Alimnetary system
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Questions and Answers

What type of receptors detect stretch and stimulate contractions in the gut?

  • Osmoreceptors
  • Chemoreceptors
  • Mechanoreceptors (correct)
  • Gastrin receptors

    • What type of hormone is secreted by the stomach and pancreas to stimulate acid and pepsinogen secretion?

  • Secretin
  • Insulin
  • Gastrin (correct)
  • Cholecystokinin

    • What is the term for hormones that are secreted by nerves?

  • Neurocrine (correct)
  • Endocrine
  • Autocrine
  • Paracrine

    • What is the function of the ventro medial area of the hypothalamus?

    <p>Satiety centre</p> Signup and view all the answers

    What is the term for hormones that are secreted by adjacent cells?

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

    What is the term for the phase of digestion that occurs in the small intestine?

    <p>Intestinal phase</p> Signup and view all the answers

    What is the function of Motilia?

    <p>Increases motility and clears the tract between meals</p> Signup and view all the answers

    What is the term for hormones that are secreted by the gut cells and neurons to decrease glucagon and increase insulin secretion?

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

    What is the term for the area of the brain that regulates appetite and satiety?

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

    What is the term for the surgical procedure that reduces stomach size and dietary intake?

    <p>Gastric band</p> Signup and view all the answers

    Which enzyme is responsible for the digestion of DNA and RNA?

    <p>Nucleic acid enzymes</p> Signup and view all the answers

    What is the primary function of Brunner glands in the duodenum?

    <p>Secretion of alkaline mucus</p> Signup and view all the answers

    What is the primary adaptation of the mucosa in the small intestine that increases surface area?

    <p>All of the above</p> Signup and view all the answers

    Which part of the large intestine is responsible for the fermentation of complex carbohydrates?

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

    What is the primary function of the rectum?

    <p>Storage of faecal mass</p> Signup and view all the answers

    Which gut function is responsible for the movement of food through the GI tract?

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

    Which nervous system regulates local fluid and hormone release in the gut?

    <p>Submucosal plexus</p> Signup and view all the answers

    Which hormone is involved in the regulation of gut secretion and motility?

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

    What is the layer of the gut tract that regulates motility and muscle action?

    <p>Myenteric plexus</p> Signup and view all the answers

    Which type of gut control is responsible for the regulation of gut function through hormonal signals?

    <p>Intrinsic hormonal</p> Signup and view all the answers

    What is the main function of the salivary glands in the mouth?

    <p>To secrete amylase to break down starch into maltose and isomaltose</p> Signup and view all the answers

    What is the function of the rugae in the stomach?

    <p>To provide a wrinkly surface when the stomach is empty</p> Signup and view all the answers

    What is the function of the parietal cells in the stomach?

    <p>To produce HCL to maintain acidity and kill bacteria</p> Signup and view all the answers

    What is the function of the reticulum in the ruminant stomach?

    <p>To contract and slosh chyme between itself and the rumen</p> Signup and view all the answers

    What is the function of the omasum in the ruminant stomach?

    <p>To pump food into the abomasum</p> Signup and view all the answers

    What is the function of the liver in the alimentary system?

    <p>To produce and secrete bile</p> Signup and view all the answers

    What is the role of the gall bladder in the alimentary system?

    <p>To store and concentrate bile</p> Signup and view all the answers

    What is the function of the pancreas in the alimentary system?

    <p>To produce and secrete digestive enzymes</p> Signup and view all the answers

    What is the difference between the abomasum and the other chambers of the ruminant stomach?

    <p>The abomasum has a glandular epithelium and is highly acidic</p> Signup and view all the answers

    What is the function of the ruminoreticula groove?

    <p>To allow milk to bypass the rumen and enter the omasum</p> Signup and view all the answers

    What is the primary function of the mucosa in the stomach?

    <p>To secrete pepsinogen and HCL</p> Signup and view all the answers

    What is the function of the parietal cells in the stomach?

    <p>To secrete HCL and intrinsic factor</p> Signup and view all the answers

    What is the function of the rugae in the stomach?

    <p>To reduce the volume of the stomach when empty</p> Signup and view all the answers

    What is the function of the omasum in the ruminant stomach?

    <p>To pump food into the abomasum</p> Signup and view all the answers

    What is the function of the liver in the alimentary system?

    <p>To produce bile</p> Signup and view all the answers

    What is the role of the gall bladder in the alimentary system?

    <p>To store and concentrate bile</p> Signup and view all the answers

    What is the primary function of the pancreas in the alimentary system?

    <p>To produce most of the digestive enzymes</p> Signup and view all the answers

    What is the function of the rumen in the ruminant stomach?

    <p>To ferment food</p> Signup and view all the answers

    What is the function of the reticulum in the ruminant stomach?

    <p>To contract to slosh chyme between itself and the rumen</p> Signup and view all the answers

    What is the function of the salivary glands in the mouth?

    <p>To produce amylase</p> Signup and view all the answers

    Which hormone is released by stomach and pancreas to stimulate hunger?

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

    What is the primary function of the ventro medial area of the hypothalamus?

    <p>Regulation of satiety</p> Signup and view all the answers

    Which phase of digestion is characterized by the stimulation of acid and enzyme production and secretion?

    <p>Gastric phase</p> Signup and view all the answers

    What is the primary function of the enteric nervous system?

    <p>Regulation of gut motility</p> Signup and view all the answers

    Which hormone is involved in the regulation of gut secretion and motility?

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

    What is the primary function of the hormone secretin?

    <p>Stimulation of bile secretion</p> Signup and view all the answers

    Which hormone is involved in the regulation of gut motility and satiety?

    <p>Glucagon-like peptide-1</p> Signup and view all the answers

    What is the primary function of the hormone gastrin?

    <p>Stimulation of acid secretion</p> Signup and view all the answers

    Which hormone is involved in the regulation of gut secretion and motility in the small intestine?

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

    What is the primary function of the hormone motilin?

    <p>Stimulation of gut motility</p> Signup and view all the answers

    Which pancreatic enzyme is responsible for peptide chain digestion?

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

    What is the primary function of the submucosal plexus in the gut?

    <p>Regulates local fluid and hormone release</p> Signup and view all the answers

    Which hormone is involved in the regulation of gut secretion and motility in the duodenum?

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

    What is the primary function of the enteric nervous system in the gut?

    <p>Regulates gut motility and blood flow</p> Signup and view all the answers

    In which phase of digestion does the breakdown of disaccharides into monosaccharides occur?

    <p>Small intestine</p> Signup and view all the answers

    Which hormone is involved in the regulation of gut secretion and motility in the stomach?

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

    What is the primary function of the myenteric plexus in the gut?

    <p>Regulates motility and muscle action</p> Signup and view all the answers

    In which part of the gut does the absorption of salts and water occur?

    <p>Large intestine</p> Signup and view all the answers

    What is the primary function of the Brunner glands in the duodenum?

    <p>Secrete alkaline mucus</p> Signup and view all the answers

    Which hormone is involved in the regulation of gut motility and secretion in the small intestine?

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

    Study Notes

    Digestive Enzymes

    • Trypsin and carboxypeptidase are enzymes that digest proteins
    • Nucleic acid enzymes digest DNA and RNA
    • Pancreatic amylase is an enzyme that digests polysaccharides

    Small Intestine

    • Chemical digestion, absorption, and secretion occur in the small intestine
    • Pancreatic juice, bile, and interstitial juice are involved in chemical digestion
    • The small intestine is lined with microvilli, which increase the surface area for absorption
    • The mucosa of the small intestine is highly folded and lined with villi, which also increase the surface area for absorption

    Large Intestine

    • The large intestine consists of the caecum, ascending colon, transverse colon, descending colon, sigmoid colon, and rectum
    • The large intestine is involved in the fermentation of complex carbohydrates, absorption of salts and water, and excretion of faeces
    • Midgut fermentation occurs in the ascending colon, where commensal bacteria break down cellulose

    Gut Functions

    • Motility, secretion, digestion, absorption, and storage are the functions of the gut
    • The gut has intrinsic and extrinsic control mechanisms, including hormonal and neuronal regulation

    Gut Control

    • The enteric nervous system and hormones such as secretin, gastrin, CCK, GIP, and motilin regulate gut function
    • The vagus and splanchnic nerves also regulate gut function

    Gut Structure

    • The gut consists of four layers: mucosa, submucosa, tunica muscularis, and serosa/adventitia
    • The myenteric plexus and submucosal plexus are two types of nerve plexuses that regulate gut function

    Digestive Secretions and Motility

    • Parasympathetic stimulation increases digestive secretions and motility, while sympathetic stimulation decreases them
    • Hormonal signalling involves endocrine, neurocrine, paracrine, and autocrine signalling

    Phases of Digestion

    • The cephalic phase involves salivation, which is stimulated by parasympathetic innervation
    • The gastric phase involves acid and enzyme production and secretion, stimulated by gastrin and parasympathetic stimulation
    • The intestinal phase involves stimulation of motility and secretion, regulated by hormones such as secretin and CCK

    Hormones and Satiety

    • Ghrelin is the "hunger hormone", stimulated by an empty stomach and released by the stomach and pancreas
    • Leptin is the "satiety hormone", produced by adipocytes and opposing the action of ghrelin
    • Cholecystokinin, peptide YY, and GLP-1 are satiety hormones that stimulate hunger and satiety centres in the hypothalamus

    Layers of the Gut

    • Mucosa: site of absorption and secretion
    • Submucosa: contains blood vessels and lymphatic vessels
    • Tunica muscularis: layer of smooth muscle
    • Serosa/Adventitia: outermost layer

    Luminal Receptors

    • Mechanoreceptors: detect stretch and stimulate contractions
    • Chemoreceptors: sense chemical composition of the chyme and regulate pH
    • Osmoreceptors: sense osmolarity and control motility and secretion

    Hormonal Signaling

    • Endocrine: secretes into blood
    • Neurocrine: secreted by nerves
    • Paracrine: secreted by adjacent cells
    • Autocrine: secreted by self
    • Gut endocrine cells: columnar epithelial cells with narrow apex (sensory) and wide base (secretory)

    Phases of Digestion

    Cephalic Phase

    • Salivation, stimulated by parasympathetic innervation (cranial nerves)
    • Increased blood flow to glands
    • Brainstem regulates visual or olfactory salivation

    Gastric Phase

    • Acid and enzyme production and secretion
    • Sphincter is relaxed as well as stomach and duodenum to accommodate chyme
    • Stimulation of acid: Gastrin produced by duodenum, stomach, and pancreas
    • Increases acid, pepsinogen secretion

    Intestinal Phase

    • Stimulation of motility
    • Motilia: increased motility/peristalsis in the gut, 'clears' tract between meals
    • Cholecystokinin: decreases gastric emptying

    Hunger and Satiety

    • Hypothalamus: Ventro Medial area = "satiety centre", Lateral area = "appetite centre"
    • Low blood sugar sensory input appetite stimulated
    • Ghrelin: "hunger hormone", stimulated by empty stomach, released by stomach and pancreas, stimulates hunger
    • Leptin: "satiety hormone", opposes action of Ghrelin, produced by adipocytes, crosses blood-brain barrier to reach hypothalamus

    Satiety Hormones

    • Cholecystokinin, Peptide YY, Glucagon-like Peptide 1 (GLP-1)
    • GLP-1: secreted by gut cells and neurons, increases Insulin, decreases Glucagon, GI motility, gastric emptying, food and water intake

    Pancreatic Endocrine Cells

    • Islet of Langerhans: A cells (Glucagon), B cells (Insulin), D cells (Somatostatin)
    • A cells: secreted when blood glucose falls, triggers breakdown of glycogen into glucose in the liver
    • B cells: secreted when blood glucose is high, triggers storage of glucose in liver, skeletal muscle, and fat cells
    • D cells: secretion induced by low pH, suppresses release of hormone from A and B cells, inhibits gut motility and exocrine secretion

    Obesity

    • BMI over 25 = overweight
    • BMI over 30 = obese
    • BMI under 18.5 = underweight
    • Ideal BMI = 18.5-24.9
    • BMI = Weight (kg) / Height^2 (m)

    Drugs

    • Orlistat: inhibits pancreatic and gastric lipases, prevents around 1/3 of fat from food being absorbed
    • Semaglutide (diabetes medication): binds to and activates GLP-1 receptor

    Bariatric Surgery

    • Restrictive (Reduces stomach size and dietary intake)
    • Malabsorptive (bypassing the stomach and small intestine)
    • Gastric band: restrict amount you eat
    • Gastric bypass (Roux-en-Y): bypasses stomach and duodenum by attaching jejunum to gastric pouch so food is not absorbed at stomach

    Small Intestine

    • Chemical digestion: Pancreatic juice, Bile, and interstitial juice
    • Absorption: Proteins, Fats, and Carbohydrates
    • Duodenum: C-shaped, encircles pancreas, contains Brunner glands which secrete alkaline mucus
    • Jejunoileum: microvilli are lined with membrane-bound enzymes for final breakdown of nutrients for absorbable constituents

    Colon / Large Intestine

    • Food moves in this direction
    • Caecum, Ascending colon, Transverse colon, Descending colon, Sigmoid colon, Rectum

    Midgut Fermentation

    • Cellulose digestion by commensal bacteria in the ascending colon
    • Only in Grass eaters
    • Animals have simple single-chambered stomachs
    • Smooth mucosa (no villi)
    • Fermentation of complex carbohydrates
    • Absorption of salts + water
    • Excretion of faeces

    Rectum + Anus

    • Pelvic part of GI tract
    • Supports and stores faecal mass before defection
    • Build-up pressure against walls
    • Internal sphincter relaxes to open and allow faeces into canal
    • Relaxation of internal sphincter permits defecation

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    Description

    This quiz covers the enzymes involved in chemical digestion, such as trypsin and carboxypeptidase, and the process of absorption in the small intestine. It also explores the role of different juices and glands in the digestive process.

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