Digestive System Flashcards
What is the digestive system and why is it important?
The food we eat is made up of large insoluble molecules that cannot be used in your body. The digestive system breaks down. These molecules chemically and mechanically into components that can’t be used and absorbed within the body and removes in digestible components.
An average adult consumes 1 kg of solid food and 2 L of water each day however this goes into providing energy and raw materials to maintain the structures we have and allows new tissues to generate an old ones to be repaired in adolescence. It provides a role materials for growth.
Why is appendicitis dangerous?
The gastrointestinal contains many bacteria and if the wall of the GI tractor is broken, e.g. the appendix rupture as a result of appendicitis there is danger infection known as peritonitis.
Where does the gastrointestinal truck start and end?
Mouth to anus and is 8 m long on average in addition to containing many different enzymes and bacteria to aid digestion
Name all the parts of the human digestive system
Human Digestive System (In Order)
1. Mouth – Chewing (mechanical digestion) & saliva (chemical digestion).
2. Pharynx – Passageway for food & air.
3. Oesophagus – Transports food to the stomach via peristalsis.
4. Stomach – Churns food; secretes acid & enzymes for digestion.
5. Small Intestine (Duodenum, Jejunum, Ileum) – Nutrient absorption.
6. Large Intestine (Cecum, Colon, Rectum) – Water absorption & waste formation.
7. Anus – Expels waste (feces).
Accessory Organs (Aid Digestion):
• Salivary Glands – Produce saliva with amylase.
• Liver – Produces bile for fat digestion.
• Gallbladder – Stores & releases bile.
• Pancreas – Secretes digestive enzymes & insulin.
Which is the only part of the GI track that has a bony skeleton?
The mouth has a bony skeleton as food moves around the mouth with the teeth bite down on the food and the taste buds are stimulated which intern stimulate this salivatory glands
Describe the functions of saliva
Moistens and softens food aiding turning it into bolus (food that is ready to be swallowed)
It lubricates the tongue to assess speech
It contains enzyme salivary amylase
Contains enzyme lysozyme which breaks down some kinds of bacteria to keep them mouth healthy
What is the role of the papillae
The tongues top surface is covered with roughened mucus membrane. The roughness is caused by numerous tiny elevations called papillae which increase the tongue surface area and contain taste buds
The average human has around 10,000 taste buds
What is the function of the epiglottis ?
The tongue passes food back to the pharynx which is controlled by the brain and medulla oblongata and Pons. To avoid food going down the trachea and into the lungs the epiglottis which is a flap of tissue covers the trachea preventing food from entering
Explain the location and structure of the oesophagus
The oesophagus is located immediately after the pharynx and is a 25CM muscular tube lined with a mucus membrane with its walls largely composed of muscular fibre
The upper part of the oesophagus is mainly skeletal voluntary muscle and the lower part comprise of involuntary muscle to enable an automatic wave of contraction known as peristalsis
What is a peristaltic wave?
A peristaltic wave is an automatic way of contraction which moves food progressively towards the stomach that is present in the lower section of the oesophagus
Each wave takes around 6 to 9/ seconds to reach the stomach swallowing can occur successfully even if the person is horizontal upside down due to it not being through gravity and instead the peristaltic wave
What is the cardiac sphincter role?
The cardiac sphincter is at the entrance of the stomach and remains open during swallowing allowing food to enter the stomach
Food takes 69 seconds to reach the stomach liquid arrives in one second
In reference to the stomach, what does the body the fundus and the pylorus refer to?
The fundus is at the top end of the stomach
The pylorus is the bottom end of the stomach
The body is the central part of the stomach
What role does the fundus and the body of the stomach act as
The thunders and the body of the stomach acts temporary reservoir for food secrete mucus, hydrochloric acid and pepsinogen because food can be eaten it more quickly than the intestines can absorb it. One of the functions of the stomach is to store the food.
What causes mechanical breakdown of food in the stomach?
Ripping peristaltic movements passed through the stomach every 15 to 20 seconds mechanically breaking down the food resulting in the production of chyme (a semi fluid mass of food and gastric juices)
The mechanical breakdown is caused by the peristaltic movements of three layers of smooth muscle all contracting in different orientations producing a cheering effect which can turn large meals into smooth pulp in a few hours
The outer contracts are short in the stomach
The middle (circular layer) is important near the pyloric sphincter as it controls chyme entering the duodenum
The inner layer contracts in a different direction
How many layers of muscles does the stomach have in comparison to the rest of the GI tract?
The stomach has three layers, the outermost (longitudinal) contracting and shortening in the stomach similar to the innermost ( oblique muscle layer)
The middle (circular muscle layer )has control over the pyloric sphincter regulating chyme entering the duodenum
Whereas the rest of the GI tract has two layers of smooth muscle circular and longitude muscles that are effective and creating peristaltic waves to move food through the system
What is the importance of gastric juice in the stomach?
Three different types of cells secrete into the stomach and they are products are known as gas juice
These products include mucus salts, water, hydrochloric acid, pepsinogen, and intrinsic factor
Intrinsic factors necessary for the absorption of vitamin B12 in the small intestine
Pepsinogen is the inactive form of pepsin an enzyme that is needed for protein digestion in the stomach and this optimum at low pH such as in the stomach, it is secreted an inactive form to avoid self digestion.
Along with pepsin hydrochloric acid and the contractions of the stomach Aidan, the breakdown of large lumps of food and catalyses the breakdown of large proteins creating chyme
Which part of the GI tract is responsible for mainly chemical digestion of proteins, carbohydrates, and fat into amino acids monosaccharides?
The small intestine is the main area for chemical digestion is about 6 m long in length and has one of the highest cell rem rate in the body. The epithelium is self renewing and replaces itself every six days on average.
Describe the structure of the small intestine and the relevant enzymes
There are three parts of small intestine
Duodenum – the weirdest and shortest part additionally the alkaline bowel from the gallbladder liver and enzymes from the pancreas flew into this unlike the jejunum which makes his own enzymes
Jejunum - 2.4 m long
Ileum – 3.6 m long
Which enzymes are involved in chemical digestion of food in the small intestine?
Trypsin a protease that breaks down peptides to amino acids
Amylase a carbohydrase that breaks down starch into simple sugar such as glucose
Lipase which breaks down fat molecules into fatty acids and glycerol
How long does it take for you to pass through the small intestine and why?
Food takes 3 to 5 hours to pass the small intestine because it is optimise to have a very large surface area about 200 m²
It is ideal for nutrient absorption as it is lined by villi which are fingerlike projections was greatly increase the surface area and aid nutrient absorption into the bloodstream
What is the size difference between the small and large intestine?
Small intestine is 6 m long and 2.5 cm thick whereas the large intestine is 1.3 m long but about 1.5 CM wide
Describe the structure and location of the large intestine
The large intestine begins past the ileum where a valve called the caecum stops anything from returning to a small intestine
The large intestine is composed of caecum colon rectum and anal cavity
And its main function is to absorb water from the indigestible food residue, secrete mucus to lubricate faeces, and eliminate the fess from the body
Waste typically remains in the colon for 16 to 20 hours while this process takes place
Describe the structure and location of the liver
Liver is located in the upper right hand portion of the abdominal cavity beneath the diaphragm on top of the stomach on the right kidney and intestines
It’s consist of two main lobes and two smaller ones old made of thousands of lobes
The lobes are connected to small ducts which connect with larger ones and ultimately form the hepatic duct
What is the function of the hepatic duct?
The hepatic duct is made of Loles within the liver which are connected to small ducks that connects with larger ducks to ultimately formed the duct
Its job is to transport bile produced by the liver cells to the gallbladder and to duodenum
What is bile function
Production of alkaline bile – removes waste products from liver, neutralises acids CHYME, emulsifies fats, physically breaks down large fat drops into smaller ones with the bigger surf area for enzyme action
What is the liver function?
Produces bile
Produces plasma proteins, including albumin
Produces cholesterol and proteins to curry fats through the body
Regulation of levels of amino acids in blood
Processing of haemoglobin
Conversion of poisonous ammonia to urea
Clearing blood of drugs
Regulate bloodline
Production of immune factors removing bacteria from bloodstream
Deliver synthesise dissolves in stores, amino acids, proteins and fats as well as important vitamins like vitamin B12 and vitamin a
What is the role of the hepatic artery?
It supplies liver with oxygenated blood carry nutrients needed for liver cells
What is the role of the hepatic portal vein?
Bring blood from the small intestine to be processed by the liver 75% of the total blood flow of the lower comes from the hepatic portal vein
What is the role of the hepatic vein?
The vein connects to the inferior of an cava and blood froze from the liver to the hepatic vein and eventually into the right atrium
What is the role of the hepatic duct?
It connects the liver to the gallbladder transporting concentrates of bile
What is bile and where is stored and created?
Bile is a liquid that contains water electrolytes, bile salts, cholesterol, phospholipids, and bilirubin
It is created in the liver where is transported via the hepatic duct to the gallbladder that sits on the right lobe of the liver where it is stored
Where is the cold bladder located?
On the right lobe of the liver connected by the hepatic duct
What are the functions of bile?
As bile is alkaline, it aids in neutralising stomach acid create a slightly alkaline environment in the duodenum which is key because pancreatic enzymes work most effectively at 7.5– 8 pH
House digest fats by breaking them down into smaller droplets for a bigger surface area for enzyme action
AIDS and waste product elimination through secretion into bile and elimination in faeces
If there are large amounts of bile salt secreted into the intestines every day how come only a small amount is lost from the body?
95% of delivered to the duodenum and absorbed back within the ileum via many thin tubes that make up the bile duct
How is The pyloric sphincter related to bile?
Key Link:
The pyloric sphincter controls when bile is needed, as bile is released in response to chyme (especially fatty food) entering the small intestine.
Describe the pancreas endocrine and exocrine functions
Pancreas: Endocrine & Exocrine Functions
- Endocrine Function (Hormone Production)
• The endocrine pancreas consists of Islets of Langerhans, which release hormones into the bloodstream to regulate blood sugar.
• Key Hormones:
• Insulin (β-cells): Lowers blood glucose by promoting uptake into cells.
• Glucagon (α-cells): Raises blood glucose by stimulating glycogen breakdown.
• Somatostatin (δ-cells): Inhibits insulin & glucagon release.
• Pancreatic Polypeptide (PP-cells): Regulates pancreatic secretions & appetite. - Exocrine Function (Digestive Enzyme Secretion)
• The exocrine pancreas consists of acinar cells, which produce digestive enzymes and release them into the duodenum via the pancreatic duct.
• Key Enzymes:
• Amylase: Breaks down carbohydrates.
• Lipase: Breaks down fats.
• Proteases (Trypsin & Chymotrypsin): Break down proteins.
• Bicarbonate (HCO₃⁻): Neutralizes stomach acid.
Summary:
• Endocrine → Hormones → Bloodstream (Glucose Regulation).
• Exocrine → Enzymes → Digestive Tract (Food Digestion).
The pancreas plays a dual role in metabolism & digestion!
Describe the endocrine pancreas
The endocrine pancreas is a group of cells called the islets of langerhans which consist of Alpha cells that produce glucagon a hormone that stimulates deliver to breakdown glycogen to glucose in increasing blood sugar level
And beta cells which produce insulin a hormone that stimulates conversion of glucose to glycogen and reduces blood sugar level
Describe energy usage of a person with low physical activity and the key indicators of energy use
Basal metabolic rate - energy used to fuel essential activities such as breathing organ on cellular function while at rest of sleep
65% of energy used
Thermogenesis – energy energy used to digest metabolism feed and maintain body temperature
10% of energy used
Physical activity - 25% of energy used
what is the target calorie intake for men and women and what are the proportions of each true source?
Men should have 2500 kcal and woman 2000 Kcal
Proportions should be
Fats less than 30%
Carbohydrate 45 to 65%
Protein 10 to 35%
Why is it important to get vitamins from the diet?
Vitamins cannot be made by the body so foods containing them need to be consumed
What are soluble vitamin B and C
Fat-soluble ADE.
Why is fire important in the diet?
Fibre cannot be digested so it provides bulk for the muscles in the digestive system to contract against
A hi-fi would die has been shown to prevent disease diseases such as diabetes weight gain and some cancers as well as improved digestive health
Describe metabolism, Anabolism and catabolism
Metabolism is a process which describes all chemical changes taking place in the body
Anabolism is where two small molecules are combined to form a larger and more complex organic molecule requiring the input of energy (ATP)
Catabolism is well. Larger molecules are broken down releasing energy as ATP.
What is ulceration? What can cause it within the digestive system?
Alteration refers to bleeding of the digestion track which is caused by an erosion of the protective mucosa which leads to digestive enzymes breaking down the wall of the digestive system
The self digestion can sometimes go all the way through the gut wall resulting severe infection and death. Most also are caused by the bacterium helicobacter pylori.
What is Gastro oesophagus reflux disease?
GORD is a reflux of the content of the stomach and the duodenum (gastric juice) into the oesophagus and this caused by a cardiac sphincter which is not working efficiently
In some cases of pressure of the stomach arises higher than the sphincter come with a star EG during pregnancy on a large meal bending over if particularly overweight
What is irritable bowel syndrome and what are the potential causes?
Irritable bowl syndrome is theorised to interfere with peristaltic muscular contractions in addition to having an increased sensitivity to various stimuli within the gut. Some patients link the start of their symptoms to major life changes which links IBS to psychological triggers
The symptoms include alternating constipation and diarrhoea, cramping abdominal pain, bloating, and constipation
Describe jaundice and it’s affects
Jaundice is a yellow appearance of skin or wet of the eyes due to an excess bilirubin pigment within the blood. Bel River is produced during the normal breakdown of red blood cells in the body and is excreted into the bile through actions of the liver and there is usually a sign of liver dysfunction however can be affecting the blood or spleen.
what is cirrhosis?
Cirrhosis is scarring of the liver that involves the formation of fibrous scar tissue in the destruction of normal organ structure and it uses you to long-standing injury e.g. excessive alcohol intake
There is no cure and only 30% of patience with this problem survive with five years after diagnosis and the outlook is worse if the cause of alcohol in the patient continues to drink
As the liver is responsible for removing poisonous substances from the blood if the liver is damaged these poisonous substances may pass to the brain where it can cause alteration in brain function causing confusion drowsiness and finally coma. This is called hepatic encephalopathy
What are protein pump inhibitors and what are they used to treat?
Protein pump inhibitors inhibit protein pump that pump hydrogen ions across cell membranes in the stomach lining that make hydrochloric acid
PPIs are used to treat stomach and duodenal ulcers (caused by H. pylori and NSAIDS
They are also used to prevent acid reflux so prevent or oesophagitis and symptoms of GORD
What medicine is used to treat gastrointestinal spasms and can be used to relax smooth muscle conditions such as IBS?
Antispasmodics
What are the three types of laxatives and how do they function?
Laxatives are used to relieve constipation
Bulk forming laxatives, provide fibre and relieve constipation by increasing focal mass which stimulates peristalsis
Osmotic laxatives increase the amount of water in the bowels and soft pieces so it’s easier to move
Stimulant laxative stimulate the gut water contract helping move faces along and out of the gut
How do you treat diarrhoea?
Anti-motility medicines can be used to treat diarrhoea which reduced to contractions in the gut. Me and the fetus will remain in there longer and more water can be reabsorbed.
Additionally, isotonic drinks and electrolytes can be used to rehydrate which will prevent the more serious side-effects of diarrhoea
