Human Physiology - Digestion Flashcards
What is physical digestion?
Digestion through chewing (mastication) and churning in stomach
What is chemical digestion?
Digestion through enzymes, juices,
What controls digestion?
Hormones, phypothalanus, pepsinogen, trypepsinogen
What enzymes are used in digestion?
CCK, Gastrin, Enterogasterone, Secretin, Glucagon, Insulin,
What does CCK do?
Causes gall bladder to contract, and release bile salts
What are the 4 components of the digestive system?
Ingestion
Digestion
Absorbtion
Egestion
What are the layers of the alimentary canal?
Lumen Mucosa Submucosa Muscle layer Serosa
What does Enterogasterone do? Where does it come from?
Excreted from duodenum from high concentration of fats in large intestine, slows peristalsis for more time to digest lipids
Where are bacterial flora? What do they do?
Found in large intestine, ferment indigestible carbohydrates, releasing acids and gases. Also synthesize vitamins B and K
What is egestion?
undigestible cellulose fibres stores until pressure against colon causes bowl movement
What are hormones?
Chemical messenger that travels through the blood stream
What is exocrine?
releases hormones through ducts
What is endocrine?
releases hormones directly into blood stream
What is secretin?
hormone that regulates secretions by pancreas in digestion
What is gastrin?
hormone released from the smell or sight of food, releases gastric juice
What is Insulin?
hormone released by pancreas and causes liver to absorb glucose from blood and convert it into glycogen for storage, can reduce blood sugar levels
What is glucagon?
hormone released in the pancreas for the liver to convert stored glycogen into glucose to increase blood sugar
What is the structure of the small intestine?
Villi and microvilli, used to increase surface area
What is a lacteal?
lymphatic vessels of the small intestine that absorb digested fats
What are some adaptations of the villi?
tight junctions between cells ensure molecules will pass through villi, long structures increase surface area, epithelial cells have more mitochondria to ensure cells have enough ATP to run active transport, lots of pinocytes are present, different kinds of proteins on apical and basal sides to assist in diffusion
How are nutrients moved out of the villus?
simple diffusion, facilitated diffusion, active transport, exocytosis
How are monosaccarides absorbed?
sodium - potassium pump, requires low concentration of sodium in the epithelium
How are lipids absorbed?
monoglycerides and fatty acids through emulsification with bile salts are turned into miscelles, these bile salts carry miscelles into the epithelial cells. They are then converted into triglycerides and combined with cholesterol to become a chylomicron
How are amino acids transported into epithelial cells?
active transport into, facilitated diffusion into capillary
What happens to the things absorbed in the small intestine?
transported to the liver, which filters and protects our bodies from the harmful stuff we eat
What is dietary fibre?
Cellulose
What is a primary structure / polypeptide?
formed in dehydration synthesis, amino group from 1 amino acid bonds to carboxyl group of another amino acid (peptide)
What is a secondary structure?
formed from polypeptide when H bonds cause chain to coil or fold, caused by R group
What is a quaternary structure?
interaction of 2 or more polypeptides
What are the steps of protein digestion?
- Denaturation - mastication / change in pH
2. Deamination - remove amino acids
What is gastric juice?
Pepsinogen, HCl, mucin
What is pepsin?
Pepsinogen activated by HCl, breaks polypeptides into smaller pieces called peptones
What does the pancreas excrete into duodenum?
Trypsinogen, Chymotrypsinogen, carboxypeptidase, HCO3 -1, Mucous aminopeptidase
What activated trypepsinogen?
enterokinase
What do trpsin and chymotrypsin digest?
long chain polypeptides –> short chain polypeptides
What is secreted from the duodenum?
pepsin, tripepsin, chymotrypsin, enteropeptide, erepsin, dipeptidase, enterochymase
What is erepsin?
group of enzymes secreted from intestinal mucosal cells (dipeptidase, aminopeptidases, carboxypeptidase)
What does dipeptidase do?
digest dipeptides into amino acids
What does aminopeptidase and carboxypeptidase do?
take individual amino acids from each end of the polypeptide chain
what does trypsin do?
breaks down peptones into peptidases and dipeptidases
what does peptidase do?
breaks down peptides and dipeptides into amino acids
What is the structure of the liver?
lobed
What is a portal triad?
branch of bile duct, hepatic portal vein and hepatic artery
how does the liver go through detoxification?
hepatocytes absorb toxic substances and convert them into non-toxic ones
What can be made in the liver?
cholesterol
How does liver regulate lipids?
synthesize lipids or break them down
How does the liver recycle red blood cells?
breaks doen RBC’s and haemoglobin, bilirubin from haemoglobin can be sent to gall bladder to make bile
What causes jaundice?
build up of bilirubin in bloodstream
What does jaundice indicate?
problem in liver
What are 3 types of disease in the liver?
Fatty liver, alcoholic hepatitis, alcoholic cirrhosis
What are the 3 monosaccarides?
ribose, glucose, fructose
What are monosaccarides?
(CH2O)n n= 3 - 8
What are disaccharides?
two monosaccarides bonded through dehydration synthesis
What are the 3 disaccharides?
sucrose, lactose, maltose,
What are polysaccharides?
monosaccharides linked together in long chains
what are the 3 polysaccharides?
cellulose, starch, glycogen
How do you release energy from a polysaccharide / disaccharide?
must be hydrolyzed - opposite of dehydration synthesis, requires water and is catalyzed by enzymes
Where does hydrolysis occur?
mouth and duodenum
What is salivary / pancreatic amylase?
enzyme that digests starch into disaccharides
What are the 3 disaccharides?
maltase, sucrase, lactase
What is maltase?
breaks down maltose in the ileum into glucose
What is denatured in stomach?
amylase
What is a monomer?
a molecule that can be bonded to other identical molecules to form a polymer
What do parital cells do?
Release HCl in stomach
What do chief cells do?
Release pepsinogen from stomach
What are mucous cells?
Release mucous to protect stomach from pepsinogen and HCl
What are the 3 parts of the small intestine?
Duodenum, Jejunum, Ileum,
What does the gall bladder hold?
Bile (Bile salts + Bile Pigments)
