Endocrine System: Questions for Bio Test

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Discussion Overview

The discussion revolves around questions related to the endocrine and nervous systems, specifically focusing on the roles of endocrine and exocrine glands, the regulation of sodium levels by ADH, and the mechanisms of depolarization in neurons. The scope includes conceptual understanding and clarification of biological processes relevant to a biology test.

Discussion Character

  • Conceptual clarification
  • Debate/contested
  • Homework-related
  • Technical explanation

Main Points Raised

  • Some participants propose that both endocrine and exocrine glands secrete hormones, while others argue that exocrine glands do not secrete hormones and are therefore not part of the endocrine system.
  • There is uncertainty about whether exocrine glands solely secrete substances through ducts or if they also play a role in hormone secretion.
  • One participant suggests that an increase in water concentration in the blood would dilute sodium concentration, while another questions how increased solvent concentration affects forces within blood vessels.
  • Participants express differing views on the mechanics of depolarization, with some suggesting that sodium/potassium pumps are aligned with axons and activate during the all-or-none firing principle, while others provide a more detailed but uncertain description of the process.

Areas of Agreement / Disagreement

Participants do not reach consensus on the role of exocrine glands in the endocrine system, and there are multiple competing views on the mechanisms of sodium regulation by ADH and the process of depolarization.

Contextual Notes

Some claims rely on specific definitions of glands and their functions, and there are unresolved details regarding the physiological processes discussed, particularly in relation to sodium and water balance and the mechanics of neuronal firing.

student007
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I have a bio test tomorrow on the endocrine and nervous systems, and i have a few questions.
1) Are the endocrine glands and the exocrine glands both part of the endocrine system?
2) For exocrine glands, do the glands just secrete the hormones through ducts or tubes, or do they actually use these hormones (e.g. tear and sweat glands)?
3) How does ADH regulate Na levels if it only controls water permeability? (if there's more water in the blood, would the Na conc. just decrease?)
4) How does depolarization work, that is, is there a Na/K pump after every K and Na "door"? (i.e. the impulse travels like so: K(open)Na(closed)-->K(closed)Na (open) --> Na/K pump...and this repeats)

Test is tomorrow - thanks.
 
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Show us some of your thoughts on all your questions (like you did for question 3) and then we can try and steer you in the right direction. For the yes/no answers, it will help to explain your reasoning. :smile:
(see forum's https://www.physicsforums.com/showthread.php?t=28)

Q3: you said: "if there's more water in the blood, would the Na conc. just decrease?"
Comment: what happens when the solvent (water) concentration increases but the ion (sodium) concentration remains constant? how does this change in liquid volume affect the forces inside the vessel (capillaries, veins, arteries, etc...)?
 
well, for: 1) i would say yes because they both secrete hormones
2) no idea. because our notes only focus on endocrine glands
3) if water conc increases, then sodium conc. decreases because it pretty much becomes diluted.
4) i would think that there is sodium/potassium pump after each pair of channels, so that the concentration of K and Na can return back to normal before depolairzation continues, but I'm not sure.
 
1) No, exocrine glands don't secrete hormones, therefore are not part of the endocrine system. They secrete other substances, like pancreatic juices through ducts, whereas endocrine glands do not have ducts and secrete horomones right into the bloodsystem. Note that the pancreas is an exocrine and an endocrine gland, it secretes both hormones right into the bloodstream and other substances (juices) through ducts.
2) Exocrine glands don't secrete hormones. They secrete other substances through ducts. If you have a test on the nervous system and endocrine system, you should not be asked about exocrine glands ACCEPT, you will likely get this Q:

Which gland is exocrine and endocrine? Answer: Pancreas.
 
student007 said:
3) How does ADH regulate Na levels if it only controls water permeability? (if there's more water in the blood, would the Na conc. just decrease?)

elevated level of salt will osmotically pull water from the surrounding tissues, thereby raising the blood pressure. likewise, raising the volume of water in the blood will cause Na to diffuse into the blood.
 
4): Depolarization: the idea is that the axons are aligned with Na+/K- pumps such that
when the all-or-none firing principle occurs these pumps activate letting mostly Na+ in
(can't remeber but i believe K- out-pumps don't open till around -40 thus leading to the quick rise in the peak) once the 0 threshold or was it +30 threshold is reached. the Na+
in-pumps close(i odn't think the K- pumps close at the peak..but you should search for google for that)

Hyperpolarization: once the Na+ in-pumps close the Na+ out-pumps open and the reverse process hyperpolarization begins. K- out-pumps close. and K-inpumps open as

the refractory period: is caused when hyperpolarization overshoots the resting...that is to much Na+ is let in so there's a time in which some Na+ or Cl- is exchanged..sorry my neurophysiology is long lost.

you should also loook into Cl- pumps I believ they flow opposite to K- and are less concentration(thus minimal)
 

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