Flashcards in Digestive/Endocrine Deck (68):
1
Liver Role in Digestion
Secretion of bile
2
Hepatic Triad
Hepatic Portal Vein
Bile Duct
Hepatic Artery
3
Hepatic Portal Vein
70% of blood that goes through the liver
4
Bile Duct
Collection of bile from all cells
5
Hepatic Artery
30% of blood that goes through the liver
6
Gallbladder
Stores bile produced in the liver and concentrates it
7
Pathway of Bile Secretion
1. Bile capillaries
2. Hepatic ducts create common hepatic duct
3. Cystic duct (gallbladder) and common hepatic duct make common bile duct
4. Common bile duct and pancreatic duct empty into duodenum
8
Components of Bile
1. Water and cholesterol
2. Bile salts (Na and K)
3. Bile pigments (bilirubin) from hemoglobin molecule
9
Acini
Dark clusters in the pancreas
Exocrine
99% of pancreas
Produce pancreatic juice
10
Islets of Langerhans
1% of gland
Pale staining cells
Produce hormones
11
Pancreatic Juice Components
Water, enzymes, and sodium bicarbonate
12
Digestive Enzymes of Pancreas
Pancreatic amylase
Pancreatic lipase
Ribonuclease
Deoxyribonuclease
Zymogens
13
Zymogens of Pancreas
Trypsinogen
Chymotrypsinogen
Procarboxypeptidase
14
Activation of Zymogens
Trypsinogen converted to trypsin by intestinal epithelium
Trypsin converts other two zymogens as well as digests dietary protein
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Regulation of Pancreatic Secretions
Acetylcholine
Secretin
Cholecystokinin
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Acetylcholine in Pancreas
Vagal origin
Stimulates acini to secrete enzymes during cephalic phase
17
Secretin in Pancreas
Acidity in intestine causes increased sodium bicarbonate release
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Cholecystokinin in Pancreas
Fats and proteins cause increased digestive enzyme release, contraction of gallbladder, and relaxation of Sphincter of Oddi
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Equations for Regulation of Pancreatic Secretions
HCl + NaHCO3 --> NaCl + H2CO3 --> NaCl + H2O + CO2
H2O goes into stomach, CO2 goes into the blood
Decreases acidity, lowers pH
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Anatomy of Small Intestine
Duodenum
Jejunum
Ileum
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Where does all absorption occur?
Small intestine
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Histology of Small Intestine
1. Circular Folds (increase surface area, slow progress of chyme)
2. Gastric Pits (secrete chemicals)
3. Villi (contains arteriole, blood capillaries, venule, and lymphatic capillary)
4. Microvilli (contain enzymes that complete chemical digestion; contain brush border enzymes)
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Functions of Microvilli
Absorption and digestion
Significant cell division within intestinal glands
Rupture and release digestive enzymes and proteins
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Cells of Intestinal Glands
1. Microvilli
2. Goblet Cell
3. Enteroendocrine Cell
4. Paneth Cell
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Enteroendocrine Cell
Secretes secretin, CCK, or gastric inhibitory peptide
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Paneth Cell
Secretes lysozyme
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Segmentation
Local mixing of chyme with intestinal juices
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Digestion of Carbohydrates
1. Mouth: salivary amylase
2. Esophagus and Stomach: nothing
3. Duodenum: pancreatic amylase
4. Brush border enzymes (maltase, sucrase, and lactase) act on disaccharides to produce monosaccharides
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Digestion of Proteins
1. Stomach: HCl denatures proteins and pepsin turns into peptides
2. Pancreas: trypsin and chymotrypsin take over
3. Carboxypeptidase: removes AA from carboxyl group
4. Aminopeptidase: removes AA from nitrogenous group
5. Dipeptidase: splits dipeptides in the middle and releases the last two free AA
30
Protein Absorption
Brush border enzymes produce amino acids that are absorbed into the intestinal epithelial cells and into the bloodstream
31
Digestion of Lipids
1. Mouth: lingual lipase
2. Small Intestine: emulsification by bile; pancreatic lipase splits into fatty acids and monoglycerides
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Fat Digestion Sequence
Fat globule --> Monoglyceride --> Micelle
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Absorption of Lipids
Fats are rebuilt and coated with protein to form chylomicrons in epithelial cells
34
Chylomicrons
Travel in lymphatic system to reach veins near the heart
Removed from the blood by liver and fat tissue
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Digestion of Nucleic Acids
Pancreatic juice contains ribonuclease and deoxyribonuclease
Transported across intestinal epithelium
36
Absorption of Electrolytes
Enter epithelial cells by diffusion and secondary active transport
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Absorption of Vitamins
Absorbed unchanged
Fat soluble travel in micelles
Water soluble absorbed by diffusion
B12 combines with intrinsic factor
38
Absorption of Water
Small intestine reabsorbs 8 L
Large intestine reabsorbs 0.8 L
0.2 L passed in fecal matter
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Four Regions of Large Intestine
Cecum
Appendix
Rectum
Anal Canal
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Histology of Large Intestine
Mucosa: smooth tube, simple columnar cells, goblet cells
Muscular layer: outer longitudinal muscle
Serosa: visceral peritoneum
Appendix: contains large amounts of lymphatic tissue
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Intestinal Microbes
Digest cellulose, pectin, plant polysaccharides
Absorb digested material
Bacteria synthesize vitamins B and K
42
Anatomy of Anal Canal
3 cm in length
Longitudinal ridges separated by mucus secreting anal sinuses
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Defecation
1. Feces stretch rectum and stimulate stretch receptors
2. Spinal reflex stimulates contraction of the rectum
3. Spinal reflex relaxes internal sphincter
4. Impulses from the brain keep external sphincter contracted
44
Endocrine System
Hormones released into the bloodstream travel throughout the body
Results may take hours, but last a long time
45
Nervous System
Certain parts release hormones into the blood
Rest releases neurotransmitters to excite or inhibit nerve, muscle, and gland cells
Results in milliseconds, brief duration of effects
46
Cell Communications
Gap Junctions
Neurotransmitters
Paracrine Hormones
Hormones
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Paracrine Hormones
Secreted into tissue fluids to effect nearby cells
48
Similarities in Nervous and Endocrine Systems
Secrete norepinephrine, dopamine, and ADH
Systems regulate each other
49
Exocrine Glands
Secretes products into ducts which empty into body cavities or body surface
Extracellular effects
Sweat, oil, mucous, and digestive glands
50
Endocrine Glands
Secrete products into bloodstream
Intracellular effects
Pituitary, thyroid, parathyroid, adrenal, pineal
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Anterior and Posterior Pituitary Glands
Posterior pituitary gland develops from hypothalamus
Anterior pituitary gland develops from the roof of the mouth
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Hypothalamus
Master of the endocrine system
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Anatomy of Pituitary Gland
Anterior lobe: adenohypophysis
Posterior lobe: neurohypophysis
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Posterior Pituitary Gland
Releases oxytocin and ADH
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Anterior Pituitary Gland
Releases follicle stimulating hormone, lutenizing hormone, thyroid stimulating hormone, ACTH, prolactin, and growth hormone
56
Tropic Hormones
Target other endocrine glands
1. Gonadotropins (FSH and LH)
2. Thyroid stimulating hormone
3. ACTH
57
Growth Hormone
Secreted by somatotropes of anterior pituitary
Promotes tissue growth by affecting mitosis
Indirectly stimulates liver to produce insulin growth factor
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Actions of GH
Protein synthesis
Lipid metabolism
Carbohydrate metabolism
Electrolyte balance
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Protein Synthesis of GH
Translates mRNA into proteins
Increases amino acids into the cell to support protein synthesis
60
Lipid Metabolism of GH
Supports energy needs
Protein-sparing effect
61
Carbohydrate Metabolism of GH
Glucose-sparing effect by mobilizing fatty acids, reducing dependence on glucose to avoid competition with the brain
Stimulates gluconeogenesis in the liver
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Electrolyte Balance of GH
Na, K, Cl retention by kidneys
Increases calcium absorption by the small intestine
63
Thyroid Stimulating Hormone
Hypothalamus regulates thyrotroph cells
Thyrotropin releasing hormone (TRH)
Thyrotroph cells produce TSH
TSH stimulates synthesis and secretion of T3 (triiodothyronine) and T4 (thyroxine)
64
Follicle Stimulating Hormone
Gonadotrophin releasing hormone (GnRH)
Gonadotrophic cells release FSH
65
FSH Functions
Initiates formation of follicles within the ovary
Stimulates follicle cells to secrete estrogen
Stimulates sperm production in the testes
66
Lutenizing Hormone
Gonadotrophin releasing hormone (GnRH)
Gonadotrophic cells produce LH
In females, LH stimulates ovulation
In males, LH stimulates interstitial cells to secrete testosterone
67
Prolactin
Prolactin inhibiting hormone (PIH) prevents prolactin release
Lactotrophic cells produce prolactin
Suckling reduces levels of PIH and prolactin levels rise along with milk production
68