Digestive System Flashcards
What is the function of the digestive system?
To break chemically and mechanically down ingested food, absorb nutrients and excrete waste products
State the 6 steps of digestion and which organs are responsible for each
- Ingestion: mouth (oral cavity, tongue, teeth)
- Propulsion: pharynx/oesophagus/intestines
- Digestion: oral cavity/stomach/duodenum
- Absorption: jejunum/ileum/large intestine
- Assimilation
- Elimination: rectum/anus
What is ingestion?
The intake of food and fluids from the mouth into the alimentary tract
What is propulsion?
Movement of ingested food or fluid through the digestive tract
What is digestion?
The process of breaking down large, insoluble molecules into smaller, soluble molecules by chemical and mechanical means
What is chemical digestion? Give an example
- To break down food by changing the chemical structure, such as through acids or enzymes
- e.g. salivary amylase in the mouth or HCl in stomach
What is mechanical digestion? Give an example
- To physically break down food into smaller pieces, increasing their surface area, without changing the chemical structure, such as through chewing and muscular movements
- e.g. churning food in the stomach or mastication by the teeth
What is absorption
The process of moving digested food molecules/nutrients across the intestinal wall into the blood or lymph
What is assimilation?
The movement of digested food molecules from the bloodstream into cells
What is elimination?
The excretion of undigested food substances through the anus after processing in the intestines
Components of the digestive system
- Alimentary/digestive tract: mouth, pharynx, oesophagus, stomach, small intestine (duodenum, jejunum, ileum), large intestine (ascending, transverse, descending, sigmoid colon), rectum, anus
- Accessory components: salivary glands, pancreas, liver, gallbladder, appendix
What is W and what is its function?
Mouth
- To mechanically (teeth) and chemically (salivary amylase) break down food, acting as the point of entry and start of ingestion and digestion
What is a bolus?
Semi-solid mass of food
4 ways to maintain good oral health
- Regular dental check-ups to detect abnormalities early and have a greater chance of successful treatment
- Brush teeth and floss daily to remove pathogens and food particles
- Drink water containing fluoride to strengthen tooth enamel for protection
- Don’t smoke as it can degrade teeth and gums
What is B and what are its 4 functions?
Tongue
- Moves food bolus towards teeth during mastication so it can be mechanically digested
- Moves food bolus towards back of throat so it can be swallowed
- Speech
- Taste
Describe how the food bolus moves from the oral cavity to the oesophagus
- Tongue pushes food to back of oral cavity
- Epiglottis ensures food bolus moves down pharynx and not trachea
- Bolus goes down oesophagus
Structure and function of the uvula
- S = fleshy extension that hangs above the throat
- F = helps guide food bolus down the pharynx and prevent food going up the nose
Function of the teeth
To mechanically digest and break down food through tearing, grinding and cutting into small enough portions to swallow
What are A, B, C and D?
- A = enamel
- B = dentin
- C = gingiva (gum)
- D = pulp chamber (blood vessels and nerves)
- E = crown
- F = neck
- G = root
What is V and what is its structure and function?
Pharynx
- S = tube containing smooth muscle, lined with a mucous membrane. It has 3 parts: nasopharynx oropharynx, laryngopharynx
- F = to provide a passageway for food from the oral cavity to the oesophagus
What is U and what is its function?
Oesophagus
- To provide a passageway for the food bolus from the pharynx to the stomach via peristalsis (smooth muscle contractions and relaxations behind the bolus to push it down)
What 2 features of the oesophagus help it function?
- Mucosa and submucosa (mucous membrane): secrete mucus which provides lubrication and decreases friction as the food bolus moves down the oesophagus
- Smooth muscle: helps with peristalsis to move food bolus towards stomach
What is T and what is its structure and function?
Stomach
- S = a C-shaped muscular bag located in the LUQ
- F = to mechanically (churn food through muscle contractions) and chemically (HCl and enzymes e.g. pepsin) digest food
What is chyme?
Mixture of food, gastric juice and HCl created in the stomach
Describe the regions and sphincters of the stomach in the order that the food bolus moves through them
- Oesophageal sphincter opens to allow food bolus into the stomach
- Cardia: closest to oesophagus
- Fundus: most superior section, stores gases that are a byproduct of digestion
- Antrum: digests food mechanically and chemically (main body of stomach)
- Pylorus: end of stomach
- Pyloric sphincter: opens to allow food into duodenum
Structure and function of the small intestine
- S = has 3 sections (duodenum, jejunum, ileum), located in the abdominal cavity between the stomach and large intestine in the alimentary tract
- F = to absorb nutrients into the bloodstream e.g. carbohydrates/lipids/proteins
What is the mesentery?
Folded membrane that attaches the intestines to the abdominal cavity and holds them in place
Describe 4 features of the small intestine that assist with its function
- Thin walls: short diffusion pathway = increased rate of nutrient diffusion
- Rich blood supply to villi: maintain concentration gradient
- Contains villi (finger-like projections): large SA:V ratio = increased rate of absorption
- Mucous membrane secretes mucus: moist surface provides lubrication to reduce friction from movement of chyme
What is I and what are its structure and 3 functions?
Duodenum
- S = 1st part of small intestine, lined w villi and microvilli
- F = - final stage of digestion using bile from the gallbladder and enzymes from the pancreas (chemical)
- beginning of absorption of nutrients into bloodstream
- produces secretin in response to acidic chyme, stimulating the pancreas to release alkaline chemicals to maintain pH
What is J and what is its structure and function?
Jejunum
- S = middle section of small intestine, lined with villi and microvilli
- F = to absorb nutrients e.g. proteins, CHO, vitamins etc from digested food
What is K and what is its structure and function?
Ileum
- S = final section of small intestine, lined with villi and microvilli
- F = to absorb nutrients and most water from digested food
Structure and function of the large intestine
- S = located in the abdominal cavity between the small intestine and rectum, consists of caecum, ascending, transverse, descending and sigmoid colon
- F = to absorb EXCESS water (ileum absorbs most) and ions, to form semi-solid faeces from liquid chyme and transport it to the rectum for storage, to perform chemical digestion by gut microbes
What is P?
Caecum
What is Q?
Ascending colon
What is R?
Transverse colon
What is O?
Descending colon
What is N?
Sigmoid colon (terminal/end)
What is the ileocaecal valve?
Prevents backflow of chyme from the caecum (large intestine) to the ileum (small intestine)
Process of forming faeces
- Undigested food (chyme) enters colon from ileum
- Water, salts and vitamins are reabsorbed
- Undigested matter is dehydrated and compacted, forming semi-solid faeces
What are the components of faeces and what should healthy faeces look like?
- Water, fibre, microbes, epithelial cells from gut lining, mucus, fatty acids
- Should be a semi-solid sausage/snake shape
What is diarrhoea?
Complete flow/discharge of watery wastes from the colon, as a result of malabsorption of water from faeces, leading to dehydration
What is M and what is its structure and function?
Rectum
- S = short tube starting at the sigmoid colon and terminating at the anal canal, inferior to the intestines, contains stretch receptors which send a message to nervous system to stimulate voluntary contraction of anal sphincter to push out faeces
- F = to store and compact faeces prior to elimination
What is L and what is its structure and function?
Anus
- S = external opening to the digestive system, containing an internal sphincter (involuntary smooth muscle) and external sphincter (voluntary skeletal muscle)
- F = to provide a pathway for faeces out of the body
What is G and what are 3 of its functions?
Liver
- To produce and secrete bile (dark yellow/green substance that aids in the digestion of lipids) to the gallbladder
- To metabolise lipids, carbohydrates and proteins
- To remove toxins from the body
Structure and function of bile
- S = green/yellow liquid composed of water, mucus, salts, cholesterol and bilirubin (result of RBC breaking down)
- F = break down insoluble fatty acids into smaller droplets, excrete bilirubin through faeces
What is H and what is its function?
Gallbladder
- To store, concentrate and release bile into the duodenum via the common bile duct
Function of the salivary glands
To secrete saliva which:
- Lubricates food to make it easier to move through the digestive system
- Chemically digests food with salivary amylase (breaks down starch)
- Cleans the oral cavity
- Destroys ingested pathogens using lysozymes
What is D?
Sublingual gland
What is E?
Submandibular gland
What is F?
Parotid gland (below ears)
What is S and what is its structure and function?
Pancreas
- S = feather-shaped abdominal organ located posterior to the stomach
- F = to produce and release enzymes e.g. amylase, lipase, trypsin (breaks down protein) for chemical digestion into the duodenum via the pancreatic duct, as well as hormones e.g. insulin and glucagon for maintenance of blood sugar levels
Describe how the body responds to hyperglycaemia
- Stimulus: high BGL
- Receptor: detected by beta cells in pancreas
- Effector: beta cells release insulin, causing liver and muscle cells to store glucose as glycogen
- Response: decreased BGL back to WNL
Symptoms of hyperglycaemia and how to treat this (short term)
- Dry mouth, extreme thirst (hyper/polydipsia), blurred vision, headaches, urinary frequency
- Adjust diet, increase exercise, adjust or add insulin
Describe how the body responds to hypoglycaemia
- Stimulus: low BGL
- Receptor: detected by alpha cells in pancreas
- Effector: alpha cells release glucagon, causing liver and muscle cells to break down stored glycogen into glucose
- Response: increased BGL back to WNL
Symptoms of hypoglycaemia and how to treat this (short term)
- Drowsiness, hyperhidrosis (excessive sweating), light headedness, paleness, hunger
- Consume high GI carbs eg sugar, honey, jelly beans
What is X?
Appendix
How to maintain a healthy digestive system
- Balanced diet: soluble fibre e.g. nuts, beans, fruit, lowers LDL levels, BP and inflammation and insoluble fibre attracts water to stool, making it easier to pass
- Probiotics to prevent pathenogenic gut bacteria and help microbiological barrier
- Manage stress
- Limit smoking, alcohol and caffeine
- Regular exercise to help movement of food bolus and faeces
- Maintain hydration to avoid constipation
What is diabetes and what are the 3 types?
- Condition whereby the body cannot maintain healthy BGL
- Type 1, type 2, gestational (pregnancy)
Implications of untreated/poorly managed diabetes
Damage to nerves and blood vessels which can cause MI, stroke, kidney failure, retinopathy, etc
What is type 1 diabetes?
Autoimmune disease where beta cells of the pancreas are destroyed, reducing their ability to produce insulin which regulates high BGL > rely on regular insulin injections
What is type 2 diabetes?
Lifestyle/diet related condition where the body can’t produce sufficient insulin or is resistant to the insulin it produces
What is GDM?
- Gestational diabetes mellitus
- Occurs during pregnancy, caused by excess counter-insulin hormones produced by the placenta
What is GORD?
- Gastroesophageal reflux disease (aka heartburn/acid reflux)
- Condition in which the contents of the stomach flow back into the oesophagus due to improper functioning of the oesophageal sphincter, only classified as GORD if occurs more than twice a week
What is IBS?
Irritable bowel syndrome
- A condition in which signs and symptoms of GI distress are present but no lesions (damaged sites) are found
What is IBD and what are two types?
- Inflammatory bowel disease: inflammation of the intestines
- Crohn’s disease: inflammation of the ileum
- Ulcerative colitis: inflammation of the colon
SBO
Small bowel obstruction
TPN
Total parenteral nutrition (IV nutrients)
What is coeliac disease?
An autoimmune disease where gluten triggers the body to attack villi in the small intestine, causing villous atrophy and hence malabsorption of nutrients
An/o
Append/o
Anus
Appendix
Appendic/o
Cholecyst/o
Appendix
Gallbladder
Col/o
Colon/o
Colon
Or/o
Stomat/o
Mouth
Enter/o
Duoden/o
Intestines
Duodenum
Oesophag/o
Gastr/o
Oesphagus
Stomach
Hepat/o
Ile/o
Liver
Ileum
Jejun/o
Pancreat/o
Jejunum
Pancreas
Proct/o
Rect/o
Anus and rectum
Rectum
Sigmoid/o
Gloss/o
Sigmoid colon
Tongue
Lingu/o
Dent/o,i
Tongue
Teeth
Odont/o
Gingiv/o
Teeth
Gingiva (gums)
Palat/o
Pylor/o
Roof of the mouth
Pylorus (opening between the stomach and the duodenum)
Caec/o
Bil/i
Caecum
Bile
Cholangi/o
Glyc/o
Bile duct
Sugar
Phag/o
Gluc/o
Eat, swallow
Sweetness, sugar
Amyl/o
Choledoch/o
Starch
Common bile duct
Prote/o
Pept/o
Protein
Digestion
Sial/o
Herni/o
Saliva
Hernia
Chol/e
Glycos/o
Gall, bile
Sugar
Diverticul/o
Ferr/i,o
Diverticulum
Iron
Uvul/o
Cheil/o
Uvula
Lip
Phas/o
Antr/o
Speech
Antrum
Sider/o
Lip/o
Iron
Fat
Jaundice
Yellowish discolouration of the skin and other tissues due to excessive levels of bilirubin in the blood (dysfunction of liver)
Anastomosis
Creation of a surgical connection between two structures e.g. during a colectomy the two ends are sewn back together
Diverticulitis
Inflammation of a small pouch in the digestive tract
Polyphagia
Distension
Excessive hunger
Expansion (generally of abdominal region) due to pressure from within
Vomiting of blood
Haematemesis
Dyspepsia
Abnormal condition of painful/difficult digestion
Colostomy
Surgical creation of an opening by connecting the colon to an opening in the abdominal wall
