Examination 3 Flashcards
What are the six muscular sphincters in the digestive tract?
Upper esophageal sphincter
Lower esophageal sphincter
Pyloric valve
Ileocecal sphincter
Internal anal sphincter
External anal sphincter
Which of the sphincters in the digestive tract are controlled by the somatic nervous system?
Upper esophageal sphincter
External anal sphincter
Which of the sphincters in the digestive tract are controlled by the autonomic nervous system?
Lower esophageal sphincter
Pyloric valve
Ileocecal sphincter
Internal anal sphincter
What is the “second brain”
The enteric nervous system.
What is the somatic nervous system?
Bodily processes that are consciously and willingly controlled by us (chewing and swallowing food).
What are the five basic processes of the digestive system?
Motility
Secretion
Digestion
Absorption
Excretion
What is the autonomic nervous system?
Bodily processes that are not consciously and willingly controlled by us (food moving from the stomach to the small intestine).
Approximately how long is the GI tube?
28 feet
What is the luminal surface area range?
200-400 square metres
How long does digestion take? How much of this time is spent just in the stomach and small intestine?
Digestion takes between 30-80 hours. Of which 5-8 are spent in the stomach and small intestine
What causes diarrhea and vomiting?
When the digestive system senses noxious substances, it seeks to expel them
What is the gut microbiome
Bacteria, archaea and other small eukaryotes. They help protect against pathogens and can interact with the digestive system. It is individually unique from person to person
Function of the mouth in digestion
Start of digestion. Teeth break down food, tongue tastes and positions the food to swallow
Function of the pharynx in digestion
Passageway for food
Aids in swallowing food
Esophagus
Long muscular tube
Brings food from the pharynx to the stomach
Stomach
J-shaped, muscular organ
Secretes gastric juices (HCl and pepsin) and mixes it with food
Stores food
Beginning of protein digestion
Small intestine
Long, muscular tube
Mixes food with bile and enzymes from pancreas and intestines
Digests most nutrients
Absorbs most nutrients and water
Colon
Part of large intestine
Muscular tube
Absorbs water and some nutrients
Stores waste
Cecum
Part of large intestine
Blind pouch between small and large intestine
Rectum
Part of large intestine
Passageway for feces
Stretching of wall stimulates defecation
Anal canal
Part of large intestine
regulates defecation
Anus
Opening at the end of system
Expels feces
Salivary glands
3 pairs of glands
Secrete saliva to help moisten food
Amylase in saliva helps begin starch digestion
Liver
Secretes bile to emulsify fats
Helps to process and store certain nutrients
Gallbladder
Small sac
Stores bile
Releases bile into small intestine
Pancreas
Gland behind stomach
Secretes enzymes to digest major nutrients
Secretes buffers to neutralize HCL
Enzymes secreted into small intestine
Abdominal breathing
Breathing where the abdominal muscles are engaged to fill lungs to maximum capacity
Thoracic breathing
Breathing where the diaphragm and intercostal muscles are engaged to fill lungs. Not max capacity
Peristalsis
Contraction of muscular tube to move contents along it
One way movement
Used in esophagus, stomach and large intestine
Segmentation
Contraction along muscular tube to move or mix contents
Allows movement in both directions
Used by small intestine, stomach and large intestine
Sphincters and valves
Aids in motility and helps prevent backflow
What are four diseases that affect GI motility
GERD - Gastroesophageal reflux disease
Gastroparesis - affects Pyloric valve
SBBOS - Small bowel bacterial overgrowth syndrome - affects
Ileocecal valve
Chronic constipation
Lumen
Single-celled layer of tissue along the GI tract that separates the inside of the GI tract from the outside of the GI tract.
What glands secrete stuff into lumen? What is it they secrete?
Salivary glands - saliva and amylase
Gastric glands - Acid
Exocrine Pancreas - Pancreatic juice
Liver - Bile
What cells in the epithelium secrete stuff into lumen? What do they secrete?
Goblet cells - Mucus
Paneth cells - Defensins
Specialized epithelial cells - Specialized IgA
Should we drink 8 cups a day, or whenever thirsty?
Drinking when thirsty is better because your body is telling you you need water. It is accurate but trying to get about 15% more water would be the most ideal there.
How much blood plasma in the body?
about 2500mL
Where is most water absorbed?
Small intestine
Where is water lost?
Excreted in feces, in urine and as sweat and evaporative water
What are four diseases in secretion?
Cystic fibrosis
Inflammatory and secretory diarrhea
Anchlorhydria - Low acid
Xerostomia - dry mouth
Homeostatic hunger
Hunger driven by need
Hedonic Hunger
Hunger driven by pleasure
Which of the two types of hunger have followed us through evolution?
Both. Food gives us pleasure as well as filling nutrient needs. Nowadays we just have more hedonic hunger than we used to
What is the goal of food advertising?
To stimulate hunger and get people to eat. Stimulates hedonic hunger
Where do most Canadians fall under the nutrient adequacy scale?
Most are in adequacy or excess
What happens with the absorbed foods when we eat?
Food is processed within 48 hours. Supports growth, maintenance and repair. Polymers and complex macros must be converted into usable units
Where do amino acids come from?
Protein
Where do monosaccharides come from?
Carbohydrates
Where do fatty acids come from?
Fat and lipids
Where do vitamins and minerals come from
Vitamins and minerals do not need to be broken down. They are absorbed as they are
What is an essential nutrient?
Nutrients that cannot be made by the body. Iron and Vitamin A are some examples. Deficiency causes disease
Where do chemical and physical digestion start?
In the mouth
What happens when food is presented to you?
A part of the brain lights up and triggers the second brain to get ready for digestion
What are the five tastes in the tongue?
Sweet, salty, umami, bitter and sour
How are taste receptors for different tastes segregated on the tongue?
They are not.
What happens when a taste is processed?
Receptors on tongue and nasal cavity send signals to CNS to stimulate digestion (second brain)
What are taste receptors
Proteins in a cell. They put out neurotransmitters. These receptors exist throughout the body and help to identify where each nutrient is going
Where does sweet come from
sucrose
where does sour come from
Acids (HCl)
Where does salty come from
Salt
Where does bitter come from
Quinine
Where does umami come from
L-Theanine. A non-protein amino acid
What are the “two stomachs”
Upper (muscular) and lower (glandular)
Glandular stomach
There are channels within the stomach that secrete stuff. Protected by mucus layer
invagination structure protects it from damage
Muscular stomach
Churns and mixes contents of stomach
True or false: Alcohol and aspirin are good for healing the stomach
NO
Where does the bulk of digestion happen?
Small intestine
Duodenum
Shortest part of SI
Villus length and microvilli maximize surface area and therefore absorption
Jejunum
Area between duodenum and Ileum
Ileum
Longest part of SI
Low villus height, less SA
Role of Liver, Gallbladder and pancreas in digestion
Secrete stuff into duodenum to aid in digestion
Sphincter of Oddi
Control flow of stuff into duodenum
where flow of stuff from liver, gallbladder and pancreas converge
What triggers the gallbladder to release bile
Presence of fats on lumen in SI
Villi
Tower structure
Capillaries go through to supply blood and for absorption
Coated in epithelial cells
epithelial cells have microvilli
Absorption happens on top third
Where do most absorbed chemicals go?
Straight to liver
Where do absorbed fats go?
Lymphatic system for drainage
What is secreted into duodenum when chyme enters
Bicarbonate - neutralizes Stomach Acid
Digestive enzymes - From pancreas. Some are anchored to lumen
Bile acids - from liver and gallbladder
What digestive enzymes are anchored to lumen?
Disaccharidases and amino peptidases
For a chemical to be absorbed by the SI, it must be
Water soluble or made soluble
Where to polysaccharides go
Become single saccharides and go to liver
Where do fats go
Become fatty acids and go to lymph system via thoracic ducts
Where do vitamins and minerals go
Are not broken down and just are absorbed
Can absorbed chemicals go through cells?
Yes. paracellular absorption
With respect to whole body water homeostasis, which of the following is False?
a) it is critical for good health that you drink 8 or more cups of water each day, even if you
are not thirsty
b) the mouth, stomach and upper small intestine can secrete about 7 liters of water each day
c) the lower small intestine and colon can absorb about 9 liters of water each day
d) water loss in the feces may be as low as 100 ml each day
A
Most of human digestion and absorption takes place in the stomach and small intestine.
Which of the following statements about anatomy and physiology of these organs is False?
a) acid and pepsinogen are secreted into the stomach
b) bile, made by the liver and stored in the gall bladder, is secreted into the upper small
intestine
c) villi and microvilli greatly increase the surface area of the stomach epithelium, where most
nutrient absorption takes place
d) water soluble nutrients enter the hepatic portal blood to travel from the small intestine to
the liver
C
n considering the absorption of different types of dietary components in the GI tract, which
of the following is false?
a) alcohol is partially absorbed in the stomach
b) polysaccharides are digested to sugars and absorbed in the small intestine
c) amino acids are carried from the small intestine to the liver by the hepatic portal
circulation
d) most of the dietary fat goes directly to the liver from the small intestine in the hepatic
portal circulation
D
Good stress’, like winning prize money in the lottery, can result in adverse health outcomes
mainly because:
a) everyone gets nervous about the possibility of winning a large sum of money
b) winning money invariably makes your friends jealous
c) winning money dramatically elevates core body temperature
d) winning a large sum of money causes a pronounced alteration in psychological state,
increasing homeostatic load
D
Aging has been shown to be a condition of decreased physiological complexity by analyzing
variability profiles in which of the following physiologically-controlled processes?
a) blood calcium homeostasis
b) heart rate variability
c) blood glucose homeostasis
d) Trier Social Stress test
B
Which of the following is not a common approach to identifying genes that are associated
with longevity?
a) ‘knocking out’ or knocking in’ specific genes to determine their function relative to
progressive health using animal models
b) comparing the genetics and life outcomes of human identical twins
c) genotyping and comparing populations that live to 100+ years of age to populations that
typically die younger
d) genotyping a large population and then following the health outcomes and longevity of
each individual
B
Which of the following is not a common approach to identifying genes that are associated
with longevity?
a) ‘knocking out’ or knocking in’ specific genes to determine their function relative to
progressive health using animal models
b) comparing the genetics and life outcomes of human identical twins
c) genotyping and comparing populations that live to 100+ years of age to populations that
typically die younger
d) genotyping a large population and then following the health outcomes and longevity of
each individual
B
vidence that genetics can play a major role in the aging process comes from a wide variety
of experiments suggesting that the nuclear, mitochondrial, and microbiome DNA pools can all
have an impact on our ‘longevity program’. In the case of the mice engineered to contain a
specific mutation in the mitochondrial enzyme DNA polymerase gamma, which of the following
statements is false ?
a) the mutant mice exhibit signs of dramatically accelerated aging
b) the mutant mice end up with multiple mutations in their mitochondrial DNA
c) the abnormal mitochondria are primarily found in skin cells
d) the mutated form of the mitochondrial gene ultimately transcribes an enzyme that can
replicate DNA but cannot participate effectively in DNA repair
C
n considering the ‘Blue Zones’ of extreme longevity, which of the following generalities
were concluded from these populations?
a) these populations take advantage of the most advanced technologies in health care
b) your connection to a strong social network has a large effect on your longevity
c) a lifetime involvement in athletic sporting activities is required for extreme longevity
d) retirement at a young age, before your job wears you out, is key for longevity
B
What is an important input factor to health, disease and aging in human adults?
a) genetics
b) lifestyle and healthcare behaviours
c) environment
d) all of the above
D
What happens in the Large Intestine
Colonic epithelium absorbs water and leftover nutrients
Microbes absorb available nutrients (Prebiotics)
Microbes produce some vitamins
Microbes produce gases
New microbes try to get a foothold in system
Combustion reaction in cells
Fuel + Oxidant = CO2 + H2O + Heat
What are examples of primary fuel
Glucose, Amino acids, Monoglycerides and fatty acids
What are examples of stored fuel
Glycogen in skeletal muscles and liver
Proteins in skeletal muscle
Triglycerides in Adipose tissue
Can fuel be stored in extracellular space?
No
How much energy does an adult typically need in a day?
2000KCal
How much energy is stored in adipose tissue and triglycerides?
100,000KCal
What are the functional stores of fuel?
Fats and Protein. Fats aid in insulation and cushioning. Protein makes muscle mass
Absorptive fuel
3-6 hours after meal
Nutrients are in bloodstream from intestinal absorption
Insulin up
Excess stored
Post absorptive fuel
Between meals
Energy stores mobilized to supply fuel in plasma
Glucagon up
