Diabetes Mellitus Classification and Key Concepts
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Questions and Answers

Which of the following correctly classifies the types of diabetes mellitus?

  • Type 1 diabetes, Type 4 diabetes, Secondary diabetes
  • Type 1 diabetes, Type 2 diabetes, Secondary diabetes (correct)
  • Type 2 diabetes, Type 3 diabetes, Secondary diabetes
  • Type 1 diabetes, Type 2 diabetes, Gestational diabetes

    • Insulin increases blood glucose levels in the body.

    False

    What hormone is primarily responsible for lowering blood glucose levels?

    Insulin

    The main source of metabolic fuel for the brain under normal conditions is _____ .

    <p>glucose</p> Signup and view all the answers

    What is the estimated global prevalence of diabetes mellitus?

    <p>537 million people</p> Signup and view all the answers

    What is the blood glucose level range typically observed in healthy individuals?

    <p>3.5-8 mmol/L</p> Signup and view all the answers

    Match the following processes with their correct descriptions:

    <p>Glycogenolysis = Breakdown of glycogen stores to release glucose Gluconeogenesis = Formation of new glucose from non-carbohydrate sources Insulin = Hormone that lowers blood glucose levels Glucagon = Hormone that raises blood glucose levels</p> Signup and view all the answers

    Diabetes mellitus is solely caused by insulin resistance.

    <p>False</p> Signup and view all the answers

    Which glucose transporter is specifically associated with muscle and adipose tissue?

    <p>GLUT-4</p> Signup and view all the answers

    GLUT-5 is an insulin-dependent glucose transporter.

    <p>False</p> Signup and view all the answers

    What process involves the formation of glucose from non-carbohydrate molecules?

    <p>Gluconeogenesis</p> Signup and view all the answers

    GLUT-___ is primarily found in the brain and neurons.

    <p>3</p> Signup and view all the answers

    Match the following GLUT transporters with their tissue location:

    <p>GLUT-1 = Most cells GLUT-2 = Liver, pancreatic B cells GLUT-3 = Brain (neurons) GLUT-4 = Muscle and adipose tissue</p> Signup and view all the answers

    Which of the following statements about glucose homeostasis is correct?

    <p>Hyperglycemia can lead to cellular damage.</p> Signup and view all the answers

    Hypoglycemia can be life-threatening.

    <p>True</p> Signup and view all the answers

    What is the stored form of glucose in the liver and muscle called?

    <p>Glycogen</p> Signup and view all the answers

    Which hormone is primarily responsible for increasing plasma glucose levels?

    <p>Glucagon</p> Signup and view all the answers

    Insulin was first identified as a pancreatic hormone in the early 1900s.

    <p>True</p> Signup and view all the answers

    Who were the scientists that discovered insulin?

    <p>Frederick Banting and Charles Best</p> Signup and view all the answers

    The process of breaking down glycogen to release glucose is called ______.

    <p>glycogenolysis</p> Signup and view all the answers

    Match the following hormones with their effects on plasma glucose levels:

    <p>Insulin = Decreases plasma glucose Glucagon = Increases plasma glucose Cortisol = Increases plasma glucose Growth hormone = Increases plasma glucose</p> Signup and view all the answers

    Which of the following is NOT a hormone that decreases plasma glucose?

    <p>Glucagon</p> Signup and view all the answers

    Cortisol plays a role in decreasing plasma glucose levels.

    <p>False</p> Signup and view all the answers

    What is the first step in the process that stimulates insulin release from beta-cells?

    <p>Increase in plasma glucose</p> Signup and view all the answers

    What stimulates the opening of voltage-gated calcium channels?

    <p>Depolarization</p> Signup and view all the answers

    Insulin secretion consists of a single steady phase regardless of blood glucose levels.

    <p>False</p> Signup and view all the answers

    What is the main action of insulin on glucose?

    <p>Facilitates glucose transport into cells</p> Signup and view all the answers

    Insulin promotes the storage of fat in adipose cells by converting excess glucose to _____ and inhibits the release of free-fatty acids.

    <p>triglycerides</p> Signup and view all the answers

    Match the following actions of insulin with the correct descriptions:

    <p>Facilitates glucose transport = Releases GLUT-4 transporters Promotes glycogen synthesis = Increases glycogen synthase activity Inhibits gluconeogenesis = Reduces available amino acids Promotes fatty acid synthesis = Converts excess glucose to fatty acids</p> Signup and view all the answers

    Which of the following is NOT a molecule that stimulates insulin secretion?

    <p>Adrenaline</p> Signup and view all the answers

    Insulin release is associated with energy deficiency in the body.

    <p>False</p> Signup and view all the answers

    What role does insulin play in the liver regarding glucose?

    <p>Inactivates liver phosphorylase and increases glucokinase activity</p> Signup and view all the answers

    What effect do incretins have on insulin secretion?

    <p>Augment insulin secretion in response to oral glucose</p> Signup and view all the answers

    Type 2 diabetes mellitus is primarily caused by an autoimmune attack on β-cells.

    <p>False</p> Signup and view all the answers

    What is chronic hyperglycaemia a characteristic of?

    <p>Diabetes Mellitus</p> Signup and view all the answers

    Cortisol promotes ________ and inhibits glucose transport.

    <p>gluconeogenesis</p> Signup and view all the answers

    Match the following diabetes types with their characteristics:

    <p>Type 1 Diabetes = Autoimmune destruction of β-cells Type 2 Diabetes = Insulin resistance with possible insulin deficiency Secondary Diabetes = Diabetes due to drugs or genetic defects Pre-diabetic conditions = Impaired fasting glycaemia or glucose tolerance</p> Signup and view all the answers

    Which of the following best describes glucagon's role in the body?

    <p>Facilitates lipolysis and proteolysis</p> Signup and view all the answers

    Insulin secretion is inhibited when catecholamines are released.

    <p>True</p> Signup and view all the answers

    What is the main impact of increased free fatty acids on insulin production?

    <p>Increases insulin production</p> Signup and view all the answers

    What is a common cause of osmotic diarrhea?

    <p>Nutrient maldigestion</p> Signup and view all the answers

    Motility-related diarrhea reduces the time available for absorption in the gastrointestinal tract.

    <p>True</p> Signup and view all the answers

    Name one class of drugs used to treat disorders of GI motility.

    <p>Purgatives or Anti-diarrhoeal agents</p> Signup and view all the answers

    Anti-diarrhoeal agents include _____ agents and opioids.

    <p>anti-motility</p> Signup and view all the answers

    Match the type of diarrhea with its cause:

    <p>Osmotic diarrhea = Maldigestion Motility-related diarrhea = High GI motility Inflammatory diarrhea = Mucosal damage Diarrhea due to infection = Bacterial/viral/parasite</p> Signup and view all the answers

    What is a notable side effect of long-term use of loperamide?

    <p>Constipation</p> Signup and view all the answers

    Loperamide decreases the activity of circular smooth muscles.

    <p>False</p> Signup and view all the answers

    What is one action of loperamide on colonic motility?

    <p>Increases segmented contractions or decreases peristaltic activity</p> Signup and view all the answers

    What is the time of action for bulk laxatives?

    <p>1-3 days</p> Signup and view all the answers

    Osmotic laxatives work by promoting the movement of fluid across the intestinal wall into the GI tract lumen.

    <p>True</p> Signup and view all the answers

    Name one example of a saline purgative.

    <p>Magnesium sulphate</p> Signup and view all the answers

    Colonic bacteria convert lactulose into its monosaccharide components, which are NOT absorbed into the blood, and generate ____ acid and acetic acid.

    <p>lactic</p> Signup and view all the answers

    Match the following types of laxatives with their descriptions:

    <p>Bulk laxatives = Polysaccharide polymers that retain water Osmotic laxatives = Promote movement of fluid via osmosis Stimulant purgatives = Stimulate intestinal nerve endings to induce motility Faecal softeners = Help incorporate water into the stool</p> Signup and view all the answers

    Which of the following is a class of anti-diarrhoeal agents?

    <p>Anti-motility agents</p> Signup and view all the answers

    Lactulose acts immediately within 1 hour to treat chronic constipation.

    <p>False</p> Signup and view all the answers

    What is a common use for magnesium hydroxide?

    <p>Bowel prep prior to procedures</p> Signup and view all the answers

    What is the action time for faecal softeners like docusate?

    <p>3-5 days</p> Signup and view all the answers

    Stimulant purgatives such as bisacodyl should only be used for long-term treatment of constipation.

    <p>False</p> Signup and view all the answers

    What medical consequences can arise from chronic use of stimulant laxatives?

    <p>Fluid and electrolyte imbalance</p> Signup and view all the answers

    Senna works by releasing free _____ derivatives in the colon.

    <p>anthracene</p> Signup and view all the answers

    Match the following types of laxatives with their descriptions:

    <p>Docusate = Faecal softener Bisacodyl = Stimulant purgative Senna = Natural laxative derived from plants Arachis oil enema = Oil-based laxative</p> Signup and view all the answers

    What is a potential sign of chronic laxative dependency?

    <p>Bloating and abdominal pain</p> Signup and view all the answers

    The main cause of diarrhoea is decreased gastrointestinal motility.

    <p>False</p> Signup and view all the answers

    What term describes anatomical and physiological changes in the colon due to chronic stimulant laxative use?

    <p>Cathartic Colon</p> Signup and view all the answers

    What is the primary role of the ileocaecal valve?

    <p>Prevents back-flow of faecal contents from the colon</p> Signup and view all the answers

    The ileocaecal valve is a two-way valve that allows free movement of contents between the ileum and the colon.

    <p>False</p> Signup and view all the answers

    What mechanism controls the movement of Na+ into the epithelial cell of the colon?

    <p>Na+ channel</p> Signup and view all the answers

    The action of water crossing the epithelium occurs via a _______ route.

    <p>transcellular</p> Signup and view all the answers

    Match the following components of electrolyte transport in the colon with their functions:

    <p>Na+-K+ ATPase = Exchanges Na+ and K+ across the cell membrane K+ channel = Facilitates K+ exit from the cell Na+ channel = Allows Na+ entry into the cell Transcellular route = Method for water transport across the epithelium</p> Signup and view all the answers

    Which ions are involved in the transport mechanisms described in the content?

    <p>Na+ and K+</p> Signup and view all the answers

    K+ enters the epithelial cell of the colon through a Na+-K+ ATPase.

    <p>True</p> Signup and view all the answers

    What initiates mass movements in the colon?

    <p>Gastrin</p> Signup and view all the answers

    The anal canal is normally filled with feces.

    <p>False</p> Signup and view all the answers

    What is the primary component of faeces?

    <p>3/4 water</p> Signup and view all the answers

    What pushes the ileocaecal valve open and shut?

    <p>ileocaecal sphincter</p> Signup and view all the answers

    What are the two types of anal sphincters?

    <p>internal anal sphincter and external anal sphincter</p> Signup and view all the answers

    The Valsalva manoeuvre involves forced expiration with an open glottis.

    <p>False</p> Signup and view all the answers

    Mass movements occur _____ times a day.

    <p>1-3</p> Signup and view all the answers

    Which vitamin is synthesized by intestinal bacteria?

    <p>Vitamin K</p> Signup and view all the answers

    Match the following components with their functions:

    <p>Gastrocolic Reflex = Initiates mass movements in the colon Defaecation Reflex = Triggers the passage of feces Internal Anal Sphincter = Involuntary control over feces External Anal Sphincter = Voluntary control over feces</p> Signup and view all the answers

    The brown color of faeces is primarily due to derivatives of _______.

    <p>bilirubin</p> Signup and view all the answers

    Match the components of faeces with their respective percentages:

    <p>Water = 75% Dead bacteria = 30% Fat = 10-20% Protein = 2-3%</p> Signup and view all the answers

    Which part of the digestive system pushes colonic contents into the rectum?

    <p>Sigmoid colon</p> Signup and view all the answers

    The defaecation reflex is a response to stimulation of the rectal wall.

    <p>True</p> Signup and view all the answers

    Which action occurs first during defaecation?

    <p>Contraction of the rectum</p> Signup and view all the answers

    Intestinal bacteria help degrade digestive enzymes.

    <p>True</p> Signup and view all the answers

    How many times do mass movements typically occur in a day?

    <p>1 to 3 times</p> Signup and view all the answers

    What is the primary action of the external anal sphincter during voluntary defaecation?

    <p>Relaxation</p> Signup and view all the answers

    What causes the colon to bulge into ovoid segments?

    <p>Haustral contractions of the taeniae coli and circular muscle layer</p> Signup and view all the answers

    Haustral contractions primarily occur in the distal colon.

    <p>False</p> Signup and view all the answers

    How many times a day do mass movements typically occur?

    <p>1-3 times</p> Signup and view all the answers

    The process of moving a bolus along the length of the gastrointestinal tract is called ______.

    <p>peristalsis</p> Signup and view all the answers

    Match the following types of movement with their descriptions:

    <p>Haustral contractions = Mixing contents in the proximal colon Mass movements = Propel contents from transverse to sigmoid colon Peristalsis = Move a bolus through the GI tract Segmentation = Segmented contractions for mixing</p> Signup and view all the answers

    What is the primary role of haustral contractions?

    <p>Facilitating water absorption</p> Signup and view all the answers

    Peristalsis is a series of strong contractions that only occur in the stomach.

    <p>False</p> Signup and view all the answers

    The colon experiences contractions that cause it to bulge into segments, known as ______.

    <p>haustrae</p> Signup and view all the answers

    Which disease is characterized by inflammation in the lining of the colon, leading to symptoms such as diarrhea and abdominal pain?

    <p>Ulcerative Colitis</p> Signup and view all the answers

    Electrolyte transport in the intestine varies depending on the segment of the intestine being examined.

    <p>True</p> Signup and view all the answers

    What is the primary driving force for water absorption in the intestines?

    <p>Movement of Na+ (sodium)</p> Signup and view all the answers

    The ______ disease is known to cause tremendous loss of fluid in the body.

    <p>bacterial</p> Signup and view all the answers

    Match the following processes with their descriptions:

    <p>Paracellular route = Water crosses via tight junctions between cells Transcellular route = Water crosses through cells Active transport = Movement of substances against concentration gradient Osmosis = Movement of water following osmotic gradients</p> Signup and view all the answers

    What role does the Na+/K+ ATPase play in fluid balance within the GI tract?

    <p>It aids in the absorption of sodium and subsequently water.</p> Signup and view all the answers

    Water absorption in the intestines occurs solely through the transcellular route.

    <p>False</p> Signup and view all the answers

    Name one mechanism through which water crosses the intestinal epithelium.

    <p>Paracellular route or Transcellular route</p> Signup and view all the answers

    What percentage of the cardiac output does the liver receive?

    <p>25%</p> Signup and view all the answers

    The liver only receives arterial blood through the hepatic artery.

    <p>False</p> Signup and view all the answers

    What is the primary function of bile salts?

    <p>Emulsification of fats</p> Signup and view all the answers

    The liver weighs approximately _____ kg.

    <p>1.4</p> Signup and view all the answers

    Match the following major cell types of the liver with their functions:

    <p>Hepatocytes = Main functional cells of the liver Kupffer cells = Liver macrophages Cholangiocytes = Cells lining the bile ducts Stellate cells = Storage of vitamin A and involved in fibrosis</p> Signup and view all the answers

    Which of the following is a component of bile?

    <p>Bile salts</p> Signup and view all the answers

    The hepatic portal vein carries arterial blood to the liver.

    <p>False</p> Signup and view all the answers

    What is the role of the hepatic portal vein?

    <p>To carry venous blood from the gastrointestinal tract to the liver</p> Signup and view all the answers

    What is the primary physiological role of bile salts in the small intestine?

    <p>Emulsify fats</p> Signup and view all the answers

    Cholangiocytes are responsible for secreting bile salts and cholesterol.

    <p>False</p> Signup and view all the answers

    List two major components of bile.

    <p>Bile salts and lecithin</p> Signup and view all the answers

    Bicarbonate in bile helps to ________ acid in the duodenum.

    <p>neutralize</p> Signup and view all the answers

    Match the following bile components with their functions:

    <p>Bile salts = Solubilize fats Lecithin = Phospholipid for fat emulsification Cholesterol = Component of cell membranes Bile pigments = Waste product from hemoglobin breakdown</p> Signup and view all the answers

    Which of the following is NOT a component of bile?

    <p>Glucose</p> Signup and view all the answers

    Bile is produced by the gall bladder.

    <p>False</p> Signup and view all the answers

    What substance does the gall bladder primarily store?

    <p>Bile</p> Signup and view all the answers

    What percentage of bile salts is continuously recycled via the enterohepatic circulation?

    <p>95%</p> Signup and view all the answers

    Bile salts are only responsible for the elimination of cholesterol and do not aid in lipid digestion.

    <p>False</p> Signup and view all the answers

    Name the primary dietary component whose absorption may be impaired due to damage to the ileum.

    <p>fats</p> Signup and view all the answers

    The liver synthesizes new bile salts to replace the _____ lost in the feces.

    <p>5%</p> Signup and view all the answers

    Match the types of bile acids with their origin:

    <p>Primary bile acids = Sourced directly from cholesterol Secondary bile acids = Formed from primary bile acids by intestinal bacteria Conjugated bile salts = Combined with amino acids like taurine or glycine Bile salts = Participating in fat digestion and absorption</p> Signup and view all the answers

    What is one of the main functions of bile salts during digestion?

    <p>Emulsification of dietary lipids</p> Signup and view all the answers

    The liver plays no role in synthesizing bile salts.

    <p>False</p> Signup and view all the answers

    Explain why damage to the ileum could cause steatorrhoea.

    <p>It impairs the absorption of fats.</p> Signup and view all the answers

    What percentage of cholesterol is synthesized within the body?

    <p>85%</p> Signup and view all the answers

    Cholesterol serves as a precursor for steroid hormones.

    <p>True</p> Signup and view all the answers

    What is the main organ responsible for cholesterol synthesis?

    <p>liver</p> Signup and view all the answers

    Cholesterol is transported in plasma in complexes with __________.

    <p>lipoproteins</p> Signup and view all the answers

    Match the following roles of the liver with their corresponding functions:

    <p>Synthesizes cholesterol = From acetyl CoA Synthesizes lipoproteins = Transport cholesterol Exports cholesterol = To body cells and bile Utilizes cholesterol = For bile salts synthesis</p> Signup and view all the answers

    Which of the following is NOT a function of cholesterol?

    <p>Energy source for muscles</p> Signup and view all the answers

    Cholesterol is fully derived from dietary sources.

    <p>False</p> Signup and view all the answers

    What happens to excess cholesterol in the plasma?

    <p>exported to bile for excretion</p> Signup and view all the answers

    What digestive function do bile salts primarily serve?

    <p>They emulsify fats into smaller droplets.</p> Signup and view all the answers

    Damage to the ileum can lead to malabsorption of dietary fats.

    <p>True</p> Signup and view all the answers

    What condition results from the excessive loss of dietary fat in feces?

    <p>Steatorrhea</p> Signup and view all the answers

    The terminal ileum is crucial for recycling bile salts through the ________ circulation.

    <p>enterohepatic</p> Signup and view all the answers

    Which other dietary component is likely to be impaired due to bile salt deficiency?

    <p>Fat soluble vitamins</p> Signup and view all the answers

    Match the following conditions with their consequences:

    <p>Ileal resection = Impaired bile salt recycling Bile salt deficiency = Steatorrhea Fat malabsorption = Fatty stools Intestinal epithelial damage = Reduced nutrient absorption</p> Signup and view all the answers

    The liver can create sufficient bile salts solely from scratch without recycling.

    <p>False</p> Signup and view all the answers

    What are micelles responsible for in fat digestion?

    <p>They present fat digestion products to the intestinal epithelial cells for absorption.</p> Signup and view all the answers

    Which ethical principle emphasizes the importance of treating patients as individuals and respecting their dignity?

    <p>Respect</p> Signup and view all the answers

    The NICE guidance mandates that practitioners must apply its recommendations without exception.

    <p>False</p> Signup and view all the answers

    What is one of the elements of dignity in care?

    <p>Respect</p> Signup and view all the answers

    Person-centred care requires building a relationship with patients through effective _____ .

    <p>communication</p> Signup and view all the answers

    Match the following components of person-centred care with their descriptions:

    <p>Respect = Valuing individual worth Autonomy = Right to make personal choices Care = Actions that promote well-being Dignity = Inherent worthiness of the individual</p> Signup and view all the answers

    What is a potential consequence of implementing person-centred care effectively?

    <p>Better patient outcomes</p> Signup and view all the answers

    The core ethical values of medicine support the practice of person-centred care.

    <p>True</p> Signup and view all the answers

    According to the concept of dignity in care, what does it mean to be treated like someone?

    <p>Being valued and respected as an individual</p> Signup and view all the answers

    Study Notes

    Osmotic Diarrhoea

    • Caused by a heavy osmotic load within the gut lumen
    • Occurs in maldigestion conditions like celiac disease
    • Nutrients remain in the gut lumen, drawing excess water
    • Results from abnormally high gastrointestinal (GI) motility
    • Shortens the time available for absorption
    • Can occur due to diabetic neuropathy

    Inflammatory Diarrhoea

    • Damage to the mucosal lining or brush border
    • Leads to passive loss of protein-rich fluids
    • Decreases the ability to absorb fluids
    • Caused by bacterial, viral, or parasitic infections, or autoimmune problems
    • An example is inflammatory bowel disease

    Classes of Drugs Used to Treat Disorders of GI Motility

    • Purgatives
      • Bulk laxatives
      • Osmotic laxatives
      • Faecal softeners
      • Stimulant purgatives
    • Anti-diarrhoeal agents
      • Anti-motility agents

    Anti-Motility Agents

    • Examples: Loperamide (Imodium®), codeine
    • Loperamide has a selective action on the GI tract
    • Acts on µ-opioid receptors in the myenteric plexus and intestinal smooth muscle
    • Increases activity of the circular smooth muscles
    • Decreases activity of the longitudinal muscles

    Effect of Loperamide on Colonic Motility

    • Increases segmented (haustral) contractions of the proximal colon
    • This leads to enhanced mixing and water reabsorption
    • Reduces peristaltic activity in the distal colon
    • Diminishes propulsive mass movements
    • Contracts the pyloric, ileocaecal, and anal sphincters

    Loperamide Usage & Side Effects

    • Symptomatic treatment of acute uncomplicated diarrhoea in adults
    • Used as an adjunct to rehydration therapy
    • Chronic use can lead to constipation, abdominal cramps, and dizziness
    • Paralytic ileus is a possible side effect
    • Caution: Do not use in young children

    Bulk Laxatives

    • Polysaccharide polymers that are not broken down during digestion
    • Retain water in the GI lumen, softening and increasing faecal bulk
    • Promotes increased gut motility
    • Examples: methylcellulose, plant gums (bran, agar, guar, or ispaghula husk)

    Osmotic Laxatives

    • Poorly absorbed solutes
    • Promote movement of fluid by osmosis into the GI tract lumen
    • Accelerates small intestine transit, leading to increased fluid entering the colon
    • Distension results in purgation

    Saline Purgatives

    • Examples: magnesium sulphate, magnesium hydroxide
    • Potent and rapid action (1-2 hours)
    • Produce watery evacuation
    • Usage: Bowel preparation prior to procedures

    Macrogols

    • Inert polymers of ethylene glycol
    • Sequester fluid in the bowel
    • Usage:
      • Treatment of faecal impaction in children
      • Long-term management of chronic constipation

    Lactulose

    • Semi-synthetic disaccharide of fructose and galactose
    • Colon bacteria convert it to its component monosaccharides, which are not absorbed
    • Fermentation yields lactic acid and acetic acid - function as osmotic laxatives
    • Act within 1-3 days
    • Usage: Chronic constipation, opioid-associated constipation

    Faecal Softeners

    • Examples: docusate, arachis oil enema
    • Anionic surfactants that lower surface tension at the oil-water interface
    • Allow water or fats to enter the stool, softening faecal matter
    • Slower action, requiring 3-5 days to keep stools soft
    • Usage: Constipation and rectal fissures or haemorrhoids

    Stimulant Purgatives

    • Stimulate colonic motility

    Bisacodyl

    • Typically administered as a suppository
    • Stimulates the rectal mucosa, resulting in mass movements and defaecation in 15-30 minutes
    • Short courses are recommended
    • Used to treat opioid-associated constipation

    Senna

    • Contains anthracene derivatives combined with sugars
    • Passes unchanged into the colon, where bacterial action releases free anthracene derivatives
    • Anthracene derivatives are absorbed by the intestinal mucosa and directly affect the myenteric plexus

    Effect of Senna on Colonic Motility

    • Strain gauge recordings demonstrate its effect on different segments of the colon
    • Proximal colon: Reduced motility
    • Mid colon: Increased motility
    • Distal colon: Increased motility

    “Cathartic Colon”

    • Anatomical and physiological changes in the colon that occur with chronic stimulant laxative use (>3 times/week for at least 1 year)
    • Leads to laxative dependency and tachyphylaxis (higher doses needed)
    • Serious medical consequences such as fluid and electrolyte imbalance
    • Signs and symptoms: bloating, fullness, abdominal pain, incomplete faecal evacuation

    Prevention of Constipation

    • Easier to prevent than treat
    • Osmotic laxative relief should be followed by prevention using increased fibre
    • Combine osmotic, bulk-forming and stimulant agents for chronic opioid use

    Diarrhoea

    • “Diarrhoia” meaning “a flowing through”
    • Frequent watery, loose bowel movements
    • Numerous causes including infectious agents, toxins, anxiety, and drugs
    • Major cause of death in malnourished infants
    • Involves increased GI motility and secretion, decreased absorption
    • Leads to fluid and electrolyte loss

    Types of Diarrhoea

    • Secretory diarrhoea
      • Increased active secretion or inhibition of absorption (e.g. cholera)

    Large Intestine Function

    • Absorbs water and electrolytes
    • Absorbs nutrients from undigested food
    • Forms and stores faeces
    • Houses bacteria that aid in digestion

    Mechanisms of Water Reabsorption in the Large Intestine

    • Sodium (Na+) is actively transported from the lumen of the large intestine into the epithelial cells
    • Water passively follows the osmotic gradient created by Na+ movement
    • This process is driven by the Na+/K+ ATPase pump which creates a concentration gradient for Na+ across the cell membrane
    • Water movement is primarily paracellular in the jejunum, but transcellular in the colon

    Colon Movements

    • Taenia coli are three bands of smooth muscle that run along the length of the colon, allowing it to contract and bulge outwards into ovoid segments called haustrae.
    • Peristaltic waves move contents along the colon
    • Haustral contractions (segmented) mix the contents of the proximal colon
    • This facilitates water absorption

    Defecation

    • The gastrocolic reflex is initiated by gastrin and the autonomic nervous system
    • It pushes colonic contents into the rectum, triggering the defecation reflex
    • The defecation reflex is mediated by mechanoreceptors in the rectal wall and involves: contraction of the rectum, relaxation of the internal anal sphincter, increased peristaltic activity in the sigmoid colon, and relaxation of the external anal sphincter
    • Voluntary control of defecation involves the Valsalva maneuver

    Intestinal Bacteria

    • The large intestine harbors a large population of anaerobic bacteria that serve several physiologically useful functions:
      • Provide immunity against common bacteria
      • Convert bilirubin to urobilinogens
      • Form secondary bile acids
      • Degrade digestive enzymes
      • Digest mucus
      • Synthesize certain vitamins (e.g. vitamin K)
      • Metabolize undigested polysaccharides

    Inflammatory Bowel Disease

    • Inflammation of the lining of the colon causing diarrhea, blood in the stool, abdominal pain and weight loss

    Cholera

    • Watery diarrhea: Cholera is a bacterial disease that is known to cause tremendous loss of fluid.

    Liver: Location & Size

    • Located mainly in the upper right quadrant of the abdomen
    • Weighs approximately 1.4 kilograms

    Liver: Blood Supply

    • Receives 25% of cardiac output
    • Blood supply comes from hepatic portal vein (venous) and proper hepatic artery (arterial)
    • Hepatic portal vein carries venous blood from the stomach, small intestine, large intestine, pancreas, and spleen

    Liver: Organization & Functions

    • Major cell types: Hepatocytes (secrete bile salts, cholesterol, lecithin, and bile pigments), Cholangiocytes (secrete bicarbonate and water)
    • Major functions:
      • Production and secretion of bile
      • Metabolism of carbohydrates, proteins, and fats
      • Detoxification of drugs and other harmful substances
      • Synthesis of plasma proteins
      • Storage of glycogen, vitamins, and minerals
      • Regulation of blood volume and composition
      • Production of clotting factors

    Bile

    • Bile is stored and concentrated in the gallbladder.
    • Bile contains:
      • Bile salts (bile acids conjugated with taurine)
      • Lecithin
      • Bicarbonate and other salts
      • Cholesterol
      • Bile pigments and small amounts of other metabolic end-products
      • Trace metals

    Bile: Functions

    • Solubilize fat in the small intestine: Bile salts emulsify dietary lipids, making them accessible to pancreatic lipases for digestion.
    • Neutralize acid in the duodenum: Bicarbonate in bile helps neutralize the acidic chyme coming from the stomach.
    • Eliminate cholesterol: Bile salts help eliminate cholesterol from the body.
    • Prevent cholesterol precipitation in the gallbladder: Bile salts help keep cholesterol dissolved in bile, preventing the formation of gallstones.
    • Facilitate the absorption of fat-soluble vitamins: Bile salts help solubilize fat-soluble vitamins, making them easier to absorb in the small intestine.

    Enterohepatic Circulation

    • 95% of bile salts are continuously recycled via the enterohepatic circulation.
    • Bile salts are released into the small intestine, reabsorbed, and returned to the liver for reuse.
    • 5% of bile salts are lost in the feces, and the liver synthesizes new bile salts to replace them.

    Effects of Ileal Damage

    • Ileal resection or Crohn's disease can lead to steatorrhea (fatty stools) due to impaired bile salt reabsorption.
    • Damage to the ileum leads to a decrease in the bile salt pool, which impairs fat digestion and absorption.
    • Impaired bile salt reabsorption also affects the absorption of fat-soluble vitamins (A, D, E, and K) because they follow the same pathway for absorption as fat digestion products.

    Cholesterol Processing

    • The liver plays a key role in cholesterol processing:
      • Synthesizes cholesterol from acetyl CoA.
      • Synthesizes lipoproteins, which transport cholesterol in plasma.
      • Exports cholesterol via circulation to other cells for synthesis of key products like steroid hormones.
      • Utilizes cholesterol for the synthesis of bile salts
      • Extracts excess cholesterol from the plasma.
      • Exports excess cholesterol in bile for excretion in feces.

    Synthesis of Plasma Proteins

    • The liver synthesizes major plasma proteins, including:
      • Albumin (maintains blood osmotic pressure)
      • Coagulation factors (involved in hemostasis and fibrinolysis)
      • Carriage proteins (transport various substances in the blood)
      • Pro-hormones
      • Apolipoproteins (help transport lipids in the blood)

    Person-Centred Care

    • Person-centered care is a core ethical principle in healthcare, reflected in various professional guidelines, including those from the GMC and NICE.
    • The GMC emphasizes treating patients as individuals, respecting their dignity, and working in partnership with them.
    • NICE guidance emphasizes considering individual needs, preferences, and values alongside its recommendations.
    • Healthcare professionals are expected to fully account for NICE guidelines but ultimately make decisions appropriate to individual patient circumstances.

    Ethical Principles and Values

    • Core ethical values in medicine, such as respect, autonomy, care, and dignity, are directly tied to person-centered care.
    • Dignity is a complex concept encompassing esteem, respect, and self-respect. It's about providing care that promotes and doesn't undermine a person's self-worth, regardless of differences.

    Dignity in Care

    • Dignity in care encompasses elements of respect, privacy, self-esteem, freedom from unnecessary pain, and autonomy.
    • Considering consequences of person-centered care can lead to better patient outcomes, fewer complaints, reduced risk of litigation, and increased trust in the medical profession.

    Ethics and Person-Centred Care in Practice

    • Person-centered care requires building a relationship with patients.
    • Effective consultations are the first step in building this relationship.

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    Test your knowledge on the classification of diabetes mellitus and the hormones involved in glucose regulation. This quiz covers various aspects of glucose homeostasis, including transporters and metabolic processes. Perfect for students of health science or anyone interested in understanding diabetes.

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