Digestive System Flashcards
What acronym can you use to remember the sequence of duodenum → jejunum →** ileum** in the small intenstine?
Dow Jones Industrial
What are the objectives of the small intestine?
- neutralizing the highly acidic chyme from the stomach
- continuing chemical digestion
- vitamin & nutrient absorption
This enzyme produced in the stomach is reponsible for the breakdown of fats
gastic lipase
When you think of stomach enzymes, think of pepsin and gastric lipase
What prevents pepsin from immediately doing proteolytic activity when it isn’t necessary
Chief cells secrete its inactive form pepsinogen, which is cleaved under highly acidic conditions to become its active form, pepsin
Enzymes secreted by the SI from its microvilli to digest fats and/or proteins
brush border enzymes
recall that disaccarides are a common form in which carbs are consumed
List the functions of the pancreas wrt the digestive system
- helps duodenum digestion by secreting alkaline fluid containing digestive enzymes that can break down all major biomolecule classes
- lipases (fat)
- proteases (protein)
- amylases (sugars)
What does bile consist of?
Bilurubin, bile salts, and some fats
bile emulsifies lipids and converts them to micelles
How is highly acidic chyme from the stomach neutralized via other digestive system organs?
- pancreas secretes alkaline fluid rich with bicarbonate
- liver’s bile is slightly alkaline
- duodenum secretes bicarbonate buffer via Brunner’s glands
Qhat region(s) of the small intestine are involved in nutrient absorption?
jejunum & ileum
Cells of the intestinal lining, characterized by microvilli
enterocytes
Name the regions of the large intestine in order (excluding the appendix)
- cecum
- ascending colon
- transverse colon
- descending colon
- sigmoid colon
- rectum
What is the pouch connected with the ileum through the ileocecal valve?
the cecum
Where is the largest community of bacteria in the human body located?
The gut microbiota is located in the large intestine
What is the role of bile?
To emulsify lipids so that digestive enzymes can do their work
Name the two hormones that regulate hunger
ghrelin & leptin
think “grrr” (I’m hungry!) for ghrehlin , and leptin is the opposite, it lets you know that you are full
What hormone is released by the stomach and pancreas when the stomach is empty?
ghrehlin
ghrehlin promotes appetite
Which hormone is secreted by adiptocytes and promotes feelings of satiety?
leptin
What is this hormone?
G-cells in the stomach secrete a hormone that promotes digestion by stimulating parietal cells to secrete gastric acid (HCl)
gastrin
Acidic chyme in the duodenum triggers the release of which hormone from S cells? What does this hormone do?
**secretin **triggers the secretion and release of bicarbonate rich mucus from the pancreas
think: pH regulator!
this is to neutralize the acidic chyme and promote the optimal functioning of the digestive enzymes that do their work in the small intestine
This hormone is secreted by the small intestine and stimulates the release and secretion of digestive enzymes from the pancreas, and the release of bile from the gallbladder
cholecystokinin (CCK)
think: digestion helper!
Which hormone produced from the GI system & hypothalamus helps slow down digestion by inhibiting the release of other hormones, and slowing the rate at which the stomach empties?
somatostatin
think: pumping the brakes on digestion
somatostatin also inhibits the release of growth hormone when released from the hypothalamus. This makes sense because GH is released from the hypothalamus
it’s released from the GI tract, pancreas, CNS, and hypothalamus!
Part of the autonomic nervous system that regulates the digestive functions of the gastrointestinal tract
enteric nervous sytem
think: part of ANS involved in digestion
Describe the general steps for carbohydrate absorption
include what they get broken down into, the cell transport used to get them across the membrane
- Carbs → monosaccharides
2.a 2º active transport coupled to Na+ gets glucose & galactose into epithelial cells
2.b Facilitated diffusion used for fructose - Monosaccharides enter circulatory system via facilitated diffusion
- Facilitated diffusion pushes monosaccharides in bloodstream
Describe how lipids are absorbed
include what they get broken down into, the cell transport used to get them across the membrane
- Lipids → micelles w/ aid of bile salts
- Lipid molecules break away for epithelial cell absorption
- Fats & cholesterol can diffuse through plasma membrane
- Fats & fat soluable vitamins are combined into chylomicrons
- Chylomicrons are released into interstitial space
- Fat is transported from interstitial space → lacteals
- Lipids pass through lymphatic system
- Lipids eventually drain into venous system
chylomicrons = fat droplets
Small intestine epithelial cells combine fatty acids + monoglycerides = triglycerides to avoid the concentrations of fats to equalize, which would cause absorption to stop
Fill in the blank
the hepatic portal vein runs from the capillaries of the ____ to the liver
** small intestine **
small intestine capillaries → hepatic portal vein → liver → hepatic portal system
What is the benefit of the hepatic portal system? That is, blood from small intestine being processed by the liver before entering the circulatory system?
The liver can:
* detoxify compounds
* metabolize medications/drugs
* store excess carbs as glycogen
* store exess fatty acids as triglycerides
* mobilize lipids into circulation as lipoproteins
* breaking down glycogen to release glucose (if necessary)
fill in the blanks
Proteins are broken down in the stomach by ____, and in the small intestine by ____ (name three)
pepsin in stomach;
trypsin and chymotrypsin, and carboxypeptidase in small intestine
____ is an enzyme that cleaves proteins on the carboxyl end of lysine or arginine (execept when followed by proline)
Trypsin
released in small intestine
____ are a class of enzymes that break down proteins from the amino end
aminopeptidases
it tells you what it does in the name…. amino peptidase , telling you it breaks down proteins at the amino end
Describe the path of proteins as they go from your mouth to a state where they can be used in the body
- Pepsin breaks down proteins in stomach
- Small intestine uses trypsin and aminopeptidases for more breakdown
- Single amino acid residues enter epithelial cells lining lumen of small intestine
- Amino acids enter circulatory system
Describe the path of carbohydrates as they go from your mouth to a state where they can be used in the body
- Salivary amylase breaks downs starches → dissachharides
- Small intestine breaks starches into monosaccharides via pancreatic amylase (one of many enzymes)
- Monosaccharides enter epithelial cells of SI
- Monosaccharides enter circulatory system
- Cellulose and undigested starch → large intestine
- “…” broken down or digested by gut flora → short-chain fatty acids
Describe the path of triglycerides as they go from your mouth to a state where they can be used in the body
- Digested in mouth by lingual lipase
- Pancreatic lipase breaks down most of lipids in stomach
- Resulting free fatty acids & monoglycerides are seperated by bile salts into micells
- Lipids enter cells lining small intestine
- Lipids packaged into chylomicrons
- Chylomicrons are released into lacteals
- Lacteals drain into lymphatic system
True or False
It is possible to overdose on vitamin C
False. It is nearly impossible to overdose on water-soluble vitamins
Vitamins C & B in excess are excreted from the urine
However, it is quite possible to OD on fat-soluble vitamins i.e A, D, E, & K
True or False
Our bodies produce substantial amounts of vitamins
False. The vast majority of our vitamin levels are influenced by our diet
and sun exposure for vitamin D
Vitamins and their derivates also serve as what type of biochemical actors in physiological reactions?
Coenzymes/cofactors
i.e vitamin B2 (Riboflavin) is a coenzyme involved in the ETC
Name the vitamin
Helps with vision (low-light and color)
Vitamin A
also good for healthy skin regeneration
Name the vitamin
Helps calcium and phosphate absorption from the gut
Vitamin D
Name the vitamin
Is an antioxidant; scavenges free-radicals
Vitamin E
think: vitamin E and berrIES (berries have shit ton of antioxidants!)
Name the vitamin
Helps to make various proteins that are needed for *blood clotting *and the building of bones
Vitamin K
think!* K*lotting
Name the vitamin
Cofactor for reactions in collagen synthesis, and is also an antioxidant
Vitamin C
think about skincare lol. Also, vitamin C and vitamin E work well on the skin together because they’re both antioxidants!
Name the vitamin
Coenzyme in important metabolic reactions
thiamine
B1
Name the vitamin
Coenzyme involved in ETC, precursor of FAD
riboflavin
Vitamin B2
Name the vitamin
Precursor of NAD and NADP
niacin, niacinamide
Vitamin B3
Name the vitamin
Required for synthesis of CoA, as well in metabolism
Vitamin B5
Name the vitamin
Used as a coenzyme in many metabolic reactions
pyridoxine
Vitamin B6
B6 and B1 serve the same function: coenzymes in metabolic reactions
Name the vitamin
Cofactor for several carboxylase enzymes in metabolic reactions
biotin
Vitamin B7
Name the vitamin
Ensures proper neurological development in pregnancy, required for fertility and RBC synthesis
folic acid
Vitamin B9
Name the vitamin
Coenzyme in metabolic reactions, especially DNA synthesis and lipid/amino acid metabolism
cyanocobalamin + derivaties
B12
Blood is filtered to form ____ in the kidneys
urine
if your kidney is not doing alright, this is why you will find blood in urine (hematuria)
The kidneys are supplied blood via the ____, and then drain into the ____
renal arteries supply kidneys with blood, renal veins are what the kidneys drain into
The outside of the kidney is surounded by protective tissue called….
renal capsule
The outer region of the kidney is called the ____ , and the inner region is called the ____
outer region: renal cortex
inner region: renal medulla
What functional region of the kidneys produce urine?
Nephrons
The ____ is the part of the nephron that does initial urine filtration, while the ____ projects downwards into the medulla before returning up back to the cortex, at which point the urine drains into the ____
renal corpuscle, renal tubule, collecting duct
The collecting ducts eventually drain urine into the ____, which becomes the ureter
renal pelvis
collecting duct → medullary pyramids → minor calyces → major calyces → renal pelvis → ureter
The ureters drain urine downwards from the kidney into the ____, which rests on the pelvic floor
urinary bladder
Urine is released from the bladder into the ____, where it exists the body
Urethra
The release of urine through the urethra is caused by the ____
urethral sphincter
The renal corpuscle contains the ____ which is a bunched up set of capillaries through which water, ions, and small molecules filter out and are gathered into ____ , which wraps around it
Glomerulus: Bundled set of capillaries that are filtered into Bowman’s capsule
Blood is supplied to the glomerulus through an ____ and exits through an ____
afferent arteriole; efferent arteriole
fluid collected in Bowman’s capsule is called glomerular filtrate
What are the three main parts of the renal tubule?
proximal convoluted tube, loop of Henle, and distal convoluted tube
Which major region of the nephron is reponsible for regulating water volume and urine concentration?
renal tubule
Region of the kidney whose main functions are 1. filtering various substances in the blood and 2.) regulating fluid/salt content of urine
Nephron
Name the nephron region
Large amounts of salts, water souluble vitamins, free amino acids, glucose, and water are reabsorbed here. Secretion of waste products into the urine also occurs here
proximal convoluted tube (PCT)
Wastes excreted by the PCT include creatine, ammonia, and medications
Name the nephron region
The main function is to reabsorp water and salt (reducing the amount of these ending up in filtrate) , and creating an osmotic gradient in the renal medulla
loop of Henle
The deeper you go into the renal medulla, the [greater/lesser] the concentration of solutes
greater ; this facilitates the osmotic process throughout the loop of Henle
Water is reabsorbed in the ____ of the loop of Henle, and salt is transported out of the ____
Water reabsorption: descending limb
Salt leaves: ascending limb
The process of using energy to generate an osmotic gradient that enables you to reabsorb water from the tubular fluid and produce concentrated urine
Name the region of the nephron
Is partly responsible for the regulation of potassium, sodium, (think: water regulation), calcium, and pH. Increases calcium reabosrption in presence of PTH. Can contribute to pH regulation by secreting or absorbing hydrogen ions as needed
distal convoluted tube (DCT)
Name the nephron region
The main role is the reabsorption of water, through the action of anti-diuretic hormone (ADH) and aquaporins.
collecting duct
Name the hormone
Promotes the secretion of sodium in the urine, which draws water with it, increasing the amount of H2O expelled in the urine and decreasing BP
atrial natriuretic peptide (ANP)
opposite of ADH
What are the three main hormones that effect fluid balance?
Aldosterone, ADH, and ANP
p.251 of BP
The kidney secretes renin when….
When your blood pressure drops too low or when there’s not enough sodium in your body, or when there is a lot of sympathetic NS signaling
Renin causes a hormone that is released from the liver to be cleaved to form another hormone. Which hormone is this?
Angiotensin I is converted to angiotensin II by an enzyme called ____
angiotensin converting enzyme (ACE) is released from which organ?
Name the hormone
____ increases BP via vasoconstriction and also triggers the release of aldosterone by stimulating the adrenal cortex
Name the hormone
Acts on the kidneys to ↑Na+ reabsorption which ↑ water reabsorption (in the presence of ADH), which ↑ plasma volume of blood which ↑ BP
aldosterone
Describe vasopressin’s role in regulating blood pressure wrt water and plasma volume of blood
↑ H2O retention = ↑ plasma volume of blood ↑ BP
vasopressin = ADH
