Bio 116 Exam 3 (Ch. 22 & 16)

*Which other systems work the digestive system to support the cells and tissues of the human body?*

·      Cardiovascular system

·      Respiratory system

·      Urinary system

*Starting at the mouth, identify the major organs of the digestive tract.*

·      Oral cavity (mouth)

·      Pharynx

·      Esophagus

·      Stomach

·      Small intestine

·      Large intestine

*List the accessory organs of the digestive tract.*

·      Teeth

·      Tongue

·      Salivary glands

·      Liver

·      Gallbladder

·      Pancreas

*What is the importance of mesenteries?*

·      Areolar tissue lies between mesothelial layers (Provides access route for blood vessels, nerves, and lymphatics)

·      Stabilizes attached organs.

·      Prevents entanglement of intestines

*Name the four layers of the digestive tract beginning from the lumen of the digestive tract.*

·      Mucosa (inner lining)

·      Submucosa

·      Muscular layer

·      Serosa

*Compare the submucosal neural plexus with the myenteric plexus.*

·      Submucosal neural plexus: Located in the submucosal layer. Innervates the mucosa and submucosa. Contains sensory neurons and autonomic nerve fibers.

·      Myenteric plexus: Network of sensory neurons and autonomic nerve fibers. Located in the muscularis externa between the circular and longitudinal layers. Works with the submucosal plexus to coordinate local control of digestive activity.

*Describe the orientation of smooth muscle fibers in the muscular layer of the digestive tract.*

·      The cells are aligned parallel to one another. Usually, an inner circular layer and other longitudinal layer.

*Identify the structural characteristics of smooth muscle fibers.*

·      Contain actin and myosin filaments.

·      Contain no T tubules.

·      Sarcoplasmic reticulum forms loose network throughout the sarcoplasm.

·      Have no myofibrils or sarcomeres.

*Why can smooth muscle contract over a wider range of resting lengths than skeletal muscle?*

·      The thick and thin filaments are scattered and not organized into sarcomeres.

*Which is more efficient in propelling intestinal contents along the digestive tract: peristalsis or segmentation. Why?*

·      Peristalsis because the bolus remains together and goes more quickly.

*Cite the major mechanisms that regulate and control digestive activities.*

·      Local factors

·      Neural control mechanisms

·      Hormonal control mechanisms

*Describe enteroendocrine cells.*

·      Endocrine cells in the epithelium of the digestive tract.

*Define ingestion.*

·      Occurs when solid food and liquid enter the oral cavity.

*Distinguish between chemical digestion and absorption.*

·      Chemical digestions: Chemical and enzymatic breakdown of food into small organic molecules that can be absorbed by the digestive epithelium.

·      Absorption: Movement of nutrients across the digestive epithelium and into the bloodstream.

*Describe the function of the large intestine.*

·      Dehydration and compaction of indigestible materials.

*The oral cavity is lined by which type of epithelium?*

·      Oral mucosa (stratified squamous epithelium)

*Name the structures that forms the roof of the mouth.*

·      Hard palate: formed by the palatine processes of the maxillary bones and horizontal plates of the palatine bones.

·      Soft palate: Muscular region posterior to the hard palate

*Describe the location of the fauces.*

·      Space between oral cavity and oropharynx

*What effects might a shortened frenulum of the tongue cause?*

·      Ankyloglossia (tongue-tie)

*Name the three main parts of a typical tooth.*

·      Crown

·      Neck

·      Root

*What is the name sometimes given to the third set of molars?*

·      Wisdom teeth

*Name the regions and functions of the pharynx.*

·      Nasopharynx

·      Oropharynx

·      Laryngopharynx

Functions: Common passageway for solid food, liquids, and air. Key role in swallowing

*Describe the muscular layer of the esophagus.*

·      Inner circular and outer longitudinal layers; superior third is skeletal muscle, middle third is mixed skeletal and smooth muscle, inferior third is smooth muscle.

*Describe the major event in each of the three phases of swallowing.*

·      Buccal Phase: Voluntary; Food is formed into a bolus and forced into the oropharynx, closing off the nasopharynx.

·      Pharyngeal Phase: Automatic; Bolus contacts the palatal arches and moves into the esophagus, as pharyngeal constrictors force the bolus through the pharynx, past the closed glottis and into the esophagus.

·      Esophageal Phase: Automatic; Swallowing begins as pharyngeal muscles contract and bolus is moved towards the stomach through the esophagus by peristaltic waves.

*What is the falciform ligament?*

·      A remnant of the ventral mesentery that connects the liver to the anterior body wall of the peritoneal cavity.

*What is the function of the lesser omentum?*

·      Provides an access route for blood vessels and other structures entering/leaving the liver.

*Explain the significance of peritoneal fluid.*

·      Thin layer that separates parietal and visceral surfaces. Allows sliding movements without friction or irritation.

*Name the four major regions of the stomach in order from its junction with the esophagus to the small intestine.*

·      Fundus

·      Cardia

·      Body

·      Pylorus

*What anatomical feature of the stomach allows the organ to form chyme?*

Oblique layer of the muscularis externa

*Describe the lining of the stomach.*

·      Rugae: prominent but temporary mucosal folds that allow the stomach to expand; can flatten out until they almost disappear at maximal distention of the stomach.

*Explain the significance of the alkaline mucous layer lining the interior surface of the stomach.*

·      Protects epithelial cells against acid and enzymes in gastric lumen.

*What is the function of parietal cells?*

·      Secrete intrinsic factor and hydrochloric acid (HCl).

*Describe the alkaline tide.*

·      Sudden influx of bicarbonate ions into the bloodstream.

*Name the layers of the small intestine from superficial to deep.*

·      Mucosa

·      Submucosa

·      Muscular layer

·      Serosa

*Describe the anatomy of the intestinal mucosa.*

·      Has transverse folds called circular folds bearing small projections called villi. These folds and projections increase the surface area available for absorption. Each villi contains a terminal lymphatic capillary called a lacteal. Between the bases of the villi are intestinal glands lined by enteroendocrine, mucous, and stem cells.

*Explain the function of lacteals.*

·      Transports materials that cannot enter blood capillaries.

*Name the three segments of the small intestine from proximal to distal.*

·      Duodenum

·      Jejunum

·      Ileum

*Identify the segment of the small intestine found within the epigastric region.*

·      Duodenum

*What is the primary function of the duodenum?*

·      “Mixing Bowl”; Receives chyme from stomach and digestive secretions from liver, gallbladder, and pancreas.

*A traumatic injury to the umbilical region could affect which segments of the small intestine?*

·      Jejunum & Ileum

*Name the major hormones that regulate digestive activities.*

·      Gastrin

·      Gastric Inhibitory Peptide (GIP)

·      Secretin

·      Cholecystokinin (CCK)

·      Vasoactive Intestinal Peptide (VIP)

·      Enterocrinin

*How would the ph of the intestinal contents be affected if the small intestine did not produce secretion?*

·      The pH of the intestinal contents would be lower (more acidic) than normal because secretin stimulates the pancreas to release a fluid high in chyme entering the duodenum from the stomach.

*Does a high fat meal raise or lower the level of CCK in the blood?*

·      High-fat meal raises the CCK level in blood.

*Name and briefly describe an important characteristic of each of the three phases of gastric secretion.*

·      Cephalic phase: Begins when you see, smell, taste, or think of food.

·      Gastric phase: Begins with stimuli as food arrives in the stomach. Gastrin secretion.

·      Intestinal phase: Begins when chyme enters duodenum.

*Describe two central reflexes triggered by the stimulation of the stretch receptors in the stomach wall.*

·      Gastroenteric reflex: stimulates motility and secretion along the entire small intestine.

·      Gastrolienal reflex: triggers the opening of the ileocecal valve, allowing materials to pass from the small intestine into the large intestine.

*Why might severing the branches of the vagus nerves that supply the stomach provide relief for a person who is suffering from chronic gastric ulcers?*

·      It would interrupt parasympathetic stimulation of gastric secretions and the consequent reduction in acid secretions would provide some relief.

*Name the major functions of the large intestine.*

·      Reabsorbing water and compacting intestinal contents into feces.

·      Absorbing important vitamins generated by bacterial action.

·      Storing fecal material prior to defecation.

*Identify the four regions of the colon.*

·      Ascending colon

·      Transverse colon

·      Descending colon

·      Sigmoid colon

*Describe mass movements.*

·      Powerful peristaltic contractions. Occur a few times each day in response to distention of the stomach and duodenum. Begin at the transverse colon and push materials along the distal portion of the large intestine.

*How does digestion occur in the large intestine?*

·      The mucosa of the large intestine does not produce digestive enzymes. Digestion that does occur in the large intestine results from enzymes secreted into the small intestine or from bacterial action.

*Define hemorrhoids.*

·      Distended (swollen) veins in the distal portion of the rectum that may result from pregnancy or straining during defecation.

*Describe the two positive feedback loops involved in the defecation process.*

·      Long reflex: coordinated by sacral parasympathetic system. Stimulates mass movements that push feces toward the rectum from the descending colon and sigmoid colon.

·      Short reflex: stimulates the myenteric plexus in the sigmoid colon and rectum.

*What is the function of salivary glands?*

·      Produce saliva containing mucins and enzymes.

*Distinguish between the exocrine and endocrine secretions of the pancreas.*

·      Exocrine cells secrete buffers and digestive enzymes.

·      Endocrine cells secrete several hormones.

*Which accessory organ of the digestive system is responsible for almost 200 known functions.*

·      Liver

*Name the three pairs of salivary glands.*

·      Sublingual salivary glands

·      Submandibular salivary glands

·      Parotid salivary glands

*Damage to the parotid glands would affect the digestion of which nutrient?*

·      The enzyme, Amylase, which breaks down complex carbohydrates.

*Which pair of salivary glands contributes most to saliva production?*

·      Submandibular salivary glands (70%)

*Which pair of salivary glands secretes substances that reduce oral bacteria populations?*

·      Submandibular salivary glands

*Describe the outer covering of the liver.*

·      It is covered by a layer of visceral peritoneum and wrapped in a tough fibrous capsule.

*What structure marks the division between the left lobe and right lobe of the liver?*

·      Falciform ligament

*Name the lobes of the liver.*

·      Left lobe

·      Right lobe

·      Caudate lobe

·      Quadrate lobe

*What is the function of the gallbladder?*

·      Temporarily stores bile produced by the liver.

*Define hepatocyte.*

·      Liver cells

*Describe a portal triad.*

·      Contains three structures: 1. A branch of the hepatic portal vein (receives blood from the hepatic portal system bringing blood from abdominal viscera) 2. A branch of the hepatic artery proper 3. A bile duct.

·      Branches from the arteries and veins of each portal area deliver blood to liver (hepatic) sinusoids of adjacent liver lobules.

*Define stellate macrophages and indictate their functions.*

·      Liver macrophages (Kupffer cells)

·      Function: engulf pathogens, cell debris, and damaged blood cells

*Define emulsification.*

·      Bile salts break lipid droplets apart

*Trace a drop of bile from the hepatic ducts to the duodenal lumen.*

·      Hepatic ducts

·      Common hepatic duct

·      Bile duct

·      Duodenal ampulla/papilla

·      Duodenal lumen

*What is the primary digestive function of the pancreas?*

·      Produces pancreatic juice that contains buffers and several digestive enzymes necessary for the breakdown of starches, lipids, nucleic acids, and proteins.

*Describe hepatitis.*

·      Inflammation of the liver

*Describe cholecystitis.*

·      Irritation and damage to the gallbladder wall caused by gallstones too large to pass.

*What bacterium is responsible for most peptic ulcers?*

·      Helicobacter pylori

*What is the common goal of the nervous and endocrine systems?*

·      Common goal of both is to preserve homeostasis by coordinating and regulating other cells, tissues, organs, and systems.

*Describe the structural classification of hormones.*

·      Amino acid derivatives (Thyroid hormones, catecholamines, tryptophan derivates)

·      Peptide hormones

·      Lipid derivatives (Eicosanoids, steroid hormones)

Identify the organs and tissues of the endocrine system and the key functions of the hormones they secrete.

·      Hypothalamus: fluid balance, smooth muscle contraction, control of hormones secreted by anterior pituitary gland.

·      Pituitary Gland: regulate adrenal glands (cortex), thyroid gland, reproductive organs, melanin production.

·      Thyroid Gland: metabolic rate and calcium ion levels in body fluids.

·      Adrenal Glands: mineral balance, metabolic control, resistance to stress; also release norepinephrine and epinephrine during synaptic activation.

·      Pancreas (Pancreatic Islets): rate of glucose uptake and utilization by tissues.

·      Pineal Gland: melatonin (reproductive function and sleep rhythms).

·      Parathyroid Glands: calcium ion levels in body fluids.

\
\
·      Heart: regulates blood volume

·      Thymus: stimulates and coordinates immune response

·      Digestive Tract: coordinating system functions, glucose metabolism, and appetite.

·      Kidneys: regulate RBC production, calcium/phosphate absorption in GI tract, blood volume

·      Gonads: affect growth, metabolism, sexual characteristics; coordinate reproductive organ activities.

*Differentiate between a first and second messenger.*

·      First messenger: hormone binds to protein receptor in the membrane (extracellular signal; hormone)

·      Second messenger: ion or water-soluble object that moves around cell by diffusion. (produced inside the cell)

*Define hormone receptor.*

·      Hormones must affect target cells by interacting with a specific receptor.

*Which type of hormone diffuses across the plasma membrane and binds to receptors in the cytoplasm?*

·      Steroid hormones

*Define regulatory hormone.*

·      Controls the secretory activities of endocrine cells in the anterior lobe of the pituitary gland. These hormones can be releasing hormones or inhibiting hormones.

*Identify the three mechanisms by which the hypothalamus integrates neural and endocrine function.*

·      Hypothalamic neurons synthesize two hormones (ADH & OXT)

·      The hypothalamus secretes regulatory hormones.

·      The hypothalamus contains autonomic centers that exert direct neural control over the endocrine cells of the adrenal medulla.

*Name and describe the characteristics and functions of the blood vessels that link the hypothalamus with the anterior lobe of the pituitary gland.*

·      Hypophyseal portal system links the hypothalamus with the anterior lobe.

·      Fenestrated capillary beds in each structure are connected by portal vessels. This arrangement ensures that hypothalamic regulatory hormones reach the “downstream” endocrine cells of the anterior lobe directly, before mixing with, and being diluted by, the general circulation.

*Identify 9 pituitary hormones and their target tissues.*

·      Thyroid-stimulating hormone (TSH): thyroid gland

·      Adrenocorticotropic hormone (ACTH): adrenal gland

·      Follicle-stimulating hormone (FSH): ovary

·      Luteinizing hormone (LH): testis

·      Growth hormone (GH): Musculoskeletal system

·      Prolactin (PRL): Mammary gland

·      Melanocyte-stimulating hormone (MSH): skin

·      Antidiuretic hormone (ADH): kidneys

·      Oxytocin (OXT): uterus

*In a dehydrated person, how would the amount of ADH released by the posterior lobe of the pituitary change?*

·      The amount of ADH released increases in response to increased blood osmotic pressure resulting from a rise in solute concentration.

*List the hypothalamic releasing hormones.*

·      Corticotropin-releasing hormone (CRH)

·      Thyrotropin-releasing hormone (TRH)

·      Growth hormone-releasing hormone (GH-RH)

·      Growth hormone-inhibiting hormone (GH-IH)

·      Prolactin-releasing hormone (PRH)

·      Prolactin-inhibiting hormone (PIH)

·      Gonadotropin-releasing hormone (GnRH)

*The release of which pituitary hormone would lead to an increased level of somatomedins in the blood?*

·      Growth hormone (hypothalamic hormones)

*What effects would increased circulating levels of glucocorticoids have on the pituitary secretion of ACTH?*

·      They would inhibit the release of CRH which would reduce the secretion of ACTH.

*Name the hormones of the thyroid gland.*

·      T4: Thyroxine

·      T3: Triiodothyronine

*Why do signs and symptoms of thyroxine concentration not appear until about a week after a thyroidectomy (surgical removal of the thyroid gland)?*

·      Most of the body’s reserves of the thyroid hormone, thyroxine (T4), are bound to transport protein in the bloodstream called thyroid binding globulins. Because these compounds represent such a large reserve of thyroxine, it takes several days after removal of the thyroid gland for blood levels of thyroxine to decrease.

*Explain how the parathyroid hormone increases blood calcium levels.*

·      Decreases calcium deposition in bones, by increasing reabsorption of calcium from the blood by the kidney, and by increasing the production of calcitriol by the kidneys.

*Decreased blood calcium levels would result in increased secretion of what hormone?*

·      PTH

*Name the regions and zones of an adrenal gland from superficial to deep.*

·      Zona glomerulosa

·      Zona fasciculata

·      Zona reticularis

*Cite the hormones secreted by each region of the adrenal gland.*

·      Adrenal medulla: secretes epinephrine and norepinephrine

·      Adrenal cortex: secretes mineralocorticoids, primarily aldosterone, glucocorticoids, mainly cortisol (or hydrocortisone) and corticosterone, and androgens.

*What effect would increased cortisol levels on blood glucose levels?*

·      Because cortisol decreases the use of glucose by cells while increasing both the available glucose (by promoting the breakdown of glycogen) and the conversion rate of amino acids to carbohydrates

*Identify the types of cells in the pancreatic islets and the hormones produced by each.*

·      Alpha cells: glucagon

·      Beta cells: insulin

·      Delta cells: peptide hormone identical to growth hormone-inhibiting hormone (GH-IH)

·      Pancreatic polypeptide cells (PP cells): pancreatic polypeptide (PP)

*The secretion of which hormone lowers blood glucose concentrations?*

·      insulin

*What is the effect of increased glucagon levels on the amount of glycogen stored in the liver?*

·      Stimulate the conversion of glycogen to glucose in liver, which in turn decreases the amount of glycogen stored in the liver

*Identify the hormone-secreting cells of the pineal gland.*

·      pinacocytes

*Increased amounts of light would inhibit the production of which hormone?*

·      melatonin

*List three functions suggested for melatonin in humans.*

·      Setting circadian rhythms.

·      Inhibiting reproductive functions.

·      Protecting against damage by free radicals.

*Describe the two types of diabetes mellitus.*

·      Type 1 diabetes: inadequate insulin production from pancreatic beta cells. Must receive insulin daily and develops in children and young adults.

·      Type 2 diabetes: Most common form. Body produces normal amounts of insulin but tissues do not respond properly. Associated with obesity.

\