ch 4-6 Flashcards
List the primary and accessory components of the GI tract.
The primary components are the mouth, pharynx, esaphogus, stomach, small and large intestine, & anal canal. The accesory components are the teeth, tounge salivary glands, liver, gallbladder, and pancreas.
What is a sphincter?
thickened regions of circular muscle that control the flow of contents at various points in the GI tract
Why are sphincters important for the function of the GI tract?
help control rates of digestion and absorption ; blood is supplied to organs through splenic circulation
Explain the difference between mechanical and chemical digestion.
Mechanical : the physical break down of food as it goes down the Gi tract
Chemical: the breakdown of large nutrient molecules in food into smaller components, primarily by the action of stomach acid and various enzymes, proteins that allow chemical reactions to occur at a rapid rate
Describe the lining of the wall of the GI tract.
called the mucosa, which consists of a layer of epithelium directly facing the lumen, a connective tissue layer called the lamina propria, and a thin layer of smooth muscle known as the muscularis mucosae
Explain what normally happens to food once it enters the mouth.
food is masicated (chewed) then mixed with salivary glands which moistens the food and begins the chemical breakdown into carbohydrates, then the tounge turns food into bolus and goes down the throat
key components of saliva
sodium, potassium, calcium, magnesium, bicarbonate, and phosphates.
the taste sensations that human taste buds detect.
sweet, sour, salty, bitter, savory
Discuss disorders of taste and smell, including their causes
. Disorders of smell : Anosmia- caused by age advancement, brain tumors, dental disease , nose problems
Disorders of taste: hypogeusia (diminished ability to taste), Aguesia ( complete inability to taste) - caused by poor dental health, head injuries and ear infections
Peristalsis
waves of muscular contractions that help move material ; After being swallowed, the food bolus travels through the esophagus
the key function of the epiglottis and what would happen if the epiglottis was not working properly
a flap of tough tissue that prevents the food from entering the larynx and trachea.
Under normal circumstances, what keeps stomach contents from reentering the esophagus
the lower esophageal sphincter (LES)
the four different gastric gland cells and list their secretions.
mucous cells, Parietal cells , chief cells, G cells
Describe the digestive processes that occur in the stomach.
food in the stomach stimulates peristalsis which mixes food with gastric juice (some protein and fat are broken down)
how the stomach protects itself from digestion. What conditions might occur if this protection fails
The stomach lining secretes mucus to protect itself. If this fails, ulcers can form
List factors that influence stomach emptying.
Meal composition, hormonal signals, and nervous system inputs
List the three primary sections of the small intestine and identify where most nutrient digestion and absorption occurs
Duodenum, jejunum, and ileum. Most nutrient digestion and absorption occur in the jejunum.
Where is bile synthesized and stored?
Bile is synthesized in the liver and stored in the gallbladder.
Explain the importance of the pancreas as an accessory organ for nutrient digestion
The pancreas produces digestive enzymes and bicarbonate to neutralize stomach acid in the small intestine.
Discuss the three major gut hormones, including the tissues from which they are released, the factors causing their release, and their key actions.
Gastrin (released from the stomach), Secretin (released from the small intestine), and Cholecystokinin (CCK, released from the small intestine).
Explain how the structure of villi increases the surface area available for absorption
Villi are finger-like projections that increase surface area for absorption in the small intestine.
Identify the five ways that nutrients can be absorbed by enterocytes.
Passive diffusion, facilitated diffusion, active transport, endocytosis, and paracellular transport.
the dietary and physiological factors that affect nutrient bioavailability
Dietary factors include the presence of other nutrients and anti-nutrients. Physiological factors include age, health status, and enzyme activity.
List the main sections of the large intestine from the ileocecal sphincter to the anus.
The main sections of the large intestine are the cecum, colon (which includes the ascending, transverse, descending, and sigmoid colon), rectum, and anus.
primary function of the large intestine
The primary function of the _
———- is to absorb water and electrolytes from indigestible food matter and to store waste until it is excreted.
Mouth
where food is chewed and mixed with saliva for digestion.
Esophagus
a muscular tube that transports food to the stomach
Stomach
where food is mixed with gastric juices for further digestion
Small intestine
where most digestion and nutrient absorption occurs
Large intestine
where water is absorbed and waste is prepared for excretion
Rectum
stores feces until they are expelled
anus
the opening through which feces are excreted
the roles of the gut microbiota in human health
include aiding in digestion, synthesizing vitamins, protecting against pathogens, and playing a role in the immune system
probiotic
a live microorganism that provides health benefits when consumed in adequate amounts, such as Lactobacillus
prebiotic
a substance that induces the growth or activity of beneficial microorganisms, such as inulin
irritable bowel syndrome (IBS)
a common gastrointestinal disorder that affects the large intestine
Crohn’s disease
a chronic inflammatory bowel disease (IBD) that causes inflammation in the digestive tract
ulcerative colitis
primarily affects the colon and rectum and only involves the innermost lining of the bowel
What do plants need to make carbohydrates?
sunlight, carbon dioxide, and water to make carbohydrates through the process of photosynthesis.
two general categories of carbohydrates
simple; starches and
complex; fibers
Identify the major functions of carbohydrates in the body.
providing energy, serving as a source of dietary fiber, and playing a role in the structure of cells
chemical names for blood sugar, table sugar, milk sugar, and malt sugar
glucose, sucrose, maltose
glycogen and starch
Glycogen and starch are both polysaccharides that serve as energy storage in living organisms. Glycogen is primarily found in animal tissues, especially in the liver and muscles, and is more highly branched than starch. Starch, on the other hand, is the main storage form of energy in plants and consists of two components: amylose (linear) and amylopectin (branched). Both glycogen and starch are made up of glucose units, but their structures and functions differ significantly
Dietary fiber
a type of carbohydrate that the body cannot digest. It is found in plant foods and is important for maintaining digestive health. Fiber can be soluble or insoluble, with soluble fiber dissolving in water and helping to lower blood cholesterol and glucose levels, while insoluble fiber adds bulk to the stool and aids in digestion.
sources of soluble fiber
oats and beans
sources of insoluble fiber
whole grains and vegetables like carrots and broccoli.
FDA food product labeled “whole grain”
one that contains the entire grain kernel, which includes the bran, germ, and endosperm. This ensures that the product retains the nutrients and fiber found in the whole grain.
dietary fiber
In the small intestine, mostly not digested and helps to slow down the absorption of nutrients. In the large intestine, r can be fermented by gut bacteria, and helps to facilitate bowel movements.
soluble fiber
helps lower cholesterol levels and stabilize blood sugar
insoluble fiber
aids in digestion and promotes regular bowel movements.
three major classes of lipids
triglycerides, phospholipids, and sterols
Major functions of lipids in the body
energy storage, insulation, protection of organs, and serving as structural components of cell membranes
Saturated fatty acids
no double bonds between carbon atoms
monounsaturated fatty acids
have one double bond, and polyunsaturated fatty acids have two or more double bonds
omega-3 fatty acid
has its first double bond at the third carbon from the end of the carbon chain
omega-6 fatty acid
has its first double bond at the sixth carbon
Foods rich in saturated fat
butter and fatty cuts of meat
Foods rich in monounsaturated fat
olive oil and avocados
phospholipid
composed of two fatty acid tails, a glycerol backbone, and a phosphate group.
emulsifier
helps blend ingredients that typically do not mix well, such as oil and water, by reducing surface tension and stabilizing the mixture
Cholesterol
is necessary for health as it is a vital component of cell membranes, a precursor for steroid hormones, and is involved in the synthesis of vitamin D
Chylomicrons
rich in triglycerides, VLDL (very low-density lipoprotein) contains triglycerides and cholesterol, LDL (low-density lipoprotein) is high in cholesterol, and HDL (high-density lipoprotein) is rich in protein and helps transport cholesterol away from cells.
