Bio: Renal and Digestive System Flashcards
What do the following organs do:
Colon, liver, kidney
What hormone secreted by kidney?
Colon -> eliminates solid waste, material that is eaten but not absorbed into blood
liver -> eliminates hydrophobic waste, material that is eaten and absorbed into the blood, too hydrophobic to dissolve in plasma, synthesized urea so important in excretion, releases wastes it chemically modifies into bile
kidney -> eliminates hydrophilic waste, material that is eaten and absorbed into the blood, dissolved in plasma
-> Blood pressure regulation, pH regulation, osmotic regulation, produce EPO (erythopotein) increase RBC formation, activate vitamin D, gluconeogenesis (limited)
What is internal and external urinary sphincter tissue made of? Is each somatic or autonomic?
Internal urinary sphincter -> smooth muscle tissue, involuntary (autonomic)
External urinary sphincter -> skeletal muscle, somatic (voluntary)
Also ureter (from kidney to bladder) and bladder are muscular
Nephron
produces urine and filters blood
3 processes to produce urine (and a 4th extra one) what goes in or out in each (what cannot pass through and why)?
What is our glomerular filtration rate? How effective is it? What step is it connected to?
Filtration -> Passage of pressurized blood over a filter (like a coffee filter). Cells and proteins remain in the blood (like coffee grinds), while water and small molecules are squeezed out into the renal tube, fluid in this tubule is called filtrate
moving a substance (blood plasma) across a membrane (capillary wall) using pressure (blood pressure)
Reabsorption -> move substance from the filtrate to the blood, selective reabsorption (by secondary active transport) - glucose - amino acids - water - Na+ PROTEINS TOO LARGE TO PASS THROUGH
Glomerular filtration rate (GFR) = 125 mL/min, 99% of the original volume of filtrate is reabsorbed
Glomerular filtration is occurs due to the pressure gradient in the glomerulus. Increased blood volume and increased blood pressure will increase GFR.
Secretion: move a substance from the blood to the filtrate usually via active transport (increases rate at which substances are eliminated from the blood), like reabsorption, secretion occurs all along the tubule, but most secretion takes place in the DCT and the collecting duct
- drugs
- toxins
- creatinine
Dilution and Concentration: collecting duct -> this is step where there is selective reabsorption of water, and where we decide to make concentrated urine or dilute urine
Imagine/describe what happens in each of the following regions of nephron, where do hormones act?
Where does most reabsorption and secretion takes place?
Afferent arteriole
Efferent arteriole
Glomerulus and Bowman’s capsule (what does constriction of efferent arteriole result in?)
Proximal convoluted tubule (PCT)
Loop of Henle (what is it permeable/impermeable to?
Distal convoluted tubule
Collecting duct (what affects its function?)
What happens if you ran a marathon and sweat?
What happens if you have a longer loop of henle?
Afferent arteriole -> blood comes in
Afferent arteriole -> blood comes out
Glomerulus -> blood from afferent arteriole branches into a ball of capillaries called the glomerulus where filtration
-> constriction of efferent arteriole result in high pressure in the glomerulus, which causes fluid (blood plasma) to leak out of the glomerular capillaries and the fluid passes through a filter into Bowman’s capsule
Proximal convoluted
tubule (PCT) -> most reabsorption and secretion takes place here, all solute movement into blood (glucose -> actively transported out of filtrate by cotransporter, aa, Na+) is accompanied by water movement into blood, relatively unregulated, toxins also move into proximal convoluted tubule
Loop of Henle -> descending portion = permeable to water (water leave loop), impermeable to salt
Sets up concentration gradient in medulla
Water recollection mxn
Ascending portion = impermeable to water and permeable to salt (Na+ leaves tubule by passive diffusion at the beginning of ascent and pushed out by active transport by end of ascent)
Distal convoluted tubule (DCT) -> specialized reabsorbtion/secretion control, regulated by hormones -> reabsorption of water and urea in response to ADH
Collecting duct -> regulated water reabsorption by ADH/vasopressin (anti-diuretic hormone), when present makes cells permeable to water and increases blood pressure
ADH can be inhibited by caffeine and alcohol (less ADH, less water in blood, more water in urine)
ADH responds to blood osmolarity = blood concentration
If ran marathon and sweat, have more ADH to reclaim water
If you have a longer loop of henle, more likely to stay hydrate bc it is a water recollection mxn, more opportunity for water to come out of loop
Describe process (How/what detected this, what hormones secreted, from where, to where and the effect) if blood pressure falls
What hormones affect distal nephron (DCT and collecting duct)
If blood pressure falls, the Juxtaglomerular cells in the afferent ateriole (JG cells are baroreceptors that sense this decrease in blood pressure) kidney secretes renin which catalyzes the conversion of angiotensinogen (made in the liver) into angiotensin I
which is further converted to angiotensin II by angiotensin converting enzyme (ACE) in the lungs
Angiotensin II is a powerful vasoconstrictor that immediately raises the blood pressure and stimulates the release of aldosterone, which helps raise blood pressure by increasing sodium (and, indirectly water) retention. This then increases blood volume which also increases blood pressure
Also does…
-> increase blood osmolarity
-> increase ADH release
-> increase K+ secretion which happens in collecting ducts
ADH and aldosterone affect distal nephron (DCT and collecting duct)
What does vasoconstriction do to blood pressure?
increase blood pressure, bind receptors on adrenal cortext to increase aldosterone release which increases Na+ reabsorption and then increases water reabsorption
Kidney cares about increasing blood pressure, but if have high blood pressure kidney does not deal with that
What happens when there is decreased urine osmolarity in distal tubule?
The cells of the macula densa are chemoreceptors, and monitor filtrate osmolarity in the distal tubule. When filtrate osmolarity decreases (indicating a reduced filtration rate) , the cells of the macula densa stimulate JG cells to release renin
The macula densa also causes a direct dilation of the afferent arteriole, increasing blood flow to (and thus blood pressure and filtration rate in) the glomerulus.
Distal tubule -> chemoreceptor checks concentration of particles, looks at filtrate osmolarity and if sees low concentration in filtrate (if filtrate osmolarity falls) this means we must not be filtering enough fluid
What is special about the loop of henle/ what does it do -> the loop of henle is a ______?
The loop of Henle is a countercurrent multiplier that makes the medulla very salty, and this facilitates water reabsorption from the collecting duct. This how the kidney is capable of making urine with a much higher osmolarity than plasma
descending loop permeable to water but not ions, ascending loop permeable to ions but not water and the parts of loop go in opposite directions
What happens if have high blood pressure?
High blood pressure -> Atria of heart stretch -> Right atrium releases atrial natriuretic peptide (ANP) -> vasodilator which:
1) lowers blood pressure
2) inhibits renin
3) inhibits aldosterone release (inhibit Na+ reabsorption)
***Important : renal regulaiton of pH is fast/slow so if have chronic/long term issue what is the best means of compensation?
When plasma pH is too high, HCO3- is excreted in the urine; when the plasma pH is too low, H+ is excreted
Enzyme carbonic anhydrase catalyzes conversion of CO2 into carbonic acid (H2CO3), which dissociates into bicarbonate plus a proton. Once this reaction has taken place, the kidney can reabsorb or secrete bicarbonate or protons as needed.
Generally speaking, protons are secreted and bicarbonate is reabsorbed and the amounts are adjusted to adjust pH
Renal adjustments are SLOW, but pH regulation is fast
Important : renal regulaiton of pH is slow If you have chronic issue/long term the resp system won’t help you that much (you won’t be changing your breathing every 10 sec), the renal system MUCH better for dealing with chronic issue -> Kidney has receptors to recognize pH and change amount of H+ secreted and bicarbonate see diagram (helpful)
Online: About 85 to 90% of the filtered bicarbonate is reabsorbed in the proximal tubule and the rest is reabsorbed by the intercalated cells of the distal tubule and collecting ducts.
Alimentary canal
Accessory organs
The hepatic portal vein carries deoxygenated blood from the alimentary canal into the liver, where it is filtered before continuing to the heart via hepatic vein and inferior vena cava
____, _____, ______ are part of the alimentary canal and their blood supplies drain into the hepatic portal vein to be filtered by the liver
Blood that passes through the kidneys drains directly into the inferior vena cava via the renal veins
Alimentary canal -> muscular tube that goes from mouth to anus
Accessory organs -> have digestive function, not part of tube (liver, gal bladder, pancreas)
Stomach, small intestine, and colon
Liver -> what does it do?
What is special about bile?
makes bile to emulsify fats for easier digestion
Bile is amphipathic -> polar head and nonpolar tail
Liver has Bile -> emulsify fats for easier digestion, all nonpolar portion of bile go to fat
Next image, don’t worry too much about it, ex. you just ate McDonalds -> surface of bile polar and epithelial cells also polar so it can throw fats in epithelial cell layer and then fat can get hugged by proteins called Chylomicrons and make the lacteals take them up and dump into circulatory system and then go to adipose cells or cells that need that E
enteric
Nervous system keep a baseline state of contraction
If don’t have too much parasympathetic or sympathetic then that means you just have regular enteric
Gal bladder
Gallbladder Store and concentrate bile so if you lose gallbladder shouldn’t eat fatty foods, other microorganisms will break down fats for you and can overpopulate and produce gas and give you hard time (side note don’t need to know but when everyone eating alestra which you can’t break down but your other friend microorganisms eat it)
