Nutrition, Digestion, Absorption Flashcards
Heterotrophs
Gain nutrients by eating other organisms
Autotrophs
Solar energy => photosynthesis
T/F: heterotrophs depend on organic synthesis of autotrophs
True
A calorie
Heat needed to raise the temp of 1 gram of water by 1 degree Celsius
1 Cal =
1000 calories , 1kcal
1 joule =
0.239 cal
Metabolic rate
Measure of overall energy that needs to be met by food
Three sources of energy for the body
Fats, carbs, proteins
Basal metabolic rate
Metabolic rate at rest / rate to perform body functions at rest
T/F: Physical activity does not increase basal metabolic rate
False
Describe the order of substance the body uses as an energy source.
- Fats - more energy/gram and compact for storage b/c little H2O2. Carbs- stored in liver and muscle as glycogen3. Protein- metabolized as a last resort
Undernourishment
Too little food intake- own cells are metabolized. Body functions impairedCarbs to fat to proteins
Overnourishment
Too much intake- increased body massCarbs to fat to protein reserves filled and fat turns into body fat
T/F: humans digest outside the body
True
The body cavity where food is processed
The gut
T/F: The digestive system is continuous with the outside world
True
Enzymes secreted that break down food are from (general)
Exocrine glands
Describe general process of protein digestion
Broken down into amino acids, function differently in different species. If it entered the gut directly the immune system would pwn it
8 essential amino acids for humans
TTMV PILLTryptophanThreonineValinePhenylalanineIsoleucineLeucineLysine
You are outside the body as long as you don’t cross the plasma membrane
True
Three main parts of digestive tract (general)
Mouth, gut (tubular), anus
Villi and microvilli increase what in the intestine? What happens As a result?
Increases surface area.Absorption is maximized
Layers of the gut, inside to out
LumenMucosaSubmucosaCirculatory layerLongitudinal layerEnteric nervous systemPeritonium
The lumen
Center/ cavity of the gut
Mucosa
Epithelium lining + connective tissue (blood vessels and glands)
Submucosa
Neural networkIncludes two muscle layers: Circular layer and longitudinal(takes part in stomach aches)
Enteric nerve system
Nerve nets of neurons of the gut
Petronium
Slimey layer that prevents organs from chafing
Hydrolytic enzymes are
Digestive enzymes
Paritoid gland is
The top salivary gland
Sublingual / submandibular gland
Bottom salivary gland
Salivary glands secrete
Mucus an amylase
Mucus is
Mucin (glycosylated proteins) and inorganic salts in H2O
Amylase is
Carbohydrase that turns starch into maltose
Bolus is
Ball of food that is covered in mucus/saliva that slides down the esophagus
How do salivary glands help swallow food
It covers the oral cavity and esophagus in mucus
Food touches epithelial cells as it gets processed through the body
False
Saliva solubizes dry food so it can go down without scratching the throat
True
Describe how saliva takes care of oral hygiene
Constantly flushes mouthContains lysozyme that lyses bacteria
What enzyme breaks down starch and what does it turn it in to?
Amylase and turns it into maltose
Is amylase present in large quantities in carnivores?
No
Stomach fluid is made of what
HCl
What is a zymogen
Inactive enzyme precursor
The exocrine part of the pancreas secretes
Bicarbonate into the small intestine to neutralize HCl
Protein is stored for energy
FLASE
Describe the make-up and properties of fat
Anhydrous - hydrophobic tail/hydrophilic headSaturated with C-H bonds (triglycerides; hydrocarbons)Reside in adipose tissue
Circular layer
In SubmucosaConstricts gut
Longitudinal muscle
In Submucosa Lengthens gut
Circular and longitudinal muscle layers take part in
Peristalsis
Two substances that activate pepsinogen
HClPepsin
Autocatalysis and what type of feedback? Give an example
A substance can cleave its own inactive state to produce more active enzymeEx: pepsinogen and pepsin
An Enteric nervous system
One that can act on its own (ex: digestion in a coma)
When looking at digestion you are looking at the _____
Peritonium
Mucous = Mucus =
cellsLiquid in salivary glands
Lysozyme and potency
Agent in saliva that kills bacteria, but only bacteria not strong enough to escape it
Stomachs main function
To STORE food
Which is faster in the stomach: ingestion or digestion?
Ingestion
Digestion mainly happens in the
Small intestine
The Jejunum is part of what organ and what does it do?
Small intestine and absorption
Ileum is part of of what organ and function?
Small intestine and absorption
The duodenum is part of what organ and what’s its function
Small intestine and digestion
The duodenum requires help from _____ organs. They are the ____ and _____
Accessory organs and pancreas and liver
What are the accessory organs and are they a part of the digestive system?
Pancreas and liver. No they are not
What does the liver do for the digestive system
Secretes bile to break down fats
A zymogenic cell contains lots of
Rough ERs
Where is the pepsinogen protein modified?
Zymogenic cell
The parietal cell has lots of
Mitochondria to create energy for anti-porters using ATP
Partially digested food
Chyme
Major enzyme produced by the stomach?
Pepsin
Describe the act of HCl activating pepsin from pepsinogen
The inactive pepsinogen has a masking sequence that falls off in low pH conditions (HCl) and reveals the active site
True/False: pepsin is a protease
True
What is secreted by stomach cells to prevent what from digesting the stomach?
Mucus prevents proteases and HCl from digesting the stomach
What develops when the stomach is directly exposed to HCl/pepsin
Stomach ulcers
Stomach ulcer is cause by what specific bacterium
Helicobacter pylori
What causes urease to convert urea to bicarbonate and ammonium?
Bacteria
Muscles of the stomach walls ____ and ____ to mix contents with stomach secretions
Contract and expand
What type of contractions push the chyme into the digestive organs?
Peristaltic conteactions
What is the opening to the small intestine called?
Pyloric sphincter
Properties of the small intestine
Long but small in diameterSurface area the size of a tennis court3 structural parts
What are the 3 parts of the small intestine
DuodenumJejunumIleum
Through what does the liver secrete bile?
Common bile duct into the duodenum
What organ stores bile until needed?
Gallbladder
What does the pancreas do for digestion?
Secretes digestive enzymes and bicarbonate
Bile is mainly made of what and acts as
Salts - emulsifiers
Another name for emulsifiers and what does it do?
Surfactants- cuts up fat into smaller chunks to increase surface area
What are the small chunks of fat called?
Micelles
T/F:Emulsifiers have a lipophilic and lipophobic end
True
Lipases break down fats into ______ and ____ so they are able to pass through the microvilli
Di/monoglycerides and fatty acids
Once inside the cell glycerides and fatty acids are re-synthesized into ______
Chylomicrons
Chylomicrons are
Water soluble “lipoprotiens”
What do chylomicrons enter the blood through?
Thoracic ducts
Chylomicrons also pass into which two tissues?
Lymph vessels and Submucosa
Bile acids are synthesized from what
Cholesterol
What percent of bile is recycled and where
90% in the liver
Process of recycling bile is called
Enterohepatic circulation
What percent of bile is lost and where?
10% in poop, the major elimination method of cholesterol
Bolus enters the stomach through the
The lower esophageal sphincter
Lipoproteins consist of
A core of fat and cholesterol covered in apoliproteins
What allows lipoproteins to be water soluble?
Apoliproteins
Lipoproteins are _____ in the circulatory system
0
Lipoproteins are classified according to ______ . The more fat the ______ they are.
Density, the more fat the less dense
Chylomicrons are the _____ form of lipoproteins
Largest
What carries fat from intestines to liver and adipose tissue?
Chylomicrons
Which lipoproteins carry new triglycerides from the liver to adipose tissue?
Very low density lipoproteins (VLDL)
What lipoproteins carry cholesterol from the liver to the cells of the body? Good or bad cholesterol?
Low density (LDL)
What lipoproteins collect cholesterol from cells and bring it to the liver? Good or bad?
High density (HDL)Good
High LDL to HDL ratio is a risk for what?
Atherosclerotic heart disease
Which part of the pancreas plays a part in digestion?
The exocrine portion
The exocrine part of the pancreas releases digestive enzymes as
Zymogen
What zymogen enzyme does the pancreas secrete
Trypsinogen
What activates trypsinogen and where?
Activated by enterokinase in the duodenum
What produces the enterokinase for enzyme activation?
The cell lining of the duodenum
Through what process can active trypsin perform to activate trypsinogen
Autocatalysis
The exocrine part of the pang read secretes what to neutralize stomach HCl?
Bicarbonate
T/F:!Only the smallest products of digestion can pass through the mucosa
True
Final digestion takes place where?
At the microvilli
Another name for where final digestion takes place?
Apical plasma membrane
What resides on microvilli membranes that cleave proteins?
Peptidases
What other “-ases” do the epithelial walls of the intestine produce? (to break down polysaccharides)
Maltase, lactase, and sucrase
What action pushes contents into the large intestine?
Peristalsis
What is another name of the large intestine
The colon
What does the colon absorb ad what is the product of that
Absorbs water and ions, makes feces out of indigestibles
Too much water absorption =Too little =
ConstipationDiarrhea
What bacteria lives in the colon and what does it do?
Escherichia coli- makes vitamin k and biotin
Why is it bad to take antibiotics
0
The logic in producing an inactive enzyme first is that
There is no damage to the tissue of the cell producing it
Blood vessels are connected to the _____ and ____ via _____
Parietal cell and lumen of the gastric pit via anti-porters
The parietal cell is connected to the lumen of the gastric pit via
Anti-porters and ion channels
What is the product of metabolism
CO2
In the parietal cell, CO2 reacts with what to make what and forms what as a by-product?
Water to make H2CO3 and forms bicarbonate as a by-product
The catalyst for the reaction between water and CO2 is
Carbonic anhydrase
Synthesized bicarbonate diffuses into the _____ while what ion comes in at the same time?
Bicarbonate diffuses into the blood stream while Cl- ions flow in
What ion constantly enters the parietal cell from the lumen of the gastric pit while which ion from the CO2 and water reaction goes in the opposite direction to the lumen?
K+ enters parietal from the lumen and H+ enters lumen from parietal
Once the H+ ion enters the lumen
It reacts with the Cl- ions to makeHCl the stomach acid
In the stomach, HCl is _____ and acts as a _____ to any bad substances
Acid-label and acts a defense
What does acid-label mean
Anything that can be acted on by acid (HCl)
What is the function of pepsin in the stomach?
To break down proteins at the tertiary structure
What type of cell secrets pepsinogen
Chief/zymogenic cell
Which cell secretes HCl?
The parietal cell
Where do gastric glands reside?
In the lining of the stomach
