Alimentary system physiology Flashcards by Mathew Campbell

Four main functions of the alimentary system?

Digestion
Secretion
Absorption
Motility

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Two types of digestion occurring in alimentary system?

Chemical

Mechanical

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Three pairs of salivary glands?

Parotid
Submandibular
Sublingual

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Where most absorption occurs in the alimentary canal?

The small intestine

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The three parts of the small intestine?

Duodenum
Jejunum
Ileum

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Problem caused by consumption of food with too much osmolarity?

Dumping syndrome

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Functions of saliva?

Lubrication

Dilution of foodstuffs

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First part of alimentary canal where digestion occurs?

The mouth

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Function of the oesophagus?

Conduit between oropharynx and stomach

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Functions of the stomach?

Storage of food
Digestion of proteins
Reduction of solid foodstuffs to chyme 
Production of intrinsic factor
Sterilisation of ingested food

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Enzymes which digest protein?

Pepsinogens

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Cells which produce pepsinogen?

Chief cells

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Organ which secretes majority of digestive enzymes in alimentary canal?

Pancreas

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Functions of the liver in the alimentary canal?

Filters blood coming from alimentary canal before it re-enters circulatory system
Secretes bile salts to aid with digestion and absorption of lipids

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Functions of the gallbladder?

Stores and concentrates bile

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Functions of small intestine?

Absorption of majority of nutrients

Final site of digestion of foodstuffs

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Functions of the colon?

Absorption of water, salts and some vitamins
Compaction and storage of feces
Site of bacterial fermentation

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Four common layers of the alimentary canal?

Mucosa
Submucosa
Muscularis externa
Serosa/adventitia

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Subdivisions of mucosal layer of alimentary canal?

Epithelium
Lamina propria
Muscularis mucosae

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Outer layer of gut tube within peritoneal cavity?

Serosa

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Outer layer of gut tube external to peritoneal cavity?

Adventitia

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Two layers of muscle in muscularis external?

Circular layer

Longitudinal layer

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Part of alimentary canal with third layer in muscularis externa?

The stomach

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Third layer of muscle tissue in muscularis externa of the stomach?

Oblique layer

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Two parts of alimentary canal with submucosal glands?

Oesophagus | Duodenum

Two layers of gut wall that submucosal plexus exists between?

Submucosa | Muscularis externa

Two layers of gut wall that myenteric plexus exists between?

Circular layer of muscularis externa | Longitudinal layer of muscularis externa

Layer of gut tube providing motility function of alimentary canal and their innervation?

Muscularis externa innervated by myenteric plexus

Nerve plexuses forming enteric nervous system?

Submucosal plexus and myenteric plexus

Epithelium present in mouth, oesophagus and anal canal?

Stratified squamous epithelium

Epithelium present in stomach, small intestine and large intestine?

Simple columnar epithelium

Functions of epithelial part of mucosa?

Absorption of nutrients Barrier between gut lumen and the body Synthesis and secretion of enzymes, hormones and mucus

Function of stratified squamous epithelium in mouth, oesophagus and anal canal?

Protection from friction and abrasion

Layer of gut tube containing blood and lymphatic vessels?

Submucosa

Inner layer of muscularis externa?

Circular

Outer layer of muscularis externa?

Longitudinal

Two forms of motility present in the alimentary canal?

Peristalsis | Segmentation

Form of nervous control mainly governing the alimentary canal?

Autonomic

Parasympathetic innervation of alimentary canal?

Vagus nerve

Sympathetic innervation of alimentary canal?

Splanchnic nerve

Function in alimentary canal not controlled by the vagus nerve?

Salivary secretion

Nerves controlling salivary secretion?

Facial nerve | Glossopharyngeal nerve

Effect of parasympathetic input on gut activity?

Increases gut motility | Increases rate of secretions

Effect of sympathetic input on gut activity?

Decreases gut motility | Decreases rate of secretions

Artery mainly supplying the foregut?

Celiac trunk

Artery mainly supplying the midgut?

Superior mesenteric artery

Artery mainly supplying the hindgut?

Inferior mesenteric artery

Structure which all blood from the gut drains through before eventually returning to the heart?

The liver

Reason that the liver and gut are in series?

The liver filters all the blood coming from the gut to purify it before it is returned into the normal circulatory system

Two veins which converge to form the hepatic portal vein?

Superior mesenteric vein | Splenic vein

Nutrient and oxygen content of blood in hepatic artery?

Nutrient content - low | Oxygen content - high

Nutrient and oxygen content of blood in hepatic portal vein?

Nutrient content - high | Oxygen content - low

Our principle dietary constituents?

Carbohydrate Fat Protein

Dietary constituent with highest energy density?

Fat

Dietary constituent which is our primary energy source?

Carbohydrate

Other substances necessary in our diet outside of principal dietary constituents?

Vitamins Minerals Water

Form of carbohydrate absorbed in the alimentary canal?

Monosaccharides/hexose sugars

Hexose sugars absorbed in alimentary canal?

Glucose Fructose Galactose

Disaccharides are formed by?

Two hexose sugars bonded together

Disaccharides present in our diet?

Lactose Maltose Sucrose

Lactose consists of?

Glucose and galactose

Sucrose consists of?

Glucose and fructose

Maltose consists of?

Two glucose molecules

Form of enzymes which digest disaccharides and their location in the alimentary canal?

Brush border enzymes found in the small intestine

Form of carbohydrate we consume most commonly in our diet?

Polysaccharides

Polysaccharide we consume most commonly in our diet?

Starch

Bonds holding glucose molecules together in starch?

Alpha 1-4 glycosidic bonds

Enzyme which breaks down alpha 1-4 glycosidic bonds?

Amylase

Bonds holding glucose molecules together in cellulose?

Beta 1-4 glycosidic bonds

Enzyme which breaks down beta 1-4 glycosidic bonds?

Cellulase

Polysaccharide which dietary fibre consists of?

Cellulose

Cellulose consumed in our diet is broken down by?

Gut bacteria

Polysaccharide we use to store carbohydrate in our own body?

Glycogen

Site of storage for most of our glycogen?

The liver

Bonds holding glucose molecules together in glycogen?

Alpha 1-4 glycosidic bonds

Lack of which enzyme produces lactose intolerance?

Lactase

Projections of epithelium in small intestine which increase surface area?

Villi

Function of villi in small intestine?

Massively increase surface area available for absorption

Structures holding columnar cells in epithelium of small intestine together?

Tight junctions | Adherens junctions

Number of membranes that molecules must cross to enter blood from lumen of gut tube and the names of these membranes?

Two membranes Apical membrane Basal (basolateral) membrane

Structure required to move water soluble molecules across the membranes of cells in the epithelium of the small intestine?

Transport proteins

Molecule glucose is co-transported with across the apical membrane of epithelial cells in alimentary canal?

Sodium

Transport protein that glucose moves through on apical surface of epithelial cells in alimentary canal?

SGLT1 (sodium glucose transport protein 1)

Transport protein that glucose moves through on basal surface of epithelial cells in alimentary canal?

GLUT-2

Molecule drawn into the blood along with glucose during its transport?

Water

Molecule followed by water into the blood during transport of glucose?

Sodium

Molecule galactose is co-transported with across the apical surface of membrane epithelial cells in alimentary canal?

Sodium

Molecule drawn into the blood along with galactose during its transport?

Water

Structure which moves sodium out of the cell to create gradient required for glucose transport?

Sodium-potassium pump (Na/KATPase)

Normal blood glucose level in humans?

5mmol

Transport proteins fructose moves through during transport from gut lumen to blood?

GLUT-5 | GLUT-2

Hexose sugars which cause water absorption during their transport into the blood?

Glucose | Galactose

Bonds linking amino acids together in protein?

Peptide bonds

Base monomer of proteins?

Amino acids

Name given to small proteins (3-10 amino acids in length)?

Peptides

Enzymes which break down peptide bonds?

Proteases

Enzymes which break peptide bonds in the middle of proteins?

Endoproteases

Enzymes which break peptide bonds on terminal amino acids in proteins?

Exoproteases

Main unit that protein is absorbed as in alimentary canal?

Amino acids

Molecule amino acids are co-transported with during their absorption into the blood from the gut lumen?

Sodium

Molecule which also moves into the blood during the transport of amino acids?

Water

Molecule followed by water during the transport of amino acids into the blood?

Sodium

Molecule peptides are co-transported with during their absorption into the blood from the gut lumen?

Hydrogen ion

Climate maintained at apical surface of epithelial cells in alimentary canal to allow for transport of peptides?

Acid microclimate

Reason for acid microclimate maintained at apical surface of epithelial cells in small intestine?

Provides a supply of hydrogen ions to allow for the transport of peptides across the apical membrane by their co-transporter protein Allows for breakdown of micelles to release fatty acids and monoglycerides to the cells

Enzyme which begins digestion of fat?

Pancreatic lipase

Part of alimentary canal where fat digestion begins?

Duodenum

Products of pancreatic lipase acting on triacylglycerol?

Monoglyceride | 2 fatty acids

Emulsification is?

Breakdown of large lipid goblets into smaller droplets which do not coalesce again

Emulsification requires?

Mechanical breakdown of large lipid goblets | Emulsifying agent

Effect of emulsification on surface area available for action of pancreatic lipase?

Massively increases surface area available

Layer of gut wall responsible for mechanical component of emulsification?

Muscularis externa

Bile salts and phospholipids are what type of molecule?

Amphipathic

Amphipathic molecules have?

Polar component | Non-polar component

Amphipathic molecules prevent re-aggregation of small lipid droplets by?

Binding with them so that their polar component faces externally and repels other droplets that also have polar sections of amphipathic molecules on their external surface

Unit that monogylcerides and fatty acids are transported within in the intestinal lumen?

Micelle

Micelles are composed of?

Monoglyceride Fatty acids Bile salts Phospholipids

Polar component of micelles?

External surface

Non-polar component of micelles?

Internal surface

Site of intestinal lumen where micelles break down?

Acid microclimate

Structure within cells that products of fat digestion immediately enter upon exiting the intestinal lumen?

Smooth endoplasmic reticulum

Molecule formed from products of fat digestion within smooth endoplasmic reticulum?

Triacylglycerol

Extracellular fat droplets released from basolateral membrane of intestinal epithelial cells?

Chylomicron

Structure chylomicrons enter after exiting the cell?

Lacteals of the lymphatic system

System which uptakes and transports chylomicrons after they leave intestinal epithelial cells?

The lymphatic system

2 classes of vitamins in our diet?

Water soluble | Fat soluble

Structure that lipid soluble vitamins are transported in within intestinal lumen?

Micelles

Fat soluble vitamins?

Vitamin A Vitamin D Vitamin E Vitamin K

Water soluble vitamins?

B group vitamins Vitamin C Folic acid

Vitamin which binds with intrinsic factor?

Vitamin B12

Site of intrinsic factor production?

Stomach

Site of vitamin B12 absorption?

Distant ileum

Condition caused by vitamin B12 deficiency?

Pernicious anaemia

Essential function of the stomach?

Production of intrinsic factor

Site of storage of vitamin B12?

The liver

Vitamin B12 is required for?

Maturation of erythrocytes

Site of iron absorption in alimentary canal?

The duodenum

Intracellular iron store?

Ferritin

Iron in blood is bound to?

Transferrin

Method of controlling body's iron status?

Alteration of the quantity of ferritin within cells

Component of our diet controlled at the level of the gut?

Iron

Hyperaemia?

Excessive quantity of iron

Effect of hyperaemia on ferritin levels?

Increase in ferritin levels

Effect of iron deficiency anaemia on ferritin levels?

Decrease in ferritin levels

Colour of feces in hyperaemic patients?

Black

Components of saliva?

``` Water Alpha-amylase Mucins Lysozymes Electrolytes ```

Component of saliva which catalyses breakdown of polysaccharides?

Alpha-amylase

Component of saliva which acts as a lubricant?

Mucins

Component of saliva which softens and dilutes particles?

Water

Main protein component of saliva?

Mucins

Polysaccharides broken down by alpha-amylase?

Starch | Glycogen

Bonds broken down by alpha-amylase?

Alpha 1-4 glycosidic bonds

Bactericidal component of saliva?

Lysozymes

First point in alimentary canal where food begins to become sterilised?

The mouth

Type of glands that salivary glands are?

Exocrine

Tube that parotid gland secretions travel along before entering the mouth?

Parotid duct

Types of alveoli found in salivary glands?

Mucous alveoli | Serous alveoli

Alveoli which secrete alpha-amylase?

Serous alveoli

Alveoli which secrete mucins?

Mucous alveoli

Effect of sympathetic input on salivary secretions?

Increase secretion of viscous, protein rich saliva

Effect of parasympathetic input on salivary secretions?

Increase secretions of profuse watery saliva

Autonomic input producing protein rich saliva?

Sympathetic

Autonomic input producing watery saliva?

Parasympathetic

Part of alimentary canal acting as a conduit between oropharynx and stomach?

The oesophagus

Length of average oesophagus?

25cm

Outermost layer of the oesophagus?

Adventitia

Function of epithelial layer of oesophagus?

Protection from wear and tear

Type of epithelium present in oesophagus?

Stratified squamous non-keratinised epithelium

Type of glands located in submucosa of the oesophagus?

Mucous glands

Parts of the oesophagus consisting of skeletal muscle?

Muscularis externa in its upper third

Parts of the oesophagus consisting of smooth muscle?

Muscularis externa in lower two thirds

Number of oesophageal sphincters and their names?

Two Upper oesophageal sphincter Lower oesophageal sphincter

Function of lower oesophageal sphincter?

Prevent reflux of stomach contents

Function of upper oesophageal sphincter?

Prevent reflux of food during swallowing

Location of swallowing control centre?

Medulla

Structure preventing food from entering trachea during swallowing?

Epiglottis

Voluntary phase of swallowing?

Oral phase

Stage of swallowing where reflexive control takes over?

Pharyngeal phase

Structure preventing food from refluxing once it has entered the oesophagus?

Upper oesophageal sphincter

Type of motility which propels food along oesophagus?

Peristalsis

Nerve causing reflexive relaxation of stomach after swallowing?

Vagus nerve

Part of stomach anatomy which gives it wide range of potential volumes?

Rugae (gastric folds)

Maximum potential volume of stomach?

1500mls (1.5 litres)

Reason we need stomach as a food store?

Prevents dumping syndrome and shock

Fluid that stomach reduces our food into?

Chyme

Functions of gastric acid

Reduction of foodstuffs into chyme | Sterilisation of foodstuffs

Outer layer of the stomach?

Serosa

Location of most oblique muscle in stomach?

Pyloric region

Sphincter between stomach and duodenum?

Pyloric sphincter

Parts of the stomach?

``` Fundus Body Antrum Pyloric region Cardiac region ```

Folds of mucosa and submucosa in stomach?

Rugae (gastric folds)

Three types of cell in gastric gland?

Parietal cell Chief cell Mucous neck cell

Deep invaginations in the epithelium of the stomach?

Gastric pits

Function of the fundus of the stomach?

Storage

The stomach protects itself from corrosion by gastric acid and autodigestion from pepsin by?

Production of thick pH neutral mucus

Chief cells secrete?

Pepsinogen

Parietal cells secrete?

Hydrochloric acid | Intrinsic factor

Inactive form of pepsin?

Pepsinogen

Inactive form of an enzyme?

Zymogen

Function of the antrum of stomach?

Mechanical digestion | Production of gastrin

G cells secrete?

Gastrin

Cells near the entrance to gastric pits secrete?

Protective mucus

Cells which secrete intrinsic factor?

Parietal cells

Molecules required for production of gastric acid?

Hydrogen ions Chloride ions Water

Hormones which influence production of gastric acid?

Histamine Gastrin Acetylcholine Prostaglandins

Effect of gastrin on gastric acid secretion?

Increases gastric acid secretion

Effect of gastrin on proton potassium pump?

Increases action of proton potassium pump

Effect of histamine on gastric acid secretion?

Increases gastric acid secretion

Effect of acetylcholine on gastric acid secretion?

Increases gastric acid secretion

Effect of prostaglandins on gastric acid secretion?

Decreases gastric acid secretion

Three main ways gastric acid secretion can be altered and hormones mediating the mechanisms?

Neurocrine - acetylcholine Endocrine - gastrin Paracrine - histamine

Effect of increased vagus nerve activity on gastric acid secretion?

Increases gastric acid secretion

Effect of gastrin and acetylcholine on enterochromaffin like cells?

Increases secretion of histamine from enterochromaffin like cells

Trigger for release of secretin?

Acid in duodenum

Trigger for release of GIP?

Fat or carbohydrates in duodenum

Action of secretin on gastrin?

Reduces secretion of gastrin | Reduces effect of gastrin on parietal cells

Enterogastrones are released from?

Gland cells in duodenal mucosa

Main enterogastrones?

Cholecystokinin (CCK) Secretin Gastrointestinal inhibitory peptide (GIP)

Trigger for release of enterogastrones?

Acid, hypertonic solutions, monoglycerides or fatty acids in duodenum

Actions of enterogastrones?

Reduce gastric emptying | Reduce gastric acid secretion

Function of enterogastrones?

Prevent excessive buildup of acid in duodenum

Triggers for conversion of pepsinogen to pepsin?

Acidic environment | Presence of pepsin

Action of pepsin on pepsinogen?

Converts it into pepsin

Cells which secrete mucus in the stomach?

Mucus neck cells | Surface epithelial cells

Functions of mucus secreted in the stomach?

Protection from mechanical damage Protection from corrosive gastric acid Protection from auto-digestion by pepsin

Molecule which gives gastric mucus its neutral pH?

Bicarbonate

Direction of movement of peristaltic waves through the stomach?

Body to pyloric region

Site where muscle is thickest in the stomach?

Antrum

Strength of contractions in body of stomach?

Weak

Structure controlling delivery of chyme to duodenum?

Pyloric sphincter

Reasons for controlling delivery of chyme to duodenum?

Prevents dumping syndrome Prevents erosion of epithelium by acidic chyme Allows pancreatic enzymes to become active by preventing buildup of acidic contents

Cells producing slow waves in stomach?

Pacemaker cells

Layer of stomach where slow waves are produced?

Longitudinal layer of muscularis externa

Spontaneous depolarisation and repolarisation of cells in longitudinal muscle of stomach?

Slow waves

Effect of gastrin on stomach contractions?

Increases contractions

Effect of distension of stomach wall on contractions?

Increases contractions

Effect of presence of fat, amino acids, hypertonic solutions or acidic solutions in duodenum on stomach contractions?

Decreases contractions

Messengers responsible for pushing slow waves in stomach to threshold potential?

Gastrin | Acetylcholine

Glands in duodenal submucosa?

Brunner's glands

Brunner's glands secrete?

Bicarbonate

Hormone responsible for bicarbonate release?

Secretin

Function of bicarbonate secretion from Brunner's glands?

Neutralise acidic contents of the stomach within the duodenum

Sources of bicarbonate within duodenum?

Brunner's glands Liver Duct cells of pancreas

Main anatomical parts of pancreas?

``` Tail Body Neck Head Uncinate process ```

Types of glands found in pancreas

Endocrine | Exocrine

Exocrine portion of pancreas?

Acinar cells | Duct cells

Endocrine portion of pancreas?

Islets of Langerhans

Part of pancreas located in curvature of duodenum?

Head

Secretions of endocrine portion of pancreas?

Insulin Glucagon Somatostatin

Site of entry of pancreatic secretions into duodenum?

Hepatopancreatic ampulla (sphincter of Oddi)

Location of hepatopancreatic ampulla within duodenum?

Descending portion of duodenum

Ducts entering duodenum at hepatopancreatic ampulla?

Common bile duct | Main pancreatic duct

Pancreatic duct cells secrete?

Bicarbonate

Pancreatic acinar cells secrete?

Pancreatic digestive enzymes

Method by which pancreas avoids autodigestion?

Pancreatic enzymes are secreted as zymogens

Function of enterokinase?

Converts pancreatic enzymes from zymogens into their active form

Effect of trypsin on pancreatic enzymes?

Converts them from zymogens into their active form

Location of enterokinase?

Brush border of duodenal enterocytes

Site where pancreatic enzymes become active?

Duodenum

Effect of cholecystokinin on pancreatic secretions?

Increases secretion of pancreatic enzymes from acinar cells

Effect of secretin on pancreatic secretions?

Increases secretion of bicarbonate from duct cells

Effect of acidic pH on pancreatic enzymes?

Prevents them from functioning properly

Categories of pancreatic enzymes?

``` Elastases Lipases Phospholipases Alpha-amylase Proteases Nucleases ```

Function of bile?

Emulsification of fats in the alimentary canal

Largest internal organ?

Liver

Major lobes of the liver?

Left | Right

Minor lobes of the liver?

Caudate | Quadrate

Structures forming porta hepatis?

Hepatic artery Hepatic portal vein Hepatic duct

Bile duct is formed by?

Cystic duct | Common hepatic duct

Site of opening of bile duct into duodenum?

Hepatopancreatic ampulla

Structure attaching liver to anterior abdominal wall?

Falciform ligament

Structure attaching liver to underside of diaphragm?

Coronary ligament

Lobes between which porta hepatis is located?

Caudate and quadrate

Functional units of liver?

Lobules

Structures sitting at the corner of each liver lobule?

Branch of hepatic artery Branch of hepatic portal vein Branch of hepatic duct

Structure at the centre of each liver lobule?

Branch of hepatic vein

Hepatic vein empties into?

Inferior vena cava

Functional cells of the liver?

Hepatocytes

Channels between hepatic cords in liver lobules?

Hepatic sinusoids

Bile secreting cells in liver?

Hepatocytes

Direction of blood flow in liver lobules?

External to internal

Vessel carrying blood from alimentary canal into liver?

Hepatic portal vein

Vessels feeding blood into lobules of liver?

Hepatic portal vein | Hepatic artery

Functions of hepatocytes?

Bile synthesis Nutrient storage Nutrient interconversion Detoxification of blood

Fate of excess glucose in our diet?

Conversion to glycogen and storage in hepatocytes

Alimentary function of the liver?

Synthesis of bile salts for emulsification of fat

Components of bile?

``` Bile acids Bile pigments Lecithin Bicarbonate Cholesterol Toxic metals ```

Components of bile synthesised in the liver?

Bile acids Lecithin Cholesterol

Primary bile pigment?

Bilirubin

Source of bilirubin?

Haemoglobin of dead erythrocytes

Duct cells of liver secrete?

Bicarbonate

Bile salts are synthesised from?

Cholesterol

Bile acids are converted to bile salts by?

Conjugation of bile acids with glycine or taurine

Bile acids are conjugated to?

Increase their solubility

Site in alimentary canal where bile salts are reabsorbed?

Distal ileum

Layers of the gallbladder?

Mucosa Muscularis Serosa

Anatomical feature of gallbladder which allows it to expand?

Mucosal folds (rugae)

Bile enters gallbladder by?

Backing up the bile duct when the sphincter of Oddi is closed

Gallbladder concentrates bile by?

Absorbing sodium and water from the bile

Effect of cholecystokinin on gallbladder?

Causes contraction of the muscularis

Trigger for release of bile into duodenum?

Presence of fats in duodenum

Effect of cholecystokinin on sphincter of Oddi?

Relaxation of sphincter of Oddi and opening of hepatopancreatic ampulla

Hormone which increases bicarbonate secretion?

Secretin

Hormones which decrease gastric emptying?

Cholecystokinin | Secretin

Hormone which contracts gallbladder and relaxes sphincter of Oddi?

Cholecystokinin

Hormone which increases secretion of pancreatic enzymes?

Cholecystokinin

Longest part of the alimentary canal?

Small intestine

Functions of the duodenum?

Digestion of foodstuffs Neutralisation of stomach acid Iron absorption

Site of majority of nutrient absorption?

Jejunum

Function of the jejunum?

Absorption of nutrients

Order of parts of small intestine?

Duodenum -> jejunum -> ileum

Functions of the ileum?

Absorption of NaCl Absorption of water Dehydration of chyme

Anatomical features of small intestine which maximise absorptive capabilities?

Plicae circulares Villi Microvilli

Mechanism of water absorption in ileum?

Passively follows absorbed NaCl

Large folds within the small intestine?

Plicae circulares

Functions of plicae circulares?

Increase surface area available for absorption | Produce circular motion to mix chyme with digestive enzymes

Invaginations of surface epithelium between villi?

Crypts of Lieberkuhn

Average lifetime of epithelial cell within small intestine?

Five days

Structures within villi?

Arterial branch of circulation Venous branch of circulation Lacteal

Cells interspersed between columnar epithelial cells in small intestine?

Goblet cells

Anatomical feature which maximally increases surface area of small intestine for absorption?

Microvilli

Function of crypts of Lieberkuhn?

Secrete water into intestinal lumen

Substances absorbed by villi?

``` Water Monosaccharides Peptides Amino acids Fats Minerals Vitamins NaCl ```

Method by which crypts of Lieberkuhn secrete water?

Passively by release of chloride ions into intestinal lumen

Functions of water secreted into intestinal lumen?

Create mucus in conjunction with goblet cells Maintain intestinal contents in liquid state Bring intestinal contents into contact with absorptive surface area Mix intestinal contents with digestive enzymes Dilutes and washes away potentially injurious substances

Molecules co-transported with chloride ions from blood into intestinal epithelial cells?

Sodium | Potassium

Protein channel by which chloride leaves intestinal epithelial cells and enters intestinal lumen?

Cystic fibrosis transmembrane conductance regulator (CFTR)

Two forms of intestinal motility?

Segmentation | Peristalsis

Form of intestinal motility prevalent during a meal?

Segmentation

Motility which clears out small intestine?

Peristalsis

Function of segmentation?

Mixes intestinal contents with digestive enzymes to allow digestion to occur

Cells generating depolarisation to produce segmentation in small intestine?

Pacemaker cells

Frequency of contractions in small intestine is determined by?

Basic electrical rhythm (BER)

Reason for decrease in BER moving distally through small intestine?

Ensures gradual movement of intestinal contents towards colon

Effect of parasympathetic nervous system on contractions in small intestine?

Increases strength of contractions

Effect of sympathetic nervous system on contractions in small intestine?

Decreases strength of contractions

Inputs affecting BER?

None

Form of motility in small intestine which occurs first?

Segmentation

Method by which undigested material is moved out of small intestine?

Peristalsis created by migrating motility complex (MMC)

Pattern of peristaltic activity which moves undigested material out of small intestine?

Migrating motility complex (MMC)

Effect of food in stomach on migrating motility complex?

Cessates migrating motility complex

Hormone which initiates migrating motility complex?

Motilin

Direction of movement of contents of small intestine under migrating motility complex?

Oesophagus to rectum

Effect of chyme entering caecum on ileocaecal valve?

Contracts ileocaecal valve

Order of parts of large intestine?

``` Caecum Ascending colon Transverse colon Descending colon Sigmoid colon Rectum Anal canal ```

Small projection of tissue coming from caecum?

Vermiform appendix

Tissue within appendix?

Lymphoid tissue

Layer of muscularis externa in colon which is incomplete?

Longitudinal layer

Bands of smooth muscle tissue within colon?

Teniae coli

Pouches/sacculations in colon?

Haustra

Epithelium within colon?

Simple columnar epithelium

Cells found within crypts of colon?

Goblet cells

Function of mucus secreted in colon?

Lubricate the colon for smooth passage of fecal material

Type of muscle within external anal sphincter?

Skeletal muscle

Epithelium present within anal canal?

Simple columnar epithelium -> stratified squamous epithelium

Type of muscle within internal anal sphincter?

Smooth muscle

Anal sphincter under voluntary control?

External anal sphincter

Substances absorbed by colon?

Sodium | Water

Material digested by bacterial colonies within colon?

Cellulose

Nutrient gained from bacterial fermentation in colon?

Vitamin K

Trigger for defeacation reflex?

Distension of rectum by fecal material

Nerve controlling defeacation reflex?

Pelvic splanchnic nerve

Autonomic control governing defeacation reflex?

Parasympathetic

Mechanism causing diarrhoea during enteric infection?

Increased secretion of chloride ions from crypt cells

Intracellular messengers increased by bacterial enterotoxins?

cAMP cGMP Calcium

Components of oral rehydration therapy?

Glucose Sodium Water

Mechanism of oral rehydration therapy?

Increased intake of glucose and sodium leads to increased water absorption by villus cells due to pathways of absorption