the bowel movements leave the body
Explain the secretions and motility patterns of the oral cavity and esophagus
Motility patterns: swallowing, chewing
Secretions: saliva(salivary glands)
Digestion: carbohydrates, fats(minimal)
No absorption
Explain the motility pattern, secretion and digestion of the stomach
Motility pattern: peristaltic mixing and propulsion
Secretions: HCl (parietal cells); pepsinogen and gastric lipase (chief cells ) ; mucus cells and HCO3- (surface mucous cells); gastrin (G cells) ; histamine( ECL cells)
Digestion: proteins, fats
Absorption: lipid-soluble substances such( as alcohol and aspirin )
Explain the motility patterns, absorption, digestion of the small intestine
Motility pattern: mixing and propulsion primarily by segmentation
Secretion: enzymes; HCO3- and enzymes (pancreas) ; bile (liver) ; mucus(goblet cells ); hormones : CCK, secretin, GIP, and other hormones
Digestion: carbohydrates, fats, polypeptides, nucleic acids
Absorption: peptides by active transport; amino acids, glucose, and fructose by secondary active transport ; fats by simple diffusion; water by osmosis; ions, minerals, and vitamins by act8ve transport
