Lec 14 Osmoregulation

Question 1

What is diffusion?

Answer 1

The movement of ions and molecles through a medium, from high concentration to low concentration

Question 2

What is osmosis?

Answer 2

movement of water across semi permeable membrane. Concentration of solutes is greater on one side of the membrane than the other. Movement of water goes from less concentration to greater concentration of solutes.

Question 3

What does osmotic equilibrium mean?

Answer 3

principal ions found in fluids that are in the body are the same concentration as those in seawater

Question 4

What is an isotonic environment?

Answer 4

rate of diffusion of water into body is the same as the rate to which it diffuses out.

Question 5

How did the primitive kidney function?

Answer 5

function to get rid of body waste materials. It was excretory in function rather than osmoregulatory.

Question 6

What is the law of osmosis

Answer 6

any animal submerge in freshwater with body fluids in greater concentration than surrounding water inevitably take in excess water.

Question 7

how does the early vertebrates that took to freshwater get waterlogged?

Answer 7

1. Absorption through the epithelium covering the gill filaments and mucous membranes of mouth
2. swallowing water along with food

Question 8

What type of mechanism is needed for the Law of diffusion and osmosis in freshwater fishes?

Answer 8

Osmosis: to get rid of excess water
diffusion: mechanism to prevent loss of salts

Vertebrate kidney, eliminates excess water and reclaim salts

Question 9

What is the vertebrate kidney made of?

Answer 9

Thousands of nephrons

Question 10

Each nephron has three components, what are they?

Answer 10

1. Glomerulus
2. Convoluted or nephric tubule
3. Longitudinal collecting duct

Question 11

What is a glomerulus?

Answer 11

Tuft of blood capillaries surrounded by a capsule of tissue called bowman’s capsule.

Question 12

What is the renal corpuscle?

Answer 12

The glomerulus and capsule.

Question 13

What does the glomerulus do?

Answer 13

With help of blood pressure, functions to filter water and other fluid substances.

Question 14

What are the filtered substances called?

Answer 14

Glomerular filtrate.

Question 15

What does the convoluted tubule?

Answer 15

a duct that collects the glomerular filtrate from glomerulus and transports it to the longitudinal collecting duct.

Question 16

Substances are reabsorbed by the bloody by means of a second capillary bed. What is it supplied by and drained by?

Answer 16

Supplied by afferent renal venule and drained by efferent renal venule.

Question 17

What does the longitudinal collecting duct do?

Answer 17

Receives all of the glomerular filtrate from thousand of kidney tubules and dump it into the urinary bladder.

Question 18

What are the two critical functions of each nephron?

Answer 18

1. Glomerular mass, embedded in the bowman’s capsule. Acts as a filter to remove excess water and other substances
2. reabsorptive mass surrounds the convoluted tubule and function to reabsorb water and other valuable substances, i.e salts.

Question 19

What does it mean when an animal exists in hypotonic env?

Answer 19

There’s a higher water concentration in the fish compared to the env.

Question 20

What do animals do when they exist in hypotonic env to balance itself?

Answer 20

1. drinks very little water
2. numberous large well developed glomeruli
3. reabsorbs salts along the conoluted tubules
4. produce large amounts of very dilute urine (5-12% of body weight a day)

Question 21

Describe the glomerulus

Answer 21

a typical kidney of a freshwater fish that has tens of thousands of large glomeruli and well developed bloody supply. A lot of water passes through it and glomerulus provides a filtrate that can be modified by the kidney tubule.

Question 22

Describe what the neck region is lined with

Answer 22

Lined with cilia, the ciliary action plays an important role in aiding movement of materials into the tubule. important in low pressure filtration systems of fishes.

Question 23

What happens at the first proximal segment

Answer 23

reabsorption of many macromolecules, such as glucose and proteins, also excrete organic acids

Question 24

What occurs at second proximal segment?

Answer 24

Largest region of the tubule, where there is a high metabolic activity, es active transport mechanisms that are reabsorption of many salts

Question 25

What occurs at the distal segment?

Answer 25

this protion of the tubule participates in active reabsorption of Na and Cl.
highly ciliated area that assist in propulsion of fluid along tuble.

In fresh water it’s important to mvoe the fluid through the tubule as fast as possible to minimize passive reaborption of water

Question 26

What occurs at the collecting tubule or duct

Answer 26

function primarily to reabsorp monovalent ions, mostly Na and Cl

Question 27

How is nitrogenous waste lost?

Answer 27

Bulk passes out through the gills in form of ammonia

Question 28

Since kidney alone can’t reabsorb enough salts to maintain osmoregularity, how is this compensated?

Answer 28

By gills and oral membranes that evolved the ability to absorb ions by active transport mechanisms in special cells called chloride cells.

Question 29

What happens to marines fishes? Hyper or hypnotonic?

Answer 29

Hypertonic, less water inside than outside. So higher solution concentration inside than outside. So they’re forced to conserve water and get rid of salts.

Question 30

How do you conserve water and get rid of salts?

Answer 30

1. Drink seawater
2. have fewer and small glomeruli
3. excrete salts along the length of its convoluted tubules
4. produce small amnt of very concentrated urine.