Digestion Flashcards
What are
proteins
Lipids
Carbohydrates
broken down into
Proteins - Broken down into amino acids
Carbohydrates - Broken down into monosaccharides
Lipids - Broken down into fatty acids and monoglycerides
Where does the absorption of nutrience happen
The ileum of the small intestine : Final section of the small intestine where nutrience are absorbed into the blood stream.
Enzymes are secreted by glands in its walls
Inner walls are folded into villi giving it a large surface area
What are the adaptations of the small intestine
- Internal walls are folded into projections called villi (1mm in length) giving it a large surface area
- Villi have thin epithelium (one cell thick) so it has a short diffusion distance
- Villi have lots of capillaries which help maintain the concentration gradient by constantly transporting absorbed nutrience away
- Villi contain muscles that move that help them to mis the contents of the ileum so villi always have new material next to them to absorb nutrience
What are the adaptations of the epithelial cells (ileum)
- Microvilli (folded membrane) which increases the surface area for diffusion further
- Many mitochondria to provide energy for active transport
- Channel and carrier proteins for active transport
- Membrane bound enzymes
How are carbohydrates broken down
Starch - (amylase) - Maltose - (maltase) - a glucose (2)
sucrose (sucrase) - Glucose and Fructose
lactose (lactase) - glucose and galactose
The glycosidic bonds are broken
How are carbohydrates absorbed
- Glucose and galactose are actively transported using sodium ions through co-transporter proteins
- Fructose is absorbed by facilitated diffusion through different transport proteins
What are the functions of the:
Mouth
Salivary glands
Oesophagus
Liver
Gall bladder
. Mouth- Hydrolyses amylase, physical and chemical breakdown, breaks down food for easy ingestion
. Salivary glands - secretes amylase
. Oesophagus - carrier food from the mouth to the stomach
. Liver - processes nutrience absorbed in the intestine, secretes bile
. Gall bladder - stores and concentrates bile
What are the functions of :
- stomach
- Pancreas
- Large intestine
- Small intestine
- rectum
- Anus
. Stomach - Hydrochloric acid kills pathogens, muscular sac that sores and digests food. Walls and glands produce digestive enzymes, Physical and chemical breakdown
. Pancreas - Amylase, protease, lipase and large gland producing pancreatic juice containing hydrolytic enzymes
. Large intestine - Absorbs water, chemical breakdown and absorption, bile, amylase, protease and lipase
. Small intestine - Absorbs soluble food molecules, chemical breakdown and absorption, bile, amylase, protease and lipase.
. rectum - Stores faeces
. Anus - egests faeces
where are carbohydrates broken down and how
salivary glands - produces the enzyme amylase in saliva. It breaks glycosidic bonds in starch to form maltose
pancreas - pancreatic amylase released into the small intestine. Breaks glycosidic bonds to hydrolyse starch to for maltose
Small intestine - hydrolyses glycosidic bonds to break down disaccharides into monosaccharides e.g. sucrase breaks down sucrose into glucose and fructose
What are the components of the small intestine
start - Duodenum
Middle - jejunum
End - ileum
How are proteins digested
Digested by peptidases or protease by hydrolysing the peptide bonds
Where are proteins digested and how
- Stomach - Hydrochloric acid denatures the proteins unfolding their 3D structure revealing the polypeptide chain. Enzymatic digestion by pepsin forms shorter polypeptide chains
- Small intestine - Trypsin, Chymotrypsin and protease continue digestion forming tripeptides, dipeptides and amino acids. In enterocytes tripeptides and dipeptides are further broken down into amino acids and are absorbed into the blood
- Pancreas- Fluid secreted travels to the small intestine and helps to neutralize the acidic mixture and increase the pH pancreatic juice contains endopeptidases and exopeptidases
What are the different types of peptidases and what do they do
- Endopeptidase - Hydrolyse peptide bonds within a large protein (polypeptide) to create smaller polypeptide chains
- Exopeptidase - Hydrolyse terminal peptide bonds (between amino acids and on the ends of a polypeptide chain) to remove individual amino acids and create smaller polypeptide chains
- Dipeptidase - Type of exopeptidase located on the membrane of epithelial cells lining the small intestine
Work specifically on dipeptides to hydrolyse the peptide bond holding them together creating to single amino acids that can be transported into the epithelial cells via membranes
How are proteins absorbed
Amino acids are absorbed a similar way to glucose and galactose through active co-transport with sodium ions
The sodium ions are actively transported out of the ileum cells so they diffuse back down their concentration gradient with amino aicds
What are membrane bound disaccharides
Membrane bound disaccharides are enzymes that are attached to the membrane of epithelium cells lining the ileum
They help to break down disaccharides into monosaccharides by the hydrolysis of glycosidic bonds
what enzyme is associated with the digestion of lipids
Lipase is an enzyme that hydrolyse the ester bonds in triglycerides to form fatty acids and monoglycerides
Where are lipids made and where do they act
Lipids are made in the pancreas and secreted into the small intestine
Where are bile salts produced and what do they do
Bile salts are produced by the liver and is stored in the gall bladder which releases them into the small intestine
They break large fat globules by emulsifying them into small droplets
Speeds up the action of lipase by increasing the surface area of lipids that can be exposed to the enzyme Lipase
Involved in the production of micelles
How are lipids absorbed
1- Micelles hit epithelial and breakdown allowing monoglycerides and fatty acids to diffuse across membranes because they are lipid-soluble
2- Monoglycerides and fatty acids and transported to the endoplasmic reticulum where they recombine to form triglycerides again
3- Inside the Golgi they bind with cholesterol and proteins and are packaged to form Chylomicrons
4- Chylomicrons travel in a vesicle to the cell membrane and are exocytosed from the epithelium cell
5- Chylomicrons enter the lymphatic capillaries called lacteals which transport them away from the small intestine to adipose, cardiac and skeletal muscles tissues where triglycerides can be hydrolysed and fatty acids used by the tissues
What are micelles
When lipids have been broken down by lipase the monoglycerides and fatty acids stay attached to bile salt and form smaller structures called micelles (4-7nm).
Helps with the absorptions of fatty acids and monoglycerides
What are sucrase and lactase an example of
Membrane bound disaccharidases
What are lipids broken down by
They are broken down by Lipase and the action of Bile salts
How do peptidases help in digestion of proteins
Not including functions
They create more ends therefore a larger surface area for absorption
What enzymes break down carbohydrates
Amylase
membrane bound disaccharidases
