Reading...
Play button
Play button
Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
173 Cards in this Set
- Front
- Back
|
________ of monomers occurs in small intestine
|
Absorption
|
|
|
Functions of the GI tract (6)
|
Motility
Secretion Digestion Absorption Storage and Elimination Defensive Barrier |
|
|
Motility is movement of food through GI tract by means of:
|
Ingestion--taking food into mouth
Mastication--chewing food and mixing it with saliva Deglutition--swallowing food Peristalsis--rhythmic wave-like contractions that move food through GI tract (segmentation) |
|
|
(Pancreas) Secretion includes release of ______ and ______ products
|
exocrine(trypsin lipase, amylase, etc..) and endocrine (insulin, glucagon)
|
|
|
Exocrine secretions (into the lumen of the GI tract) include:
|
HCl, H2O, HCO3-, bile, lipase, pepsin, amylase, trypsin, elastase, and histamine
|
|
|
Endocrine includes hormones secreted by the stomach and small intestine (into the bloodstream) to help regulate GI system including:
|
gastrin, secretin, CCK, GIP, GLP-1, guanylin, VIP, and somatostatin
|
|
|
Absorption
|
Is passage of digested end products into blood or lymph
|
|
|
Immune Barrier includes:
|
physical barrier formed by tight junctions between cells of small intestine and cells of the immune system that reside in connective tissue just below epithelium
|
|
|
Digestive System Is composed of __________ and ___________.
GI tract is ~30 ft long*; extends from _____ to ______. *if removed from the body and stretched out – probably closer to half that ____ in the body |
GI tract (alimentary canal) and accessory digestive organs
mouth to anus 15ft |
|
|
Digestive system organs:
Accessory organs: |
Organs include oral cavity, pharynx, esophagus, stomach, and small and large intestine
Accessory organs include teeth, tongue, salivary glands, liver, gallbladder, and pancreas |
|
|
4 Layers of the GI tract:
|
The 4 layers are the mucosa, the submucosa, the muscularis, and the serosa
|
|
|
Mucosa Is the absorptive and secretory layer lining _____ of GI tract
In places is highly _____ with villi to increase absorptive area Contains ____ nodules, mucus-secreting ____ cells, and thin layer of _____. |
lumen
folded lymph goblet muscle |
|
|
Submucosa Is a thick, highly ______ layer of connective tissue where absorbed molecules enter ____ and ______ vessels
Contains glands and nerve plexuses (submucosal plexus) that carry ___ activity to muscularis mucosae of small and large _______. |
vascular
blood and lymphatic ANS intestines |
|
|
Muscularis Is responsible for segmental _______ and peristaltic movement through GI tract
Has an inner circular and outer longitudinal layer of ______ muscle Activity of these layers moves food through tract while pulverizing and mixing it ______ plexus between these layers is major nerve supply to GI tract Includes fibers and ganglia from both ____ and ______ systems |
contractions
smooth Myenteric plexus sympathetic and parasympathetic |
|
|
(Layers of GI tract) Serosa is _______ layer.Serves to bind and protect
Consists of ____ (fibrous, mesh-like) connective tissue covered with a layer of simple squamous epithelium |
outermost
areolar |
|
|
Regulation of GI Tract Parasympathetic effects, arising from ___ and ____ nerves, stimulate motility and secretions of GI tract
Sympathetic activity reduces _____ and _____ activity GI tract contains an intrinsic system that controls its movements--the _____ nervous system GI motility is influenced by paracrine and hormonal signals |
vagus and spinal
peristalsis and secretory enteric |
|
|
Mastication
|
(chewing) mixes food with saliva which contains salivary amylase, an enzyme that catalyzes partial digestion of starch
|
|
|
______ (swallowing) begins as voluntary activity
Oral phase is voluntary and forms a food ____ Pharyngeal and esophageal phases are ________ and cannot be stopped To swallow, _____ is raised so that epiglottis covers entrance to respiratory tract A swallowing center in ______ orchestrates complex pattern of contractions required for swallowing |
Deglutition
bolus involuntary larynx medulla |
|
|
Esophagus connects _____ to stomach
Upper ____ contains skeletal muscle Middle ____ contains mixture of skeletal and smooth Terminal portion contains only _____. Passes through diaphragm via _________ hiatus |
pharynx
third third smooth esophageal |
|
|
________ propels food thru GI tract
= wave-like muscular contractions After food passes into stomach, the _________ ______constricts, preventing reflux |
Peristalsis
gastroesophageal sphincter |
|
|
Stomach is most _______ part of GI tract
Empties into the ________. Functions in: storage of food; initial digestion of proteins; killing bacteria with high acidity; moving soupy food mixture (______) into intestine |
distensible
duodenum chyme |
|
|
Stomach is enclosed by ________ sphincter on top and _____ sphincter on bottom
Is divided into 3 regions: |
gastroesophageal sphincter
pyloric sphincter Fundus Body Antrum |
|
|
Inner surface of stomach is highly folded into _____.
Contractions of stomach churn _____ , mixing it with gastric secretions Eventually these will propel food into ____ intestine |
rugae
chyme small |
|
|
Gastric mucosa has gastric ___ in its folds which are the openings of the gastric _____.
Cells that line the pits deeper in the mucosa, produce ________ secretions |
pits
glands exocrine |
|
|
Gastric glands contain cells that secrete different products that form gastric juice
Goblet cells secrete ______. Parietal cells secrete ____. Chief cells secrete ______. |
mucus
HCl and intrinsic factor (necessary for B12 absorption in intestine) pepsinogen (precursor for pepsin) |
|
|
Other specialized stomach cells:
Enterochromaffin-like cells secrete ______ and ______ G cells secrete ______ D cells secrete ________ |
histamine and serotonin
gastrin somatostatin |
|
|
HCl is produced by ______ cells which pump H+ into _____ via an _____ pump (pH ~1)
Cl- is secreted by _____ diffusion H+ comes from dissociation of _____ Cl- comes from blood side of cell in exchange for _____. |
parietal
lumen H+/ K+ facilitated H2CO3 HCO3- |
|
|
HCl is secreted in response to the hormone ______; and ___ from vagus
These are indirect effects since both stimulate release of ______ which causes parietal cells to secrete HCl HCl converts _______ into pepsin |
gastrin
ACh histamine pepsinogen |
|
|
Both HCL and pepsin can damage lining and produce a peptic _____.
1st line of defense is the adherent layer of ____. = a stable gel of mucus coating the gastric _______. Contains ______ for neutralizing HCL Is a barrier to actions of pepsin Gastric epithelial cells contain tight junctions to prevent HCL and pepsin from penetrating the surface Gastric epithelial cells are replaced every __ days |
ulcer
mucus epithelium bicarbonate 3 |
|
|
Proteins are _____ digested by pepsin
_______ digestion by salivary amylase is inactivated by stomach acidity Alcohol and aspirin are the only commonly ingested substances that are ______ by the stomach |
partially*****
carbohydrate absorbed***** |
|
|
___ ______ are erosions of mucous membranes of stomach or duodenum caused by action of HCl
|
peptic ulcers
|
|
|
In Zollinger-Ellison syndrome, _____ ulcers result from excessive gastric acid in response to high levels of gastrin
_______ ________ infection is associated with ulcers ______ ________ is an inflammation that results in acid damage due to histamine released by inflammation |
duodenal
Helicobacter pylori acute gastritis |
|
|
Small Intestine Is _____ part of GI tract; approximately 3m (~10’) long
Duodenum is 1st 25cm (~10”) after pyloric sphincter _____ is next 2/5 (~4’) of length _____ is last 3/5 (~6’) of length; empties into large intestine |
longest
Jejunum Ileum |
|
|
Absorption of digested food occurs in the ___________.
|
small intestine
|
|
|
Small intestine Surface area increased by _____and _______.
Large folds are _____ _______ Microscopic finger-like projections are ____ Apical hair-like projections are ______ |
foldings and projections
plicae circulares villi microvilli |
|
|
Each villus in the SI is covered with columnar ______ cells interspersed with _____ cells
|
epithelial
goblet |
|
|
Epithelial cells in pits near villi are exfoliated and replaced by mitosis in ____ of _______.
|
crypts of Lieberkuhn
|
|
|
Inside each villus are ________, ________, and _____ _______.
|
lymphocytes, capillaries, and central lacteal
|
|
|
A carpet of hair-like microvilli project from apical surface of each ______ cell
Create a _____ border |
epithelial
brush |
|
|
Attached to microvilli are brush border _____ that are not secreted into lumen
Enzyme active sites are exposed to ____ |
enzymes
chyme |
|
|
2 major types of contractions occur in SI:
|
Peristalsis is weak and slow and occurs mostly because pressure at pyloric end is greater than at distal end
Segmentation is major contractile activity of SI Is contraction of circular smooth muscle to mix chyme (shown in diagram) |
|
|
Intestinal Contractions and Motility Occur automatically via endogenous __________ activity
Contractions are driven by graded depolarizations called ____ _____. |
pacemaker
slow waves |
|
|
Slow waves are produced by non-neuronal/non-muscular cells called ____ ______ of ______.
Have long processes joined to each other and to smooth muscle via ___ junctions Spreads ________ from one cell to next |
interstitial cells of Cajal (ICC)
gap depolarization |
|
|
Large Intestine (LI) or Colon Has no _________ function but can absorb H2O, electrolytes, B and K vitamins, and folic acid
Internal surface has no ____ or crypts and is not very elaborate Contains large population of _____ = 1013 to 1014 ______ _______ of 400 species which produce folic acid and vitamin K and ferment indigestible food to produce fatty acids And reduce ability of pathogenic bacteria to infect LI _______ can negatively affect commensals |
digestive
villi microflora commensal bacteria antibiotics |
|
|
large intestine (colon) extends from _____ valve at end of SI to ____.
Outer surface bulges to form pouches (______) Chyme from SI enters ____, then passes to ______ colon, ______ colon, _______ colon, ______ colon, _____, and ____ canal |
ileocecal to anus
haustra cecum ascending transverse descending sigmoid rectum and anal canal |
|
|
The small intestine (ileum) absorbs most ingested water but the large intestine absorbs ___% of water it receives
Begins with osmotic gradient set up by _____ transport Water follows by osmosis Salt and water reabsorption stimulated by _________. Water follows salt by osmosis LI can also (rarely) secrete H2O by osmosis following active transport of ____ into intestinal lumen After electrolytes and water have been absorbed, waste material passes to _____ , is eliminated as feces. |
90
active aldosterone NaCl rectum |
|
|
Functions of the Liver
|
Detoxification of the blood
Carbohydrate metabolism Lipid metabolism Protein synthesis Production and secretion of bile |
|
|
Hepatic Portal System Food absorbed in SI is delivered 1st to ____
Capillaries in digestive tract drain into the _____ portal vein which carries blood to liver Hepatic vein drains liver Liver also receives blood from the hepatic ____ |
liver
hepatic artery |
|
|
Liver is the _____ internal organ
Hepatocytes form hepatic plates that are 1–2 cells thick Plates are separated by _____ which are fenestrated and permeable even to proteins Contain phagocytic Kupffer cells |
largest
sinusoids |
|
|
Liver Lobules
|
Are functional units (~1 mm diam.) formed by hepatic plates
In middle of each is central vein At edge of each lobule are branches of hepatic portal vein and artery which open into sinusoids |
|
|
Bile is secreted by _______ in bile canaliculi
Empty into bile ducts which flow into hepatic ducts that carry bile away from liver |
hepatocytes
|
|
|
Absorption of digested food (protein, carbs, fats) occurs in SI, mainly in _____ and _______.
Bile salts, vitamin B12, water, and electrolytes are absorbed primarily by the ____. |
duodenum and jejunum
ileum |
|
|
A damaged liver can regenerate itself from mitosis of surviving _______.
|
hepatocytes
|
|
|
In some cases, such as alcohol abuse or viral hepatitis, ________ does not occur
Can lead to liver fibrosis and ultimately cirrhosis |
regeneration
|
|
|
Enterohepatic Circulation
|
Is recirculation of compounds between liver and intestine
Many compounds are released in bile, reabsorbed in SI, and returned to liver to be recycled Liver excretes drug metabolites into bile to pass out in feces |
|
|
Detoxification of the blood (in liver)
|
Phagocytosis by Kupffer cells
Enzymatic and chemical alteration of biologically active compounds Production of urea, uric acid (less toxic than ammonia) Excretion of compounds into bile |
|
|
Carbohydrate Metabolism
|
Conversion of blood glucose to glycogen and fat
Production of glucose from liver glycogen and from other molecules (amino acids, lactic acid) via gluconeogenesis Secretion of glucose into the blood |
|
|
Lipid Metabolism
|
Synthesis of triglycerides and cholesterol
Excretion of cholesterol in bile Production of ketone bodies from fatty acids |
|
|
Protein synthesis
|
Albumin (most abundant protein in blood)
Plasma transport proteins Blood clotting factors (fibrinogen, prothrombin, Factor VIII, Factor IX, etc.) |
|
|
Production and secretion of bile
|
Produced in liver. Stored in gall bladder
Synthesis of bile salts Conjugation and excretion of bilirubin |
|
|
Functions of Bile Essential in digestion and absorption of ___ (also fat-soluble compounds like certain vitamins)
Excretion of _____ (toxic hemoglobin breakdown product) Helps to neutralize acids from stomach Bacteriocidal |
fats
bilirubin |
|
|
Bile Acids Are formed in major breakdown pathway for ________
Are mostly cholic and chenodeoxycholic acids Form bile salts by combining with glycine or taurine Bile salts aggregate as micelles 95% of bile acids are absorbed by ____. |
cholesterol
ileum |
|
|
Pacreas Is located behind _____
Has both endocrine and exocrine functions Endocrine function performed by _________ of ____________. Secretes insulin and glucagon Exocrine secretions include bicarbonate solution and digestive (pro)enzymes These pass in pancreatic duct to ___. Exocrine secretory units are ____. |
stomach
islets of Langerhans SI acini |
|
|
_____ _____: where acinar cells prod. Inactive enzymes stored as zymogen granules which are secreted via ducts into duodenum
|
exocrine acini
|
|
|
Pancreatic Juice Contains?
|
water, bicarbonate, and digestive enzymes
Digestive enzymes include amylase for starch, trypsin for proteins, and lipase for fats Brush border enzymes are also required for complete digestion |
|
|
The Activation of Pancreatic Juice Enzymes Trypsin is activated by ____ ______ enzyme, enterokinase
Trypsin in turn activates other zymogens |
brush border
|
|
|
____ nerve is heavily involved in regulating and coordinating digestive activities
|
Vagus
|
|
|
GI tract is both an endocrine gland and target for action of hormones
Hormones include: |
secretin, gastrin, CCK, and GIP
|
|
|
Gastric motility and secretion occur _______– neural and hormonal effects are superimposed on automatic activity
Extrinsic control of gastric function is divided into _____, _______, and ______ phases. |
automatically
cephalic, gastric, and intestinal phases |
|
|
Cephalic Phase Refers to control by brain of _____ activity
Stimulated by sight, smell, and taste of food Activation of vagus: Stimulates ____ cells to secrete pepsinogen Directly stimulates ___ cells to secrete gastrin Directly stimulates ___ cells to secrete histamine Indirectly stimulates parietal cells to secrete HCl Continues into 1st ___ min of a meal |
vagus
chief G ECL 30 |
|
|
During Gastric Phase ________ of stomach stim. vagus nerve
Vagus nerve stim. acid secretion Amino acids and peptides in stomach lumen stim. _____ secretion Direct stim. of parietal cells Stim. of gastrin secretion; gastrin stim. acid secretion ______ secretion inhibited by when pH of gastric juice falls below 2.5 |
Distention
acid gastrin |
|
|
Short polypeptides and amino acids stimulate ___ cells to secrete gastrin and ____ cells to secrete pepsinogen
|
G
Chief |
|
|
Gastrin stimulates ECL cells to secrete histamine which stimulates parietal cell secretion of HCl
This is a _______ _______ ________: As more HCl and pepsinogen are secreted, more polypeptides and amino acids are released |
positive feedback mechanism
|
|
|
HCl secretion decreases if pH < 2.5; at pH 1 gastrin secretion stops
___ cells stimulate secretion of somatostatin which inhibits _____ secretion |
D
gastrin |
|
|
Intestinal Phase begins when _____ enters the SI and inhibits gastric activity
Arrival of chyme in SI is detected by sensory neurons of _____ This causes a neural reflex that inhibits gastric motility and secretion Fat in chyme stimulates SI to secrete _________--hormones that inhibit gastric motility and secretion __________ (repeat) include somatostatin, GIP, CCK, and GLP-1 GIP and GLP-1 stimulate _______ secretion in anticipation of glucose entering blood from digestion |
chyme
vagus enterogasterones insulin |
|
|
Gastroileal reflex refers to
|
increased motility of ileum and movement of chyme thru ileocecal sphincter in response to increased gastric activity
|
|
|
Ileogastric reflex decreases gastric motility in response to distension of ____.
|
ileum
|
|
|
Intestino-intestinal reflex causes _____ of rest of intestine when any part is overdistended
|
relaxation
|
|
|
Secretion of pancreatic juice is stimulated by _____ and ______.
Secretin is secreted in response to duodenal pH < 4.5 Stimulates release of HCO3- into ___ by pancreas CCK is secreted in response to fat and protein content of ____ in duodenum Stimulates production and release of pancreatic enzymes into ___ |
secretin and CCK (cholecystokinin)
SI chyme SI |
|
|
(Pancreas) Salivary amylase ____ starch digestion
Pancreatic amylase converts starch to __________. ___________ hydrolyzed by SI ___ _____ enzymes |
begins
Oligosaccharides brush border |
|
|
Digestion and Absorption of Protein Begins in stomach when _____ digests proteins to form polypeptides
In SI, the pancreatic juice enzymes endopeptidases (trypsin, chymotrypsin, elastase) cleave peptide bonds in interior of polypeptides SI exopeptidases (carboxypeptidase -pancreatic juice and aminopeptidase- brush border enzyme) cleave peptide bonds from ends of polypeptides Results in free amino acids, dipeptides, and tripeptides Free amino acids absorbed by cotransport with Na+ into ____ cells and secreted into blood caps. Di- and tripeptides carried into ______ cell where hydrolyzed into free amino acids then secreted |
pepsin
epitheleal epitheleal |
|
|
Protein digestion in SI occur mainly in?
|
(mainly duodenum, jejunum)
|
|
|
Arrival of lipids in duodenum causes secretion of ___.
____ is emulsified by bile salt micelles Forms tiny droplets of fat dissolved in bile salt micelles Greatly increases surface area for fat digestion |
bile
Fat |
|
|
Digestion of Triglycerides Pancreatic ____ hydrolyzes triglycerides to free fatty acids and monoglycerides
Phospholipase __ breaks down phospholipids into fatty acids and lysolecithin |
lipase
A |
|
|
Products of __ digestion dissolve in micelles forming mixed micelles which move to brush border
|
fat
|
|
|
Free fatty acids, monoglycerides, and lysolecithin leave micelles and enter _________ cells
Inside ________ cells, they are resynthesized into triglycerides and phospholipids |
epithelial
|
|
|
Triglycerides and phospholipids combine with a protein to form small particles called _________
Which are secreted into central lacteals of SI villi |
chylomicrons
|
|
|
In blood, chylomicrons combine with __________
Which allows them to bind to receptors on _________ in muscle and fat |
apolipoprotein
capillaries |
|
|
When bound to receptors on capillaries endothelial lipoprotein lipase hydrolyzes the _______ to free fatty acids and glycerol for energy use by muscle and storage in fat
Cholesterol-containing remnants are taken up by ____ |
triglycerides
liver |
|
|
ATP derived from glucose, fatty acids, ketones, amino acids, and others
Energy of food is commonly measured in kilocalories (1 kcal = 1000 calories) Carbohydrates and proteins yield 4kcal/gm; fats-9kcal/gm |
remember fat has more energy stored
|
|
|
Metabolic rate (MR)
|
is total rate of body metabolism
Rate of O2 consumption Rate of heat production by body |
|
|
Basal metabolic rate (BMR)
|
is MR of awake relaxed person 12–14 hrs after eating and at a comfortable temperature
BMR depends on age, sex, body surface area, activity level, and strongly influenced by thyroid hormone levels hyper-thyroids have high BMR hypo-thyroids have low BMR |
|
|
Anabolic reactions ________ DNA and RNA, proteins, fats, and carbohydrates
This must occur constantly to replace molecules that are hydrolyzed in catabolic reactions |
synthesize
|
|
|
9 essential amino acids must be supplied in diet because
|
can't be synthesized
|
|
|
Average turnover for fats is ____g/day
Little is required in diet because can be synthesized from Carbs |
100 g/day
|
|
|
2 essential fatty acids must be supplied in diet
|
linoleic acid (corn oil – omega-6)
linolenic (canola oil – omega-3) (Other omega-3’s in fish oil – not essential but protective against cardiovascular disease) |
|
|
Vitamins Are small organic molecules that serve as ________ in metabolism or have highly specific functions
Must be obtained in diet because body does not produce them, or does so in insufficient amounts Can be placed in 2 classes |
coenzymes
Fat-solubles include A, D, E, and K Water-solubles include B1, B2, B3, B6, B12, pantothenic acid, biotin, folic acid, and vitamin C Serve as coenzymes in metabolism |
|
|
Vitamin deficiency diseases
A, B1, B2, B6, B12, Biotin, Vitamin C, Vitamin D, Vitamin E, Folate, Vitamin K, Niacin (B3), Pantothenic acid |
A – night blindness, dry skin
B1 – (beriberi, neuritis) nervous system ailment with cardiovascular and gastrointestinal complications B2 – (glossitis) inflammation of the tongue – swells up and turns dark red (cheilosis) inflammation at corner of mouth –cracks, splits B6 – convulsions B12 – pernicious anemia(happens w/out intrinsic factor in stomach) Biotin – dermatitis Vitamin C – (scurvy) collagen breakdown in skin – spots, bleeding from gums, teeth fall out, affects all mucous membranes Vitamin D – (rickets, osteomalacia) softening of bones, fractures, malformations Vitamin E – muscular dystrophy (non-hereditary) – progressive muscle weakness Folate – (sprue) small intestine – diarrhea, weakness, impaired absorption. Also anemia, problems in embryonic development (spina bifida) Vitamin K – bleeding Niacin, B3 – (pellagra) 4Ds – dermatitis, diarrhea, dementia, death Pantothenic acid – dermatitis, enteritis, adrenal insufficiency |
|
|
Minerals are needed as ______ for specific enzymes and other critical functions
Sodium, potassium, magnesium, calcium, phosphate, and chloride are needed daily in relatively large amounts (around a ____) Iron, zinc, manganese, fluorine, copper, molybdenum, chromium, and selenium are trace elements required in smaller amounts/day (_______, _______) |
cofactors
grams milligrams, micrograms |
|
|
Free Radicals are highly reactive and oxidize or reduce other atoms
Because they have an _____ _____in their outer orbital The major free radicals are reactive _______ or reactive ________ species Because contain oxygen or nitrogen with unpaired electron Include NO radical, superoxide radical, and hydroxyl radical These are not a dietary _________. Result of making ______. |
unpaired electron
oxygen; nitrogen requirement ATP |
|
|
Free Radicals serve important physiological functions. (3)
|
Help to destroy bacteria
Can produce vasodilation Can stimulate cell proliferation |
|
|
Free radicals in excess can exert ______ _____contributing to disease states
Can damage lipids, proteins, and DNA Promote apoptosis, aging, inflammatory disease, degenerative, and other diseases and malignant growth Underlying cause is widespread production of ______ radicals by mitochondria (as a by-product of respiration - making ATP) |
oxidative stress
superoxide |
|
|
Enzymes that neutralize free radicals include
|
superoxide dismutase (SOD), catalase, and glutathione peroxidase
|
|
|
Nonenzymes that react with free radicals by picking up unpaired electrons include
|
glutathione, vitamin C, and vitamin E
|
|
|
Ketone bodies? (3)
|
Acetone, Acetoacetic Acid, Beta-hydroxybutyric acid
|
|
|
Body appears to have _____ ______ _______ (an adipostat) to defend maintenance of a certain amount of adipose tissue
|
negative feedback loops
|
|
|
Adipose cells (adipocytes) store and release fat under ______ control
And release their own hormone(s) to influence metabolism |
hormonal
|
|
|
Development of Adipose Tissue Number of _________ increases greatly after birth. Due to mitosis and differentiation of ________ into adipocytes
Differentiation promoted by high levels of fatty acids |
adipocytes
preadipocytes |
|
|
Adipocytes secrete regulatory hormones called ________.
Regulate hunger, metabolism, and insulin sensitivity e.g., cause muscle to become more or less responsive to _____ Include adiponectin, leptin, resistin, TNF, and retinol BP4 |
adipokines
insulin leptin (remember in particular) |
|
|
The adipocyte hormones TNF, resistin, retinol BP4, and leptin are increased in obesity and Type __ diabetes
|
II
|
|
|
Leptin signals the __________ on how much fat is stored, thereby regulating hunger and food intake
Example of? |
hypothalamus
negative feedback loop |
|
|
__________ is decreased in obesity and Type II diabetes
has an insulin-sensitizing, antidiabetic effect |
Adiponectin
|
|
|
Helper T cells have _____ receptors
Thus, low _____ can lead to diminished immune function ______ may play role in timing of puberty and in the amenorrhea of underweight women |
leptin
|
|
|
BMI =
healthy? |
w÷h^2
b/t 19-25 |
|
|
calorie is defined as
|
The amount of energy required to raise the temperature of one gram of water by one degree centigrade.
|
|
|
some benefits of linoleic acic
|
Anticancer effects
Helps cystic fibrosis patients Helps diabetes patient |
|
|
Monounsaturated fat also means
|
trans fat
|
|
|
linolenic acid deficiency leads to
|
Skin problems (scaly rash, eczema)
Alopecia (hair loss) Neurological problems ADD, depression, mental illness Thrombocytopenia Growth retardation Vision problems |
|
|
Regulation of hunger is at least partially controlled by ________.
Lesions in ventromedial area produce hyperphagia and obesity in animals Lesions in lateral area produce hypophagia |
hypothalamus
|
|
|
Regulation of hunger Involves a number of ____________. Including:
|
neurotransmitters
endorphins (promote overeating), norepinephine (promotes overeating), serotonin (suppresses overeating) Very successful diet pills Redux and fen-phen worked by elevating brain serotonin (Now banned because of heart valve side effects) |
|
|
Regulation of Hunger involves arcuate nucleus of hypothalamus, which responds to both neural and hormonal signals
Its neurons send axons to other parts of the brain where they release specific neurotransmitters One type of neuron produces ____ which suppresses hunger by acting on its receptor Obesity is associated with mutations in this receptor, leading to increased hunger and decreased energy expenditure Another type of neuron produces ___________ __ and _______ _______ which increase hunger b/c arp inhibits MSH Know This Slide****** |
MSH
neuropeptide Y agouti-related peptide Know this slide****** |
|
|
Regulation of hunger involves _______ hormones secreted by the stomach and SI
|
polypeptide
|
|
|
______ stimulates hunger via its effect in the arcuate nucleus
Secreted by stomach at high levels when stomach is empty and low levels when full |
Ghrelin
|
|
|
CCK from ____ promotes satiety
Levels rise during and immediately after a meal |
SI
|
|
|
Ghrelin and CCK regulate hunger on?
|
short-term, meal-to-meal basis
|
|
|
____ is secreted by SI in proportion to caloric content of food
Decreases hunger by acting in arcuate to decrease neuropeptide Y and stimulate ____ Seems to serve intermediate level of control because injections reduce appetite for 12 hrs |
PYY
MSH |
|
|
(Regulation of Hunger) Is influenced by ____--a satiety factor secreted by adipocytes and involved in long-term regulation
Secretion increases as stored fat increases Signals body's level of adiposity Acts in arcuate to suppress Neuropep Y and agouti-related peptide; and stimulate ____ (suppress hunger) |
leptin
MSH |
|
|
Insulin may play role in satiety
Suppresses _______ __ |
Neuropep Y
|
|
|
Overall Calorie Expenditure of Body has three components:
|
Number of calories used at the BMR make up 60% of total
Number used in response to temperature changes and during digestion/absorption (adaptive thermogenesis) NORMALLY make-up 10% of total Starvation can lower MR 40%; eating raises MR 25-40% (thermic effect of food) Number used during physical activity depends on type and intensity |
|
|
_________ state is 4 hr period after eating
Energy substrates from digestion are used and deposited in storage forms (anabolism) |
Absorptive
|
|
|
__________ or fasting state follows absorptive state
Energy is withdrawn from storage (catabolism) |
Postabsorptive
|
|
|
Balance between anabolism and catabolism depends on levels of
|
insulin, glucagon, GH, thyroxine, and others
|
|
|
Pancreatic Islets of Langerhans Contain 2 cell types involved in energy homeostasis:
|
ALPHA cells secrete glucagon when glucose levels are low
Which causes increased glucose by stimulating glycogenolysis in liver BETA cells secrete insulin when glucose levels are high Which reduces blood glucose by promoting its uptake by tissues |
|
|
Normal fasting glucose level is
Insulin and glucagon normally prevent levels from rising above ____ mg/dl after meals or falling below ___mg/dl between meals |
100 mg/dl
170; 50 |
|
|
(Insulin) Overall effect is to promote _______
Promotes storage of digestion products Inhibits breakdown of fat and protein Inhibits secretion of glucagon Stimulates insertion of _____ transporters in cell membrane of skeletal muscle, liver, and fat Glucose is transported by facilitated diffusion |
anabolism
GLUT4 |
|
|
A rise in plasma glucose acts on beta-cells of islets where it leads to opening of K+ channels producing depolarization
Depolarization opens voltage-gated Ca++ channels promoting exocytosis of vesicles containing insulin A rise in plasma glucose thus leads to ____ in insulin secretion At the same time, insulin inhibits release of glucagon from alpha-cells of islets |
rise
|
|
|
Maintains blood glucose concentration above 50mg/dl
Stimulates glycogenolysis in liver ________ stimulates gluconeogenesis, lipolysis, and ketogenesis Skeletal muscle, heart, liver, and kidneys use fatty acids for energy |
Glucagon
|
|
|
____ innervates islets
__________ division is activated during meals and stimulates both GI function and secretion of insulin Sympathetic division _____ insulin secretion and _______ glucagon secretion Glucagon and epinephrine work together to produse a stress ________ when the sympathoadrenal system is activated |
ANS
Parasympathetic inhibits; stimulates hyperglycemia |
|
|
Insulin levels increase more after glucose _____ than after intravenous glucose infusion
GIP (glucose-dependent insulinotropic polypeptide) and GLP-1 (glucagon-like* polypeptide) from SI are powerful _______ of insulin secretion |
ingestion
stimulators |
|
|
Diabetes Mellitus is characterized by chronic high blood glucose levels (_________)
|
hyperglycemia
|
|
|
Type I (insulin ______ or IDDM) is due to insufficient insulin secretion
~5% of diabetics are this type |
dependent
|
|
|
Type II (insulin __________ or NIDDM) is due to lack of effect of insulin
~95% of diabetics are this type |
independent
|
|
|
In Type I Diabetes β cells of islets are progressively destroyed by autoimmune attack by killer __ ______________.
|
T lymphocytes
|
|
|
In Type I Diabetes _______ is unable to enter resting muscle or adipose cells
Rate of fat synthesis lags behind rate of lipolysis Fatty acids are converted to ketone bodies, producing __________. Increased _______ levels stimulate glycogenolysis in liver |
Glucose
ketoacidosis glucagon |
|
|
Type II Diabetes is ____ to develop.
|
slow
|
|
|
____________ Has multigene inheritance pattern
Genetic tendency is increased by obesity Involves insulin resistance Usually accompanied by normal-to-high insulin levels Is not usually accompanied by ketoacidosis Treatable by exercise and diet Exercise increases insertion of GLUT4s into skeletal muscle |
Type II diabetes
|
|
|
Oral Glucose Tolerance Test
|
Measures response to drinking a glucose solution
Assesses ability of β cells to secrete insulin and insulin's ability to lower blood glucose In non-diabetics, glucose levels return to normal within 2 hrs |
|
|
_________ __________ is oversecretion of insulin due to an exaggerated response of cells to a rise in glucose
Occurs in people who are genetically predisposed to type II diabetes Symptoms include tremors, hunger, weakness, blurred vision, and confusion |
Reactive hypoglycemia
|
|
|
Serious consequences of diabetes
|
kidney failure, stroke/ heart disease, limb amputation, blindness
|
|
|
Anabolic effects of insulin are antagonized by hormones of adrenals:
|
(epinephrine and cortisol), thyroid (thyroxine), and anterior pituitary (ACTH, growth hormone) on carbohydrate and lipid metabolism
|
|
|
Insulin, thyroxine, and GH can act ________ to stimulate _______ synthesis
|
synergistically
protein |
|
|
____ serves as a 2nd messenger in the actions of epi and glucagon on liver and adipose tissue metabolism.
|
cAMP
|
|
|
Cortisol is secreted in response to ______,
Which is often released in response to stress, including fasting and exercise Where it supports effects of _____. Promotes lipolysis, ketogenesis, and protein breakdown Protein breakdown increases amino acid levels for use in gluconeogenesis in liver All of these help to compensate for a state of prolonged fasting or exercise |
ACTH
glucagon |
|
|
Thyroid secretes mostly tetraiodothyronine (_________) and a little triiodothyronine (T3) in response to TSH
Active form is T3 __ Is converted to T3 in target cells by deiodination Sets ____ by regulating cell respiration Is necessary for growth and development, especially of CNS Increases metabolic heat (calorigenic effect) Is essential for cold adaptation |
thyroxine
T4 BMR |
|
|
Growth Hormone Secretion is from the _____ _______. It is stimulated by ____ and inhibited by ______ from hypothalamus.
|
anterior pituitary
GHRH somatostatin |
|
|
GH secretion Follows a circadian pattern--is _____ during sleep and ______ during waking hours
Stimulates growth in children and adolescents Has important metabolic effects in adults Is stimulated by increased blood amino acids and decreased blood glucose Is increased during fasting Stimulates protein synthesis, fat breakdown, and decreases glucose use by most tissues |
greater ; lower
|
|
|
Insulin-like Growth Factors (IGFs) Are similar to ________; produced by many tissues
Are called _______ because mediate many of GH's effects Liver produces and secretes _____ in response to GH IGF-1 in turn stimulates cell division and growth of cartilage Do not mediate effects of GH on lipolysis and glucose sparing |
pro-insulin
somatomedins IGF-1 |
|
|
Growth of skeleton occurs first as growth of _______ at epiphyseal discs of long bones which then become converted to bone
Mediated by IGF-1 and 2 which stimulate ________ to divide and secrete more cartilaginous matrix Growth stops when epiphyseal discs are ossified |
cartilage
chondrocytes |
|
|
Gigantism
|
produced by excess GH secretion in children
|
|
|
Dwarfism
|
caused by inadequate secretion of GH during childhood
|
|
|
Excess GH secretion in adults, after epiphyseal discs are ossified, results in _______.
There is no increase in height However soft tissue still grows Causing elongation of jaw, deformities in hands, feet, and bones of face |
acromegaly
|
|
|
Essential in all cells and tissues, not just bones
Specific roles in the mechanisms of nerve transmission, muscle contraction, blood clotting, others Normal extracellular concentration ~.001 M Cytoplasmic concentration ~.0000001 M |
Calcium!!
|
|
|
Parathyroid hormone, 1,25-dihydroxyVit D, and calcitonin control ____ and _____ levels and activities…
through their effects on: bone formation and reabsorption, intestinal absorption, and urinary excretion |
Ca2+ and PO43- levels and activities…
|
|
|
Skeleton is a storage reservoir for ______ and ______
Bone is hardened with calcium phosphate crystals (___________) Osteoblasts make bone by 1st secreting a matrix of collagen which becomes hardened by deposition of hydroxyapatite |
calcium and phosphate
hydroxyapatite |
|
|
Formation and resorption of bone occur constantly at rates determined by relative activities of ______ and _______.
|
osteoblasts and osteoclasts
|
|
|
During skeletal growth phase, activity of _______ predominates
|
osteoblasts
|
|
|
During osteoporosis, activity of ________ predominates
|
osteoclasts
|
|
|
In the Reabsorption of Bone by Osteoclasts: _________ first demineralize bone by dissolution of calcium phosphate from the matrix due to acid secretion
Next, ________ is digested by the secretion of the enzyme cathepsin K from the osteoclast |
Osteoclasts
collagen |
|
|
Secreted by parathyroid glands
Is most important hormone in control of Ca2+ levels Release is stimulated by low blood Ca2+ levels Stimulates osteoclasts to reabsorb bone Stimulates kidneys to reabsorb Ca2+ from filtrate, and inhibits reabsorption of P043- Promotes formation of 1,25 Vit D3 Many cancers secrete a hormone called PTH-related protein that interacts with PTH receptors producing hypercalcemia |
Parathyroid hormone
|
|
|
Secreted by C cells of thyroid gland
Opposes the effects of PTH and 1,25 Vit D3 to regulate blood Ca2+ levels Stimulated by increased plasma Ca2+ Inhibits activity of osteoclasts Stimulates urinary excretion of Ca2+ and P043- by inhibiting reabsorption Physiological significance in adults is not understood Pharmacological action as a drug inhibits resorption of bone---helpful in people with stress fractures due to osteoporosis |
Calcitonin!!
|
|
|
1,25 dihydroxyvitamin D3 Directly _______ intestinal absorption of Ca2+ and PO43-
Stimulates bone reabsorption by promoting formation of ______ Stimulates kidney to reabsorb Ca2+ and PO43 Simultaneously raising Ca2+ and PO43- results in increased tendency of these to precipitate as hydroxyapatite Production is stimulated by ___ Inadequate Vitamin __in diet causes bone softening - osteomalacia (in adults) and rickets (in children) |
stimulates
osteoclasts PTH D |
|
|
Production of 1,25 dihydroxyvitamin D3 Begins in skin when a ________ derivative is converted to Vit D3 by sunlight
|
cholesterol
|
|
|
Estrogen is necessary for?
Excessive thyroid hormone predisposes to ________. |
proper bone mineralization and for prevention of osteoporosis
osteoporosis |
