Digestive System - Lecture 6
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What is the primary function of the digestive system?

  • To provide energy through fermentation
  • To break down complex nutrients for absorption (correct)
  • To store waste until elimination
  • To produce hormones for metabolic regulation

    • Which stage of digestion involves the actual breakdown of food into smaller molecules?

  • Secretion
  • Mastication
  • Chemical digestion (correct)
  • Motility

    • What are the two main components of the digestive system?

  • Gastrointestinal tract and immune system
  • Salivary glands and respiratory tract
  • Alimentary canal and accessory organs (correct)
  • Alimentary canal and endocrine system

    • Which part of the oral cavity is described as the space outside the teeth and gums?

    <p>Vestibule of the mouth</p> Signup and view all the answers

    How many teeth does an individual develop during childhood?

    <p>20 primary teeth</p> Signup and view all the answers

    What are the three main parts of a tooth?

    <p>Crown, neck, and root</p> Signup and view all the answers

    What is one of the primary functions of the tongue?

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

    How many permanent teeth does an individual typically develop?

    <p>32</p> Signup and view all the answers

    What is the primary function of the teeth?

    <p>Chewing or mastication of food</p> Signup and view all the answers

    Which layer of a tooth is responsible for binding the roots to the gums and jawbone?

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

    What term describes the semi-digested food found in the stomach?

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

    Which part of the pharynx is located behind the nasal cavity?

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

    What is the role of pulp in a tooth?

    <p>Contains blood vessels and nerves</p> Signup and view all the answers

    What anatomical structure separates the papillary and tonsillar areas on the tongue?

    <p>Sulcus terminalis</p> Signup and view all the answers

    What is the average capacity of an empty stomach?

    <p>50 ml</p> Signup and view all the answers

    What is the main function of saliva production?

    <p>Facilitating digestion and lubrication</p> Signup and view all the answers

    What is the primary composition of saliva?

    <p>99.4% water and ions</p> Signup and view all the answers

    Which of the following glands produces the majority of saliva?

    <p>Submandibular glands</p> Signup and view all the answers

    What is the function of the muscularis externa layer in the gastrointestinal tract?

    <p>To generate and coordinate contractions</p> Signup and view all the answers

    How many liters of saliva are produced by the salivary glands each day?

    <p>1 to 1.5 liters</p> Signup and view all the answers

    What percentage of saliva is produced by the parotid salivary glands?

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

    Which layer of the gastrointestinal tract wall is responsible for absorption?

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

    What structure covers the outer surface of the digestive tract within the abdominal cavity?

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

    What are the three components of the mucosa layer?

    <p>Epithelial layer, lamina propria, muscularis mucosae</p> Signup and view all the answers

    What is the primary function of the pyloric sphincter?

    <p>To allow partially digested food to pass into the duodenum</p> Signup and view all the answers

    Which type of cell in the stomach mucosa is responsible for producing hydrochloric acid?

    <p>Parietal cells</p> Signup and view all the answers

    What is the approximate length of the small intestine?

    <p>6 m</p> Signup and view all the answers

    Which section of the small intestine is primarily involved in nutrient absorption, particularly sugars and fatty acids?

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

    What is the diameter of the large intestine?

    <p>6.3 cm</p> Signup and view all the answers

    Which part of the large intestine primarily serves as a receptacle for incoming liquid waste?

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

    What is one proposed function of the appendix?

    <p>Storage area for beneficial bacteria</p> Signup and view all the answers

    What is the weight and approximate location of the liver in the body?

    <p>1.5 kg, upper right and center abdomen</p> Signup and view all the answers

    What are the structural units of the liver called?

    <p>Liver lobules</p> Signup and view all the answers

    From which two sources do sinusoids in liver lobules receive blood?

    <p>Hepatic artery and portal vein</p> Signup and view all the answers

    What do the central veins of liver lobules unite to form?

    <p>Hepatic veins</p> Signup and view all the answers

    What is the pH level of gastric juice in the stomach?

    <p>1 to 2</p> Signup and view all the answers

    What role do the rugae of the stomach lining serve?

    <p>Facilitate expansion without tearing</p> Signup and view all the answers

    What is the primary function of the ileocecal valve?

    <p>Prevent reflux of large intestine contents</p> Signup and view all the answers

    The major histological components of the liver include which of the following?

    <p>Stroma and parenchyma</p> Signup and view all the answers

    How many parts is the colon divided into?

    <p>Four parts</p> Signup and view all the answers

    Study Notes

    Digestive System - Lecture 6

    • Digestive system function: Breaks down complex organic nutrients into simpler organic/inorganic molecules. These absorb into blood/lymph and are transported to cells.

    Stages of Digestion

    • Ingestion: Taking food and liquid into the oral cavity.
    • Mastication (Chewing): Breaks down solid food into digestible pieces.
    • Motility: Muscular movements of materials through the digestive tract.
    • Secretion: Release of lubricating/protective mucus, digestive enzymes, acids, alkaline fluids, and bile.
    • Hormone release: Controls motility and secretion locally.

    Chemical Digestion & Absorption

    • Chemical digestion: Enzymatic breakdown of large molecules to smaller ones.
    • Absorption: Uptake of small molecules and water into the blood and lymph.

    Two Main Parts of the Digestive System

    • Alimentary canal (GIT): Mouth to anus; includes oral cavity, pharynx, esophagus, stomach, small intestine, and large intestine.
    • Accessory organs: Salivary glands, liver, gallbladder, and pancreas.

    Oral Cavity Parts

    • Vestibule: Space outside the teeth and gums.
    • Mouth cavity proper: Surrounded by teeth, gums, hard and soft palates, and tonsils.

    Tooth Anatomy

    • Crown: Visible part of the tooth.
    • Neck: Between crown and root.
    • Root: Extends into bone, holding the tooth in place.

    Deciduous Teeth

    • Individuals develop a set of 20 deciduous teeth.
    • Erupt around 6 months of age.
    • Typically complete by 2 years of age.

    Permanent Teeth

    • Individuals develop 32 permanent teeth.
    • Includes incisors, canines, premolars, and molars.

    Tongue Functions

    • Chewing, speech, taste, and swallowing.

    Tongue Surfaces

    • Ventral (lower) surface: Smooth.
    • Dorsal surface: Irregular, with papillae and lingual tonsils.

    Saliva Production

    • Salivary glands produce 1-1.5 liters of saliva daily.

    Saliva Composition

    • 99.4% water, plus ions and enzymes.

    Salivary Glands

    • Types: Minor (in oral mucosa, 10%), and major (parotid, submandibular, sublingual).
    • Locations: Parotid (below and in front of ears), submandibular (posterior mandible corners), sublingual (below the mouth floor).

    Percentage of Saliva Origin

    • Approximately 70% from submandibular glands.
    • 25% from parotid glands.
    • 5% from sublingual glands.

    Gastrointestinal Tract Wall Layers

    • Mucosa: Inner layer.
    • Submucosa: Layer beneath mucosa.
    • Muscularis externa: Muscle layer (circular and longitudinal).
    • Serosa: Outermost layer.

    Mucosa Layer Components

    • Epithelial layer
    • Lamina propria: Connective tissue.
    • Muscularis mucosae: Thin layer of smooth muscle.

    Muscularis Externa Function

    • Responsible for mixing and propelling luminal contents forward.
    • Composed of circular and longitudinal layers of smooth muscle.

    Enteric Nervous System Function

    • Located in the muscularis externa and submucosa.
    • Generates and coordinates muscular contractions.

    Serosa Layer Purpose

    • Thin sheet of loose connective tissue.
    • Rich in blood vessels, lymphatics, and adipose tissue.
    • Covers the digestive tract in the abdominal cavity.

    Pharynx Length

    • Approximately 5 inches long.

    Pharynx Division

    • Nasopharynx, oropharynx, and laryngopharynx.

    Pharynx Function

    • Allows passage of air and food. Does not have a digestive function.

    Enamel Layer Purpose

    • Hardest, white outer part of the tooth.
    • Protects underlying layers.

    Dentin Layer Function

    • Layer of hard tissue beneath enamel.
    • Provides additional support and protection.

    Pulp Role

    • Soft, living inner structure of the tooth.
    • Contains blood vessels and nerves.

    Cementum Layer Function

    • Connective tissue layer.
    • Attaches tooth roots to gums and jawbone.

    Primary Teeth Function

    • Chewing (mastication).

    Sulcus Terminalis Function

    • V-shaped groove separating papillary and tonsillar areas on the tongue's dorsal surface.

    Major Salivary Gland Ducts

    • Each major salivary gland has at least one duct that takes saliva to the oral cavity.

    Saliva Production Purpose

    • Digestive, lubricating, and protective functions in the mouth.

    Stomach - Pt2

    • Function: Temporary storage, mechanical digestion (muscular contractions), and chemical digestion (acid and enzymes).
    • Empty size: Approximately 50 ml.
    • Stomach lining folds: Rugae.
    • Semi-digested food: Chyme.
    • Major regions: Cardia, fundus, body, and pylorus.

    Cardiac Sphincter

    • Located at the esophagus-stomach junction.
    • Prevents stomach acid from reflux.

    Pyloric Sphincter

    • Opens to allow partially digested food (chyme) into the duodenum.

    Stomach Mucosa Cells

    • Mucous cells, chief cells, parietal cells, and enteroendocrine G cells.

    Parietal Cells Function

    • Hydrochloric acid (HCl) and intrinsic factor production (for vitamin B12 absorption).

    Small Intestine Length

    • Approximately 6 meters long.

    Small Intestine Segments

    • Duodenum, jejunum, and ileum.

    Duodenum Function

    • Breaks down food and absorbs nutrients.
    • Allows food to pass from stomach into the small intestine.

    Jejunum Function

    • Absorbs sugars, fatty acids, and amino acids.

    Ileum Function

    • Absorbs vitamin B12 and reabsorbs conjugated bile salts.

    Large Intestine Diameter/Length

    • Approximately 6.3 cm in diameter and 1.5 m in length

    Large Intestine Parts

    • Colon, cecum, rectum, and anus.

    Cecum Function

    • Receptacle for liquids entering the large intestine.
    • Absorbs salts, electrolytes; involved in lubrication/cellulose digestion.

    Appendix Function

    • Function unknown, one hypothesis is storage area for beneficial bacteria.

    Rectum Length/Diameter

    • Approximately 8 inches (20 cm) in length and 2.5 inches in diameter.

    Liver Weight/Location

    • 1.5 kg or 2% of total body weight.
    • Upper right/center of the abdominal cavity, below the diaphragm.

    Liver Lobes

    • Two large lobes: right and left.

    Liver Structural Units

    • Liver lobules.

    Sinusoids in Liver Lobules

    • Receive blood from hepatic artery and portal vein.

    Central Veins in Liver Lobules

    • Unite to form hepatic veins, which take blood out the liver to the inferior vena cava.

    Major Histological Components of Liver

    • Stroma (capsule of Glisson) and parenchyma (hepatocytes).

    Cardiac Sphincter Function

    • Allows food to pass from the esophagus to the stomach.
    • Prevents stomach acid from refluxing into the esophagus.

    Stomach Size Change After Meal

    • Can enlarge to up to 1.5 liters.

    Rugae Function

    • Flatten as the stomach fills, allowing the lining to expand without tearing.

    Gastric Juice pH

    • pH of 1 to 2.

    G Cells Function

    • Secrete gastrin, stimulating greater gastric juice secretion.

    Small Intestine Location

    • Extends from the stomach to the cecum of the large intestine.

    Ileocecal Valve Function

    • Prevents large intestine contents from refluxing into the ileum during peristalsis (muscle contractions).

    Haustra in Colon

    • Sacs in the colon wall. Produce the segmented appearance of the colon.
    • Formed by the teniae coli (3 longitudinal ribbons of smooth muscle).

    Colon Divisions

    • Ascending colon, transverse colon, descending colon, and sigmoid colon.

    Liver's Relation to Hepatic Artery/Portal Vein

    • Blood is received from hepatic artery and portal vein.

    Capsule of Glisson Function

    • Part of the liver's stroma (supporting tissue). Consists of connective tissue and contains blood vessels

    Hepatocytes Function

    • Functional units of the liver. Responsible for metabolic processes.

    Hepatic Vein Destination

    • Takes blood out of the liver to the inferior vena cava.

    Capsule of Glisson Covering

    • Covered by a layer of mesothelium.

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    Digestive System Questions Lecture 6 PDF

    Description

    Explore the intricate functions and stages of the digestive system in this comprehensive quiz. From ingestion to absorption, learn how complex nutrients are converted into simpler forms that our body can utilize. Test your knowledge on the chemical processes and the anatomy involved in digestion.

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