6.1 Digestion and Absorption
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6.1 Digestion and Absorption
6.1 Digestion and Absorption
6.1 Digestion and Absorption
6.1 Digestion and Absorption
6.1 Digestion and Absorption
6.1 Digestion and Absorption
6.1 Digestion and Absorption
6.1 Digestion and Absorption
6.1 Digestion and Absorption
6.1 Digestion and Absorption
6.1 Digestion and Absorption
Did you know?
Starter
6.1 Digestion and Absorption
The structure of the wall of the small intestine allows it to move, digest and absorb food.
Essential idea:
6.1 Digestion and Absorption
Vocabulary
Understandings
6.1 Digestion and Absorption
Syllabus Reference
| Statement | Guidance |
6.1.U1 | The contraction of circular and longitudinal muscle of the small intestine mixes the food with enzymes and moves it along the gut. | |
6.1.U2 | The pancreas secretes enzymes into the lumen of the small intestine. | |
6.1.U3 | Processes occurring in the small intestine that result in the digestion of starch and transport of the products of digestion to the liver. | |
6.1.U4 | Enzymes digest most macromolecules in food into monomers in the small intestine. | |
6.1.U5 | Villi increase the surface area of epithelium over which absorption is carried out. | |
6.1.U6 | Villi absorb monomers formed by digestion as well as mineral ions and vitamins. | |
6.1.U7 | Different methods of membrane transport are required to absorb different nutrients. | |
6.1.A1 | Use of dialysis tubing to model absorption of digested food in the intestine. | |
6.1. S1. | Production of an annotated diagram of the digestive system. | |
6.1. S2. | Identification of tissue layers in transverse sections of the small intestine viewed with a microscope or in a micrograph. | |
6.1 Digestion and Absorption
Expression Session
Starter
You have 15 minutes to create a something to express what you know about the 3 questions above. You may like to sing, rap, paint, draw, type, photograph, dance, write or talk.
Ingestion Digestion Absorption
Assimilation
Elimination
|
| undigested food residues are egested from the body as semi-solid faeces
food is taken into the body via the act of eating
digested food products are absorbed into the bloodstream and transported to cells
digested food products are converted into the fluid and solid parts of a cell / tissue
food is broken down both physically (e.g. mastication) and chemically (e.g. enzymatic hydrolysis) |
6.1 Digestion and Absorption
Label The Digestive System
6.1. S1 Production of an annotated diagram of the digestive system.
Highlight the Organs of the Alimentary Canal
6.1 Digestion and Absorption
Mouth and mechanical digestion
2 sets of muscles:
Rhythmic contraction and relaxation of these muscles results in a wave which pushes food along whilst mixing the food enzymes
6.1 Digestion and Absorption
What is peristalsis?
6.1.U1 The contraction of circular and longitudinal muscle of the small intestine mixes the food with enzymes and moves it along the gut.
6.1 Digestion and Absorption
What is peristalsis?
6.1.U1 The contraction of circular and longitudinal muscle of the small intestine mixes the food with enzymes and moves it along the gut.
6.1 Digestion and Absorption
What is peristalsis and segmentation?
6.1.U1 The contraction of circular and longitudinal muscle of the small intestine mixes the food with enzymes and moves it along the gut.
6.1 Digestion and Absorption
Stomach Acid
6.1 U3 Processes occurring in the small intestine that result in the digestion of starch and transport of the products of digestion to the liver.
6.1 Digestion and Absorption
Stomach Acid
6.1 U3 Processes occurring in the small intestine that result in the digestion of starch and transport of the products of digestion to the liver.
Food consists of:
–Carbohydrates
–Lipids
–Proteins
–Nucleic acids
–Minerals
–Vitamins
–Water
These are large, insoluble polymer molecules (aka macromolecules). They must be digested into monomers small enough to pass through the cell membrane of the cells lining the digestive tract so they can be absorbed into the bloodstream
Can be absorbed directly (because of their small size), so do not need to be “digested”
6.1 Digestion and Absorption
Why is digestion necessary?
Stomach Acid
6.1 Digestion and Absorption
Chemical Digestion
U4. Enzymes digest most macromolecules in food into monomers in the small intestine.
Bile
Enzymes
Reactions occur faster at higher temperatures, but the rate of denaturation of enzymes also increases at higher temperatures.
High temperatures break the bonds important for the tertiary structure of the enzyme.
This destroys the active sites and therefore makes the enzyme non-functional
6.1 Digestion and Absorption
Recap – What is the effect of temperature on enzymatic activity?
U4. Enzymes digest most macromolecules in food into monomers in the small intestine.
6.1 Digestion and Absorption
Examples of Enzymes
U4. Enzymes digest most macromolecules in food into monomers in the small intestine.
6.1 Digestion and Absorption
Examples of Enzymes
U4. Enzymes digest most macromolecules in food into monomers in the small intestine.
6.1 Digestion and Absorption
What happens when we digest starch?
U3. Processes occurring in the small intestine that result in the digestion of starch and transport of the products of digestion to the liver.
Cooking food prior to consumption initiates the breakdown of the polysaccharide, thus, aiding the action of amylase and the consequent digestibility of the carbohydrate component of the food.
6.1 Digestion and Absorption
What happens when we digest starch?
U3. Processes occurring in the small intestine that result in the digestion of starch and transport of the products of digestion to the liver.
6.1 Digestion and Absorption
What happens when we digest starch?
U3. Processes occurring in the small intestine that result in the digestion of starch and transport of the products of digestion to the liver.
6.1 Digestion and Absorption
What happens when we digest starch?
U3. Processes occurring in the small intestine that result in the digestion of starch and transport of the products of digestion to the liver.
6.1 Digestion and Absorption
What happens when we digest starch?
U3. Processes occurring in the small intestine that result in the digestion of starch and transport of the products of digestion to the liver.
Watch the videos, then complete the table:
6.1 Digestion and Absorption
Some videos which may assist you
Villi
Mucosa
Sub mucosa
Circular Muscles
Longitudinal Muscles
Serosa
6.1 Digestion and Absorption
6.1.U5 Villi increase the surface area of epithelium over which absorption is carried out.
6.1 Digestion and Absorption
Layers of the small intestine
6.1. S2 Identification of tissue layers in transverse sections of the small intestine viewed with a microscope or in a micrograph.
Serosa
E
Mu
S�C�L�S
Epithelial Layer (Villi)
Mucosa
Sub Mucosa
Circular Muscles
Longitudinal Muscles
Serosa
Mucosa
In the stomach the mucosa must withstand the low pH of stomach acids
In the small intestine it absorbs nutrients
In the large intestine it absorbs water
Submucosa
Circular Muscle
Longitudinal Muscle
Serosa
the outermost layer that covers the small intestine
6.1 Digestion and Absorption
Layers of the small intestine
6.1. S2 Identification of tissue layers in transverse sections of the small intestine viewed with a microscope or in a micrograph.
6.1 Digestion and Absorption
6.1.U5 Villi increase the surface area of epithelium over which absorption is carried out.
Single Layer Epithelial
Micro Villi
Membrane Protein
Rich Blood Supply
Lacteal
Muscle (L, C)
Serosa
A single villus
Lacteals absorb fat into the lymphatic system
Capillary network transports absorbed nutrients to rest of body
Single layer of epthelial cells
6.1 Digestion and Absorption
Villus structure
6.1. S2 Identification of tissue layers in transverse sections of the small intestine viewed with a microscope or in a micrograph.
6.1 Digestion and Absorption
6.1. S2 Identification of tissue layers in transverse sections of the small intestine viewed with a microscope or in a micrograph.
Microvilli - Greatly increase the surface area of the villus, allowing for a greater rate of absorption
Rich capillary networks - Maintains a concentration gradient for absorption by rapidly transporting absorbed products away
Single epithelial layer - Short diffusion distance between the intestinal lumen and capillary network
Lacteals - Absorb lipids from the intestine into the lymphatic system (later reabsorbed back into normal circulation) Triglycerides are emulsified by bile and hydrolyzed by the enzyme lipase, resulting in a mixture of fatty acids
Intestinal Glands – secrete enzymes
Membrane proteins / mitochondria - High amounts to enable active transport into cells (contents then passively diffuse into bloodstream)
Pinocytotic Vesicles – absorb ‘liquid’
6.1 Digestion and Absorption
Adaptations of the villi
6.1.U6 Villi absorb monomers formed by digestion as well as mineral ions and vitamins.
6.1 Digestion and Absorption
6.1.U5 Villi increase the surface area of epithelium over which absorption is carried out.
Make a short video or GIF to explain the features of a villus
6.1 Digestion and Absorption
6.1.U5 Villi increase the surface area of epithelium over which absorption is carried out.
6.1 Digestion and Absorption
6.1.U5 Villi increase the surface area of epithelium over which absorption is carried out.
6.1 Digestion and Absorption
6.1.U5 Villi increase the surface area of epithelium over which absorption is carried out.
Pretend you are on the phone to someone and you have 60 seconds to tell them how lipids are digested and absorbed
6.1 Digestion and Absorption
How are lipids digested? C
6.1.U6 Villi absorb monomers formed by digestion as well as mineral ions and vitamins.
6.1 Digestion and Absorption
Pinocytic Endocytosis
6.1.U6 Villi absorb monomers formed by digestion as well as mineral ions and vitamins.
6.1 Digestion and Absorption
6.1.U7 Different methods of membrane transport are required to absorb different nutrients.
6.1 Digestion and Absorption
6.1.U7 Different methods of membrane transport are required to absorb different nutrients.
a) State the missing source, optimum pH requirement, substrate and product of the human enzymes in the table below (2)
b) Explain the need for enzymes in digestion.(2)
c) Draw a labelled diagram to show the interconnections between the gall bladder, pancreas and small intestine.(3)
6.1 Digestion and Absorption
Past Paper Questions
d) Explain how the structure of a villus in the small intestine is related to its function (7)
(b) rate of digestion at body temperature would be too slow / enzymes increase the rate of digestion;
enzymes break large molecules down into small/soluble molecules;
for absorption/diffusion into blood; 2 max
(c) labelled sac-shaped gall bladder with a duct;
tubule/(bile) duct shown connecting gall bladder directly to small intestine/duodenum / tubule/(bile) duct merging with the pancreatic duct before entering small intestine; Alternative answers areaccepted because of variations in human anatomy.
pancreas drawn with pancreatic duct connected to small intestine and pancreas labelled; 3 max
A duct is preferred to a line, but since this is a diagram, both are acceptable.
6.1 Digestion and Absorption
To achieve [1] answer must name the structure and relate it to its function.
the villus has a large surface area to volume ratio;
microvilli increase surface area for absorption;
thin surface (epithelial) layer so products of digestion can pass easily through;
channel proteins located in plasma membrane used for facilitated diffusion;
network of capillaries inside each villus (so only short distance) for movement
of absorbed products;
capillaries transport absorbed nutrients/sugars and amino acids away from
small intestine;
blood flow in capillaries maintains concentration gradient;
central lymph vessel/lacteal to transport absorbed fats/fatty acids away from
small intestine;
large number of mitochondria provide ATP needed for active transport;
protein pumps in membrane (of microvilli) carry out active transport;
pinocytosis occurs at surface (epithelial) layer;
Accept any of the points above shown in a drawing. 7 max
6.1 Digestion and Absorption
Explain how the structure of a villus in the small intestine is related to its function (7)
Plenary Practise
6.1 Digestion and Absorption
Modelling Digestion
6.1 A1. Use of dialysis tubing to model absorption of digested food in the intestine.
6.1 Digestion and Absorption
Using visking tubing to model digestion:
6.1 A1. Use of dialysis tubing to model absorption of digested food in the intestine.
6.1 Digestion and Absorption
Open ended assessment task
Assessment
6.1 Digestion and Absorption
Quiz and Kahoot
Checkpoint