Which of the Following Is True?

Worksheet 17

1. Which of the following is true? a. Osmoconformers osmoregulate their bodies to be isotonic to their surroundings – Osmoconformers do not osmoregulate b. Protonephridria, like the metanephridria and the kidneys, osmoregulate and remove N waste – don’t do N waste c. Malpighean tubules are involved in the removal of salts, water, nitrogenous waste, and fecal material d. Fish excrete nitrogenous waste through their gills – salt, not N e. None of the above

2. If you find an animal that uses eggs to reproduce, what would its N-waste probably be stored as? a. Urea b. Uric Acid – the most efficient at storing N- need this because you’re in an enclosed environment c. Liquid nitrogen d. Ammonium e. Ammonia

3. Why is urea removed from the distal tubule? a. It must be removed in order to be secreted b. Upon reintroduction to the ascending loop, it causes a greater concentration of NaCl c. It is used to create a osmotic gradient d. To remove water from the nephron e. More than one of the above

4. Which of the following is false? a.i. The spermatogonium does meiosis to produce early sperm cells – spermatogonium does mitosis to yield primary spermatocyte, which does meiosis to make sperm a.ii. Leydig cells in the seminiferous vesicles are responsible for hormone production in the gonads- leydig cells are outside of the seminiferous vesicles. Sertolis are inside and act as life support for sperm a.iii. The corpus cavernosum is the erectile tissue on either side of the penis b. I c. II d. III e. I, II f. I, II, III

5. Discuss the different types of osmoregulatory systems we discussed in the lecture seen across the animal kingdom.

• Protonephridria = Many tubules going throughout body • There are many flame bulb cells with cilia that beat to create a flow of water out of body • Nitrogenous waste is NOT involved in this system • Pretty much only water is expelled by this • Has many many tubes- common theme in excretory systems

• Metanephridia of the earthworms are tubules that collect coelomic fluid and produce dilute urine • Expels N waste as well as excess water/salts

• Insects have malpiaghian tubules • They are extentions of the gut • They can do reabsorption of good stuff before excretion • Expel fecal material with nitrogenous waste

6. How is N-waste expelled across the phyla of the animal kingdom? What are the advantages of each? Disadvantages?

• Nitrogen comes from proteins or nucleic acids • Most bony fish get rid of N through use of ammonia • Most mammals, sharks, and some fish use urea • Reptiles and birds and some insects use uric acid • Ammonia, urea, uric acid is the descending order of water saving versus energy saving • Ammonia and urea are less water efficient because they are dangerous at lower concentrations, thus requiring more water to be excreted • Uric acid is used in things that have eggs- uric acid condenses and is very efficient at storing N, baby would die if it used urea or ammonia • Test Q: if you find an animal that uses eggs to reproduce, what would its N probably be expelled as? • Fetuses and adults can use different excretion types- uric acid as fetus in egg- urea as adult

7. Describe the kidney.

• Red arrow means active transport • Blue arrow means passive transport • What is being reabsorbed? • What is being secreted? • How does stuff get into nephron • Goes to glomerulus, • in bowmans capsule there are filters known as podocytes • Blood pressure actually moves things out of blood (glomerulus) and into bowmans capsule- anything small enough goes out • Once it goes out of bloodstream, goes into nephron and moves down- at this point it would be very similar to plasma- has lots of good stuff (75% of the stuff in your veins gets dumped out, but vast majority is quickly reabsorbed) • Your body wants to get rid of the most amount of stuff with the least amount of water- hypertonic urine. But if you’re overhydrated, it’ll make your pee more dilute • Lots of stuff will be absorbed back through passive osmotic movement, but some is done through active transport • Some bad things will be actively secreted into nephron Nutrients are absorbed back through active transport- done actively because passive only gets back 50% • Glucose in urine is a common indicator of diabetes • Active movement of salt in order to bring back water passively- water follows concentration gradient • Potassium, bicarbonate are taken passively • Ammonia moves into nephron from interstitial fluid at proximal tubule, as well as H+ • In the loop of henle there is a countercurrent exchange system • Descending is only water permeable, while the ascending loop is permeable to ascending loop • Lower part of ascending loop is passive, but the top is active • This causes water to follow concentration grade out of nephron • At the distal tubule, it’s a final check that isn’t necessarily essential • NaCl is active, water is active, Bicarb is active going out of nephron • K+ and H+ can be actively moved into the nephron • In the collecting duct, you can take back water or urea actively, but don’t have to • Urea is taken back out of the nephron in order to cause water to follow its concentration gradient out of the nephron • It will move back into the nephron in the ascending loop of henle- eventually released • This causes much more concentrated urine

8. What are some ways in which the functions of the kidney can be controlled? • Blood circulates in hypothalamus- hits osmoregulators • Osmoregulators detect blood is too thick- causes thirst and releases ADH • ADH goes to distal tubule of collecting duct and causes water to be absorbed more efficiently. • Kidney is also regulated by juxstaglomerular aparatus (JGH) • Afferent arteriole leading to the glomerulus • Stimulated by low blood pressure or low volume to produce renin • Angiotensinogen is actived by renin, which is released by JGH • Angiotensinogen gets converted to angiotensin i, • Angiotensin I gets converted to angiotensin II by ACE enzyme • A II causes arteries to constrict, increasing BP • Causes adrenal cortex (one of 2 places to produce steroid hormones) to produce aldosterone (it’s a steroid) • Aldosterone causes more sodium ions, and therefore water to be absorbed- increase Blood volume •

Atrial naturetic protein opposes both ADH and JGA • Is released by the atria in response to increased blood volume and pressure • Decreases sodium reabsorption- lowers blood pressure and blood volume

9. Where and how is sperm produced? • Sperm production happens in the seminepharous tubules in the testes • When males are born, these are chords. As you go through puberty- turns to tubes • Two types of cells in the seminiferous tubule- developing sperm and sertoli cells • Sertoli cells keep bloodstream from coming into contact with sperm (otherwise immunity would kill it). Also nourish and protect sperm cells. Have tight junctions • Between the seminiferous tubules there are leydig cells- this is where testosterone comes from •

• Sperm is produced from primordial germ cells in the embryo • Becomes spermatogonial stem cell • Does mitosis to produce more spermatogonial stem cells and spermatogoniums • Spermatogonium does mitosis to make primary spermatocyte • Primary spermatocyte does meiosis I to make secondary spermatocyte • does meiosis II to make early spermatids • Spermatids develop to sperm • Primary spermatocyte is the final diploid state • All coiled up on top of the seminiferous tubules in the testes is the epididymis- place to store sperm and matures sperm further- this is where sperm develops ability to use flagella •

10. What are the accessory structures? What do they do? • Vas deferens- tube from the testes to the penis where sperm goes through during ejaculation • Seminal vesicles add secretions to sperm to make semen- adds 60% of fluid- mucus, fructose (energy for sperm), prostoglandins (cause muscle contractions), coagulation enzyme (makes a plug in the vagina- doesn’t allow other males to reproduce with her, slowly releases sperm) • Prostate gland releases buffers that make female reproductive tract more hospitable • Prostate gland usually gets larger as you get older • Bulbourethral gland- mucus to neutralize urine pH in vas deferens

11. What are some of the structures involved in the penis?

• Erection is caused by blood flowing into erectile tissue • Blood flows through loosening veins into the penis • Corpus cavernosum – on either side • Corpus spongium- around the urethra