Biology Chapter 10: Digestive and Excretory Systems Flashcards
What is the glomerulus? And where does it live?
The glomerulus filters blood, allowing water, ions, and small molecules (like glucose and amino acids) to pass through while retaining larger molecules (like proteins) and blood cells. This process forms the glomerular filtrate, which becomes the basis for urine after further processing in the nephron.
Lives in the renal corpuscle which sits in the renal cortex
What does the bowman’s capsule do and where does it live?
Collects the filtrate from the glomerulus. Lives in the renal corpuscle of the nephron which sits in the renal cortex
What is the purpose of the glomerulus and bowman’s capsule?
filter the blood, separating smaller molecules like water, ions, glucose, amino acids, urea, and other small solutes from larger components like blood cells and plasma proteins. This process forms the glomerular filtrate, which enters the nephron for further processing.
What gets reasborbed in the proximal tubule and where does it live?
Water and nutrients such as glucose, amino acids, potassium, calcium
Does the medulla have a high or low salt concentration?
Medulla is very salty
What is reabsorbed in the descending loop of henle?
Water. Medulla is salty so water diffuses into the medulla for reabsorbed by osmosis
What is reabsorbed in the ascending loop of henle and why?
Ascending loop of henle is impermeable to water. Na+ and Cl- are actively transported into medulla
What is reabsorbed at the distal tubule?
H2O and salt
Distal convoluted tubule is located where?
In the renal tubule, which sits in the renal cortex
ADH promotes water reabsorption on what part of the kidney?
Mostly on the collecting duct but a bit on the DCT. Increased ADH when we’re dehydrated = more water retained
Aldosterone acts on where and does what?
Acts on the DCT and the collecting duct to promote reabsorption of sodium
Parathyroid hormone acts where and does what
Acts on the DCT to promote Ca reabsorption
ANP has what effect?
ANP has opposite affect to aldosterone. It promotes excretion of sodium in the urine and draws water with it - increasing amount of water expelled and decreasing blood pressure
Definition of osmolarity and why ADH reduces osmolarity of the blood
is the measure of the concentration of solute particles in a solution, expressed as the number of osmoles of solute per liter of solution (osmol/L).
ADH reduces blood osmolarity because it increases water retention without increasing solute levels, effectively diluting the blood.
Where are hydrogen ions and potassium ions secreted into the excretory system?
Secreted into the distal convoluted tubule
Urea
nitrogen-containing compound that is the primary end product of protein metabolism in humans and many other animals. It is produced in the liver through the urea cycle, which converts toxic ammonia (a byproduct of amino acid breakdown) into urea, a less toxic and more water-soluble molecule.
What is the renin-aldosterone system (RAAS)?
hormone cascade that regulates blood pressure and fluid balance. When blood pressure or sodium levels drop, renin from the kidneys activates angiotensin II, which constricts blood vessels and stimulates the release of aldosterone from the adrenal glands, promoting sodium and water retention to restore blood pressure and volume.
Point of confusion: reabsorption vs secretion
Reabsorption: goes from tubule BACK into the body
Secretion: INTO tubule for excretion
Why would water remain in the lumen of the large intestine as a result of excess cellulose consumption?
Cellulose can’t be digested or absorbed and therefore stays in the digestive tract, increasing osmolarity. Therefore less water will be absorbed back into the body.
What does liver cirrhosis involve?
involves fluid retention and improper regulation of body fluids
How would a vasopressin receptor antagonist address a patient’s hypoatremia due to liver cirrhosis
Liver cirrhosis = hypoatremia caused by excessive water rentention
Need to decrease water retention
Therefore would need to down regulate vasopressin
Difference between uvula and epiglottis
epiglottis closes off the trachea to protect the airway during sallowing
uvula and soft palate work together to close off the nasopharynx to prevent the entry of substances from the oral cavity.
What produces bile?
The liver. The liver also secretes bile
What stores bile?
The gall bladder. It also concentrates bile.
Once nutrients are absorbed, they are transported to the
liver via the hepatic portal vein. This allows for nutrient-rich blood to be balanced and detoxified before it is delivered to the rest of the body.
why does salt get actively transported into the medulla in the acsending loop of henle
Salt (NaCl) is actively transported into the medulla in the ascending loop of Henle to establish and maintain the medullary osmotic gradient, which is crucial for water reabsorption and urine concentration. Here’s why this happens:
- Creating the Medullary Osmotic Gradient
The kidney needs to create a hyperosmotic environment in the medulla so that water can be reabsorbed from the collecting duct later.
The ascending limb of the loop of Henle actively transports Na+ and Cl− ions into the medulla, increasing the osmolarity of the interstitial fluid.
This high osmolarity allows water to be passively drawn out of the descending limb and the collecting duct, concentrating the urine. - The Ascending Limb is Impermeable to Water
Unlike the descending limb, the ascending limb is impermeable to water, meaning water cannot follow the salt.
This ensures that the medullary interstitial fluid becomes hypertonic, drawing water out from other parts of the nephron. - Countercurrent Multiplication
This active transport of salt is part of the countercurrent multiplier system, which:
Amplifies the osmotic gradient along the length of the nephron.
Enhances water reabsorption in the collecting duct, helping to conserve water in the body.
