Unit 2: The continuation of life Chapter 22: Delivery of Materials to cells (NUTRIENTS)...
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Transcript of Unit 2: The continuation of life Chapter 22: Delivery of Materials to cells (NUTRIENTS)...
Unit 2: The continuation of life
Chapter 22:
Delivery of Materials to cells (NUTRIENTS)
21/04/23 Mrs Smith Ch22 The delivery of nutrients to cells
1
Higher Human Biology
21/04/23 Mrs Smith Ch22 The delivery of nutrients to cells
2
Learning Intentions
To understand how nutrients are delivered by the bloodstream to every living cell in the
body..
Success Criteria1. Explain how glucose and amino
acids, the end products of digestion of carbohydrates and proteins, are absorbed into the blood stream.
2. Identify the parts of a villus and explain how it is adapted to its function.
3. Describe the role of the lacteal in transport of absorbed lipid.
Preparation for nutrient absorptionPreparation for nutrient absorptionFood is moved along the alimentary canal from the mouth, to the small intestine by peristalsis.
View the Peristalsis animation: http://www.westga.edu/~lkral/peristalsis/
As this happens digestive enzymes breakdown…..
large insoluble food molecules
small soluble molecules21/04/23 3Mrs Smith Ch22 The delivery of
nutrients to cells
mouth
anus
stomach
Large intestineGall bladder
Salivary glandsSmall intestine
Oesophagus
Rectum
Pancreas
liver
appendix
SG Revision: Labelling exerciseSG Revision: Labelling exercise
21/04/23 4Mrs Smith Ch22 The delivery of nutrients to cells
Enzymes: Scholar Activity
21/04/23 Mrs Smith Ch22 The delivery of nutrients to cells
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http://courses.scholar.hw.ac.uk/vle/scholar/session.controller?action=viewContent&contentGUID=e6928e85-bb13-a0f0-102d-f1072a4fcd30
Answers Scholar Activity
21/04/23 Mrs Smith Ch22 The delivery of nutrients to cells
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http://courses.scholar.hw.ac.uk/vle/scholar/session.controller?action=viewContent&contentGUID=e6928e85-bb13-a0f0-102d-f1072a4fcd30
Digestive Enzymes: revisionDigestive Enzymes: revisionDigestive enzymes at various parts of the digestive system act on different types of food molecule…
Small Intestine21/04/23 7Mrs Smith Ch22 The delivery of
nutrients to cells
1. Small Intestine1. Small Intestine
21/04/23 8Mrs Smith Ch22 The delivery of nutrients to cells
1. Small Intestine1. Small IntestineThe small intestine is well suited to food absorption because:
3. Each villus has a lacteal & blood capillary network for efficient transport of absorbed substances
1. It is long 2. It has a folded inner lining covered in villi
…So has a large surface area for absorption
4. The lining of each villi is one cell thick – so nutrients can pass through easily 21/04/23
9
Epithelial cells, bearing microvilli, project into the lumen of the gut
Intestinal gland
between the villi; contains
enzyme secreting cells and hormone releasing cells
21/04/23 10Mrs Smith Ch22 The delivery of nutrients to cells
• Glucose and amino acids, the soluble end products of carbohydrate and protein digestion, are absorbed into the epithelial cells from where the pass directly into the blood capillaries.
• The products of lipid digestion also pass to epithelial cells but instead of blood capillaries enter the central lacteal.
21/04/23 Mrs Smith Ch22 The delivery of nutrients to cells
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2. Absorption of nutrients2. Absorption of nutrients
• Nutrients requiring no digestion by enzymes are also absorbed by the lining of the small intestine. These include calcium, iron and many vitamins.
• Remember Vit B12 can only be absorbed if intrinsic factor (a poly peptide made by the stomach) is present to stimulate endocytosis by the membrane of the epithelial cells.
21/04/23 Mrs Smith Ch22 The delivery of nutrients to cells
12
2. Absorption of nutrients2. Absorption of nutrients
2. Absorption of nutrients2. Absorption of nutrients
Glucose
amino acids
fatty acids and glycerol
phosphates
BLOOD
Carbohydrates
Proteins
Lipids
large insoluble food molecules small
soluble molecules
Absorbed into blood
Absorbed into lacteal
digestion
Nutrients that don’t need to be digested (e.g. calcium, iron & vitamins) by enzymes are also absorbed by the small intestine. 21/04/23 13Mrs Smith Ch22 The delivery of
nutrients to cells
21/04/23 Mrs Smith Ch22 The delivery of nutrients to cells
14
Learning Intentions
To understand how nutrients are delivered by the bloodstream to every living cell in the
body.
Success Criteria4. Carry out an experiment to
examine the effects of bile salts
i) as an emulsifier and
ii) on the activity of lipase
Bile saltsBile salts
Bile salts are….
Stored in the gall bladder.
Pass into the small intestine
via the bile duct
Produced in the liver
21/04/23 15Mrs Smith Ch22 The delivery of nutrients to cells
Bile salts help us break down fat
• Bile is necessary for efficient digestion of lipids. During a meal, bile is secreted from the gallbladder into the small intestine. In the small intestine, bile helps to break dietary fat into smaller particles, a process called emulsification. Emulsified fat can be more easily acted upon by digestive enzymes. Without bile, digestion and absorption of fat is incomplete.
21/04/23 Mrs Smith Ch22 The delivery of nutrients to cells
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Investigating the effect of bile salts Investigating the effect of bile salts as an emulsifieras an emulsifier
Lipids are, insoluble in water and less dense than water (so float).
A B A B A BOlive oil
Water Bile salts solution
Emulsification – oil
droplets in water
Olive oil
WaterBile salts act as an emulsifier so oil still emulsified
Shaken
Emulsifier = a substance that preserves emulsion.21/04/23
17Mrs Smith Ch22 The delivery of
nutrients to cells
Discussion
• In test tube A, when the layers are shaken vigorously, the become mixed forming an EMUSION of tiny oil droplets.
• This does not last long the oil droplets settle to the top into two distinct layers again.
21/04/23 Mrs Smith Ch22 The delivery of nutrients to cells
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• In test tube B, when the layers are shaken vigorously, they again form EMUSION.
• However in this case the emuslsuin does not separate into two separate layers.
Conclusion
• An EMULSIFYER is an agent which reserves an emulsion. From this experiment it can be concluded that bile salts act as an emulsifier.
21/04/23 Mrs Smith Ch22 The delivery of nutrients to cells
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Action of Bile SaltsAction of Bile SaltsBile salt molecule:
Tail• lipid soluble • hyrdophobic (water-hating)
Head• water soluble• hyrdophilic (water-loving)
When shaken, with a lipid, the bile salt molecule becomes attached to the lipid with the lipid soluble tails pointing in to the centre.
Droplet of lipid
Bile salt molecule acting as an emulsifier
The heads are negatively charged
so the lipid droplets repel each other and
don’t rejoin. This is emulsification. 21/04/23 20Mrs Smith Ch22 The delivery of
nutrients to cells
FYI: What are Gallstones• Gallstones form when bile hardens into a small
pebble-like substance that can grow as big as a golf ball due to high cholesterol, too much bilirubin, or inadequate bile salts.
21/04/23Mrs Smith Ch22 The delivery of
nutrients to cells21
In the event, when gallstones clog these ducts, it causes inflammation to the gallbladder wherein if it stays there for a longer period of time, it can result to a severe damage or infection to the gallbladdder, liver or pancreas.
LipaseLipaseA digestive enzyme made in the pancreasActive in the small intestine where it catalyses the breakdown of lipid
molecules by cleaving off the first and third fatty acid molecules.
21/04/23 22Mrs Smith Ch22 The delivery of nutrients to cells
LipaseLipaseSUBSTRATE END PRODUCTS
Lipid molecule (triglyceride)
+
monoglycerideFree fatty
acids
LIPASE
21/04/23 23Mrs Smith Ch22 The delivery of nutrients to cells
Investigating the effect of bile salts on Investigating the effect of bile salts on the action of lipase the action of lipase
A B C A B CShaken + alkali
added to make pH 7
then left for 30 mins in water
bath at 37˚C
Olive oil
Lipase
Water Bile salts
Bile salts
Universal indicator
pH 4 pH 5 pH 7
Acid conditions due to breakdown of lipids to fatty acids by lipase
No digestion from
bile salts alone
Lower pH shows bile salts aid digestion of
lipid to fatty acid21/04/23 24Mrs Smith Ch22 The delivery of
nutrients to cells
Investigating the effect of bile salts on the action of lipase
• Here the lipid substrate is being used in olive oil.
• After 30 minutes the contents of tubes A and B are found to show a drop in pH indicating the presence of acidic conditions.
• It is therefore concluded that lipase has promoted the breakdown of lipid to fatty acids in tubes A and B.
21/04/23 Mrs Smith Ch22 The delivery of nutrients to cells
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Significance of the control tube• Since no change in pH is found to occur in tube
C, it is concluded that lipase is required to catalase the digestion of lipid and that bile salts alone are unable to bring about the digestive reaction
21/04/23 Mrs Smith Ch22 The delivery of nutrients to cells
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Comparing tube A and B• A has undergone a greater drop in pH than B. It is
therefore concluded that more digestion of lipid to fatty acids occurs when bile salts are present.
Bile salt molecules maintain an emulsion of lipid droplets. This increases the relative surface area of the lipid exposed to the lipase enzyme, so increases the number of substrate molecules that the enzyme can act on, thus aiding digestion.
Droplet of lipid
Bile salt molecule acting as an emulsifier
Why do bile salts aid digestion by Why do bile salts aid digestion by lipase? lipase?
21/04/23 27Mrs Smith Ch22 The delivery of nutrients to cells
Following digestion, monoglycerides and fatty acids, the end products of lipid digestion, combine with bile salts to form tiny water-soluble particles called micelles.
Micelles move to the surface of the intestinal epithelium, which has microvilli.
Absorption of the end products of lipid digestion Absorption of the end products of lipid digestion
Fatty acids and monoglyceride molecules leave the micelles and diffuse through the cell membrane into the epithelium.
21/04/23 28
Video: Micelles
21/04/23 Mrs Smith Ch22 The delivery of nutrients to cells
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Absorption of the end products of digestionAbsorption of the end products of digestion
They are then coated with lipoprotein and move out of the cell by exocytosis.
Lipid molecule (triglyceride)
fatty acidsmonoglyceride
+
After passing through the epithelium of the microvilli, the monoglycerides & fatty acids pass into the cell’s endoplasmic reticulum to be built back into lipid molecules (triglycerides).
E.R.
Lipoprotein coat
Exocytosis
Absorbed by lacteal
They get absorbed by the lacteal and are transported via the lymphatic system to the blood.
21/04/2330Mrs Smith Ch22 The delivery of
nutrients to cells
Task: Torrance-TYK pg169 Qu 1-3
21/04/23 31Mrs Smith Ch22 The delivery of nutrients to cells
21/04/23 Mrs Smith Ch22 The delivery of nutrients to cells
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Learning Intentions
To understand how nutrients are delivered by the bloodstream to every living cell in the
body.
Success Criteria5. Explain why the liver needs a dual
blood supply
6. Analyse data on the composition of plasma of hepatic artery, hepatic vein and hepatic portal vein.
4. The Liver4. The Liver
Hepatic artery carries oxygenated blood to liver
Hepatic vein carries
deoxygenated blood from the liver to the
vena cava
Hepatic portal vein carries deoxygenated blood to the liver directly from the gut
21/04/23 33Mrs Smith Ch22 The delivery of nutrients to cells
Portal SystemPortal SystemThe portal system is circulation where blood in a
capillary bed (e.g. gut) passes through a vein (e.g. hepatic portal vein) and into a second capillary bed (e.g. liver) before returning the normal circulation system.
This prevents the end products of digestion entering directly into the circulation system. They are passed through the liver instead, which removes anything toxic by metabolism or excretion and converts nutrients into useable or stored forms .
21/04/23 34Mrs Smith Ch22 The delivery of nutrients to cells
Composition of plasmaComposition of plasma
In liver:• excess glucose stored as glycogen• excess amino acid converted to urea
Hepatic artery contains blood with all essential nutrients + normal urea concentration
Hepatic portal vein contains blood plasma with high concentrations of the end products of digestion + normal urea concentration
Hepatic vein contains normal blood plasma concentrations of glucose & amino acids+ high urea concentration
Try the scholar activity:http://courses.scholar.hw.ac.uk/vle/scholar/session.controller?action=viewContent&contentGUID=8f30977c-4cb9-fe59-4dfa-86bf98b62bdd
21/04/23
35Mrs Smith Ch22 The delivery of
nutrients to cells
Scholar Activity
21/04/23 Mrs Smith Ch22 The delivery of nutrients to cells
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Try the scholar activity:http://courses.scholar.hw.ac.uk/vle/scholar/session.controller?action=viewContent&contentGUID=ae01a001-7a3a-b119-c268-9aa0c7ae8160
Answers: Scholar Activity
21/04/23 Mrs Smith Ch22 The delivery of nutrients to cells
37
Try the scholar activity:http://courses.scholar.hw.ac.uk/vle/scholar/session.controller?action=viewContent&contentGUID=ae01a001-7a3a-b119-c268-9aa0c7ae8160
Image source: .biomed.brown.edu
5. Role of the Liver in Metabolism5. Role of the Liver in MetabolismA. Carbohydrate metabolismA. Carbohydrate metabolism
• Animals gain glucose by eating carbohydrates. The liver regulates the concentration of the glucose in the blood (blood sugar).
• After a carbohydrate rich meal, blood entering the liver by the hepatic portal vein contains a concentration of glucose in excess of the bodies immediate requirements.
• In response to the hormone insulin from the pancreas, an enzyme in the liver promotes the conversion glucose to glycogen
21/04/23 38Mrs Smith Ch22 The delivery of nutrients to cells
Image source: .biomed.brown.edu
5. Role of the Liver in Metabolism5. Role of the Liver in MetabolismA. Carbohydrate metabolismA. Carbohydrate metabolism
• Up to 100g of excess glucose is stored in the liver as glycogen. Any more excess glucose is stored as lipids in the body’s fat reserves.
• If glucose is needed the glycogen breaks down releasing the glucose into the bloodstream.
• When the blood’s sugar level is low, a different hormone called glucagon is secreted by the pancreas.
• This activates a different enzyme in the liver which promotes the conversion of glycogen to glucose.
• Glucose is then released into the blood stream for use by living cells.
Liver cells remove certain lipid molecules from blood and alter them to make other lipids e.g. cholesterol.• Cholesterol in cell
membranes needed to make steroid hormones are synthesised in liver
• Excess cholesterol is processed by the liver & excreted in bile
Lipoproteins - formed in the liver
5. Role of the Liver in Metabolism5. Role of the Liver in MetabolismB. LipidsB. Lipids
21/04/23 40Mrs Smith Ch22 The delivery of nutrients to cells
Image sources: www.nlm.nih.gov
Fat-soluble vitamins are
stored in liver cells
e.g. Vitamins A, D, E &
K21/04/23 41Mrs Smith Ch22 The delivery of nutrients to cells
Image sources: www.nlm.nih.gov 21/04/23 42Mrs Smith Ch22 The delivery of
nutrients to cells
Image sources: www.nlm.nih.gov 43
3 types of plasma proteins are made in the liver. The amino acids needed for this are absorbed from the bloodstream by liver cells.
Transaminase enzymes in liver cells can convert one amino acid to another. So even when amino acids aren’t obtained from food, many can be synthesised by the liver cells.
Albumins
Cause osmotic return of water
from tissue fluid in
capillary beds
Globulins
Cause transport of
lipids and fat-soluble
vitamins
Fibrinogen
Have an essential role in clotting of
blood .
5. Role of the Liver in Metabolism5. Role of the Liver in MetabolismC. ProteinsC. Proteins
21/04/23 44Mrs Smith Ch22 The delivery of nutrients to cells
6. Fate of absorbed materials6. Fate of absorbed materialsMaterial Use In Body Fate of Excess
Carbohydrate
Glucose used by cells to obtain energy (for aerobic respiration)
Stored as glycogen in liver and muscles as fat
in fatty tissues
LipidsUsed by cells as a source of energy
Converted back to lipid & stored in fatty (adipose) tissue
Proteins
Amino acids used for protein synthesis (e.g. to produce enzymes,
hormones,
antibodies)
NOT STORED some used as an energy source
by cells following deamination in liver (converted to urea)21/04/23 45Mrs Smith Ch22 The delivery of
nutrients to cells
Metal ions• Zinc• Iron• Copper• Magnesium
Enzyme activators
Some vitamins & minerals absorbed from food play a key role in enzyme reactions:
= Co-factors
Iron = the co-factor responsible for
activating the enzyme catalase.
Co-enzyme = a small non-protein co-factor composed of an organic substance (e.g. a vitamins).
Vitamin B = an essential component of
co-enzymes: acts as hydrogen carriers
during aerobic respiration
6. Fate of absorbed materials6. Fate of absorbed materialsD. Vitamins & mineralsD. Vitamins & minerals
21/04/23 46Mrs Smith Ch22 The delivery of nutrients to cells
1. What is the function of villi?
2. What is the name given to the central lymph vessel in a villus?
3. Which foodstuffs are transported by lacteals.
4. What substances are required for the proper absorption of vit B12.
5. What is the name of the process in which amino acids are broken down in the liver?
6. What is the toxic end-product of this process?
7. Where is bile stored?
8. What is the prime function of bile?
9. What vitamins can be stored in the liver?
21/04/23 Mrs Smith Ch22 The delivery of nutrients to cells
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1. To increase the surface area of the small intestine for the absorption of food.
2. Lacteal3. Fats.4. Intrinsic Factor5. Deamination6. Urea7. In the gall bladder8. Bile emulsifiers (breaks up) fats.9. A,B12 and D
21/04/23 Mrs Smith Ch22 The delivery of nutrients to cells
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Label the diagram best you can to describe the blood flow to the Liver
21/04/23 49
Liver – Morton sheet
21/04/23 50
Pulmonary Artery Pulmonary Vein
Vena cava
Hepatic Vein
Aorta
Hepatic Artery
Hepatic Portal Vein
Label A, B and C and organ X, try other bits if you can
21/04/23 51
Class Worksheet
21/04/23 52Mrs Smith Ch22 The delivery of nutrients to cells
Gall bladder
Hepatic Vein
Vena Cava
Hepatic Artery
Aorta
Hepatic Portal Vein
Essay Questions: 2005
Describe the functions of the liver under the following headings
1.Production of urea. (2)
2.Metabolism of carbohydrates. (5)
3.Breakdown of red blood cells. (3)
21/04/23 Mrs Smith Ch22 The delivery of nutrients to cells
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Task: Torrance-TYK pg172 Qu 1-4
21/04/23 54Mrs Smith Ch22 The delivery of nutrients to cells
Task: Torrance AYK pg173-4 Qu’s 1-4
21/04/23 55Mrs Smith Ch22 The delivery of nutrients to cells
21/04/23 Mrs Smith Ch22 The delivery of nutrients to cells
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Humour?