Chapter 44: Osmoregulation and excretion

Question 1

Osmoregulation

Answer 1

The regulation of water and fluids in your body

Question 2

Osmosis

Answer 2

Water moving across a membrane, high water concentration to low water concentration

Question 3

Osmolarity

Answer 3

The concentration of solutes in a given area of water

Question 4

Stenohaline

Answer 4

Animal which cannot tolerate a high change in their environments osmolarity

Question 5

Euryhaline

Answer 5

Can tolerate high changes in their environments osmolarity
Ex: Salmon

Question 6

Anhydrobiosis

Answer 6

The ability of an animal to survive in a dormant state when the water they live in dries up

Question 7

Transport epithelia

Answer 7

Tissue which controls how much solute moves across a membrane

Question 8

Peritubular capillaries

Answer 8

Tiny blood vessels in the kidneys which filter waste from blood

Question 9

Vasa recta

Answer 9

Capillaries which surround the loop of Henle

Question 10

Juxtaglomerular apparatus

Answer 10

Part of RAAS, releases renin

Question 11

If two solutions differ in osmolarity, in which direction will water flow?

Answer 11

Lower concentration (hypoosmolality) to higher concentration (hyperosmolarity)

Question 12

What is the difference between an osmoconformer and an osmoregulator?

Answer 12

Osmoconformer: does not actively change, stays the same as its environment
Osmoregulator: will actively change to stay at a set point

Question 13

What is the mechanism utilized by marine birds that allows them to survive on seawater as their source of drinking water?

Answer 13

Salt glands, which filter out salt from seawater

Question 14

What is the relationship between the type of nitrogenous waste an animal produces and its environment?

Answer 14

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

Question 15

What is the main advantage and the main disadvantage of producing uric acid as a waste product instead of urea?

Answer 15

Advantage: saves a lot on water, and is really light
Disadvantage: really expensive to make

Question 16

What are the four basic steps common to excretory systems that produce urine?

Answer 16

Filtration, Reabsorption, Secretion, and Excretion

Question 17

What are the major organs of the human excretory system?

Answer 17

Kidneys, urinary bladder, and urethra

Question 18

What is a nephron and what are its parts?

Answer 18

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

Question 19

What are the two distinct regions of the mammalian kidney called, and which parts of the nephron are found in each?

Answer 19

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

Question 20

What are the functions of the afferent arteriole, efferent arteriole and collecting duct?

Answer 20

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

Question 21

What is the difference between a cortical and juxtamedullary nephron?

Answer 21

Cortical: Short loop of Henle that does not extend much into the medulla
Juxtamedullary: Long loop of Henle which extends far into the medulla

Question 22

What term is used to describe a countercurrent system in which energy is expended to establish a concentration gradient?

Answer 22

Countercurrent multiplier system

Question 23

What is the role of ADH in water conservation by the kidney?

Answer 23

They send a signal to release aquaporins which take in water at the collecting ducts

Question 24

Describe how the renin-angiotensin-aldosterone system (RAAS) works to increase blood volume and pressure

Answer 24

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

Question 25

What is the relationship between RAAS and atrial natriuretic peptide (ANP)?

Answer 25

ANP prevents the release of renin as a reaction to high blood pressure, lowering blood pressure