1
Q
what is the function of the digestive system?
A
to process the breakdown and absorption of food and the removal of waste food products from the body
2
Q
order of the digestive system
A
eat food
buccal cavity
salivary glands
epiglottis
oesophagus
stomach
liver
gall bladder
pancreas
duodenum (small intestine)
ileum
large intestine
rectum
anus
3
Q
function of buccal cavity
A
where we put food - opening into the body and the beginning of the digestive tract
where food is chewed to break it down
use our jaw and teeth to grind food up so it is easier to digest
Mechanical digestion
4
Q
function of the salivary glands
A
produce and release saliva into the buccal cavity
helps to moisten food which makes it easier to swallow
contains amylase which is an enzyme that starts the chemical digestion of sugars
Chemical digestion
5
Q
function of the epiglottis
A
a flap of cartilage behind the root of the tongue which covers the opening of the windpipe when swallowing food
this prevents food particles and liquids from entering the larynx and trachea and getting into the lungs - prevents choking
6
Q
function of the oesophagus
A
a muscular tube that connects the buccal cavity to the stomach.
It is lined with muscles to push the bolus down to the stomach in a rhyming motion called peristalsis.
7
Q
function of the stomach
A
receives chewed food from the oesophagus
tiny glands in the stomach lining secrete gastric juice, which contains acids, mucus and enzymes
mechanical digestion - muscular walls churn the food
chemical digestion - acid and enzymes work together to break down carbs, proteins, fats into smaller molecules
this results in a ‘soup’ called chyme
8
Q
function of the liver
A
main function is to process the nutrients absorbed from the small intestine
Bile produced from the liver is stored in the gallbladder, before being secreted into the duodenum. Bile emulsifies fats and helps chemical digestion in the duodenum, jejunum and ileum.
9
Q
function of the gall bladder and bile duct
A
the small sac shaped organ beneath the liver, in which bile is stored after secretion by the liver and before the release into the small intestine.
the bile duct releases bile into the duodenum
10
Q
function of the pancreas and pancreatic duct
A
a large gland behind the stomach which secretes digestive enzymes into the duodenum to aid chemical digestion.
it secretes the hormone insulin and glucagon into the blood
11
Q
function of the duodenum and ileum (SI)
A
runs between the stomach and large intestine
made up of 4 sections
- duodenum
-jejunum
-ileum
-caecum
chyme then enters the duodenum and is mixed with bile and enzymes from the pancreas, so chemical digestion continues.
the ileum is covered in finger like projections called villi that increase the surface area of the small intestine to increase the rate of absorption of nutrients into the blood
12
Q
function of the large intestine
A
this is wider and shorter than the small intestine
typically divided into ceacum, colon and rectum
absorption of water and the formation of faeces happens here
13
Q
function of the rectum
A
faeces are stored in the rectum until they are passed out of the body through the anus
14
Q
function of the anus
A
the opening at the end of the digestive tract through which solid waste matter leaves the body
15
Q
what is mechanical digestion?
A
- when food is physically broken down to make it smaller.
- chewing action = teeth break down large pieces of food into smaller ones that can be swallowed.
- the stomach churns food to break it down
- in the small intestine, the bile emulsifies lipids which helps with the mechanical digestion of fats.
16
Q
what is chemical digestion?
A
- where nutrients are broken down by enzymes to smaller molecules that can be absorbed into the blood and used by cells.
- in the buccal cavity, food is dissolved with saliva, which contains an enzyme called amylase to break down carbs.
- the stomach mixes food with enzymes and hydrochloric acid while churning it. The hydrochloric acid helps to break down the food as well as killing the bacteria in the stomach to prevent illness.
17
Q
Action of digestive enzymes in stomach
A
- proteins broken down into amino acids by proteases, such as pepsin.
- HCL creates an acidic environment which generates pepsin
- digestive juices released.
18
Q
Action of digestive enzymes in small intestine
A
- proteins broken down by pepsin
- chyme that enters is acidic so it is neutralised by the bile as small intestine needs alkaline conditions for enzymes to work.
-fats broken down by lipase in fatty acids and glycerol for absorption. Bile also aids this by emulsifying fats. - starch broken down by amylase.
19
Q
how do enzymes work?
A
enzymes are folded into complex 3D shapes that allow smaller molecules to fit into them. The place where these molecules fit is called the active site. In the lock and key hypothesis, the shape of the active site matches the shape of its substrate molecules. This makes the enzyme highly specific.
- enzymes have a specific shape.
- large food molecules bind to the active site on the enzyme.
- the enzymes break chemical bonds of the food molecules thereby breaking them into smaller molecules that can be absorbed from the small intestine into the blood stream.
-enzymes work best in alkaline conditions and at 37 degrees (body temp)
20
Q
Digestive roles of pancreatic juice
A
-the pancreas produces digestive enzymes that are released into the small intestine in pancreatic juice
- the pancreatic juices that are released into the duodenum help the body to digest fats
- the pancreatic juices are released into a system of ducts that culminate in the main pancreatic duct
21
Q
Digestive role of bile
A
- bile is a digestive juice produced by the liver and stored in the gallbladder. It is released into the duodenum by the bile duct. Bile is needed for the process of emulsification. Emulsification is the breakdown of fats into fatty acids and glycerol. Emulsification needs to happen because insoluble fat molecules need to be broken down into fatty acids and glycerol so they can be absorbed into the blood stream.
Bile emulsifies fats so that lipase produced by the pancreas can break down fats.
22
Q
what are villi?
A
tiny finger-like projections that increase the surface area of the small intestine.
23
Q
3 adaptations of villi for absorption of nutrients
A
- wall is only one cell thick because it ensures that there is only a short distance for absorption to happen by diffusion and active transport
- network of blood capillaries because it transports nutrients, glucose and amino acids away from the small intestine into the blood
- internal structure called a lacteal which transports fatty acids and glycerol from the small intestine into the lymph.
24
Q
Absorption definition
A
- is the movement of nutrients, water and electrolytes from the lumen of the small intestine into the cell then into the blood
25
Assimilation definition
- is the movement of digested food molecules into the cells of the body where they are used.
e.g. glucose is used in respiration for energy
26
Role of the liver in assimilation
- excess glucose in the blood reaching the liver is converted into glycogen to be stored or broken down through respiration, producing energy
- where toxins, such as alcohol, are broken down
- distributes nutrients to cells when they are needed.
- involved in deamination - where part of an amino acid is removed to form urea, followed by the release of energy from the remainder of the amino acid.
27
Biological explanation of IBS
- where food moves through the digestive system either too quickly or too slowly.
- if food moves too quickly, it causes diarrhoea because not enough water is absorbed by the intestines.
- if food moves too slowly, it causes constipation because too much water is absorbed by the intestines and this makes the faeces hard
- it is also thought that problems with the absorption of bile during the digestive process may be a cause of IBS in some cases.
28
Symptoms of IBS x8
- Stomach pain and cramping
- Diarrhoea
- Constipation
- Bloating and swelling of the stomach
- Excessive wind
- Sudden need to go to the toilet
- Feeling that the bowels have not fully emptied after going to the toilet
- Mucus passing from the anus
29
Causes of IBS
- Exact cause is unknown
- Sensitivity of the gut to certain food
- Problems digesting foods
- Symptoms are often triggered by something that has been eaten or drunk or even stress
30
effects of IBS
- increased risk of other bowel disorders
- impact intimate life/relationships
-having to cancel plans
- can prevent people from leaving the house/attending events as need to leave often to use toilet - may feel embarrassed doing so
- may feel lonely because don't attend social events due to what others think
31
Treatment for IBS
CHANGES IN LIFESTYLE
- Low FODMAP diet
- Cut down on high fibre foods
- Avoid products containing a sweetener called sobitol
- Avoid foods that are hard to digest, such as cabbage, broccoli, beans and onions
- eat up to 1 tablespoon of linseeds a day
- administration of drugs that alleviate symptoms
32
evaluation of treatment for IBS
- It may be difficult for the individual to cut out/restrict certain foods - in doing this, they may struggle to get all the right nutrients and vitamins that they need, meaning they are at higher risk of getting vitamin deficiencies.
- medication is good as it is accessible, however some people may have religious or ethical reasons as to why they can't have the drug.
33
monitoring of IBS
Severity scoring system - used to monitor the severity of the disease and also to monitor the effectiveness of the treatments used
e.g is score lower once trigger foods have been restricted
- keeping a food diary to identify foods/drinks that cause irritation
34
care needs of individuals with IBS
- need advice and support with making changes to lifestyle and managing symptoms as there is no cure for IBS
35
Impact on diet and lifestyle - IBS
- Abdominal pain and discomfort from bloating may restrict sleep, leading to tiredness and emotional frustration
- The need to use the toilet may restrict trips out or socialising
- Excessive wind may be embarrassing and reduce confidence when socialising with others
- Can restrict diet and may make socialising difficult and embarrassing as the individual may not be able to eat or drink the same as friends.
- Coffee and fizzy drinks can cause irritation in the gut, so need to be avoided
- May need to avoid stressful situations which is not always easy
- Keep a food diary to identify foods that cause irritation or pain
- Take regular exercise - can relieve stress and increase feelings of wellbeing
36
Biological explanation of Coeliac disease
- an autoimmune condition which mistakes part of the body for a threat and attacks it.
- the immune system mistakes Gliadin, a substance found in gluten, as a threat to the body and attacks it.
- this causes damage to the villi.
- the antibodies cause the surface of the intestine to become inflamed and the villi are flattened, meaning the body’s ability to absorb nutrients is disrupted.
- villi normally help nutrients from food be absorbed through the small intestine walls into the bloodstream.
- coeliac disease is not a food allergy or a gluten intolerance.
- it is an autoimmune response where health substances are mistaken for harmful ones and the body produces antibodies against them
37
Symptoms of Coeliac Disease
- Indigestion
- Stomach pain
- Bloating
- Flactulence
- Diarrhoea
- Constipation
- Anaemia
- Loss of appetite
- Feeling tired all the time as a result of malnutrition
- Children not growing at the expected rate and adults experiencing unexpected weight loss.
38
Causes of coeliac disease
- Often runs in families - if someone has a close relative with the condition their chance of developing it is higher
- Research has shown it is strongly associated with a number of genetic mutations that affect a group of genes that are responsible for the development of the immune system. These mutations are very common so it is thought that environmental factors may trigger the condition in other people.
- There is evidence that introducing gluten into a baby’s diet before six months may increase their risk of developing the condition
- effect of gluten = damages lining of the intestine walls and is a reaction of the immune system
39
effects of coeliac disease
- can lead to osteoperosis and anemia due to malabsorption of nutrients
40
Impact of coeliac disease on diet and lifestyle - what to do and impact on individual
- remove gluten from the diet by excluding wheat products, otherwise villi will be damaged
- take additional vitamin and mineral supplements - may be a deficiency until villi regrow, due to impaired absorption
- read food labels very carefully when shopping as flour is often used as a thickening agent = food shop may become more expensive so impacts people's financial stability
- take care when eating out = look for gluten free products = may restrict how many places you can eat out at
- take care when eating at the homes of family and friends
- avoid using oil that has been used to fry gluten
41
Treatment for coeliac disease
- give up all foods containing gluten for life to avoid long term damage to health = this could be difficult as people often find gluten free stuff to not taste as nice/find good alternatives so they may miss out on vital nutrients if they start to avoid certain foods.
- vaccinations eg: flu jab as individuals with coeliac disease are more vulnerable to infection
- vitamin and mineral supplements can also help correct any dietary deficiencies
- not a proper cure
42
monitoring of coeliac disease
- endoscopy examines the duodenum so can see how damaged the villi are
- during diagnosis an endoscopy is carried out to take a biopsy of the small intestine to be examined
43
care needs of individuals with coeliac disease
- need advice about making changes to their diet and managing complications that may develop
44
biological explanation of gallstones
- small stones, usually made of cholesterol, that form in the gallbladder
- form if there are unusually high levels of cholesterol inside the gallbladder
-form if there are unusually high levels of the waste product bilirubin in the gallbladder
- these chemical imbalances cause tiny crystals to develop in the bile. They gradually grow, often over many years, into solid stones that can be as small as a grain of sand or as large as a pebble. Sometimes, only one stone will form, but often several develop at the same time.
45
symptoms of gallstones x8
- abdominal pain which can be sudden and severe
- excessive sweating
-feeling sick
-vomiting
-jaundice
-itchy skin
- diarrhoea
- loss of appetite
sometimes there are no symptoms
46
causes of gallstones
- formation of lumps of solid material in gallbladder caused by an imbalance in the chemical make-up of bile
- more common in someone who is overweight/obese or aged over 40
- more common if they have a condition that affects the flow of bile (e.g: cirrhosis of the liver)
- high cholesterol diet
- family history of gallstones
47
effects of gallstones
- can lead to acute inflammation of the gall bladder
- may make it difficult to carry out certain tasks if in pain
48
impact of gallstones on diet and lifestyle
- individuals can lead a normal life without their gallbladder
- after removal of the gallbladder, it is recommended that avoid fatty and spicy foods which can cause bloating and diarrhoea.
- recommended to eat a healthy and balanced diet based on the eatwell guide
49
treatment of gallstones x3
-removal of gallbladder
-lithotripsy
-medication
50
removal of gallbladder
- gets removed when it is the best solution
- removed through keyhole surgery. This is where several small cuts are made in the abdomen and smaller surgical equipment is used to access and remove the gallbladder. Keyhole surgery has a fast recovery period and the scars left are only small.
- bile is still produced by the liver after removal of the gallbladder, but it will continuously drip into the digestive system rather than being stored first.
- removal stops pain, blockages and inflammation as it will no longer be there
- surgery prevents further complications such as jaundice, as well as preventing the gallstones from coming back
- risk of infection, bleeding, bile leakage, injury to the bile duct, intestine, bowel and blood vessels.
-side effects can include an intolerance to fatty foods, nausea, vomiting, heartburn and yellow diarrhoea.
51
lithotripsy
- a nonsurgical alternative to manage gallstones
- uses high energy sound waves to produce shock waves. A tiny endoscope probe is used to deliver the shock waves that shatter the gallstones. The camera on the endoscope allows the surgeon to see the stones shattering.
- only a one day, non invasive procedure
- quicker recovery time than removal
- about 70-90% of people are found to be free of gallstones within 3 months of treatment
- not very effective on larger gallstones
- multiple sessions may be required to clear all stones
- passing of stones may cause pain
52
medication for gallstones
- needs to be taken for at least 2 years
- can be used to dissolve small stones
- not prescribed often as it isn't always effective
- gallstones can reform once treatment has stopped
53
monitoring of gallstones
- ultrasounds can be used to monitor gallstones
- performed using a handheld device which sends high frequency soundwaves into the body. Echoes are converted to electrical impulses that show as a picture on a screen.
- can create an image of the gallbladder to see if stones are still there after treatment
- also used to diagnose gallstones
- easy to use
-doesn't use radiation so is safe
- sound waves can be blocked by bones so images may not always be clear
54
care needs of an individual with gallstones
- advice and support with making changes to lifestyle and post-operative advice
55
evaluation of identifying triggers - IBS
+ can remove triggers from diet which helps to ease symptoms
+ easy to do
- long process to identify specific foods
- hard to identify specific foods in a meal
56
evaluation of a low fodmap diet - IBS
+ it's proven to ease symptoms of bloating and constipation
+ health benefits from healthy eating
- hard to make sudden dietary changes (highly restrictive)
- nutritional deficiency
57
evaluation of avoiding stress - IBS
+ helps ease symptoms
+ health benefits - decreased risk of CHD + HBP
- stress may not be a trigger for IBS so may not be effective
58
evaluation of eating regular meals - IBS
+ eating smaller meals more often helps to not overstimulate digestive system
+ eating better quality foods - health benefits
- severe loss of appetite
- fibre deficient
- may not be effective for everyone
59
evaluation of gluten free diet - coeliac disease
+ body doesn't produce auto-immune response as no gluten in system
+ eases symptoms
+ prevents damage to lining of intestines
- hard to switch to a GF diet
- GF food isn't available everywhere (e.g restaurants)
- more expensive
- requires uncontaminated preparation space which can be difficult if everyone else eats food containing gluten
60
evaluation of vaccinations - coeliac disease
+ protects against infection as coeliac disease may make it more difficult to recover from infection
+ antibodies against these infections will already be made
- ethical issues = people may not agree with vaccinations
- side effects from vaccines
61
evaluation of vitamins - coeliac disease
+ helps with nutritional deficiency from GF diet
+ stronger bones
+ help immune system fight infection
- additional cost
- severe deficiencies may require professional treatment
62
evaluation of removal of gallbladder - gallstones
+ stops pain
+ prevents further complications such as jaundice.
+ prevents reoccurrences
+ ends symptoms
+ safe procedure
+ cure for gallstones
- recovery time from surgery
- potential complications - infection, bleeding, bile leakage, injury to bile duct, blood vessels
- may become intolerant to fatty foods
- nausea
- yellow diarrhoea temporarily after removal
- heartburn
63
evaluation of lithotripsy - gallstones
+ only a day long procedure
+ non invasive procedure
+ quicker recovery time than removal
+ around 70-90% are found to be free of gallstones within 3 months of treatment
+ very low risk of bleeding
- aren't effective on larger gallstones
- multiple sessions may be required to clear the stones
- passing of stones may cause pain
- gallstones may reoccur
64
evaluation of medication - gallstones
+ can dissolve small gallstones
+ non invasive
+ individuals can continue with daily life
- needs to be take for at least 2 years
- gallstones can reoccur once treatment has stopped
- not very effective so not prescribed often
- doesn't help ease symptoms
65
evaluation of endoscopy - diagnosis of gallstones
+ allows direct visualisation of the bile ducts and gallstones
+ simple, low risk procedure
+ cost effective
- perforation of an organ
- excessive bleeding
- infection
- tear in the lining of duodenum, oesophagus or stomach
- breathing or heart problems due to sedative
66
evaluation of ultrasound - diagnosis of gallstones
+ easy to use
+ not too expensive
+ safe imaging method as it doesn't use radiation
+ gives clear image of soft tissue that doesn't show up on an x-ray
- struggles to form images very deep in the body
- sound waves can be blocked by bones
Unit 4 HSC
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Decks in class (8)
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