231 Physiology Term 2 - End of LO4, LO5 and 5 diseases Flashcards
Where does most absorption and digestion take place?
small intestine
What is the path of absorption for glucose and galactose?
Via cotransport with Na+
Where is aminopeptidase produced?
Small intestine from brush border
List the enzymes (in correct order) needed to break down glycogen.
Salivary amylase, Pancreatic amylase, dextrinase and glucoamylase, maltase
After proteins are broken down into amino acids what process is used to absorb them into the cells of the small intestine?
cotransport with sodium
Does the absorption of amino acids (and sodium) into the cells of the intestine wall require additional energy?
No, sodium spontaneously diffuse from high to low concentration transporting the amino acid for free
Is the movement of sodium and amino acids from the intracellular fluid, across the cell wall, into the blood, energetically a free process?
No. Although the amino acids do not require energy as they are moving from a high to low concentration the sodium potassium pump is required to move the sodium and this does require energy.
In terms of enzymes it is quite easy to break lipids down. Why is it difficult to digest them?
Because they are hydrophobic
What are the two roles of bile in lipid digestion?
Emulsification and micelle formation
Where do we get most of the protein digesting enzymes from in the small intestine?
From the pancreas.
True or false: The small intestine produces enzymes to breakdown lipids.
False. Enzymes in the small intestine that breakdown lipids come from the pancreas.
What groups of enzymes does the small intestine produce that attack nucleic acids?
Nucleosidases- Phosphatases
What activates trypsinogen and where is it produced?
Membrane-bound enteropeptidase activates trypsinogen and it is produced in the brush border of the small intestine.
Define bile salts.
Primarily salts of cholic and chenodeoxycholic acids, are cholesterol derivatives. They play a crucial role in both the digestion and absorption of fats
Define emulsification.
Bile salts in the duodenum break large fat globules into smaller fat droplets, increasing the surface area available to lipase enzymes. The non-charged side of bile salts will coat the smaller globules of fat so they can’t stick back together. Lipase then attacks.
List the functions of the kidney.
- Regulating the total volume of water in the body and the total concentration of solutes in that water (osmolality).
- Regulating the concentrations of the various ions in the extracellular fluids. (Even relatively small changes in some ion concentrations such as K+ can be fatal.)
- Ensuring long-term acid-base balance.
- Excreting metabolic wastes and foreign substances such as drugs or toxins.
- Producing erythropoietin and renin, important molecules for regulating red blood cell production and blood pressure, respectively.
- Converting vitamin D to its active form.
- Carrying out gluconeogenesis during prolonged fasting .
What are the main risk factors of emphysema?
- Smoking is the major risk factor
- You can also have hereditary factors; gene defective in producing alpha 1 antitrypsine proteins
- Sometimes it is heavily linked to occupations such as welding and mining
What are the three key processes of the kidney?
- filtration
- secretion
- reabsorption
Which substances in the blood should not be filtered?
proteins, red blood cells and white blood cells
Describe the process of filtration.
- It is basically a passive process where substances are moved across the pressure gradient, so they are going from high pressure to low pressure
- The high pressure is caused by the blood pressure and the surrounding glomerular capsule is a fairly low pressure
- Most substances are able to be filtered and this includes things that we would like to keep, including glucose, amino acids, sodium, water
- But substances that shouldn’t be filtered are large substances such as proteins and then your red and your white blood cells
- Once you have formed the filtrate and it has entered the glomerular capsule, then the urine is going to travel through the rest of the nephron
Define secretion.
Movement of substances from the surrounding capillaries, the blood, back into the urine.
Define tubular reabsorption.
Movement of substances from the urine into the surrounding capillaries.
Why might you suffer from respiratory alkalosis?
Hyperventillation due to stress and pain
How and where in the kidneys help solve respiratory alkalosis?
Reabsorb hydrogen ions in the collecting duct and secrete bicarbonate ions in the collecting duct
What are 3 main hormones that have effect in the kidneys?
- aldosterone
- ADH
- ANP
At what stage is the fluid considered urine?
Once it has been filtered in the glomerulus and passed into the proximal convoluted tubule.
When sodium ions are reabsorbed in the proximal convoluted tubule, what can they transport with them?
amino acids and glucose
Which hormones have an important effect in the collecting duct?
ADH, Aldosterone and ANP
When would we want to produce aldosterone?
To reabsorb sodium if you have low blood pressure -water will follow by osmosis. Or to secrete potassium
List several substances that are secreted into the kidney tubules.
H+, K+, NH4 +, creatinine, urea, and uric acid are all substances that are secreted into the kidney tubules.
Why might you suffer from respiratory alkalosis?
Hyperventilation due to stress and pain
How and where in the kidneys help solve the problem of respiratory alkalosis?
Reabsorb hydrogen ions in the collecting duct and secrete bicarbonate ions in the collecting duct primarily (according to Sally, very little secretion of bicarb happens in the PCT)
In addition to enzymes, what other pancreatic secretion is important?
Pancreas squirts a lot of bicarb ions; purpose if to reduce the acidity from the stomach
Why are protein digesting enzymes inactive most of the time?
So when there is no food, they don’t digest your tissues.
What will trypsin, chymotrypsin and carboxypeptidase do to proteins?
Trypsin and chymotrypsin are going to break down polypeptide into much shorter chains. Carboxypeptidase will then break down smaller polypeptides into amino acids.
From what end of the amino acid will carboxypeptidase chop?
the carboxylic acid end
What do you need to deal with hydrophobic fats?
bile salts from the liver
Where do bile salts get secreted into?
duodenum
What percentage of bile salts are reabsorbed by the ileum?
95%
What kind of energy do you need for co-transport?
kinetic energy
For carbohydrates, is there an exception in terms of path of absorption from happening via cotransport with sodium?
Yes, fructose passes via facilitated transport. Glucose and galactose both use cotransport with sodium.
What is the path of absorption for proteins?
Amino acids are absorbed via cotransport with sodium.
What is the path of absorption for fats?
1) fatty acids and monoglycerides enter the intestinal cells via diffusion
2) fatty acids and monoglycerides are recombined with other lipids and proteins within the cells. The resulting chylomicrons are extruded via exocytosis.
3) The chylomicrons enter the lacteals of the villi and are transported to the systemic circulation via the lymph in the thoracic duct.
What is the path of absorption for nucleic acids?
- units enter intestinal cells by active transport via membrane carriers
- units are absorbed into capillary blood in the villi and transported to the liver via the hepatic portal vein.
What is the importance of the liver to digestion?
Producing bile for fat emulsification
What is enterohepatic circulation?
a recycling mechanism for bile salts
What is the role of the gallbladder?
stores bile that is not immediately needed for digestion
What is the role of the digestive tract in terms of vitamin, electrolyte, and water absorption?
- small intestine absorbs dietary vitamins
- large intestine absorbs K + B vitamins that are created by helpful microflora
- fat soluble vitamins (A, D, E, K) dissolve in dietary fats and become incorporated into the micelles, which move by diffusion
- most ions are actively absorbed along the entire length of the small intestine, but iron and calcium largely in the duodenum
What is the role of the large intestine in the digestive process?
- absorb most of the remaining water from indigestible food residues
- store the residues temporarily
- eliminate as stool
What are 3 symptoms of asthma?
- shortness of breath
- coughing
- wheezing
What is the function of the loop of Henle?
It creates a concentration gradient between in the interstitial fluid so that water can be reabsorbed as urine passes down the collecting duct
What are the main functions of the kidney?
- Regulating the total volume of water in the body and the total concentration of solutes in that water (osmolality)
- Regulating the concentrations of the various ions in the extracellular fluids. (Even relatively small changes in some ion concentrations such as K+ can be fatal.)
- Ensuring long-term acid-base balance
- Excreting metabolic wastes and foreign substances such as drugs or toxins
- Producing erythropoietin and renin, important molecules for regulating red blood cell production and blood pressure, respectively
- Converting vitamin D to its active form
- Carrying out gluconeogenesis during prolonged fasting
How do substances move out of the PCT cell, such as glucose and amino acids?
Via facilitate diffusion
In the PCT, what things do you need in order to be able to move water?
- concentration gradient
- aquaporins