Term
| What are the 4 functions of epithelial tissue |
|
Definition
1.provide physical protection
2.control permeability and allow absorption/secretion
3.provide sensation
4.produce specialised secretions |
|
|
Term
| How does epithelial tissue produce specialised secretions |
|
Definition
1.release their secretions onto the surface of the epithelium (to provide physical protection/temperature regulation)
2.release them into surrounding interstitial fluid and blood (to act as chemical messengers |
|
|
Term
| How is epithelia classified |
|
Definition
|
|
Term
| Describe squamous epithelia |
|
Definition
|
|
Term
| Describe simple squamous epithelia |
|
Definition
Single layer
Used in absorption and secretion |
|
|
Term
| Describe stratified squamous epithelia |
|
Definition
Many layers
Protects against attacks
Keratin protein adds strength and water resistance |
|
|
Term
| Describe cuboidal epithelia |
|
Definition
|
|
Term
| Describe simple cuboidal epithelia |
|
Definition
single layer
secretion and absorption |
|
|
Term
| Describe stratified cuboidal epithelia |
|
Definition
Many layers
Sweat ducts and ammory ducts |
|
|
Term
| Describe columnar epithelia |
|
Definition
|
|
Term
| Describe simple columnar epithelia |
|
Definition
Single layer
Protection, secretion and absorption |
|
|
Term
| Describe stratified columnar epithelia |
|
Definition
|
|
Term
| Epithelial cells are polarised, what does this mean? |
|
Definition
| they can target proteins to discrete cell domains |
|
|
Term
| What is the role of a tight junction |
|
Definition
to seal the gap between epithelial cells
prevents diffusion of plasma membrane proteins (eg receptors/channels) between apical and basolateral domains |
|
|
Term
| What is the role of an adherens junction |
|
Definition
| connect actin filament bundle in one cell with that in the next cell |
|
|
Term
| What is the role of a desmosome |
|
Definition
| connects intermediate filaments in on cell to those in the next cell |
|
|
Term
| What is the role of gap junctions |
|
Definition
| allows the passage of small water soluble molecules from cell to cell |
|
|
Term
| How can apical surfaces be specialised |
|
Definition
Microvilli: increase membrane surface area by 20/30 fold. Especially involved in bulk absorption or secretion.
(motile) Cilia: maintain flow of fluid over the surface of epithelia
(non-motile) cilia: involved in sensing flow |
|
|
Term
| Define absorption and give an example |
|
Definition
movement from the external compartment (lumen of the renal tube/gut_ to the internal compartment (blood)
eg glucose absorption in the gut and renal tube |
|
|
Term
| Define secretion and give an example |
|
Definition
movement from the internal compartment to the external comparment
eg. H+ and K+ in the renal tubule; HCO3- secreted by pancreas |
|
|
Term
|
Definition
|
|
Term
| How can net flux be determined |
|
Definition
| by using radioactive isotopes as tracers which we assume move in exactly the same way and by the same routes as the non radioactive solutes |
|
|
Term
| Describe passive transport across cell membranes |
|
Definition
-solutes move down their electrochemical gradients
-can occur via pores/channels
-transporters facilitate diffusion of small non electrolytes (eg glucose) |
|
|
Term
| Describe primary active transport across cell membranes |
|
Definition
-energy to drive comes directly from ATP
-substrate moves against an electrochemical gradient |
|
|
Term
| Describe secondary active transport across cell membranes |
|
Definition
-energy to drive comes from electrochemical gradient for one substrate (set up from primary active transport)
-second substrate moves against its electrochemical gradient |
|
|
Term
| Describe the mechanics of NaCl transport |
|
Definition
-apical entry of Na+
-pumped out the basal membrane into into the interstitium
-3Na+ are pumped out whilst 2K+ are pumped in (requires ATP)
-K+ is recycled via pumpa and leak
-Paracellular movement of Cl- |
|
|
Term
| Describe sugar absorption |
|
Definition
-Na+ glucose symporter (driven by high extracellular Na+) enters the cell. SECONDARY ACTIVE.
-Glucose leaves the cell into the ECF via PASSIVE transport
-Na+ leaves the cell by a Na+K+ pump. PRIMARY ACTIVE. |
|
|
Term
| How would water move through those cells? |
|
Definition
| Moves lumen to ECF through paracellular junctions/transcellular pathway |
|
|
Term
| Where in the body could this represent? |
|
Definition
| Renal proximal tubule or small intestine |
|
|
Term
| Why does net solute movement usually drive net fluid movement? |
|
Definition
| water flows from areas of low osmotic pressure to areas of high osmotic pressure |
|
|
Term
|
Definition
one tube, 8-9m long, up to 15cm wide
mouth > pharynx > esophagus > stomach >small intestine >colon > rectum > anus |
|
|
Term
|
Definition
20-55mm long, about 50 micrometres wide
Glomerulus > proximal tubule > loop of Henle > Distal tubule > collecting duct
More than a million of them |
|
|
Term
| What do the kidneys maintain |
|
Definition
| the volume and composition of the body's fluids |
|
|
Term
| What hormones regulate the kidneys |
|
Definition
|
|
Term
|
Definition
| an adrenal steroid that promotes sodium reabsorption |
|
|
Term
|
Definition
| a hormone released form the heart that promotes loss of sodium (natriuresis) |
|
|
Term
|
Definition
| a hormone released from the pituitary glands that promotes retention of water. Produces small more concentrated volume of water |
|
|
Term
|
Definition
| a parathyroid hormone that affects excretion of phosphate and calcium as well as synthesis of vitamin D |
|
|
Term
| Which hormones do the kidneys synthesise and release? |
|
Definition
|
|
Term
|
Definition
| involved in the formation of angiotensin II, a peptide with effects on the vasculature and adrenal gland. |
|
|
Term
|
Definition
| involved in calcium and phosphate metabolism |
|
|
Term
|
Definition
| a protein that promotes formation of RBCs |
|
|
Term
| What is the rate of renal plasma flow |
|
Definition
|
|
Term
| What is the glomerular filtration rate |
|
Definition
|
|
Term
| How much salt is filtered each day? |
|
Definition
|
|
Term
| Where do the kidneys lie? |
|
Definition
| between the levels of the 12th thoracic and 3rd lumbar vertebrae |
|
|
Term
| Which kidney is lower than the other and why? |
|
Definition
| The right kidney is lower because it is overlain by the right lobe of the liver (and spleen) |
|
|
Term
| What is the source of ADH? |
|
Definition
|
|
Term
| Which is more lateral the renal cortex or renal medulla? |
|
Definition
|
|
Term
| How much blood plasma do the kidneys filter? |
|
Definition
|
|
Term
| Describe the arterial blood supply to the nephron |
|
Definition
| Renal artery > segmental arteries > interlobal arteries > arcuate arteries > cortical radiate arteries > NOW IN THE NEPHRONS: afferent arterioles > Glomerulus > Efferent arteriole |
|
|
Term
| Describe the venous blood supply to the nephron |
|
Definition
| Efferent arterioles > Peritubular capillaries > OUT OF NEPHRON: venules > cortical radiate veins > arcuate veins > interlobal veins > renal vein |
|
|
Term
| What are the functions of peritubular capillaries and what do they surround |
|
Definition
-provides nutrients
-retrieve reabsorbate
-remove metabolites
renal tubule |
|
|
Term
| State the tubular components in order |
|
Definition
| Glomerulus > Bowman's/renal capsule > Loop of Henle > distal convoluted tubule > collecting duct |
|
|
Term
| What is glomerular filtration |
|
Definition
| movement of plasma solutes and water across glomerular capillaries into Bowmans space and delivering a 'protein free' ultrafiltrate of plasma into the proximal tubule |
|
|
Term
| How is the movement of fluid caused in urine formation? |
|
Definition
| the force of filtration causes movement along the renal tubule |
|
|
Term
| What is tubular reabsorption? |
|
Definition
| movements of solutes and water from the lumen of the tubule back into the blood |
|
|
Term
| What is tubular secretion? |
|
Definition
| movements of solutes (not water) from the blood into tubular lumen |
|
|
Term
| What effects to diuretics have |
|
Definition
|
|
Term
|
Definition
| water channels are abundant in plasma membrane of the proximal tubular cells (apical and basolateral). This allows water to move osmotically after solutes have been reabsorbed. |
|
|
Term
| Proximal tubule: Which compounds are actively absorbed and hence conc falls? |
|
Definition
| glucose, amino acids, bicarbonate |
|
|
Term
| Why does insulins conc increase |
|
Definition
| It is not absorbed or secreted by the tubule so its conc rises as water follows other absorbed solutes out of tubule |
|
|
Term
| Why does sodium concentration remain constant |
|
Definition
| It is the main cation in the tubular fluid. As it is reabsorbed water is being reabsorbed at the same rate, so conc remains constant. |
|
|
Term
| How is concentrated urine achieved in the loop of henle with no active water pumps? |
|
Definition
-an osmotic gradient to extract the water from the tubular fluid
-the loop of henle achieves this by pumping salt into the interstitium of the renal medulla |
|
|
Term
| Whats present in the descending limb and what does this mean? |
|
Definition
lots of APQ1 present
therefore high water permeability |
|
|
Term
| Whats present in the ascending limb and what does this mean? |
|
Definition
lots of mitochondria
active salt pumping into interstitium making it hypertonic |
|
|
Term
| How is blood moved in and out of the medulla without destroying the osmotic gradient set up by the loop? |
|
Definition
capillaries have own hairpin arrangement
blood flows down, loses water to interstitium and picks up salt
blood flows up, loses salt and picks up water |
|
|
Term
|
Definition
| major antidiuretic hormone in mammals |
|
|
Term
| What does a antidiuretic do? |
|
Definition
|
|
Term
|
Definition
|
|
Term
| What does the ability to produce conc urine depend on? |
|
Definition
| medullary osmotic gradient generated by loop |
|
|
Term
| What does change in permeability depend on? |
|
Definition
-insertion of APQ2 water channels into apical plasma membrane
-APQ2 are only seen in principle cells |
|
|
Term
| What events follow when vasopressin/ADH bind to receptors in basolateral membrane? |
|
Definition
This is a GPCR linked to adenylate cyclase, cAMP, protein kinase A which phosphorylates APQ2.
APQ2 moves to apical membrane and are inserted |
|
|
Term
|
Definition
| APQ3/4 water channels on basolateral membrane |
|
|
Term
| What occurs when ADH levels fall? |
|
Definition
| AQP2 is retrieved endocytically and membrane returns to highly permeable state. |
|
|
Term
| What is the main stimulus to ADH release |
|
Definition
|
|
Term
| What can also trigger an ADH release |
|
Definition
| fall in blood pressure/circulatory volume |
|
|
Term
| What is the normal osmolarity |
|
Definition
|
|
Term
| What follows increased osmolarity |
|
Definition
Water retention or thirst
then normal osmolarity and increased ECF volume |
|
|
Term
| What follows decreased osmolarity |
|
Definition
Water excretion
then normal osmolarity and decreased ECF volume |
|
|
Term
|
Definition
| specialised cells which sense the amount of water, in the glomerulus. |
|
|
Term
| what occurs if water levels are too high |
|
Definition
| signal afferent artery to contract, decreasing GFR |
|
|
Term
| what occurs if water levels are too low |
|
Definition
| stimulate the granular cells to secrete renin |
|
|
Term
| Functions of the GI tract |
|
Definition
ingestion
mechanical processing
secretion (release of water, acids, enzymes, buffers and salts)
absorption (movement of organic substrates, electrolytes, vits and water) |
|
|
Term
| What is the Gi tracts blood supply |
|
Definition
Coeliac artery (becomes hepatic)
Superior mesenteric artery
Inferior mesenteric artery |
|
|
Term
| Describe the general structure of the gi tract (inner to outer) |
|
Definition
mucosa
submucosa
muscularis externa
serosa |
|
|
Term
| What are the stomach glands? |
|
Definition
parietal cells
chief cells
g cells |
|
|
Term
| what do the parietal cells do |
|
Definition
|
|
Term
|
Definition
| secrete pepsinogen (inactivates proenzyme) which is converted by hcl in gastric lumen to pepsin |
|
|
Term
|
Definition
| secrete gastrin (endocrine stimulator of parietal cells) |
|
|
Term
| What are the functions of bile? |
|
Definition
emulsification of fat
-dietry lipids are not water soluble
-mechanical processing in stomach creates large droplets containing lipids
-bile breaks droplets apart therefore increases surface area exposed to pancreatic lipase |
|
|
Term
| What are the main GI hormones |
|
Definition
|
|
Term
|
Definition
| comes from g cells and modifies acid secretion and stimulates gastrin contractions |
|
|
Term
| What are the 3 phases of gastric secretion |
|
Definition
| cephalic, gastric and intestinal |
|
|
Term
| What occurs in the cephalic phase of secretion? |
|
Definition
1.the taste/smell/tactile sensation of food in the mouth sends nerve impulses to the medulla oblongata
2.this increases parasympathetic activity
3.vagus nerve innervate the submucosal plexus of the stomach |
|
|
Term
| What do the postganglionic parasympathetic fibres innervate? |
|
Definition
parietal and cheif cells
G cells |
|
|
Term
| What is the outcome of the cephalic phase? |
|
Definition
G cells increase gastrin secretion and plasma gastrin
acid and pepsinogen secretion is increased |
|
|
Term
| What occurs in the gastric phase of secretion? |
|
Definition
1.begins with arrival of food in stomach
2.stimuli include:
-distension of the stomach
-increase in the pH of gastric contents
-presence of undigested food in stomach |
|
|
Term
| What are the short and long reflexes? |
|
Definition
short: straight to G cells
long: chemoreceptos and mechanoreceptors |
|
|
Term
| What is the gastric of the cephalic phase? |
|
Definition
| Acid and pepsinogen secretion |
|
|
Term
| What is the stimuli for secretin? |
|
Definition
|
|
Term
| What is secretin secreted by? |
|
Definition
| APUD cells in duodenal mucosa |
|
|
Term
|
Definition
|
|
Term
|
Definition
-stimulates fluid and bicarbonate secretion
-weak effects on pancreatic proenzymes and insulin
-inhibits gastric and intestinal motility
-inhibits gastric acid secretion
-example of negative feedback |
|
|
Term
| What is the stimuli for CCK-PZ secretion? |
|
Definition
| fatty acids, proteins and amino acids |
|
|
Term
| What is CCK-PZ secreted by? |
|
Definition
| APUD cells in duodenal mucosa |
|
|
Term
|
Definition
| gall bladder and pancreas |
|
|
Term
| What are the effects of CCK-PZ |
|
Definition
-gall bladder contraction
-relaxation of Sphincter of Oddi
-stimulation of pancreatic secretion (bicarb and proenzymes)
-inhibits gastric emptying
-stimulates gastric and intestinal motility |
|
|
Term
|
Definition
anticipatory phase:
affects saliva production and medulla passes on signal to stomach to produce gastrin therefore producing acid and pepsin |
|
|
Term
|
Definition
gastric:
sensory receptors detect distension stimulates gastrin and to medulla |
|
|
Term
|
Definition
intestinal:
as food enters the duodenum, further hormone wave is triggered which causes the release of bile and pancreatic secretions into gut lumen |
|
|
Term
| Which nutrients must be digested before absorbed? |
|
Definition
carbohydrates
proteins
lipids |
|
|
Term
| Which nutrients can immediately be absorbed? |
|
Definition
water
electrolytes
vitamins |
|
|
Term
| What do brush border enzymes digest? |
|
Definition
tri and di saccharides
and tri and di peptides |
|
|
Term
| How are carbohydrates digested? |
|
Definition
-soluble amalyse (in saliva and pancreas) breaks internal alpha1-4 bonds (not alpha1-6 bonds)
-reamining short carbs broken by brush border enzymes
-monosaccharides absorbed by 2ndary active transporters |
|
|
Term
| why is fructose different? |
|
Definition
| fructose monosaccharides are absorbed passively |
|
|
Term
| What does gastric acid do to pepsinogen in the stomach |
|
Definition
| cleaves pepsinogen hence activating it into pepsin which degrades food proteins into peptides |
|
|
Term
|
Definition
| enzymes that help hydrolysis of polypeptides |
|
|
Term
| What is the major site of protein digestion |
|
Definition
duodenum
pepsin is inactivated here
trypsinogen is cleaved into trypsin which activates other enzymes |
|
|
Term
| What is the fate of the small produced peptides |
|
Definition
| diffuse into the brush border where peptidases chop them into amino acids and dipeptides |
|
|
Term
| Carbohydrates: how do starch/disaccharides become poly/disaccharides? |
|
Definition
salivary amylase (mouth)
pancreatic amylase (small intestine)
1,4 alpha bonds broken only |
|
|
Term
| Carbohydrates: how do poly/disaccharides become mono? |
|
Definition
| broken down by specific enzymes on brush border enzymes (small intestine) |
|
|
Term
| Carbohydrates: what is the fate of the produced monosaccharides? |
|
Definition
absorbed by secondary active transporters
transported to the liver via hepatic portal vein |
|
|
Term
| Proteins: how do proteins become large polypeptides |
|
Definition
pepsin (from stomach glands) in presence of HCl
stomach |
|
|
Term
| Proteins: how do large polypeptides become small poly and small peptides? |
|
Definition
| pancreatic enzymes trypsin (small intestine) |
|
|
Term
| Proteins: how small poly and small peptides become amino acids? |
|
Definition
| brush border enzymes small intestine |
|
|
Term
|
Definition
| diffuse into the brush border where peptidases chop them into amino acids and dipeptides |
|
|
Term
|
Definition
| mainly triglycerides and phospholipids |
|
|
Term
|
Definition
1.fats are broken down pacreatic lipase aided by bile salts which break up lipid droplets (increasing surface area)
2.mixed micelles diffuse close to the brush border, delivery contents to membrane |
|
|
Term
|
Definition
| monoglycerides and fatty acids complex with bile salts (which solubilise them) |
|
|
Term
| How are mono's re-synthesised back into tri's? |
|
Definition
once in the cell.
they must be broken down to cross the cell membrane. |
|
|
Term
|
Definition
| in the liver by hepatocytes |
|
|
Term
|
Definition
1.specific transports in the distal ileum move bile salts from the lumen of the DI to the intestinal capillaries
2.they are transported directly to the liver via the hepatic vein |
|
|
Term
| How are fat-soluble vitamins absorbed? examples |
|
Definition
absorbed with lipids
dissolved in lipid droplets, micelles, chylomicrons
A, D, E and K |
|
|
Term
| How are water-soluble vitamins absorbed? examples |
|
Definition
| required special transport proteins (Na+) |
|
|
Term
| How is vit b12 absorbed? examples |
|
Definition
absorbed only when bound to intrinsic factor
(secreted by gastric parietal cells) |
|
|
Term
| What would occur that meant you were no longer able to absorb vit b12? |
|
Definition
removed part of stomach (to lose weight)
lost aprt of small intestine (Chromes disease) |
|
|
Term
|
Definition
| precursor to rbc production |
|
|
Term
|
Definition
creatinine technique
measurement of creatinine conc and urine flow rate |
|
|
Term
| what occurs in the renal corpuscle |
|
Definition
|
|
Term
| proximal convulated tubule |
|
Definition
| reabsorption of water, ions and all organic nutrients |
|
|
Term
|
Definition
secretion of ions, acids, drugs and toxins
variable reabsorption of water, sodium ions and calcium ions |
|
|
Term
|
Definition
| variable reabsorption of water and reabsorption or secretion na, k, h and bicarb ions |
|
|
Term
|
Definition
|
|
