Anatomy 2

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Anatomy 2
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  1. Respiratory System
    • An organ system that rhythmically takes in air and expels it from the body
    • Supplying the bodyw ith oxygen and expelling carbon dioxide that it generates
  2. Primary Organs of Respiratory System
    • Nose
    • Pharnynx
    • Larynx
    • Trachea
    • Bronchi
    • Lungs
  3. Upper-Respiratory Tract
    • The airway from the nose through the larynx
    • Organs in the head and neck
  4. Lower-Respiratory Tract
    The airway from the trachea through the lungs
  5. Nose
    Warms, cleanses, and humidifies inhaled air, detects odors, and serves as a resonating chamber that amplifies the voice
  6. Inferior Nose
    • Supported by the lateral and alar cartilages
    • -Forms the flared portions
  7. Nasal Cavity
    Divided into right and left halves called nasal fossae
  8. Nasal Septum
    • The dividing wall
    • Composed of bone and hyaline cartilage
    • Vomer forms inferior part
    • Septal cartilage forms the anterior part
  9. Palate
    • Separates the nasal cavity from the oral cavity
    • Allows you to breathe while chewing food
  10. Vestibule
    • Lined with stratified squamous epithelium
    • Stiff guard hairs that block insects and debris from entering the nose
  11. Olfactory Epithelium
    • Covers a small area of the roof of the nasal fossa and adjacent parts of the septum and superior concha
    • Odors are detected by these sensory cells
    • Ciliated pseudostratified columnar epithelia
    • -Cilia are immobile and serve to bind odor molecules
  12. *******Respiratory Epithelium
    • Covers the rest of the nasal cavity, except vestibule
    • Ciliated pseudostratified columnar epithelia
    • -Cilia is mobile, propels mucus toward pharynx
    • Goblet cells secrete mucus
  13. ******Nasal Mucosa
    • Contains mucous glands
    • Supplement the mucus produced by the goblet cells
    • Inhaled dust, pollen, bacteria, and other foreign matter stick to the mucus and are swallowed
  14. Lamina Propria
    • Well populated by lymphocytes and plasma cells that mount immune defenses against inhaled pathogens
    • Contains large blood vessels that help warm the air
  15. Inferior Concha
    • Has a venous plexus called the erectile tissue
    • Every 30-60 minutes, the tissue on one side swells with blood and restricts airflow through that fossa
    • Air is directed through the other fossa, allowing the engorged side time to recover from drying
  16. Pharynx
    • A muscular funnel from the choanae to the larynx
    • Nasopharynx
    • Oropharynx
    • Laryngopharynx
  17. Nasopharynx
    • Receives the auditory tubes from the middle ears and hosues the paryngeal tonsil
    • Inhaled air turns 90° downward as it passes through
    • Large particles cannot make the turn because of inertia
    • -They collide with the posterior wall and stick to the mucosa near the tonsil
    • Passes only air
    • Lined by pseudostratified columnar epithelium
  18. Oropharynx
    • A space between the posterior margin of the soft palate and the epiglottis
    • Passes air, food, and drink
    • Lined by stratified squamous epithelium
  19. Laryngopharynx
    • Esophagus begins at this point
    • Passes air, food, and drink
    • Lined by stratified squamous epithelium
  20. Larynx
    • Keeps food and drink out of the airway
    • Evolved the additional role of sound production in many animals
    • Superior opening is guarded by the epiglottis
    • Has vestibular folds
    • Does not produce speech
    • -Words are formed by the pharynx, oral cavity, tongue, and lips
  21. ******Epiglottis
    • At rest, it stands almost vertically
    • During swallowing, extrinsic muscles of larynx pull larynx up towards it
    • Tongue pushes it down to meet larynx
    • Closes the airway and directs food and drink into the esophagus
    • Does not help in forming speech
  22. Extrinsic Muscles of Larynx
    Connect it to the hyoid bone and elevate it during swallowing
  23. Intrinsic Muscles of Larynx
    • Control the vocal cords by pulling on the corniculate and arytenoid cartilages, causing the cartilages to pivot
    • Air forced between the adducted vocal cords vibrates them, producing a high-pitched sound
  24. Males Larynx
    • Longer and thicker
    • Vibrate more slowly
    • Produce lower-pitched sounds
  25. Trachea
    • Supported by 16-20 C-shaped rings of hyaline cartilage
    • -Keep it from collapsing when you inhale
    • -Gap allows room for the esophagus to expand as food passes by
    • Trachealis muscles contract or relax to adjust airflow
    • Pseudostratified columnar epithelium composed of mucus secreting goblet cells, ciliated cells, and short basal stem cells
  26. Mucociliary Escalator
    • Mucus traps inhaled particles
    • Upward beating of cilia drives the debris-laden mucus towards the pharynx
    • Swallowed
  27. Adventitia
    • Outermost layer of trachea
    • Fibrous connective tissue
  28. Carina
    Directs the airflow to the right and left bronchi
  29. Hilum
    • Slit through which the lung receives the main bronchus, blood vessels, lymphatics, and nerves
    • These structures constitute the root of the lung
  30. Left Lung
    • Has a superior and inferior lobe
    • Single oblique fissure
  31. Right Lung
    • Has a superior, middle, and inferior lobe
    • Horizontal fissure that separates the superior and middle lobes
    • Oblique fissure separates the middle and inferior lobes
  32. Right Main Bronchus
    • Inhaled foreign objects lodge here more often
    • Gives off three branchs
    • -Superior, middle, and inferior lobar bronchi
    • -One to each lobe of right lung
  33. Left Main Bronchus
    Gives off superior and inferior lobar bronchi to the two lobes of the left lung
  34. Lobar Bronchi
    • Branch into segmental bronchi
    • -10 in the right and 8 in the left
    • -Each ventilates a functionally independent unit of lung tissue called a broncopulmonary segment
    • Supported by overlapping crescent-shaped cartilaginous plates
  35. Main Bronchi
    • Supported by C-shaped rings of hyaline cartilage
    • Lined with ciliated pseudostratified columnar epithelium
  36. Bronchial Tree
    • Has a lot of elastic connective tissue
    • -Contributes to the recoil that expels air from the lungs in each respiratory cycle
    • Branches of the pulmonary artery follow it on their way to the alveoli
  37. Bronchioles
    • Continuations of the airway that lack supportive cartilage
    • Portion of the lung ventilated by one is called a pulmonary lobule
    • Have ciliated cuboidal epithelium
    • Well-developed layer of smooth muscle
    • Divided into 50-80 terminal bronchioles
  38. Terminal Bronchioles
    • The final branches of the conducting division
    • Have no mucous glands or goblet cells
    • Have cilia so that mucus draining into them from the higher passages can be driven back, preventing congestion of them and the alveoli
    • Gives off two or more respiartory bronchioles
  39. Respiratory Bronchioles
    • Have alveoli budding from their walls
    • The beginning of the respiartory division because of their alveoli participate in gas exchange
    • Have scanty smooth muscle, and smallest are nonciliated
    • Divides into 2-10 elongated alveolar ducts
  40. Alveolar Ducts
    • Thin-walled passages
    • Smaller divisions
    • Have nonciliated simple squamous epithelium
    • End in alveolar sacs
  41. Alveolar Sacs
    Grapelike clusters of alveoli arrayed around a central space called the atrium
  42. *******Conducting Division
    • Where there are no alveoli
    • Tissue walls are too thick for any exchange of oxygen or carbon dioxide with blood
    • Nasal cavity -> pharynx -> trachea -> main bronchus -> lobar bronchus -> segmental bronchus -> bronchiole -> terminal bronchiole
  43. Respiratory Division
    • Have alveoli along the walls
    • Engage in gas exchange
    • Respiratory bronchiole -> alveolar duct -> atrium -> alveolus
  44. Lung
    • Spongy mass composed of 150 million little sacs, alveoli
    • Provide a large surface for gas exchange
    • Do not ventilate themselves
    • Have only smooth muscle in the walls of the bronchi and bronchioles
  45. Squamous (Type I) Alveolar Cells
    • Cover about 95% of the alveolar surface area
    • Thinness allows for rapid gas diffusion between the air and blood
  46. Great (Type II) Alveolar Cells
    • Cover about 5% of the alveolar surface area
    • Round to cuboidal
    • Cover less surface area
    • Repair the alveolar epithelium when squamous cells are damaged
    • Secrete pulmonary surfactant
    • -Without it, the walls of a deflating alveolus wound cling together making it hard to reinflate them on the next inhalation
  47. Pulmonary Surfactant
    A mixture of phospholipids and protein that coats the alveoli and smallest bronchioles and prevents them from collapsing when one exhales
  48. Alveolar Macrophages (Dust Cells)
    • Most abundant cells in lungs
    • Wander the lumens of the alveoli and connective tissue between them
    • Keep the alveoli free of debris by phagocytizing dust particles that escape the mucus in higher parts
  49. Respiratory Membrane
    • Barrier between the alveolar air and blood
    • Consists of only squamous alveloar cell, squamous endothelial cell of the capillary, and their shared basement membrane
    • Low capillary blood pressure prevents the rupture of this
  50. Visceral Pleura
    • Serous membrane
    • Extends into the fissures
  51. Parietal Pleura
    • At the hilum
    • Visceral pleura turns back on itself
    • Adheres to the mediastinum, inner surface of ribcage, and superior surface of diaphragm
    • Pulmonary ligament connects it to the diaphragm
  52. Pleural Cavity
    • Space between the parietal and visceral pleurae
    • Does not contain a lung, but wraps around it
    • Contains nothing but a film of slippery pleural fluid
    • Only a potential space, no room between the membranes
  53. Pleurae and Pleural Fluid Functions
    • Reduction of friction
    • Creation of pressure gradient
    • Compartmentalization
  54. Reduction of Friction
    Pleural fluid acts as a lubricant that enables the lungs to expand and contract with minimal friction
  55. Creation of Pressure Gradient
    The pleurae play a role in the creation of one that expands the lungs when one inhales
  56. Compartmentalization
    The pleurae, mediastinum, and pericardium compartmentalize the thoracic organs and prevent infections of one organ from spreading easily to neighboring organs
  57. Smooth Muscle of Lungs
    Adjusts the diameter of the airway and affects the speed of airflow, but it does not expand or shrink the lungs or create the airflow
  58. Air Flows In
    • Increase the volume and lower the pressure in the thoracic cavity
    • External intercostals raise up, widen thoracic cavity
    • Diaphragm descends and increases depth of thoracic cavity
  59. Air Flows Out
    Reduce thoracic volume and raise pressure
  60. Forced Expiration
    • Internal intercostals depresses ribs 1-11, narrow thoracic cavity
    • Diaphragm ascends and reduces depth of thoracic cavity
  61. Neural Control of Breathing
    • Depends on repetitive stimuli from the brain
    • Ceases if the nerve connections to the thoracic muscles are severed or if the spinal cord is severed high on the neck
    • Skeletal muscles cannot contract without nervous stimulation
    • Involves the well-orchestrated action of multiple muscles, requiring a central coordinating mechanism
  62. 2 Breathing Control Methods of Brain
    • Cerebral and conscious, enabling us to inhale or exhale at will
    • Unconscious and automatic
  63. Autonomic, unconscious cycle of breathing
    • Controlled by 3 pairs of respiratory centers in the reticular formation of the medulla oblongata and pons
    • One of each on the right and left sides of brainstem
    • Ventral respiratory group
    • Dorsal respiratory group
    • Pontine respiratory group
  64. *****Ventral Respiratory Group
    • Primary generator of the respiratory rhythm
    • -Receives input from the dorsal one to modify
    • An elongated nucleus in the medulla with 2 commingled webs of neurons
    • -Inspiratory and expiratory neurons
    • -Each form a reverberating neural circuit
    • Controls the automatic, unconscious cycle of breathing
  65. Ventral Respiratory Group: Inspiratory Neurons
    • In quiet breathing, it fires for about 2 seconds at a time
    • Issues nerve signals to intergrating centers in the spinal cord
    • Output from the spinal centers travels by phrenic nerves
    • From intercostal nerves to the external intercostal muscles
    • Contraction of these muscles enlarges the thoracic cage causing inspiration
    • As long as these are firing, the inhibit the expiratory neurons
  66. Ventral Respiratory Group: Expiratory Neurons
    • Inhibit inspiratory neurons
    • Elastic recoil of the thoracic cage expels air from the lungs
    • Normally last 3 seconds
  67. Dorsal Respiratory Group
    • An integrating center that receives input from several sources: a respiratory center in the pons, a chemosensitive center of the anterior medulla oblongata, chemoreceptors in certain major arteries, and stretch and irritant receptors in the airway
    • Issues outpu to the VRG that modifies the respiratory rhythm to adapt to varying conditions
  68. Pontine Respiratory Group
    • Each side of the pons
    • Modifies the rhythm of the VRG
    • Receives input from higher brain centers including the hypothalmus, limbic system, and cerebral cortex
    • Issues output to both the DRG and VRG
    • Hastens or delays the transition from inspiration to expiration
    • Adapts breathing to special circumstances
  69. Central Chemoreceptors
    • Brainstem neurons that respond to changes in the pH of the cerebrospinal fluid
    • Concentrated on each side of the medulla oblongata
    • pH reflects the CO2 level in the blood
    • By regulating respiration to maintain a stable pH, the respiratory centers also ensure a stable blood CO2 level
  70. Peripheral Chemoreceptors
    • Located in the carotid and aortic bodies of large arteries above heart
    • Respond to O2 and CO2 content of blood, but most of all pH
    • Carotid bodies communicate with brainstem by way of glossopharyngeal nerves
    • Aortic bodies by way of vagus nerves
    • -Sensory fibers enter the medulla and synapse with neurons of the DRG
  71. Stretch Receptors
    • Found in the smooth muscle of the bronchi and bronchioles and in the visceral pleura
    • Respond to inflation of lungs and signal the DRG by vagus nerves
    • Excessive inflation triggers inflation reflex
  72. Inflation Reflex
    A protective somatic reflex that strongly inhibits the I neurons and stops inspiration
  73. Irritant Receptors
    • Nerve endings amid the epithelial cells of the airway
    • Respond to smoke, dust, pollen, chemical fumes, cold air, and excess mucus
    • Transmit signals by way of vagus nerves to the DRG
    • DRG returns signals to the respiratory and bronchial muscles
    • Results in shallower breathing, breath-holding, or coughing
  74. Alveolar Ventilation
    • Air that actually enters the alveoli becomes available for gas exchange
    • In a state of relaxation, parasympathetic stimulation keeps airway somewhat constricted, minimizing dead space, ventalating more alveoli
    • In a state of arousal, sympathetic nervous system dilates the airway, increasing airflow
  75. Anatomical Dead Space
    • The conducting division where air cannot exchange gases with blood
    • Typically about 1mL per pound of body weight
    • In some diseases, it can be greater because some alveoli lack blood flor or because the pulmonary membrane is thickened by edema or fibrosis
  76. Physiological Dead Space
    The sum of anatomical dead space and any pathological alveolar dead space that may exist
  77. ******Air
    Consists of about 78.6% nitrogen, 20.9% oxygen, 0.04% carbon dioxide
  78. Alveolar Gas Exchange
    • Air in the alveolus is in contact with the film of water covering the alveolar epithelium
    • Oxygen must dissolve in the water and pass through the respiratory membrane separating the air from the bloodstream to get in the blood
    • Carbon dioxide must pass the other way and diffuse out of the water film into the alveolar air to leave the blood
    • Back-and-forth traffic of O2 and CO2 across the respiratory membrane
  79. Blood Entering Lungs
    • PO2= 40mmHg
    • PCO2= 46mmHG
  80. Blood Leaving Lungs
    • PO2= 95mmHG
    • PCO2= 40mmHG
  81. Carbon Dioxide
    Transported in 3 forms: carbonic acid, carbamino compounds, and dissolved gas
  82. Carbonic Acid
    90% is hydrated to form this which then dissociates into bicarbonate and hydrogen ions
  83. Carbamino Compounds
    • 5% binds to amino groups of plasma proteins and hemoglobin to form this
    • Carbon dioxide does not compete with oxygen because CO2 and O2 bind to different sites on a hemoglobin molecule
    • -Oxygen to heme moiety and CO2 to polypeptide chains
    • Hemoglobin can transport both at the same time
  84. Dissolved Gas
    • 5% of CO2 is carried in the blood by this
    • Carbonated soft drinks and sparkling wines
  85. *******Carbon Dioxide Loading
    • Aerobic respiration produces a molecule of CO2 for every molecule of O2 it consumes
    • CO2 diffuses into the bloodstream, where it is carried in 3 forms
    • Most of it reacts with water to form bicarbonate
    • -Occurs slowly in the blood plasma, but faster in the RBCs where it's catalyzed by the enzyme carbonic anydrase
    • -Most common form
    • Chloride-bicarbonate exchanger pumps most of the HCO3- out of RBC in exchange for Cl- from the blood plasma
  86. 4 Factors of Adjustment of Oxygen for Individual Tissues
    • Ambient PO2
    • Temperature
    • The Bohr effect
    • BPG
  87. Ambient PO2
    • Since an active tissue consumes oxygen rapidly, this of its tissue fluid remains low
    • A low one releases more oxygen
  88. Temperature
    • When it rises, it promotes oxygen unloading
    • Active tissues are warmer and extract more oxygen from the blood passing through them
  89. Bohr Effect
    • Active tissues generate extra CO2, which raises the H+ concentration and lowers the pH of blood
    • Hydrogen ions weaken the bond between hemoglobin and oxygen, promoting oxygen unloading
    • Less pronounced at high PO2 present in lungs, pH has little effect on pulmonary oxygen
    • More pronounced at low PO2 present in systemic capillaries
  90. *******BPG
    • Erythrocytes have no mitochondria and meet their energy needs by anaerobic fermentation
    • Binds to hemoglobin and promotes oxygen unloading
    • Elevated body temperature stimulates this sythesis, as do thyroxine, growth hormone, testosterone, and epinephrine
    • All of these hormones promote oxygen unloading to the tissues
    • Ereythrocytes low in it do not unload 02 very well
  91. Squamous-Cell Carcinoma
    • Basal cells of the bronchial epithelium multiply
    • Ciliated pseudostratified epithelium transforms into the stratified squamous type
    • As the dividing epithelial cells invade underlying tissues of the bronchial wall, the bronchus develops bleeding lesions
    • Dense swirled masses of keratin appear in the lung parenchyma and replace functional respiratory tissue
  92. Adenocarcinoma
    Originates in the mucus glands of the lamina propria
  93. Small-Cell Carcinoma
    • Clusters of cells that resemble oat grains
    • Originates in the main bronchi but invades the mediastinum and metastasizes quickly to other organs
  94. Lung Cancer
    • Over 90% of tumors originate in the mucous membranes of large bronchi
    • As the tumor invades the bronchial wall and grows around it, it compresses the airway and may cause collapse of more distal parts of the lung
    • Growth of tumor produces a cough with blood
    • Common sites of metastasis are the pericardium, heart, bones, liver, lymph nodes, and brain
  95. Digestive System
    • Organ system that processes food, extracts nutrients, and eliminates the residue
    • Ingestion
    • Digestion
    • Absorption
    • Compaction
    • Defecation
  96. Mechanical Digestion
    • The physical breakdown of food into smaller particles
    • Achieved by the cutting and grinding action of the teeth and the churning contractions of the stomach and small intestine
    • Exposes more food surface to the action of digestive enzymes
  97. *********Chemical Digestion
    • A series of hydrolysis reactions that break dietary macromolecules into their monomers: polysaccharides into monosaccharides, proteins into amino acids, fats into monoglycerides and fatty acids, and nucleic acids into nucleotides
    • Carried out by digestive enzymes produced by the salivary glands, stomach, pancreas, and small intestine
    • Some nutrients are already present and are absorbed without being digested: vitamins, free amino acids, minerals, cholesterol, and water
  98. Digestive Tract
    Includes the mouth, pharynx, esophagus, stomach, small intestine, and large intestine
  99. Accessory Organs
    Teeth, tongue, salivary glands, liver, gallbladder, and pancreas
  100. ********Tissue Layers of Digestive Tract
    • Most inner to most outer:
    • Lamina propria
    • Muscularis mucosae
    • Mucosa
    • Submucosa
    • Muscularis externa
    • Serosa
  101. Tissue Layers of Digestive Tract: Mucosa
    • Epithelium, simple columnar, but stratified squamous in oral cavity to the esophagus and in lower anal canal
    • Lamina propria, loose connective tissue
    • Muscularis mucosae, thin layer of smooth muscle
  102. Tissue Layers of Digestive Tract: Muscularis Externa
    • Inner circular layer encircle the tract
    • -Some areas, it's thickened to form sphincters
    • Outer longitudinal layer
    • Responsible for the motility that propels food and residue through the digestive tract
  103. Tissue Layers of Digestive Tract: Serosa
    • Areolar tissue
    • Mesothelium, simple squamous
    • Pharynx, most of the esophagus, and rectume have none, but are surrounded by fibrous connective tissue called adventitia
  104. Muscularis Mucosae
    • Tenses the mucosa, creating grooves and ridges that enhance its surface area and contact with food
    • Improves the efficiency of digestion and nutrient absorption
    • Has an abundance of lymphocytes and lymphatic nodules
  105. Tissue Layers of Digestive Tract: Submucosa
    A thicker layer of loose connective tissue containing blood vessels and lymphatics, a nerve plexus, and in some places, glands that secrete lubricating mucus into the lumen
  106. Enteric Nervous System
    • Nervous network found in the esophagus, stomach, and intestines
    • Regulates digestive tract motility, secretion, and blood flow
    • Can function independently from the CNS
    • Composed of 2 networks:
    • Submucosal plexus
    • Myenteric plexus
  107. Myenteric Plexus
    • Parasympathetic ganglia and nerve fibers between layers of muscularis exterma
    • Parasympathetic preganglionic fibers terminate in the ganglia of here
    • Postganglionic fibers arising here also pass through the muscularis externa's inner circular layer and contribute to the submucosal plexus
    • Controls peristalsis and other contractions
  108. Submucosal Plexus
    Controls movements of the muscularis mucosae and glandular secretion of the mucosa
  109. ******Mesenteries
    • Hold the abdominal viscera in their proper relationship to each other and prevent the small intestine from becoming twisted and tangled by its own contractions or changes in body position
    • Provide passage for the blood vessels and nerves that supply the digestive tract
    • Contain many lymph nodes and lymphatic vessels
    • Serous membranes that suspend the stomach and intestines from the abdominal walll
  110. Posterior (Dorsal) Mesentery
    • A translucent 2-layered membrane extending to the digestive tract
    • When it reaches an organ, the 2 layers separate and pass around opposite sides forming the serosa
  111. Anterior (Ventral) Mesentary
    • May hang freely in the abdominal cavity or attach to the anterior abdominal wall or other organs
    • Two layers come together on far side of organ and continue as another sheet of tissue
    • Lesser omentum
    • Greater omentum
  112. Lesser Omentum
    Extends the short distance from the liver to the right superior margin of stomach
  113. Greater Omentum
    • Hangs like an apron from the left inferior margin of stomach, loosely covering the small intestine
    • Turns back on itself and passes upward, behind the superficial layer, forming a deep pouch
  114. Omenta
    • Contain many lymph nodes and lymphatic vessels, blood vessels, and nerves
    • Adhere to perforations or inflammed areas of the stomach or intestines, contribute immune cells to the site, and isolate infections that might otherwise give rise to peritonitis
  115. Mouth
    • Ingestion, taste, and other sensory responses to food, mastication, chemical digestion, swallowing, speech, and respiration
    • Lined with stratified squamous epithelium
    • -Keratinized in areas subject to the greatest food abrasion (gums and hard palate)
    • -Nonkeratinized in other areas
  116. *******Tongue
    • Manipulates food between the teeth while it avoids being bitten
    • Can extract food particles from teeth after a meal, and is sensitive enough to feel a stray hair
    • Covered with nonkeratinized stratified squamous epithelium
    • Bumps called lingual papillae- taste buds
    • Vallate papillae
    • Terminal papillae- behind vallate
  117. Mastication
    Breaks food into pieces small enough to be swallowed and exposes more surface to the action of digestive enzymes
  118. Saliva
    • Moistens and cleanses mouth, inhibits bacterial growth, dissolves molecules to stimulate taste buds, digests a little starch and fat, and makes swallowing easier by making a bolus
    • Hypotonic solution
    • Mucus
    • Electrolytes
    • Lysozyme
    • Immunoglobulin A
    • Salivary amylase
    • Lingual lipase
  119. Lysozyme
    Enzyme that kills bacteria
  120. Immunoglobulin A
    Antibacterial antibody
  121. Salivary Amylase
    An enzyme that begins starch digestion in mouth
  122. Lingual Lipase
    Enzyme that begins fat digestion in the mouth
  123. *******Intrinsic Salivary Glands
    • Indefinite number of small glands dispersed among the other oral tissues
    • Secrete saliva at a fairly constant rate
    • Contains ligual lipase and lysozyme
  124. *******Extrinsic Salivary Glands
    • 3 pairs of larger organs located outside of the oral mucosa
    • -Parotid glands
    • -Submandibular glands
    • -Sublingual glands
    • Secrete 1-1.5L of saliva per day
  125. Parotid Glands
    • Located beneath the skin
    • Mumps is an inflammation and swelling caused by a virus
  126. ********Submandibular Glands
    Duct empties into the mouth at a papilla on the side of the ligual frenulum, near the lower central incisors
  127. Sublingual Glands
    • Located in the floor of the mouth
    • Have multiple ducts that empty into the mouth posterior to the papillae of the submandibular ducts
  128. *******Lower Esophageal Sphincter
    • Prevents stomach acid from regurgitating into the esophagus
    • Protects the esophageal mucosa from the erosive effect of stomach acid
    • Heartburn
  129. Stomach: Lesser Curvature
    Margin that extends for the short distance from esophagus to duodenum along the medial to superior aspect, facing the liver
  130. Stomach: Greater Curvature
    Longer margin from esophagus to duodenum on the lateral to inferior aspect
  131. Stomach
    • Divided into 4 regions
    • -Cardiac region, fundus, body, pyloric region
    • Receives parasympathetic nerve fibers from the vagus nerves and sympathetic fibers from the celiac ganglia
    • Supplied with blood by branches of the celiac trunk
    • All blood drained enters the hepatic portal circulation and filters through the liver before returning to the heart
  132. Pyloric Sphincter
    Regulates the passage of chyme into the duodenum
  133. Mucous Cells
    • Secrete mucus, predominate in the cardiac and pyloric glands
    • In gastric glands, they are concentrated in the narrow neck of the gland where it opens into the gastric pit
  134. Regenerative Cells
    • Found in the base of the pit and neck of the gland
    • Divide rapidly and produce a continual supply of new cells
    • Newly generated cells migrate upwards to the gastric surface as well as downwards into the glands to replace cells that die
  135. *******Parietal Cells
    • Found mostly in the upper half of the gland
    • Secrete hydrochloric acid, intrinsic factor, and ghrelin
    • Found mostly in the gastric glands, but a few in the pyloric glands
  136. Chief Cells
    • Secrete the enzymes gastric lipase and pepsinogen
    • Dominate the lower half of the gastric glands
    • Absent from pyloric and cardiac glands
  137. Enteroendocrine Cells
    • Secrete hormones and paracrine messengers that regulate digestion
    • Occur in all regions of the stomach, but are most abundant in lower ends of gastric and pyloric glands
    • At least 8 kinds, each produces a different chemical messenger
  138. *******Hydrochloric Acid
    • Activates pepsin and lingual lipase
    • Breaks up connective tissues and plant cell walls; helping to liquefy food and form chyme
    • Converts ingested ferric ions to ferrous ions
    • Contributes to nonspecific disease resistance by destroying most ingested pathogens
  139. Pepsin
    • Secreted by chief cells
    • Pepsinogen (zymogen)
    • Hydrochloric acid removes some amino acids and converts it to this
    • Has an autocatalytic effect
    • Digests dietary proteins to shorter peptide chains, which then pass to the small intestine, where digestion is complete
  140. Gastric Lipase
    • Secreted by chief cells
    • Digests 10-15% of dietary fat in stomach
    • Remainder is digested in small intestine
  141. Intrinsic Factor
    • Secreted by parietal cells
    • Essential for the absorption of B12 by the small intestine
    • Binds B12 and intestinal cells then absorb this complex by receptor-mediated endocytosis
    • Without B12, hemoglobin can't be synthesized and anemia develops
  142. Cephalic Phase
    • The stage in which the stomach responds to the sight, smell, taste, or thought of food
    • Sensory and mental inputs converge on the hypothalamus, which relays signals to the medulla oblongata
    • Vagus nerve fibers stimulate the enteric nervous system of the stomach
    • Stomach stimulates gastric secretion
  143. Gastric Phase
    • A period in which swallowed food and semidigested protein activate gastric activity
    • Stretches the stomach and raising pH contents
    • Stimulated by acetylcholine (parasympathetic nerve fibers), histamine (paracrine secretion), and gastrin (enteroendocrine G cells in pyloric glands)
    • -Stimulate parietal cells to secrete HCl and intrinsic factor
    • Chief cells secrete pepsinogen in response to gastrin
    • Positive feedback loop
    • -Protein -> amino acids -> G cells -> more gastrin
  144. Intestinal Phase
    • A stage in which the duodenum responds to arriving chyme and moderates gastric activity through hormones and nervous reflexes
    • Stretching of duodenum accentuates vagovagal reflexes that the stomach, and peptides and amino acids in the chyme stimulate G cells to secrete more gastrin that stimulates the stomach more
    • Trigger enterogastric reflex
  145. Liver
    • Secretes bile
    • 4 lobes
    • Round ligament carries blood from umbilical cord to the liver of a fetus
    • Hepatic portal vein and bile travel through lesser omentum
  146. Hepatic Portal Vein
    • Liver receives 70% of blood from here
    • Receives blood from the stomach, intestines, pancreas, and spleen
    • All nutrients absorbed, reach the liver by this route except for lipids
  147. Hepatic Arteries
    • Liver recieves 30% of blood from here
    • Exits the aorta at the celiac trunk -> common hepatic artery -> hepatic artery -> right and left hepatic arteries which enter the liver and porta
    • Deliver oxygen and other materials to the liver
  148. Gallbladder
    • Store and concentrates bile
    • Simple columnar epithelium
    • When waste products become concetranted, they may form gallstones
    • Biles enters by filling the bile duct, then overflowing into it
    • Between meals, it absorbs water and electrolytes from bile and concentrates it
  149. Pancreas
    • Spongy retroperitoneal gland posterior to the greater curvature of the stomach
    • Endocrine and exocrine gland
    • -Pancreatic islets secrete insulin and glucagon
    • Has an accessory duct that allows juices to be released into duodenum even while bile is not
    • Trypsinogen, chymotrypsinogen, and procarboxypeptidase
  150. Trypsinogen
    • When secreted into the itnestinal lumen, it is converted to trypsin by enterokinase
    • Autocatalytic
    • Positive feedback loop
  151. Pancreatic Amylase
    Digests starch
  152. Pancreatic Lipase
    Digests fat
  153. Ribonuclease
    Digests RNA and DNA
  154. Regulation of Pancreatic Juice and Bile
    • Acetylcholine
    • Cholecystokinin
    • Secretin
  155. Acetylcholine
    • Coming from the vagus and enteric nerves
    • Stimulates the pancreatic acini to secrete their enzymes even durn cephalic phase of gastric control, before food is swallowed
    • Enzymes remain stored in pancreatic acini and ducts in preparation for release later when chyme enters the duodenum
  156. Cholecystokinin
    • Secreted by the mucosa of the duodenum and proximal jejunum
    • In response to fats in the small intestine
    • Stimulates the pancreatic acini to secrete enzymes
    • Induces contractions of the gallbladder and relaxation of the hepatopancreatic sphincter, discharging bile into the duodenum
  157. Secretin
    • Produced in response to the acidity of chyme from the stomach
    • Stimulates the ducts of both the liver and pancreas to secrete a lot of sodium bicarbonate
    • In pancreas, this flushes the enzymes into the duodenum
    • Sodium bicarbonate buffers the HCl arriving from the stomach
    • Carbonic acid breaks down to CO2 and H2O
    • -CO2 is absorbed in the blood and exhaled
    • Salt water is left in small intestine
  158. Duodenum
    • Receives the stomach contents, pancreatic juice, and bile
    • Stomach acid is neutralized here
    • Fats are physically broken up by the bile acids
    • Pepsin is inactivated by elevated pH
    • Pancreatic enzymes take over the job of chemical digestion
  159. Jejunum
    Most digestion and nutrient absorption occurs here
  160. Ileum
    • Walls are thinner than jejunum, less muscular
    • Prominent lymphatic nodules in clusters called Peyer's patches
  161. *******Lacteal
    • Absorbs most lipids (triglycerides)
    • Give its contents a milky appearance
    • Core of the villus has a few smooth muscle cells that contract periodically
    • -Enhances mixing of chyme in intestinal lumen and milks lymph down here to the larger lymphatics of the submucosa
    • Located in small intestine
  162. Intestinal Crypts
    • Numerous pores that open into tubular glands on the floor of the small intestine
    • Upper half has enterocytes and goblet cells
    • Lower half has dividing stem cells
    • Life span of 3-6 days
  163. Paneth Cells
    • Clustered at the base of each crypt
    • Secrete lysozyme, phospholipase, and defensins
  164. Duodenal Glands
    Secrete an abundance of bicarbonate-rich mucus that neutralizes stomach acid and shields the mucosa from its erosive effects
  165. Contractions of Small Intestine Functions
    • Mix chyme with intestinal juice, bile, and pancreatic juice, allowing these fluids to neutralize acid and digest nutrients more effectively
    • Churn chyme and bring it into contact with the mucosa for contact digestion and nutrient absorption
    • Move residue toward the large intestine
  166. Segmentation
    • A movement in which stationary ringlike constrictions appear at several places along the intestne and then relax as new constrictions form elsewhere
    • Most common type of intestinal contraction
    • Churn the contents
    • Causes slow progression of the chyme toward the colon
    • Intensity of contractions is modified by nervous and hormonal influences
    • Declines when most nutrients have been absorbed, peristalsis begins
  167. Water
    • Digestive tract receives about 9L per day
    • -0.7 in food, 1.6 in drink, and 6.7L in gastrointestinal secretions: saliva, gastric juice, bile, pancreatic juice, and intestinal juice
    • 8L is absorbed by the small intestine
    • 0.8L is absorbed by the large intestine
    • 0.2L for fecal output
  168. Diarrhea
    • Occurs when the large intestine absorbs too little water
    • When the intestine is irritated by bacteria and feces pass through too quickly for adequate reabsorption, or when the feces contain abnormally high concentrations of a solute that opposes osmotic absorption of water
  169. Constipation
    • Occurs when fecal movement is slow
    • Too much water is reabsorbed
    • Feces becomes hardened
    • Can result from a lack of dietary fiber, exercise, emotional upset, or laxative abuse
  170. Large Intestine
    • Cecum, colon, rectum, and anal canal
    • Harbors about 800 species of bacteria called the bacterial flora
    • -Mutually beneficial relationship with many of these
    • -Provide them with room and board while they provide us with nutrients from our food that we cannot extract on our own
  171. Appendix
    • Attached to the cecum
    • Densly populated with lymphocytes
    • Significant source of immune cells

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