Digestive System & Metabolism - Exam 3 Flashcards
What are the main organs involved in digestion?
everything along the alimentary canal (gastrointestinal tract)
What does the alimentary canal include?
mouth pharynx esophagus stomach small intestine large intestine rectum
What is the alimentary canal made up of?
continuous muscular tube
What are the accessory digestive organs?
teeth tongue gall bladder salivary glands liver pancreas
What is the role of the lips in digestion?
mechanical
help break down food
What is the role of the teeth in digestion?
mechanical
chew food into smaller particles
What is the role of the tongue in digestion?
mechanical
kneads food into smoother, smaller particles
What is the role of the hard and soft palate in digestion?
mechanical
hard palate is used to knead food against
soft palate relates to gag reflex
What is the role of the epithelium and salivary glands in digestion?
chemical
both secrete saliva and enzymes that both lubricate and help break down food into easily digested and absorbed pieces
How is saliva produced?
controlled by the senses
smell, sight etc
What starts the process of digestion?
senses
What is the composition of saliva?
- mainly water
- electrolytes
- digestive enzymes
- proteins (musin)
- protective substances
- metabolic wastes
What is the average output of saliva?
1-1.5 L per day
What is another word for swallowing?
deglutition
What is the purpose of the gag reflex?
to keep food from going into the wrong places
What are the main digestive enzymes that digest the macromolecules?
protease
lipase
amylase
nuclease
What is extrinsic control?
outside wall of digestive tract
Where does extrinsic control stimuli come from?
- info obtained by CNS
- emotion, special senses
How could extrinsic control change saliva production and digestive activity?
- sights and smells can increase saliva production
- senses are what begin digestive activities
What is intrinsic control?
in wall of digestive tract
Intrinsic controls are detected by which receptors?
nerve plexuses
hormone-producing cells
What controls digestive activity?
intrinsic and extrinsic controls
What does an increase in sympathetic nervous system stimulation do to saliva production and digestive activity?
inhibits saliva production and digestive acitivities
What is the difference between segmentation and peristalsis?
- segmentation is when nonadjacent alimentary canal organs contract and relax, breaking apart and moving food forwards and backwards
- peristalsis is when adjacent segments of alimentary canal contract and relax to propel food forward
What tissue drives segmentation and peristalsis
smooth muscle tissue
muscular mucosa
What cells are responsible for the acidic environment of the stomach?
parietal cells
chief cells
What do chief cells do?
release inactive pepsinogen
What do parietal cells do?
release HCl
Where are chief and parietal cells found?
gastric pits and glands of the stomach
What happens when pepsinogen mixes with HCl?
it is converted to active pepsin
What is pepsin?
a protease
How do bile and pancreatic juices influence the chemical environment of the duodenum?
bile, pancreatic juices and chyme are mixed together through duodenum’s contractions to create a final spot for chemical break down to occur
How do bile and pancreatic juices influence digestion?
bile emulsifies fats into smaller globules to increase surface area
pancreatic juices break down every type of macro
What controls produce short and long reflexes?
intrinsic and extrinsic controls
What causes a short reflex?
chemoreceptors, osmoreceptors, or mechanoreceptors go straight to the intrinsic nerve plexus (gut brain) rather than passing through the CNS
What causes a long reflex?
External or internal stimuli passes through the CNS before being translated to the intrinsic nerve plexus
What increases waves of peristalsis?
gastrocolic reflex
What modifications are present in the digestive system that increase surface area?
villi in the small intestine dramatically increase surface area for absorption
What other part of digestion increases surface area?
bile emulsifying fats
chewing of foods
What is the path of absorption of lipids?
- fatty acids and monoglycerides enter intestines via diffusion
- fatty acids and monos are recombined to form tryglycerides and are mixed with other lipids and proteins to form chylomicrons
- chylomicrons enter the lacteals of the villi and are transported to the systemic circulation via lymph in thoracic duct
- short chain fatty acids are absorbed, move into capillary blood in villi by diffusion, and are transported to liver
Where are long-chain fatty acids transported to?
lymphatic system
Where are short and medium-chain fatty acids transported to?
cardiovascular system
blood circulation
How do we get fat out of the small intestines?
lipoproteins (chylomicron, VLDL, LDL, HDL)
What do chylomicrons do and where do they end up?
transport lipids from intestines to lymph
end in liver
Where does VLDL start, what does it do, and where does it end?
- liver after consuming saturated fats
- deposits fats around body
- circulation
Where does LDL start, what does it do, and where does it end?
- converted VLDL
- deliver cholesterol to tissues
- liver or arteries
Where does HDL start, what does it do, and where does it end up?
- liver after consuming unsaturated fats
- artery scrubber
- returns cholesterol to liver
What is found in the large intestine that helps aid in digestion and produces vitamins?
gut bacteria aids in digestion and produces vitamin K
In what portion of the GI tract does most absorption occur?
small intestines
How does the GI tract protect itself from its own digestion in the stomach and small intestines?
- bicarbonate ions neutralizes HCl in stomach
- pepsin and pepsinogen protect from self-digestion in small intestine
How is ATP generated from glucose?
Glycolysis reaction breaks down 6C glucose to 2 molecules of 3C pyruvate. Pyruvate is then converted to acetyl-CoA in the transition reaction. Acetyl. CoA enters Krebs with oxaloacetate presence, producing coenzymes that carry electrons to the ETC to produce ATP.
How are fatty acids broken down?
lingual lipase chemically breaks down large fat molecules, and bile later breaks down to micelles which later become chylomicrons
Why do fats produce more ATP than any other macromolecule?
Fat contains long carbon chains, so they have a lot of carbon to be converted to acetyl-CoA. More acetyl CoA equals more ATP generation.
In what form are simple carbs stored in the liver and skeletal muscle?
glycogen
Connect Type I diabetes to ketoacidosis and ketone bodies in the blood
Type I diabetes is characterized by the body’s inability to produce its own insulin. When insulin is not present to process glucose for energy use, the body starts to burn fat for energy, which produces ketone bodies. The buildup of ketone bodies in the blood turns blood more acidic, causing DKA.
Why are vegetarians advised to eat multiple types of vegetables to get the proper amount of protein in their diet?
Many vegetables are incomplete proteins, which means they lack 1 or more of the essential amino acids. Eating a wide range of vegetables in combination with each other will ensure that each vegetable acts as a complimentary protein, to ensure that you are receiving adequate amino acids
Can glucose be converted to and stored as fat?
yes
How is fat used in the body?
as phospholipids in cell membranes
as cushion and insulation
as a fuel source
sterols
Why are minerals important in the diet?
aid in metabolism
What is the muscular layer of the esophagus made up of?
smooth muscle
What is the enteric nerve plexus?
gut brain
What factors in the stomach create a barrier to protect against the harsh environment?
mucus (bicarbonate ions)
high turnover of cells
tight junctions
How much gastric juice is produced daily?
3 Liters
Control of gastric secretion occurs in how many phases?
3
What are the 3 phases of gastric secretion control?
- before (cephalic/reflex phase)
- during (gastric phase)
- after (intestinal phase)
How does the intestinal phase control gastric secretions?
contents are released into duodenum which stimulates reduction of gastric juice production
How are the rhythmic contractions of the stomach paced?
stimulus influences peristaltic waves because of the presence of autorhythmic cells
When does the stomach empty?
within 4 hours after a meal
The emptying of the stomach is largely dependent upon what?
ability to liquefy food and digestion in duodenum
What part of the duodenum secretes bicarbonate-rich mucus?
duodenal glands
What accessory organs also secrete into the duodenum?
gallbladder
pancreas
What stimulates the duodenum?
stretch and change in chemical environment
What is the role of the gallbladder?
storage site
What produces bile?
gallbladder
What are the characteristics of bile?
- yellow-green, alkaline solution
- contains bile salts, pigments, cholesterol, triglycerides, phospholipids, and electrolytes
- main pigment is bilirubin
What is the backbone of bile salts?
cholesterol
What are gallstones?
crystals formed from an imbalanced chemistry, which are then surrounded by cholesterol
What is the result of gallstones?
trapping of material which could result in Jaundice and impairment of digestion of fats
What is the role of the pancreas?
secretes pancreatic juice
What is found in pancreatic juice?
bicarbonate ions
digestive enzymes
What are released in an inactive form and become active in the duodenum?
proteases
The release of bile is stimulated by what?
bile salts
Cholecystokinin (CCK)
CCK is released by what cells in response to what?
released by intestinal cells in response to high fat content of chyme
CCK also stimulates the release of what type of juice?
pancreatic juice
Pancreatic juices are released from what type of cells?
enteroendocrine
How does sympathetic stimulation alter digestive activity?
inhibits digestive activities
How does parasympathetic stimulation alter digestive activities?
enhances secretion and motility
What makes up the abdominal (peritoneal) cavity?
- serous membrane
- peritoneal cavity (parietal and visceral)
- mesentery
What is peritonitis and what is it caused by?
inflammation of peritoneum
bacterial or fungal infection
What are the modifications of the small intestine that increases absorption?
- muscular layers force chyme to spiral through lumen, slowing its movement and increasing absorption
- villi increase surface area
Compare and contrast water-soluble and fat soluble vitamins
water-soluble are soluble in water and are excreted in excess
fat-soluble are soluble in fats and are stored
Where are electrolytes absorbed?
- most absorbed throughout small intestine
- iron and calcium absorbed in duodenum
Where is most of the water absorbed?
small intestine, 95%
Why can water move freely back and forth across the intestinal mucosa by osmosis?
moving solutes across makes water follow
What are common disorders of the digestive system?
constipation/diarrhea
appendicitis
What is Celiac’s disease?
an autoimmune disorder that destroys villi, making digestion and absorption difficult
What happens due to Celiac disease?
surface area decreases
nutrient deficiencies
What is Crohn’s disease?
inflammatory condition
immune system treats foods/bacteria/other beneficial substances as foreign
What causes Crohns?
cause not well-understood, but is due to abnormal reaction of immune system
What happens because of Crohns?
build up of white blood cells, inflammation, and ulcerations
How is Crohns treated?
removal of infected parts, which decreases surface area and decreases digestion and absorption
What is metabolism?
sum of all reactions taking place
What is anabolic?
growth
like steroids
What is catabolic?
breakdown
like fasting
What does your heart prefer?
fatty acids
Which type of lipoproteins matter more when considering heart disease, heart attack etc.?
LDL
What can the heart take up and lose for energy?
lactate
What is a simple carbohydrate?
glucose
What is a complex carbohydrate?
glycogen
What are carbohydrates used for?
energy
Carbohydrates are stored as what?
glycogen or fat
What is glycogenesis?
formation of glycogen
What is glycogenolysis?
liver
glycogen breakdown
What hormones are involved in metabolism?
insulin
glucagon
What does insulin do?
stimulates uptake (removal from blood) and use of glucose inside the cell
What does glucagon do?
breakdown into glucose to enter circulation
Where does each phase of metabolism take place?
Glycolysis - cytosol
Transition Reaction - between cytosol and mitochondria
Krebs - mitochondria
ETC - mitochondria
What are the major forms of lipids?
triglycerides
cholesterol
What are the characteristics of saturated fat?
saturated by hydrogen
linear carbon chain makes it solid at room temperature
What are the characteristics of unsaturated fat?
not saturated by hydrogen
makes kink in chain that allows it to be liquid at room temperature
What is cholesterol used for?
sex hormones
membranes
Lipogenesis vs. Lipolysis
formation vs. breakdown
What are proteins composed of?
amino acids
The metabolism of proteins makes what?
ammonia
ammonia is toxic
urea
Vitamins act as what in metabolism?
coenzymes
K and B vitamins are produced by what?
bacteria
What are the water-soluble vitamins?
B and C
What are the fat-soluble vitamins?
A, D, E, & K
Minerals act as what in metabolism?
cofactors
