Chapter 44: Osmoregulation and excretion Flashcards
Osmoregulation
The regulation of water and fluids in your body
Osmosis
Water moving across a membrane, high water concentration to low water concentration
Osmolarity
The concentration of solutes in a given area of water
Stenohaline
Animal which cannot tolerate a high change in their environments osmolarity
Euryhaline
Can tolerate high changes in their environments osmolarity
Ex: Salmon
Anhydrobiosis
The ability of an animal to survive in a dormant state when the water they live in dries up
Transport epithelia
Tissue which controls how much solute moves across a membrane
Peritubular capillaries
Tiny blood vessels in the kidneys which filter waste from blood
Vasa recta
Capillaries which surround the loop of Henle
Juxtaglomerular apparatus
Part of RAAS, releases renin
If two solutions differ in osmolarity, in which direction will water flow?
Lower concentration (hypoosmolality) to higher concentration (hyperosmolarity)
What is the difference between an osmoconformer and an osmoregulator?
Osmoconformer: does not actively change, stays the same as its environment
Osmoregulator: will actively change to stay at a set point
What is the mechanism utilized by marine birds that allows them to survive on seawater as their source of drinking water?
Salt glands, which filter out salt from seawater
What is the relationship between the type of nitrogenous waste an animal produces and its environment?
Animals who have easily accessible water get rid of it as ammonia, which cannot build up for too long and must be constantly removed
Animals with regular access to water or that can’t lose as much water must get rid of it as urea, which is more expensive to make but not as toxic and saves on water
Animals which little access to water get rid of waste as uric acid, barely toxic, takes a lot of energy to make, but is really water efficient
What is the main advantage and the main disadvantage of producing uric acid as a waste product instead of urea?
Advantage: saves a lot on water, and is really light
Disadvantage: really expensive to make
What are the four basic steps common to excretory systems that produce urine?
Filtration, Reabsorption, Secretion, and Excretion
What are the major organs of the human excretory system?
Kidneys, urinary bladder, and urethra
What is a nephron and what are its parts?
The functional part of the kidney.
Glomerulus: Ball of capillaries, brings stuff to nephron
Bowman’s capsule: Takes filtrate from the glomerulus
Proximal tubule: Reabsorbs solutes the body may want
Loop of Henle: Descending catches water, ascending catches salt
Distal tubule: Regulates the potassium and sodium
What are the two distinct regions of the mammalian kidney called, and which parts of the nephron are found in each?
Renal cortex: Outer layer, contains cortical nephrons, everything but the loop of Henle
Renal medulla: Inner area, contains Juxtamedullary nephrons, has the loop of Henle
What are the functions of the afferent arteriole, efferent arteriole and collecting duct?
Afferent arteriole: Brings blood to the nephron
Efferent arteriole: Brings blood away from the nephron
Collecting duct: Collects filtrate from the renal medulla and brings it to renal pelvis, some water is lost here making the filtrate even more concentrated
What is the difference between a cortical and juxtamedullary nephron?
Cortical: Short loop of Henle that does not extend much into the medulla
Juxtamedullary: Long loop of Henle which extends far into the medulla
What term is used to describe a countercurrent system in which energy is expended to establish a concentration gradient?
Countercurrent multiplier system
What is the role of ADH in water conservation by the kidney?
They send a signal to release aquaporins which take in water at the collecting ducts
Describe how the renin-angiotensin-aldosterone system (RAAS) works to increase blood volume and pressure
A drop in blood pressure near the glomerulus causes a release of renin, renin then causes a series of reactions that lead to the creation of angiotensin which creates angiotensin II, this raises blood pressure to rise by contracting arterioles that lead to the kidneys. It also leads to the creation of aldosterone which increases reabsorption of sodium and water at the distal tubes
What is the relationship between RAAS and atrial natriuretic peptide (ANP)?
ANP prevents the release of renin as a reaction to high blood pressure, lowering blood pressure
