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87 Cards in this Set

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  • Back
The breakdown of polymers into their building blocks
What are the two functions of the digestive system
To digest foodstuffs and to protect against disease
What is the function of the GI tract
Digestive tract, gastrointestinal tract, alimentary canal,gut. Digestion takes place in it from mouth to anus. Derrived from the blastopore. The lumen(inside) is considered the outside of the body
Diagram a GI Tract Layer
lumen, epithelial lining, mucosa, submucosa(large), circular smooth muscle, longitudinal smooth muscle.
What is the function of the GI epithelium
Same type of cells that line the surface of our body and inner surface of respitory tract. Apical surface inside, tight junctions, Basolateral side is on the outside of the lumen. Creates barrier, responsible for secretion.
What accounts for GI motility
Automaticity(contraction not due to outside sources)

Functional syncytium=Spread of action potential to different cells

Enteric nervous system

Hormonal input

Parasympathetic nervous system-stimulates.
Sympathetic inhibits
Explain peristalsis
Circular smooth muscle contracts which doesnt let food go backwards. Longitudinal muscle pushes food down tract. Food called bolus
What is the difference between secretion and excretion
Secretion is the release of useful substances by a cell.
Excretion=disposal of waste
What are the two types of secretions
Exocrine= glands that secrete their products(enzymes etc) into ducts which drain into the GI

Endocrine: ductless glands that secrete hormones into the bloodstream
What are acinar cells
exocrine glands that secrete their products into the gi lumen through ducts.
What organs function as exocrine glands in the GI system
liver, gallbladder, pancreas(acinar cells), Also specialized epithelial cells. (gastric enzyme-stomach) Goblet cells(mucus for protection). Water excretion
What organs/cells perform endocrine secretion into the GI system
the islets of Langerhans of the pancreas secrete endocrine products into capilaries that effect the GI. Also cells of the wall of the gut.
What are the accessory organs of the GI system
Liver, gallbladder, pancreas
What are the mouths functions
Fragmentation(mastication) or chewing

Lubrication: salivia

Digestion: Saliviary amylase(hydrolyze starch-disaccharides) Also lysosome(innate immunity)
What is the function of the pharynx
To differentiate air and food/liquid. The epiglotis directs this flow.
What is the function of the Esophagus
To move food down to the stomach. Upper and lower sphincters. Upper regulates food movement. Lower prevents stomach acid from going up.
What are the three main functions of the stomach
partial food digestion, regulates food release into small intestine, Destructs microorganisms
How is the stomach kept at pH 2.0
Secretion of HCl by parietal cells in the gastric mucosa. Destruction of microorganisms, Hydrolysis of proteins, pepsinogen to pepsin
Pepsin details
Secreted by chief cells, zymogen activated by acidic autocleavage
Stomach motility
Mixes up gastric fluids/food into chyme
Roll of stomach sphincters
lower esophagal; prevents chyme from going up.

pyloric shincter prevents food from entering duodenum. Inhibited from opening by full or acidic duodenum. Cholecystokinin(hormone) inhibits opening.
Hormone secreted by G cells of Stomach cell wall. Stimulates acid/pepsin secretion. Histamine=cofactor. Stimulated by parasympathetic or high food in stomach
What are the three sections of the small intestine in order from the stomach. Where is digestion completed
duodenum, jejunum, ileum.
Completed in the duodenum and jejunum
How does the small intestine obtain a large surface area
Length, Villi(macroscopic projections into the lumen), Microvilli(microscopic folds in epithelial cells). Lumenal surface=brush border.
What are the important structures in the Villi
Capillaries:absorb dietary monosacharides/AA's-hepatic portal vein-liver.

Lacteals: lymphatic vessels which absorb dietary fats.--thoratic ducts--blood stream

Peyers Patches: Contain lymphocytes and are dotted around the villi.
What is the key feature of the Duobenum
It has two ducts

Pancreatic duct: exocrine pancreatic secreations(bicarbonate/digestive enzymes)
Commmon bile Duct: delivers bile:green fluid that contains acids from cholesterol derivitaves stored in the gallbladder.
Helps in excretion of wastes by the liver and digestion of fats.

Both enter from sphincerter of ODDI
What are the functions of the intestinal Duodenal enzymes
Secreted into the Intestin or brush border by epithelial cells. Some are zymogen cleavers and others break down peptides/carbs to monomolecules
What are the duodenal hormones and their functions
Cholecystokinin(CCK): in response to fats epithelial cells secrete this to stimulate gallbladder release of bile. Decrease gastric mobility as well.

Secretin: in response to low ph this hormone causes the pancreas to release basic buffer.

Enterogastrone: decreases stomach emptying
Jejunum and Ileum functions
special absorption of molecules and the valve at the end of the ileum(ilecoecal valve) seperates the ileum from the cecum(large intestine)
Facultative vs obligate anerobes
Facultative can use oxygen or can proceed through fermentation.

Obligate: die in oxygenated environment
What is the function of the colon
The colon stores and forms feces, and absorbs water and minerals.
Water: appendix(lymphatic tissue) of cecum finger like
2 anal sphincters one smooth(internal) autonomically controlled. second is skeletal muscle and is controled by the voluntary system.
What are the GI accesory organs
pancrease, gallbladder, liver
What are the functions of the Exocrine Pancreas
Digestive enzymes such as pancreatic amylase, Pancreatic lipase, Nuclease, Proteases(zymogens(inogen/pro)
How is the exocrine pancreas controlled
CCK- secreated into the blood stream causes pancteatinc enzyme release

Secretin- water/bicarb secretion

Sympathetic(fight\flight)slows pancreatic secretion
Parasympathetic= increases
What are the functions of the endocrine pancreas
Islets of Langerhans(three types of cells)
Glucagon: secreated by a-cells in response to low blood sugar(mobilizes stored fuels)

Insulin; B cells-in response to elevated blood sugar- causes energy storage

Somatostatin: Gamma cells: inhibits digeestive processes
What hormones can increase blood glucose
cortisol, epinephrine, glucagon
What hormones lower blood glucose
What is the exocrine funtion of the liver
It secretes bile
What is the function of the gallbladder
It stores bile and releases it into the small intestine. Release in response to cck
What are teh processing functions of the liver
all gut blood flows to it from the hepatic portal vein and liver stores sugar, makes proteins, reders toxins harmless, modifies waste, and degregates old heme units.
Diagram the path of Carbohydrates
Mouth(saliva), Bolus(touge,cheeks), Esophogus relaxes(upper sphincter--Stomach(acod destroys bacteria), hydrolysis, churning(acidic Chyme formation), duodenum-pancreatic amylase(disacharides), Brush border(monosacharides),active transport across lumen(Na+/Glucose cotransporter, Epithelial(uniport, diffusion),Capilaries, bloodstream, hepatic vein.
What happens to the blood after a high sugar meal
Blood sugar rises pancreatic b cells release insulin
Diagram the uptake of proteins
Mouth(saliva no digestion of proteins), bolus, stomach(kills micros, breaks peptide bonds). Pepsin breaks peptides, Chyme released to duodenum, CCK, Secretin secreted, Pancrease secretes bicarb/digestive enzymes, Brush border peptidases, Secondary active transport across lumen, to liver
Diagram Fat digestion
Mouth,stomach, Duodenum, CCK released into blood stream, Pancrease--enymes from sphincter of ODDi, gullbladder---bile(emulsification-accesible to enzymes), Lipase, Simple diffusion across lumen, in epithelial form chylomicrons, lymphatic capilaries, thoratic duct, plasma, lipoproteinlipase, adipocytes.
What is the difference between fat and water soluable vitamins
Fat soluable vitamins are digested with bile and stored in fat. Water soluable excretid in urine by kidneys.
Name the Fat soluble vitamins
What are the excretory functions of the liver.
Excretes many wastes by modifying them and releasing them into bile. (big waste that cant be filtered by kidney)Old heme units. Synthesizes urea(AA breakdown)
What are is the excretory function of the colon
Large intestine. Processes things destined for excretion but also excretes excess ions(NA, Cl, Ca) into feces
What are the excretory functions of the skin
Excretes sweat(urea, ions, water). Primarily controlled by sympathetic nervous system and temperature control. Excretion is secondary
What is the excretory role of the Kidneys
Excretes hydrophilic waste
Maintenance of constant solute/pH.
Maintains proper fluid volume for proper cardiac output and blood pressure
What part of the kidney is responsible for filtration and how is it regulated
The glomerulus and it is regulated by flitration pressure(determined by blood pressure)
What part of the kidney is responsible for selective reabsorption and how is it regulated
proximal tubule. It is not regulated. Always the same
What part of the kidney is responsible for urine concentration and how is it regulated
Distal nepheron. ADH(volume), aldosterone(serum Na+)
What part of the Kidney is responsible for pH regulation and how is it regulated
Mosth of the nepheron. Automatically regulated by carbonic anhydrase.
How does blood enter and exit the kidney
Through the renal artery from the abdominal aorta. Through the rela vein.
What is the path of urine
Urine goes through the kidney- ureter- bladder(surrounded by smooth muscle) -urethra.
Basic kidney anatomy
outer cortex/inner medula
Medullary pyramids
striations in the medula
Collecting Ducts at end of pyramids.
where urine leaves the medula at tip of pyramid
a space in which urine empties from the papilae.
Renal pelvis
converging point of calyces where urine collects and enters the ureter.
What is the functional unit of the kidney and what are its two components
Renal tuble:recieves filtrate at one end and empties into the collecting ducts

Blood vessles that carry arterial blood toward the tubule and filtered blood away from the renal tubule
Describe the process of blood filtration in detail.
Blood flows from the renal artery to the afferent arteriole. Arteriole branches into capilary balls called glomerulus. Blood is constricted from flowing to the efferent arteriole. Fluid leaks out of blood into glomerular basement membrane into the Bowmans capsule.
Describe Selective Reabsorption as it pertains to the kidney
Most of the filtrate (water/sugar/amino acids) must be selectively reabsorbed by active transport in the proximal convoluted tube(near Bowmans Capsule). Most water follows the flow of solutes back into the peritubular capillaries which drain into the renal vein. Selective but not regulated
Where in the kidney is the osmotic pressure and urine volume determined what two hormones are involved
in the distal portion of the nepheron. Anti Diuretic hormone(ADH) and Aldosterone.
What does ADH do in the kidney and where is it produced.
ADH or vasopressin is produced in the posterior pituitary. It increases water absorption in the distal nepheron by making the membrane permeable to water. Renal medulla has high osmolarity so water tends to leak out of the nepheron
What is diuresis
Under dehydration conditions, the loss of water through urine. Stopped by the release of vasopressin.
What are the effects of large liquid intake or alcohol on the kidney
large h20 or alcohol inhibit the realeas of ADH from the posterior pituitary gland.
What are the effects of aldosterone on the kidney and where is it released from
Aldosterone is released from the adrenal cortex. In response to low blood pressure it is released and causes an increased reabsorption of Na+ in the distal nepheron. This increases plasma osmolarity and water retiontion/thirst. This increases blood pressure
What inhibits the release of aldosterone.
High salt intake/high blood pressure.
What is the flow of urine through the nepheron?
Afferent arteriole,Glomerural(bowmans) capsule, Proximal convoluted tube,All in cortex,
Decending loop of Henle(thin walled squamos cells)(Medula), Acending Loop of henle (thick wall cubiodal cells)(cortex), Distal convoluted tube, Coillecting Duct. Calyces.
What takes place in the proximal convoluted tube
Reabsorbtion of most filtered water and ions, reaborption of glucos and amino acids by secondary active transport
What takes place in the decending loop of henle
Water exits tuble causing filtrate to be more concentrated. Thin cells
What takes place at the vasa recta and peritublar capillaries
Reclamation of absorbed substances
IS the inner medulla hypertonic or hypotonic to the urine in the loop of henle
Hypertonic to drive water reabsorption
What takes place at the distal convoluted tube
Reabsorption of water and urea in response to ADH. Na+ is reabsorbed in response to aldosterone.
What takes place at the ascending loop of henle
Active transport of Cl- out of filtrate with passive movement of Na+
caises dilution of tubular fluid and increased osmolarity of medula
What takes place at the collecting duct
reabsorbtion of water and urea in response to adh. Na+ absorbtion due to aldosterone
What is ment by countercurrent multiplier and where does this occur
The ascending and decending limbs of the loop of henle are in opposite directions and have different permeabilities. Decending permeable to water but not ions(concentration of fluid) accending transports salt out sucks water out in other areas in response to ADH. Alows concentration of urine
What are is the roll of the vasa recta
To suck off any water in the decending loop of henle.
Describe how renal tissue aids in blood pressure regulation
the juxtaglomerular apparatus(contact point between afferent arteriole and distal tubule. JG cells release renin in response to decreased bp. Makes angiotensin II and causes vasoconstriction and release of aldosterone. Macula densa cells (distal tubule) cause stimulation of JG cells in response to low filtrate osmolarity
Describe Renal pH regulation
When plasma pH is to high kidney excretes HC03- into the urine. Too low excretes H+ into urine. Carbonic Anhydrase is involved and is in epithelial cells of nepheron. Slow regulation lungs faster
What is the target and effect of aldosterone
Adrenal cortex. sodium reabsorption increased. potasium excretion increased because of increased synthesis of basolateral Na+/J= ATPases in distal nepheron. Increases serum Na+ and blood volume
ADH or Vasopressin
Post petuitary. Plasma volume too low or osmolarity too high. Causes water reabsorption by causing distal epithelial cells to become mater permeable. Flow into medula. Concentrates urine and dillutes blood. Works with Aldosterone.
Released by C cells of thyroid gland. When serum Ca2+ levels are too high it is secreted. Causes lowering of Ca2+ through deposition into bone, reduced gut Ca2+ absorption, and excretion into urine
parathyroid of the thyroid gland. Function in opposite direction of calcitonin
Produced by the Kidney. Increased synthesis of blood vessles in the bone marrow