Exam 3 Vocab Flashcards
(143 cards)
1
Q
Food
A
Basic source of organic molecules to make ATP, build tissues and serve as cofactors and coenzymes
2
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Digestion
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Breaks polymers into monomers via hydrolysis reaction. Chemical and physical breakdown of food
3
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Absorption
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Takes monomers into bloodstream to be used by cells. Passing broken down food into blood or lymph
4
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Motility
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Movement of food through the tract
5
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Ingestion
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Taking food into the mouth
6
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Mastication
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Chewing food into smaller pieces and mixing with saliva for deglutination.
7
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Deglutination
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Swallowing. Coordinated contraction of 25 pairs of muscles
8
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Peristalsis
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Wave-like, one-way movement through tract. Weak and slow movement for better absorption
9
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Segmentation
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Churning and mixing in different segments while moving forward. Stronger than peristalsis
10
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Exocrine Secretion (Digestion)
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Digestive enzymes, Hal, mucus, water, HCO3-
11
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Endocrine Secretion (Digestion)
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Hormones to regulate digestion
12
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Storage and Elimination
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Temporary storage and subsequent elimination of undigested food
13
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Simple Columnar Epithelium (intestine)
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Tight junctions that prevent pathogens from entering the body. Physical barrier
14
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Immune cells
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Found in connective tissue of digestive tract to promote immune response
15
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Gastrointestinal Tract (GI tract)
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Alimentary canal: 30 feet long, from mouth to anus.
Oral cavity –> pharynx –> esophagus –> stomach –> small intestines –> large intestines –> anus
16
Q
Accessory Organs
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Teeth, tongue, salivary glands, liver, gallbladder, pancreas
17
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Mucosa
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Inner secretory and absorptive layer, may be folded to increase surface area (and have villi and microvilli usually)
18
Q
Submucosa
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Vascular layer of connective tissue –> picks up nutrients, also has some glands and nerve plexuses
19
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Muscularis
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Lots of smooth muscles but run in different directions; responsible for peristalsis and segmentation; myenteric plexus for control by the ANS
20
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Serosa
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Outer binding and protective layer
21
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Parasympathetic (Extrinsic Regulation)
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Stimulates motility and secretion (rest and digest)
22
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Sympathetic (Extrinsic Regulation)
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Inhibits peristalsis and secretion; stimulates sphincter contraction (fight or flight, inhibiting rest or digest)
23
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Hormones (Extrinsic Regulation)
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From brain and other digestive organs
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Intrinsic Sensory Neurons (Intrinsic Regulation)
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In gut wall, not part of ANS; part of enteric nervous system
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Paracrine Signals (Intrinsic Regulation)
In stomach, histamine and serotonin, released by ECL cells
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Saliva
Contains mucus = antimicrobial and salivary amylase which begins digestion of starch
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Oral (Deglutition)
Voluntary: mouth and tongue muscles
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Pharyngeal (Deglutition)
Involuntary --> uvula (nasopharynx) and epiglottis covers up the passage into the trachea (vocal cords)
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Esophageal (Deglutition)
Involuntary; controlled by swallowing center of the brain stem
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Bolus
Chewed food. moves down the esophagus to stomach via peristalsis
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Lower Esophageal (gastroesophogeal) Sphincter
Opens to allow food to pass into stomach; stays closed to prevent regurgitation
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Stomach Functions
Stores food, churns food to mix with gastric secretions, begins protein digestion (pepsin), kills bacteria in the food (Hal), moves food into small intestine as chyme.
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Stomach Structure
Food enters from esophagus into cardiac region, upper region (fondus), lower region (body), distal region (pyloric region ends at pyloric sphincter). Lining has folds called rugae
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Gastric Pits
Openings in rug that lead to gastric glands
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Mucous Neck Cells
Secrete mucus to protect stomach lining from acid
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Parietal Cells
Secrete Hal and intrinsic factor (B12 absorption too)
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Chief (zymogenic) Cells
Secrete pepsinogen (inactive form of pepsin)
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Enterochromaffin-like Cells (ECL)
Secrete histamine and serotonin (Paracrine signals)
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G Cells
Secrete gastrin (hormone)
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D Cells
Secrete somatostatin (hormone)
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Ghrelin
Signals brain to regulate hunger
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Apical Membrane (Intestines)
Faces the lumen of the intestines. Pumps H out and Cl follows passively
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Basal Membrane (intestines)
Faces capillaries. Brings Cl in, and exports HCO3 (carbonic anhydrase)
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HCl
Makes the intestines more acidic, denaturing proteins for easier digestion and converting pepsinogen into pepsin
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Pepsin
Catalyzes hydrolysis of peptide bonds in ingested proteins
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Stomach Defense
Adherent layer of mucus with alkaline bicarbonate, tight junctions, and rapid epithelial mitosis that replaces itself every three days
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Peptic Ulcers
Erosions of the mucosa of the stomach or duodenum due to HCl
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Helicobacter Pylori
Bacterium that reduces mucosal barriers to acid
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Small Intestine Structure
Food travels from the duodenum to the jejunum, and finally the ileum. Folds allow for better absorption, want the most surface area possible
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Small Intestine Function
Complete digestion of carbs, proteins and fats.
| Absorption of nutrients: rapid due to villi and microvilli
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Duodenum and Jejunum
Absorbs sugars, lipids, amino acids, calcium, and iron
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Ileum
Absorbs biles salts, vitamin B12, water, and electrolytes
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Vlli
Composed of columnar epithelium and goblet cells (which secrete mucus). It has capillaries that absorb monosaccharides and amino acids, and lacteals (lymphatic things...) that absorb fats.
Fats are absorbed in the lacteals (central lymphatic thing...)
Need to replace all this stuff frequently
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Intestinal Crypts
Crypts of lieberkuhn. Contains panted cells and mitotic stem cells (replenish intestinal cells every 4-5 days)
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Microvilli
Brush border, folding of apical surface of each epithelial cell (higher surface area, better absorption)
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Intestinal Enzymes
Brush border enzymes: hydrolyze disaccharides, polypeptides, and other substrates to simple nutrient molecules (literally on the microvilli)
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Disaccharidase
Category of enzymes including sucrase, maltase, and lactase. Helps break sugars down to glucose (and sometimes fructose and galactose)
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Peptidase
Category of enzymes that includes amino peptidase (produces free amino acids, dipeptides and tripeptides) and enterokinase (activates trypsin)
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Phosphatase
Ca/Mg-ATPase (needed for absorption of dietary calcium) and alkaline phosphatase (removes phosphate groups from organic molecules). Both may be regulated by vitamin D
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Interstitial Cells of Cajal
Endogenous pacemaker, causes very slow automatic smooth muscle contractions
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Large Intestine Structure
Through the ileocecal valve (controls what goes in) --> cecum --> ascending colon --> transverse colon --> descending colon --> sigmoid colon --> rectum --> anal canal --> anus
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Large Intestine Function
Absorbs water, electrolytes, vitamin K, and some B vitamins. Produces some vitamin K and B, via microbes, and stores feces.
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Microflora
Resident microbes in large intestine. Mostly anaerobic. They produce vitamin K and some B vitamins, make fatty acids to aid in electrolyte absorption, and outcompete harm bacteria
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Inflammatory Bowel Disease
Can be the result of the disruption of microflora
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Liver Structure
Largest abdominal organ, made up of hepatic plates which are formed by the quickly regenerating hepatocytes. Hepatic plates are separated by capillaries called sinusoids which are very permeable to blood proteins, fat, and cholesterol
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Liver Function
Secretes bile (salts and pigment), detoxification of blood, carbohydrate metabolism, lipid metabolism, protein synthesis
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Hepatic Portal System
Liver's job is to take substances from the blood, that's what hepatic clearance is
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Hepatic Clearance
Ability of the liver to remove substances from blood. A minimum of 25% of cardiac output is needed to maintain this
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Hepatic Artery
Supplies the liver with 20-25% of blood flow
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Hepatic Portal Vein
Supplies the liver with 75-80% of its blood flow from intestines, gallbladder, pancreas, momentum, and spleen
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Hepatic Vein
Vein through which the blood leaves the liver to join regular venous circulation
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Enterohepatic Circulation
Substances that are cleared by the liver, go into the small intestine and then are reabsorbed and returned to the liver.
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Detoxification of blood
Removal of hormones, drugs, and other substances through excretion into bile, phagocytized by Kupffer cells, and being chemically altered by hepatocytes
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Liver and glucose
Basically: glycogenesis, lipogenesis, glycogenolysis, gluconeogenesis, and ketogenesis.
Helps balance glucose by removing it and storing it as glycogen (glycogenesis) or triglycerides (lipogenesis). Also breaks down glycogen (glycogenolysis) and releasing glucose into the blood. Also can make glucose from amino acids (gloconeogenesis) and convert fatty acids into ketones (ketogenesis)
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Gallbladder
Stores and concentrates bile from the liver
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Sphincter of Oddi
Controls the release of bile and pancreatic juice into duodenum
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Pancreas
Endocrine functions: makes insulin and glucagon through the Islets of Langerhans cells
Exocrine functions: Acinar cells make pancreatic juice
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Pancreatic Juice
Made up of bicarbonate and 20 digestive enzymes that break down all four main macro molecules
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Pancreatic Enzymes
Most are zymogens secreted into the lumen of the small intestine.
Trypsinogen (zymogen form of trypsin) is cleaved into the active form by enterokinase. Trypsin then activates other enzymes
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Vagus Nerve
Regulates digestive system. Also part of a conditioned reflex
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Gastrin
Secreted by the stomach. Stimulates parietal cells to secrete HCl, chief cells to secrete pepsinogen
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Secretin
Secreted by the small intestine. Stimulates water and bicarbonate secretion in pancreatic juice
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Cholecystokinin (CCK)
Secreted by the small intestine. Stimulates contraction of the gallbladder, secretion of pancreatic juice enzymes, inhibit gastric motility and secretion
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Gastric inhibitory peptide (GIP)
Secreted by the small intestine. Inhibits gastric motility and secretion. Stimulates secretion of insulin
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Intrinsic GI Regulation
Pacesetter cells
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Extrinsic GI Regulation
HCl and pepsinogen secretion occurs when proteins enter stomach. Initiated and regulated by G cells (gastrin), D cells (somatostatin) and ECL cells (histamine)
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Three Phases of Extrinsic Regulation
Cephalic phase, gastric phase, intestinal phase
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Cephalic Phase of Extrinsic Regulation
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Control by brain via vagus nerves. First 30 minutes of a meal
Stimulates ECL (major response) --> chief cells --> parietal cells
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Gastric Phase of Extrinsic Regulation
Gastric secretion stimulated by stomach distension and chemical nature of chyme
Positive feedback: more proteins broken down, more secretions
Glucose and fats have no effect on this, they are not digested in the stomach
Negative feedback: decrease in pH (more HCl) --> somatostatin released --> inhibits gastrin secretion
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Intestinal Phase of Extrinsic Regulation
Inhibition of gastric activity when chyme enters small intestine (SI). Slows chymes movement into duodenum to give enough time for digestion and absorption.
Duodenum Stretches --> neural reflex that inhibits gastric stimulation via vagus nerve
Presence of fats stimulates the duodenum to make enterogastrone --> inhibits gastric function
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Digestion of Carbohydrates
They are digested in the mouth and small intestine but not the stomach, it is too acidic. They are absorbed through secondary active transport with Na, and facilitated diffusion through GLUT carriers
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Bile
Secreted by the liver, functions in the duodenum where it emulsifies fat, breaking it down to fatty acids and glycerol.
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Absorption of Fats
In SI, breaks fats into bile micelles then transported into villi epithelium. Once in the cell they are regenerated into triglycerides, cholesterol, and phospholipids and combined with proteins to form chylomicrons
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Digestion of Proteins
Begins in stomach (pepsin and HCl), finishes in duodenum and jejunum of the SI (trypsin, chymotrypsin, elastase, carboxypeptidase and the brush border enzyme amino peptidase)
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Very-Low-Density-Lipoproteins (VLDL's)
Apolipoproteins combined with cholesterol and triglycerides to deliver triglycerides to different organs
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Low-Density-Lipoproteins (LDL's)
Apolipoproteins combined with just cholesterol for transport to organs via blood vessels
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High-Density-Lipoproteins (HDL's)
Transport excess cholesterol to the liver (cleans up, pretty much, reducing cholesterol in blood)
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Positive energy balance
Excess calorie intake (regardless of source) = storage of fat
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Negative energy balance
Weight lost when fewer calories consumed than needed
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Essential Amino Acids
lysine, tryptophan, phenylalanine, threonine, valine, methionine, leucine, isoleucine, histidine
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Essential Fatty Acids
Linoleic acid (comes from corn, saturated, omega-6) and alpha-linolenic acid (omega-3)
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Turnover rate
Rate at which a particular molecule is broken down and remade (Proteins: 150g/day and fat: 100g/day)
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Essential nutrients
Can’t be made by body, must be obtained from diet
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Vitamins
Small organic molecules that serve as coenzymes or perform a specific function
Must be obtained in the diet because body can't make them or does so only in small amounts (D, K, B)
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Fat-Soluble Vitamins
A, D, E, K --> can be stored in body, so they can be dangerous/poisonous
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Water-Soluble Vitamins
B's and C's --> can't be stored in body, pee out
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Minerals
Inorganic molecules used as cofactors and in a wide range of processes
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Macronutrients
Na, K, Mg, P, Ca, Cl, needed in large amounts (mg's)
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Other Minerals (trace)
Fe, Zn, Mn, F, Cu, Mo, Cr, Se, I, needed in trace amounts. (micrograms)
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Free radicals
molecules with unpaired electrons. Serve a role in immune response in phagocytes, vasodilation & scar formation
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Reactive oxygen species
Produced in ETC; superoxide radical (O2•), hydroxyl radical (HO•)
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Reactive nitrogen species
nitric oxide radical (NO•)
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Oxidative stress
Too many free radicals leading to cellular damage. Promotes apoptosis, aging-associated degeneration, cancer malignancy, inflammatory diseases, cardiovascular & neurological diseases
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Circulating energy substrates
Fatty acids, glucose, and amino acids in bloodstream
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Adipostat
Mechanisms that defend a set amount of adipose tissue = negative feedback loop
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White fat
Stores energy as triglycerides
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Adipocytes
Secrete hormones that regulate hunger and metabolism.
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Adipokines
Regulatory molecules secreted by adipocytes that affect hunger, metabolism & insulin sensitivity
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Adiponectin
Stimulates muscle cells to use glc and fatty acids
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Leptin
Secreted in proportion to the amount of stored fat
i. Immune response: starving = reduced immune activity; TH cells have leptin receptors
ii. Regulates hunger via feedback to hypothalamus
iii. Regulates reproductive processes via hypothalamus. Low body fat = will not ovulate or menstruate.
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Obesity
Risk factor for cardiovascular disease, diabetes, gallbladder disease, and some cancers
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Childhood obesity
increasing # & size of adipocytes
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Adulthood obesity
increase in size alone
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BMI (weight in kg/height in m2)
19-25 = healthy
26-29 = overweight
over 30 = obese
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Hyperphagia
Overeating, caused by ventromedial hypothalamus lesions
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Hypophagia
Underrating, caused by lateral hypothalamus lesions
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Endorphins and Seratonin
Play a role in suppressing eating
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Norepinephrine
Plays a role in stimulating eating (Rest or digest)
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Melanocyte-stimulating hormone (MSH)
Decreases hunger
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Neuropeptide Y and Agouti-related protein (AgRP)
Increase hunger. Neuropeptide Y does this directly, AgRP inhibits MSH.
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Arcuate nucleus of hypothalamus
Produces hormones involved in hunger
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Ghrelin
Secreted by an empty stomach. Stimulates release of Neuropeptide Y and AgRP. As stomach fills, ghrelin reduces
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Cholecystokinin (CCK)
Levels rise right after a meal, promoting satiety suppressing hunger
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Polypeptide YY (PYY)
Reduces appetite, stimulates MSH
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Leptin cont.
Reduces hunger by inhibiting neuropeptide Y and Agouti-related protein and by stimulating MSH
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Insulin
Reduces hunger indirectly by increasing fat storage which increases leptin production. Main hormone regulating blood glucose levels, working to remove excess by inserting GLUT4 carrier proteins in membrane of target cells (muscle, liver, adipose cells)
Can also inhibit neuropeptide Y
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Beta cells
Secrete insulin (60% of regulation)
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Alpha Cells
Secrete glucagon (25% of regulation)
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Delta Cells
Secrete somatostatin (15% of regulation)
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Diabetes Mellitus
Characterized by chronic high blood glucose
Results from inadequate secretion or action of insulin
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Type I Diabetes (Insulin-Dependent)
AKA juvenile-onset diabetes
Autoimmune disease: beta cells destroyed so no insulin made = insulin injections required
Also marked by abnormally high glucagon secretions
Stimulates glycogenolysis in liver further increase blood glc
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Type II Diabetes (Insulin-Independent)
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AKA mature-onset diabetes
Most common (95%)
Caused by very low target cell sensitivity to insulin = insulin resistance. Higher risk with obesity
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Insulin Sensitivity
Varies from person to person, but exercise increases skeletal muscle sensitivity to insulin and obesity decreases target cell sensitivity to insulin
