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The Digestive System; Alyssa Najarro Period 1 - Coggle Diagram

- - - - -Ureters: transport urine from kidneys to urinary bladder
      - -Urinary bladder: temporary storage reservoir for urine
      - -Urethra: transports urine out of body
      - Anatomy of the Kidney
        
        Internal kidney has three distinct regions;
        
        II. Renal medulla: deep to cortex, composed of cone-shaped medullary (renal) pyramids
        -Broad base of pyramid faces cortex
        -Papilla, tip of pyramid, points internally
        -Renal pyramids are separated by renal columns, inward extensions of cortical tissue
        -Lobe: medullary pyramid and its surrounding cortical tissue; about eight lobes per kidney
        
        I.Renal cortex: granular-appearing superficial region
        
        III. Renal pelvis;
        Funnel-shaped tube continuous with ureter
        Minor calyces- Cup-shaped areas that collect urine draining from pyramidal papillae
        Major calyces
        -Areas that collect urine from minor calyces
        -Empty urine into renal pelvis
        
        Urine flow
        Renal pyramid → minor calyx → major calyx → renal pelvis → ureter
        
        Blood and Nerve Supply
        Kidneys cleanse blood and adjust its composition, so it has a rich blood supply
        
        Renal arteries deliver about one-fourth (1200 ml) of cardiac output to kidneys each minute
        
        Arterial flow: renal → segmental → interlobar → arcuate → cortical radiate
        
        – Venous flow: cortical radiate → arcuate → interlobar → renal veins
        
        Nephrons
        Nephrons are the structural and functional units that forms urine in the Kidneys; 1 million per kidney.
        -Two main parts;
        Renal corpuscle and Renal tubule
        
        Renal Tubule and Collecting Duct
        
        I. Proximal convoluted tubule (PCT)
        -Cuboidal cells with dense microvilli that form brush border
        -Increase surface area
        -Also have large mitochondria
        -Functions in reabsorption and secretion
        -Confined to cortex
        
        II.Nephron loop
        -Formerly called loop of Henle
        -U-shaped structure consisting of two limbs
        Descending limb
        -Proximal part of descending limb is continuous with proximal tubule
        -Distal portion also called descending thin limb; simple squamous
        epithelium
        Ascending limb
        -Thick ascending limb
        -Thin in some nephrons
        -Cuboidal or columnar cells
        
        III. Distal convoluted tubule (DCT)
        -Cuboidal cells with very few microvilli
        -Function more in secretion than reabsorption
        -Confined to cortex
        Collecting ducts
        Two cell types
        Principal cells
        -Sparse with short microvilli -
        -Maintain water and Na+
        balance
        Intercalated cells
        -Cuboidal cells with abundant microvilli
        -Two types of intercalated cells;
        A and B: both help maintain acid-base balance of blood
        -Collecting ducts receive filtrate from many nephrons
        -Run through medullary pyramids
        -Give pyramids their striped appearance
        -Ducts fuse together to deliver urine through papillae into minor calyces
        
        Physiology of Kidney
        
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- - - - -Lipases (for lipids) breaks down fats in food so they can be absorbed in the intestines
        
        -Nucleases (for nucleic acids);
        Pancreatic enzymes called ribonuclease and deoxyribonuclease*, breaking down RNA and DNA into smaller nucleic acids. These are further broken down into nitrogen bases and sugars by small intestine enzymes.
        
        Pepsin the chief digestive enzyme in the stomach, which breaks down proteins into polypeptides
        
        Trypsin is an enzyme that helps digest protein produced by the pancreas in an inactive form called trypsinogen.
        
        Deoxyribonuclease is secreted by the pancreas, that degrades DNA into shorter nucleotide fragments.
        
        Absorption of Vitamins, Electrolytes, & Water
        
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- - - - Alimentary Canal
        
        Mouth and Associated Organs
        Mouth is where food is chewed and mixed with enzyme-containing saliva that begins
        process of digestion, and swallowing process is initiated
        Associated organs include:
        -Mouth
        -Tongue
        -Salivary Glands
        -Teeth
        
        Mouth
        
        It is also referred to as the oral (buccal) cavity with the Oral Orifice being the anterior opening. The walls of the mouth is lined with stratified squamous epithelium
        
        Tongue lays on the floor of mouth
        
        Salivary Glands
        
        Teeth
        
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        Salivary glands are composed of two types of secretory cells
        -Serous cells: produce watery secretion, enzymes, ions, bit of mucin
        -Mucous cells: produce mucus
        
        Functions of saliva
        -Cleanses mouth
        -Dissolves food chemicals for taste
        -Moistens food; compacts into bolus
        -Begins breakdown of starch with enzyme amylas
        
        Functions include:
        -Gripping, repositioning, and mixing of food during chewing
        -Formation of bolus, mixture of food and saliva
        -Initiation of swallowing, speech, and taste
        -Lingual frenulum: attachment to floor of mouth
        
        Lips and cheeks
        Lips (labia): composed of fleshy orbicularis oris muscle
        Cheeks : composed of buccinator muscles
        Labial frenulum: median attachment of each lip to gum
        
        Palate
        Palate forms the roof of the mouth and has two distinct parts
        1) Hard palate: formed by palatine bones and palatine processes of maxillae with a midline ridge called raphe
        2) Soft palate: fold formed mostly of skeletal muscle
        -Closes off nasopharynx during swallowing
        -Uvula: fingerlike projection that faces downward from free edge of soft palate
        
        4) Muscularis externa
        -Muscle layer responsible for segmentation and peristalsis
        -Contains inner circular muscle layer and outer longitudinal layers
        -Circular layer thickens in some areas to form sphincters
        
        2) Submucosa
        -Consists of areolar connective tissue
        -Contains blood and lymphatic vessels, lymphoid follicles, and submucosal nerve
        plexus that supply surrounding GI tract tissues
        -Has abundant amount of elastic tissues that help organs to regain shape after storing large meal
        
        5) Serosa
        -Outermost layer, which is made up of the visceral peritoneum
        
        1) Mucosa
        Tunic layer that lines lumen
        Functions: different layers perform one or all three
        Secretes mucus, digestive enzymes, and hormones
        Absorbs end products of digestion
        Protects against infectious disease
      - -Digestion: series of catabolic steps that involves enzymes that break down complex food molecules into chemical building blocks
      - -Mechanical breakdown: includes chewing, mixing food with saliva, churning food in stomach, and segmentation.
        Segmentation: local constriction of intestine that mixes food with digestive
        juices
      - -Absorption: passage of digested fragments from lumen of GI tract into blood or lymph
      - -Propulsion: movement of food through the alimentary canal, which includes;
        -Swallowing
        -Peristalsis: major means of propulsion of food that involves alternating waves of contraction and relaxation
      - -Defecation: elimination of indigestible substances via anus in form of feces
      - Processing of food involves six essential roles:
        -Ingestion: eating